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

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

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

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

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