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Wireless Sensor Network Simulator

1. D IMPLEMENTATION OF NS 2 28 BASED WSN SIMULATOR 115 ss 18 struct hdr env main 19 u intl6 t pck length 20 u intl6 t reserved AE inline int sizeQ 1 245 int sz pck length 225 assert sz gt 0 24 return Sz 295 j 27 struct payload 28 nsaddr t msg oAddr 29 u intl6 t msg size 30 u intl6 t msg seqno ol intl6 t environment 32 inline int size 4 221 int sz msg size assert sz gt 0 DOG return 57 36 j Dd 2 Lines 1 to 5 define the different types of the environment packets Lines 6 to 37 declare the general header with functions for all environment packet structures Lines 28 to 31 are the raw attributes of new packets msg Addr describes originating address of broadcast msg seqno describes sequence number of this packet msg size describes the size of the payload environment indicates which types of environment packets have been transmitted as they are defined in lines 1 to 5 The environment agent and the environment packet emanating routing protocols are implemented in the main env cc file TCL Hook Tcl hook is used to bind the new environment packet and the new environment agent to Tcl and let env packet and env agent be instantiated from Tcl static class ENVHeaderClass public PacketHeaderClass 1 public ENVHeaderClass PacketHeaderClass PacketHeader ENV 0 sizeof env bind offset amp hdr env offset
2. hdr PT ENV to enum packet t type PT ENV ENV to p 110 mac cc and wireless phy cc h In the wireless sensor network the sensor node contain at least two interface types Sensor and environment interfaces So the modification mac cc file can avoid the interface counting problem NS 2 contains the energy model for wireless nodes which can describe the power consumption of the wireless node in different states The model includes attributes for specifying the power requirements of transmitting packets receiving packets and the idle standing The sensing environment may consume another rate of power so we must add these power consumption types in wireless phy cc h fles To modity these two files the following codes are added For mac cc Add else if stremp argvll adjust index 0 MacIndex return TCL These codes are added to prevent the MacIndex from the counting mistake which increases double after adding multiple interfaces to a sensor node For wireless phy h Add double Ps consume power consumption for sensing environment in sensor node W fprintf stderr wireless phy h downtarget downtarget 20 IMPLEMENTATION OF NS 2 28 BASED WSN SIMULATOR tcl lib ns lib tcl This Tcl script file defines the node configurations which are specified in the NS 2 Tcl simulation script In the extension we add t
3. else set rcvT cmu trace MAC self j rcvT target mac up target mac up target rcvT if namfp rcvT namattach namfp j H Trace Dropped Packets H If imepflag 7 1 set drpT self mobility trace Drop 5I WIRELESS SENSOR NETWORK SIMULATOR else set drpT cmu trace Drop MAC self j mac drop target drpT if namfp drpT namattach namfp j else mac log target ns set nullAgent mac drop target ns set nullAgent H set sensing energy for sensor nodes Node MobileNode instproc setPs val j self instvar netif_ if info exists netif 1 1 netif 1 setSensePower val j B4 cmu trace h cc void CMUTrace format env Packet p int offset struct payload msg payload struct hdr env main mh HDR ENV p struct hdr cmn ch HDR CMN p struct hdr ip ih HDR IP p struct hdr env hello asymlink symlink mprlink hdr hello struct hdr env tc hdr tc int local offset sizeof struct hdr env main msg payload ENV PAYLOAD p local offset switch msg payload gt environment case TEST ENV sprintf pt buffer offset 96d d d TEST ENV msg payload gt msg oAddr msg payload gt msg_ seqno msg payload gt msg size msg payload gt phenomenon break case CO sprintf pt gt bufferQ offset d d 9 amp d CO msg payload gt msg oAddr msg payload msg seqno
4. Antenna Mobilenode uses an omni directional antenna which has unity gain The implementation is in ns antenna cc h Energy Model The energy model of a node has an initial value as initialEnergy_ It also has a given energy usage for every packet it transmits and receives as txPower and rxPower The initial energy will be decreased by energy usage for every transmitted and received packet When the energy level at the node decreases to zero the node cannot receive or transmit the packet The energy model is implemented in ns energymodel cc h The new energy model is extended in 24 This model is turned into the sleep mode to save energy 42 APPENDIX A BASIC WIRELESS NETWORK MODEL IN NS 2 A4 Different Types of Routing Agents in Mobile Networking There are currently four ad hoc routing protocols DSDV DSR AODV and TORA implemented for mobile networks in NS The implementations which are mainly in can be found in ns tcl mobility dsdv tcl dsr tcl tora tcl ns tcl lib ns lib tcl and ns dsr tora and aodv 5 Trace support There are three types of trace object CMUTrace Drop CMUTrace Recv and CMUTrace Send which are used for tracing dropped received and sent packets by agents routers MAC layers or interface queues in NS The implementation methods and procedures are in ns trace cc h and ns tcl lib ns cmutrace tcl A6 Wireless Trace Formats The trace file is an important output of the simulat
5. antType val ant propType val prop phyType val netif channel chan 1 topolnstance topo 4 agentTrace OFF routerTrace OFF macTrace ON movementTrace OFF for set i 0 i lt 10 incr i 3 tset environment node set node i ns node tfrom node 0 to node 9 node i random motion 0 total 10 nodes god new node node i node i namattach namtrace ns initial node pos node i 25 node i set ragent pulserate 2 0 transmit pulse every 2 sec 56 APPENDIX C EXAMPLE TCL CODES FOR TESTING ROUTING PROTOCOLS configure sensor nodes set val rp AODV amp AODV routing protocol ns node config adhocRouting val rp channel chan 2 SENSORchannel chan 1 for set i 10 i lt 59 incr i set sensor node set node i ns node tfrom node 10 to node 58 node i random motion 1 ttotal 49 nodes zod_ new node node 1 node i namattach namtrace j configure user node set val rp AODV AODV routing protocol ns node config adhocRouting val rp channel chan 2 SENSORchannel off for set i 59 1 lt 60 j incr i 1 node 59 gt user node set node i ns node node i random motion 1 god new node node 1 node i namattach namtrace j H Provide initial X Y for now Z 0 co ordinates for mobilenodes Himport the randommovement file which create and set 10 environment nodes to have r
6. 52 APPENDIX B IMPLEMENTATION CODES FOR WSN CLASSES msg payload gt msg size msg payload gt environment break case HEAVY GEO sprintf pt bufferQ offset d d 96d 96d HEAVY msg payload gt msg oAddr msg payload msg seqno msg payload gt msg size msg payload gt environment break case LIGHT GEO sprintf pt buffer Q offset d d d LIGHT GEO msg payload gt msg oAddr msg payload gt msg_ seqno msg payload gt msg size msg payload gt environment break case SOUND sprintf pt buffer Q offset d d d SOUND msg payload gt msg oAddr msg payload msg msg payload gt msg size msg payload gt environment break default Hifdef WIN32 fprintf stderr CMUTrace format aodv invalidENV packet typeW Helse fprintf stderr s invalid Environment packet type FUNCTION Hendif abort j j 53 WIRELESS SENSOR NETWORK SIMULATOR 54 APPENDIX C EXAMPLE TCL CODES FOR TESTING ROUTING PROTOCOLS Appendix C Example Tcl Codes for Testing Routing Protocols The example Tcl codes for testing AODV routing protocol with 49 sensor nodes in Chapter 3 4 are shown below M G I Q Define options set val chan Channel WirelessChannel channel type set val pr
7. 800 refers to ETHERTYPE IP The next four numbers the second bracket concern the IP source and destination addresses and the TTL Time to Live of the packet The third bracket concerns the tcp information its sequence number and the acknowledgement number A6 2 Revised format for wireless traces The revised format is improved to merge a wireless trace This new trace support is now only available for wireless simulations and will be extended to the rest of NS 2 in the future The following command is used to create this new format ns use newtrace An example of this new trace format is shown below S 0 267662078 Hs 0 Hd 1 Ni 0 Nx 5 00 Ny 2 00 Nz 0 00 Ne 1 000000 N1 Nw Ma 0 Md 0 Ms 0 Mt Is 0 255 Id 1 255 It message 32 ii 0 Iv 32 amp 100 004776054 Hs 0 Hd 1 Ni 1 Nx 25 05 Ny 20 05 Nz 0 00 Ne 1 000000 N1 AGT Nw Ma a2 Md 1 Ms 0 Mt 800 Is 0 0 Id 1 0 It tcp 1020 If 2 I1 21 Iv 32 Pn tcp Ps 0 Pa 0 Pf Po 0 The features of the new trace format are described below Event type The first field describes the event type taking place at the node which can be one of the four types s send r receive d drop and f forward General tag The second field starting with may stand for time or global setting Node property tags This field describes the node properties like node id trace level such as router or MAC The tags that
8. Technical report 0602 January 2006 Wireless Sensor Network Simulator Master s Thesis in Electrical Engineering Thammakit Sriporamanont and Gu Liming oY Gan 2 e ochool of Information Science Computer and Electrical Engineering Halmstad University ER Wireless Sensor Network Simulator Master s thesis 1n Electrical Engineering School of Information Science Computer and Electrical Engineering Halmstad University Box 823 S 301 18 Halmstad Sweden January 2006 Preface This Master s thesis 1s the final step of the Master of Science Degree in Electrical Engineering at Halmstad University Sweden We would like to express our gratitude to our supervisor Prof Tony Larsson for his support and helpful suggestions through out the work on this thesis We would also like to thank Latef Berzenji for his valuable help on the language of this thesis Finally many thanks go to our parents and our friends for their encouragement Thammakit Sriporamanont and Gu Liming Halmstad University January 2006 11 Abstract In the recent past wireless sensor networks have been introduced to use in many applications To design the networks the factors needed to be considered are the coverage area mobility power consumption communication capabilities etc The challenging goal of our project is to create a simulator to support the wireless sensor network simulation The network simulator NS 2 which su
9. 59 j incr i ns at 1 0 appO i start sensor i j Tell nodes when the simulation ends for set 0 i lt 59 iner i 4 ns at 20 0 node i reset ns_ at 20 1 stop ns at 20 1 puts NS EXITING ns halt 58 APPENDIX C EXAMPLE TCL CODES FOR TESTING ROUTING PROTOCOLS proc stop global ns tracefd namtrace ns flush trace close tracefd close namtrace j Begin command line parsing puts Starting Simulation ns run For Testing DSDV routing protocol the above codes are changed only in the parameter of val rp from AODV to DSDV 59
10. 5size char pkt accessdata 3 Packet free pkt As described above the basic idea to generate and transmit the user data in the based NS 2 sensor network simulators 1s shown below 32 EXTENSION OF SIMULATOR FOR SPECIFIC SENSOR NETWORK APPLICATIONS Temperature Sensor Sensor Application Application Simple function Vibration Sensor 1 22 Date Sensor Channels L Wireless Channels 2 UserAgent Mem e y 5 Environment Nodes Sensor Nodes User Node Figure 4 4 The passing data process from the environment nodes to the user node Figure 4 4 shows how the sensor data pass the whole sensor network and finally receive and deal with the user node The environment node generates different kinds of sensor data to send them to the attached sensor channel and when the sensor nodes detect the environment nodes the sensor node agents hand the received sensor data to the sensor application which is attached to the sensor nodes After the sensor application does some basic functions with the sensor data the sensor data will be sent to the user node via the attached wireless channel Finally the sensor data will be reported and analyzed by the user application The methods how to implement this are shown below Step 1 Generate sensor data in the environment module In the environment module we
