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WCDMA Mobility Troubleshooting Studies and Enhancements

1. ceeeeessteeeceeeeeeeeeeenneees 20 3 2 Hatidover Controleren ar ar an ar E EEE E EREA 21 3 3 Handover Measure mic mts ccs 425 cesacadsten voice neree teach ech beads aie a ae 29 4 Radio Network Controller RNC cccccccccccccccsssssseecceceeeeesseeseesecceeseeaaaanseeeeeess 40 4 1 UTRAN network elements Standard concept cccccceceeeeeeeeeeteeeeeeeeeeeeees 40 4 2 Nokia Siemens Networks RNC Solutions eeeescsccccccceeeeeeennnneeeeeeeeeeeeee 41 4 3 RNC SW Architecttre icici sctisecs isidis deiei ara Gua wud aian 45 4 4 Radio Resource Management of WCDMA RAN Service Block 48 4 5 Handover Control Process Family sssesesseesssssssesererssssssserereessssssserereeesss 54 gt Lroubleshootiie Experenees ecas eroris psa ar Ea E ES e EEEE EEE T E 57 5 1 Troubleshooting Approach for Mobile Networks eeeseseeeeeeeeeeerereesereresseee 57 X2 EMIn ndn an n a A aR 59 5 3 Challenges to be studied related with Handover Control Algorithm 60 Ei TAOTE O a E E E E E 80 References aien tac steelcnt ten tend rea e a e EA e E nE EEDEN ERE 83 Ape S a E A e a aN 85 6 1 Datatypes neheni 85 vii List of Acronyms 2G 3GPP 8PSK A GPS AC ACK ADJD ADJG ADJS ALCAP AMPS AS ASU AT amp T ATDMA BCC BCCH BER BLER BoD BSC BSIC BSS BTS C NETZ CDMA CFCP CGI CI CIO CM 2nd Generation 3rd Generation Partner Project Eight Phase Shift Keying Network Assisted
2. Higher cell capacity and higher spectral efficiency are required to provide higher data rates and new services with the current base station sites Basic HSPA includes a one antenna Rake receiver in the terminals and two branch antenna diversity in the base stations Enhanced HSPA includes two antenna equalizer mobiles and interference cancellation in the base station The simulation results show that HSPA can provide substantial capacity benefit Basic HSDPA offers up to three times WCDMA downlink capacity and enhanced HSDPA up to six times WCDMA The spectral efficiency of enhanced HSDPA is close to 1 bit s Hz cell The uplink capacity improvement with HSUPA is estimated between 30 and 70 HSPA capacity is naturally suited for supporting not only symmetric services but also asymmetric services with higher data rates and volumes in downlink 8 pp 7 20 3 Mobility in UMTS 3 1 Introduction to Radio Resource Management The task of Radio Resource Management RRM is to optimize the use of the available resources such as transmitter power and spreading codes in order to provide users with the largest possible capacity for a specified coverage and quality of service QoS This is achieved through the concerted effort of a number of closely inter related radio resource management algorithms The algorithms can be divided into cell based and connection based algorithms on the basis of their different purposes Cell Based Algorithms Adm
3. HSPA Standardization and Deployment Schedule 9 pp 7 3GPpP R9 3GPP R10 appas 30PPRT 3GPP R8 2128 i 42 Mbps 4 carrier P 14 Mbps Mbps DC HSDPA HSDPA m a i p B4AQAM or DC HSDPA MIMO Downlink MIMO Mbps i 23 T 11 Mbps I n 5 8 Mbps DC HSUPA 0 4 Mbps 16QAM Uplink Figure 13 HSPA Evolution 8 pp 4 HSPA is deployed on top of the WCDMA network either on the same carrier or for a high capacity and high bit rate solution using another carrier demonstration can be seen in Figure 14 In both cases HSPA and WCDMA can share all the network elements in the core network and in the radio network including base stations Radio 18 Network Controller RNC Serving GPRS Support Node SGSN and Gateway GPRS Support Node GGSN WCDMA and HSPA are also sharing the base station sites antennas and antenna lines Base RNC 3G SGSN GGSN station Figure 14 HSPA deployment with f2 new carrier deployed with HSPA and f1 carrier shared between WCDMA and HSPA 8 pp 5 The performance of the radio system defines how smoothly applications can be used over the radio network The key parameters defining application performance include data rate and network latency There are applications that are happy with low bit rates of a few tens of kbps but require very low delay like voice over IP VoIP and real time action games On the other hand the download time of a large file is only defined by the maximum data
4. The BSIC can be used additionally to verify identification if two or more neighbouring GSM cells have the same BCCH frequency The RNC always applies the BSIC verification for the target cell before the execution of IS HO so that the UE can synchronise with the GSM cell before HO execution The UE reports the BSIC information only if it is requested by the RNC 33 The UE generates at least the following event triggered and periodic measurement reports 10 pp 217 3 3 3 1 event triggered intra frequency measurement report periodic intra frequency measurement report inter frequency measurement report inter system measurement report measurement reports on common channels traffic volume measurement report UE internal measurement report quality deterioration report Reporting of Intra frequency Measurements Intra frequency measurement reporting can be either event triggered or periodic During connected mode the UE constantly monitors the P CPICH E I of the cells defined by the intra frequency neighbour cell list and evaluates the reporting criteria If one of the reporting events is fulfilled the UE sends an event triggered measurement report Before the P CPICH E I of a cell is used by the HO algorithm in the UE an arithmetic mean of a certain number of the latest measured values is taken The number of the values taken into account is a UE performance specification parameter The average is taken over the li
5. i e user information bits are spread over a wide bandwidth by multiplying the user data with quasi random bits called chips derived from CDMA spreading codes In order to support very high bit rates up to 2 Mbps the use of a variable spreading factor and multi code connections is supported Codes with different spreading giving 8 384 kbps Variable bit rate user High bit rate user Figure 9 Allocation of bandwidth in WCDMA in the time frequency code space 4 pp 48 15 WCDMA is designed to be deployed in conjunction with GSM Therefore handovers between GSM and WCDMA are supported in order to be able to leverage the GSM coverage for the introduction of WCDMA WCDMA supports two basic modes of operation Frequency Division Duplex FDD and Time Division Duplex TDD In the FDD mode separate 5 MHz carrier frequencies are used for the uplink and downlink respectively whereas in TDD only one 5 MHz is timeshared between the uplink and downlink Uplink is the connection from the mobile to the base station and downlink is that from the base station to the mobile The TDD mode is based heavily on FDD mode concepts and was added in order to leverage the basic WCDMA system also for the unpaired spectrum allocations of the ITU for the IMT 2000 systems 4 pp 48 The WCDMA air interface has been crafted in such a way that advanced COMA receiver concepts such as multiuser detection and smart adaptive antennas ca
6. pp 222 e Average downlink transmission power of the DPCH e Average measured uplink SIR of the DPCH e Uplink SIR target currently used on the DPCH 40 4 Radio Network Controller RNC 4 1 UTRAN network elements Standard concept Figure 23 UTRAN Network Elements The key functions of the Radio Network Controller RNC are management of terrestrial channels management of radio channel configurations in the Radio Access Network RAN radio resource management telecom functionality transmission amp transport features and maintenance amp operation They are briefly explained in the following sub chapters and more in detail throughout this document Defined RNC roles 13 pp 29 1 Serving RNC Role an RNC can take with respect to a Radio Resource Control RRC connection between an UE and RAN There is one Serving RNC for each UE that has a connection to RAN The Serving RNC is in charge of the radio connection between a UE and the RAN The Serving RNC terminates the Ju interface for this UE 2 Drift RNC A role an RNC can take with respect to a specific connection between an UE and RAN An RNC that supports the Serving RNC with radio resources when the connection between the RAN and the UE need to use cell s controlled by this RNC is referred to as Drift RNC 41 3 Controlling RNC A role an RNC can take with respect to a specific set of BTS s There is only one Controlling RNC for any BTS The Controlling RNC ha
7. 16 41 21 119 16 41 21 20 16 41 21 20 16 41 21 23 t i radioBearerReconfiguration 569 Direction 1 Li h 200 pi RRC measurementRepon gt engt ts DL DCCH Mes integrityc fo message Aw ionCode 10111000100011110011 eNumber 1 iguration later than xtensions r4 r5 uration r5 RNTI 1011110011110000 B StateIndicator cell DCH lcificationMode complete leAddReconfTransChinfobist m di TransportChannelType hsdsch NULL tfs 3ignallingMode hsdsch addOrReconfMAC dFlow mac hs AddReconfQueue List 16 41 21 0 16 41 2200 ime 16 41 21 00 1641 2200 Time _ pme 16 41 21 00 perte p reretdereneres mac haQueueld 0 mac aF Order Message Message Name Time Time ditt 52 Jeare Reconfiguratiq repr io gt 7 ni 570 1a3pl ha3pi 16 41 21 33 00 00 08 69 571 a3prt ia3pil 16 41 21 33 00 00 08 69 572 l SRB2 tx bulter is empty nopit lt ttutor 16 41 21 339 00 00 08 69 57 FIL 3 has PTX 69 hadprb ove nbapb 0036 16 41 21 40 00 00 08 7 574 OEC m uli ind treprby OFC d3p003 oc 16 41 21 41 00 00 08 77 575 iLedu_s SRB2 MeasurementReport 44 b nopiby lt Mutor 16 41 21 64 00 00 09 00 576 CPICH EcNo 7d8 138 1348 nopib gt 16 41 21 64 00 00 09 00 Figure 30 EMIL Screenshot EMIL is an internal troubleshooting tool for Nokia Siemens Networks which can be used for investigating different kinds of message monitoring
8. HSPA cannot be used in that cell meaning no accessibility for high uplink UL bit rates from end user point of view 78 HS DSCH operational state is used by BTS to report to HSDPA operational state of the cell In order to use HSDPA in a cell the BTS must have reported HSDPA Operational state to be enabled in that cell Otherwise HSDPA cannot be used in that cell meaning no accessibility for high downlink DL bit rates HSDPAOperationalState and HSUPAOperationalState indications are the most error prone and also the most difficult one to catch from live network Handover Control Algorithm gets this information from Radio Network Initiator on WBTS cell level basis and there has been some problems that Radio Network Initiator has not always sent this information correctly to Handover Control Algorithm or sometimes it has not sent it at all That will cause huge problems for HS D PA accessibility From end user point of view problem can be seen with lower bit rates than expected because HSDPA or HSUPA cannot be allocated for the user Existing Solution for the problem Currently the R amp D just need to try to get Operation and Maintenance Unit logs from customer and try to search from there by using EMIL any Radio Network Initiator notifications that have been sent to Handover Control Algorithm Live network expectations from the desired tool The tool has to create alarms or warnings for parameter inconsistency and clearly show
9. HSUPA introduced LTE Advanced introduced Multi cell HSDPA 4 carriers introduced Table 2 3GPP Release History in a nutshell 5 2 2 UMTS Radio Access Network Architecture Figure 5 UMTS high level system architecture 4 pp 76 11 In the standardization phase network elements were grouped based on their similar functionality and defined at the logical level The UMTS system consists of a number of logical network elements that each has a defined functionality The User Equipment UE that interfaces with the user and the radio interface is defined the Radio Access Network UTRAN handles all radio related functionality and the Core Network is responsible for switching and routing calls and data connections to external networks s d Figure 6 UTRAN architecture 4 pp 78 UTRAN consists of one or more Radio Network Sub systems RNS An RNS is a sub network within UTRAN and consists of one Radio Network Controller RNC and one or more Node B s RNCs may be connected to each other via an Jur interface RNCs and Node B s are connected with an Jub interface The main characteristic of UTRAN can be summarised in the following points 4 pp79 e Support of UTRA and all the related functionality In particular the major impact on the design of UTRAN has been the requirement to support soft handover one terminal connected to the network via two or more active cells and the WCDMA specific Radio Resource
10. Rx Tx Receiver Transmitter time difference measurement It is used to adjust the downlink DPCH air interface timing when the difference in time between the UE uplink DPCCH DPDCH frame transmission and the first significant path of the downlink DPCH frame from a measured active set cell UE Rx Tx time difference becomes too large 10 pp 221 The following events are specified in 3GPP specifications 12 e Event 6A UE transmit power becomes larger than an absolute threshold e Event 6B UE transmit power becomes less than an absolute threshold e Event 6C UE transmit power reaches its minimum value e Event 6D UE transmit power reaches its maximum value e Event 6E UE RSSI Received Signal Strength Indicator reaches the UE receiver dynamic range e Event 6F UE Rx Tx time difference for a radio link included in the active set becomes larger than an absolute threshold e Event 6G UE Rx Tx time difference for a radio link included in the active set becomes less than an absolute threshold 39 3 3 3 8 Node B Measurements The Node B measurement report can be used to trigger off inter frequency or intersystem GSM measurements and to balance the PC uplink and downlink of the diversity branches during SHO The Node B sends the measurement report to the RNC on a radio link by radio link basis at regular e g 500 1000 ms intervals The measurement report from the Node B includes the following radio link measurement results 10
11. The main enhancement with 2G was digital communication The use of digital transmission brought a number of benefits 2 pp 52 e Increased capacity over analogue e Reduced capital infrastructure costs e Reduced the capital per subscriber cost e Reduced cellular fraud e Improved features such as encryption The benefits listed above mainly helped operators to serve more efficiently higher capacity with less cost to their subscribers The most successful 2G technologies were Interim Standard 136 IS 136 TDMA IS 95 CDMA and the Global System for Mobile communications GSM IS 136 digital AMPS was developed over analogue AMPS system In the first phase time division multiplexing TDM was added only for the voice channels Then in the second phase control channels were also digitalized 3 pp 3 GSM was developed with the standardization movements of European Countries Even though the standardization was done by European initiatives it was aimed to be a global standard As a continuation of NMT900 at first it was standardized to work in 900 MHz but later GSM1800 launched in U K and GSM1900 launched in U S 2 pp 6 CDMA or IS 95 was developed by Qualcomm and standardized in U S Besides from other multiple access methods CDMA uses different codes in the same frequency to share the transmission medium In the next chapters there are detailed explanations about CDMA and wide band CDMA It was used in the United Stat
12. and packet scheduling of base stations e User Equipment Radio Resources Program Block manages UE specific radio resources RNW management can be divided into three functionalities from Radio Resource Management of WCDMA RAN Service Block point of view 13 pp 48 a RNW parameter management contains the management and access routines for the radio network configuration database Radio Resource Management of WCDMA RAN Service Block both reads and receives via message interface radio network parameters from the RNW database in OMU unit However base transceiver station BTS and cell related radio network parameters are delivered inside ICSU CSCP via message interface to Base station Resource Manager Program Block first when BTS cell is setup and thereafter whenever those parameters change 50 b BTS and cell configuration management in ICSU CSCP is responsible for BTS and cell setup and cell state handling inside ICSU CSCP Base station Resource Manager Program Block receives information about cell states through this interface Base station Resource Manager Program Block provides common channel DL spreading codes for CCH setup purposes c BTS and cell recovery management in OMU is responsible BTS and cell recovery procedures This interface is also used for triggering cell recovery procedures PM Service collects statistical counter data from applications PM Service interface is used to deliver statistical coun
13. generation systems IPA2800 was designed to be much simpler than DX200 from the architectural point of view 14 pp 15 42 4 2 2 cRNC cRNC is the classic RNC solution of Nokia Networks and Nokia Siemens networks that has been developed since 90 s The general functional architecture of the RNC is shown in Figure 24 The RNC consists of four parts network interface functions switching and multiplexing functions user plane functions and control functions Figure 24 Functional architecture of the cRNC 13 pp 31 DMCU Data and Macro diversity Combining Unit EHU External Hardware Alarm Unit HDD Hard Disk Drive for OMS ICSU Interface Control and Signalling Unit MXU Multiplexer Unit NPGE Network Processor Interface Units Gigabit Ethernet NPS1 Network Processor Interface Unit STM 1 OMS OMU RSMU SFU SWU TBU WDU 43 Operation and Maintenance Server Operation and Maintenance Unit Resource and Switch Management Unit Switching Fabric Unit Switching Unit Ethernet Timing and Hardware Management Bus Unit Winchester Drive Unit for OMU In the scope of this thesis only Handover Mobility related functional units of CRNC will be analyzed and explained The Operation and Management Unit OMU performs the basic system maintenance functions such as hardware configuration alarm system and centralized recovery functions It also contains cellular related functions such as performance management radio netwo
14. master process to notify that one new set of intra frequency handover path parameters has been created into the RNW RNC database rak_create_ha3_wane_s RNW Manager hand process sends this message to HC master process to notify that one new set of WCDMA authorized network parameters has been created into the RNC RNW database rak_create_ha3_wcel_s RNW Manager hand process sends this message to HC master process to notify that one new WCDMA cell has been created into the RNW RNC database RNW hand process gt Handover Control Algorithm master process WBTS_PARAM Handover Control Algorithm Program Block related WCDMA base transceiver station parameters of the WCDMA cell which is created In ha3_wbts_param_t data type wbts_id defines the identification of the WBTS WCEL_PARAM WCDMA cell parameters which concern only the Handover Control Algorithm processes In ha3_wcel_param_t data type wcel_id identifies a WCEL unambiguously within a RNC rak_create_ha3_wsg_s RNW Manager hand process sends this message to HC master process to notify that one new WCDMA subscriber group has been created to RNC RNW database rak_modify_ha3_rnc_param_s RNW Manager hand process sends this message to HC master process to notify that RNC parameters has been modified 88 rak_modify_ha3_vbts_param_s RNW Manager hand process sends this message to HC master process to notify that VBTS parameters have been modified rak_
