Use of beamforming and interference mitigation techniques for relay backhaul enhancement

Relaying is one of the promising approaches for extending service coverage and improving quality of service. The self-backhauling of relays towards a serving (donor) eNode B provides cost-effective solution for deployment scenarios where conventional backhauling is either costly or unavailable. The end-to-end throughputs achievable by users served by relays are dependent on achievable throughputs on both the relay access and backhaul links. The 3GPP standardized Type 1 inband relay node (RN) employs a time-based resource partitioning between relay backhaul and access links. This resource allocation strategy coupled with sharing of eNode B (eNB) resources between the RN and users served directly by the eNB usually creates a backhaul bottleneck. The relay backhaul link performance is further degraded due to intercell interference, particularly on the cell edge where the deployment of relays are usually targeted. In this paper, the relay user's throughput enhancements by relaxation of relay backhaul bottlenecks are investigated through the use of beamforming and interference mitigation techniques. Simulation results demonstrate significant improvements in relay backhaul performance and end-to-end throughputs for relay users through the use of limited feedback beamforming and interference mitigation schemes.