Effective Capacity in Multiple Access Channels with Arbitrary Inputs

TL;DR

This paper analyzes the effective capacity region of a two-user multiple access fading channel with arbitrary input distributions, optimizing power allocation and decoding order under QoS constraints to maximize sustainable data rates.

Contribution

It introduces a novel framework for characterizing the effective capacity region with arbitrary inputs and QoS constraints, including optimal power and decoding strategies.

Findings

Input signal distribution significantly affects capacity region.

Optimal decoding order depends on channel fading parameters.

Power allocation policies can maximize effective capacity under QoS constraints.

Abstract

In this paper, we consider a two-user multiple access fading channel under quality-of-service (QoS) constraints. We initially formulate the transmission rates for both transmitters, where the transmitters have arbitrarily distributed input signals. We assume that the receiver performs successive decoding with a certain order. Then, we establish the effective capacity region that provides the maximum allowable sustainable arrival rate region at the transmitters' buffers under QoS guarantees. Assuming limited transmission power budgets at the transmitters, we attain the power allocation policies that maximize the effective capacity region. As for the decoding order at the receiver, we characterize the optimal decoding order regions in the plane of channel fading parameters for given power allocation policies. In order to accomplish the aforementioned objectives, we make use of the relationship between the minimum mean square error and the first derivative of the mutual information with respect to the power allocation policies. Through numerical results, we display the impact of input signal distributions on the effective capacity region performance of this two-user multiple access fading channel.