Achievable rate regions for Relay Channel with Private Messages with states known at the source

In this paper, we consider State-Dependent Relay Channel with Private Messages (SD-RCPM) as a generalization of the state-dependent relay channel, where the relay is both a source and a sink of data. We assume that the channel state is known only to the source and investigate two main cases: SD-RCPM with non-causal Channel State Information (CSI), and SD-RCPM with causal CSI. For non-causal case, we propose a coding scheme based on Gel´fand-Pinsker type coding at the source which is informed of CSI, and Decode-and-Forward (DF) scheme at the relay. Using Shannon´s strategy and DF scheme, we also propose a coding strategy for the causal case. Based on these coding strategies, we derive new achievable rate regions for this channel. Under special conditions, the derived achievable rate regions reduce to some previously known results. We also extend these achievable rate regions to Gaussian case. Providing numerical examples for the Gaussian case, we compare the derived achievable rate regions for different channel conditions.