Low Power MAC for Ad Hoc Wireless Network EECS University of California at Berkeley
Outline <ul><li>Media Access and Existing Solutions </li></ul><ul><li>MAC for PicoNode Overview </li></ul><ul><li>Multi-Ch...
Wireless Media Access Control <ul><li>MAC:  Let multiple radios share the  same communication media. </li></ul>Physical MA...
Media Access in Multi-hop Networks <ul><li>Large number of short range radios in a wide area  Transmission Locality </li><...
Solution 1: Contention Based <ul><li>MACA :   [p. Kam, 90] </li></ul><ul><ul><li>RTS-CTS-DATA </li></ul></ul><ul><li>MACAW...
Solution 2: UCLA Allocation Based <ul><li>Localized Central Control: Cluster </li></ul><ul><li>Self-elected Cluster Head. ...
PicoMAC ? Why Not Just Pick One? <ul><li>Most existing MACs are Targeted for  </li></ul><ul><ul><li>One-hop, centralized c...
Opportunities for PicoMAC <ul><li>Application Driven,  Low Duty-Cycle MAC </li></ul><ul><li>New Radio Architectures </li><...
Outline <ul><li>Media Access and Existing Solutions </li></ul><ul><li>MAC for PicoNode Overview </li></ul><ul><li>Multi-Ch...
P ico N ode  ≠  M ulti M edia <ul><li>Low-date Rate Radio :  10kbps (peak) </li></ul><ul><li>Low Traffic Duty Cycle:  </li...
Design Goal <ul><li>Primary Goal: energy / useful bit  (EPB) </li></ul><ul><li>Scalability :  both in global sense of netw...
Where Energy Goes? <ul><ul><li>When idle: Channel Monitoring </li></ul></ul><ul><ul><li>Collision and Retransmission  </li...
Low Power MAC for PicoNode <ul><li>Spread Spectrum Multi-Channel Scheme </li></ul><ul><ul><li>To Reduce Collision Rate </l...
Outline <ul><li>Media Access and Existing Solutions </li></ul><ul><li>MAC for PicoNode Overview </li></ul><ul><li>Multi-Ch...
CDMA Multi-Channel Scheme <ul><li>Parallel Transmission without Synch. </li></ul><ul><li>Implicit Local Address: Channel  ...
Multiple Channel Assignment <ul><li>Sender based CA </li></ul><ul><li>No primary collision </li></ul><ul><li>Receiver need...
Find the Solution: Graph Coloring <ul><li>Goal:  For any node, all its neighbors are with different colors </li></ul><ul><...
Performance Analysis <ul><li>Model : a  ∆ -regular graph </li></ul><ul><li>p : traffic density </li></ul>SC (Share Single ...
CA Performance Analysis SC TCA RCA SC TCA RCA
Outline <ul><li>Media Access and Existing Solutions </li></ul><ul><li>MAC for PicoNode Overview </li></ul><ul><li>Multi-Ch...
Power Down Data Radio <ul><li>Current Radio Sleeping Mode: 10~50% Power Consumption </li></ul><ul><li>For PicoNode Running...
Sleeping mode signaling <ul><li>Problem : How To Send Data To a Sleeping Node? </li></ul><ul><li>Solution: </li></ul><ul><...
Wake-up Radio <ul><li>Always running </li></ul><ul><ul><li>Super low power: 10 -4 ~ 10 -3  active mode power </li></ul></u...
Wakeup Sequence and Energy Profile <ul><li>E (useful data traffic) +  E (overhead traffic) +  E (idle) </li></ul>Node B DA...
EPB Performance Analysis L p  = 20bits L p  = 60bits L p  = 300bits Radio Bit Rate R=10kbps Number of Channels M = 32 Netw...
EPB Performance Analysis P s  = 1uW P s  = 100uW P s  = 1mW Conclusion: For duty cycle 1~10 percent: 10 ~ 100  times better
Outline <ul><li>Media Access and Existing Solutions </li></ul><ul><li>MAC for PicoNode Overview </li></ul><ul><li>Multi-Ch...