15. modulation method Because it had the coexistence with Gaussian minimum shift keying GMSK EDGE upgraded network and also supported old handsets Some operators also used EDGE with their existing GPRS infrastructure and reached to great data rates such as 384 kbps 3 pp 6 In U S there were technologies that can be named as 2 5G One of them was IS 95B which used multiple code channels per user to increase the user data rate The other one was CDMA2000 which was evolved from CDMA IS 95 In Japan NTT DoCoMo introduced its own concept i mode over Personal Digital Cellular PDC Including the internet services i mode concept showed great success and became a business model for new concepts and technologies 3 pp 8 2 1 4 3 Generation In 1988 the RACE I Research of Advanced Communication Technologies in Europe programme started researching for the basics of third generation communications networks Between 1992 and 1995 research continued on CDMA based Code Division Testbed CODIT and TDMA based Advanced TDMA Mobile Access ATDMA in the RACE II project In 1995 Future Radio Wideband Multiple Access System FRAMES project was set up by Advanced Communication Technologies and Services ACTS research group 4 pp 61 ETSI ETSI Decision Concept WCDMA for groups FDD operation RACE I ACTS FRAMES basic FMA1 WTDMA studies FMA2 WCDMA 1988 1992 1995 1997 1998 Figure 2 European research programmes to
16. networks Those changes in the software also created new fields to be debugged and investigated Eventually troubleshooting has become more important and complex for the new systems This work examines the troubleshooting experiences for Handover related issues under Radio Resource Management software block in Radio Network Controller 1 1 Problem Statement and The Objectives There are different types of challenges in WCDMA Mobility part of the RNC software From developers and testers point of view it would be easier for them to investigate those issues by using a specially designed troubleshooting tool or with improvements to the existing tools Most of the existing troubleshooting approaches are based on practical analysis which takes time and usually it is hard to figure out the problem This thesis will analyze the existing challenges and propose better solutions to be implemented by modifying the existing solution or providing a new troubleshooting tool 1 2 Structure of the Thesis This thesis consists of 8 chapters Chapter 1 includes the introduction of the thesis Chapter 2 includes the basic information about WCDMA and HSPA Chapter 3 includes detailed information about mobility concept in terms of UMTS specifications Chapter 4 explains the Radio Network Controller concept and different solution approaches and detailed information about the Handover Control Algorithm Program Block in Radio Network Controller Software C
17. outputs and other log files It supports different software versions different data types and products EMIL provides profiles for different products and Software Program Blocks depending on the needs for effective fault analysis A profile consists of several files which describe how the information in a log file is processed and visualized to the end user The main benefit of the profiles is that they can be modified by users for better visualization of the log files EMIL provides an opportunity to create very powerful automated scripts inside the profiles With the help of those scripts thousands of lines messages can easily be filtered to tens or hundreds of lines which can further be highlighted to identify and visualise the problematic issues better With this flexibility EMIL platform is open for new scripting implementations and it can easily be customized for different needs around the R amp D organization 60 5 3 Challenges to be studied related with Handover Control Algorithm As it is mentioned in the prior chapters RNC software is a very complex product which came to its final phase through proved success in different technologies To keep the same success level continuous in different versions of the software R amp D activities are vital In R amp D mostly Integration amp Verification engineers have the responsibility to keep the software parts compatible with each other and working all the time R amp D suppor
18. possibilities enhancement proposals and testing scenarios for new functionalities 61 5 3 1 Radio Network Database parameter consistency checking RNW RNW Database Database Manager Library Handover Control Hand Process Handover Control LON Master Process Manager Figure 31 Handover Control Algorithm Program Block interactions Problem statement Parameter values in Handover Control HC master memory should be the same as in radio network RNW database Communication between the RNW database and HC master has two interfaces library interface and messaging interface When the unit starts up and Handover Control family is started each HC master uses RNC RNW Database Library procedures to read the needed RNW parameters from the database If parameters are created deleted modified in the database after the unit start up i e during normal operation Radio Network Manager sends notification message to each HC master process about the new removed changed parameters This messaging interface is hidden from the clients with a library If everything works as it should there should not be any inconsistencies But in practice in distributed systems where database users are in different network units than the actual database it is always possible that due to some reason data in different network units is not the same Investigation of this kind of problems is very challenging More specifically there might be differen
19. the UE changes to periodic reporting In this case it sends a measurement report every reporting interval until the active set update has taken place the measurement criteria are no longer fulfilled or the maximum number of measurement reports has been sent 10 pp 220 37 3 3 3 4 Mechanism for Forbidding a Neighbouring Cell to Affect the Reporting Range In case of Events 1A and 1B when the weighting coefficient W is non zero all cells in the active set are used to evaluate whether or not the measurement criteria are fulfilled In a RAN however it could be beneficial to exclude a specific neighbouring cell i e its P CPICH from this active set weighting for example when the P CPICH of that cell is very unstable within the reporting range For this case a neighbouring cell parameter can be specified for each cell indicating whether or not this cell is allowed to affect the reporting range calculation when it is in the active set 10 pp 220 3 3 3 5 Cell individual Offsets To have an efficient means of reporting a monitored cell individually a P CPICH offset can be assigned to each neighbouring cell The offset can be either positive or negative The UE then adds this offset to the measurement quantity E I path loss or RSCP before it evaluates whether a reporting event has occurred 10 pp 220 3 3 3 6 Reporting of Inter frequency and Inter system Measurements Inter frequency and inter system measurement r
20. the studies for this issue R amp D engineers implemented the Database Consistency add on to the Handover Control Algorithm Program Block It is not intended for live usage because consistency check takes a long time and consumes a lot of bandwidth between ICSU units It basically calculates the checksums locally and then only compare them between ICSU s which would dramatically reduce the execution time There is no need to transfer the large amount of data between units because the checksum calculation is efficient and does not take long time to calculate Consistency check procedure e Consistency check can be started with a new service terminal extension e Service terminal extension sends start message to Handover Control Algorithm Master process in given ICSU unit HC master in this ICSU unit reads through all other ICSU units and compares all data of all ICSU units against its own memory e If there are any errors HC master writes to ICSU computer log e Finally HC master acknowledges to Service terminal extension with the status only 5 3 2 Formatted printout of the RNW network topology Problem Definition In module testing it is very hard and slow to get an understandable view of the network topology which is present in some old regression test set or even in Functional Testing Because it is needed to open hundreds of network modification messages in module testing environment memorize the object id s and try to build
21. vendor specific algorithm 2 UE measures signal power of GSM Typically 1 second of frequencies in the neighbourlist measurements needed to average fading out 3 RNC commands the UE to decode BSIC of the best GSM candidate On average takes 1 second 4 RNC sends handover command to the UE Figure 18 Inter system handover procedure 4 pp 256 The inter system measurements are not active all the time but are triggered when there is a need to make intersystem handover The measurement trigger is a Radio Network Controller RNC vendor specific algorithm and could be based for example on the quality block error rate BER or on the required transmission power When the measurements are triggered the User Equipment UE measures first the signal powers of the GSM frequencies on the neighbour list Once those measurements are received by RNC it commands the UE to decode the BSIC base station identity code of the best GSM candidate When the BSIC is received by RNC a handover command can be sent to the UE The measurements can be completed in approximately 2 seconds 4 pp 255 26 The RNC recognises the possibility of Inter System Handover ISHO based on the configuration of the radio network neighbour cell definitions and relevant control parameters In case the second system is a GSM system the decision algorithm of the ISHO from GSM to WCDMA is located in the GSM Base Station Controller BSC From the viewpo
22. Algorithm Program Block interactions eee 61 Figure 32 Database Consistency Check fxs acsaysesczeresdsntonesectcerpansucateeestaaeesateuieeptanad 63 Figure 33 Actions when inconsistency is identified 2 0 0 0 eeeeseeeeeeseneeeeeeeeneeeeeees 65 Figure 34 Transition from log file to network topology table eee eeeeneeeeeeeees 69 Figure 35 Example for missing Neighbour Cell Definitions and Handover fail 70 List of Tables Table 1 First Generation Networks 3 pp 2 4 ait niin darieseiinnuiten niin danadess 4 Table 2 3GPP Release History in a nutshell 5 eee eeesnneeeeeceeeeeeeeenneeeeeeeees 10 Table 3 Formatted printout of the RNW network topology cccccccceeeeseeestteeeeeeeees 68 XV Key Concepts GSM 2 Generation Radio Access Network technology which is standardized by European Telecommunications Standards Institute It uses FODMA and TDMA as radio access method and at the backbone it uses digital circuit switching BSC Base Station Controller manages radio resources for Base Stations in GSM architecture RNC RNC stands for Radio Network Controller which is defined with UTRA 3G specifications The key functions of the Radio Network Controller RNC are management of terrestrial channels management of radio channel configurations in the Radio Access Network RAN radio resource management telecom functionality transmission amp transport features and maintenance amp opera
23. CDMA Mobilite Sorun Giderme al malar ve yile tirmeleri Derecesi B l m Haberle me M hendisli i Y ksek Haberle me ve A leti imi B l m Lisans Program Denet i Prof Jyri H m l inen Okutman Jukka Valtanen M Sc Eng zet Hareketlilik geni bant kod b lmeli oklu eri im WCDMA teknolojisindeki en nemli ba ar alan d r Kesintisiz hareketlili i korumak i in Radyo Kaynaklar Y netim algoritmalar a y netiminde ok nemlidir Eri im Kontrol Y k Kontrol Paket Zamanlay c s Kaynak Y neticisi ve G Kontrol algoritmalar ile birlikte H creler Aras Ge i Kontrol algoritmalar y ksek kaliteli kesintisiz bir ileti imdem sorumludur Bu algoritmalar Radyo ebeke Kontrol r yaz l m nda yer al r Yaz l m geli tirme s recinde farkl yaz l m program bloklari aras nda s k nt lar olabilir Yaz l msal sorunlar d nda radyo ebeke planlama sorunlar donan m sorunlar ve kullan c ekipman yla ilgili sorunlar olabilir Bu sorunlar n deneyimli Ar Ge m hendisleri taraf ndan analiz edilmesi gerekir Genellikle k k nedenin ne oldu unu arastirip ortaya karmak kolay de ildir Bu nedenle sorun takip ve giderme ara lar yaz l m geli tirmede hayati bir rol oynar Bu tez Nokia Siemens Networks irketi WCDMA Yaz l m Kontrol Platformu H creler Aras Ge i Kontrol Algoritmalar tak m ndaki mevcut sorun takip ve g
24. G John Wiley amp Sons 2004 Collins D Smith C 3G Wireless Networks 1st ed McGraw Hill Professional Publishing 2001 Korhonen J Introduction to 3G Mobile Communications 2nd ed Artech House Massachussets USA 2003 Holma H Toskala A WCDMA for UMTS Radio Access for Third Generation Mobile Communications 3rd ed John Wiley amp Sons 2004 3GPP 3GPP Releases http www 3gpp org releases accessed July 6 2011 Dalman E Parkvall S Sk ld J Beming P 3G Evolution HSPA and LTE for Mobile Broadband st ed Academic Press 2007 Tapia P Liu J Feuerstein M J HSPA Performance and Evolution A Practical Perspective Wiley 2009 Holma H Toskala A HSDPA HSUPA for UMTS High Speed Radio Access for Mobile Communications John Wiley amp Sons 2006 Holma H Toskala A LTE for UMTS Evolution to LTE Advanced 2nd ed Wiley amp Sons 2011 Laiho J Wacker A Novosad T Radio Network Planning and Optimisation for UMTS John Wiley amp Sons 2006 3GPP TSG RAN 3GPP Specification 25 922 Radio Resource Management Strategies http www 3gpp org ftp Specs html info 25922 htm accessed July 6 2011 3GPP 3GPP Specification 25 331 Radio Resource Control RRC Protocol Specification http pda etsi org exchangefolder ts_125331v051100p pdf accessed July 6 2011 Nokia Siemens Networks Internal Document Radio Network Controller Softwar
25. Global Positioning System Admission Control Acknowledgement Adjacent Detected Cell Adjacent GSM Cell Adjacent Inter Frequency cell Adjacent Intra Frequency cell Access Link Control Application Part Advanced Mobile Phone Service Active Set Active Set Update American Telephone and Telegraph Advanced TDMA Mobile Access Base Station Colour Code Broadcast Control Channel Bit Error Rate Block Error Rate Bandwidth on Demand Base Station Controller Base Station Identity Code Base Station Subsystem Base Transceiver Station Radio Telephone Network C Code Division Multiple Access Centralized Functions and services in Control Plane Cell Global Identification Cell Identifier Cell Individual Offset Compressed Mode CN CODIT CPICH CRNC CSCP CSUP DCCH DCH DL DMCU DMPG DPCCH DPCH DPDCH DRNC DS CDMA DSCR E DCH EDGE EHU EITP ETACS ETSI FCC FDD FDMA FM FRAMES GERAN GGSN GMSC GMSK GPRS GSM viii Core Network Code Division Testbed Common Pilot Channel Controlling Radio Network Controller Cell Specific functions and services in Control Plane Cell Specific functions and services in User Plane Dedicated Control Channels Dedicated Channel Downlink Data and Macro diversity Combining Unit Data and Macro Diversity Processor Group Dedicated Physical Control Channel Dedicated Physical Channel Dedicated Physical Data Channel Drifting Radio Network Controller Direct Sequence Code Division Multiple A
26. Iu interface problems e Software related issues o New features o New set of configuration parameters o Software bugs Investigation of handover related problems is quite often very time consuming Because handover is the basic state of the call thus handover problems can cause many kind of other problems and it has to be investigated in detail 13 There are many enhancement opportunities for the troubleshooting process that is related with handover problems For this thesis work some major ones were studied and analyzed in the following sub chapters 5 3 41 Investigation of large ICSU files Problem Definition Amount of information that is needed to analyze handover problems can be very huge ICSU log files parameter data and counter data Thus it would be good to have some tool which can be configured to search certain patterns which indicate some certain problems For example statistical data of Handover Control Algorithm initiated channel type switch requests and serving cell changes Furthermore the tool can provide summarized statistics by using cell based filtering Useful information related to channel type switch requests and serving cell changes would be e Number of requests e Trigger cause for the request e Intra frequency measurement reports from UE e Handling Events 1A and 1C e Target cell e Number of ACKs for the request e Number of NACKs for the request e Failure cause of the request That inform
27. LR Home Location Register is a database located in the user s home system that stores the master copy of the user s service profile MSC VLR Mobile Services Switching Centre Visitor Location Register is the switch MSC and database VLR that serves the UE in its current location for Circuit Switched CS services GMSC Gateway MSC is the switch at the point where UMTS PLMN is connected to external Circuit Switched networks SGSN Serving GPRS General Packet Radio Service Support Node functionality is similar to that of MSC VLR but is typically used for Packet Switched PS services GGSN Gateway GPRS Support Node functionality is close to that of GMSC but is in relation to PS services 14 2 33 WCDMA FDMA Hybrid FDMA TDMA Guard Guard Guard Guard Guard Guard Fi time time time time time time me Frequency channel 5 Frequency Guard band Guard band Frequency channel 4 Guard band Frequency channel 3 Frequency Guard band channels Frequency channel 2 Guard band Frequency channel 1 Guard band Frequency l Frequency Z S awig awn pieng p301s w L awn peng ew pieng gjs wL gos owl awy peng 301s oun awy peng TDMA Time CDMA Time Figure 8 FDMA TDMA Hybrid FDMA TDMA and CDMA 3 pp 26 27 WCDMA is a wideband Direct Sequence Code Division Multiple Access DS CDMA system
28. Management algorithms 12 Maximization of the commonalities in the handling of packet switched and circuit switched data with a unique air interface protocol stack and with the use of the same interface for the connection from UTRAN to both the PS and CS domains of the core network Maximization of the commonalities with GSM when possible Use of the ATM transport as the main transport mechanism in UTRAN Use of the IP based transport as the alternative transport mechanism in UTRAN from Release 5 onwards 2 2 1 UTRAN Elements Figure 7 UTRAN architecture extended 4 pp 76 The UE consists of two parts The Mobile Equipment ME is the radio terminal used for radio communication over the Uu interface The UMTS Subscriber Identity Module USIM is a smartcard that holds the subscriber identity performs authentication algorithms and stores authentication and encryption keys and some subscription information that is needed at the terminal 13 UTRAN also consists of two distinct elements The Node B converts the data flow between the Jub and Uu interfaces It also participates in radio resource management The Radio Network Controller RNC owns and controls the radio resources in its domain the Node B s connected to it RNC is the service access point for all services UTRAN provides to the Core Network for example management of connections to the UE The main elements of the Core Network are as follows H
