Variable Bandwidth Allocation Scheme for Energy Efficient Wireless Sensor Network

SeongHwan Cho, Kee-Eung KimKorea Advanced Institute of Science and Technology (KAIST),

Samsung Advanced Institute of Technology

ICC 2005ICC 2005

SpeakerSpeaker：： Shih-Yun, HsuShih-Yun, Hsu

OutlineOutlineIntroductionGoalAssumptionEnergy consumption vs BandwidthVariable Bandwidth Allocation (VBA)Bandwidth Allocation AlgorithmSimulation ResultsConclusions

IntroductionIntroductionThe characteristics of the sensor network

Small packets (hundreds of bits)Short transmission range (< 10m)Low mobilityYears of lifetime with small energy resourceDistributed redundantly

Cluster

IntroductionIntroductionAn Application-Specific Protocol Architecture

for Wireless Microsensor NetworksIEEE Trans. on wireless communications, 2002

TDMA scheme with DSSS in a clusterAvoiding inter-cluster interference

AdvantageEnergy efficient

Disadvantage Increases the packet sizeAggravates time synchronization problems

IntroductionIntroduction[5][6][7] are aimed at a general sensor network

with multi-hop routingDo not consider

Bandwidth utilization to minimize energy consumption

GoalGoalProposes a mechanism

ClusteringVariable bandwidth allocationTime-frequency slot assignment

AssumptionAssumption There are many frequency bands available The network environment bases on cluster structure

Energy consumption vs BandwidEnergy consumption vs Bandwidthth6 sensors100 bits packet100 bpsUsing hybrid FDM-TDM methodFrame time = 10ms

Energy consumption vs BandwidEnergy consumption vs Bandwidthth

Energy consumption vs BandwidEnergy consumption vs Bandwidthth

RE： event rate

Nsync： the number of synchronizations per second

ρ： the error in the reference crystal oscillator

,

,

,

total tx rx sync

E tx sync rx sync

E tx rx syncguard

P P P

R E N E

R E ET

Energy consumption vs BandwidEnergy consumption vs Bandwidthth

,

max

total E tx rx sync

tx

P R E EM

TNR

M： the number of channels available N： the total number of sensors Rmax： the maximum event rate of the sensors

Energy consumption vs BandwidEnergy consumption vs Bandwidthth

Energy consumption vs BandwidEnergy consumption vs Bandwidthth

Variable Bandwidth Allocation (VBA)Constant bandwidth allocation (CBA)

Allocates equal amount of frequency bands to the clusters regardless of its node density

Variable Bandwidth Allocation (VBA)

Variable Bandwidth Allocation (VBA)

Variable Bandwidth Allocation (VBA)

Bandwidth

Time

Variable Bandwidth Allocation (VBA)

1 1

min ( )

Cluster iN n

network ii k

P P k

,( )( , )

i E tx rx sync

guard

P k R E ET i k

,

( , ) ( , )

j i

guard jj C C

T i k dist k A

Bandwidth Allocation AlgorithmSingle macrocluster slot assignmentPairwise joint macrocluster slot assignmentGlobal network slot allocation

Bandwidth Allocation Algorithm Single macrocluster slot assignment

Bandwidth Allocation Algorithm Pairwise joint macrocluster slot assignment

Bandwidth Allocation Algorithm

A B C

Θ1 Θ2

Bandwidth Allocation Algorithm

A B C

Θ1 Θ2

Θj= Θ2 , nj=3Θi= Θ1 , ni=2

ni < nj

BTframe

Bandwidth Allocation Algorithm

A B C

Θ1 Θ2

Θj= Θ1 , nj=2Θi= Θ2 , ni=3

ni > nj

Tframe B

Bandwidth Allocation Algorithm Global network slot allocation

Bandwidth Allocation Algorithm

Simulation ResultsSimulation Results25 clusters and 750 sensor nodesAveraging 100 different simulations for each

standard deviation

Simulation ResultsSimulation Results

Simulation ResultsSimulation Results

ConclusionsConclusionsA variable fine-grain bandwidth allocation sch

eme is proposed for a collaborative sensor network with multiple clusters

This scheme reduces the power consumption of the network by exploiting the fact that power consumption from synchronization can be reduced if more bandwidth is available

Thank You!!Thank You!!