RRH Clustering in Cloud Radio Access Networks

Cloud Radio Access Network (C-RAN) offers an evolution in base stations architecture. The base station is broken down into a Base Band Unit (BBU) and a Remote Radio Head (RRH). While BBUs are pooled in a single geographical point, RRHs are distributed across multiple sites. In conventional architectures, a one-to-one logical mapping exists between BBUs and RRHs. One BBU is assigned to one RRH, so as to maximize network capacity. However, in the C-RAN architecture, a one-to-many logical mapping may be established. One BBU is assigned to many RRHs, so as to reduce network power consumption. In this paper, we investigate the BBU-RRH mapping, also known as the RRH clustering problem, and formulate it as a bin packing problem. Optimal and heuristic solutions are derived to reduce network power consumption, without compromising user quality of service. Simulation results illustrate the benefits from clustering RRHs, and prove that our heuristic achieves close performance to the optimal solution.