Have Your Cake and Eat It Too! Enabling Frequency Diversity Through Opportunism

Edmund L. Wong and Sangmin Lee

ACM CoNEXT Student Workshop (CoNEXT SWS) 2010.

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Wireless networking

The broadcast nature of wireless networks is both a boon and a bane. On the one hand, multiple receivers may overhear a single transmission on the same channel at no additional cost above a point-to-point transmission; this property has been exploited in many opportunistic applications (e.g., [2]). On the other hand, the shared nature of the medium effectively forces wireless nodes to leverage frequency diversity and channelization for efficiency. Unfortunately, coordinating communication between nodes that may switch channels at any time is difficult and may in fact offset any performance gains from leveraging frequency diversity. In this paper, we describe lazily-assisted channel hopping (LACH) which utilizes opportunism to enable more frequency diversity. LACH consists of two techniques: flexible channel hopping, which gives nodes nearly complete freedom in switching channels in order to efficiently leverage available channels; and lazy opportunistic gossip, which helps nodes find one another by having nodes gossip schedules when unacknowledged transmissions are opportunistically overheard. Through these techniques, LACH enables nodes to dynamically adjust to diverse workloads, flexibly allocate their bandwidth, and efficiently find other nodes of interest.