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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

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
conclusion
Conclusion
  • AMAC
    • has good adaptation ability
    • doesn’t need time synchronous