In my previous two blogs in this three-part series, I covered O-RAN Architecture and SMO and Non-Real-Time Radio Intelligent Controller (non-RT RIC) : Data driven RAN optimizer topics. In this last blog of the series, we will look at a traffic steering example Non-RT RIC use case that deals with optimizing traffic management or achieving balanced cell load.
The Non-RT RIC configures the desired optimization policies, utilizes the right performance criteria, and leverages machine learning to enable intelligent and proactive traffic steering control. This use case is primarily based on the O-RAN architecture and its constituent entities.
As a refresher from the first blog in this series, here are the roles of each of the entities from a traffic steering use case point of view:
1. Retrieve necessary performance, configuration, and related data for defining and updating policies to guide the behavior of traffic steering function in the near-RT RIC.
2. Support communication of policies and enrichment information to the near-RT RIC and measurement configuration parameters to RAN nodes.
1. Support interpretation and enforcement of policies from non-RT RIC.
2. Use enrichment information to optimize control function.
1. Send FM/PM/other data with required granularity to SMO.
The Non-RT RIC platform resides inside the SMO, collects the data, and derives analytics information which is used in the traffic steering use case and same can be extended to other use cases as well.
This section deals with the traffic management in RAN according to defined policies and configuration.
The Non-RT RIC platform monitors the performance data and different counters from the various E2 nodes. Based on the trigger (defined by operator) or a generated event, the Non-RT RIC initiates a change.
Let us look at an example scenario to describe the use of A1 for traffic steering, where the Non-RT RIC sends policies for allocation of the control plane (RRC) and the user plane for different services, identified by their 5QI (5G Quality Service Indicator).
Cell A & B:
Cell C & D:
In the scenario a UE with UEid=9999999999, belonging to a subnet slice identified by S-NSSAI=10, having a Voice (5QI=1) and an MBB (5QI=9) connection established, enters an area covered by four frequency bands.
The Non-RT RIC understands the requirements and characteristics of the services and decides to let the Voice and RRC connection reside on the low band (here covered by a macro cell B becoming the PCell), while the MBB (MobileBroadBand) connection should preferably use the higher band (here provided by small cells C and D becoming the SCells) and avoid the low band if possible. Cell A is used for MBB if required for coverage reasons.
We have seen how the Non-RT RIC can take decisions on pushing the optimal policies to the Near-RT RIC based on the cell characteristics. This use case explains this capability of the Non-RT RIC in the traffic steering example and the same principles can be applied to various other scenarios as well.
References: O-RAN specification documents
Images credit: O-RAN-SC