Near real time RIC and xApps market considerations

An extract from my upcoming report "Open RAN RIC and Apps 2023"   

As mentioned, near real time RIC and xApps capabilities are today embedded in gNodeB and RU/CU/DU code. The constraints of developing applications that have an actual effect in milliseconds on the RAN offer two main challenges, one technical, the second commercial.

The technical challenge associated with the development and roll out of xApps and the near real time RIC itself is related to the RAN Scheduler. The RAN scheduler, within the radio architecture is extremely processing intensive and is responsible, among other operations of the real time the uplink and downlink radio decoding and encoding.

Running concurrently with the L1/Phy, RLC and running on the MAC layer, the scheduler reads data from the upstream RLC and transmits to the downstream PHY. The scheduler effectively determines the number of bytes to transmit to each UE in real time.

Since the scheduler is in essence a real time forwarding engine, it is instantiated in the DU and the fronthaul connectivity should have less than 1ms latency to the RU. This stringent latency envelope requires extremely tight integration between the DU, the RU and the near real time RIC (and its associated xApps). While theoretically functionally feasible, the level of integration between all these vendors necessary to realize xApp with the appropriate level of control and performance is generally not there.

The vendors, naturally, first prioritize integration between their own products and in this case, the DU vendors are in control of that value chain.

Understanding that today, there is a very limited number of DU vendors, who are all in the process of realizing the O-RAN first generation implementation and integration, and understanding that all their resources are mobilized on commercial deployments where the priority is the functional, stable and performing implementation of RU, CU and DU, it is not a surprise that we do not see much multi vendor activity on near real time RIC, xApps integration with real RU and CU DU.

 

While we have several examples of trials with either non MIMO CU DU RU or proof of concepts with RU, CU, DU emulators, we are still far from real end to end deployment even in trial situation of a an end to end implementation close to commercial grade.

The second impediment to near real time RIC xApp multi vendor implementation is commercial and can be found in the report.