Performance Analysis in SDR Based Fast Switching C-RAN Systems

Cloud radio access network (C-RAN) plays a more and more important role in next generation network researches. According to the C-RAN architecture, Base Band Units (BBUs) are centralized in a BBU pool and connected with the Remote Radio Heads (RRHs) through optical front-haul links. User Equipments (UEs) get access through the radio connection with RRHs. Much work has been done about the RRH-UE optimization schemes, but the BBU-RRH mapping study needs reinforcing, especially in the Software Defined Radio (SDR) based C-RAN systems. Virtual Machines (VMs) running as virtual gNBs are migrated between the BBUs to change the BBU-RRH combinations in a SDR based BBU pool. Load balancing methods are studied by designing different types of BBU-RRH switching schemes. Comprehensive performance analysis is necessary to provide guidance upon the research in BBU-RRH switching systems. In this paper, we analyze the mechanism of a SDR based C-RAN system detailedly, then we proposed an evaluation method taking backlog, idle resource and switching cost into account to evaluate the overall system performance. Power consumption and packet delivering mechanisms are investigated to analyze the indicators that represent the performance of a SDR based C-RAN system. Average packet delay, packet loss, outage probability and power consumption are all explored to show the system performance comprehensively. Relationship between the evaluation factors and the performance indicators is also discussed. Finally, simulation is carried out to analyze the performance of different switching schemes. Variations of performance indicators and evaluation results validate the evaluation method clearly.