O-MAC: A Receiver Centric Power Management Protocol

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O-MAC A Receiver CentricPower Management
Protocol

• Hui Cao, Kenneth W. Parker, Anish Arora

The Ohio State University, The Samraksh Company
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Outline
1. Receiver centric design 2. Energy efficiency
comparison 3. O-MAC protocol design
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Part I Receiver Centric Design
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Dominant Receiver Power Consumption
One typical surveillance application
Receiver Radio 2100 J/day
Signal processing 60 J/day
Everything else 8 J/day

• Large portion of energy is consumed in receiver
  radio

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Increasing Rx Power Consumption
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Receiver Centric vs. Transmitter Centric

• Transmitter Centric MAC design
• Transmitter implicitly knows receiver will wakeup
  during transmission
• Collision avoidance is transmitter driven (i.e.,
  RTS-CTS, CCA)
• Receiver Centric MAC design
• Receiver explicitly communicates its wakeup
  schedule to transmitter
• Collision avoidance is receiver driven (i.e.,
  receivers use TDMA)

Transmitter
Receiver
Transmitter
Receiver
Transmitter
Receiver
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Why Receiver Centric Design?

• Historically, MAC design has focused on
  Transmitter Efficiency
• However, dominant cost of receiver radio has
  implied that

Goodput
Receiver Efficiency
Receiver Power Consumption
Goodput
Transmitter Efficiency
Transmitter Power Consumption
Goodput
Total Energy Efficiency
Transmitter Receiver Power Consumption

• We claim Receiver Centric approach yields
  substantially higher Receiver Efficiency

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Part II Energy Efficiency Comparison
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Assumptions and Notations

• Traffic model
• Uniform random traffic
• Notations
• E energy efficiency

Goodput (Msgs Sent Receive)
Total (Msgs Sent Receive)
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Theoretical Energy Efficiency

• Well consider
• Synchronous Blinking (S-MAC, T-MAC)
• Long Preamble (B-MAC, WiseMAC)
• Asynchronous Wake-up
• Random Time-Spreading
• Staggered On
• Pseudo-random Staggered On

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Synchronous Blinking (e.g. S-MAC T-MAC)
? number of interfering nodes
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2) Long Preamble (e.g. B-MAC, WiseMAC)
? duty cycle
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3) Asynchronous Wakeup
? duty cycle
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4) Random Time Spreading

• In each time slot, each node wakes up randomly
• No time sync
• Power efficiency

? number of interfering nodes
? duty cycle
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5) Staggered On

• Only one receiver wakes up in the interference
  region at one time
• Scheduled globally to avoid receiver collision

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6) Pseudo-random Staggered On
r is a factor near 1
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Energy efficiency comparison
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Part III O-MAC Protocol Design
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O-MAC Protocol Design

• Based on Pseudo-random Staggered On

• The Core Protocol
• Interfaces
• Neighbor list
• Send
• Receive
• Synchronous ACK
• Pseudo-random Scheduler

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O-MAC Analysis and Simulation

• Simulation confirms theoretical analysis
• Maximal energy efficiency for particular traffic
  load!
• ?Adaptive duty cycle

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O-MAC Key Implementation Issues

• Time Synchronization
• Current technique
• lt 10 PPM
• Every 2 minutes, to guarantee 1ms accuracy
• Cost 0.001 duty cycle

Sender Centric Application
Receiver Centric Communication

• Adaptive Duty Cycle
• A cross layer design issue

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Conclusion and Future work

• Conclusion
• Receiver Centric has substantial impact on power
  management
• Receiver vs. Transmitter Collision Avoidance
• OMAC has been implemented and is being integrated
  for mobile sensor network experiments on Dec.7 at
  OSU

• Future work
• Receiver Centric higher layer protocol
• (Network, Transport, Application)
• Adaptive duty cycle scheme