29. P AALTO UNIVERSITY A School of Electrical Engineering E Department of Communications and Networking Serkan Kangal WCDMA Mobility Troubleshooting Studies and Enhancements Master s Thesis Espoo September 30 2011 Supervisor Prof Jyri H m l inen Instructor Jukka Valtanen M Sc Eng ii AALTO UNIVERSITY ABSTRACT OF MASTER S THESIS School of Electrical Engineering Department of Communications and Networking Author Date Pages Serkan Kangal 30 09 2011 88 Title of thesis WCDMA Mobility Troubleshooting Studies and Enhancements Degree programme Department Communications Engineering Department of Communications and Engineering Supervisor Prof Jyri H m l inen Instructor Jukka Valtanen M Sc Eng Abstract Mobility is the key success area in WCDMA technology To maintain seamless mobility Radio Resource Management algorithms are essential in network management Together with Admission Control Load Control Packet Scheduler Resource Manager and Power Control algorithms Handover Control algorithms are responsible for high quality seamless communication These algorithms take place in the Radio Network Controller software In software life cycle there can be challenges related with different software program blocks Other than software problems there can also be radio network planning problems hardware problems and user equipment related problems Those issues have to be ana
30. SAS SC FDMA SEB SFU SGSN SHO SIR SITP SRNC SRNS SWU SYB TACS TBU TDD TDMA UARFCN UE UER UL UMTS USCP USUP USIM UTRAN VAS xi Radio Resource Control Radio Resource Management Received Signal Code Power Resource and Switch Management Unit Real Time Receive Transmit Service Area Broadcast Service Access Point Stand Alone Serving Mobile location Centre Single Carrier Frequency Division Multiple Access Service Block Switching Fabric Unit Serving GPRS Support Node Soft Handover Signal to Interference Ratio Signalling Transport Plane Serving Radio Network Controller Serving Radio Network Subsystem Switching Unit Ethernet System Block Total Access Communications System Timing and Hardware Management Bus Unit Time Division Duplex Time Division Multiple Access UTRA Absolute Radio Frequency Channel Number User Equipment UE Specific Radio Resources Uplink Universal Mobile Telecommunications System UE Specific functions and services in Control Plane UE Specific functions and services in User Plane UMTS Subscriber Identity Module UTMS Terrestrial Radio Access Network Value Added Services VLR VOIP WCDMA WDU WTDMA xii Visitor Location Register Voice over IP Wideband Code Division Multiple Access Winchester Drive Unit for OMU Wideband Time Division Multiple Access xiii List of Figures Figure 1 Mobile Evolution 1 pp Al ate ce aia ae a 3 Figure 2 European research prog
31. The functionality is called the switchover The switchover is a procedure which provides fast recovery from a malfunction of a computer unit The switchover requires that the spare unit is available to take over the functionalities of the working unit without delays In a switchover procedure all content of all critical variables files time supervisions buffers and utility libraries need to be copied into the spare unit Critical information is information which needs to be precisely identical in the working and in the spare unit in order for a process to function correctly The copying process is called a warming process 15 47 Different customers need different services Usually there are different variations of the software package available Because of the modularity a version update of a software component or an addition of a software component is relatively easy This requires efficient version control on a component level as well as on a software package level 15 4 3 3 Service model architecture The service model means that when executing a task a process may delegate parts of the task to other processes What needs to be done defines the services that the other process needs to provide The whole system can be seen as a network of responsibilities and services The services become an interface to the process and the outside world sees only the service interfaces 13 pp 40 The service model SW is divided into three le
32. a mental image of the relations between them The best way is to draw it on a piece of paper In practice this makes re using or updating RNW configurations in existing module test projects very hard It is practically impossible to know what you can modify without breaking an existing test case Existing solution for the problem No present solution at all It would be very beneficial to have this feature Live network needs amp Internal testing needs A topology figure table has to be drawn by the tool according to collected modification messages 68 Implementation No need to have new functions or data types in Handover Control Algorithm Program Block the data will be stored and processed by an external tool Proposal Handover Control Algorithm Program Block messages have to be collected and then processed according to relations between cells After data collection required radio network topology can be drawn A quick sketch can be seen below displaying object identifiers with some of the key parameters BTS id Defines the identification number for the Base Transceiver Station WCEL id Identifies a WCEL unambiguously within a RNC ADJS id Defines the identification of intra frequency adjacent cell ADJI id Defines the identification of inter frequency adjacent cell ADJG id Defines the identification of GSM adjacent cell BTS id WCEL id CEL id BTS id WCEL id ADJI id WCEL id Table 3 Format
33. ation can be collected from investigated ICSU logs by searching following messages e Handover failure related messages ICSU messages sent received by Handover Control Algorithm Program Block e Handling of Event 1A Cell Addition e Handling of Event 1C Cell Replacement e Call release reasons for possible call drops 74 Existing Solution for the problem The ICSU files are analyzed with EMIL manually which takes a lot of time Desired information is visible also from statistics but that data is sometimes difficult to get from customer and also difficult to analyze By getting the information directly out from the ICSU data would be a good advantage For a better solution provided by this tool detailed information can be collected from ICSU logs and processed or demonstrated in desired way Live network needs amp Internal testing needs Condensed information could be useful in numerical format and also in some graphical format For example e Frequency of requests e Number of requests per trigger cause e Number of ACKs and Number of NACKs with specific failure cause e The success and failure ratio on cell level e How many requests from a certain cell and how many NACKs ACKs from a certain cell and BTS The information would be useful to get on cell level and on BTS level Implementation No need to have new functions or data types in Handover Control Algorithm Program Block the values will be stored and processed
34. bout this approach is that the results are not obtained as quickly as they are needed required data has to be provided correctly from customer s network Also analyzing that data can be a time consuming task Live network needs The tool has to create alarms or warnings for missing neighbour cell definitions The tool has to have ability to check Cell based IMSI based RNC based neighbour cell lists and compare the results within Detected Cell s list Internal Testing I amp V MT needs The tool has to create alarms or warnings for missing neighbour cell definitions The tool also has to provide debugging features for missing neighbour cell definitions and measurements The tool has to have ability to check Cell based IMSI based RNC based neighbour cell lists UE s Detected Cell list as well Implementation Additional functions or features to indicate that there is a problem in neighbour cell definitions might be needed Comparison between ADJD Detected adjacent cells and neighbour cell list might be needed Testing new features New features have to be tested by forcing system to have missing neighbour cell definitions Proposals Majority of the comparison and analyzing code for this tool can be located inside Handover Control Algorithm and only results passed to presented by post processed by the tool In this case newly implemented software part requires access to the network related information that is known
35. by Handover Control Algorithm for example the neighbour cell configurations and data counters After that the tool has to check the measurement reports that are done by UE as detected cells And according to decision algorithm it can inform operator about missing or wrongly configured neighbour cell definitions For this enhancement it is important to have detected cell reporting feature in working mode 12 5 3 4 Handover Related Troubleshooting Mobile Operators are monitoring their networks in terms of KPIs and customer complaints According to their business types they focus on certain KPIs and most of the time they calculate their own KPIs by using the default counters Furthermore vendors are also monitoring their customers in terms of certain KPIs The KPIs listed below are important to recognize the problems related with mobility Number of Call Drops Handover success rate Number of Handover attempts Change of average active set size increase decrease Average Ec No Number of IFHO Number of ISHO Number of SHO Depending on those indications the root cause of a problem can be e Configuration problems o Missing neighbour cell definitions o Wrong measurement control parameters o Wrong Jur Ju parameterization e Problems caused by other network elements o UE specific problems o Problems between RNCs Jur interface problems o Problems with BTS Jub interface problems o Problems with Core Network
36. by the tool Proposals ICSU logs have to be collected and then processed in terms of important values to report After doing required calculations condensed values can be reported in table or graphic format Those calculations can be done by using EMIL scripts and those scripts can be saved as an EMIL profile that can be used later as well 5 3 4 2 SHO KPI Problems Problem Definition As it is mentioned earlier KPIs have importance on indicating problems about the network But time to time there can also be problems about the KPIs itself Besides the default KPI values operators can have their own specific KPIs to monitor their network With a new software release to the network elements there can be a change in the KPIs by 1 2 due to many reasons such as new feature activations required changes to RRM parameter adjustments After software baseline upgrades there can be KPI problems which also affect handover processes 75 Existing Solution for the problem Currently the problem is investigated by analyzing the logs manually to check which parameter is calculated wrongly or configured wrongly Live network needs amp internal testing needs Internally correct values of the KPIs have to be calculated and compared to identify the problem This feature can also be provided to the field engineers or operators upon request Implementation A new EMIL profile can be created with embedded KPI calculations Message monitori
37. ccess Detected Set Cell Reporting Enhanced Dedicated Channel Enhanced Data Rates for Global Evolution External Hardware Alarm Unit External Interface functions in Transport Plane Extended Total Access Communications System European Telecommunications Standards Institute Federal Communications Commission Frequency Division Duplex Frequency Division Multiple Access Frequency Modulation Future Radio Wideband Multiple Access System GSM EDGE Radio Access Network Gateway GPRS Support Node Gateway Mobile Services Switching Center Gaussian Minimum Shift Keying General Packet Radio Services Global System for Mobile Communications HC HHO HLR HO HSCSD HSDPA HSUPA HSPA ICSU I HSPA I amp V IFHO IMS IMSI IS 95 IS 136 ISHO LAC LC LCS LTE MAC MBMS MCC ME MEHO MIMO MNC MRC MSC MT MXU NACK NBAP iX Handover Controller Hard Handover Home Location Register Handover High Speed Circuit Switched Data High Speed Downlink Packet Access High Speed Uplink Packet Access High Speed Packet Access Interface Control and Signalling Unit Internet High Speed Packet Access Integration and Verification Inter Frequency Handover IP Multimedia Subsystem International Mobile Subscriber Identity Interim Standard 95 for CDMA Interim Standard 136 for Digital AMPS Inter System Handover Location Area Code Load Control Location Services 3GPP Long Term Evolution Medium Access Control Multimedia Broadcast Multicast Servic
38. cts in each object class and report back to the tool by using the counters Also the number of received updates can be stored as counters which can help to investigate the problems in Radio Network Manager update mechanism E g how many add modify delete attempts have been done As an additional feature date and time of the last Radio Network Manager update can be stored in Handover Control Algorithm and printed out by the tool when requested If this procedure is followed full parameter check can create additional traffic in the live network and take a long time To make this procedure efficient e Consistency check can be limited to specific ICSU s e Consistency check can be limited to specific object class e Consistency check can be limited to specific object e Consistency check can be done in a specific time and once in a day that will not affect the network e g midnight Another approach can be comparing the parameters between two or more ICSU s without sending any query to RNC RNW Database Library But result may not be satisfying because the comparison will not be done with the raw data 65 Rene ae 3 Create Alarms Warnings Troubleshooting Give Diagnostic Info Force Parameter Update nS s lii a RNW Database Database Handover Manager Library Control Hand Process aa RNW Manager Handover Control Master Process Figure 33 Actions when inconsistency is identified Acc
39. deployment handovers to GSM were needed to provide continuous coverage and handovers from GSM to WCDMA can be used to lower the congestion loading in GSM cells 4 pp 254 When the coverage areas of WCDMA and the neighbouring system overlap each other an Inter System Handover ISHO can be used to control the load between the systems 10 pp 214 When the traffic in WCDMA networks increases it is important to have load reason handovers in both directions The inter system handovers are triggered in the source RNC BSC and from the receiving system point of view the intersystem handover is similar to inter RNC or inter BSC handover The handover algorithms and triggers are not standardised 4 pp 254 Handover WCDMA GSM for coverage extension Handover GSM WCDMA for capacity extension Figure 17 Inter system handovers between GSM and WCDMA 4 pp 255 29 In a practical example speech connections can be handed over to a neighbouring second generation 2G system and data connections handled within the WCDMA system Inter System Handover ISHO is a Hard Handover HHO and it causes temporary disconnection of the Real Time RT Radio Access Bearer RAB When an RT RAB is handed over from one system to another the Core Network CN is responsible for adapting the Quality of Service QoS parameters included in the RAB attributes according to the new system 10 pp 214 measurements with compressed mode
40. ding ICSU s In addition to pointing that there is a problem the tool can offer a solution to the problem It can be user oriented or automated After identifying the parameter inconsistency the tool can force ICSU s to ask for a new set of parameters This procedure will also create additional network load so the options can be re reading all the parameters a specific class of parameters or a specific parameter automated or inter active with user s choice Reading Source is another decision point It can either be from RNW database or from another ICSU s RNW manager initiated reading has to be analyzed in terms of feasibility by R amp D engineers 3 Give diagnostic information Load time Handover Control Algorithm Program Block can remember the start and end time of RNW database loading in unit or system start up and report back to tool when asked Average DB op time The program block can calculate the average time that it takes to perform one RNW database library call and report back to tool when asked Load source The program block can remember the number of reads which it performed from RNW database library or different ICSU s report back to tool when asked Number of failures The program block could calculate the number of failures retries it had to do when loading the database corrupted data from RNW database library error status from RNW database library report back to tool when asked 67 During
41. ds Committee T1 Telecommunications T1P1 China The China Wireless Telecommunication Standard Group CWTS ETSI Members ARIB Members TTA Members TIP1 Members TTC Members Figure 3 3GPP organizational partners 4 pp 67 CWTS Members In 3GPP four different technical specification groups TSG were set up e Radio Access Network TSG e Core Network TSG e Service and System Aspects TSG e Terminals TSG UTRA air interface specification was produced by the Radio Access Network TSG Release 99 UMTS specifications from ETSI were identical to the Release 99 specifications produced by 3GPP During 2000 further work on GSM evolution was moved from ETSI and other forums to 3GPP including work on GPRS and EDGE A new technical specification group TSG GERAN was set up for this purpose 4 pp 68 Within these groups the one most relevant to the WCDMA technology is the Radio Access Network TSG RAN TSG which has been divided into four different working groups Radio Access Network Technical Specification Group ITU AdHoc Architecture Radio ITU Activity and Performance Co ordination Interfaces and RF Parameters Figure 4 3GPP RAN TSG Working Groups 4 pp 68 As mentioned earlier the studies of various participating organisations were merged into a single standard and then the detailed parameters for the first full release Release 99 of UTRA from 3GPP finalised in 1999 In 3GPP the next version of
