C-RAN Employing xRAN Functional Split: Complexity Analysis for 5G NR Remote Radio Unit

Fronthaul (FH) bandwidth in cloud radio access network (C-RAN) can be significantly reduced with an appropriate functional split by offloading more signal processing functionalities to the remote radio unit (RRU). However, this not only reduces the acclaimed centralization benefits but also increases the complexity of the RRU. Considering the practical aspects such as power consumption, cost, size and weight, it is often desirable to make RRUs as simple, yet efficient, as possible. In this paper, we analyze the complexity of the RRU with 5G New Radio (NR) considering functional split 7.2 as recently standardized split by the xRAN Forum. C-RAN with 5G NR allows to support a wide range of scenarios and use-case specific requirements. In addition, we compare suitability in terms of efficiency and flexibility of the RRU being implemented using either field programmable gate array (FPGA) or general purpose processor (GPP), e.g., x86 considering their computational requirements. Based on the complexity analysis, we calculate the required number of the FPGA or GPP to support the complexity of the RRU. We show that FPGA is more feasible option compared to x86 in terms of power consumption, particularly for rooftop-mounted RRU.