CMAC: AN ENERGY EFFICIENT MAC LAYER PROTOCOL USING CONVERGENT PACKET FORWARDING FOR WIRELESS SEN-SOR NETWORKS

SECON 2007

SHA LIU, KAI-WEI FAN, PRASUN SINHA

DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING, OHIO STATE UNIVERSITY

# 172008-11-11

Presentation: Jinhyung LeeComputer Network Lab

CONTENTS INTRODUCTION

CONTRIBUTION

FEATURES

EVALUATION

CONCLUSION

DISCUSSION

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INTRODUCTION MAC LAYER DESIGN GOALS FOR WSN

LONG LIFETIME LOW LATENCY LOW MAINTENANCE OVERHEAD HIGH THROUGHPUT

EXISTING SOLUTIONS SYNCHRONIZED MAC

SMAC, TMAC, DMAC CONSUME A LOT OF ENERGY ON PERIODIC SYNCHRONIZATION

UNSYNCHRONIZED MAC BMAC, XMAC USE LONG PREAMBLES

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CONTRIBUTION CMAC

UNSYNCHRONIZED DUTY CYCLING NO SYNCHRONIZATION OVERHEAD

AGGRESSIVE RTS, ANYCAST QUICKLY MAKE ROUTING PROGRESS

CONVERGENT PACKET FORWARDING

AVOID OVERHEAD OF ANYCAST

ACHIEVED GOALS ENERGY EFFICIENCY LOW LATENCY HIGH THROUGHPUT

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CONVERGENT MAC

AGGRESSIVE RTS

ANYCAST PACKET FORWARDING

CONVERGENT FORWARDING

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CONVERGENT MAC

AGGRESSIVE RTS

ANYCAST PACKET FORWARDING

CONVERGENT FORWARDING

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AGGRESSIVE RTS LONG PREAMBLE MECHANISM OF BMAC

HIGH LATENCY

BREAKS UP LONG PREAMBLE INTO MULTIPLE RTS PACKETS RTS BURST SENDER RECEIVES A CTS, IT SENDS PACKET IMMEDIATELY LATENCY AT EACH HOP COULD BE REDUCED BY HALF

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Sender

Receiver

Sleep

Sleep

Packet

PacketSleep

Sleep

Sleep

Sleep

Sleep

SleepRTS RTS RTS

RX CTS

RX Sleep

Aggressive RTS

AGGRESSIVE RTS ASSESS CHANNEL QUICKLY DURING EACH WAKE

UP TIME TO ALLOW NODES TO WORK AT A VERY LOW DUTY CYCLE IF RECEIVER WAKES UP DURING THE GAP BETWEEN TWO

RTSS MISS RTS BURST

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RTS RTS

Channel check

AGGRESSIVE RTS DOUBLE CHANNEL CHECK

CHECK THE CHANNEL TWICE TO AVOID MISSING ACTIVI-TIES

FOR EACH CHANNEL CHECK, NODES SAMPLE UP TO 5 TIMES

BETWEEN TWO CHANNEL CHECKS, PUT TO SLEEP MODE INTERVAL MUST BE SHORTER THAN RTS TRANSMISSION

TIME

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RTS RTS

Channel check

RTS RTS

Channel check

RTS RTS

Channel check

(a) (b)

(c)

Executed channel check

Canceled channel check

CONVERGENT MAC

AGGRESSIVE RTS

ANYCAST PACKET FORWARDING

CONVERGENT FORWARDING

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ANYCAST PACKET FORWARDING

NODES OTHER THAN TARGET RECEIVER MAY WAKE UP EARLIER CAN MAKE SOME PROGRESS TOWARD SINK REDUCE LATENCY

ANYCAST TO THE ONE CLOSEST TO DESTINATION FORWARDING SET

NEIGHBOR NODES OF THE SENDER THAT ARE CLOSER TO THE DESTINATION

PARTITION INTO 3 SUB REGIONS

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ANYCAST PACKET FORWARDING

MORE THAN ONE NODE MAY CONTEND TO SEND CTS

EACH GAP BETWEEN TWO CONSECUTIVE RTS IS DIVIDED 3 CTS SLOTS FOR (R1, R2, R3) PRIORITIZE THE CTS PACKET TRANSMISSION EACH CTS SLOT DIVIDED INTO MINI-SLOTS EACH NODE IN THE SAME REGION RANDOMLY PICKS UP A

