In a video interview, Analog Devices’ Nitin Sharma explains the company’s involvement with open RAN and the concept of a functional split.
Open radio access networks are all the talk at the network — as opposed to the wireless — side of 5G. While most of the talk surrounds the disaggregation of network functions, the “R” still stands for “radio.” While other functions such as baseband signal processing of the RAN may become virtualized, the radio is still the radio and that will always be hardware centric.
Analog Devices, which provides RF platforms for 5G, is heavily involved in the O-RAN Alliance, explains Nitin Sharma. Why? Because Sharma sees an open and standardized RAN as a key to innovation. Separating the RAN into a radio unit (RU or O-RU), a distribution unit (DU or O-DU), and a centralized unit (CU or O-CU) between the radio and the network core creates an open virtual RAN that’s ripe for innovation.
“Openness is powerful,” said Sharma in the video. “It will bring new choices for network functions.” Such an open ecosystem brings opportunities for new players to add value to networks. Networks where the RU, DU, and CU are contained in a single box lack that openness because the three functions are under single-company control.
The radio will, according to Sharma, stay hardware centric. Some radio functions can, however, reside in the RU or in the DU depending on the use case. That’s where the RU/DU split comes into play. At about 12:00 into the video, Sharma explains the partitioning of the RF and baseband signal processes in the RU and DU, saying “The radio is agnostic, it supports 5G, 4G, 3G, and 2G.” Thus, radio operations that precede 5G reside in the RU’s radio ICs while 5G can move some functions to the DU. That provides flexibility for upgrades, which are more difficult to implement when all functions reside in a single box, called a baseband unit (BBU). By moving baseband signal processing to the DU, third-parties can develop new network functions as needs arise. Implementation is simply a software upgrade.