Topological Interference Management with just Retransmission: What are the "Best" Topologies?

TL;DR

This paper investigates interference management in topology-aware wireless networks using retransmission schemes, establishing conditions for optimal symmetric DoF and demonstrating their practical relevance and rate improvements.

Contribution

It introduces a necessary and sufficient condition for achieving half symmetric DoF with retransmission schemes, linking topology to interference neutralization capabilities.

Findings

Half symmetric DoF is achievable under the identified topology condition.

Existence of a set of transmitters for interference neutralization is guaranteed when the condition is met.

Retransmission schemes provide practical throughput gains beyond asymptotic DoF results.

Abstract

We study the problem of interference management in fast fading wireless networks, in which the transmitters are only aware of network topology. We consider a class of retransmission-based schemes, where transmitters in the network are only allowed to resend their symbols in order to assist with the neutralization of interference at the receivers. We introduce a necessary and sufficient condition on the network topology, under which half symmetric degrees-of-freedom (DoF) is achievable through the considered retransmission-based schemes. This corresponds to the "best" topologies since half symmetric DoF is the highest possible value for the symmetric DoF in the presence of interference. We show that when the condition is satisfied, there always exists a set of carefully chosen transmitters in the network, such that by retransmission of their symbols at an appropriate time slot, we can neutralize all the interfering signals at the receivers. Quite surprisingly, we also show that for any given network topology, if we cannot achieve half symmetric DoF by retransmission-based schemes, then there does not exist any linear scheme that can do so. We also consider a practical network scenario that models cell edge users in a heterogeneous network, and show that the characterized condition on the network topology occurs frequently. Furthermore, we numerically evaluate the achievable rates of the DoF-optimal retransmission-based scheme in such network scenario, and show that its throughput gain is not restricted to the asymptotic DoF analysis.