Things To Be Addressed <ul><li>Topology Control </li></ul><ul><li>Equal Transmission Power, Results in Bad Connectivity </...
Design Flow & Environment Algorithm Exploration/Evaluation System Simulation Performance Evaluation SDL Functional Verific...
Conclusion <ul><li>Create General-Purpose Tools and Vertical Design Methodology for Application Driven Low Power Protocol ...
Q & A Thanks !
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BWRC Chunlong Guo, Prof. Jan Rabaey

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  • Adaptivity need refined
  • Mobility Aware: Energy Aware: Traffic Aware:
  • BWRC Chunlong Guo, Prof. Jan Rabaey

    1. 1. Low Power MAC for Ad Hoc Wireless Network EECS University of California at Berkeley
    2. 2. Outline <ul><li>Media Access and Existing Solutions </li></ul><ul><li>MAC for PicoNode Overview </li></ul><ul><li>Multi-Channel MAC and Distributed Algorithm </li></ul><ul><li>Sleeping Mode Based on Ultra Low Power Wakeup Radio </li></ul><ul><li>Future Research, Design Methodology and Environment, Status and Time Line </li></ul>
    3. 3. Wireless Media Access Control <ul><li>MAC: Let multiple radios share the same communication media. </li></ul>Physical MAC Network Application <ul><li>Local Topology Discovery and Management. </li></ul><ul><li>Media Partition By Allocation or Contention. </li></ul><ul><li>Provide Logical Channels to Upper Layers. </li></ul>Time Code Frequency
    4. 4. Media Access in Multi-hop Networks <ul><li>Large number of short range radios in a wide area Transmission Locality </li></ul>Problems : Good thing: Channel Reuse Hidden Terminal, ( CSMA is not appropriate) No Global Synch. A B C E D
    5. 5. Solution 1: Contention Based <ul><li>MACA : [p. Kam, 90] </li></ul><ul><ul><li>RTS-CTS-DATA </li></ul></ul><ul><li>MACAW: [V. Bharghavan, 1994] </li></ul><ul><ul><li>add link layer ACK . </li></ul></ul><ul><li>FAMA [C.L. Fuller, 95] 802.11: </li></ul><ul><ul><li>Add carrier sensing </li></ul></ul><ul><ul><li>Optional ACK </li></ul></ul><ul><li>PAMAS: [S. Singh, 2000] </li></ul><ul><ul><li>Power aware MAC </li></ul></ul><ul><ul><li>Separate signaling channel </li></ul></ul>RTS CTS RTS Collision at B <ul><li>Collision still exists. </li></ul><ul><li>Too much overhead. </li></ul>A B C D collide
    6. 6. Solution 2: UCLA Allocation Based <ul><li>Localized Central Control: Cluster </li></ul><ul><li>Self-elected Cluster Head. </li></ul><ul><li>Neighboring Clusters Use Different Codes </li></ul><ul><li>Same Code, TDMA Inside Cluster </li></ul><ul><li>Virtual Circuit: QoS Support </li></ul>Unstable Cluster Structure Too much Management Overhead
    7. 7. PicoMAC ? Why Not Just Pick One? <ul><li>Most existing MACs are Targeted for </li></ul><ul><ul><li>One-hop, centralized control network: cellular network, 802.11, Bluetooth… </li></ul></ul><ul><ul><li>Bandwidth hungry application, strict QoS requirement. </li></ul></ul><ul><li>Existing MACs are Based on Existing Radio’s </li></ul><ul><ul><li>More than 90% of power is burned when radio is idle. </li></ul></ul>‘ Low power’ System Built on Existing MAC is NOT Low Power
    8. 8. Opportunities for PicoMAC <ul><li>Application Driven, Low Duty-Cycle MAC </li></ul><ul><li>New Radio Architectures </li></ul><ul><li>Vertically-Integrated Interactive Design Methodology </li></ul>PHY MAC Application Network
