Radio Resource Management Scheme for Relieving Interference to MUEs in Relay-Based Cellular Networks

Relay nodes (RNs) have been recently introduced as a cost-effective solution to achieve ubiquitous high data rates in cellular networks. By providing a two-hop link between evolved nodeB (eNB) and user equipment (UE), RNs can improve the UE´s signal-to-interference-plus-noise ratio (SINR) and throughput. A typical relay-based cellular network is comprised of macro UEs (MUEs) that are served directly by eNB and relay UEs (RUEs) that are served via RNs. The performance of the entire network is degraded if the interference between RNs and MUEs is not carefully managed. In this paper, we propose a radio resource management scheme that effectively exploits the advantages of RNs without causing severe interference to MUEs, which yields a better overall network and cell-edge user throughput. To improve channel quality of MUEs located nearby RNs, the proposed scheme determines a specific set of subchannels to be used by each RN. Second, the proposed scheme assigns subchannels to UEs and RNs considering channel quality, average UE data rate, and the number of required subchannels at RNs. For resource allocation, we formulate a binary integer linear programming (BILP) problem and propose a novel heuristic algorithm to reduce its computational complexity. Our simulation results show that the heuristic algorithm achieves similar performance with the BILP. In addition, we discuss a detailed procedure for control signal exchange and data transmission and analyze the lower bound of SINR gain of MUEs obtained from the proposed scheme. It has been shown that the proposed scheme improves the overall network throughput and the cell-edge user throughput compared with existing schemes.