Threshold-Based Antenna Selection Algorithm for Dense Cloud Radio Access Networks

In this paper, we propose a threshold-based antenna selection algorithm for uplink dense cloud radio access networks (C- RANs), where a baseband processor unit (BBU) cloud is separately placed from densely deployed remote radio heads (RRHs). The proposed algorithm consists of two phases. In the first phase, each RRH determines whether to be included or not in a candidate set by using a predefined selection threshold. In the second phase, a RRH is randomly selected within the candidate set made in the first phase. By modeling the network with a homogeneous Poisson point process (PPP), the signal- to-interference ratio (SIR) complementary cumulative distribution function (CCDF) is derived when applying the proposed algorithm. Exploiting the derived expression, an approximate optimum selection threshold that maximizes the SIR coverage performance is obtained in terms of relevant system parameters, chiefly the SIR target, the pathloss exponent, and the RRH and user densities. Simulations demonstrate the performance of the obtained selection threshold. The key advantage of the proposed algorithm is its simplicity. Since the complexity caused by selecting a RRH is reasonable irrespective of the density of the RRH while guaranteeing the certain performance, the proposed algorithm is easily applied in a C-RAN where the RRHs are densely deployed.