Cooperative communication with feedback via stochastic approximation

This paper develops cooperative communication strategies based upon linear stochastic approximation algorithms for the Gaussian relay channel with several configurations of perfect and noisy feedback. In addition to being simple, the strategies can be shown to provide doubly exponential error decay in the case of perfect feedback and appealing tradeoffs between effective transmission rate and reliability in the case of noisy feedback. By contrast, straightforward application of the classic Schalkwijk-Kailath schemes offer enhanced rate or reliability in the presence of noisy feedback, but do not provide a tradeoff between the two.