TR2009-073

Relay-Coded Multi-User Cooperative Communications for Uplink LTE-Advanced 4G Systems



A technical consensus for future LTE-advanced 4G systems is the adoption of relay stations (RS) for letter link performance. While study in relay systems is often carried out for individual users independently, in this paper, we present a new design termed as relay-based multi-user cooperative communication specifically for the uplink of 4G systems. In this system, data streams from multiple users are coded at the relay with simple "addition" operations in the finite field. These coded data, instead of original data, will be forwarded by the RS to the base station (BS). A type of coding matrices with requirements of full rank and maximum information spreading is employed. With spreading information of one user to multiple data streams, the cooperative communication can be carried out for multiple users simultaneously, using a turbo decoding process that alternates decoding between a multi-user decoder and a number of single-user decoders. Experiments have demonstrated significant gains compared with a reference relay system where each user is processed individually.