42. e Architecture Specification NSN 2010 84 14 Ilama J Master s Thesis Functional Regression Testing and Test Automation in a 3G Network Element Platform Environment Helsinki University of Technology Espoo 2010 15 Silander S DX Aapinen Edita Oy 1999 16 H rk nen P Master s Thesis Static Memory Optimization of Handover Control Helsinki Metropolia University of Applied Sciences Espoo 2010 85 8 Appendixes 8 1 Data types 8 1 1 ha3_rnw_parameter_query_s message rak_create_ha3_adjd_cell_s RNW Manager hand process sends this message to Handover Control Algorithm HC master process to notify that one new additional intra frequency adjacent cell to specified WCDMA cell has been created into the RNW RNC database RNW Manager hand process gt HC master process WCEL ID WCDMA cell identifier of cell under which the new intra frequency adjacent cell is created Identifies a WCEL unambiguously within a RNC HA3_ADJD_PARAM Additional adjacent cell parameters needed by Handover Control Algorithm Program Block In ha3_adjd_t data type adjd_id defines the identification of ADJD Additional Intra Frequency ADJ utran_cell_id defines the UTRAN cell identifier identifies neighbouring cell uniquely within UTRAN This one is used internally in RNC rak_create_ha3_adjg_cell_s RNW Manager hand process sends this message to HC master process to notify that one new GSM adjacent cell to specified WCDMA ce
43. e Mobile Country Code Mobile Equipment Mobile Evaluated Handover Multiple Input and Multiple Output Mobile Network Code Maximal Ratio Combining Mobile Services Switching Centre Module Test Multiplexer Unit Negative Acknowledgement Node B Application Part NCC NEHO NFC NMT NodeB NPGE NPS1 NRT NTT O amp M ODMA OFDMA OMS OMU Qos P CPICH PC PDC PLMN PRB PS R amp D RAB RAC RACE RAN RANAP RAT RLC RNC RNS RNSAP RNW Network Colour Code Network Evaluated Handover Near Field Communications Nordic Mobile Telephony Base Transceiver Station in UMTS Architecture Network Processor Interface Units Gigabit Ethernet Network Processor Interface Unit STM 1 Non Real Time Nippon Telegraph and Telephone Operation amp Maintenance Opportunity Driven Multiple Access Orthogonal Frequency Division Multiple Access Operation and Maintenance Server Operation and Maintenance Unit Quality of Service Primary Common Pilot Channel Power Control Personal Digital Cellular Public Land Mobile Network Program Block Packet Scheduler Research and Development Radio Access Bearer Routing Area Code Research of Advanced Communication Technologies in Europe Radio Access Network Radio Access Network Application Part Radio Access Technology Radio Link Control Radio Network Controller Radio Network Subsystem Radio Network Subsystem Application Part Radio Network RRC RRM RSCP RSMU RT RX TX SAB SAP
44. e U S as an experiment Then with the development of frequency modulation FM mobile communications became more reliable during World War II The development continued after the war and it started to be used in big cities of U S But those systems had limited capacity and inefficient transmission methods 2 pp 3 After multiple trials technology evolved to a level that it could be used as a commercial product In 1978 American Telephone amp Telegraph AT amp T implemented a Federal Communications Commission FCC authorized trial system in Chicago After analyzing the results of the trial system for a couple of years AT amp T got the licence for Advanced Mobile Phone Service AMPS A commercial mobile network was first deployed in Chicago and the other big cities followed AMPS was operating in 800 MHz band 2 pp 3 At the same time in Japan Nippon Telegraph and Telephone NTT started operating their AMPS network in Tokyo 3 pp 1 In 1980 s Nordic countries launched their Nordic Mobile Telephony NMT450 network which was using 450 MHz band in the following years it was developed to use 900MHz band After AMPS and NMT the British launched a new technology in 1985 which was Total Access Communications System TACS 2 pp 3 There were also other technologies developed but widely used technologies were AMPS NMT and TACS System Countries NMT 450 Andorra Austria Belarus Belgium Bulgaria Ca
45. e threshold plus an optional hysteresis value 36 Event 1F A P CPICH becomes worse than an absolute threshold A report is triggered when a new cell plus its cell individual offset becomes worse than an absolute threshold minus an optional hysteresis value 3 3 3 2 Time to trigger Mechanism The abundance of possible neighbouring cells together with the variety of triggering events could result in quite frequent reporting To protect the network from an excessive signalling load each of the reporting events can be connected with a timer Only if the measurement criteria have been fulfilled during the whole period until the timer expires is the event reported to the network Figure 22 shows an example of the time to trigger mechanism in case of Event 1A On the first two occasions when the event occurs no report is triggered since P CPICH 3 does not stay within the reporting range for a long enough time Only the third occurrence triggers the reporting of Event 1A 10 pp 219 P CPICH EJlo P CPICH 1 Addition ve P CPICH 2 P CPICH 3 Addition Time Event 1A Event 1A Reporting event 1A Time Figure 22 Time to trigger Mechanism for Event 1A 10 pp 219 3 3 3 3 Event triggered Periodic Reporting Reporting one of the above mentioned events typically results in an active set update However if the active set update cannot take place owing to lack of capacity or hardware resources for example
46. ecture 13 pp 38 mcRNC As it is seen on Figure 26 the general structure of the SW architecture remains similar to that of cRNC but the notable differences are in the removal of OMS as a unit of RNC and the change of platforms and middleware that support the new hardware and Linux OS Applications RNC Application Software Switching Platform Software Platform Figure 26 mcRNC SW architecture 13 pp 39 46 4 3 2 SW Architecture The essentials of the software architecture solutions of the RNC have been the following attributes e modular system e communication e redundancy e variations The software of the RNC consists of various independent software components such as process families libraries and files The software is very modular and hence easier to modify and develop than a large monolithic entity 15 The software components are loosely coupled together Each component implements a functional entity which functions very independently On the other hand each component needs each other to form a system The RNC contains a message bus which provides a connection for different components in different physical locations 15 A real time system needs the work contribution of every component all the time Each computer unit is duplicated into two a working unit and a spare unit The working unit is the one which provides the services The spare unit is taken into use if the working unit malfunctions
47. eing read This procedure is next to impossible to arrange at customer premises To make it happen it is needed to have an experienced scripting or debugging person at the site but usually they are not available until the problem has already been escalated As a result a new monitoring interface is needed to detect locate diagnose a problem once it has occurred Internal Testing I amp V MT needs The tool has to create alarms or warnings for parameter inconsistencies The tool also has to provide debugging features for the problems in terms of queries messages and responsible functional units Implementation Additional functions features to indicate that there is a parameter inconsistency might be needed New interface for parameter update traffic might be needed reason for a new interface explained above New data types might be needed Example for data types and functions 63 Tool gt Handover Control Algorithm inquire counter data reset counter data and launch consistency checks If something implemented directly to Handover Control Algorithm Tool lt gt Radio Network Manager launch Radio Network data reload to Handover Control Algorithm Program Block If reloading not implemented to Handover Control Algorithm Tool lt gt RNC RNW Database Library inquiries If the interfaces already used by Handover Control Algorithm are not sufficient Testing new features New features have to be tested by forc
48. eports are always periodic The events triggering them are not part of the standards The RNC may initiate inter frequency and or inter system measurements in various circumstances for example 10 pp 221 e Average downlink transmission power of a radio link as it approaches its maximum power level e Uplink transmission power reaches a threshold or its maximum events 6A 6D see below e Quality deterioration report from uplink outer loop PC from the RNC e Quality deterioration report from the UE e Unsuccessful SHO branch addition procedure e Unsuccessful RAB setup e UE located within cell where SHO capability is restricted e UE located within cell where admitted user bit rate is lower than requested e Frequent SHOs cell size and UE speed do not match e Radio network recovery management initiates forced HO procedure 38 e UE located within an area where cell structure is hierarchical inter frequency e UE located within an area where hierarchical network structure is composed of WCDMA and GSM systems inter system only e IMSI based HO is needed e UE located within a cell with restricted intra system HO capability inter system only 3 3 3 7 UE Internal Measurements UE internal measurements can be divided into two groups The first group is used to indicate to the network the status of the UE transmit power The reports may be used by the RNC to trigger off inter frequency or inter system measurements The second group is the UE
49. er MCC and MNC o Cell Identifier CI e Location Area Code LAC e Routing Area Code RAC e UTRA Absolute Radio Frequency Channel Number UARFCN e Scrambling code of the P CPICH For a GSM neighbouring cell the following information is sent e Cell Global Identification CGI Mobile Country Code MCC Mobile Network Code MNC CGI MCC MNC LAC CI e BCCH frequency e Base Station Identity Code BSIC Base Station Colour Code BCC Network Colour Code NCC BSIC BCC NCC Neighbour Cell Search on Current Carrier Frequency In idle mode as well as in connected mode the UE continuously searches for new cells on the current carrier frequency If the UE detects a candidate cell that has not been defined as a neighbouring cell it has to decode the cell s BCCH to identify the cell before it can report the measured E Ig of the detected neighbouring cell to the RNC In this case the following Information Elements IEs are used to identify the undefined neighbouring cells the downlink scrambling code LAC and CI When reporting the measurement result the UE may or may not include this information in the measurement report 10 pp 215 31 3 3 2 Measurement Reporting Criteria Depending on the handover HO type mobile evaluated handover MEHO or network evaluated handover NEHO different measurement reporting criteria can be used The RNC may request the UE to execute and report the following different types o
50. es South Korea Hong Kong Japan Singapore and many other East Asian countries In South Korea especially this standard was widely used IS 95 networks are also known by the brand name cdmaOne 3 pp 4 2 1 3 Generation 2 5 From technological perspective 2G developments were made to overcome the 1G deficiencies but could not add any additional value to the network After solving the first generation problems operators would like to increase their network values by connecting their networks to the big ocean Internet For that purpose different standardization committees discussed different technology enhancements to increase the user bandwidth First technology that was used was High speed Circuit switched Data HSCSD it was circuit connection based and could not get much support from the handset manufacturers HSCSD was a good solution for real time services but when there is no traffic reserved resources will be idle which is a waste of money 3 pp 5 Then the General Packet Radio Services GPRS came to the market GPRS was suitable for non real time applications Throughput was increased by packet switched transmission Implementation of GPRS was not as easy as HSCSD additional hardware was needed for the radio network 3 pp 6 Another approach to increase the user bandwidth was to change the modulation method Enhanced Data rates for Global Evolution EDGE was developed by using eight phase shift keying 8PSK
51. f basic HO measurements e intra frequency measurements MEHO e inter frequency measurements NEHO e inter system measurements NEHO e UE internal measurements All HO measurement types are controlled independently of each other and are defined on a cell by cell basis with the exception of UE internal measurements which are partly controlled by parameters common to all cells under the same RNC Two or more HO measurement types can be active simultaneously e g intra and inter frequency measurements Typically in a RAN separate measurement parameter sets for RT and NRT bearers and for users applying HSDPA can be defined Control of the HO measurements is explained in detail in the following sections in connection with the relevant HO types 10 pp 216 3 3 2 1 Intra Frequency Handover Measurements The RAN broadcasts the measurement reporting criteria measurement parameters for intra frequency measurements on the BCCH When the criteria are fulfilled the UE reports the results of its measurements to the RNC The RNC in turn makes the HO decision If the ASU could not be executed the UE continues to measure the neighbouring cells but changes to periodic reporting of the results For this type of measurements the UE uses separate measurement reporting criteria transmitted to the UE 10 pp 216 3 3 2 2 _Inter Frequency and Inter System Handover Measurements Inter frequency and inter system measurements are both made only
52. face is for UE handover measurement Dedicated RRC process provides RRC protocol for dedicated radio connections HC hand receives UE handover measurement reports and also sends and receives UE handover measurement control messages via this interface 4 There are two interfaces towards UER UE Specific Radio Resources e Start of Handover Control algorithm UER requests HC master to start handover control algorithm HC hand for UE connection HC hand is always started in the same ICSU as the UER resides e Handover algorithm main interface This is an interface between UE specific Radio Resources UER and handover control algorithm in HC hand All UE specific control functions related to soft softer hard handovers serving cell change compressed mode activation and deactivation are handled through this interface e Handover Control Algorithm Program Block triggers DCH to HS DSCH channel switching and vice versa for not DCH 0 0 5 This interface is for serving RNC SRNC BTS measurement reporting HC hand receives dedicated BTS measurement reports in SRNC NBAP via this interface Control of dedicated BTS measurements is also performed through this interface 6 This interface is for drifting RNC DRNC BTS measurement reporting HA3 m initiates common BTS measurements and receives measurement reports from DRNC RNSAP via IUR control process HC hand initiates dedicated BTS measurements and receives dedicated BTS measurement
53. for missing Neighbour Cell Definitions and Handover fail There is an example radio network topology in Figure 35 At the beginning there are only BTS1 BTS2 and BTS3 Then a new BTS BTS4 is added by operator due to congestion but updating the neighbour cell definitions is forgotten If a call is started by a mobile user within the coverage area of BTS1 following a path through BTS1 gt BTS2 gt BTS4 gt BTS3 first handover occurs between BTS1 and BTS2 to maintain the call state When the user moves to the edge of BTS2 coverage area and gets the radio signals of BTS4 BTS4 is added to the active set As it enters to the coverage area of BTS4 there has to be a handover and the call has to be forwarded to BTS4 But the call is dropped because the neighbour cell definitions are missing at the responsible RNC Existing solution for the problem If missing neighbour cell definitions are known to be the cause of the problem then the collected data is analyzed with some effort and the determination is done which neighbouring cell definitions are missing After the data has been collected it can be with some effort analyzed and determined if which neighbouring definitions are missing Another method is to analyze the call 71 drop counters and try to solve why and where the call drops are happened In most of the cases it is found out that there is neighbour information missing from a cell located at the call drop area The problem a
54. g Experiences Serving to all 3GPP requirements radio network controller software includes millions of lines of code During the internal testing phase of the software there can be several bugs or missing features Bugs can also appear inside the verified versions of the software Vendors design tailor made software solutions for different operators and this differentiation also hardens the testing and troubleshooting process 5 1 Troubleshooting Approach for Mobile Networks In mobile networks problem solving for software or hardware problems has to be done by experienced senior engineers Each mobile network element is designed to inform its operators for errors or problems But operators are not always proficient to investigate complex situations Those situations need to be handled by vendor s own engineers In general troubleshooting is done in 4 steps e Fault Identification e Symptom Collection e Symptom Analysis e Fault Repair In Fault Identification engineers have to identify clearly what the problem is For this purpose vendors have developed some tools Common features of these tools e User Interface e Cell Status Reporting e Link Status Reporting Radio Transport Signalling e Key Performance Indicators KPI Threshold Monitoring e Alarm Monitoring e Alarm History Tracking e Problem prioritization e Process assessment e Counter analysis 58 In Symptom Collection engineers have to collect data for
55. gio Xm 1 W 10 logioMgest i 1 Rip Hyp 2 where Rip is the reporting range constant for event 1B sent from the RNC Moua is the measurement result of the cell leaving the reporting range C O q is the cell individual offset of the cell leaving the reporting range and H is the hysteresis parameter for Event 1B The hysteresis parameter together with the reporting range constant is usually called the drop window Event 1C A non active P CPICH becomes better than an active one A report is triggered when the equation below is fulfilled i e when a P CPICH that is not in the active set gets better than the worst P CPICH from the active set when the active set is full Used to replace the cell with the worst P CPICH 10 l09i0Mnew ClOvew 2 10 logioMinas ClOmas Hic 2 where Mmag is the measurement result of the cell in the active set with the lowest measurement result CIOmas is the cell individual offset for the cell in the active set that is becoming worse than the new cell and H is the hysteresis parameter for Event 1C The hysteresis parameter is usually called the replacement window Event 1D Change of best cell A report is triggered when any P CPICH in the reporting range becomes better than the current best plus an optional hysteresis value Event 1E A P CPICH becomes better than an absolute threshold A report is triggered when a new cell plus its cell individual offset becomes better than an absolut
