Calibration algorithm for C-RAN BBU-RRH switching schemes

In face of the rapid growth of data traffic in cellular networks, Cloud Radio Access Network (C-RAN) architecture has been proposed as a solution to obtain better performance in terms of efficiency, expansibility, elasticity, stability and expenditure such as Capital Expenditure (CAPEX) and Operational Expenditure (OPEX). However, C-RAN demands a comprehensive evaluation model and accurate qualitative metrics for designing Base Band Unit (BBU) and Remote Radio Head (RRH) switching mechanism. Many literatures have studied an energy consumption model which discusses the optimized resource utilization and power saving compared with typical RAN architecture, but it seems that they did not consider how to guarantee the quality of service (QoS) that may require more limitation. This paper is the first to study the C-RAN to achieve the reasonable BBU-RRH switching with good QoS by considering two new factors, resource waste (ReW) and traffic backlog (TB), which directly affect system performance. New BBU-RRH switching model for C-RAN is proposed for finding out the loss indicated by ReW and TB. An algorithm that optimizes the QoS, resource utilization and power saving of system is derived and it contains two parameters called higher threshold (HT) and lower threshold (LT) that represent upper limit and lower limit of one BBU's resource utilization, respectively. And we provide a parameter Pu as the evaluation criteria for HT and LT. Numerical results validated theoretical analyses and revealed HT set to 0.85 and LT set to 0.35 as optimal configuration under the assumptions in this paper. Compared with existing literatures, this paper solves the calibration of HT and LT for C-RAN BBU-RRH switching schemes.