Enhancing performance of heterogeneous cloud radio access networks with efficient user association

Heterogeneous cloud radio access network (H-CRAN) is proposed as a cost-effective paradigm to meet the ever-increasing mobile data traffic demand, where the key idea is applying cloud computing technologies in a heterogeneous network (HetNet) to improve both spectral and energy efficiencies of the cellular system. In this paper, we investigate how to provide as many as possible users with QoS-guaranteed services in the H-CRAN. Our optimization task is to maximize the number of users with rate requirements for a given set of access points with bandwidth and transmission power budgets. We develop a novel user association strategy, where we present a Reference Power concept and develop an approximation algorithm to address the intractable user association problem. Numerical results indicate that our proposed user association strategy can not only increase the fully satisfied users significantly as compared to other methods, but also fulfill the capacity potential of the H-CRAN.