11. Pe src of srcrouting dst of the source routing Pw error report flag Pm number of errors Pc report to whom Pb link error from link a to link b P cbr The details of the CBR application are Pi sequence number Pf how many times this pkt was forwarded Po optimal number of forwards P tcp The details of TCP flow are Ps seq number Pa ack number Pf how many times this pkt was forwarded optimal number of forwards This field is under development which new tags will be added in the future See 8 10 and 11 for more information 45 WIRELESS SENSOR NETWORK SIMULATOR 46 APPENDIX B IMPLEMENTATION CODES FOR WSN CLASSES Appendix B Implementation Codes for Wireless Sensor Network Classes B1 Environment Module Command ENV command int argc const char const argv if arge 2 Tcl amp tel Tcel instanceO if strncaseemp argv 1 id 2 0 1 tcl resultf d index return TCL OK j if strncasecmp argv 1 start 2 0 htimer handle Event 0 return TCL OK j j else if argc 3 1 if stremp argv 1 pulserate 0 Hello Interval atof argv 2 return TCL OK j else if stremp argv 1 env 0 Envenon types are defined as ints in env packet h if stremp TEST argv 2 ENV Env TEST ENV j else if stremp argv 2 ENV Env CO j else if strcmp HEAVY GEO argv 2
12. j class rtProtoENV hdr static class ENVclass public TclClass publie CON MD OP 59 15 WIRELESS SENSOR NETWORK SIMULATOR 9 ENVclass TclClass Agent ENV 10 TclObject create int argc const char const argv 11 assert argc 5 12 return new ENV nsaddr t atoi argv 4 134 j 14 class rtProtoENV Command It consists of the implementation of the command O method that the environment agent inherits from the agent It seems little more complicated The codes are shown in Appendix ENV command int argc const char const argv This is the normal format of the command functions argv 0 contains the name of the method being invoked argv 1 is the requested operation and argv 2 argc 1 is the rest of the arguments which were passed Within this function we code some mandatory operations as well as any other operations which we want to make accessible from Tcl The following codes show the example when we configure the pulse rate in the simulation script and how the command function fetches it 1 else if argc 3 2 if strcmp argv 1 pulserate 0 3 Hello Interval atof argv 2 4 return TCL OK 5 j Emanate The ENV emanate function which is implemented for the environment packet broadcast in the attached environment channel builds and sends off a hello message The codes are shown in Appendix B2 In the environment module there are
13. 10 random movement environment nodes 111 11m 1000m Q Environment node x Sensor node LL User node Movement direction 111 11m gt 1000m Y Figure 3 8 The simulation model of the 100 sensor nodes in 1000m x 1000m with 10 random movement environment nodes WIRELESS SENSOR NETWORK SIMULATOR 3 4 2 Environment node model Once the environment node which is used to detect the environment target detects the target it generates a data packet and sends it to the sensor nodes The environment node model consists of Link layer MAC layer with the 802 11 type Interface queue with DropTail PriQueue Interface queue length with maximum 50 packets in the interface queue Antenna with Omni directed Antenna Propagation model with TwoRayGround Network interface with WirelessPhy Channel with SENSOR channel Routing protocol with Env routing protocol 3 4 3 Sensor node model The sensor node receives the detected data from the environment nodes and reports them to the user node The sensor model consists of Link layer MAC layer with the 802 11 type Interface queue with the DropTail PriQueue Interface queue length with maximum 50 packets in the interface queue Antenna with the Omni directed Antenna Propagation model with the TwoRayGround Network interface with the WirelessPhy Channel with the SENSOR and the WIRELESS channe
14. 2 2 10000000000000 nnne reete reu 9 32 SIMULATION MODEL OF WIRELESS SENSOR NETWORKS eere 10 33 IMPLEMENTATION SENSOR NETWORK IN 5 2 28 020 02 00 000000000000 12 34 EXAMPLE OF USING THE SIMULATOR TO TEST ROUTING PROTOCOLS eere 22 4 EXTENSION OF SIMULATOR FOR SPECIFIC SENSOR NETWORK APPLICATIONS 27 4 1 SPECIFIC SENSOR NETWORK APPLICATION 8 23 42 EXTENSION METHOD OF THE NS 2 BASED SIMULATOR FOR SPECIFIC APPLICATION 20 5 CONCLUSION Ces dis A cn UL ee 35 SECUS 35 252 POTR PVO 36 6 REFERENCES 22 55 52 2 9 9 5 0 8 00 37 APPENDIX A BASIC WIRELESS NETWORK MODEL IN 5 2 39 AL ISWIOBHERNGOGILBDE 8 8 00 22 225 9 8 0 8 08 39 A2 NODE MOVEMENTS c 41 NETWORK COMPONENTS IN MOBILENODES 2000000000000000000000000 41 A4 DIFFERENT TYP
15. ENV Env HEAVY GEO j else if stremp LIGHT argv 2 ENV Env LIGHT GEO j else if strcmp SOUND argv 2 ENV Env SOUND WIRELESS SENSOR NETWORK SIMULATOR j else if stremp 05 argv 2 ENV Env 05 else fprintf stderr Unknown Env sensed s Continueing argv 2 j return TCL OK j else if stremp argvl1 target 0 tel Tel instanceO tcl evalf s set node this name tcl evalf Xs set ifq 0 tcl result 0 ifqueue PriQueue TclObject lookup tcl result return Agent command argc argv j else 4 return TCL OK j j return Agent command argc argv j Constructor ENV ENV nsaddr t id Agent PT ENV htimer this Hello Interval 1 Env TEST ENV 10 envDebugValue 0 SetDebugLevel 0 OpenDebugLog tempenv index id seqno 0 logtarget 0 smoothQueueLength 0 void ENVHelloTimer handle Event 1 if doSchedule Scheduler instance schedule this amp intr 0 doSchedule 0 j 48 APPENDIX B IMPLEMENTATION CODES FOR WSN CLASSES jitter 0 01 Random uniform jitter helps avoid collisions doSchedule 1 agent gt emanate Scheduler instance schedule this amp intr agent gt Hello Interval jitter B2 Environment Module Emanate ENV emanate need to add wrap around functionality to both th
16. The event scheduler and the basic network component objects in the data path are written and compiled using C to reduce packet and event processing time These compiled objects need the OTcl linkage to create a matching OTcl object for each of C objects to be able to work with OTcl interpreter NS 2 1s a free software which can be downloaded from 1 It can run both in Unix and Windows But to run in Windows it requires installing Cygwin 7 to set the computer environment as UNIX environment Details can be found in 8 9 10 and 11 BACKGROUND AND RELATED WORK 2 3 Related Work The related works of wireless sensor networks simulation are discussed in this section 2 3 1 Wireless Sensor network simulator They are several simulators that have been used in sensor network research In this part we discuss some simulators that can be used to evaluate the wireless sensor networks SensorSim Sensorsim 12 which has been built on NS 2 is a simulation framework for sensor networks It provides sensor channel models energy consumers lightweight protocol stacks for wireless micro sensors scenario generation and hybrid simulation The sensor channel models the dynamic interaction between the sensor nodes and the physical environment At each node energy consumers are said to control the power in multiple modes to efficiently use the power and prolong the nodes lifetime But this simulator is no longer developed therefore no mo
17. When the user node receives these detected data 1t analyzes the position where enemies attack by using the identity numbers of sensor nodes which send these detected data to it 4 1 2 Chemical gas cloud detection application model The chemical gas cloud detection application 1s very important for the industries which use the chemical gas as one of power sources Since some chemical gas is hazardous for people the sensor surveillance is needed to detect this gas before it emanates to the wide area The chemical eas cloud detection model application 1s shown below x X X x X O Chemical gas Environment Node X Sensor Node Chemical gas cloud X X Pd x X User node High intensity of chemical gas cloud X X X X Medium intensity of chemical gas cloud low intensity of chemical gas cloud X X Figure 4 2 The sensor network model used for the chemical gas cloud detection application This model assumes the group of environment nodes as the chemical gas cloud These environment nodes move together in the same direction The sensor nodes in this application are fixed in the position given by users These sensor nodes use the threshold values to define the intensity of the chemical gas cloud For example the threshold value 1 15 used for a high intensity 0 5 is used for a medium intensity and 0 05 is used for a low i
18. com accessed 25 May 2005 5 M Greis Tutorial for the Network Simulator NS http www isi edu nsnam ns tutorial index html accessed 25 May 2005 9 J Chung M Chaypool NS by Example WPI Worcester Polytechnic Institute Computer science http nile wpi edu NS accessed 25 May 2005 10 E Altman T Jimenez 5 Simulator for beginners http www sop inria fr maestro personnel Eitan Altman COURS N5 n3 pdf accessed 25 May 2005 11 The Network Simulator ns 2 Documentation http www isi edu nsnam ns ns documentation html accessed 25 May 2005 12 P Sung A Savvides M B Srivastava Simulating networks of wireless sensors Simulation Conference 2001 Proceedings of the Winter Volume 2 9 12 December 2001 pp 1330 1338 13 J Sim Tutorial http www j sim org accessed 25 May 2005 14 GloMoSim User Manual Global Mobile Information Systems Simulation Library UCLA Parallel Computing Laboratory http pcl cs ucla edu projects glomosim accessed 25 May 2005 27 WIRELESS SENSOR NETWORK SIMULATOR 15 S Sundresh K Wooyoung G Agha SENS a sensor environment and network simulator Simulation Symposium 2004 Proceedings 37th Annual 18 22 April 2004 pp 221 228 16 P Levis Lee TOSSIM A Simulator for TinyOS Networks Computer Science Division University of California Berkeley California 17 September 2003 17 P Levis N Lee M Welse D Culle
19. mentioned in chapter 4 can be done by using our proposed extension method While programming the software for the user to analyze the received data for its target is one of the interesting works For some specific applications the implementation of a new routing protocol is needed The information concerning the implementation of a new protocol can be found in 23 Furthermore one of the challenging works is to make a new sensor network simulator which supports the simulation in the high level application This new simulator should also be possible to apply for other applications 1n easy ways of implementations 36 REFERENCES 6 References 1 The Network Simulator ns 2 Information Science Institute USC Viterbi School of Engineering http www 1si edu nsnam ns accessed 25 May 2005 2 LF Akyildiz W Su Y Sankarasubramaniam E Cayirci A survey on sensor networks IEEE Communications Magazine August 2002 3 P Bonnet J Gehrke P Seshadri Queryring the physical world IEEE Personal Communications October 2000 pp 10 15 4 Flood Warning Technologies http www alertsystems org accessed 17 December 2005 5 Andersson M Sandberg L Urszuly Open Secure Office Project Master s Thesis in Computer Systems and Electrical Engineering Halmstad University January 2005 6 NAM Network Animator http www isi edu nsnam nam accessed 25 May 2005 7 Cygwin User s Guide http www cygwin
