Since mobile network operators not only need to satisfy user needs but also have to reduce operating cost (mainly electricity cost) to maintain long-term profitability under strict market competition, energy efficiency (EE), defined as capacity per energy cost, becomes a popular metric for designing mobile networks. For user-centric services, however, the metric of quality of experience (QoE) is more suitable than the metric of capacity or data rate. Therefore, in this paper, we consider a novel network design metric quality-energy efficiency (QEE), defined as the quality of experience achieved per energy consumed. By using QEE as the performance objective, we propose a framework to design user-centric green cloud-based radio access network (CRAN). In particular, the issues of fairness and fronthaul power consumption in C-RAN are taken into account. An efficient approach to solving the non-convex max-min optimization problem for the design of user-centric green C-RAN is proposed. Simulation results validate the near-optimal performance of the proposed algorithm and demonstrate the value of the proposed QEE metric for the design of energy-efficient user-centric CRAN.
['Jhe-Yi Lin', 'Chia-Han Lee', 'Hen-Wai Tsao']
On the optimization of user-centric energy-efficient C-RAN