Group Decoding for Multi-Relay Assisted Interference Channels

Chen Gong, Ali Tajer, Xiaodong Wang

Abstract: This paper proposes group decoding and analyzes the associated rate allocation schemes for the relay interference channel where multiple relays assist the transmissions from the sources to destinations. All the relays and destinations employ an advanced decoding strategy called constrained group decoding, where the desired messages are decoded jointly with some interferers' messages when doing so is beneficial. This paper considers two types of relay systems, the hopping relay system with no direct source-destination links, and the inband relay system with direct source-destination links. For each relay type, the objective is to design the relay assignment and the group decoding strategies at the relays and destinations, in order to maximize the minimum information rate among all source-destination pairs. For hopping relays with pre-specified relay assignments, we provide the optimal distributed algorithm for solving the above max-min rate allocation problem. Moreover, for hopping relays with dynamic relay assignments, and for inband relays, the problem becomes intractable and we offer heuristic schemes that perform close to the optimum solutions. Numerical results demonstrate the significant performance improvement provided by the proposed group decoder over the traditional systems that employ the linear minimum mean-square error (MMSE) decoders at both the relays and the destinations, where all interference is treated as noise, as well as the effectiveness of the proposed dynamic relay assignment strategies.