Wave Addressing for Wave Addressing for Dense Sensor Dense Sensor

NetworksNetworksSerdar Vural and Eylem EkiciSerdar Vural and Eylem Ekici

Department of Electrical and Computer EngineeringDepartment of Electrical and Computer EngineeringOhio State University, ColumbusOhio State University, Columbus

Proceedings of Second International Workshop on Sensor and ActProceedings of Second International Workshop on Sensor and Actor Network Protocols and Applications (SANPA 2004) or Network Protocols and Applications (SANPA 2004)

jenchijenchi

OutlineOutline

► IntroductionIntroduction►The WADS MechanismThe WADS Mechanism

(Wave Addressing for Dense Sensor (Wave Addressing for Dense Sensor networks)networks)

Wave Source SelectionWave Source Selection Wave Propagation and Region GenerationWave Propagation and Region Generation Address Ambiguity EliminationAddress Ambiguity Elimination

►Performance EvaluationPerformance Evaluation►Conclusion Conclusion

IntroductionIntroduction

►Various techniques have been Various techniques have been proposed to determine the proposed to determine the locationlocation of of sensor nodessensor nodes Using GPSUsing GPS

►Increase the cost of nodesIncrease the cost of nodes►Fast depletion of limited energy sourcesFast depletion of limited energy sources

Signal strength measurementSignal strength measurement►Increased complexity of sensor nodesIncreased complexity of sensor nodes

IntroductionIntroduction

►However, many application can tolerate However, many application can tolerate higher level of uncertainty in location higher level of uncertainty in location informationinformation Intrusion detectionIntrusion detection Interception applicationsInterception applications

► It is not necessary to implement costly, It is not necessary to implement costly, energy-inefficient, and infrastructure-reliant energy-inefficient, and infrastructure-reliant localization schemes that provide high localization schemes that provide high fidelity localizationfidelity localization

IntroductionIntroduction

►Objective of this paperObjective of this paper To introduce To introduce WWaveave A Addressingddressing forfor D Denseense

SSensorensor Networks Networks (WADS)(WADS) method method►To form a coordinate system called To form a coordinate system called WWaveave

MMapping apping CCoordinateoordinate (WMC) (WMC)

Without requiring specialized hardware in Without requiring specialized hardware in sensor nodes or infrastructure support in sensor nodes or infrastructure support in the networkthe network

The WADS mechanismThe WADS mechanism

►System Description and AssumptionsSystem Description and Assumptions To assume that the sensing application To assume that the sensing application

requires requires densely and randomly deployed densely and randomly deployed sensor nodessensor nodes in the sensing field in the sensing field

Sensor nodesSensor nodes►Identical communication capabilitiesIdentical communication capabilities►No mobilityNo mobility►No synchronizationNo synchronization

The WADS mechanismThe WADS mechanism

►WADS operationWADS operation To create the WMC system using the To create the WMC system using the hop hop

distancedistance of sensors from of sensors from two randomly two randomly selectedselected sensor nodes ( sensor nodes (wave sourceswave sources))

Every node in the network receives Every node in the network receives two two wave IDswave IDs

Note that region IDs do not belong to a Note that region IDs do not belong to a single sensor nodes but to single sensor nodes but to a set of sensor a set of sensor nodes in the same localitynodes in the same locality

The WADS mechanismThe WADS mechanism

8 hops 10 hops

The WADS mechanismThe WADS mechanism

►WMC system is accomplished in three WMC system is accomplished in three stepssteps Wave Source SelectionWave Source Selection Wave Propagation and Region GenerationWave Propagation and Region Generation Address Ambiguity EliminationAddress Ambiguity Elimination

Address Ambiguity Address Ambiguity EliminationElimination

C(8,10)

Wave Source SelectionWave Source Selection

► To select the sensor nodes that will serve as To select the sensor nodes that will serve as the two reference points in the networkthe two reference points in the network

► Two possible wave source deployment Two possible wave source deployment scenariosscenarios Pre-deployment selectionPre-deployment selection

►Two wave sources must be placed sufficiently separated Two wave sources must be placed sufficiently separated from each otherfrom each other

Post-deployment selectionPost-deployment selection►Since the sensor network is large, it is easier to use Since the sensor network is large, it is easier to use

simpler distributed algorithms that incurs lower overheadsimpler distributed algorithms that incurs lower overhead

Wave Source Selection Wave Source Selection — Post-deployment selection— Post-deployment selection

► Every sensor generates two numbersEvery sensor generates two numbers A random number (ID)A random number (ID)

►determines if it is a potential candidate for the first or secondetermines if it is a potential candidate for the first or second wave sourced wave source

A random number NA random number Nwaitwait between 0 and N between 0 and Nmaxmax

►NNmaxmax determines the maximum delay tolerance of the system determines the maximum delay tolerance of the system for WMC system generationfor WMC system generation

►Sensor waits for T = TSensor waits for T = Tturnturn X N X Nwaitwait , , where Twhere Tturnturn is the unit time period, which is in the order of the is the unit time period, which is in the order of the

delay of a packet that would travel the maximum diameter odelay of a packet that would travel the maximum diameter of the networkf the network

Wave Source Selection Wave Source Selection — Post-deployment selection— Post-deployment selection

►Once there two numbers are generated, the Once there two numbers are generated, the sensor starts waiting until sensor starts waiting until It receives an ID from another wave source with It receives an ID from another wave source with

the same source ID (1 or 2) the same source ID (1 or 2) Or its timer T expiresOr its timer T expires

