5G RAN Architecture: C-RAN with NGFI

This chapter discusses Cloud Radio Access Networks (C-RAN), which has been viewed as one of the key RAN architectures for 5G networks. First, the basic concept and the initially defined architecture of C-RAN are recalled, including the major benefits in terms of acceleration of network deployment, cost reduction and facilitation of 5G technologies. Then the major challenges of C-RAN realization are analyzed. One of the key challenges lies in fronthaul (FH) transportation which may limit C-RAN implementation in 5G. To address the issue, a new FH interface called Next Generation Fronthaul Interface (NGFI) is proposed. The C-RAN architecture itself evolves with the NGFI interface. The design principles for NGFI are presented including decoupling the FH bandwidth from the number of antennas, decoupling cell and user equipment processing and focusing on high-performance-gain collaborative technologies. NGFI claims the advantages of reduced bandwidth as well as improved transmission efficiency by exploiting the tidal wave effect of mobile network traffic. The transmission of NGFI is Ethernet-based to enjoy the benefits of flexibility and reliability. The major impact, challenges and potential solutions of Ethernet-based FH network are also analyzed. In addition, a prototype is developed and presented to verify NGFI.