56. grant HSDPA or HSPA for the user during user plane creation or that Handover Control Algorithm Program Block triggers user plane to DCH DCH allocation from HS D PA allocation which means again lower bit rates Another typical issue is Handover Control Algorithm Program Block serving cell algorithm does not work correctly and it is not able to keep the best active set cell as HS DSCH serving cell or it triggers CTS to DCH DCH instead of serving cell change Also serving cell change KPI is one which operators are keen and if there happens even 0 01 worsening in this KPI the operators start to complain And for this kind of KPI worsening it is very hard to find root cause without good statistical information Some kind of tool which could be used to collect statistical data of Handover Control Algorithm initiated channel type switch requests and serving cell changes would be useful when investigating large ICSU files from customer live networks Monitoring should be done cell based responsible cell and the target cell Useful information related to channel type switch requests and serving cell changes would be e Number of requests e Trigger cause for the request e Number of ACKs for the request e Number of NACKs for the request e Failure cause of the request T11 Existing Solution for the problem The ICSU files are analyzed with EMIL which takes a lot of time Desired information is visible also from statistics but that data is s
57. hapter 5 includes the troubleshooting experiences and introduces an existing troubleshooting tool called EMIL Then it depicts and analyzes existing challenges in Handover Control Algorithm Block Chapter 6 has conclusion statements about the thesis Chapter 7 includes the list of references and Chapter 8 includes the message details for a particular issue which will be analyzed in 5 3 2 The scope of this thesis work was decided with the NSN Control Plane Handover Algorithms team My prior knowledge about WCDMA was not deep enough to analyze the handover algorithm based problems so I started studying the Radio Resource Management fundamentals focusing on handover types In the second chapter I try to inform the reader about the short history of WCDMA and in the further chapters I try to focus the attention on Handover Algorithm analysis With the Handover Algorithms team we started with initial thesis meetings to define the scope of the work Then from different proficiencies analysis requests were gathered and problem specific small working groups were assigned After that thesis progress continued with weekly updates 2 WCDMA and HSPA Basics In this chapter a short history about 3G evolution and basics of WCDMA and HSPA will be presented 2 1 Evolution to 3G 2 1 1 1 Generation Figure 1 Mobile Evolution 1 pp 4 The first mobile telephony network was deployed in 1920 for the use of several police departments in th
58. hbour Cell Definitions For each cell in the UTRAN an own set of neighbouring cells must be defined in the radio network configuration database typically located in the RNC Since a neighbouring cell may be located in the same network on the same frequency on a different frequency or in any neighbouring Public Land Mobile Network PLMN the following neighbour lists need to be defined for each cell in case the corresponding HO needs to be supported 10 pp 215 e Intra frequency neighbour cell list The UE must be able to monitor at least 32 cells on the same WCDMA carrier frequency as the serving cell e Inter frequency neighbour cell list The UE must be able to monitor at least 32 cells on a maximum of two WCDMA carrier frequencies in addition to the serving cell s frequency e Inter system neighbour cell lists For each neighbouring PLMN an own list is needed In total a maximum of 32 inter frequency neighbours must be supported by the UE 30 The RAN broadcasts the initial neighbour cell list s of a cell in the system information messages on the BCCH Broadcast CCH In case a required ASU has been performed a new neighbour list is combined in the RNC based on the neighbour lists of the cells in the new active set and then is sent to the UE on the DCCH To identify a WCDMA neighbour cell this list includes the following information 10 pp 215 e UTRAN Cell Identifier o Global RNC identifier PLMN identifi
59. iderme z mlerini analiz etmekte ve bu ihtiya lar i in geli tirilmi z mler nermektedir Bu tezin bir sonucu olarak baz geli mi z mler uygulanmakta ve di er z mler i in analizler sa lanmaktad r Sorun giderme ara lar ve metodolojisinin geli tirilmesi bu tezin tamamlanmas ndan sonra yaz l m geli tirme ekibinde devam edecektir Anahtar Kelimeler WCDMA Radyo ebeke Kontrol r H creler Aras Ge i Preface This Master s thesis presents the work that was carried out under supervision of Professor Jyri H m l inen from Aalto University School of Electrical Engineering and under instruction of M Sc Jukka Valtanen from Nokia Siemens Networks This thesis work was performed at Nokia Siemens Networks premises in Espoo from January 2011 to September 2011 Acknowledgements I would like to thank to my employer for giving me the opportunity and necessary support for writing this thesis It would have been impossible to prepare this thesis without the guidance and support of my colleagues I would like thank to Kari Oskari Tony Maria Jari and my instructor Jukka I would also like to thank my supervisor professor Jyri H m l inen from Aalto University School of Electrical Engineering for his guidance during the thesis process After the clarification of the thesis topic by Nokia Siemens Networks he helped me in getting the process started and also thereafter gave me val
60. ignal code power RSCP for TDD e Downlink quality e g Transport channel BLER e Downlink signal measurements e g CPICH RCSP CPICH E No Pathloss e Distance e Change of service e Operation amp Maintenance intervention e Directed retry e Traffic load e Pre emption From Radio Network Controller point of view there are 4 different types of handovers e Intra System Intra Frequency Handover Soft Handover SHO e Inter System Handover GSM lt WCDMA e Intra System Intra Frequency Hard Handover e Intra System Inter Frequency Handover 3 2 1 Intra System Intra Frequency Handover Soft Handover SHO Soft Handover SHO is a general feature in wireless systems such as WCDMA in which neighbouring cells are operated on the same frequency When in Connected Mode the user equipment UE continuously measures serving and neighbouring cells cells indicated by the RNC on the current carrier frequency Periodically the UE compares the measurement results with HO thresholds provided by the RNC When the reporting criteria is fulfilled and UE sends a measurement report back to the RNC indicating the SHO presence The decision algorithm of SHO is located in the RNC Because of this measurement reporting SHO is a Mobile Evaluated Handover MEHO 10 pp 212 23 X A i Node B2 Figure 15 Soft Handover 3 pp 38 x gas Softer Handover A softer HO is an HO between two sectors of a cell From a UE s point of vie
61. in ja tehovalvonnan kanssa kanavanvaihtoalgoritmit vastaavat laadukkaan katkeamattoman yhteyden yll pidosta N m algoritmit on toteutettu radioverkko ohjaimen RNC ohjelmistossa Ohjelmiston elinkaaren aikana ohjelmiston eri osissa kohdataan erilaisia haasteita Ohjelmiston lis ksi ongelmia voi l yty my s radioverkon suunnittelusta verkkolaitteistosta tai p telaitteista Kaikkien n iden ongelmien analysointiin vaaditaan kokeneita R amp D insin rej eik ongelmien varsinaisen aiheuttajan l yt minen usein ole yksinkertaista T m n takia erilaiset vianetsint ty kalut ovat ohjelmistokehityksess ensisijaisen t rkeit T m diplomity analysoi jo k yt ss olevia vianetsint menetelmi NSN WCDMA Control Plane Handover Algorithm ryhm ss sek esitt erilaisia paranneltuja ratkaisuja n ihin menetelmiin T m n diplomity n tuloksena muutamia paranneltuja ratkaisuja toteutettiin ja muutamia muita ratkaisumalleja analysoitiin Vianetsint ty kalujen sek menetelmien kehitys jatkuu tarkastellussa ohjelmistokehitysryhm ss my s t m n diplomity n valmistumisen j lkeen Avainsanat WCDMA radio network controller handover iv AALTO N VERS TES Y KSEK L SANS TEZ ZET Elektrik M hendisli i Fak ltesi Haberle me ve A leti imi B l m Yazar Tarih Sayfa Serkan Kangal 30 09 2011 88 Tez Ba l Geni Bant Kod B lmeli oklu Eri im W
62. informed about the software architecture of RNC and Handover Control Algorithm Needs of R amp D engineers were discussed and a list for enhancement opportunities was decided during the meetings Then efficiency evaluation was done case by case basis to prioritize the cases for the thesis work duration Some enhancement cases were eliminated due to their complex analysis and implementation techniques After the study cases were determined individual meetings with the senior engineers took place on a weekly schedule Enhancement cases were studied with their problem statements existing solutions live network needs internal integration and verification needs implementation possibilities enhancement proposals and testing scenarios for new functionalities In Radio Network Database Parameter Consistency checking case different solutions are proposed for implementation see 5 3 1 for detailed analysis As a consequence of analysis reliable and efficient implementation was done for internal usage With the pace of the radio network technology evolution future networks are designed to be flexible in terms of network resources To maintain same configuration information databases in the network elements must be same in terms of common parameters For future studies this database consistency check feature can be added to the RNC software itself as an automated self check tool 81 In Formatted Printout of the RNW topology case implementati
63. ing the system to have inconsistent parameters When testing with real RNC it could be possible that after the RNW data is read from Operation and Maintenance Unit OMU during start up test program would send modified messages to Handover Control Algorithm in one ICSU to change the parameter values that have been read from database For simulating the corruption a test program maybe a version compiled with special flags can also be part of the tool itself Proposals The tool can check the parameters from different ICSU s and compare them with the ones that are read from RNW Manager or RNW Database Manager or RNW Database Library RNW Database Database Handover Manager Library Control Hand Process Handover Control Master Process RNW Manager Figure 32 Database Consistency Check 64 In a regular consistency check approach see Figure 32 1 Correct parameters have to be read from the RNW Database Library 2 A parameter query has to be sent broadcast to every ICSU 3 Received parameters from ICSU have to be compared with the ones in the database 4 The differences need to be reported This procedure should be enough to catch the missing or corrupted parameters but it does not detect possible excess objects which are still in Handover Control Algorithm but removed from RNW database To solve this problem there can be simple object counters Handover Control Algorithm can count the number of obje
64. int of the RNC an ISHO from GSM to WCDMA does not differ from the inter RNC HHO Correspondingly an ISHO from WCDMA to GSM does not differ from the inter BSC HO from the viewpoint of the GSM BSS As with inter frequency measurements the User Equipment UE must be either equipped with a second receiver or support Compressed Mode CM to execute inter system measurements 10 pp 214 3 2 2 1 Compressed Mode Intra frequency neighbours can be measured simultaneously with normal transmission by the UE using a RAKE receiver Inter frequency and inter system measurements however require the UE to measure on a different frequency This can be done by incorporating multiple receivers in the UE A second possibility that avoids receiver multiplicity is stopping the normal transmission and reception for a certain time period enabling the UE to measure on the other frequency 10 pp 223 WCDMA uses continuous transmission and reception and cannot make inter system measurements with a single receiver if there are no gaps generated in the WCDMA signals Therefore compressed mode is needed both for inter frequency and for inter system measurements 4 pp 255 Inter system handovers from GSM to WCDMA are initiated in GSM BSC No compressed mode is needed for making WCDMA measurements from GSM because GSM uses discontinuous transmission and reception 4 pp 258 27 1 2 3 4 5 TGPRC on ITG Pattern 2 Transmission Transmissi
65. ission Control When a radio resource related request is received in the RNC the admission control algorithm estimates the minimum radio resources required to provide the required quality of service determines whether these radio resources are available and if they are allocates them Failing this the request for radio resources is denied 4 pp 264 Load Control The main task of the load control algorithm is to measure the cell load and prevent the system from becoming overloaded Should this happen the load control algorithm returns the system both quickly and controllably to the normal load state defined during the radio network planning phase 4 pp 267 Packet Scheduler The packet scheduler takes care of scheduling radio resources for the best effort traffic in both the uplink and the downlink directions 4 pp 278 Resource Manager The main function of the resource manager is to allocate downlink spreading codes when the admission control entity or the packet scheduler requests this function The resource manager also optimizes the usage of the code tree in a cell 10 pp 244 21 Connection Based Algorithms Handover Control Handover control serves in two purposes Firstly it ensures that the user equipment is connected to the strongest cell at all times This helps to control the interference level in the network by minimizing the transmission power Secondly handover control supports user mobility by ensuring tha
66. itecture of Handover Control Algorithm Program Block and the interfaces to other program blocks are illustrated in Figure 29 Interfaces 1 amp 2 Handover Control Algorithm master uses the RNC RNW Database Library to read the relevant operator defined RNC RNW parameters RNC RNW Database Library in turn uses RNW Database Manager to perform the actual hand fast reads from the RNW Database Handover Control Algorithm HC master reads the relevant parameters at process start up and stores them to its internal data structures UE dedicated Handover Control Algorithm HC hand processes HC hand have access to these parameters via internal function interface If the operator changes these parameters in the RNC RNW database the Radio Network Manager sends a message including the modified parameters to Handover Control Algorithm HC master process RNC RNW Location NBAP Base station Database Based Services Protocol Resource Manager Library and Program Block Program Block Program Block Manager RRC Protocol Program eae Block Periodical RNW Measurement UE Radio Interface n Resources Program Block a Y Program Handover Handover Block Statistic Report Control Control Handler Algorithm Algorithm Hand Master UE specific Iur Interface o Problem istribute Monitoring Statistics sie Tool Mediator Mediator Program Block Outer Loop Power Control Figure 29 Handover Algorithms Program Block Diagram 53 3 This inter
67. ll has been created into the RNW RNC database RNW hand process gt HC master process WCEL_ID WCDMA cell identifier of the modified WCDMA cell Identifies a WCEL unambiguously within a RNC HA3_ADJG_PARAM GSM neighbour cell parameters needed by Handover Control Algorithm Program Block In ha3_adjg_t data type adjg_id defines the Identification of ADJG cell_id identifies a WCEL unambiguously within a RNC 86 rak_create_ha3_adji_cell_s RNW Manager hand process sends this message to HC master process to notify that one new inter frequency adjacent cell to specified WCDMA cell has been created into the RNW RNC database RNW hand process gt HC master process WCEL JID Cell id of the modified WCDMA cell HA3_ADJI_ PARAM Inter frequency neighbour cell parameters needed by Handover Control Algorithm Program Block In ha3_adji_t data type adji_id defines the identification of the ADJI and utran_cell_id defines the UTRAN cell identifier identifies neighbouring cell uniquely within UTRAN This one is used internally in RNC rak_create_ha3_adjs_cell_s RNW Manager hand process sends this message to HC master process to notify that one new intra frequency adjacent cell to specified WCDMA cell has been created into the RNW RNC database RNW hand process gt HC master process WCEL ID WCDMA cell identifier of cell under which the new intra frequency adjacent cell is created Identifies a WCEL unambiguously withi
68. lyzed by experienced R amp D engineers Usually it is not straightforward to investigate what is the root cause Because of this reason troubleshooting tools play a vital role in software development This thesis analyzes the existing troubleshooting solutions in NSN WCDMA Control Plane Handover Algorithm team and proposes enhanced solutions for those needs As a result of this thesis some of the enhanced solutions are implemented and analyses for the other solutions are provided Development of troubleshooting tools and methodology will continue in the software development team after the completion of this thesis Keywords WCDMA radio network controller handover troubleshooting iii AALTO YLIOPISTO DIPLOMITYON TIIVISTELMA S hk tekniikan korkeakoulu Tietoliikenne ja tietoverkkotekniikan laitos Tekij P iv ys Sivum r Serkan Kangal 30 09 2011 88 Ty n nimi WCDMA Mobility Troubleshooting Studies and Enhancements Tutkinto ohjelma Laitos Tietoliikennetekniikka Tietoliikenne ja tietoverkkotekniikan laitos Ty n valvoja Prof Jyri H m l inen Ty n ohjaaja Jukka Valtanen M Sc Eng Tiivistelm Mobiliteetti on yksi WCDMA teknologian menestyksen avaintekij ist Saumattoman liikkuvuuden yll pit miseksi radioresurssien hallinnan algoritmit ovat t rke ss roolissa verkon hallinnassa Yhdess p syvalvonnan kuormavalvonnan pakettiskedulerin resurssimanager
69. mation has to be collected stored and processed to create the network topology In the log messages required information is located under certain data types ha3_rnw_parameter_query_s message includes the desired information to build the network topology table The same signals are also used when database sends new updated parameters to Handover Control Algorithm Detailed information about the signals can be found in Appendix 8 1 1 Required messages to build the network topology in a nutshell are given below BTS id can be provided from rak_create_ha3_wcel_s signal s ha3_wbts_param_t data type wbts_id object WCELL id can be provided from rak_create_ha3_wcel_s signal s ha3_wcel_param_t data type wcell_id object ADJS id can be provided from rak_create_ha3_adjs_cell_s signal s ha3_adjs_t data type adjs_id object ADJI id can be provided from rak_create_ha3_adji_cell_s signal s ha3_adji_t data type adji_id object ADJG id can be provided from rak_create_ha3_adjg_cell_s signal s ha3_adjg_t data type adjg_id object 70 5 3 3 Missing neighbour cell definitions ADJ s Problem Statement In the radio resource planning phase some cell s neighbours are defined wrongly or with missing information UE s detected cells measurements are sent to RNC and the troubleshooting tool can be used to inform operator about the unlisted but detected adjacent cells Figure 35 Example
