A Throughput-Adaptive MAC Protocol for Wireless Sensor Networks

Zuo Luo, Liu Danpu, Ma Yan, Wu Huarui

Beijing University of Posts and Telecommunications

Beijing, China

IEEE WiCOM 2010

Outline

• Introduction• System model• TA-MAC• Simulation• Conclusion

Introduction

• All medium access control (MAC) protocols for wireless networks try to make sure that no node should interfere with other nodes

Introduction

• An additional consideration for wireless sensor networks is to manage radio's activity to conserve energy

• While traditional MAC protocols must balance throughput, delay and fairness

Introduction

• Energy consumption on sensor– Collision– Overhearing– Idle listening

Introduction

• In recent research efforts, a duty cycle is used in sensor nodes to reduce energy waste caused by idle listening– S-MAC– T-MAC

Introduction

• S-MAC

active active active activesleep sleep sleep sleep

Time

active active active activesleep sleep sleep sleep

Sensor A

Sensor B

Introduction

• Drawbacks in S-MAC– Energy wasted– Packet dropped

Introduction

• T-MAC

Time

active active active activesleep sleep sleep sleepSensor A

Introduction

• Drawbacks in T-MAC– Packet latency– Packet dropped

Goal

• Propose a new TA-MAC protocol in this paper– Adaptive contention window– BS packet

System model

• Duty cycle and synchronization• Four way handshake• Active period (AP)

BSCSPRCWAP

Contention window

Transmission time of RTS

Transmission time of CTS

Short period between

RTS and CTS

Transmission time of BS

TA-MAC

• Adaptive contention window– Buffer threshold

2

WindowContention

TA-MAC

A

B

C

D

E

FTime

RTS CTS

CTS

RTS

RTS

CTS

A B C D E F

BS

BS

waitingBS

BS

PS

PS

DATA

DATA ACK

ACK

R

C

C

R

D

D A

A

R

C

C

R

D

D A

A

Simulation

• Simulation setup

Parameter Value

Topology 10 Line / 10*10 grid

Active period 20 ms

Frame length 650 ms

Data packet size 100 bytes

Transmitting energy 10 mA

Receiving and idle energy 4 mA

Sleeping energy 20 μA

Simulation result

• Line topology

Simulation result

• Line topology

Simulation result

• Grid topology

Simulation result

• Grid topology

Conclusion

• In this paper the authors proposed two new mechanisms to improve throughput and latency for WSNs

• The simulation results shows that TA-MAC protocol achieves significant trade-off on throughput and energy efficiency

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Thanks for your at tention