WEAR: A Balanced, Fault-Tolerant, Energy-Aware

Routing Protocol for Wireless Sensor NetworksKewei Sha, Junzhao Du, and Weisong Shi

Wayne State UniversityInternational Journal of Sensor Netwo

rks 2006

OutlineOutline

IntroductionIntroduction WEAR: A WEAR: A WWeighted eighted EEnergy-nergy-AAware ware RRouting Protocolouting Protocol Hole information calculation Weight definition and calculation

SimulationSimulation ConclusionConclusion

IntroductionIntroduction

Four general requirements of any routing protocol Energy efficient

Find a shortest path Load balanced

Remaining energy Fault tolerant

Bypass the hole Prevent the hole enlarging

Scalable Use localized information

IntroductionIntroduction

source

Destination

GPSR(RHR)GPSR(RHR)

Hole

IntroductionIntroduction

source

Destination

Hole enlargement using GPSRHole enlargement using GPSR

Hole

Motivations and GoalsMotivations and Goals

MotivationsMotivations Identify and maintain the hole information Identify and maintain the hole information Take energy-efficiency, load balance, fault Take energy-efficiency, load balance, fault

tolerance , and scalability into tolerance , and scalability into considerationconsideration

GoalsGoals Extend network lifetimeExtend network lifetime Sensors avoid to route message towards the Sensors avoid to route message towards the

holehole Distribute the load to the alternative pathsDistribute the load to the alternative paths

AssumptionsAssumptions

Sensors have location information Sensors is stationary and the sink is fix

ed Holes in a rectangle shapeHoles in a rectangle shape

WEAR WEAR --- routing modes--- routing modes

Weight contains four factors Distance to the destination Remaining energy of a sensor Local hole information Global location information

WEAR WEAR --- routing modes--- routing modes

Greedy mode Current sensor forwards the message to

the neighbor having the smallest weight value

Bypassing mode The routing follows the right-hand rule

WEAR WEAR --- overview--- overview

Weight of hole

Weight of energy

WEAR WEAR --- Hole information --- Hole information calculationcalculation

To bypass the hole and prevent the To bypass the hole and prevent the hole enlargementhole enlargement Hole identificationHole identification

Hole locatingHole locating Hole announcing Hole announcing Hole propagating Hole propagating

Hole maintenanceHole maintenance

WEAR WEAR --- --- Hole locatingHole locating

Calculate the of the holeCalculate the of the hole Collect the Collect the minimum and maximum x-y coordinminimum and maximum x-y coordin

ators of hole boundaryators of hole boundary and and maximum ID of sensmaximum ID of sensorsors

Use “Locating and bypassing routing holes in sensor networks”

WEAR WEAR --- --- Hole announcing Hole announcing

The hole information is distributed to The hole information is distributed to sensors on the hole boundarysensors on the hole boundary Sensors have complete hole information Sensors have complete hole information

WEAR WEAR --- --- Hole Hole propagatingpropagating

Hole edge sensors broadcast hole Hole edge sensors broadcast hole information to sensors within preset information to sensors within preset maximum hopsmaximum hops

WEAR WEAR --- --- Hole Hole maintenancemaintenance

Hole may enlarge or change shape Holes in a sensor field will change in

two styles Hole enlargement Hole mergence

Hole maintenance Periodical maintenance Reactive maintenance

WEAR WEAR --- --- Hole enlargement Hole enlargement

Failed sensors on the boundary of the hole

Node N is a new stuck node and it starts a hole identification process

WEAR WEAR --- --- Hole mergenceHole mergence

Some sensors located on the edge of the two or more holesNode B recognize a hole mergence

B combines the two hole ID , like ID(h1, h2)

WEAR WEAR ---Weight calculation---Weight calculation

Distance to the destination

Global location information

Local hole information

Remaining energy

,, and

WEAR WEAR --- Weight calculation--- Weight calculation

The Global location information The nearer to the sink, the more important

the sensor In simulation, α= -1

The local hole information In simulation, β= 2

WEAR WEAR --- Weight calculation--- Weight calculation

The remaining energy In simulation, γ= -1

The distance to the destination Geometric distance between the jth sensor and the

destination In simulation = 6

SimulationSimulation

Simulator: Capricorn Communication Range:30m Number of node: 2012 Sensing area: 1000 x 1000 m2

Sink sends a query message Destination sends a reply

message

sink

SimulationSimulation

GPSR

GEARWEAR

EC=Ec/E0

SimulationSimulation

Sensor network lifetime

Network partitions or More than 5% sensors fail

SimulationSimulation

Comparison of the number of failed sensor

SimulationSimulation

Comparison of the path length extension rate

SimulationSimulation

Hole extension

ConclusionConclusion

Proposed a load balanced , fault Proposed a load balanced , fault tolerant ,energy-efficient routing tolerant ,energy-efficient routing protocolprotocol

Extend the lifetime of the sensor Extend the lifetime of the sensor networknetwork

Control the number of the failed Control the number of the failed sensor and hole enlargementsensor and hole enlargement