Multi-hop relay for next-generation wireless access networks

Recently, there has been an upsurge of interest in multi-hop relay in both academia and industry. By breaking a long distance low quality link into two or more high quality segments, multi-hop relay is introduced to enable traffic/signaling forwarding between the base station and mobile user. Coverage is effectively extended to heavily shadowed areas in the cell or other distant areas beyond cell range by multi-hop relay. Meanwhile, it also provides throughput enhancement, especially at the cell edge. This paper first reviews the key technical advances with multi-hop relay in cellular networks. Then, novel technical solutions and algorithms for multi-hop relay are introduced and analyzed, including the separation of control and data, effective signal-to-interference-plus-noise ratio (SINR)-based routing algorithms, and cooperative relay schemes. Through extensive system-level and link-level simulations, we present improvements in both capacity and coverage in multi-hop relay networks compared to the legacy cellular network.