70. mbodia Croatia Czech Republic Denmark Estonia Faroe Islands Finland France Germany Hungary Iceland Indonesia Italy Latvia Lithuania Malaysia Moldova Netherlands Norway Poland Romania Russia Slovakia Slovenia Spain Sweden Thailand Turkey and Ukraine NMT 900 TACS ETACS Cambodia Cyprus Denmark Faroe Islands Finland France Greenland Netherlands Norway Serbia Sweden Switzerland and Thailand Austria Azerbaijan Bahrain China Hong Kong Ireland Italy Japan Kuwait Macao Malaysia Malta Philippines Singapore Spain Sri Lanka United Arab Emirates and United Kingdom AMPS Argentina Australia Bangladesh Brazil Brunei Burma Cambodia Canada China Georgia Guam Hong Kong Indonesia Kazakhstan Kyrgyzstan Malaysia Mexico Mongolia Nauru New Zealand Pakistan Papua New Guinea Philippines Russia Singapore South Korea Sri Lanka Tajikistan Taiwan Thailand Turkmenistan United States Vietnam and Western Samoa C NETZ Germany Portugal and South Africa Radiocom 2000 France Table 1 First Generation Networks 3 pp 2 2 1 2 2 Generation At the beginning the capacity was enough for the limited amount of subscribers but when the number of subscribers increased operators and vendors started to think on better technologies for mobile communications With this motivation different 2G technologies were developed in different countries
71. modify_ha3_vcel_param_s RNW Manager hand process sends this message to HC master process to notify that VCEL parameters have been modified
72. n Also HHO here means that IFHO causes temporary disconnection of the real time radio access bearers RT RAB and is lossless for non real time NRT bearers IFHO also enables handovers between separate layers of a multi layered cellular network e g a network consisting of macro and micro cells where the cell layers are using different carriers The radio access network handover controller RAN HC should support the following types of IFHO 10 pp 213 e intra Base Station BS HHO to control the load between carriers e intra 7 RNC HHO e inter RNC HHO 29 IF HO is a Network Evaluated Handover NEHO since its evaluation algorithm is located in the RNC The RNC recognises the possibility of an IFHO based on the configuration of the radio network frequency carrier allocation neighbour cell definitions cell layers etc When a UE is located where an IFHO is possible and needed the RNC commands the UE to start inter frequency measurements and to report the results periodically HO decisions are then made by the RNC based on those measurement results inter and intra frequency and relevant control parameters 10 pp 213 214 3 3 Handover Measurements Handover Measurements are important for the decisions that are derived by handover algorithms HO measurement reporting can be divided into the following stages 1 Neighbour cell definitions 2 Measurement reporting criteria 3 Reporting of measurement results 3 3 1 Neig
73. n a RNC HA3_ADJS_PARAM Adjacent cell parameters needed by Handover Control Algorithm Program Block In ha3_adjs_t data type adjs_id defines the identification of ADJS Intra Frequency ADJ utran_cell_id defines the UTRAN cell identifier identifies neighbouring cell uniquely within UTRAN This one is used internally in RNC rak_create_ha3_fmcg_s RNW Manager hand process sends this message to HC master process to notify that one new set of GSM measurement control parameters has been created into the RNW RNC database rak_create_ha3_fmci_s RNW Manager hand process sends this message to HC master process to notify that one new set of inter frequency measurement control parameters has been created into the RNW RNC database rak_create_ha3_fmcs_s RNW Manager hand process sends this message to HC master process to notify that one new set of intra frequency measurement control parameters has been created into the RNW RNC database 87 rak_create_ha3_hopg_s RNW Manager hand process sends this message to HC master process to notify that one new set of GSM handover path parameters has been created into the RNW RNC database rak_create_ha3_hopi_s RNW Manager hand process sends this message to HC master process to notify that one new set of inter frequency handover path parameters has been created into the RNW RNC database rak_create_ha3_hops_s RNW Manager hand process sends this message to HC
74. n be deployed by the network operator as a system option to increase capacity and or coverage 4 pp 49 PSTN Internet eh gt Core network P a gt l SESS gt 4 o a To other NodeBs Dedicated channels NodeB oe Figure 10 WCDMA radio access network architecture 6 pp 132 16 The chip rate of 3 84 Mcps leads to a carrier bandwidth of approximately 5 MHz DS CDMA systems with a bandwidth of about 1 MHz such as IS 95 are commonly referred to as narrowband CDMA systems The inherently wide carrier bandwidth of WCDMA supports high user data rates and also has certain performance benefits such as increased multipath diversity Subject to its operating licence the network operator can deploy multiple 5 MHz carriers to increase capacity possibly in the form of hierarchical cell layers The actual carrier spacing can be selected on a 200 kHz grid between approximately 4 4 MHz and 5 MHz depending on interference between the carriers 4 pp 47 WCDMA supports highly variable user data rates in other words the concept of obtaining Bandwidth on Demand BoD is well supported The user data rate is kept constant during each 10 ms frame However the data capacity among the users can change from frame to frame This fast radio capacity allocation will typically be controlled by the network to achieve optimum throughput for packet data services 4 pp 48 Furthermore WCDMA supports the operation of asy
75. nchronous base stations so that unlike in the synchronous IS 95 system there is no need for a global time reference such as a GPS Deployment of indoor and micro base stations is easier when no GPS signal needs to be received WCDMA employs coherent detection on uplink and downlink based on the use of pilot symbols or common pilot While already used on the downlink in IS 95 the use of coherent detection on the uplink is new for public CDMA systems and will result in an overall increase of coverage and capacity on the uplink 4 pp 48 2 4 HSPA NodeB GGSN UE App Server Uu lub lu ps Gn Gi I hes t i Internet RNC SGSN Figure 11 Network Diagram for HSPA traffic user plane 7 pp 28 17 High Speed Downlink Packet Access HSDPA was standardized as a part of 3GPP Release 5 with the first specification version in March 2002 High speed uplink packet access HSUPA was a part of 3GPP Release 6 with the first specification version in December 2004 HSDPA and HSUPA together are called High Speed Packet Access HSPA The first commercial HSDPA networks were available at the end of 2005 and the commercial HSUPA networks were available by 2007 8 pp 4 HSPA development history including LTE is illustrated in Figure 12 and HSPA Evolution is illustrated in Figure 13 3GPP schedule 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Commercial deployment Figure 12
76. near values of F I not the dB values 10 pp 217 34 P CPICH Ec lo P CPICH 1 P CPICH 2 P CPICH 3 P CPICH 4 Reporting of Event 1A Event 1E Event 1C Event 1D Event 1B Event 1F time Figure 21 Intra frequency Measurements 10 pp 219 For intra frequency measurement criteria the following reporting events are defined 10 pp 218 Event 1A A P CPICH enters the reporting range A report is triggered when the equation below is fulfilled 10 s logioMynew ClOnew NA gt W 10 logio X m 1 W 10 logioMpest i 1 z Ria Hyq 2 where Myew is the measurement result of the cell entering the reporting range C Oyew is the cell individual offset of the cell entering the reporting range M is a measurement result of a cell in the active set not forbidden to affect the reporting range N is the number of cells in the current active set not forbidden to affect the reporting range Moest is the measurement result of the strongest cell in the active set W is a weighting parameter sent from the RNC to the UE Rj is the reporting range constant for Event 1A sent from the RNC to the UE and H is the hysteresis parameter for Event 1A The hysteresis parameter together with the reporting range constant is usually called the addition window 35 Event 1B A P CPICH leaves the reporting range A report is triggered when the equation below is fulfilled 10 logioMoia ClO 1a Na lt W 10 lo
77. ng has to be triggered by Handover Control Algorithm Proposals KPIs are calculated from counters the raw data has to be read from counters and exact KPI values can be calculated from them An EMIL profile can be designed for this purpose But to achieve this Distributed Statistics Mediator s debug feature has to be turned on Furthermore Radio Resource Control Program Block is doing message monitoring for failure situations and dropped calls For a better investigation Handover Control Algorithm Program Block can trigger message monitoring via Radio Resource Control Master process and get the required logs The logs include the message monitoring between e UE Radio Resources Program Block lt gt Handover Control Algorithm Program Block e Radio Resources Control Program Block dedicated RRC protocol hand lt 7 gt Handover Control Algorithm Program Block Message traffic and counter changes are vital to identify the source of the problem about KPIs 76 5 3 5 HSPA related items to be improved 5 3 5 1 Investigation of large ICSU files Problem Definition Because there is a huge traffic in the operator s live network it is difficult to find the root cause of certain HSDPA or HSPA accessibility problem without proper tool which would easily show the required information Typically the problems that have to be investigated are HSDPA or HSPA accessibility issues which would mean that Handover Control Algorithm Program Block does not
78. nt Interface Program Block interface is also used for trace and online monitoring Distributed Statistics Mediator library implements both Periodical RNW Measurement Interface Program Block and Statistic Report Handler Program Block interfaces 11 This is an interface for monitoring tools Monitoring Tool Mediator activates and deactivates trace data collection to HC master HC hand sends the actual trace data to Monitoring Tool Mediator 4 5 Handover Control Process Family 4 5 1 Handover Control Master Process 16 As explained in the previous chapters the Handover Control HC implements the handover decision algorithm of the RNC The Handover Control has two processes a master process and a hand process The master process is active as long as the RNC is up and running The hand processes are call specific and they are created and removed when needed 55 The Handover Control Master Process is responsible for maintaining an on line copy of the Radio Network RNW database parameters and providing an interface for every handover control hand process to read these parameters Only the Handover Control specific RNW parameters are provided to the HC master The HC master is also responsible for creating and supervising an HC hand providing a statistical interface and managing process warming and switchover The memory consumption of the HC master process is dependable on the network configuration That can be controlled by configura
79. ometimes difficult to get from customer and it is sometimes also difficult to analyze By getting the information directly out from the ICSU data would be good advantage For a better solution provided by this tool detailed information can be collected from ICSU logs and processed or demonstrated in desired way Live network needs amp Internal testing needs Condensed information could be useful in numerical format and also in some graphical format For example e Frequency of requests e Number of requests per trigger cause e Number of ACKs and Number of NACKs with specific failure cause e The success and failure ratio on cell level e How many requests from certain cell and how many NACKs or ACKs from certain cell and BTS The information would be useful to get on cell level and on BTS level Implementation No need to have new functions data types in Handover Control Algorithm Program Block the values will be stored and processed by the tool Proposals ICSU logs have to be collected and then processed in terms of important values to report After doing required calculations condensed values can be reported in table or graphic format 5 3 5 2 HSPA Accessibility Problems Parameter Inconsistency Problem Definition E_DCH operational state is used by BTS to report to HSUPA operational state of the cell In order to use HSUPA in a cell the BTS must have reported HSUPA Operational state to be enabled in that cell Otherwise
80. on Transmission Transmission gap 1 gap 2 gap 2 gt SSN Gi 4 TGL2 Figure 19 Compressed Mode pattern 10 pp 224 During the gaps of the compressed mode the fast power control cannot be applied and part of the interleaving gain is lost 4 pp 256 The RNC algorithms for activating the compressed mode are important to guarantee reliable handovers while maintaining low compressed mode usage 4 pp 257 The RNC determines which frames are compressed and sends the information both to the Node B and to the UE There are three methods to generate the gaps to use CM 10 pp 223 e Reducing the data rate used in the upper layers higher layer scheduling e Reducing the symbol rate used in the physical layer rate matching and or puncturing e Spreading factor splitting halving the spreading factor doubles the available symbol rate Compressed mode also affects the uplink coverage area of the real time services where the bit rate cannot be lowered during the compressed mode Therefore the coverage reason inter system handover procedure has to be initiated early enough at the cell edge to avoid any quality degradation during the compressed mode 4 pp 257 Extra power needed because of compressed mode Normal frame Gap Normal frame Compressed frame Figure 20 Effect of compressed mode on the coverage 4 pp 257 28 3 2 3 Intra System Intra Frequency Hard Handover Hard handove
81. on proposal has been made see 5 3 2 for detailed analysis Required message types were identified to build the topology For future studies new type of visualization objects can be added such as downlink RF channel number downlink scrambling code of the WCEL and Absolute radio frequency number And it is important to update the implementation according to the software baseline data type changes In Missing Neighbour Cell Definitions implementation proposal has been made see 5 3 3 for detailed analysis For this issue detected cell reporting feature has to be turned on Throughout the evolution of Cellular Radio systems cell sizes are decreasing and number of cells is increasing thus number of handover attempts are also increasing Neighbour cell definitions are very important for handover algorithms For future studies there can be an automated self check in the RNC software for neighbour cell definitions which is based on the reports that are received from UE s In Handover Related Troubleshooting KPI calculation comparisons and log file filtering is very important Implementation possibilities were proposed see 5 3 4 for detailed analysis A KPI calculation comparison is a complex process that cannot be used for all handover related problems Only if there is a suspicion about KPI values comparison can be done for the KPI values On the other hand log file analysis is a n every day activity for troubleshooting experiences For fut
82. or one service The abstraction was implemented by abstract data types which have their internal data structures and service interface The service interface consists of many independent service offering operations This implementation method supports object oriented programming suggestive of implementation solution which supports thinking and designing of data structures and combinations of different operations rather than just thinking and designing of the functionality Parameter and return values of functions are the communication tools of the operations This section concentrates on the current usage of abstract data types from the point of view of memory consumption The HC hand functionality in the Drifting RNC DRNC and in the Serving RNC SRNC side differs from each other The DRNC functionality is very limited and contains only the active set update and providing of the neighbour cell lists of the active set cells to the SRNC The DRNC functionality does not contain any sophisticated handover decision algorithms The SRNC HC hand is responsible for all handover decision algorithms Because the DRNC HC hand can take a role of the SRNC HC hand at any time the DRNC HC hand uses the same data structure as the SRNC HC hand The challenges and the troubleshooting experiences that are analyzed in the next chapter are mostly related with HC hand processes and their transactions with different RNC software elements 57 5 Troubleshootin
83. ording to these approaches when the parameter inconsistency is identified the tool can do the following see Figure 33 1 Create alarms warnings The tool can provide a report about inconsistencies including the related ICSU information In addition to different query options there can also be different reporting options to provide needed information in a meaningful way The tool can provide options about how to visualize that information to the screen On the other hand filtering the results may also create process load In addition to ICSU object class object based results there can also be condensed results such as a list of corrupted ICSU s or a list of corrupted parameters For end users e g operators the tool may also create DMX alarms DMX alarms are used the report important situations directly to the operators Implementation of DMX alarms can be analyzed upon request For detailed troubleshooting the tool can also provide a dump file or the printout of the corrupted data to determine the root of the cause or mechanism behind the fault There can also be EMIL compatibility for detailed investigation 66 For data storage using a computer log is probably not feasible due to its limited size and possibility of overwriting other important information in the log Storage memory is a problem Writing all the needed data to a new file can be a suitable solution 2 Force RNW Manager for parameter update to the correspon
84. otalData 5000000 TotalGBR 0 Tota INBR 0 Rem 5000000 WSPI_SumAct 1 RxData 24 CC EnabledQ 3 000041 15 04 12 50 17 738 192 168 255 208 9f FSP 2491 lt 1 5 04 11 50 23 150112 gt 02 DBGTUP _UP Received HsdpaFclnd message for Userld 52911 PrioQld 0 OOI 000042 15 04 12 50 17 738 192 168 255 208 a0 FSP 2491 lt 15 04 11 50 23 150148 gt 02 DBGTUP_UP HsdpaFcInd AirlfThoughput 22715 000043 15 04 12 50 17 738 19 11 50 23 150180 gt 02 DBGTUP 000363 15 04 12 000364 15 04 12 50 17 847 192 168 255 41 ab FSP 240D lt 15 04 11 50 23 251089 gt 1005D DBG LGC P RLH_RM_HSResReconfigCommit cmecki 8480 nbecld 143 000365 15 04 12 50 17 847 192 168 255 41 ac FSP 240D lt 15 04 11 50 23 251 195 gt 1005D INF LGC B RLHSR_RLC_RiReconfigCommit nbeckl 143 000366 15 04 12 50 17 847 192 168 25541 ad FSP 240D lt 15 04 11 50 23 251 396 gt 1005D INF LGC B RLH_CTRL_HSRIReconfigCommitResp nbecld 143 dchAddr 0x22 000367 15 04 12 50 17 847 192 168 25541 ae FSP 240D lt 15 04 11 50 23 251433 gt 1005D DBG LGC P RLH_CTRL_HSRIReconfigCommitResp smccld 8480 nbecld 143 initialRih 022 15 04 12 53 46 248 192 168 255 208 4d FSP 2491 lt 1 5 04 GTUP_UP CQueue32932M0P0 m_TpEstim 12192000 ta Received During eration 0 FC_CRtp 3966 Figure 34 Transition from log file to network topology table Another option is to provide this functionality inside a new troubleshooting tool In both cases required infor
