O-RAN SC Release A requirements 2019-06-18 Rittwik Jana, David Kinsey, John Jensen, Matti Hiltunen AT&T

O-RAN: Open RAN Alliance http://www.o-ran.org 80+ companies: major operators, vendors, startups New end-to-end architecture for 5G Disaggregation to accelerate innovation Infrastructure “Cloudification” RIC is key architectural element Robust ecosystem through standardized interfaces Standardize A1, E2, O1, fronthaul, X2, F1, E1, cloud interfaces Unified, Operator Driven Standards Approach Influence and Drive 3GPP Standards O-RAN-SC: Open source community https://o-ran-sc.org/

O-RAN SC Presentation by Hank Kafka O-RAN SC, https://o-ran-sc.org/ORAN_SC_presentation.pdf

ORAN-SC and O-RAN workflow Request to resolve standard/OSC variance in cases where code diverges from spec TOC prioritizes and negotiates with O-RAN on behalf of OSC TIFG Test specs TOC Recommended spec/design features for inclusion in particular release WG1 S/W committee selects requests from WG1 based on available resources and timelines S/W subcommittee Release planning Define O-RAN end-to-end priority use case Select/recommend features from each WG to be included in a particular use case Coordinate between WGs to ensure required specs are available by certain date OSC AAL Pre-standards development and code contributions O-DU Design/ spec O-CU xApps O-RAN OS Wiki CU, DU, RU WG 7,8 RIC Sim VIM, NMS WG 5,6 O-RAN WG software releases to O-RAN for testing end-to-end use cases RIC, OFH WG 3,4 O-RAN Specs/ Architecture/ Reference design WG 1,2 Use Contribute ORAN WG contributions from O-RAN members (non OSC) Engage other open source communities

O-RAN SC Timeline

Release A objectives Demonstrate a working reference implementation of a full end-to-end O-RAN stack. Non-RT RIC (e.g., ONAP) implementing a basic A1 interface, metrics collection infrastructure Near-RT RIC framework implementing Application/microservices framework to host multiple xApps (e.g., AdmissionControl, Reporting, UE manager) A policy driven low latency messaging layer with its management component (Routing Manager) Subscription Manager for managing subscription through the E2 interface A1 mediator to relay basic policies from ONAP to RIC R-NIB database to store RAN state information E2 Termination agent to interface with O-CU E2 manager to write E2 data into the R-NIB OA&M – Control the RIC and xApps, Dashboard/portal to display FM and PM counters/KPIs from RIC Infrastructure - A virtualization layer based on COTS platform (e.g., Akraino) Simulator - A basic E2 interface agent via open source simulator (gNb side) O-CU implementation of an integrated eNB O-DU implementing L1 functional blocks L2 functional blocks OFH - Open Front Haul implementation O-RU not in scope

Projects

Epics Near-RT RIC - ~37 Epics RIC xApps – 15 Epics Non-RT RIC - 5 Epics OA&M, Dashboard portal – 5 Epics Infrastructure – 3 Epics Simulator – 2 Epics Integration and testing – 9 Epics Interface compliance testing – 3 Epics Use case testing – 2 Epics O-CU O-DU O-RU Epics will be added to JIRA soon https://wiki.o-ran-sc.org/display/RSAC/Contributions

Portal, Non RT RIC and Near RT RIC

Admission Control xApp A1 Mediator Dashboard A1 Mediator provides a simple (pre-standard) interface for communicating policy guidance to xApps. It translates translates an “intent” to the matching RMR message type and RMR will route the message to all the xApps that implement that particular intent. “Intent”: name + JSON schema for payload. Note: A1 Mediator decouple the xApps from the A1 interface protocol details (REST in our case) and an xApp only needs to “talk RMR” to process the E2 messages in real time control loops and receive policy guidance. Policy/intent (REST/JSON) Response (REST/JSON) REST A1 Mediator App PaaS Policy/intent (RMR/JSON) Response (RMR/JSON) Admission Control xApp App PaaS

xApps in RIC Sample xApp – Measurement analyzer xApp that computes KPIs from RNIB data (e.g., number of attached UEs) and provides them to a dashboard in the non-RT RIC Sample xApp – UE Manager xApp to subscribe for E2 messages and read these E2 messages to extract information from specific information elements (IEs). The information shall be stored into the near-RT RIC database (RNIB). The RNIB reflects the most recent RAN information state. Sample xApp - AdmissionControl xApp - The admission control xApp’s role will be to control the rate of admission of secondary NR bearers based on a specific criteria. This can be initially a very simple windowing algorithm based on rate of requests. In future, will be expanded to other overload/security scenarios. The admission control xAPP will subscribe to SgNB addition requests and make binary decisions (accept/reject) for each request. It will  function in both report mode (where it simply logs decisions made) and also in control mode (for simulators) where it will send back a Request Ack or Reject message. The Admission control xApp will also have an interface to A1 (via the A1- mediator) to accept policies which change the windowing parameters All xApps are configured and deployed via xApp Manager. Some xApps take policy guidance via A1 interface.

