1. Exploring the Design Space of Sensor Networks Using Route-aware MAC Protocols Injong Rhee and Bob Fornaro Department of Computer Science North Carolina State University

2. Motivation and Goal Expanding design space Under extremely low energy budget Existing Sensor MAC Protocols New MAC schemes

3. Our approach: Route-aware MAC (RASMAC) On-demand routing paradigm (Directed diffusion, SPIN, etc) Route-awareness: the MAC layer of a node knows whether it is on a “currently active routing path” or not. If not on such a path, it switches off its radio. Reduce idle listening SINK

4. TDMA + Contention-based MAC Can we try to merge them together? Contention-based (802.11) Fast, but under high contention, low throughput TDMA Under low contention, slow Time synchronization Not scalable scheduling Not good for changes and mobility But, under high contention, high throughput and fair

5. Testbed: Wildlife tracking Endangered animals in NC (Red wolves, black bears, etc.) Current telemetry techniques are not adequate. Sensor networks can improve monitoring of these animals Our teams have been working with wildlife biologists and NC zoology association on this project.

6. Lab Testbed Testbed with 100 sensor nodes spread around a building in NCSU Study networking issues Congestion control MAC Routing issues. Applications: tracking, monitoring Not just for sensor networks, but general enough to study ad hoc, wireless mesh networks.

7. Route-aware MAC (RASMAC) If off, how does it know of a new active path? Software: Periodic synchronization Hardware: passive radio- powered trigger Decoupling of throughput and response time. Periodic synchronization ( Response time) Wake-up time duration (or frequency) while on active paths ( Throughput)

8. Performance results: Route-aware MACs RA-TDMA: Extremely low Energy budget Existing MAC RA-SMAC: Low energy budget c

9. Design choices : Existing approaches 802.11 Good service High energy TDMA: Good service Medium energy SMAC: Tradeoff (coupling of Throughput and Response time)