BBU-RRH Efficient Load Balancing Analysis For C-RAN

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 fewer Capital Expenditure(CAPEX) and Operational Expenditure (OPEX). How to make advantages more evident. the switching schemes of the separation of Base Band Unit(BBU) and Remote Radio Head (RRH) has become a hot topic. Besides,C-RAN also demands a comprehensive evaluation criterion and accurate qualitative metrics for designing BBU and RRH switching mechanism.This paper focuses on the criterion under real-time business model and discusses the switching schemes of the load balance technology. And then this paper optimizes the current algorithm and gives a new algorithm based on simulation results.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 that may require more limitation. This paper provide a real-time data model which count by one millisecond and I derive the amount of RRH’s data and BBU’s downlink resource capacity according to the LTE downlink resources.Then this paper designs a switching model by considering three new factors, resource waste (ReW), traffic backlog (TB) and switching cost(SCost). According to this model, a comprehensive evaluation criterion called switching punish (Pu) has been put forward, which is used to estimate the performance of the BBU-pool. And this criterion provides a basis for the switching algorithm. It is used to judge whether the switching algorithm is suitable for the BBU-pool or not in current scene.According to the above criterion, this paper give a new half adaptive switching algorithm. There are two significant factors called higher threshold (HT) and lower threshold (LT) which represent upper limit and lower limit of one BBU’s downlink resource utilization, respectively.Compared with existing literatures, this paper get HT 76 and LT 30 through simulation, which meas more reasonable than assumption. And then I find it is feasible for RRHto switch by itself after I get the result of simulation about Pu. So this paper define a threshold of Pu which is 95. And according to this threshold, this paper gives a more simple and reasonable adaptive switching algorithm.At last, the paper summarizes the content of the study, and then points out the problems which need to be modified and improved. Moreover, this paper indicates research trend of mobile communications.