85. r HHO is a category of handover HO procedures in which all the old radio links of a user equipment UE are released before the new radio links are established For real time RT bearers it means a short disconnection of the bearer for non real time NRT bearers HHO is lossless 10 pp 211 Intra frequency HHO is needed when cells participating in the HO are controlled by different RNCs in situations when the inter RNC HO cannot be executed as a soft handover SHO or if SHO is not allowed Intra frequency HHO causes temporary disconnection of the RT RAB but is lossless for NRT bearers Its decisions are made by the RNC based on the intra frequency measurement results the UE is sending periodically after it has reported an intra frequency triggering event and the active set could not be updated and relevant control parameters The reports are usually applied to the SHO procedure so intra frequency HHO is a mobile station evaluated handover MEHO 10 pp 213 By performing an HHO when SHO is not possible excessive interference can be avoided During the HHO procedure all links in the active set are replaced simultaneously by one new link 10 pp 213 3 2 4 Intra System Inter Frequency Handover Inter frequency Handover IFHO is a hard handover HHO between different WCDMA carriers required to ensure a handover HO path from one cell to another cell in situations when different carriers have been allocated to the cells in questio
86. rammes towards 3G systems and the ETSI decision E ASA E TE E E E ES EA 7 Figure 3 3GPP organizational partners 4 pp 67 sssssssssssssssesssssesssssssessreessssssssrerreesss 8 Figure 4 3GPP RAN TSG Working Groups 4 pp 68 eeeeeeseceeceeeeeeeeeeenneeeeeeeees 9 Figure 5 UMTS high level system architecture 4 pp 76 eeesseesseseeeeeeeeneeeeeee 10 Figure 6 UTRAN architecture 4 pp 78 wsiciciecseaivasncesdadeccsadersacesins sachs jabs sdesdndeeceaiages 11 Figure 7 UTRAN architecture extended 4 pp 76 eee eesenceeeeeeeeeeeeeesnneeeeeeees 12 Figure 8 FDMA TDMA Hybrid FOMA TDMA and CDMA 3 pp 26 27 14 Figure 9 Allocation of bandwidth in WCDMA in the time frequency code space Ae DAS oes cheered tented ecaas bee tente E abe ee iekeels a tae oa a 14 Figure 10 WCDMA radio access network architecture 6 pp 132 eeeeeeeeeeeeeees 15 Figure 11 Network Diagram for HSPA traffic user plane 6 pp 28 eee 16 Figure 12 HSPA Standardization and Deployment Schedule 8 pp 7 eeee 17 Figure 13 HSPA Evolution 7 pp 4 ssavssssccceceseecivesancaiveciavstevsancatenesavedveusseseneesaccivses 17 Figure 14 HSPA deployment with f2 new carrier deployed with HSPA and f1 carrier shared between WCDMA and HSPA 7 pp 5 eeeeeeeeeneeeeeeeeeeeeeeeenteeeeeeeees 18 Figure 15 Soft Handover 3 PP 5l co sacneshasleieiviesintn hasten Mecsas dnt ac
87. rate and latency does not play any role GPRS Release 99 typically provides 30 40 kbps with latency of 600 ms EGPRS Release 4 pushes the bit rates 3 4 times higher and also reduces latency below 300 ms The EGPRS data rate and latency allow smooth application performance for several mobile based applications including Wireless Application Protocol WAP browsing and push to talk 8 pp 6 WCDMA enables peak data rates of 384 kbps with latency of 100 200 ms which makes Internet access close to low end digital subscriber line DSL connections and provides good performance for most low delay Internet Protocol IP applications as well HSPA pushes the data rates up to 1 2 Mbps in practice and even beyond 3Mbps in good conditions Since HSPA also reduces network latency to below 100 ms the end user experienced performance is similar to the fixed line DSL connections No or only little effort is required to adapt Internet applications to the mobile environment Essentially HSPA is a broadband access with seamless mobility and extensive coverage Radio capability evolution from GPRS to HSPA is illustrated in Figure 1 9 HSPA was initially designed to support high bit rate non real time services The 19 simulation results show however that HSPA can provide attractive capacity also for low bit rate low latency applications like VoIP 3GPP Releases 6 and 7 further improve the efficiency of HSPA for VoIP and other similar applications 8 pp 6
88. reports from DRNC RNSAP via dedicated Iur process 7 Base station Resource Manager Program Block provides cell load information to HA3 m as well as it indicates need for load service or HSPA Capability based handover to HC hand via this interface This interface exists only if service and load or HSPA capability based handover functionality is enabled 54 8 This interface is for uplink DCH quality reporting In serving RNC the outer loop power control informs HC hand about uplink DCH quality deterioration via this interface 9 Location Based Services Program Block sends request for assisted GPS measurement to Handover Control Algorithm Program Block which then later delivers the results of assisted GPS measurement back to Location Based Services Program Block 10 This interface is for Distributed Statistics Mediator Distributed Statistics Mediator is a Statistical library module linked into Handover Control Algorithm Program Block Distributed Statistics Mediator provides functions related to statistical counter updates Periodical RNW Measurement Interface Program Block uses Distributed Statistics Mediator interface to start and stop periodical measurements and to collect measurement data from a data provider such as Handover Control Algorithm Program Block Data of active measurements is sent to Statistic Report Handler Program Block based on Periodical RNW Measurement Interface Program Block commands Periodical RNW Measureme
89. rk management radio network recovery databases and state management The Interface Control and Signalling Unit ICSU provides the signalling protocols for Ju Jub Iur and Uu interfaces NBAP RNSAP RANAP RRC AAL2 It is also responsible for termination of the SAAL signalling links monitoring and recovery of the signalling links admission control handover control load control radio resource scheduling and management and cell based locationing for LCS Distributed Signal Processing Unit DMCU that provides support for macro diversity handovers and packet data processing as well as other L2 functions related to radio interface 44 4 2 3 mcRNC mcRNC is the new generation of the RNC solution in Nokia Siemens Networks which has a completely new hardware architecture and changes platform and the software side because of the increased capacity and performance requirements As the mcRNC has only one type of processing hardware it allows in theory a large degree of freedom in design of functional software architecture In reality the reuse of existing software as well as logical structure of RNC limits the option space Similar as CRNC mcRNC can also expressed with 4 planes Control Plane User Plane Transport Plane and Management Plane In mcRNC architecture the services of the Control Plane and User Plane are functionally divided based on whether they are provided for a specific UE common entities like BTS and cell
90. s or centralized in the Network Element for architectural reasons The resulting functional units are CSCP Cell Specific functions and services in Control Plane USCP UE Specific functions and services in Control Plane CFCP Centralized Functions and services in Control Plane CSUP Cell Specific functions and services in User Plane USUP UE Specific functions and services in User Plane This includes the dedicated and shared channel services since they are relevant for a UE The Transport plane is divided based on whether it provides services for the internal network also referred to as backplane or external network external interfaces SITP Signalling Transport Plane EITP External Interface functions in Transport Plane Backplane The internal backplane is realized using the Ethernet switch internal side a program block from the application domain resembling a Service Access Point SAP and services provided by IPA Light including the kernel module for transferring DMX messages 45 4 33 RNC SW Architecture 4 3 1 Structural View cRNC The general structure of RNC SW architecture that consists of IPA2800 ATM platform and RNC application parts is depicted in Figure 25 RNC Network Element includes SW on top of three different Operating Systems DMX Chorus and OSE Applications RNC Application Software ee lal Switching Platform 3 Software Platform Figure 25 cRNC SW archit
91. s overall control of the logical resources of its BTS s Both serving and drifting RNCs serve as controlling RNC for the cells they control 4 2 Nokia Siemens Networks RNC Solutions 4 2 1 IPA2800 Platform Nokia Siemens Networks continues the work that its predecessor Nokia Networks did earlier as a developer of network elements A network element is a complex network of inter connected computer units The system consists of various computers with different tasks of their own communicating with each other via message connections As Jyri Ilama mentioned in his master s thesis In early 70 s the research and development process of DX200 started at Nokia Networks and the first customer deliveries took place in the year 1980 in the form of a Fixed Network Switching Centre FNC Later multiple DX200 based products have been developed such as MSC HLR and BSC Anyhow the capacity and performance of the old DX200 started to become obsolete before the turn of millennium and it was discovered that this system won t be able to handle the requirements of telecommunication systems of the third generation This was the need that started the developing of IPA2800 a DX200 based system which is much more efficient and clearer of its architecture than its predecessor was But IPA2800 is not a substitute for DX200 it works in parallel with these old systems hand in hand offering new resources and possibilities that are needed by the third
92. ss is a service point where service requests are handled The master process may handle the request and offer the services or it may create a hand process to do the work 15 4 4 Radio Resource Management of WCDMA RAN Service Block Radio Resource Management of WCDMA RAN Service Block is responsible for air interface resource allocation in RAN It s main task is to optimize the use of the available radio resources such as transmitter power and the usage of spreading codes in order to provide users with the largest possible capacity for given coverage and quality of service requirements 13 pp 46 Radio Resource Management of WCDMA RAN Service Block provides Load Control Admission Control Packet Scheduler Code Management and Handover Control functionalities to the RNC application Radio Resource Management of WCDMA RAN Service Block MS Connection Location Handover Control F Control i Services Algortihm Program RNW User Equipment Manap Radio Resources Program Block PM N Services Base station Transport D Resource Manager Resource P E rogram Block a Management Figure 28 Radio Resource Management of WCDMA RAN Service Block Diagram 13 pp 48 Task division inside service block 49 e Handover Control Algorithm Program Block is responsible for handover control of UEs e Base station Resource Manager Program Block is responsible for load control admission control code management
93. t to location services 4 4 1 The Interface Control and Signalling Unit The Interface Control and Signalling Unit ICSU performs all the signalling transactions towards the other network elements and UE The unit is responsible for the following tasks e Signalling protocols to Ju lub Iur and Iu BC interfaces for o NBAP RNSAP RANAP SABP signalling o ALCAP Q 2630 1 signalling o RRC signalling e Monitoring and recovery of the signalling links e Service Area Broadcast SAB e Radio resource management functions o Admission control AC o Handover control HC o Load control LC o Packet scheduling PS e Location service control functions Through the focus of this thesis handover related transactions take place in ICSU In other words ICSU has a key role in the success of handover functions 4 4 2 Handover Control Algorithm Program Block The functionality of handover control is implemented in Handover Control Algorithm Program Block Handover Control Algorithm Program Block has one master process and several hand processes A Handover Control Algorithm hand is created in serving RNC together with the radio resource control RRC connection establishment for the UE and it exists until the RRC connection is released In drift RNC Handover Control Algorithm hand is created when the first radio link is established for diversity handover and it exists until last radio link of the diversity handover is released The software 52 arch
94. t continues after the product is deployed to the live networks From engineer s point of view a harder phase starts with the deployment Problems from different operators come to the R amp D engineers to be solved At this level most important phase is troubleshooting The approach that is mentioned in the prior chapters Troubleshooting Experiences is commonly used for RNC related challenges Troubleshooting phase is usually a cumbersome process that requires analyzing big number of data Any improvement that is done during this phase would increase the efficiency of software lifecycle In NSN the team that is cooperated for this thesis is mostly interested about the Handover Algorithm related challenges that occur in any R amp D processes which includes the existing software versions and the upcoming versions As a team it was decided to prepare a thesis work to enhance the troubleshooting experiences During the topic and scope decision phase there were many meetings done to identify the needs of the team from different perspectives and to keep the scope under timing and workload targets As a result several use cases were defined and the consultancy for the thesis has mostly continued individually with the responsible senior engineers In the following chapters different use cases will be presented with their problem statements existing solutions live network needs internal integration and verification needs implementation
95. t parameter values in different ICSU s HC master memory There can be several problematic scenarios e Radio Network Manager sends wrong data e Radio Network Manager sends correct data to a wrong ICSU e Radio Network Manager sends correct data to ICSU s but not to all of them 62 e Radio Network Manager sends correct data but HC master is unable to receive or process the data correctly e Radio Network Manager does not notify the parameter changes to ICSU s Existing solution for the problem Currently parameter consistency check can be done by requesting Handover Control Algorithm parameter printout from different ICSU s by 1 Starting message monitoring in ICSU 2 Sending parameter query to HC master process 3 Collecting monitoring logs size of log files are around 10 MB per ICSU After parameters have been collected from each ICSU they are manually checked by comparing with the operator s own RNW plan No special tool is available for that purpose Message monitoring is done manually by using EMIL tool Live network needs The tool has to create alarms warnings for parameter inconsistencies and clearly show the relevant database parameter inconsistencies in terms of related ICSU and parameters The only way to catch the data corruption that occurs at RNC RNW Database Library interface is to have Handover Control Algorithm message monitoring running already when RNC or ICSU s are starting up or RNW database is b
96. t the radio connection is uninterrupted while the user equipment moves in the network 10 pp 211 Power Control Since the capacity of any CDMA system is limited by interference it is crucial that all base stations and terminals in the radio access network use the least possible transmission power The purpose of power control is to use as little transmit power as possible in both uplink and downlink while maintaining the quality of the connection 4 pp 55 From this thesis point of view the Handover Control algorithms will be examined in detail in the following sections 3 2 Handover Control Mobile phones can maintain their connections in cellular networks when they move from one cell area to another The procedure which switches a connection from one base station to another is called a handover HO or a handoff It is possible that an HO does not involve a change of the base station but only a change of radio resources 3 pp 37 38 The primary function of the handover control algorithm is to monitor the quality of a dedicated radio connection and to perform a soft or a hard handover if the quality is insufficient Briefly maintaining seamless communication for mobile users is the main duty of handover control algorithms 22 There are various reasons that could cause a handover for an UE The reasons can be 11 pp 15 e Uplink quality e g bit error rate BER e Uplink signal measurements e g received s
97. ted printout of the RNW network topology One of the implementation possibilities is creating an EMIL script that could draw this type of table or chart The main concern about EMIL implementation is how easy or how hard will it be to create a global data structure where the data from filtered query messages can be stored Processing the information and producing the printout should not be an issue 69 000084 15 04 12 50 17 723 192 168 255 208 98 FSP 2491 lt 15 04 11 50 23 1404 825 2 DEGITUP_ JP HsdgeF Ind Buf ere 000085 15 04 12 50 17 723 192 168 255 208 99 FSP 2491 lt 15 04 11 50 23 140736 gt 02 DBG TUP_UP CQueue32910MOPO m_TpEstim 2070500 BuO temp 727 m_DataReceivedDuringheration 0 FC_CRip 727 FC_lastCRip 770 SEN 368 000036 15 04 12 50 17 723 192 168 255 208 9a FSP 2491 lt 15 04 11 50 23 140779 gt 02 DBGTUP_UP CQueue32910M0P0 m_DataPrev_period 0 m_DataST 6560 000037 15 04 12 50 17 723 192 9b FSP 2491 lt 15 04 11 50 23 140830 gt 02 DBGITUP 117 RxData 0 AllocPrev 66400 bps 000088 15 04 12 50 17 723 192 168 255 208 9e FSP 2491 lt 15 04 11 50 23 140871 gt 02 DBGTUP_UP Received HsdpaFclnd message for Userld 32911 PrioQld 7 000039 15 04 12 50 17 723 192 168 255 208 9d FSP 2491 lt 15 04 11 50 23 140909 gt 02 DBG TUP_UP Received HsdpaFclnd message for Userld 32010 PrioQld 7 000040 15 04 12 50 17 723 192 168 255 208 9e FSP 2491 lt 15 04 11 50 23 146825 gt 02 DBGTUP_UP CCRncGroup0 T
