Performance Analysis of Multicasting in Cloud-Radio Access Networks

Abstract

Cloud-radio access networks (C-RANs) are considered as energy efficient network architectures. Nevertheless, a dilemma in C-RAN architecture is to simultaneously optimize both spectral efficiency (SE) and energy efficiency (EE). In this paper, the tradeoff between SE and EE are studied considering a downlink multicasting transmission scenario in a C-RAN. In particular, to effectively mitigate the severe interference caused by densely deployed RRHs and improve the energy efficiency, a thinning scheme of RRHs is proposed. With a fixed diluted density of deployed active RRHs, the explicit closed-form expressions for coverage probability, SE and EE are derived by applying stochastic geometry. By using the obtained theoretical result as a utility function, a problem of optimizing the selection radius of RRHs is formulated to make a tradeoff between SE and EE for different preferences. Then, scalarization methods are proposed to give efficient solution. Numerical results validate the correctness and precision of performance analysis and show that the proposed approaches can generate an optimal selection radius of the thinning scheme.