An adaptive mac protocol for wireless sensor networks
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AN ADAPTIVE MAC PROTOCOL FOR WIRELESS SENSOR NETWORKS. Wen-Hwa Liao, Hsiao-Hsien Wang, and Wan-Chi Wu PIMRC ’ 07. Outline. Introduction Related work Asynchronous MAC(AMAC) protocol Simulation Conclusion. Introduction.

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AN ADAPTIVE MAC PROTOCOL FOR WIRELESS SENSOR NETWORKS

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An adaptive mac protocol for wireless sensor networks

AN ADAPTIVE MAC PROTOCOL FOR WIRELESS SENSOR NETWORKS

Wen-Hwa Liao, Hsiao-Hsien Wang, and Wan-Chi Wu

PIMRC’07


Outline

Outline

  • Introduction

  • Related work

  • Asynchronous MAC(AMAC) protocol

  • Simulation

  • Conclusion


Introduction

Introduction

  • In WSNs, the sensors are used to sensing , calculating, and transmitting data.

  • Each sensor equips with battery and works individually.

  • The power of sensor is supplied by battery.


Introduction1

Introduction

  • Because of technical limitations, the power carried by sensor is very limited.

  • To replace battery is very time consuming and costly process.

  • There are a lot of researches on energy saving.

    • Ex:

      • Hardware

      • Operating mechanism


Introduction motivation

Introduction - motivation

  • The sleeping mechanism is one of the most effective energy saving method.

  • In order to conserve energy, the sensor turns its antenna off when it doesn’t have to transmit data.

  • Because the topology of WSNs may change frequently, the saving mechanism should be distributed and self-organized.


Related work smac

Related work - SMAC

  • Each sensor has its fixed wake-up schedule.

  • The sensor exchanges their schedules by broadcasting it to all its immediate neighbors.

Schedule

Sleep

Sleep

Listen

Listen

Time

W. Ye, J. Heidemann, and D. Estrin, “An Energy-Efficient MAC Protocol for Wireless Sensor Networks,” IEEE INFOCOM , 2002.


Related work smac1

Related work - SMAC

B’s schedule

B

A

A

Sleep

Sleep

Listen

Listen

Time

B

Sleep

Sleep

Listen

Listen


Related work pmac

Related work - PMAC

  • Sensor generates sleeping schedule based on its own traffic periodically.

    • Pattern string

      • Bit 1 indicates wake-up

      • Bit 0 means sleep

    • Period

      • N time slots

  • The sensor also exchanges their schedules by broadcasting it to all its immediate neighbors.

  • TDMA system

T. Zheng, S. Radhakrishnan, and V. Sarangan, “PMAC: An Adaptive Energy-Efficient MAC Protocol for Wireless Sensor Networks,” IEEE International Parallel and Distributed Processing Symposium (IDPDS), 2005.


Related work pmac schedule

Related work –PMAC schedule

  • Time is divided into super time frames (STF)

STF

STF

STF

Period i+2

Period i

Period i+1

Time

PRTF

PETF

W

0

1

0

0

1

0

N slots

Exchange the schedule of i+2


Related work pmac1

Related work - PMAC

  • δ is a predefine threshold.

  • The time slot in a period will be repeated, if pattern is small than the size of period N

  • Schedule is composed of sleep-wakeup pattern

    • Ex:

      • 1, 011, 021, 041, ···0m1, 0m01, for m ≤δ

        • 1,01,001,00001 ,δ=4

      • 0δ02 1, 0δ03 1, ···0N−1 1. for δ≤m ≤N

        • 0401,04001 δ=4


Related work pmac2

Pattern:001

m= 2

Pattern:00001

m =4

Pattern:000001

m =5

Update Pattern

PRTF

PETF

0

W

0

0

0

0

1

6 slots

Time

Related work - PMAC

  • δ=4 , N=6

Update Pattern

PRTF

PETF

0

W

0

1

0

0

1

6 slots

Time


Related work pmac3

Related work - PMAC

  • The drawback of PMAC

    • Sensor is necessary to exchange it own schedule for neighbor discovery.

    • PMAC is required to achieve clock synchronous.


Related work quorum based

Related work –quorum based

  • Asynchronous method

r1

r2

c1

c2

Host A

Host B

R. Zheng, J. C. Hou, and L. Sha, “Asynchronous Wakeup for Ad Hoc Networks,”ACM International Symposium on Mobile Ad Hoc Networking & Computing (Mobihoc), 2003.


Amac goal

AMAC –goal

  • Design a hybrid protocol

    • time asynchronous schedule

      • Quorum system

    • traffic-aware schedule

      • PMAC


Amac modify pattern string to adapt to quorum

AMAC -modify pattern string to adapt to quorum

  • Problem with PMAC between quorum

    • The original Pattern is not compatible

    • Ex:

      • Original pattern

      • 001


Amac modify pattern string to adapt to quorum1

AMAC -modify pattern string to adapt to quorum

  • Replace the original sleep-wakeup string bit

  • 1 => 111…1 =>1n

  • 0 => 000…1 =>0n-11


Amac modify pattern string to adapt to quorum2

AMAC - modify pattern string to adapt to quorum

  • Origin PMAC pattern

    • (000..)m-11

  • Exchange to new pattern

    • {(0n-11)(0n-11) (0n-11)}m-1 1n

    • 1N represents selected

      column in quorum

    • The other 0n-11 forms the

      selected row in quorum

n

r

m

c


Amac traffic aware

AMAC –traffic aware

  • Total time slot is also N slots

  • N=n*m

  • Pattern

    • (0n-11) 1n


Amac different size

Pattern

000001 111111

Pattern

000101 000101 111111

AMAC –different size


Simulation

Simulation

  • 100 sensors nodes

  • Duty cycle 100 time slots

  • Execution time 1000~10000 time slot

  • Schedule pattern is re-adjusted after 100 time slots


Simulation1

Simulation


Simulation2

Simulation


Simulation3

Simulation


Simulation4

Simulation


Conclusion

Conclusion

  • AMAC

    • has good adaptation ability

    • doesn’t need time synchronous


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