    9. 9. Outline <ul><li>Media Access and Existing Solutions </li></ul><ul><li>MAC for PicoNode Overview </li></ul><ul><li>Multi-Channel MAC and Distributed Algorithm </li></ul><ul><li>Sleeping Mode Based on Ultra Low Power Wakeup Radio </li></ul><ul><li>Future Research, Design Methodology and Environment, Status and Time Line </li></ul>
    10. 10. P ico N ode ≠ M ulti M edia <ul><li>Low-date Rate Radio : 10kbps (peak) </li></ul><ul><li>Low Traffic Duty Cycle: </li></ul><ul><ul><li>~ 1%, 1~200 Bytes/source/s </li></ul></ul><ul><li>Short Packet: <50Bytes </li></ul><ul><li>Loose QoS Requirements, Often not Delay Sensitive </li></ul>
    11. 11. Design Goal <ul><li>Primary Goal: energy / useful bit (EPB) </li></ul><ul><li>Scalability : both in global sense of network size and local sense of nodes density </li></ul><ul><li>Distributed Protocol : to achieve a robust and self-configuring network. </li></ul><ul><li>Mobility : limited number of mobile nodes, with limited speed. </li></ul>
    12. 12. Where Energy Goes? <ul><ul><li>When idle: Channel Monitoring </li></ul></ul><ul><ul><li>Collision and Retransmission </li></ul></ul><ul><ul><li>Signaling overhead (header, control pkts) </li></ul></ul>
    13. 13. Low Power MAC for PicoNode <ul><li>Spread Spectrum Multi-Channel Scheme </li></ul><ul><ul><li>To Reduce Collision Rate </li></ul></ul><ul><ul><li>To Reduce Signaling Overhead (Shrink Address Space) </li></ul></ul><ul><li>Deep-Sleep Mode with Wakeup Radio </li></ul><ul><ul><li>Power Down the Whole Data Radio </li></ul></ul><ul><ul><li>Reduce Monitoring Energy Consumption by 10 3 Times </li></ul></ul>Adaptive Mobility Support
    14. 14. Outline <ul><li>Media Access and Existing Solutions </li></ul><ul><li>MAC for PicoNode Overview </li></ul><ul><li>Multi-Channel Scheme and Distributed Algorithm </li></ul><ul><li>Sleeping Mode Based on Ultra Low Power Wakeup Radio </li></ul><ul><li>Future Research, Design Methodology and Environment, Status and Time Line </li></ul>
    15. 15. CDMA Multi-Channel Scheme <ul><li>Parallel Transmission without Synch. </li></ul><ul><li>Implicit Local Address: Channel </li></ul>Idea: Nodes use different channels to transmit data, no collision at receiver. Key: Locally Unique with Global Reuse 1 3 2 4 5 6 7 8
    16. 16. Multiple Channel Assignment <ul><li>Sender based CA </li></ul><ul><li>No primary collision </li></ul><ul><li>Receiver need switch data channels </li></ul><ul><li>Needs a separate signaling channel </li></ul><ul><li>Receiver based CA </li></ul><ul><li>Primary collision </li></ul><ul><li>Receiver only listen to its own channel </li></ul><ul><li>No need signaling channel </li></ul>
    17. 17. Find the Solution: Graph Coloring <ul><li>Goal: For any node, all its neighbors are with different colors </li></ul><ul><li>Or : All two-hop neighbors with different colors. </li></ul><ul><li>Number of colors needed: </li></ul><ul><ul><li>#( NCA ) <= min { d(d-1)+1 , |v|} </li></ul></ul><ul><ul><li>Brook and Vizing theorem </li></ul></ul>Model: An incomplete graph G = (V,E) d is the maximum degree of nodes 1 2 3 4 5
    18. 18. Performance Analysis <ul><li>Model : a ∆ -regular graph </li></ul><ul><li>p : traffic density </li></ul>SC (Share Single Channel ): B sca = p (1-p) ( ∆-1) (1-p) RCA (Send on Receiver’s Channel ): B rca = p (1-p/ ∆ ) ( ∆-1) (1-p) TCA (Send on Sender’s Channel ): B tca = p [1-(1-p/ ∆ ) ∆ ](1-p)
    19. 19. CA Performance Analysis SC TCA RCA SC TCA RCA
