Rate Regions for Relay Broadcast Channels

TL;DR

This paper derives capacity bounds for various classes of relay broadcast channels, expanding understanding of their limits and capacities in different configurations, including degraded, semideterministic, and orthogonal cases.

Contribution

It provides new inner and outer bounds for the capacity regions of partially cooperative relay broadcast channels, including exact capacities for several special classes.

Findings

Capacity regions are established for semideterministic and orthogonal RBCs.

New bounds are derived for RBCs with degraded message sets.

Capacity is characterized for parallel RBCs with unmatched degraded subchannels.

Abstract

A partially cooperative relay broadcast channel (RBC) is a three-node network with one source node and two destination nodes (destinations 1 and 2) where destination 1 can act as a relay to assist destination 2. Inner and outer bounds on the capacity region of the discrete memoryless partially cooperative RBC are obtained. When the relay function is disabled, the inner and outer bounds reduce to new bounds on the capacity region of broadcast channels. Four classes of RBCs are studied in detail. For the partially cooperative RBC with degraded message sets, inner and outer bounds are obtained. For the semideterministic partially cooperative RBC and the orthogonal partially cooperative RBC, the capacity regions are established. For the parallel partially cooperative RBC with unmatched degraded subchannels, the capacity region is established for the case of degraded message sets. The capacity is also established when the source node has only a private message for destination 2, i.e., the channel reduces to a parallel relay channel with unmatched degraded subchannels.