20. need to create a new class which can be called sensorappdata which is extended from the appdata The sensorappdata class 15 needed to contain the sensor data structure for general environment data and some methods like pointing the user data inserting the sensor data in array etc Required by different sensor application we need to generate a new class tempappdata which is inherited from the sensorappdata to specify the sensor data Step 2 Transmit sensor data in the sensor module Since ADU is similar to a Packet unit but has something different as we discussed above thus in the extension we need to modify the sensoragent to support the transmission of the sensor data from the sensor agent to the sensor application which is attached in the senor node To communicate with the user node via wireless channels a new agent wirelessagent which supports to transmit the sensor data 1s needed Depending on the service required we can inherit this new agent from UDP or TCP We need to modify the existing sensorapp class to support the sensor data and basic functions to deal with these data We can rewrite the process and precess data to pass the sensor data between sensor applications For the sensor node we also give the basic functions to deal with the sensor data such as filter and compare which required to process these sensor data and send them down to the wirelessagent Step 3 Deal data in the user module User module contains a new user agent
21. not support the wireless sensor network the Naval Research Laboratory group 20 has extended some components from the wireless network in NS 2 to be used with the wireless sensor network Unfortunately this project was based on the network simulation version 2 1b9a NS 2 1b9a which 1s the old version of the NS and that cannot be used in the new version NS 2 28 which has more components to support the networks than NS 2 1b9a has Our implementation of the sensor network in NS 2 28 15 based on the Naval Research Laboratory group The process of implementation is divided into two main processes adding the wireless sensor network classes and modification codes in NS 2 28 The overview of this implementation is as follows 12 IMPLEMENTATION OF NS 2 28 BASED WSN SIMULATOR NS 2 28 common enviroment makefile packet h env h mac env packet h mac cc env cc wireless phy cc debug h cc wireless phy h sensornet tcl lib ns lib tcl sensoragent h ns mobilenode tc sensoragent cc ns namsupp tcl trace sensorapp h cmu trace cc sensorapp cc cmu
22. start with a leading N Ni node id Nx node s x coordinate Ny node s y coordinate Nz node s z coordinate Ne node energy level NI trace level such as AGT RTR MAC Nw reason for the event Packet information at IP level This field starts with and the details are Is source address source port number _ Id dest address dest port number It packet type I packet size If flow id unique id Iv ttl value 44 APPENDIX A BASIC WIRELESS NETWORK MODEL IN NS 2 Next hop info This field which describes next hop info starts with H Hs 1d for this node Hd id for next hop towards the destination Packet info at MAC level This field which describes MAC layer information starts with M Ma duration Md dst s Ethernet address MS src s Ethernet address Mt Ethernet type Packet info at Application level This field describes the packet information at the application level which consists of the type of application like ARP TCP and different types of routing protocol like DSDV DSR AODV etc This field start with P arp For ARP whose details are Po ARP Request Reply Pm src mac address Ps src address Pa dst mac address Pd dst address P dsr The DSR routing protocol details are Pn how many nodes traversed Pq routing request flag Pi route request sequence number Pp routing reply flag Pl reply length
23. these existing 7 WIRELESS SENSOR NETWORK SIMULATOR components or write the new one for their applications network models sensor capabilities and environments SENS features the application portability to enable direct portability between the simulator and real sensor nodes TOSSIM TOSSIM 16 1s a discrete event simulator built specifically to simulate the Berkeley MICA mote hardware platform running applications built on TinyOS wireless sensor networks Instead of running a TinyOS application on motes users can compile it in the TOSSIM framework which runs on a PC By running on a PC users can test the application in a controlled environment and develop their TinyOS codes by using debuggers and other development tools TOSSIM supports four key requirements of a TinyOS simulator which are scalability completeness fidelity and bridging TOSSIM is sufficient for the evaluation of a high level application but it is not sufficient for low level protocol such as MAC Due to TOSSIM mainly focuses on the TinyOS sensor networks it should not be used for absolute evaluations in the real world OMNeT OMNeT Objective Modular Network Test bed in C 18 is a wireless sensor network simulator which is based on the discrete event simulation framework As the OMNeT model collects hierarchy modules it is possible to capture the complex system These modules are separated into two types which are simple and compound Simple modules are prog
24. trace h queue priqueue cc Figure 3 6 The implementation process of adding class in right side and modification files in left side 3 3 1 Wireless Sensor Network Classes The wireless sensor networks are classified into three different types 3 3 1 1 Environment Class The environment class consists of environment nodes environment agents environment routing protocols the pulse rate etc The environment node needs to be attached to the environment agent to enable the node to communicate with the sensor channel To broadcast the environment packet the environment routing protocol and the pulse rate are required The environment routing protocol is used to find the path and the pulse rate is used to indicate how often the environment node broadcasts the environment packet 13 WIRELESS SENSOR NETWORK SIMULATOR 3 3 1 2 Sensor Agent Class The sensor agent class consists of sensor nodes sensor agents UDP TCP agent etc The sensor node is attached to the sensor agent to communicate with the sensor channel for consuming the sensing packet On the other hand the sensor node is attached to a UDP or TCP agent to communicate with the wireless channel which receives the constructed packet sent down from the sensor application 3 3 1 3 Sensor Application Class The color and the rewriting functions are used in this class The color function defines the different states of the sensor nodes by using different colors and the rewriti
25. useragent which is inherited from UDP or TCP basic agent to support the sensor data and a new application userapp This application executes the 33 WIRELESS SENSOR NETWORK SIMULATOR main function of the sensor network like measuring the environment temperature as it was discussed above Unfortunately since the time 1s limited we can only propose the sensor network application models and the methods how to extend the environment and real data transmission modules which can be carried out in the future 34 CONCLUSION 5 Conclusion In this work the structure of wireless sensor networks is defined and then NS 2 28 15 implemented by adding three sensor network classes environment sensor agent and sensor application classes and modifying the existing classes in NS 2 28 to support the wireless sensor network Three different types of mobile nodes namely environment sensor and user nodes are defined in the wireless sensor network The environment class is added to NS 2 28 for the environment node to generate the periodic pulses and send the packets to the sensor node the sensor agent class is added for using the agent to communicate with environment and user nodes and the sensor application class 1s added for the color and rewriting functions After implementing the NS 2 based simulator the extension of simulator for specific sensor network application is discussed The enemy surveillance the chemical gas cloud detection and th
26. 0 400 500 Number of sensor nodes in the network Figure 3 10 Packet delivery ratio of DSDV and AODV with different number of sensor nodes With the testing condition as mentioned above DSDV has a better performance in the average end to end delivery time while AODV has a better performance in the packet delivery ratio The simulation in this part is only the example of using the implemented protocol to test routing protocols These results are not the conclusion of these two protocol comparison since we neglect some different conditions of these protocols such as the speed of node mobility and the size of sensor nodes should be used more different sizes 26 EXTENSION OF SIMULATOR FOR SPECIFIC SENSOR NETWORK APPLICATIONS 4 Extension of Simulator for Specific Sensor Network Applications After extending NS 2 28 to support the wireless sensor network simulation the simulator is extended for use in a specific sensor network In this chapter the specific sensor network application models and the method to extend the NS 2 based simulator for specific sensor network applications are discussed 4 Specific Sensor Network Application Models This part identifies the specific sensor network application models The sensor network applications such as enemy surveillance chemical gas cloud detection and detection of environment temperature are discussed 4 1 1 Enemy surveillance application model The enemy surveillance is one important app
27. ES OF ROUTING AGENTS IN MOBILE NETWORKING cerne 43 AS TDRACESEPPOR D 21 2 2 5218225 555 2252 2828225 559122297291285 0 0 80 0 5 one 1 2 8 2 0 0A IIIS ARI de denies f acsmUunt 43 AGO WIRELESS 063 EIS leo ISTE ASI sinunt 43 APPENDIX B IMPLEMENTATION CODES FOR WIRELESS SENSOR NETWORK CLASSES 47 ENVIRONMENT MODULE COMMANDO tori vada Dn pa ei ek es 47 B2 ENVIRONMENT MODULE EMANATE 49 iINSSMIODBIEENODE ICT 50 OMUSTRACE ILC URGE 32 APPENDIX C EXAMPLE TCL CODES FOR TESTING ROUTING PROTOCOLS ce ee eee eee eoee 55 vi INTRODUCTION 1 Introduction In recent years advance in micro electro mechanical systems MEMS which are the integrations of mechanical elements sensors actuators and electronics on a common silicon substrate through micro fabrication technology and have enabled low cost and low power in electronics and wireless communication technology enabled tiny sensor nodes to communicate in short distance Wireless Sensor Networks WSNs comprise numerous tiny sensor nodes that are deployed in spatially distributed terrain Each sensor node is endowed
28. NSMIT FREQ seconds since this sensor node transmits the last sensor data report to the sink This timer prevents nodes from transmitting a sensor data report every time they hear an environment packet which would be very bad in the simulation where there are a lot of environment nodes The timers have two functions SendTimer expire Event e When the node alarm is activated it sends the MESG SIZE bytes message every TRANSMIT FREQ seconds to the sink node via the attached transport agent udp tcp etc SilenceTimer expire Event e This function defines what should happen when the sensor is no longer detecting the environment packet Such as turning off the node alarm changing the node color to the silent color and cancelling the sent timer In the sensor module there are configurable parameters which can setup in the simulation such as SILENT DIS ABLE COLORS MESG SIZE and TRANSMIT FREQ 19 WIRELESS SENSOR NETWORK SIMULATOR 3 3 3 Modification in NS 2 28 As shown in Fig 4 5 the modification details of files in NS 2 28 are explained follow common packet h In the NS each packet has a unique type to associate with a specific protocol such as UDP AODV TCP etc In Env class a new protocol is created to broadcast the env packet so it is required to add the new packet type to the packet h header file To add this new packet type the following command lines are put in the packet h file add define HDR
