Low-overhead distributed resource allocation in relay-assisted multi-cell OFDMA systems

In this paper, we design a resource allocation (RA) scheme for the downlink of relay-assisted orthogonal frequency division multiple access (OFDMA) cellular networks. Our design goal is to achieve a high spectral efficiency with low signaling and computational complexity. To alleviate the complexity, the proposed scheme allocates the resources in a distributed manner, where each relay station (RS) or base station (BS) individually performs a joint subchannel and power allocation for its subordinate users. To increase the spectral efficiency, the subchannel reuse among RSs is allowed. The intra-cell/inter-cell interference between RSs due to the subchannel reuse is mitigated by applying a fractional frequency reuse technique. The proposed scheme is composed of the resource allocation at RS (RS-RA) and the resource allocation at BS (BS-RA). The RS-RA is formulated as an optimization problem of which the objective is to minimize the number of allocated subchannels while guaranteeing minimum rate requirements of subordinate users. The optimization objective of BS-RA is to maximize the total throughput of direct users. Simulation results show that the proposed scheme can achieve a high spectral efficiency with low signaling overhead.