WiFlex: Flexible MAC protocols for Configurable Radios

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WiFlex Flexible MAC protocols for Configurable
Radios

• Jean Walrand and Wilson So
• EECS, UC Berkeley
• NSF Wireless Networking PI Meeting
• 10/14/2004

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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?

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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.
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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.

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Bands, Carriers, Sequences










Band 1
Unused
Carrier
Band 2
Band 3
Time
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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?

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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

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Remarks

• Web site (in progress)WiFLEX
  onwww.eecs.berkeley.edu/wlr