29. a TCP connection as a FIFO pipe Therefore for the sensor network application we need to drive a new ADU which calls AensorAppData from the base class The new ADU class should contain a general data structure for all sensor application data which are not only a unique data structure of the specific sensor application like the temperature data structure As we think the normal sensing information like the temperature information is short we use the UDP agent to send this information This process is defined below class SensorAppAgent public Agent public SensorAppAgent virtual void recv Packet Handler virtual void send int realsize AppData data protected int off inv CON OF 59 In lines4 5 the method recv Packet Handler is overridden to extract the user data and new send int AppData is provided to include the user data in packets In send the following code can be used to write the user data from AppData to the user data area in a packet Packet pkt allocpkt data size hdr inval xih hdr inval pkt gt access off inv Ih sizeO data 2size0 char char pkt accessdata data gt pack p O1 A GW N m In recv the following code can be used to read the user data from the packet and to deliver it to the attached sensor application 1 hdr inval ih hdr inval pkt gt access off inv 2 SensorApp app gt data ih
30. a new module with NS 2 can be found in 21 4 2 2 Extension of real data transmission module Since we need to use the real user data the main problem 15 how to create the real user data and transmit them NS 2 all applications are described as virtual applications which do not actually transfer their own data in the simulator including the size and the time when data are transferred As we shown in here when we do some specific sensor network simulations which are not only the network behaviours that we want to know but also how the functional of the specific sensor network is we need to transfer the real application level s data The method to implement these modules in the extension of NS 2 28 1s a big challenge for us who have the limitation of programming experience and time to implement Below are some ideas and general steps to implement these modules In order to transmit the application level data in NS 2 we need a uniform structure to pass these data among applications and send them down from applications to transport agents To do this three major components which are a representation of a uniform application level data unit ADU a common interface to pass data between applications and two mechanisms to pass data between applications and transport agents such as UDP agent and TCP agent are needed The basic components that can be used to generate the user data are 4 2 2 1 Application level Data Unit ADU The function of
31. amined and then the NS 2 28 based wireless sensor network simulator is implemented Finally an example of using this simulator to test routing protocols 15 given 3 1 Basic Structure of Wireless Sensor Networks Wireless networks consist of numerous mobile nodes which communicate with each other via wireless channels while 1n wireless sensor networks these mobiles nodes are attached with sensors to sense the physical target and processors to generate data packets from sensing data and transmit them to their neighbors Mobile nodes in wireless sensor networks are classified into two types sensor and sink nodes Sensor node This 15 a mobile node moving freely to monitors the physical environment Once it detects its physical target it generates a data packet and sends it to the sink node via the wireless channel The processor in the sensor node may be set the threshold value to compare with the detected data before it generates and sends a data packet Sink node This node collects all data packets from sensor nodes Users use these collected data to analyze their targets Sink Node User Sensor Field Sensor Nodes Figure 3 1 The basic structure of wireless sensor networks WIRELESS SENSOR NETWORK SIMULATOR 3 2 Simulation Model of Wireless Sensor Networks To simulate wireless sensor networks the simulation model 1s shown below Temperature data Ve o eS zt User Enemy movemen
32. an ADU is similar to a Packet unit function which is needed to pack user data including the user data area of an NS packet by an Agent into an array In the current NS 2 the agent 15 not supported by current Agents so we must derive new agents to accept the user data from applications UDP or use an agent wrapper TCP Compared with Packet ADU provides this functionality in a different way In Packet a common area 15 allocated for all packet headers an offset is used to access different headers in this area In ADU this is not applicable because some ADUS allocate their space dynamically according to the availability of the user data The below codes show the abstract base class of all ADU 1 class AppData 2 private AppDataType type ADU type 30 EXTENSION OF SIMULATOR FOR SPECIFIC SENSOR NETWORK APPLICATIONS 4 public 5 struct hdr 1 6 AppDataType type 1 3 8 public 9 AppData char b 10 assert b NULL 116 type hdr b gt type_ 12 j 9 virtual void pack char buf const In line13 pack char buf is used to write an AppData object into an array and AppData char b is used to build a new AppData from a serialized copy of the object in an array 4 2 2 2 A common interface to pass data between applications The base classes of Application and Process allow applications to pass data or request data between each other The process which enables Application to link Process 1s 1 clas
33. andom movement Ld source orig randommovement Himport the 49nodes file which create 49 sensor and one user nodes source orig 49nodes 57 WIRELESS SENSOR NETWORK SIMULATOR Attach the sensor agent to the sensor node and build a conduit thru which H recieved Env packets will reach the sensor agent s recv routine H attach a Sensor Agent i e sensor agent to sensor nodes for set i 10 i lt 59 j incr i set sensor i new Agent SensorAgent ns attach agent node i sensor i H specify the sensor agent as the up target for the sensor node s link layer configured on the sensor interface for set i 10 i lt 59 incr i 4 node i set 11 1 up target sensor i ns at 0 01 sensor i start setup UDP connections to user node and attach sensor apps set sink 0 new Agent UDP ns attach agent node 59 sink O for set 1 10 i lt 59 j incr i set srcO i new Agent UDP ns attach agent node i srcO i ns connect srcO i sink O set 0 i new Application SensorApp 0 i attach agent srcO i j for set i 10 i lt
34. architecture is shown below User User Node Application Network Stack Network Layer MAC Layer Physical Layer Wireless Channel Figure 3 5 The user node model architecture 11 WIRELESS SENSOR NETWORK SIMULATOR The user node which consists of the application layer and the network protocol stack network MAC and physical layer receives sensor reports and sends them up to the application layer Communication model The wireless sensor network communication can be classified into three types Environment Sensor Communication This is a one way communication for broadcasting a physical environment data from the environment nodes to the sensor nodes The communication channel between environment and sensor nodes 15 defined as a sensor channel Sensor Sensor Communication This is a two way communication between the sensor nodes These traffics are used to collect signal processing of sensor events in the network before they report them to the user node Sensor User Communication This is a two way communication the one from sensor to user 1s used to transmit sensor reports to the user and the other which is from user to sensor 1s used to transmit user commands and queries to the network The communication channel between sensor and user nodes 15 defined as a wireless channel 3 3 Implementation Sensor Network in NS 2 28 As the network simulator NS does
35. de switches the status between activity and silent 1 int SensorApp change color char color 2 if DISABLE COLORS 9 return 0 4 if stremp newcolor color 0 amp amp STARTED 5 Tcl amp tcl Tcl instance Q 6 tcl evalf s set node sensor agent gt T const char node object tcl result 8 Tcl instance evalf s color 48 node object color 18 IMPLEMENTATION OF NS 2 28 BASED WSN SIMULATOR 9 newcolor color make pointers equal 10 j return 0 125 3 In lines2 and 3 if the node color is desired to illustrate energy levels instead of sensor activity status then it will use DISABLE COLORS to turnoff the color change function in the sensor application In lines 4 to 10 these codes are used to change the node color during the simulation and report it to the NAM tracing file Process sensor data The SensorAgent function calls this function after it detects some environment packet and periodically sends SIZE bytes of data to the sink node 1 void SensorApp process sensor data int size Packet env pkt 2 change color 3 if alarm DEACTIVATED a agent gt send MESG SIZE 5 send timer resched TRANSMIT FREQ 6 j 7 alarm ACTIVATED 8 silence timer resched SILENT 9 j Lines 3 to 6 illustrate when the sensor node is active the sensor node only forwards the packet Timer The timer expires after TRA
36. e environment temperature detection models are presented Finally the extension method of the NS 2 based simulator for specific applications are proposed This method includes the extension of environment and real data transmission modules Unfortunately since the time is limited and 1s much spent in finding this extension method the extension of this simulator can be done in the future 5 1 Discussion Since we are very new in the fields of wireless sensor networks and the network simulation we spent a lot of time to learn how to write OTcl script in NS 2 and solve some NS 2 problems such as installation problems Valuable information was obtained from 22 However we have some comments on NS 2 and the sensor network simulators Although NS 2 1s the most widely used for the network simulator it does not support directly the wireless sensor network and to use this simulator with the sensor networks some implemented modules are needed Unfortunately these implemented modules can be used only for the version of NS 2 that users implement but they can not be reused in the different versions Furthermore some applications in the wireless sensor networks require some new modules for generating real data packets or new routing protocols However NS 2 is an object oriented design which introduces much unnecessary interdependence between modules This interdependence causes the implementation of new modules extremely difficult for users who do not ha
37. e seqno sending and teh recieving side Packet Packet allocQ struct hdr cmn ch HDR CMN p struct hdr ip ih HDR IP p struct hdr env main mh HDR ENV p struct payload msg payload ENV PAYLOAD p sizeof struct hdr env main in bytes DMSG 8 4 segno being packed seqno fflush stdout mh gt pck length msg payload gt size sizeof struct hdr env main in bytes msg payload gt msg oAddr here addr msg payload msg size sizeof struct payload will point over be careful msg payload msg seqno seqno msg payload gt Env ENV Env ch gt ptype ih gt saddr _ _ ih gt daddr IP BROADCAST ih gt sport ENV PORT ih gt dport ENV PORT ih gt ttl 1 DMSG 8 sending Hello from d at 4f n here addr CURRENT TIME fflush stdout Scheduler instance schedule target p 0 0 target _ gt EnvAgent j 49 WIRELESS SENSOR NETWORK SIMULATOR B3 ns mobilenode tcl set sensing energy for sensor nodes Node MobileNode instproc setPs val j self instvar netif_ if into exists netif 1 4 netif 1 setSensePower val j setup up link layer mac layer network interface and physical layer structures for a sensor node Node MobileNode instproc add ENVinterface channel pmodel lltype mactype qtype qlen iftype anttype inerrproc outerrproc fecproc self ins
