Broadcasting over the Relay Channel with Oblivious Cooperative Strategy

TL;DR

This paper proposes a novel coding scheme combining Decode-and-Forward and Compress-and-Forward strategies for relay channels, improving capacity bounds and performance in scenarios with unknown relay strategies.

Contribution

It introduces a new integrated coding method for relay channels with mixed strategies and derives an inner bound on the capacity region for general memoryless broadcast relay channels.

Findings

The proposed coding improves the common rate in Gaussian broadcast relay channels.

An inner bound on the capacity region is derived for general memoryless broadcast relay channels.

The scheme enhances transmission efficiency in scenarios with unknown relay strategies.

Abstract

This paper investigates the problem of information transmission over the simultaneous relay channel with two users (or two possible channel outcomes) where for one of them the more suitable strategy is Decode-and-Forward (DF) while for the other one is Compress-and-Forward (CF). In this setting, it is assumed that the source wishes to send common and private informations to each of the users (or channel outcomes). This problem is relevant to: (i) the transmission of information over the broadcast relay channel (BRC) with different relaying strategies and (ii) the transmission of information over the conventional relay channel where the source is oblivious to the coding strategy of relay. A novel coding that integrates simultaneously DF and CF schemes is proposed and an inner bound on the capacity region is derived for the case of general memoryless BRCs. As special case, the Gaussian BRC is studied where it is shown that by means of the suggested broadcast coding the common rate can be improved compared to existing strategies. Applications of these results arise in broadcast scenarios with relays or in wireless scenarios where the source does not know whether the relay is collocated with the source or with the destination.