Admission Control xApp description

Measurement Analyzer xApp Measurement Analyzer xApp description Measurement Analyzer xApp App PaaS Subscibe to UE-NIB related notifications R-NIB DC added/removed for a UE Measurement Analyzer (MC) xApp utilizes information in the R-NIB to generate and report a number of metrics related to using dual connection in 5G. Examples of metrics: Number of connects/disconnect Duration of DC connections. DC connections/UE Dashboard DC metrics (VES event)

UE Manager xApp description App PaaS R-NIB UE Manager xApp subscribes (via E2) to X2 messages related to DC connection/disconnection and updates the R-NIB/UE-NIB. Examples of updates: DC established for UE at a GNB DC terminated for UE at GNB Update R-NIB/UE-NIB Subscibe to X2 messages related to DC gNB RIC INDICATION (X2 message)

E2/X2 Simulator Near-RT RIC RAN E2/X2Agent X2AP/E2AP Message Handlers ASN1 Codec SCTP Extension (load generator, NS3, etc.) E2/X2Agent Near-RT RIC E2 Termination E2/X2 X2 Agent implements X2AP for LTE eNB E2 Agent implements E2AP for 5G gNB X2AP/E2AP Message Generator RAN Initiated by Elementary Procedure Initiating Message Successful Outcome Unsuccessful Outcome   Response message RIC RIC Subscription (r1) RIC SUBSCRIPTION REQUEST (r1) RIC SUBSCRIPTION RESPONSE (r1) RIC SUBSCRIPTION FAILURE(>r2) RIC Subscription delete (r1) RIC SUBSCRIPTION DELETE REQUEST (r1) RIC SUBSCRIPTION DELETE RESPONSE (r1) RIC SUBSCRIPTION DELETE FAILURE(>r2) RIC or RAN E2 Reset (r1) E2 Setup (r1) [EN-DC]/- X2 SETUP REQUEST [EN-DC]/- X2 SETUP RESPONSE [EN-DC]/- X2 SETUP FAILURE Resource Status Reporting Initiation (r2) RESOURCE STATUS REQUEST RESOURCE STATUS RESPONSE RESOURCE STATUS FAILURE

Open Testing Framework, OTF

Next steps Steps we have planned for in the timeline, e.g. Input epics into JIRA PTL to add user stories Groom tasks into specific release A selection What we’re asking the O-RAN WG members to do for us Review & comment on requirements doc Invite to participate in OSC effort via meeting attendance Sign up to contribute source code, test cases, documentation, etc.

Automation Control Loops in the RAN Training Cache Service Management and Orchestration Fraemwork (ONAP) 3rd Party Apps at the edge APIs Design Inventory Policy Configuration Non-realtime RIC A1 5G RAN Near-real-time RAN Intelligent Controller (RIC) Loop 3: > 0.5 sec (policies, orchestration, SON) Application Layer Radio Network Information Base 3rd Party App Radio Connection Mgt. Mobility Mgt. Loop 1: per msec radio scheduling QoS Mgt. Interference Mgt. Trained Model Data Distribution Bus API Data from eNB Plug-in/ Mediator E2 Radio Distributed Unit F1 Centralized Unit Control plane Centralized Unit Data plane E2 Radio E1 Virtualization Layer with off-the-shelf open hardware platform Loop 2: 10 – 500 msecs (area resource optimization) 4G RAN eNB Cell Sites Edge Cloud Central Cloud

Benefits of control-plane disaggregation with RIC and ONAP Direct introduction of ONAP to the edge allowing E2E coverage Orchestration and optimization framework with dynamic policies Greater optimization benefits from centralized approach Better/larger network view, more centralized/holistic optimization solutions Vendor-agnostic solutions to provide consistent network benefits and user experience Current approach involves vendor specific solutions with widely different behaviors. Data enrichment via external data sources Use external data for better ML/AI algorithms that is not normally available within RAN domain (e.g. UE location, service type, mobility characteristics, etc.) Support new services and faster time to market Select best of breed solutions, easily insert AT&T secret sauce, faster dev time to support new features and services.

Example Dual Connectivity management using RIC 5G gNodeB contacts RIC whenever it gets a new session establishment request RIC uses policy guidance to accept/reject this request in near-real-time and determines traffic split between primary and secondary cells

Containerized micro-services based software design ONAP-based Portal RIC Dashboard Akraino GUI VES streaming data collector DMaap Portal RIC O1 O1/A1 App repo App Manager Routing Manager VES agent (Monitoring) Admission Control App Msmt Analyzer App UE manager Xapp A1 mediator App PaaS App PaaS App PaaS App PaaS App PaaS App PaaS App PaaS Logical event bus Fast path (ctrl loop) NNG/nanomsg Future: Persistent path (metrics, logs) Kafka Resource/Latency Manager DBaaS Redis App PaaS App PaaS App PaaS E2 Termination ASN.1 over SCTP E2 Manager UE Manager Kubernetes cluster management: Akraino Radio Edge Cloud (REC) blueprint – 5 server micro-cluster LTE eNB CU DU 5G gNB X2 E2 PoC Labs - ATL E2 Agent EMS PCMD 22