38. ed to the electrical appliances such as air conditioner computer refrigerator etc These sensor nodes can communicate with each other or with the users who live outside this network The users can control these appliances via the internet or satellite network Open secure office The sensor nodes are attached to the valuable equipments such as laptops printers PDAs etc Each room has a local base station and at the entrance door the main base station 15 installed When someone tries to move the equipment the sensor at that equipment which could be a vibration sensor sends an alarm to its local base station which will send a command to the camera to take a picture of that room Or when the equipment 15 moved near the entrance door the main base station detects an alarm and sends a command to lock the door automatically BACKGROUND AND RELATED WORK 2 2 Network Simulator NS The network simulator NS which 1s a discrete event simulator for networks 1s a simulated program developed by VINT Virtual InterNetwork Testbed project group A Collaboration among USC ISI Xerox PARC LBNL and UCB It supports simulations of TCP and UDP some of MAC layer protocols various routing and multicast protocols over both wired and wireless network etc The basic structure of NS 2 15 f NS B OTcl Tcl Interpreter Simulation Results OTcl Script Simulation Program C Library NS Simulator L
39. eporting sensing data packet to the sink node etc The sensor node model architecture is shown follow Sensor Node a Sensor Application Power Model S N Battery Sensor Stack 1 Sensor Stack 2 Network Stack Network Layer Sensor Layer Sensor Layer CPU MAC Layer Physical Layer Physical Layer Radic 4 2 Physical Layer L J E 2 C N Sensor Channel Wireless Channel Ns S S Sensor Channel AL Figure 3 4 The sensor node model architecture The sensor node model consists of one network protocol stack and one or more sensor protocol stacks depending on different types of environment targets The task of the sensor protocol stack is to detect and process the detected data received from environment nodes on the sensor channel and forward them to the application layer The application layer will process and transmit them to the user node in the form of sensor reports via the wireless channel One important part of the sensor node besides these two types of protocol stack is a power model which consists of an energy provider such as the battery and energy consumers such as CPU and Radio User node model This model makes an interface between the sink node and users Users use sensing data from the sink node to analyze their targets The user node model
40. figure 4 3 to detect each temperature area In this model the unknown temperature A B and C can be approximated and calculated from the neighbor area temperature which is detected by sensor nodes For example the temperature can be forecasted from the earlier detected temperature where A could be 20 degrees the temperature B 15 the average of 11 and 12 which is 11 5 degrees and temperature C can be calculated by finding the average temperature of the closed area temperature 19 24 and 25 degrees which 1s 22 67 degrees 4 2 Extension method of the NS 2 Based Simulator for Specific Applications In this part two main extensions of the NS 2 based simulator for specific sensor network application are discussed 29 WIRELESS SENSOR NETWORK SIMULATOR 4 2 1 Extension of environment module To simulate sensor network applications the environment module is needed to extend to support specific application models The main task of this module is to provide the environment data for the simulation In the enemy surveillance and the chemical gas cloud detection applications this module provides the amount of environment nodes assumed as enemies and chemical gas and the mobility of environment nodes while in the environment temperature detection application this module provides the temperature in each area to environment nodes The extension of this module can be written in C and then interface it with NS 2 The information how to interface
41. hbor they use their data processing component to find out the simple computations and select the required data to transmit With these features the wireless sensor network can be used in many applications In this part some sensor network applications are discussed 2 2 1 1 Military applications The initial wireless sensor network is to be used in the military applications Since sensor nodes are low cost destruction of some nodes by hostile actions in the battlefields may not affect a military operation The features of robustness self organizing and fault tolerance make sensor networks appropriate for military use Distributed sensing has the advantages of being able to provide redundant and hence highly reliable information on threats as well as the ability to localize threats by both coherent and incoherent processing among the distributed sensor nodes Examples of the military applications of sensor networks are monitoring army equipment and ammunition 2 and enemy surveillance Monitoring army equipment and ammunition Every troop equipment vehicle and critical ammunition is attached with sensors In the battlefield the commanders can monitor the status of their armies equipment and ammunitions from reported data which are generated constantly by sensors and forwarded to the commanders Enemy surveillance The sensor network deploys heterogeneous collections of sensors capable of observing and reporting on various dynamic prope
42. he development lifetime In our project NS 2 1 is chosen as our simulation environment because it is the most widely used network simulator NS 2 has several key benefits which suit for doing the simulation It provides extensive support for simulating TCP IP Routing and multicast protocols over wired and wireless network It provides a lot of standard modules to be used in sensor network It is an object oriented design which provides a lot of documents t uses Tcl to specify the components and OTcl to glue them together 1 1 Goals As wireless sensor networks have been used in a lot of applications monitoring nodes in the network are needed for some applications The important functions which need to be monitored are the communicated data between each node the movement of nodes etc The goal of this project is to design a simulator which can be used to monitor wireless sensor and actuator networks on a useful level to evaluate different functions cooperation patterns network topologies and physical space time and event scenarios Though there are a lot of routing protocols which can be used in the wireless sensor networks this simulator is used to test WIRELESS SENSOR NETWORK SIMULATOR different routing algorithms as one part of simulation Furthermore this simulator is extended for the simulation of sensor network applications such as enemy surveillance application and chemical gas cloud application The results of the simula
43. ibrary Event Scheduler Objects Network Component Objects Network Setup Helping Modules Plumbing Modules A Figure 2 1 The basic structure of NS To setup and run a simulation a user writes an OTcl script which is a simulation program to initiate an event scheduler set up the network topology using the network objects and plumbing functions in the library and to tell traffic sources when to start and stop transmitting packets through the event scheduler When NS 2 which works as OTcl interpreter receives the OTcl script it will set environment parameters following the received script If a user wants to make a new network object it will be easy to make a compound object from the object library and plumb the data path through the object rather than write a new one When the simulation is finished the simulation results are produced in one or more text based output files that contain detailed simulation data which can be used to analyze directly or can be used in the graphical user interface Network Animator NAM 6 This graphical user interface shows the simulation result in an easy way WIRELESS SENSOR NETWORK SIMULATOR Views Analysis CAcygqwindiomeiBallinrl sensaorsim 2 27vexampleiplhenom 6AODV nam e o 4 T TIAHE dl a a n a bcn n bn n PPP m b a n n Figure 2 2 Network Animator NAM The language that is written in NS 2 is not only OTcl but also
44. ifq ifqLen val ifglen antType val ant V propType val prop phyType val netif channel chan_1_ topoInstance topo agentTrace ON routerTrace OFF macTrace ON movementTrace OFF This procedure creates a Mobilenode comprising adhoc routing protocol network stack consisting of a link layer mac layer an interface queue a network interface with an antenna using defined propagation model channel topography and different tracing levels agent router mac and movement turned on or off 39 WIRELESS SENSOR NETWORK SIMULATOR The schematic of a Mobilenode 1s shown below Go Src Sink IPaddress port 255 demux entry addr Rey demux RT agent defaulttarget_ DSDV DSR e target y ARP uptarget_ arptable Address LL Resolution r Protocol downtarget_ interface Queue downtarget_ 802 11 TDMA X S MAC uptarget_ downtarget_ uptarget_ NetlF Radio Propagation m Network Model Interface downtarget_ uptarget_ Channel Figure A 1 The schematic of a mobile node in NS 2 40 APPENDIX A BASIC WIRELESS NETWORK MODEL IN NS 2 A2 Node Movements Although NS 2 supports the movement of Mobilenodes in a three dimensional topology the Mobilenode is normally assumed to move only two di
45. ion to analyze the details of networks The wireless simulations use two different trace formats which are described in this part by using the output traces A6 1 Normal trace format An example of a line in output trace is 5 009402153 2 AGT 0 cbr 230 13a 2 1 800 1 0 2 0 30 2 0 The first field 1s a letter which can be one of the types r s f and D for received sent forwarded and dropped respectively It can be M when a node has a movement a location The second field 1s the time in second The third field 1s the node number The fourth field is the type that the packet that can be one of MAC and MAC indicates a MAC layer AGT indicates a transport layer packet RTR indicates a routed packet and IFQ stands for the event which relates to the interference priority queue The number represents after the dashes 1s the global sequence number of the packet The next field concerns the information of the packet type tcp ack or udp The next number is the packet size in bytes The four numbers in the first bracket stand for the MAC layer information The first hexa decimal number specifies the expected time in seconds to send this data packet over the wireless channel The second number is the MAC 1id of the sending node The third number is the MAC id 43 WIRELESS SENSOR NETWORK SIMULATOR of the receiving node The last number stands for the MAC type while the number
46. lication using in the military application An amount of sensor nodes are deployed in the wide environment area which may be attacked from enemies These sensor nodes are attached with ground vibration sensor When enemies move into the sensor area these sensor nodes will detect the ground vibration and generate the detected data packet sending to the sink node which is interfaced with the commander The enemy surveillance application model is shown below 6 Sensor Area 2c x lt x S X X x ps X 2 xX D x 2 x E xo x e 0X X x x x Xi x wad 4 X pu 57 x a v Environment Node d rs 2 lt Sensor Node X Xu 52 X ps x x ps Commander C e J User node Figure 4 1 The sensor network model used for the enemy surveillance application In the simulation model enemies are assumed as environment nodes moving into the observe sensor area The sensor nodes are coordinated the fix position in the sensor area and are given the identify numbers from the commander The behaviour that the sensor nodes detect the broadcasted ping from environment nodes is assume as the sensor nodes detect the ground 2l WIRELESS SENSOR NETWORK SIMULATOR vibration from enemies moving in the sensor area Once these sensor nodes detect ping they generate data packets and send them to the user node
