This letter analyzes the performance of an adaptive modulation system, taking into account additive noise and fading on the feedback channel. It is shown that these feedback channel imperfections could significantly degrade the throughput gains of adaptive modulation over nonadaptive transmission. Specifically, feedback errors can result in an outage region in the low signal-to-noise ratio region. Two feedback receivers are proposed: one is based on the finite-state Markov channel model; and the other is a generalized Bayesian receiver. These receivers reduce the outage region due to feedback errors, and they can complement or be used as alternatives to error-control coding schemes
['Anthony E. Ekpenyong', 'Yih-Fang Huang']
Feedback-detection strategies for adaptive modulation systems