No Time to Countdown: Migrating Backoff to the Frequency Domain

Conventional WiFi networks perform channel contention in time domain. This is known to be wasteful because the channel is forced to remain idle, while all contending nodes are backing off for multiple time slots. This paper proposes to break away from convention and recreate the backing off operation in the frequency domain. The authors' basic idea leverages the observation that OFDM subcarriers can be treated as integer numbers. Thus, instead of picking random back-off duration in time, a contending node can signal on a randomly chosen subcarrier. By employing a second antenna to listen to all the subcarriers, each node can determine whether its chosen integer (or subcarrier) is the smallest among all others.

Provided by: Duke University Topic: Mobility Date Added: Mar 2011 Format: PDF

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