On the Capacity of the Diamond Half-Duplex Relay Channel

TL;DR

This paper analyzes the capacity of a diamond-shaped dual-hop relay channel with half-duplex relays, providing conditions under which a specific scheduling and forwarding scheme achieves the channel's capacity.

Contribution

It generalizes previous results by establishing a new condition involving power resources and channel gains for the optimality of the scheme.

Findings

The scheme achieves capacity when the product of active link capacities is equal in both phases.

Provides a more general condition for optimality beyond symmetric channel gains.

Extends understanding of relay channel capacity with practical power and channel considerations.

Abstract

We consider a diamond-shaped dual-hop communication system consisting a source, two parallel half-duplex relays and a destination. In a single antenna configuration, it has been previously shown that a two-phase node-scheduling algorithm, along with the decode and forward strategy can achieve the capacity of the diamond channel for a certain symmetric channel gains [1]. In this paper, we obtain a more general condition for the optimality of the scheme in terms of power resources and channel gains. In particular, it is proved that if the product of the capacity of the simultaneously active links are equal in both transmission phases, the scheme achieves the capacity of the channel.