A channel access scheme for large dense packet radio networks

Abstract

Prior work in the eld of packet radio networks has often assumed a simple success-if-exclusive model of successful reception. This simple model is insucient to model interference in large dense packet radio networks accurately. In this paper we present a model that more closely approximates communication theory and the underlying physics of radio communication. Using this model we present a decentralized channel access scheme for scalable packet radio networks that is free of packet loss due to collisions and that at each hop requires no per-packet transmissions other than the single transmission used to convey the packet to the next-hop station. We also show that with a modest fraction of the radio spectrum, pessimistic assumptions about propagation resulting in maximum-possible self-interference, and an optimistic view of future signal processing capabilities that a self-organizing packet radio network may scale to millions of stations within a metro area with raw per-station rates in the hundreds of megabits per second.1 Introduction Multihop packet radio network technology oers an appealing prospect: that communication about a neighborhood or a metropolitan area might be a zero-cost commodity usable by all and capable of operation independent o f any wired infrastructure. Indeed there are already companies oering spread-spectrum radios that operate in license-free parts of the spectrum that can provide point-to-point links over a few kilometers between buildings. These radios are operated without coordination and are purchased and installed by the users. Might this anarchy grow and become the predominant means of communicating about a metropolitan area? Can a large number (millions) of packet radio stations concentrated in a metropolitan-sized area operate and

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