Cooperative Relaying with State Available Non-Causally at the Relay

TL;DR

This paper investigates the capacity of a state-dependent relay channel with noncausal state information at the relay, providing bounds and capacity results for both discrete memoryless and Gaussian cases, including half-duplex scenarios.

Contribution

It introduces new coding schemes combining codeword splitting, Gel'fand-Pinsker binning, and dirty paper coding, and derives capacity bounds for the relay channel with noncausal state information.

Findings

Lower and upper bounds on capacity for DM and Gaussian channels.

Capacity is exactly determined in some degraded Gaussian cases.

Extends results to half-duplex relay operation.

Abstract

We consider a three-terminal state-dependent relay channel with the channel state noncausally available at only the relay. Such a model may be useful for designing cooperative wireless networks with some terminals equipped with cognition capabilities, i.e., the relay in our setup. In the discrete memoryless (DM) case, we establish lower and upper bounds on channel capacity. The lower bound is obtained by a coding scheme at the relay that uses a combination of codeword splitting, Gel'fand-Pinsker binning, and decode-and-forward relaying. The upper bound improves upon that obtained by assuming that the channel state is available at the source, the relay, and the destination. For the Gaussian case, we also derive lower and upper bounds on the capacity. The lower bound is obtained by a coding scheme at the relay that uses a combination of codeword splitting, generalized dirty paper coding, and decode-and-forward relaying; 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. In the case of degraded Gaussian channels, the lower bound meets with the upper bound for some special cases, and, so, the capacity is obtained for these cases. Furthermore, in the Gaussian case, we also extend the results to the case in which the relay operates in a half-duplex mode.