47. ls Routing protocol with D5DV or AODV 3 4 4 User node model The user node collects all the sensor reports from the sensor nodes The user node model consists of Link layer MAC layer with the 802 11 type Interface queue with the DropTail PriQueue Interface queue length with maximum 50 packets in the interface queue Antenna with the Omni directed Antenna Propagation model with the TwoRayGround Network interface with the WirelessPhy Channel with the Wireless channel Routing protocol with DSDV or AODV 24 IMPLEMENTATION OF NS 2 28 BASED WSN SIMULATOR 3 4 5 Communication model To receive the detected data from the environment nodes via the sensor channels the sensor nodes need to attach to the sensor agents to communicate with sensor channels For the communication between the sensor nodes and the user node via wireless channel the sensor nodes also need to attach with the UDP agents whereas the user node need to attach to the sink agent 3 4 6 Mobility model As mentioned above the sensor and the user nodes are fixed We create the random movement only for the environment nodes by using the Setdest function in NS 2 The starting positions of the environment nodes are randomly initiated a square area of 1000m x 1000m and they move randomly to their random destinations with the speed between 0 20 m s When they reach their destination they will move to the next random destination until the simulati
48. mensional in X Y planes and Z plane 15 always equal to 0 The basic mechanism to induce movement in Mobilenodes from the starting position is to give their future destinations To set the Mobilenode movement the following OTcl codes are used nodesetX x1 node set Y yl nodesetZ zl ns at time node setdest x2 y2 speed First create the starting position x1 yl then give the sufficient time and moving speed for Mobilenode to move towards the destination x2 y2 The node movement generator is available in ns indep utils cmu scen gen setdest The node movement file can be created by using the following codes setdest n num of nodes p pausetime s maxspeed t simtime x maxx y maxy gt outdir movement file The code creates a node movement scenario which consists of n nodes and moves with maximum speed s with an average pause between the movements which is 2 seconds The topology boundary is defined by x and y and the simulation time is defined by t For the traffic scenario random traffic of TCP and CBR connections between Mobilenodes can be generated by using a traffic scenario generator script which can be found in ns indep utils cmu scen gen and the file is cbrgen tcl The random traffic pattern can be created by using the following codes ns cbrgen tcl type crbltcp nn nodes seed seed mc connections rate rate To create a random traffic pattern we have to define the
49. nds an additional packet to the same destination the earlier buffered packet will be dropped When it knows the next hop address the packet will be inserted into the interface queue The class of ARPTable is implemented in ns arp cc h and ns tcl lib ns mobilenode tcl Interface Queue This class gives a priority queue to routing protocol packets and inserts it on the head of the queue It also supports the running of a filter queue over all packets in the queue and removes those with a specified destination address The class of PriQueue 1s implemented in ns priqueue cc h MAC Layer The MAC layer uses the RTS CTS DATA ACK pattern for all unicast packets and sends out DATA all broadcasting packets The class of 802 11 is implemented in ns mac802_11 cc h Network Interfaces The network interface layer 1s used by Mobilenode to access the channel The interface stamps each transmitted packet header with the meta data related to the transmitting interface such as transmission power and wavelength This meta data 1s used by the propagation model in the receiving network interface to determine whether the packet has enough power to be received by the receiving node The implementations are in ns phy cc h and ns wireless phy cc h Radio Propagation Model Friss space attenuation 1 r model is used for short distances and the Two Ray Ground 1 r model is used for long distances The implementation is in ns tworayground cc h
50. ng function allows the other people to implement their own application 3 3 2 Adding wireless sensor network classes 3 3 2 Environment Class This module contains the new environment packet type the environment agent and the environment packet emanating protocol The environment agents send periodic pulses through a node s wireless interface according to the period parameter specified in the Tcl script for example node 0 set ragent pulserate 5 which have no auditory faculty which means they don t listen and receive packets via attached sensor channel To simplify the environment emanating routing protocol we only broadcast the Env packet The main parts of the codes are Packet Types Env packet h file contains all data structures constants and macros related to these new packet types The codes are define TEST PHENOMENON 1 Hdefine CO 2 define HEAVY GEO 3 define LIGHT GEO 4 define SOUND 5 Hdefine HDR ENV p struct hdr env main hdr Hdefine ENV PAYLOAD p offset struct payload hdr env access p offset struct hdr env 1 static int offset 10 inline static int amp offset return offset O OO gt Or ee B5 Lr qe inline static hdr env access const Packet p 244 return hdr env p access offset 135 j 14 inline static hdr env access const Packet const int loffset 15 return hdr gt offset loffset l6 3
51. ntensity When these sensor nodes detect ping which is broadcasted by the environment node the behaviour that sensor nodes detect ping 15 assume as these sensor nodes detect the chemical gas cloud they compare the signal power of ping with threshold values to identify the intensity of the chemical gas cloud The closer sensor nodes to environment nodes give the higher signal power and higher intensity of the chemical gas cloud After sensor nodes define the intensity level of the chemical eas cloud they generate data packets and send them to the user node From these data users know where the chemical gas cloud 1s and intensity of the chemical gas cloud in that area 28 EXTENSION OF SIMULATOR FOR SPECIFIC SENSOR NETWORK APPLICATIONS 4 1 3 Environment temperature detection application model The simple environment temperature detection application model is shown below s 4 S k s iz m 5 s s s 5 C Environment Node Sensor Node User Node Environment Temperature A B C Unknown Temperature Figure 4 3 The sensor network model used for the environment temperature detection application This model defines static environment nodes to broadcast data packets which include the temperature in their areas while sensor nodes move in the same direction as shown in
52. nvironment packet and passes it to the sensor application it activates an alarm public variable in the NAM visualization tools changes the node color to red and at the same time the sensor application sends a sensor report of MESG_SIZE bytes to the sink node via a UDP or TCP connection once per TRANSMIT_FREQ seconds In the timeout period when the sensor node does not receive an environment packet the state of node changes to the silent state In NAM the node color 15 changed to green This application implemented in the sensorapp h cc TCL Hook Like the sensor agent Tcl hook is used to generate a new instance as a TCL object like Application SensorApp Start This function tells the sensor agent that the node has a sensor application attached and a pointer passed to this sensor application so the sensor agent can notify the sensor application when an environment packet is received void SensorApp start SensorAgent sensor agent sensor agent ptr sensor agent sensor agent ptr gt attach sensor app this STARTED TRUE alarm DEACTIVATED change color green 1 W Lines 2 to 4 tell the sensor agent that a new sensor application 15 attached Lines 5 to 6 initiate the parameters for change color function and set the sensor node color as green which means the node is in the silent state change color This function is used to change the color of the Tcl object nodes when the no
53. o support NS 2 where the old nam api set rate works but it 1s quite obscure The following codes are added in this file Add set r time parse rate self puts nam config t self now set rate ext r 1 21 WIRELESS SENSOR NETWORK SIMULATOR trace cmu trace h cc The CMUTrace class is used to export the important part of a packet to a simulation trace file name tr which is defined in the simulation Tcl script Since there 15 a new packet implanted to env_packet we need to describe this new packet format in this class The modified code of cmu trace h is added the under mentioned code while the modified code of cmu trace cc is shown in Appendix B4 Add void format env Packet p int offset asa private function queue priqueue cc NS 2 contains different queue algorithms Since there is a new Env type packet implemented it needs to choose a specific queue algorithm to associate with To modify this code the following code is added Add case PT ENV to the PriQueue recv function Makefile in Makefile is used to compile the OTcl object in NS 2 When new modules or components are added the corresponded object is needed to be added to the Makefile to build it In this extension we need to rebuild all these modified objects in the base NS 2 object and build new objects such as env o sensoragent o and sensorapp o The following codes are added in this file Add Enviroment evi o sens
54. on time is expired 3 4 7 Experiment scenario In this experiment the four and ten environment nodes are used in the model discussed above Testing by using ten environment nodes the sensor and the user nodes use the AODV routing protocol The environment nodes are set to broadcast the packets once they move into each sub space The time to run the simulation is 50 seconds After finishing the AODV routing protocol the sensor and user nodes are changed to use the DSDV routing protocol The simulation also runs in the same condition For testing with four environment nodes the AODV and the DSDV are also used in the same condition The interesting parameters in this experiment are the packet delivery ratio and the average end to end packet delivery time The formulae for the calculation of these two parameters are Recei P Packet delivery ratio 100 Sent _ Packets Tr Ts Average end to end packet delivery time 2 Number of Packets Where 7r The receive time Ts The send time 25 WIRELESS SENSOR NETWORK SIMULATOR 3 4 6 Results o 2 1 gt gt 5 t 100 200 300 400 500 Number of sensor nodes in the network Figure 3 9 Average end to end delivery time of DSDV and AODV with different number of sensor nodes Packet delivery ratio 96 100 200 30
55. op Propagation TwoRayGround radio propagation model set val netif Phy WirelessPhy network interface type set val mac Mac 802 11 type set val ifq Queue DropTail PriQueue interface queue type set val 11 15 link layer type set val ant Antenna OmniAntenna antenna model set val ifqlen 50 S max packet in ifq set val nn 59 number of mobilenodes set val rp AODV tt routing protocol set val x 1100 S grid width set 1100 grid hieght Queue DropTail PriQueue set Prefer Routing Protocols 1 H specify the transmit power Phy WirelessPhy set Pt 0 1 puts This is an AODV routing protocol testing in a sensor network Initialize Global Variables H set ns new Simulator set tracefd open 49A0DV tr w ns trace all tracefd set namtrace open 49A0DV nam w ns namtrace all wireless namtrace val x val set up topography object set topo new Topography 55 WIRELESS SENSOR NETWORK SIMULATOR topo load flatgrid val x val y Create God H set god create god val nn god off god allow to stop god num data types 1 Hconfigure sensor channel and wireless channel set chan 1 new val chan set chan 2 new val chan configure environment node set val rp ENV ENV routing protocol ns node config adhocRouting val rp val 11 macType val mac ifqType val ifq ifqLen val ifqlen
