The Deterministic Sum Capacity of a Multiple Access Channel Interfering with a Point to Point Link

TL;DR

This paper analyzes the sum capacity of a cellular-like network model using deterministic approximation, deriving bounds and coding schemes that optimize data rates through interference management techniques.

Contribution

It provides the first explicit characterization of sum capacity for a two-user multiple access channel interfering with a point-to-point link, including coding schemes and interference alignment strategies.

Findings

Sum capacity matches the interference channel when the weaker user is silenced.

Interference alignment improves sum rate in certain interference configurations.

Lower bounds on degrees of freedom for Gaussian channels are established.

Abstract

In this paper, we use the linear deterministic approximation model to study a two user multiple access channel mutually interfering with a point to point link, which represents a basic setup of a cellular system. We derive outer bounds on the achievable sum rate and construct coding schemes achieving the outer bounds. For a large parameter range, the sum capacity is identical to the sum capacity of the interference channel obtained by silencing the weaker user in the multiple access channel. For other interference configurations, the sum rate can be increased using interference alignment, which exploits the channel gain difference of the users in the multiple access channel. From these results, lower bounds on the generalized degrees of freedom for the Gaussian counterpart are derived.