    20. 20. Outline <ul><li>Media Access and Existing Solutions </li></ul><ul><li>MAC for PicoNode Overview </li></ul><ul><li>Multi-Channel MAC and Distributed Algorithm </li></ul><ul><li>Sleeping Mode Based on Ultra Low Power Wakeup Radio </li></ul><ul><li>Future Research, Design Methodology and Environment, Status and Time Line </li></ul>
    21. 21. Power Down Data Radio <ul><li>Current Radio Sleeping Mode: 10~50% Power Consumption </li></ul><ul><li>For PicoNode Running at 1% Duty Cycle, 90~95% Energy When Radio Is Idle. </li></ul><ul><li>Even Worse As PicoNode Radio Is Shorter Range </li></ul>150mW 50mW BWRC TCI 0.18W 1.48W 3W Lucent WaveLAN 23dBm 915MHz 0.18W 1.8W 1.825W Lucent WaveLAN 15dBm 915MHz 0.05W 0.6W 1.8W DEC Plessey DE 6003 2.4GHz Standby Receive Transmit
    22. 22. Sleeping mode signaling <ul><li>Problem : How To Send Data To a Sleeping Node? </li></ul><ul><li>Solution: </li></ul><ul><ul><li>Scheduling Wakeup </li></ul></ul><ul><ul><li>Reactive wakeup: Sender Send Beacon </li></ul></ul><ul><li>PicoNode chose to do reactive wakeup </li></ul>
    23. 23. Wake-up Radio <ul><li>Always running </li></ul><ul><ul><li>Super low power: 10 -4 ~ 10 -3 active mode power </li></ul></ul><ul><li>Data radio shut down when idle, and powered up by wake-up radio </li></ul><ul><li>Broadcast and uni-cast mode </li></ul><ul><li>Receiver response time: <10ms </li></ul>D/A Power Amplifier ED PPD Data/control codes Wakeup Tone X
    24. 24. Wakeup Sequence and Energy Profile <ul><li>E (useful data traffic) + E (overhead traffic) + E (idle) </li></ul>Node B DATA ACK Useful data Power Profile WUP CTS EPB = L (useful data traffic) * [1- p (collision)] T w T r T h Node A
    25. 25. EPB Performance Analysis L p = 20bits L p = 60bits L p = 300bits Radio Bit Rate R=10kbps Number of Channels M = 32 Network Dimention D = 6 Total Number of Nodes N=100 P s = 1uW P m = 2mw P r =3mw P t =2mw
    26. 26. EPB Performance Analysis P s = 1uW P s = 100uW P s = 1mW Conclusion: For duty cycle 1~10 percent: 10 ~ 100 times better
    27. 27. Outline <ul><li>Media Access and Existing Solutions </li></ul><ul><li>MAC for PicoNode Overview </li></ul><ul><li>Multi-Channel MAC and Distributed Algorithm </li></ul><ul><li>Sleeping Mode Based on Ultra Low Power Wakeup Radio </li></ul><ul><li>Future Research, Design Methodology and Environment, Status and Time Line </li></ul>
    28. 28. Things To Be Addressed <ul><li>Topology Control </li></ul><ul><li>Equal Transmission Power, Results in Bad Connectivity </li></ul><ul><li>Proposed Solution: Link-based Transmission Power Management to reach a ‘good’ network connectivity </li></ul><ul><ul><li>Power, Traffic Aware </li></ul></ul>
    29. 29. Design Flow & Environment Algorithm Exploration/Evaluation System Simulation Performance Evaluation SDL Functional Verification Documentation Test-Bench Prototyping Measurements System Definition Abstraction VCC Architecture Exploration Evaluation I II
    30. 30. Conclusion <ul><li>Create General-Purpose Tools and Vertical Design Methodology for Application Driven Low Power Protocol Design </li></ul><ul><li>A Low Power MAC Design Based on DMCA and Wakeup Radio </li></ul><ul><li>A Flexible and Clean MAC Interface for Upper Layer to Do Aggressive Tradeoff between Communication and Computation. </li></ul><ul><li>Motivate More Innovations in Radio Architecture for Low Power System </li></ul>
    31. 31. Q & A Thanks !

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