56. orAgent as an argument which represents the class hierarchy of this agent in a textual manner In lines 4 to 6 a function called create is implemented to return a new SensorAgent instance as a TclObject Recv This recv is invoked whenever the sensor agent receives an environment packet Every packet has a common header called hdr cmn defined in common packet h To access this header a macro like the one defined before is used for our own packet types and we use it at line 3 In lines 2 to 7 they check the sensor application whether it 1s attached to the agent if the sensor application 15 attached they will pass the environment packet to it void SensorAgent recv Packet pkt Handler if sensor app hdr cmn ch hdr cmn access pkt 1 3 4 sensor gt sensor data ch gt size pkt 5 j 6 j Attach sensor app This function received from the node s sensor application once the application receives a start command In line 3 it sets the sensor app variable to the sensor app parameter because this parameter hides class variables void SensorAgent attach sensor app SensorApp sensor app param 1 Ds 4 sensor sensor app param 4 j 17 WIRELESS SENSOR NETWORK SIMULATOR 3 3 2 3 Sensor Application Class The sensor application generates the sensor report to show when the corresponding sensor node detects the environment packet When the sensor agent receives the e
57. ornets sensoragent o sensornets sensorapp o V to generate the Tcl object 3 4 Example of Using the Simulator to Test Routing Protocols After implementing NS 2 28 based simulator we use this simulator to test the DSDV and AODV routing protocols In this part the specific models the experiment scenario and the results are described 3 4 1 Physical simulation model In our experiment we assume that the environment nodes detect the environment target in the wide area space where we use a two dimensional model x y plane which is a square space of 1000m x 1000m We use three types of nodes user sensor and environment nodes Moreover ten environment nodes moving randomly in this square space are used different numbers of sensor nodes which are 49 100 225 and 400 fixing in this space The environment nodes which detect the environment target generate data packets sent to the sensor nodes and then the sensor nodes report these packets to the user node In fact the user node which 1s used for collection the 22 IMPLEMENTATION OF NS 2 28 BASED WSN SIMULATOR sensor report is the destination of all data packets The examples of simulation models are shown below 166 67m 1000m Environment node x Sensor node User node Movement direction 166 67m 1000m Y The simulation model of the 49 sensor nodes in 1000m x 1000m Figure 3 7 with
58. ous points that differ between wired and wireless models are the nodes in the network For the wired model the nodes are connected with links to other nodes and fixed 1n the specific position which is different from the wireless model when its nodes move freely and are not connected to other nodes by links These freely moving nodes are called MobileNodes In the NS the C class MobileNode is extended from the parent class Node by adding functions of a wireless and mobile node such as ability to move within a given topology and to receive and transmit signals to and from a wireless channel In this chapter we discuss the structure of MobileNode movement traffic scenario generation for wireless simulations wireless network components routing algorithms trace support and format of wireless traces A1 MobileNode MobileNode is the extension of the Node object which is created by adding functions of movement ability to transmit and receive on a channel to communicate with other MobileNodes The class MobileNode is derived from the class Node The mobility features such as node movement periodic position updates topology boundary etc are implemented in C while creating network components within MobileNode such as Link Layer LL Mac Channel etc have been implemented in OTcl To configure a MobileNode the following OTcl codes are used ns node config adhocRouting val rp V val ll macType val mac V ifqType val
59. pports both wire and wireless networks is implemented to be used with the wireless sensor network This implementation adds the sensor network classes which are environment sensor agent and sensor application classes and modifies the existing classes of wireless network in NS 2 This NS 2 based simulator is used to test routing protocols Destination Sequenced Distance Vector DSDV and Ad Hoc On Demand Distance Vector AODV as one part of simulations Finally the sensor network application models and the extension methods of this NS 2 based simulator for simulations in specific wireless sensor network applications are proposed i 1V Contents 1 INTRODUC TION eed 1 LE cec n LM a a SIM MIA 1 1 27 2 2 BACKGROUND AND RELATED WORK ee eee eeeeesesees ee esses 3 2 1 A SURVEY ON WIRELESS SENSOR NETWORKS 3 2 2 UNS a tee edet o dete a ada 5 RELATE ORE ord tita tete eat 7 3 IMPLEMENTATION OF NS 2 28 BASED WIRELESS SENSOR NETWORK SIMULATOR 9 3 1 BASIC STRUCTURE OF WIRELESS SENSOR 65
60. r TOSSIM Accurate and Scalable Simulation of Entire TinyOS Applications Proceedings of the ACM Conference on Embedded Networked Sensor Systems 2003 18 C Mallanda A Suri V Kunchakarra S S Iyengar R Kannan A Durresi Simulating Wireless Sensor Network with OMNeT Sensor Network Research Group Department of Computer Science Louisiana State Unversity Baton Rouge LA 24 January 2005 19 I Downard Simulating Sensor Networks in NS 2 NRL FR 5522 04 10073 Naval Research Laboratory Washington D C May 2004 20 NRL s Sensor Network Extension to NS 2 Networks and Communication Systems Branch U S Naval Research Lab http pf itd nrl navy mil nrlsensorsim accessed 8 September 2005 21 NS 2 Class Hierarchy http www isi edu nsnam nsdoc classes hierarchy html accessed 25 November 2005 22 The Ns users Archives http mailman isi edu pipermail ns users accessed 25 August 2005 23 F J Ros P M Ruiz Implementing a New Manet Unicast Routing Protocol in NS2 Department of Information and Communications Engineering University of Murcia Spain December 2004 http masimum dif um es nsrt howto html nsrt howto html accessed 14 September 2005 24 Energy Model update in ns 2 http www isi edu ilense software smac ns2 energy html accessed 19 October 2005 38 APPENDIX A BASIC WIRELESS NETWORK MODEL IN NS 2 Appendix A Basic Wireless Network Model in NS 2 The most obvi
61. rammed in C while compound modules which consist of simple modules are programmed in a high level language NED To communicate between modules the exchanging messages which represent the packets in the network are used OMNeT supports users to study the effect of scale node level architecture energy efficiency communication architecture system architecture protocols etc 2 3 2 Simulation of wireless sensor networks In 12 a versatile environment was constructed and three types of nodes sensor target and user nodes were defined for studying sensor networks This study focuses on power consumption and battery lifetime In 19 the NS 2 framework was extended to support for simulating sensor networks PHENOM routing protocol was created to broadcast PHENOM packet from PHENOM node same as target node mentioned in 12 to the sensor node or between the PHENOM nodes This extended framework was used to examine routing protocols in a dynamic sensor network IMPLEMENTATION OF NS 2 28 BASED WSN SIMULATOR 3 Implementation of NS 2 28 based wireless sensor network simulator The network simulator NS 2 supports the simulation of wireless networks but for the simulation of wireless sensor networks it needs to be extended The processes to extend NS 2 28 Network Simulator version 2 28 for wireless sensor network simulations are shown this chapter First the basic structure and the simulation model of wireless sensor networks are ex
62. re available J Sim J Sim formerly known as JavaSim 13 1s an object oriented component based compositional simulation environment written in Java The key benefits of J Sim are that modules can be easily added and deleted in a plug and play manner and it is also useful both for network simulation and emulation by incorporating one or more real sensor devices J Sim provides supporting target sensor and sink nodes sensor channels and wireless communication channels physical media power models and energy models GloMoSim GloMoSim Global Mobile Information system Simulate 14 which is a scalable simulation environment written both in C and Parsec is capable of parallel discrete event simulation GloMoSim is a collection of library modules each of which simulates a specific wireless communication protocol in the protocol stack GloMoSim is widely used to simulate Ad hoc and Mobile wireless networks SENS SENS Sensor Environment and Network Simulator 15 1s a high level sensor network simulator for wireless sensor network applications It consists of application network and physical components which are interchangeable and extensible Application components are used to simulate the execution on a sensor node network components are used to simulate the packet to send and receive functions of a sensor node and physical components are use to model sensors actuators and power and interact with the environment Users can modify
63. rties of critical terrains in a timely manner Data reports from areas of the sensor network will be aperiodic and diverse carrying a range of application specific data WIRELESS SENSOR NETWORK SIMULATOR 2 1 2 Environment applications Examples of environment applications of sensor networks are forest fire detection 2 and flood detection 3 Forest fire detection The sensor network densely deploys a lot of sensor nodes distributed in a wide forest area These nodes are integrated with radio frequency system and may be supplied with power from solar cells which can be used for a long time When the nodes detect the fire they report the data to the central station This application needs the real time communication before the fire spreads and becomes uncontrollable Flood detection An example of the flood detection 1s the ALERT 4 which was developed by the National Weather Service in the 1970s ALERT provides important real time rainfall water level information to evaluate the possibility of potential flooding ALERT sensors are equipped with rainfall water level and weather sensors The detected data are reported via light of sight radio communication from sensor site to the central station 2 1 3 Indoor applications Indoor applications could be home or office applications In this part the home automation 2 and open secure office 5 applications are discussed Home automation The tiny sensor nodes could be attach
