Adaptive modulation and power in wireless communication systems with delay constraints

Abstract

This paper considers the problem of adaptive modulation and power in wireless systems with a strict delay constraint. Assuming perfect causal channel state information at the transmitter and the receiver, the modulation and power are dynamically adapted to minimize the outage probability for a fixed data rate. A slow frequency-flat channel is assumed and a discrete-time stationary Markov chain is used to model the time-varying channel. The problem is formulated as a finite-horizon discrete dynamic programming problem. The solution is a set of power/modulation allocation policies to be used during the transmission, as a function of the channel and system state. Numerical results show the gain of such adaptation policies in terms of average outage probability.