Joint Backhaul Co-scheduling and Relay Cell Extension in LTE-Advanced Networks

3GPP has standardized Type-1 in-band relay to be an integral part of LTE-A in order to meet the service coverage and performance requirement in a cost efficient manner. In an LTE-A relay network, users served directly by the eNodeB share resources with relay nodes communicating on the backhaul link. Besides, the end-to-end throughput of users served by RNs is determined by the achievable throughput on their access links and the available throughput on the relay backhaul link. As a consequence, the overall system performance is defined by the resource allocation strategy employed and resource balance maintained between the various links. Moreover, due to their low transmit power level in downlink, RNs have smaller cell coverage which creates unbalanced load distribution between the macro and relay cells. This further limits the performance of RN deployments. In this paper, the uplink performance of a relay enhanced LTE-A system is evaluated by utilizing a co-scheduling methodology at the donor eNodeB, where macro users are scheduled with RNs during the backhaul subframes, along with relay cell coverage extension to maintain a better load balance in the system. Furthermore, system optimization has been carried out by jointly considering uplink power control and backhaul subframe allocation. Simulation results show that the employed resource sharing strategy and cell coverage extension technique significantly improve the throughput achieved by the users in the uplink.