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The near-RT RIC (RIC for short) Self-Health-Check flow fulfills the requirement that all systems need to monitor their own health – internal subsystems, hosted software, and external interfaces.  At configurable intervals, RIC is to trigger Health-Check requests to its internal common platform modules and hosted xAPPs.  Each platform module and each xAPP are required to support Health-Check requests and to perform a self-check. 


Platform Modules and xAPPs

The specific Health-Check validations are as follows (see flow diagram on Figure 1):


  • Health of RIC platform modules –
    • Ability to initiate a Health-check on each of the common platform modules within the RIC (e.g., logging, tracing, conflict manager, xAPP manager, subscription management, O1 Termination, A1 Mediator, etc.), store results and declare alarm/alert conditions [5 in Figure 1]
    • Ability for each common platform module in the RIC to perform a self-check [6]
      • Implementation Option[1]: The self-check can potentially leverage Kubernetes Liveness and Readiness probes. Liveness probes can be configured to execute a command, issue a http-get, and open a TCP socket against the container/pod.   Readiness probes can be configured to ensure the pod is ready before allowing it handle traffic.  To further check a module’s (pod) ability to communicate with other modules over RMR (RIC Message Router), each module could subscribe to its own topic, send a hello-world message regularly to itself and ensure it can send and receive messages.
    • Any alarm/alert conditions or clearing of alarms/alerts are sent immediately via the O1 VES interface. [7-8]
  • Health of xAPPs
    • Ability of RIC to invoke Health-check requests to each of the xAPP instances deployed on the RIC [9]
    • Ability of each xAPP to perform Health-checks on itself and respond back to the RIC [10]
      • Implementation Option: See Implementation Option above for platform modules.
    • Any alarm/alert conditions or clearing of alarms/alerts are sent immediately via the O1 VES interface. [7-8]

External Interfaces

For external interfaces, the RIC is responsible to check its interface functions - O1 Termination, A1 Mediator, and E2 Termination modules.  

In addition, heartbeats or keep-alive signals over O1 are verified by the NB clients invoking the O1.  

The RIC also checks heartbeat message come from RAN resources over the E2 interface.

Note: Since the role of RIC is to enable near realtime control loop actions, latency is an important set of telemetry to be collected and reported - E2 latency and RIC processing latency.  As RIC matures release over release, latency telemetry should be defined and implemented.




  • Health of E2 interface - Ability to send request downstream RAN resources (O-CU/O-DU) via E2 interface for PM collection and report generation, and receive PM report [13-15]
    • Any alarm/alert conditions or clearing of alarms/alerts are sent immediately via the O1 VES interface. [16]
  • Health of Overall RIC Instance based on Health-Check results (successes, failures and anomalies), mapped to alarms and alerts (which represent RIC’s operability) are stored . [17]
    • Ability to update alarms for queries by NB clients. For example, RIC alarms/alerts can be incorporated into the O1 NetConf operational tree.  The corresponding Yang model might need to be augmented (e.g., define health state leaf with alarm-list in the Yang model).
  • Ability to make performance test results available to NB clients (for on-demand requests) [19-22]


To support this flow, a new Health-Check functional block within the RIC is being proposed, which can be implemented as a separate software module or as distributed function across one or more existing modules.  The Health-Check functional block has to perform the following:

  • Perform health-checks on the underlying common platform functions/modules and on xAPP instances hosted on the RIC (self-checks at configured intervals and on-demand requests)
  • Map failures and anomalies to alarms and alerts
  • Send out notifications for alarms and alerts
  • Determine the state of the RIC based on alarms and alerts
  • Store health-check results for queries
  • Clear alarms and alerts when conditions clear


Figure 1 below shows the flow of RIC Self-Checks – regular heartbeats over O1 and A1, the Health-Check Module initiating health-check requests within the RIC to assess its overall health, and issuing alarms/alerts, as appropriate based on health results.

<<insert sequence diagram and plantuml syntax>> RIC Self-Check SMO O-RAN RIC «OAM»O1 «OAM»O1 «NONRTRIC»Non-RT RIC «NONRTRIC»Non-RT RIC «RIC»A1 MED «RIC»A1 MED «RIC»O1 TERM «RIC»O1 TERM «RIC»HealthCk Function «RIC»HealthCk Function «RIC»Platform Modules «RIC»Platform Modules «RICAPP»xAPPs «RICAPP»xAPPs «SIM»E2 Node «SIM»E2 Node Alarms/Alerts from individual RIC Platform Modules and xAPPs Note: Apart from Health-Checks, a platform module or xAPP may generate an alarm/alert (orits clearing) when it encounters a failure/error (e.g., failure to reach another module) 1Platform Module Alarm/Alert/Clear 2«O1VES» Alarm/Alert or Clear 3xAPP Alarm/Alert/Clear 4«O1VES» Alarm/Alert or Clear RIC Self-Checks @ Regular Intervals Support HealthCheck Telemetry (FM, Heartbeat, PM) RIC Self-Checks Initiated loop for each Platform Module 5Perform HealthCheck Support Platform Module HealthCheck 6HealthCheck Status 7Platform Module Alarm/Alert/Clear 8«O1VES» Alarm/Alert or Clear loop for each xAPP instance deployed 9Perform HealthCheck 10HealthCheck Status Support xAPP HealthCheck 11xAPP Alarm/Alert/Clear 12«O1VES» Alarm/Alert or Clear 13«E2» Generate Report Support E2 Test Message Processing 14«E2» REPORT 15  Calculate report size response times as PM measures 16E2 Alarm/Alert/Clear 17«O1VES» Alarm/Alert or Clear 18Store all HC results in yang model Support Alarm Retrieval from SMO, Dashboard alt[If HC is performed on-demand, make file available to client] Publish Results 19Performance File Available 20«O1VES» HealthCheck Performance File Available 21«O1»Get PM Report File 22Make PM File Available for Sharing

Note 1: Figure 1 above shows the flows assuming that SMO is the northbound client that triggers the near-RT RIC.  The SMO consists of the O1 OAM adapter (supporting both O1VES and O1NetConf related messages/data) and the non-RT RIC (containing the A1 adapter).  The O-RAN SC implementation of the flows associated with this Health-check use case should create a simulated SMO for invoking requests and processing responses.  The simulated SMO should also provide a Test Driver (shown in Figures 2-4) for initiating requests to SMO and receive response from SMO.  Alternatively, a Dashboard can also be the NB client to trigger these requests.


[1] Implementation options are suggested at the use case level, to be further fleshed out during user stories phase.





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