Capacity enhancement through opportunistic activation of relays in Cloud RAN deployments

This paper considers a combination of Coordinated Multi Point Transmission (CoMP) and opportunistic relay activation to enhance capacity in highly dense deployments. The activation of a small number of relays, selected judiciously from a large candidate set, enhances performance by restricting CoMP transmission to those UEs for which channel conditions allow interference to be mitigated effectively. Two opportunistic relay activation algorithms are considered, based on geometry and utility-metrics, respectively. System-level evaluations illustrate that a noticeable capacity gain can be achieved with such techniques, especially at the cell-edge.