Graph-coloring based resource allocation scheme in relay enhanced cellular system

Graph-coloring based spectrum resource allocation scheme for relay enhanced cellular (REC) system is proposed in this paper. During the signal transmission process, each subframe is split into two equal time slots (TSs). In TS1, spectrum resource allocation between base station to relay node (BS-RN) link and base station to user equipment (BS-UE) link is studied, while spectrum resources in TS2 are allocated to BS-UE link and RN-UE link. In TS1, traffic load based resource allocation scheme is applied, where the number of resources allocated to BS-RN link is according to the number of one-hop users and two-hop users. In TS2, co-channel interference is considered in the resource allocation process, which can mitigate strong interference between BS and UE, so as to achieve a higher data rate compared with conventional proportional fair (PF) resource allocation scheme. Simulation results show that the proposed scheme can obtain high average throughput as well as user fairness.