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Title
Optimal Detection for a Distributed Transmission Array.

Authors
A. Hu, S. D. Servetto.

Status
In the Proceedings of the IEEE International Symposium on Information Theory (ISIT), Yokohama, Japan, June-July 2003.

Abstract
We consider the problem of communication over the reachback channel: this is a channel that arises in the context of wireless sensor networks, where multiple cheap and unreliable nodes pick up correlated samples of some spatial stochastic process, and then they need to communicate their observations back to a remote receiver. In this paper we consider the problem of designing a suitable transmitter for reachback. We assume that all the nodes agree on a common bit of information to send, and that all the sensor nodes cooperate to generate an aggregate signal that can reliably detected at a far location (even though, in general, the individual signals generated by each node cannot). An important challenge that we face is the fact that, with a large number of cheap and unreliable transmitters, it seems unlikely that these transmitters will be able to achieve high precision to synchronize their transmissions in the cooperative transmission step. We show in this paper how the problem of detecting signals generated with unreliable clocks is equivalent to detecting signals that undergo multipath fading, and use this equivalence to derive optimal detection structures for the signals generated by our distributed transmission array.

Download PDF file of abstract in proceedings (1 page).