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MAC Protocols

MAC Protocols. The Influence of Communication Patterns on the MAC Protocol Design. CSMA Protocol. Send when no-one else is sending Wait until air is clear. C. A. B. Hidden Node Problem. Nodes A and C can’t hear each other Collision happens at the receiver

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MAC Protocols

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  1. MAC Protocols The Influence of Communication Patterns on the MAC Protocol Design

  2. CSMA Protocol • Send when no-one else is sending • Wait until air is clear

  3. C A B Hidden Node Problem • Nodes A and C can’t hear each other • Collision happens at the receiver • Carrier detection happens at the sender

  4. Ready to send C A B Clear to send C A B Data C A B Collision Avoidance (MACA)

  5. Simulation Results Network protocol performance msglen=50 11 CSMA MACA 10 9 8 7 6 goodput msg/node/s 5 4 3 2 1 0 0 10 20 30 40 50 60 70 80 90 100 input msg/node/s

  6. Research Charter Look at MAC protocol performance from a communication pattern point of view

  7. Sink Routing • Sink routing gives directionality • Directionality lessens effect of hidden node problem

  8. Directionality Experiment • Grid network • Experiment 1: random communication • Experiment 2: directed communication • All other parameters are equal

  9. Simulation Results Direction experiment 400 350 300 MACA directed 250 CSMA directed MACA random 200 CSMA random goodput msg/s 150 100 50 0 0 100 200 300 400 500 600 700 800 900 1000 input msg/s

  10. Conclusions • Communication patterns do have an influence on the choice and design of the MAC layer protocol • If we design a MAC protocol for WSNs, we should take communication patterns into account

  11. Next Steps • Implement communication patterns in simulator • Implement energy model and more realistic radio propagation model • Test and optimize MAC protocols based on energy usage • Implement protocol on EYES node

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