An Energy-Efficient An Energy-Efficient Geographic Routing with Geographic Routing with

Location Errors in Wireless Location Errors in Wireless Sensor NetworksSensor Networks

Julien Champ and Clement SaadJulien Champ and Clement Saad

I-SPAN 2008, SydneyI-SPAN 2008, Sydney(The international Symposium on Parallel Architectures, Algorithms, and Networks)(The international Symposium on Parallel Architectures, Algorithms, and Networks)

OutlineOutline

► IntroductionIntroduction►Definition of Metric for Arc CostDefinition of Metric for Arc Cost►The Routing AlgorithmThe Routing Algorithm►SimulationsSimulations►ConclusionConclusion

IntroductionIntroduction

► Wireless Sensor NetworkWireless Sensor Network Random DeploymentRandom Deployment Inaccurate location informationInaccurate location information Energy ConstraintEnergy Constraint Reply data with multi-hop routing pathReply data with multi-hop routing path

► Routing algorithmRouting algorithm Flooding is not suitable in large Wireless Sensor NetworksFlooding is not suitable in large Wireless Sensor Networks GPS wastes heavy costGPS wastes heavy cost

► A routing algorithm has to select paths toward the A routing algorithm has to select paths toward the destination that consume as less energy as destination that consume as less energy as possible.possible.

IntroductionIntroduction

►Sensors are staticSensors are static►HelicopterHelicopter

(Xa, Ya)

Sensora

Sensorb

Sensorc (Xc, Yc)

(Xb, Yb)

εa

εa : position error bound

εa

velocity

IntroductionIntroduction

►G G = (V, E)= (V, E)►

IntroductionIntroduction

►MotivationsMotivations Communication Probability with Location Communication Probability with Location

ErrorsErrors Energy SavingEnergy Saving

►GoalGoal Metric for Arc CostMetric for Arc Cost Using this metric to instead of location Using this metric to instead of location

information in each sensor nodeinformation in each sensor node

OverviewOverview

►Only one destination, sink nodeOnly one destination, sink node►Sensor with no location informationSensor with no location information►Sensor with metric is determined by Sensor with metric is determined by

the computer on the helicopterthe computer on the helicopter►Sensor find route to the destination by Sensor find route to the destination by

the proposed distributed algorithmthe proposed distributed algorithm

Definition of Metric for Arc Definition of Metric for Arc CostCost

►A cost to each arc of the graphA cost to each arc of the graph The probability of communicationThe probability of communication Energy consumptionEnergy consumption The realized progressThe realized progress

cost

cost

cost

cost

cost

The probability of The probability of communicationcommunication

►Three casesThree cases Two sensors are located with exact Two sensors are located with exact

positionspositions Only one sensor is located with estimated Only one sensor is located with estimated

position and the other node is exactly position and the other node is exactly locatedlocated

Two sensors are located with estimated Two sensors are located with estimated positionspositions

The probability of The probability of communication communication

►ppABAB: a function to estimate the communica: a function to estimate the communication probability between A and Btion probability between A and B

►Case1Case1

►Case2Case2

The probability of The probability of communicationcommunication

►Case3Case3

guarantee

possible to communicateor possible not

Definitely impossible

The probability of The probability of communicationcommunication

►Case3Case3

ppABAB =[0,1] =[0,1]

The ration between energy The ration between energy consumption and realized consumption and realized

progressprogress►RRABAB :normalized value between 0 and 1 :normalized value between 0 and 1

as a function of energy consumption as a function of energy consumption and progress realized when sensor and progress realized when sensor AA sends a message to sends a message to BB

The ration between energy The ration between energy consumption and realized consumption and realized

progressprogress►[8], 1998 ICC [8], 1998 ICC

►As authors in [8]As authors in [8] aa = 4, = 4, cc = 2 x 10 = 2 x 1088

The ration between energy The ration between energy consumption and realized consumption and realized

progressprogress►Energy / DistanceEnergy / Distance

►Optimal transmission rangeOptimal transmission range

The ration between energy The ration between energy consumption and realized consumption and realized

progressprogress►EE’(’(dd)) = 0 = 0

►Use this optimal transmission range in ordUse this optimal transmission range in order to normalize ratio er to normalize ratio RR between 0 and 1 between 0 and 1

The ration between energy The ration between energy consumption and realized consumption and realized

progressprogress► The optimal ratioThe optimal ratio

► The ratio corresponding The ratio corresponding to (to (AA, , B B ))

dA,BS

dB,BS

dAB

A

B

BS

The ration between energy The ration between energy consumption and realized consumption and realized

progressprogress►RRABAB

Metric for Arc CostMetric for Arc Cost

►Cost to Arc (Cost to Arc (AA, , BB))

The Routing AlgorithmThe Routing Algorithm

►Energy-Efficient Geographic Routing (EEG-Energy-Efficient Geographic Routing (EEG-Routing)Routing)

►The least path costThe least path cost to reach the base stati to reach the base station for its possible neighbors, computer coon for its possible neighbors, computer computes before deployment.mputes before deployment.

►Each sensor stores a Table Each sensor stores a Table Tab_CostsTab_Costs ass associating to each neighbor the cost to reacociating to each neighbor the cost to reach destinationh destination

►Exchange Hello messageExchange Hello message

The Routing AlgorithmThe Routing Algorithm

►The position of the sensor which The position of the sensor which detected an eventdetected an event

►A message A message idid►Detected event informationDetected event information

The Routing AlgorithmThe Routing Algorithm

C

B: CAB

C: CAC

CAC>CABC: CAC A: CBC

A: CCB

D: CCD

D

B

A

C: CDC

Base Station

SimulationsSimulations

►100 sensors100 sensors►1200 x 1200 area1200 x 1200 area►Adjusting the maximum transmission Adjusting the maximum transmission

range to have densities between 6 and range to have densities between 6 and 20.20.

SimulationsSimulations

SimulationsSimulations

ConclusionConclusion

►A new geographic routing for WSN A new geographic routing for WSN based on estimated positions with based on estimated positions with position error bounds.position error bounds.

►EEG-Routing sends message along EEG-Routing sends message along paths having the best trade-off paths having the best trade-off between communication probability, between communication probability, progress and energy consumptionprogress and energy consumption

Thank You !Thank You !