Wireless performance and mobile fronthaul bandwidth of uplink joint reception with LLR combining in split-PHY processing

In this paper, we evaluate the wireless uplink performance and the mobile fronthaul (MFH) bandwidth of split-physical layer (PHY) processing (SPP), which is a base station (BS) functional split scheme used to link baseband units (BBUs) and remote radio heads (RRHs) in a centralized/cloud — radio access network (C-RAN). SPP enables MFH bandwidth reduction by splitting the BS functions between channel coding/decoding and modulation/demodulation within the PHY layer functions. SPP also enables high coordinated multipoint (CoMP) transmission and reception performance by employing uplink joint reception (JR) with log likelihood ratio (LLR) combining. Link level simulation results show that SPP with LLR combining achieves a block error rate (BLER) performance of 10% with a signal to noise ratio (SNR) penalty of less than 1 dB compared with that of conventional CRAN, which centralizes PHY layer functions in BBU. In addition, SPP has an SNR gain of more than 3 dB over medium access control (MAC)-PHY split, which splits the BS functions between the MAC and PHY layer functions. System level simulation results show that SPP with LLR combining improves the cell-edge user throughput by more than 33% over MAC-PHY split with selection combining and reduces the MFH bandwidth by 91% when compared with conventional C-RAN. Moreover, link and system level simulation results above are also observed when the channel estimation is non-ideal.