Issue link: https://hub.radisys.com/i/1302511
radisys.com 14 Radisys Series — Who Disaggregated My RAN? eBook capable of delivering 10+ Gpbs data rates whereas an LTE base station is capable of delivering <1 Gbps. As a result, operators need a new open protocol that can deliver these data rates. In 5G deployments, there are 2 transport options that are available for implementation of fronthaul for DUs and RUs: eCPRI and RoE. eCPRI (Enhanced CPRI): eCPRI is a packet-based fronthaul protocol defined by the CPRI Forum for handling 5G data rates. This protocol delivers higher data rates for 5G by using compression techniques for data transfer for optimized fronthaul. This efficiency, coupled with CPRI's dominance in LTE and 4G fronthaul, has led eCPRI to become the more popular protocol. More details can be found here. RoE (Radio over Ethernet): RoE is a protocol standardized by the IEEE 1914.3 working group. This protocol defines the encapsulation and mappings of radio protocols over Ethernet frames. Vendors are currently implementing RoE and a number of operators are encouraging the adoption of the RoE protocol for their 5G deployments. There was still some work to be done even after the availability of these two transport options. The O-RAN Alliance addressed the problem of fronthaul for 4G and 5G deployments in a very comprehensive manner. The specification provided a RAN split option (7.2x) that moved some of the PHY layer functionalities into the radio. This standard supports both eCPRI and RoE transport options. O-RAN Fronthaul: This open standard details all of the signaling formats and control messages needed for multivendor DU and RU equipment to interoperate. It supports both eCPRI and RoE transport mechanisms and it defines fronthaul for both 4G and 5G. The standard has been in development since 2017, with work on the standard beginning in the xRAN Forum and then continued by the O-RAN Alliance. The latest version of this specification is Release 3 which is now available on O-RAN alliance website (https://www.o-ran.org/specifications). The O-RAN Fronthaul specification anticipates all of the various scenarios regarding how a base station will interact with the radio, what the underlying 5G demands will be, time synchronization issues between two endpoints, and it make it deployment ready for operators. By addressing these various issues, the O-RAN standard is ensuring interoperability between base station and radio vendors, and we are already seeing commercial deployments using the O-RAN Fronthaul specification. O-RAN Fronthaul defines multiple planes of operations, including: • Control Plane (C-Plane): Messages define the scheduling, coordination needed for transferring data, including aspects of beamforming for 5G. • User Plane (U-Plane): Messages for efficient data transfer within the strict time limits of 5G numerologies. • Sync Plane (S-Plane): Addresses the timing and synchronization aspects between the DU and RU. • Management Plane (M-Plane): Defines the messages to manage the radio unit.