MINI-SLOT

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Canceled RTS

CTS

RTSSender

CTS slot

Canceled CTS

mini-slot

Node in R1

Node in R1

Node in R2

Node in R3

Canceled CTS

Canceled CTS

CONVERGENT MAC

AGGRESSIVE RTS

ANYCAST PACKET FORWARDING

CONVERGENT FORWARDING

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CONVERGENT FORWARDING ANYCAST HAS HIGHER OVERHEAD THAN UNICAST

SUBOPTIMAL ROUTES ANYCAST RTS/CTS

SWITCH FROM ANYCAST TO UNICAST IF NODE IS ABLE TO COMMUNICATE WITH A NODE IN R1 CANNOT FIND A BETTER NEXT HOP THAN CURRENT ONE

NODES STAY AWAKE FOR A SHORT DURATION AFTER RECEIVING A PACKET

SYNCHRONIZED WAKE-UP SCHEDULING TIMEOUT

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CONVERGENT FORWARDING

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EXPERIMENTS TESTBED : KANSEI TESTBED

105 XSM NODES 7 X 15 TOPOLOGY, SEPARATION OF 3 FEET

IMPLEMENTATION PARAMETERS

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CTS-slot length 7.488 ms

Number of CTS-slots 3

Mini-slot length 416 μs

Number of mini-slots 6

RTS packet size 44 bytes

Double channel check interval 10 ms

EXPERIMENTS METRICS

THROUGHPUT LATENCY NORMALIZED ENERGY CONSUMPTION

SCENARIOS STATIC EVENT MOVING EVENT

COMPARISON CMAC 1%, BMAC 1% CMAC 100%, BMAC 100%

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EXPERIMENTS – STATIC SCENARIO

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ThroughputLatencyEnergy Con-sumption

EXPERIMENTS - MOVING SCENARIO

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ThroughputLatencyEnergy Con-sumption

SIMULATION

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ThroughputLatencyEnergy Con-sumption

CONCLUSION CMAC

AGGRESSIVE RTS, ANYCAST, CONVERGENT PACKET FOR-WARDING

SUPPORTS HIGH THROUGHPUT, LOW LATENCY AND CON-SUMES LESS ENERGY THAN EXISTING SOLUTIONS

DISCUSSION NO CONSIDERATION OF NODE MOBILITY AWAKE DURATION AFTER RECEIVING PACKET IS SENSI-

TIVE TO PERFORMANCE FOR LOW DATA RATES, CAN’T CONVERGE FROM ANYCAST

TO UNICAST TOO SIMILAR WITH XMAC

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Thank You

# 17CS 710 2008-11-11

Appendix

# 17CS 710 2008-11-11

HOW LONG SHOULD NODES KEEP AWAKE AF-TER RECEIVING A PACKET?

LONGER AWAKE PERIOD →LOWER LATENCY BUT LONGER AWAKE PERIOD MAY NOT BE

MORE ENERGY EFFICIENT DEPENDENT ON DATA RATE AND NODE DENSITY

lambda: packet arrival rate in a Poisson arrival process

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PERFORMANCE OF ANYCAST IF LACK OF CONVER-GENCE

EXPERIMENT SETTINGS: VARY TRANSMISSION RANGES TO CREATE DIFFERENT NODE

DENSITIES METRIC:

LATENCY NORMALIZED BY DISTANCE (HOPS IN UNICAST) RESULTS:

CMAC 1% ACHIEVES LOWER LATENCY THAN BMAC 1%