Cooperative Relaying with State Available at the Relay

TL;DR

This paper investigates the capacity of a state-dependent full-duplex relay channel where only the relay knows the channel state, deriving bounds and exact capacity in certain Gaussian cases using advanced coding schemes.

Contribution

It introduces new capacity bounds for relay channels with state information only at the relay, employing novel coding strategies like codeword splitting and generalized dirty paper coding.

Findings

Bounds on channel capacity are derived for discrete memoryless channels.

Bounds for Gaussian channels are established, with capacity identified in some cases.

The proposed coding schemes outperform those assuming full state knowledge at all nodes.

Abstract

We consider a state-dependent full-duplex relay channel with the state of the channel non-causally available at only the relay. In the framework of cooperative wireless networks, some specific terminals can be equipped with cognition capabilities, i.e, the relay in our model. In the discrete memoryless (DM) case, we derive lower and upper bounds on channel capacity. The lower bound is obtained by a coding scheme at the relay that consists in a combination of codeword splitting, Gel'fand-Pinsker binning, and a decode-and-forward scheme. The upper bound is better than that obtained by assuming that the channel state is available at the source and the destination as well. For the Gaussian case, we also derive lower and upper bounds on channel capacity. The lower bound is obtained by a coding scheme which is based on a combination of codeword splitting and Generalized dirty paper coding. The upper bound is also better than that obtained by assuming that the channel state is available at the source, the relay, and the destination. The two bounds meet, and so give the capacity, in some special cases for the degraded Gaussian case.