Fronthaul for 5G: Low Bit-Rate Design Enabling Joint Transmission and Reception

Centralization of base-band processing in mobile networks is a key element of 5G architecture and aims to achieve significant performance and efficiency gains. Large transmission bandwidth and high number of antennas require an adaptation of Cloud Radio Access Network (C-RAN) architecture in order to realize efficient and affordable data transfer between remote units (RUs) included in the distributed access points (APs) and the Central Office (CO) which is the server processing data transmission of several cells. In this paper we propose a dynamic placement of physical layer processing functions that uses an affordable overall data-rate on the fronthaul links between RUs and the CO while allowing multi-cell joint processing both on the downlink and on the uplink. We take into account various practical constraints such as latency and synchronization to evaluate the feasibility of our solution. A tradeoff between fronthaul data-rate and RAN centralization enables joint processing to achieve higher spectral efficiency especially in dense networks in order to ensure high quality 5G mobile broadband service.