► If a sensor receives a wave packet with a If a sensor receives a wave packet with a matching source ID as its own selected ID matching source ID as its own selected ID before its timer expires, it cancels its timerbefore its timer expires, it cancels its timer Otherwise, the sensor generates the first wave Otherwise, the sensor generates the first wave

packetpacket

Wave Source Selection Wave Source Selection — Post-deployment selection— Post-deployment selection

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Wave Source Selection Wave Source Selection — Post-deployment selection— Post-deployment selection

► In case two waves with In case two waves with the same source Ithe same source IDD is present in the network is present in the network

(two sensors selecting (two sensors selecting the same Nthe same Nwaitwait valu valuee), ), ties may be broken by ties may be broken by random numberrandom number in the in the

wave packets inserted by wave sources (Randwave packets inserted by wave sources (Random Source Identifier)om Source Identifier)

Wave Propagation and Region Wave Propagation and Region GenerationGeneration

► Once the wave sources are determined, the sourOnce the wave sources are determined, the sources initiate wave mapping procedure by broadcces initiate wave mapping procedure by broadcasting wave packetsasting wave packets Source ID (SID)Source ID (SID) ：： take a value of 1 or 2take a value of 1 or 2 Distance to Source (DS)Distance to Source (DS) ：： incremented by one every incremented by one every

time the message is broadcasttime the message is broadcast Random Source Identifier (RSI)Random Source Identifier (RSI) ：： a random number a random number

generated by the wave source which is used to break generated by the wave source which is used to break tiesties

► EXEX ：： The wave source WS1 initiates the wave paThe wave source WS1 initiates the wave packet in the format (SID=1, DS=0, RSI)cket in the format (SID=1, DS=0, RSI)

Wave Propagation and Region Wave Propagation and Region GenerationGeneration

► Every sensor nodes SEvery sensor nodes Sii is associated with an is associated with an ID ID pairpair that indicated the region they belo that indicated the region they belong tong to

► Every sensor also keeps track of the random sEvery sensor also keeps track of the random source identifier ource identifier RSIRSI11 and and RSIRSI22 of both wave sou of both wave sourcesrces

)ID,(ID i2

i1

Wave Propagation and Region Wave Propagation and Region GenerationGeneration

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Wave Propagation and Region Wave Propagation and Region GenerationGeneration

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Wave Propagation and Region Wave Propagation and Region GenerationGeneration

► Once a sensor SOnce a sensor Sii obtains an ID pair, it identifies it obtains an ID pair, it identifies itself as belong to a region with the same ID pairself as belong to a region with the same ID pair RRnmnm

►n=IDn=ID11 and m=ID and m=ID22

► Note that not all nodes in the same region are wiNote that not all nodes in the same region are within each other’s direct communication rangethin each other’s direct communication range To assume that all nodes of a region form a connecteTo assume that all nodes of a region form a connecte

d subgraphd subgraph

Address Ambiguity Address Ambiguity EliminationElimination

C(8,10)

Address Ambiguity Address Ambiguity EliminationElimination

► The first stepThe first step To To designate a sensor DSdesignate a sensor DSnmnm as the representative of a as the representative of a

region Rregion Rnmnm►To select the sensor node that has To select the sensor node that has the highest number of neithe highest number of nei

ghbors of the same ID paironghbors of the same ID pairon

Once selected, each DSOnce selected, each DSnmnm generates generates a random designa random designated sensor identifier (RDSIated sensor identifier (RDSInmnm)) to uniquely identify its to uniquely identify its regionregion

To use RDSIs to associate neighboring regions with cTo use RDSIs to associate neighboring regions with correlated codesorrelated codes

Address Ambiguity Address Ambiguity EliminationElimination

►The second stepThe second step To identify the regions that lie on the line To identify the regions that lie on the line

that connects two wave sources => that connects two wave sources => border regionsborder regions

Address Ambiguity Address Ambiguity EliminationElimination

Address Ambiguity Address Ambiguity EliminationElimination

►The third stepThe third step To disseminate identifying codes to both sides of the To disseminate identifying codes to both sides of the

bordersborders Partition identifiers (PIDs) are generated by messages Partition identifiers (PIDs) are generated by messages

sent by both wave sourcessent by both wave sources Each region will have a four bit PIDEach region will have a four bit PID

Address Ambiguity Address Ambiguity EliminationElimination

PID=1010

PID=1000

Performance evaluationPerformance evaluation

►A set of experiments on random A set of experiments on random sensor network topologiessensor network topologies

There are 4X2X2=16 different scenariosThere are 4X2X2=16 different scenarios►For each scenario, 100 independent random For each scenario, 100 independent random

networks have been generatednetworks have been generated

Square Field

750 Nodes/Km2 1000 Nodes/Km2

1500 Nodes/Km2 2000 Nodes/Km2

Corridor Field

750 Nodes/Km2 1000 Nodes/Km2

1500 Nodes/Km2 2000 Nodes/Km2

► Example wave mapping coordinate systems for Example wave mapping coordinate systems for close wave sourcesclose wave sources

Conclusions Conclusions

►The WADS create a virtual coordinate The WADS create a virtual coordinate system in dense sensor networkssystem in dense sensor networks

►Do not require GPS device or signal Do not require GPS device or signal processing capabilities in the sensor processing capabilities in the sensor nodesnodes

►No infrastructure support such as special No infrastructure support such as special location beacons are necessarylocation beacons are necessary

►The WADS utilizes two randomly selected The WADS utilizes two randomly selected nodes to form the WMC systemnodes to form the WMC system