Bounds on the Capacity of the Relay Channel with Noncausal State Information at Source

TL;DR

This paper investigates the capacity limits of a relay channel where only the source has non-causal knowledge of the channel state, providing bounds for both discrete and Gaussian cases and highlighting near-optimal achievable strategies.

Contribution

It introduces new lower bounds for the discrete case and tighter bounds for the Gaussian case, improving understanding of relay channels with asymmetric state information.

Findings

Lower bounds for discrete memoryless relay channels with state

Tighter upper and lower bounds for Gaussian relay channels

Near-capacity-achieving strategies in certain rate regimes

Abstract

We consider a three-terminal state-dependent relay channel with the channel state available non-causally at only the source. Such a model may be of interest for node cooperation in the framework of cognition, i.e., collaborative signal transmission involving cognitive and non-cognitive radios. We study the capacity of this communication model. One principal problem in this setup is caused by the relay's not knowing the channel state. In the discrete memoryless (DM) case, we establish lower bounds on channel capacity. For the Gaussian case, we derive lower and upper bounds on the channel capacity. The upper bound is strictly better than the cut-set upper bound. We show that one of the developed lower bounds comes close to the upper bound, asymptotically, for certain ranges of rates.