Rate and Power Allocation in Fading Multiple Access Channels

TL;DR

This paper investigates optimal rate and power allocation strategies in fading multiple access channels to maximize utility functions, providing solutions for scenarios with and without power control or known channel statistics.

Contribution

It extends existing work by addressing general concave utility functions and analyzing both power control and no-control cases with performance bounds.

Findings

Optimal policies can be greedily obtained with known channel statistics.

Performance bounds depend on channel variations and utility function structure.

Greedy rate allocation performs close to optimal under certain conditions.

Abstract

We consider the problem of rate and power allocation in a fading multiple-access channel. Our objective is to obtain rate and power allocation policies that maximize a utility function defined over average transmission rates. In contrast with the literature, which focuses on the linear case, we present results for general concave utility functions. We consider two cases. In the first case, we assume that power control is possible and channel statistics are known. In this case, we show that the optimal policies can be obtained greedily by maximizing a linear utility function at each channel state. In the second case, we assume that power control is not possible and channel statistics are not available. In this case, we define a greedy rate allocation policy and provide upper bounds on the performance difference between the optimal and the greedy policy. Our bounds highlight the dependence of the performance difference on the channel variations and the structure of the utility function.