User association scheme in Cloud-RAN based small cell network with wireless virtualization

Cloud radio access network based small cell network (Cloud-RAN SCN) has been promising to meet the ever-increasing capacity demand of the future mobile networks. Within this network, since large amount of small cells exist and users move frequently, the reselection of access small cell for users becomes a great challenge. To encounter this challenge, in this paper, we study the user association scheme in the Cloud-RAN SCN scenario. Firstly, we establish a user association optimization problem with the aim of minimizing the network latency. The latency is deduced by minimal potential delay fairness function (MPDF). Moreover, considering the rising CO₂ emission and to guarantee the network throughput, energy saving and interference limitation are also incorporated in the optimization. To solve the user association optimization problem, three phrase search algorithm (TPSA) is proposed using the concept of Pareto Optimality. Under the help of TPSA, appropriate small cells and physical resources are chosen for users while minimizing the overall energy consumption and reducing the network interference. Various simulation results are shown to demonstrate the effectiveness of the proposed scheme.