64. s Process 2 public 3 Process target 0 4 inline Process amp target return target 5 virtual void get data int amp size char req data 0 6 virtual void process data int size char data 0 7 virtual void send data int size char data 0 8 protected 9 Process target 10 5 Lines5 6 are three public methods provided by the base class process to deal with the user data the method get data 1s used to request data from the previous application in the chain send data is used to send data to the next application in the chain and process data is used to process incoming data 4 2 2 3 Two mechanisms to pass data between applications and transport agents There is no supported Agent class to transmit the user data in the current NS 2 28 but there are two ways to transmit a serialized ADU through the transport agents First for UDP agent we can derive a new agent from UDP class and add a new method send int nbytes char userdata to pass the user data from Application to Agent To pass the data from Agent to Application is tricky because each agent has a pointer to its attached application then it dynamically casts this pointer to an AppConnector and calls AppConnector process data Second for TCP agent where the trickery is more than doing that over UDP because TCP s reassembly queue 15 only 3 WIRELESS SENSOR NETWORK SIMULATOR available for FullTcp But the problem can be solved by abstracting
65. t Sensor Channels Sensor Wireless Channels data Nodes FR Node Y 9 Environment Nodes Figure 3 2 The simulation model of wireless sensor networks The simulation model of wireless sensor networks is generally separated into four main models environment sensor node user node and communication models Environment model This model uses environment nodes to define the physical environment in the simulation For example in the enemy surveillance application this model defines environment nodes moving randomly as enemy moving in the battle field or in the environment temperature detection application this model defines static environment nodes to generate the environment temperature in each area The environment node model architecture 1s shown below 97 Environment Environment Node Application Sensor Stack Sensor Layer Physical Layer DS 22 N Sensor Channel M Figure 3 3 The environment node model architecture The environment node consists of the application layer and the sensor protocol stack sensor and physical layer This node generates a physical data and broadcasts it down to the sensor channel 10 IMPLEMENTATION OF NS 2 28 BASED WSN SIMULATOR Sensor node model This model defines the conditions of sensor nodes such as node mobility communication between nodes routing protocol for r
66. tion can be shown in both text and graphical interface for the events and for the illustration of network topology with the physical environment as background 1 2 Method To achieve the goals of the project the work is divided into four parts studying NS 2 definition the structure of wireless sensor networks implementation of sensor network in the NS 2 environment and extension to simulate in specific applications In the first part we study how NS 2 1s used in programming and create some simple wireless network simulations while in the second part we define the structure of wireless sensor networks and in the third part we implement NS 2 by adding some components to use in the sensor network Finally our simulator is extended to simulate the specific applications BACKGROUND AND RELATED WORK 2 Background and Related Work In this chapter a survey of wireless sensor networks the network simulator NS and the related Work are discussed 2 1 A survey on wireless sensor networks The recent developments in micro electro mechanical system MEMS and wireless communication technology make wireless sensor networks more interested Tiny sensor nodes which are low cost and low power comprise sensing data processing and communicating components A large number of sensor nodes generate the sensor networks Sensor nodes have a self organizing capability to communicate to their neighbor nodes Before they transmit the data to their neig
67. tvar nifs netif mac ifq ll H puts add ENVinterface SENSORchannel is channel n set ns Simulator instance set imepflag ns imep support set t nifs incr nifs this hack prevents MacIndex count from incrementing twice for multi homed sensor node see mac cc Le 19969090 q mac t 1 adjust index j set netif t new iftype set mac t new mactype set ifq t new qtype interface queue set 11 t new lltype link layer set ant t new anttype antenna type set namfp ns get nam traceall H Local Variables H set nullAgent ns set nullAgent set netif netif t set mac mac t set ifq ifq t set 11 SLi 5 H Link Layer H 11 mac mac 50 interface mac layer APPENDIX B IMPLEMENTATION CODES FOR WSN CLASSES 11 down target ifq H Interface Queue ifq target ifq set limit qlen set drpT cmu trace Drop IFQ self ifq drop target drpT if namfp drpT namattach namfp j Mac Layer mac netif netif mac up target 11 netif channel channel netif up target mac netif propagation pmodel Propagation Model netif node self 4 Bind node lt gt interface netif antenna ant t H Physical Channel H channel addif netif if Simulator set MacTrace ON H Trace Received Packets if imepflag set rcvT self mobility trace
68. two parameters which can be configured in the simulation script One is the pulse rate that actually controls how often the environment packet emanates and the other is the environment type Carbon Monoxide heavy seismic activity sound etc 3 3 2 2 Sensor Class This module contains the new sensor agent and sensor application The Agent is defined in ns2 manuals as endpoints where network layer packets are constructed or consumed At least two agents are attached to the sensor node a sensor agent is attached to the sensor channel for consuming the environment packet and a UDP or TCP agent is attached to the wireless channel for constructing packet and sending it down to the sensor application The sensor agent which acts as conduit through which environment packets are received and forwarded to the sensor applications is implemented in the sensoragent h cc The main parts of the sensor agent are 16 IMPLEMENTATION OF NS 2 28 BASED WSN SIMULATOR TCL hook Tcl hook is used to bind our new agent to Tcl to let the sensor agent be instantiated from the Tcl To do this we must inherit from the class TclClass as shown in the following code 1 static class SensorClass public TclClass 2 public 3 SensorClass TelClass Agent SensorAgent 1 dq TclObject create int const char const 5 return new SensorAgent 6 j P class sensor In line 3 the class constructor merely calls the base class with the string Agent sens
69. type of the traffic connection CBR or TCP the number of nodes and maximum number of connections a random seed of CBR connection and a rate which 15 used to compute the interval time between CBR packets A3 Network Component in MobileNodes To setup the network we need to create the network stack to allow channels to access the Mobilenode The network stack consists of a link layer LL ARP Address Resolution Protocol module connected to LL an interface priority queue IFq a MAC layer and a network interface netIF 41 WIRELESS SENSOR NETWORK SIMULATOR The details of each component are presented below Link Layer The important function of the link layer is to set the MAC destination address in the MAC header of the packet The link layer 15 connected to an ARP module to resolve all IPs to hardware MAC address conversions To send packets the routing agent hands down the packets to the link layer which then hands them down to the interface queue To receive the packets the MAC layer sends up the packets to the link layer then the link layer hands them off at the node entry point The class of LL is implemented in ns Il cc h and ns tcl lan ns 1l tcl ARP The ARP module receives queries from the link layer If it knows the destination address it will write the address on the MAC header of the packet Otherwise 1t broadcasts an ARP query and keeps the packet temporarily The ARP has a buffer for a single packet If it se
70. ve many experiences in the simulator Moreover since a sensor network needs to be tailored for a particular application with specific features NS 2 has no such protocols or algorithms support to do that To simulate the wireless sensor networks using the simulators which directly support these sensor networks should be better There are large numbers of directly supportive sensor network simulators as we mentioned in chapter 2 3 SENS whose its modules are programmed in and TOSSIM whose TinyOS codes are used support the high level sensor network simulation But TOSSIM is not sufficient for the low level protocol such as MAC is also one option for the high level sensor network simulation The simple modules of OPNeT are programmed in while its compound modules are programmed in a high level language Although 35 WIRELESS SENSOR NETWORK SIMULATOR J Sim provides supporting target sensor and sink nodes sensor channels and wireless communication channels its use of Java as the simulating language is inevitably sacrificing the efficiency of the simulation As the packet formats energy models and MAC protocols are not representative of those used in wireless sensor networks GloMoSim may not be a good option for the sensor network simulator For SensorSim it is unfortunately no longer developed and 15 not available 5 2 Future Work The extension of this simulator for specific applications such the applications
71. with a limited amount of processing but when coordinated with the information from other nodes they have the ability to measure the given physical environment in great details or to execute a task with complex functions Hence a sensor network can be described as a collection of sensor nodes that coordinate with each other to perform some specific actions Since each sensor node is fitted with an on board processor sensor nodes use their processing abilities to find out simple computations and transmit only the required data These features allow the sensor networks to use in many applications like military security and environment Wireless sensor networks can also be deployed in the ways that the wired sensor system cannot be deployed such as in the chemical environments that are inaccessible by humans Optimizing a wireless sensor network also bring many open issues in the network design Normally analyzing methods computer simulation and physical measurement are the three main techniques used for analyzing the performance of wired and wireless networks However in wireless sensor networks they contain a lot of constrains such as energy limitation decentralized collaboration and fault tolerance These constraints cause many unresolved design and implementation problems so measurements are virtually impossible It appears that simulation 1s currently the primary feasible approach for analysing the behaviours of sensor network and reducing t
72. wo new node types environment and sensor nodes therefore we must add the description details of the new type nodes in this Tcl file In the switch exact routingAgent section the under mentioned codes are added Add ENV set ragent self create env agent node ENVchannel to the environment node configuration sensePower in W to sensor node power discription Add the following functions to generate a new channel and sensor power objects Simulator instproc ENVchannel val self set ENVchannel 1 Simulator instproc ENVmacType val self set ENVmacType val Simulator instproc sensePower val self set sensePower val Add the following functions to attach the agent to the environment node Simulator instproc create env agent node Creating routing agent set ragent new Agent ENV node 1911 self at 0 0 ragent start start BEACON HELLO Messages node set ragent ragent return ragent j Fcl lib ns mobilenode tcl This Tcl script file which defines the wireless network channel description supports the multi channel wireless network In the extension the sensor nodes have at least two interfaces one for the wireless channel and another for the sensor channel The modification implements this kind of multi homed capability in ns mobilenode tcl The modified code of ns mobilenode tcl is shown in Appendix B3 cl lib ns namsupp tcl This tcl file contains nam api t

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