Sub-optimality of Treating Interference as Noise in the Cellular Uplink

TL;DR

This paper demonstrates that naive treating interference as noise (TIN) is suboptimal in a cellular uplink scenario involving a point-to-point and a MAC channel, and proposes a combined TIN and time division scheme that outperforms naive TIN.

Contribution

The paper shows the suboptimality of naive TIN in a specific interference network and introduces an improved scheme combining TIN with time division multiple access.

Findings

Naive TIN is never optimal in the considered network.

A combined TIN and time division scheme outperforms naive TIN.

An upper bound on the sum-capacity is derived.

Abstract

Despite the simplicity of the scheme of treating interference as noise (TIN), it was shown to be sum-capacity optimal in the Gaussian 2-user interference channel in \cite{ShangKramerChen,MotahariKhandani,AnnapureddyVeeravalli}. In this paper, an interference network consisting of a point-to-point channel interfering with a multiple access channel (MAC) is considered, with focus on the weak interference scenario. Naive TIN in this network is performed by using Gaussian codes at the transmitters, joint decoding at the MAC receiver while treating interference as noise, and single user decoding at the point-to-point receiver while treating both interferers as noise. It is shown that this naive TIN scheme is never optimal in this scenario. In fact, a scheme that combines both time division multiple access and TIN outperforms the naive TIN scheme. An upper bound on the sum-capacity of the given network is also derived.