AT&T and Intel say that they have co-developed an approach that “[frees] 5G radios” from dedicated base stations. This “RAN pooling” brings the concept of elastic scaling from cloud computing into the Radio Access Network.
As of 2020, AT&T noted in a release, it has virtualized more than 75% of its network functions. But the Radio Access Network is sort of a last frontier for virtualization. The carrier goes on to explain why it’s so challenging: “The RAN base station distributed units (DUs) are one of the most distributed, resource intensive, and complicated parts of a wireless network” because they do the translation of data packets to/from radio waveforms for wireless transmission and reception. “DUs have to coordinate with radios in microseconds. … [They] have to extract meaningful signals from noisy waveforms with all kinds of signal interference, and they are responsible for making sure that radio spectrum, a valuable and limited natural resource worth billions, is shared fairly and efficiently across all the other users in the neighborhood.”
In other words, the level of performance demanded is extremely high, so radios rely on a physical link (often fiber) to dedicated baseband equipment, which runs constantly. However, one of the promises of 5G is that network intelligence and flexibility will increase, in order for network elements—including those in the RAN—to be able to go into sleep mode at times when they aren’t being utilized, to reduce the overall power usage of the network.
AT&T says that working with Intel, it has taken a step in that direction, which it has dubbed Advanced DU pooling. Advanced or Class II pooling allows one 5G radio to distribute its baseband processing across multiple servers, the carrier explained —so that even users on different devices, running different applications, in the same cell sector might have their data processed on different baseband servers. AT&T said that this “gives unprecedented elasticity and flexibility to the network to distribute (and redistribute) traffic instantly,” for baseband failover in the event of a server outage, or for consolidation of operations into fewer servers when usage is low, so that other servers can go to “sleep.”
The operator credited Open RAN standards between radios and DUs as helping to enable the development of advanced DU pooling.
The technology “will eventually be usable by the entire 5G operator community to drive the telecom industry’s goals of green and efficient wireless networks forward,” AT&T said. DU pooling works best with centralized RAN (C-RAN) deployments, the operator added, going on to say that it is working with its RAN vendors to incorporate DU pooling into commercial RAN software.