98. ter data for traffic and cell resource measurements Counter data collection is performed through Distributed Statistics Mediator library which is linked to each provider application This interface is also used for online monitoring User Equipment UE connection management controls the UE mobility and connections between UE RNC and core network CN and performs related signalling at L3 level also handover HO signalling UE connection management uses UE resource management services for RAB related operations NBAP protocol Node B Application Part NBAP protocol sends periodically cell specific load information and radio link specific load information from BTS Dedicated BTS measurements are controlled and reported through NBAP Layer 2 services offer radio lank control RLC and medium access control MAC protocols MAC protocol is informed whether common channels can be used for data transfer in downlink direction depends on load conditions in radio interface Also it is used for reserving Data and Macro Diversity Processor Group DMPG resources for HSDPA channels Transport resource management offers a service through which HS DSCH transport resource allocation can be performed 51 Location services LCS request Handover Control Algorithm Program Block to perform assisted GPS measurement Handover Control Algorithm Program Block delivers LCS related measurement results assisted GPS measurement Rx Tx measuremen
99. the specifications was originally considered as Release 2000 but in the meantime the release naming was adjusted so that the next release in March 2001 was called Release 4 and the numbering continued 3GPP release history can be seen in Table 2 10 Version Date Release Info Release 99 2000 Q1 Specification of first UMTS 3G networks Release 4 2001 Q2 All IP Core Network features added Release 5 2002 QI IP Multimedia Subsystem IMS and High Speed Downlink Packet Access HSDPA introduced Release 6 2004 Q4 Integration with Wireless LAN added High Speed Uplink Packet Access HSUPA and Multimedia Broadcast Multicast Service MBMS introduced enhancements to IMS added Release 7 2007 Q4 Improvements to QoS and support for real time applications added Enhanced Data Rates for GSM Evolution EDGE Evolution High Speed Packet Access Evolution HSPA and Near Field Communications NFC introduced Release 8 2008 Q4 Specification of first LTE networks All IP Network approach introduced Orthogonal Frequency Division multiple access OFDM Single Carrier Frequency Division Multiple Access SC FDMA or FDE and Multiple Input and Multiple Output MIMO added Dual Cell HSDPA introduced Release 9 Release 10 2009 Q4 2011 QI All IP Network enhancements added WIMAX and LTE UMTS interoperability added Dual Cell HSDPA with MIMO introduced Dual Cell
100. the problem investigation Data collection can take place in interface level or directly from a database Symptom Collection tools often provide filtering options by using different query scripts to the user for better experience Subscriber tracing is another important option that is provided by symptom collection tools In addition to IMSI based filtering complementary data from the different parts of the network for particular subscriber has a big value for troubleshooting In Symptom Analysis knowledge for network architecture and signalling protocols become vital for analysis The tools have to provide network analyzing and subscriber tracing features for advanced troubleshooting At this level providing signalling flow charts can easily reveal the causes of the problem Vendors usually have different tools for data collection and the compatibility of those tools is vital for troubleshooting experiences In Fault Repair phase according to the internal fault repair policies engineers can either report their results by proposing a software change or configuration change to the software development team They can also do the fix by themselves In R amp D team a tool called EMIL is used for the first two phases Details about EMIL are introduced in the next chapter 59 5 2 EMIL Eek Time lt ARC measurementControl 16 41 20 368 ARC measurementReport gt 16 41 20 67 16 41 20 67 16 41 20 67 RRC measurementReport gt
101. the relevant database parameter inconsistencies in terms of ICSU and parameters Internal testing expectations from the desired tool The tool has to create alarms or warnings for parameter inconsistency The tool also has to provide debugging features for the problem in terms of queries messages and responsible functional units Implementation Additional functions or features to get the information from Radio Network Initiator and JICSU s might be needed After getting the HSDPAOperationalState and HSUPA OperationalState parameters the tool can compare them 79 Proposals The tool has to get the correct values of the parameters from Radio Network Initiator and then compare with the ones in Handover Control Algorithm and then it can e Create alarms or warnings e Force Radio Network Initiator for parameter update e Force Handover Control Algorithm to ask for new set of parameters e Debug messages can be used between Base Station Resource Manager Program Block Handover Control Algorithm Program Block 5 3 5 3 Calculation of certain Parameters related with HSPA Problem Definition UL S Rerror and periodical CPICH Ec No values are used in handover control algorithm decisions While investigating issues problems in handover control algorithm related to HS D PA functionality those values has to be analyzed in order to see if the algorithm works correctly and utilizes correctly those inputs that are coming from UE and BTS Curren
102. tion Handover Handover is the process to maintain seamless communication while users are mobile between different cells sectors inside the network EMIL An internal tool that is designed to investigate call traces and other logs for verification purposes Troubleshooting Troubleshooting is the chain of processes which aims to identify a particular challenge inside the software and try to propose solutions or workarounds 1 Introduction Wireless Communications has become step by step indispensable in people s life as it is utilized more and more For service providers it also becomes vital to use their wireless resources efficiently Radio Resource Management RRM is the solution to maintain seamless mobility and resource efficiency In WCDMA Radio Access Network RAN architecture Radio Network Controller RNC is responsible from RRM duties Radio Resource management functions are split into 6 different groups of algorithms e Admission Control e Load Control e Packet Scheduler e Resource Manager e Power Control e Handover Control The software development for Nokia DX type of digital switches was started in early 70 s and with the ease of its modular design DX architecture followed the technology evolution and was used for GSM mobile technology as well As an ancestor software for Radio Network Controller continued from the existing DX200 software and it became more complex with the specifications of 3GPP for WCDMA
103. tion parameters and hence the memory usage of the HC master is not an issue in different hardware environments In addition to normal hand creation and supervision functions HC master maintains a local copy of RNW parameter database in its own memory and provides an interface for hand processes to read these parameters Only HC specific RNW parameters are stored in HC masters memory Process warming and switchover control functions are implemented in the HC master as well 4 5 2 Handover Control Hand Process 16 An HC hand is created in the SRNC serving RNC when the RRC connection on the Cell_DCH state is set up and it exists until the UE leaves the Cell_DCH state The UE is in the Cell_DCH state if at least one dedicated transport channel is set up In the DRNC drifting RNC an HC hand is created when the first soft handover SHO branch over Jur is set up and it exists until the last soft handover SHO branch over Jur is removed The HC hand provides all UE dedicated handover functionalities in the Cell_DCH state This is why most of the implementation is done in the HC hand code area Because there can be thousands of HC hand processes in a computer unit at the same time every new bit of memory needed by the HC hand is multiplied by the number of the active HC hand processes 56 4 5 3 Module Structure of HC Hand Process 16 The HC hand was abstracted according to developed services The intention was to have one module f
104. tly the R amp D team needs to calculate averaged UL STRerror and periodical CPICH Ec No measurement results of a certain cell based on ICSU log by hand which is not a very efficient way Existing Solution for the problem Periodical CPICH Ec No reports come from UE and UL SIRerror reports come from BTS Those values are captured in logs by automated macros and then calculated by hand Live network needs amp Internal testing needs Averaged UL S Rerror and periodical CPICH Ec No measurement results of a certain cell which is defined by the user are needed Implementation No need to have new functions or data types in Handover Control Algorithm Program Block the values will be stored and processed by the tool Another option is using EMIL scripts for calculation Proposals The tool has to get the UL SIRerror and CPICH Ec No values from the ICSU log Then it will calculate the averaged UL SIRerror and periodical CPICH Ec No measurement results for certain cell which is defined by the user 80 6 Conclusion During the topic decision phase of this thesis the main problem statement was how to enhance the troubleshooting experiences of the R amp D engineers At the beginning I was guided to increase my knowledge more on Radio Resource Management and then particularly about Handover Algorithms Later on team meetings were organized to reveal the existing troubleshooting experiences and difficulties At that point I started to be
105. uable comments on this thesis Most of all I would like to thank to my family my mother my father and my beloved Elis for all their support and encouragement that they have given me throughout my studies In Espoo 30 09 2011 vi Table of Contents TEAC n ane a A E E E E A N R v Acknowledgements naimena oe e hele edd ae a EET E E EEEE v Table GR Contents rA e E A N vi List of ACTONY MS essiri vossrssasetancescdsansdaseasedeaceeasesivoannseacddeessaeaandhaocadesauodiaaa KIIRE oat vii Pist Of PU SUT OSs 255255 inene ae aea e a e a E noes xiii List OF Table Seice eea aines EEEa ES AES a EOE E raa a Eea xiv EALE E 01 EEE E unk oda E T E XV 1 Introductions sensn aa E E E S Ra 1 1 1 Problem Statement and The Objectives eeeeecsccccceceeeseeesneeceeeeeeeeeeeseeaeees 1 1 2 gt SUUCHIES of the THESIS s s syacseingreassantensceshareyassoseuaesenzeieasoutannatonsaangeavaest heats 2 2 WCDMA and HSPA Basics i ciaccscteavesiossassinsdeaccessasivaansanasactveadesiusdenveatcevovednsaass 3 Da lh Evolution to SCH eea ache apecad a Cashed cdtacagd eh Ea a e EE aE E A Eai 3 2 2 UMTS Radio Access Network Architecture cccccccceeeeesetneeeeeeeeeeeeeenanees 10 23 WCDMA re he Sit a agra eskecdy esse cs sles aves ashieegite oe ou ara e na ae hes 14 DAR E E ca PCR R ORE AUTOR CROCUS Er AE OME MR CUE RCE So SATIRE EMR een Re aR CPR 16 37 Mobility m UMTS eessen ta cence einer ee aes 20 3 1 Introduction to Radio Resource Management
106. umen bats 23 Figure 16 Softer Handover 3 pp 270 ssssesssessssssseessesssssssssssreesssssssereseessssssssesereessse 23 Figure 17 Inter system handovers between GSM and WCDMA 4 pp 255 24 Figure 18 Inter system handover procedure 4 pp 256 scccccceeeeseeetttteeeeeeees 25 Figure 19 Compressed Mode pattern 9 pp 224 0 eee eeeesenneeeeeeeeeeeeeennneeeeeeees 27 Figure 20 Effect of compressed mode on the coverage 4 pp 257 sesssseeeeeeeees 27 Figure 21 Intra frequency Measurements 9 pp 219 eessssessessrersessrerrssrersssererssseee 34 Figure 22 Time to trigger Mechanism for Event 1A 9 pp 219 36 Figure 23 UTRAN Network Elements sseeseeeeeseesseesssrressssreesssrrerrserreerssreesssereesssere 40 Figure 24 Functional architecture of the CRNC 12 pp 31 ee eeeeeeeseteeeeeeeees 42 Figure 25 cRNC SW architecture 12 pp 38 ass eee a a aS 45 Figure 26 mcRNC SW architecture 12 pp 39 0 eeeeeeeeesnnneeeeeeeeeeeeeennneeeeeeeees 45 Figure 27 Service model architecture 12 pp 40 ee eeeesenceeeeceeeeeseeennneeeeeeeees 47 Figure 28 Radio Resource Management of WCDMA RAN Service Block Diagram fr MPa AES Sttas tess E sagutasainedsptiahsSigeluanea ss bbuseieanest 49 XIV Figure 29 Handover Algorithms Program Block Diagram e ee eeeeeeeeeeeeneeeeeee 52 Figs te 30 EMIL Screenshot oniinn eaae ea iae e a a Aaa 59 Figure 31 Handover Control
107. ure studies there can be new parameters required to be in the filtered report In HSPA related issues similar problems were analyzed from HSPA perspective and implementation proposals have been made see 5 3 5 for detailed analysis Calculation of certain parameters related with HSPA is an everyday need for troubleshooting experiences Required parameters can be updated upon request in the future The enhancement for HSPA Accessibility problems is important because it is hard to investigate the problem from log files In the future parameter set can be updated if there is a new software baseline Similar to previous analyses using large log files is always time consuming thus it is also important to provide this feature 82 To sum up the scope of this thesis was to analyze the existing troubleshooting experiences in NSN WCDMA Control Plane Handover Algorithms team and study the enhancements opportunities to increase the efficiency of R amp D engineers Study cases were chosen after long discussions to increase the R amp D engineer s benefit from this work The benefit of this study will show itself in the long run In the future it would be good to continue this type of efficiency related studies for different troubleshooting cases and for different software platforms 7 10 11 12 13 83 References Mishra A R Fundamentals of Cellular Network Planning and Optimisation 2G 2 5G 3G Evolution To 4
108. vels system blocks service blocks and program blocks 13 pp 40 e System block SYB is hierarchically the highest block and it offers a defined number of related services and implements a defined number of functions e Service block SEB is a part of the implementation of a system block offering certain system block services to others and a number of services used within the system block e Program blocks PRB is the actual implementation of the service blocks Program blocks implement the services of service blocks System Block SYB Service Block A SEB Service Block B SEB Program Block I Program Block J Figure 27 Service model architecture 13 pp 40 48 In the block model illustrated by Figure 27 the services can be hidden so that program blocks belonging to different service blocks do not see each other s service definitions 13 pp 40 4 3 4 Process Family A software block is usually implemented as a process family A process family is a group of independent dynamically allocated state machines One of the state machines is on the controlling position towards others The controlling state machine exists always after the activation of the program 15 A process family consists of a master process and various number of hand processes A process family can also be implemented without the hand processes The master functions as the controlling state machine In a process family the master proce
109. w it is just another SHO The difference is only meaningful to the network as a softer HO is an internal procedure for a Node B which saves the transmission capacity between Node Bs and the RNC 3 pp 39 In the uplink the signal from the mobile station MS is received at different sectors which are combined in softer handover by using Maximal Ratio Combining MRC and in soft handover by using selection combining 10 pp 179 In softer handover with MRC of the signals from different sectors the gain is slightly bigger than in soft handover with selection combining 10 pp 88 UE in softer handover Figure 16 Softer Handover 3 pp 270 24 The main objectives of soft softer HO are the following 10 pp 212 e Optimum fast closed loop Power Control PC as the UE is always linked with the strongest cells e Seamless HO without any disconnection of the Radio Access Bearer RAB e To enable a sufficient reception level for maintaining communications by combining the received signals macro diversity at symbol level from multiple cells in cases when the UE moves to cell boundary areas and cannot obtain a sufficient reception level from a single cell e Furthermore the macro diversity gain achieved by combining the received signal in the Node B softer HO or in the RNC SHO improves the uplink signal quality and thus decreases the required transmission power of the UE 3 2 2 Inter System Handover At the start of WCDMA
110. wards 3G systems and the ETSI decision 4 pp 65 The main objective of the project was to study on a proposal for Universal Mobile Telecommunications System radio access system FRAMES project was supported by several European Universities Nokia Siemens Ericsson France T l com and CSEM Pro Telecom After some discussions two modes were proposed to the European Telecommunications Standards Institute ETSI as candidates for UMTS air interface 4 pp 62 e FMAI Wideband TDMA e FMA2 Wideband COMA In 1997 after the proposal submissions ETSI formed 5 working groups 4 pp 62 e Wideband CDMA WCDMA e Wideband TDMA WTDMA e TDMA CDMA e Orthogonal Frequency Division Multiple Access OFDMA e Opportunity Driven Multiple Access ODMA After getting the full solution proposals from work groups and evaluating the results WCDMA was chosen as the standard for the UMTS Terrestrial Radio Access UTRA air interface on the paired frequency bands and WTDMA CDMA was chosen for the unpaired frequency bands In 1999 technical work for the UTRA transferred to 3 Generation Partnership Project 3GPP 4 pp 65 Standardization studies were taking place in different countries under different committees 4 pp 67 Japan The Association for Radio Industries and Businesses ARIB and the Telecommunication Technology Committee TTC Korea The Telecommunications Technology Association TTA U S A Technical Subcommittee of Standar
111. when ordered by the RNC They use separate measurement reporting criteria transmitted to the UE When they are initiated the UE periodically reports the results to the RNC The 32 measurements are controlled by two parameters reporting duration and the reporting interval 10 pp 216 3 3 2 3 User Equipment Internal Measurements UE internal measurement reporting criteria are controlled partly on a cell by cell basis and partly by parameters common to all cells in the whole RNC The measurement information for UE internal measurements is not included in the system information on the BCCH but transmitted to the UE on a Dedicated CCH DCCH When the measurement reporting criteria are fulfilled the UE reports the results of its measurements to the RNC 10 pp 216 3 3 3 Reporting of Measurement Results When the UE reports the measurement results from the intra or inter frequency measurements of the neighbouring cells back to the UTRAN the following IEs are included to identify the neighbours 10 pp 217 e P CPICH information downlink scrambling code identifies active and monitored cells when the UE reports intra frequency or UE internal measurement results to the RNC e P CPICH information and UTRA RF Radio Frequency channel number identifies neighbouring cells when the UE reports IF measurement results to the RNC e BCCH frequency identifies neighbouring GSM cells when the UE reports IS GSM measurement results to the RNC

WCDMA Mobility Troubleshooting Studies and Enhancements

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