Power Controlled Adaptive Sum-Capacity of Fading MACs with Distributed CSI

TL;DR

This paper derives the power-controlled adaptive sum-capacity for fading multiple-access channels with distributed CSI, proposing optimal strategies and bounds, and extending to scenarios with partial CSI sharing among transmitters.

Contribution

It introduces a throughput-optimal power-rate strategy for MACs with distributed CSI and provides bounds and extensions for non-identical channel statistics.

Findings

Proposed a power-rate strategy that is throughput optimal with identical channel statistics.

Developed an efficient implementation using successive cancellation and rate-splitting.

Established an upper bound for channels with non-identical laws.

Abstract

We consider the problem of finding optimal, fair and distributed power-rate strategies to achieve the sum capacity of the Gaussian multiple-access block-fading channel. In here, the transmitters have access to only their own fading coefficients, while the receiver has global access to all the fading coefficients. Outage is not permitted in any communication block. The resulting average sum-throughput is also known as `power-controlled adaptive sum-capacity', which appears as an open problem in literature. This paper presents the power-controlled adaptive sum-capacity of a wide-class of popular MAC models. In particular, we propose a power-rate strategy in the presence of distributed channel state information (CSI), which is throughput optimal when all the users have identical channel statistics. The proposed scheme also has an efficient implementation using successive cancellation and rate-splitting. We propose an upperbound when the channel laws are not identical. Furthermore, the optimal schemes are extended to situations in which each transmitter has additional finite-rate partial CSI on the link quality of others.