Resolving Entanglements in Topological Interference Management with Alternating Connectivity

TL;DR

This paper investigates the sum-capacity of a three-user interference network with time-varying channels, demonstrating that joint encoding over alternating states and state splitting are necessary for optimal performance.

Contribution

It introduces a novel approach combining state splitting and joint encoding to achieve sum-capacity in networks with limited channel state information.

Findings

Joint encoding over alternating states is essential for capacity achievement.

State splitting improves the efficiency of encoding strategies.

The proposed scheme is proven optimal via genie-aided upper bounds.

Abstract

The sum-capacity of a three user interference wired network for time-varying channels is considered. Due to the channel variations, it is assumed that the transmitters are only able to track the connectivity between the individual nodes, thus only the (alternating) state of the network is known. By considering a special subset of all possible states, we show that state splitting combined with joint encoding over the alternating states is required to achieve the sum-capacity. Regarding upper bounds, we use a genie aided approach to show the optimality of this scheme. This highlights that more involved transmit strategies are required for characterizing the degrees of freedom even if the transmitters have heavily restricted channel state information.