Fundamental Limits of Dynamic Interference Management with Flexible Message Assignments

TL;DR

This paper investigates the fundamental limits of interference management in linear networks with probabilistic link erasures, proposing new schemes and characterizing optimal message assignments to maximize degrees of freedom under fading conditions.

Contribution

It introduces new interference management schemes for erasure-prone networks, characterizes optimal message assignments, and analyzes the limits of cooperation strategies for different network sizes.

Findings

Optimal schemes improve average DoF at higher erasure probabilities.

For M=1, per user DoF is characterized for all erasure probabilities.

No universal message assignment strategy exists for all erasure probabilities.

Abstract

The problem of interference management is considered in the context of a linear interference network that is subject to long term channel fluctuations due to shadow fading. The fading model used is one where each link in the network is subject independently to erasure with probability p. It is assumed that each receiver in the network is interested in one unique message, which is made available at M transmitters. Optimal schemes from a Degrees of Freedom (DoF) viewpoint are analyzed for the setting of no erasures, and new schemes are proposed with better average DoF performance at higher probabilities of erasure. Additionally, for M=1, the average per user DoF is characterized for every value of p, and optimal message assignments are identified. For M>1, it is first established that there is no strategy for assigning messages to transmitters in networks that is optimal for all values of p. The optimal cooperative zero-forcing scheme for M=2 is then identified, and shown to be information-theoretically optimal when the size of the largest subnetwork that contains no erased links is at most five.