1. WiFlex: Flexible MAC protocols for Configurable Radios Jean Walrand and Wilson So EECS, UC Berkeley NSF Wireless Networking PI Meeting 10/14/2004

2. Observation Trend: Growing heterogeneity of devices with different data rate, range, and power requirements. Result: Growing number of PHY/MAC standards for different applications (i.e., point solutions). Drawback: Communications between heterogeneous devices require gateways. Interference between MACs. Question: Ignoring backward compatibility with existing MACs, is there a better solution?

3. Vision Vision: Family of interoperable MAC Protocols for various applications using configurable radios. Connectivity: sensors, PDAs, laptops, etc. interoperate. Flexibility: power, range, data rate tradeoffs Efficiency: given power & HW constraints, use spectrum efficiently.

4. Approach: PHY using OFDM Orthogonal Freq. Division Multiplexing Used in 802.11a, 802.16, HiperLAN/2, DAB, DVB-T, etc. Scalable in bandwidth (spectrum). Resilient against fading. Adaptive modulation/coding depending on application requirements and channel. Multi-Band Hopping: use available spectrum efficiently.

5. Bands, Carriers, Sequences Band 1 Band 2 Band 3 Unused Carrier Time

6. Approach: MAC MAC: Distributed link adaptation / negotiation  Number of bands; power; modulation Rendezvous  Specific hopping sequence (in and across bands) Medium access & scheduling  Backoff, priorities, holding time Coexistence of CBR & bursty traffic?

7. Project Plan 1. Characterize OFDM support of flexible power/range/rate tradeoff 2. Distributed link adaptation scheme 3. Distributed rendezvous mechanism 4. Medium access protocol 5. Evaluate medium access delay / throughput of MAC for different traffic patterns. 6. Deliverable: a family of MAC protocols achieving connectivity, flexibility, and spectrum efficiency

8. Remarks Web site (in progress): WiFLEX on www.eecs.berkeley.edu/~wlr