References
Use case overview and impacted components are described in the 5G OOF PCI optimization main wiki page.
1. Architecture
This architecture depicts a standalone PCI micro-service. When this is moved to DCAE, it may undergo some adaptations, for e.g., the interfaces have to be adapted appropriately.
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This is a PostgreSQL DB, and is intended to persist information such as the following:
- PCI-Handler MS Config information (e.g., thresholds, timer values, OOF algorithm name, etc.)
- Pre-processing results and other related information (e.g., neighbor list)
- Buffered notifications (i.e., notifications not yet processed at all)
- State information
- Association between pnf-name and CellId
1.3. DMaaP Client
This is responsible for registering with the DMaaP client for the DMaaP notifications from SDN-R, and to Policy.
2. Core Logic components and Pre-processing algorithm
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The state transition diagram is illustrated below:
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The main actions in the various states are listed below:
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Buffer the notification (along with the cluster id) in the DB. Discard any older notifications (remove from the DB) from the same cell (which is buffered).
2.1.6. OOF Response Handling
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Upon receiving a terminate request clean up all resources.
2.2. Child Thread(s)
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2.2.1 Initialization
In this state, perform initialization, and transition to Cluster formation state.
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2.2.3. Wait for notifications
- Start notif_timer if not started already, and wait for more notifications
- If a new notification is received, transition to Cluster expansion statemodification state. If notif_timer expires, transition to Trigger OOF state.
2.2.4. Cluster
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modification
- If a cell that already exists in the cluster has sent a notification (for neighbor-list change), update the cell's neighbors appropriately in the existing cluster. Otherwise, 'attach' the cell appropriately in the existing cluster, and update the cell's neighbors.
- For each of the neighbors, fetch the neighbor list (via REST API) from SDN-R Config DB (i.e., fetch neighbor of neighbors of the cell that sent the neighbor list change notification).
- Extend Modify/extend the cluster appropriately.
- Determine collision/confusion by calling method determine_collision_confusion.
- Based on number of collisions/confusions and config policy, determine if OOF has to be triggered or more notifications should be awaited (handle also timeout case).
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Else
Start timer Wait for more notifications (timer must have been started during cluster formation)
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Note: When transitioning to this state from Handle buffered notifications state, more than 1 notification may have to be handled.
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Upon trigger from main thread with OOF PCI optimization result, prepare and send a DMaaP message to Policy (message layout available in Policy sub-page. The message payload layout shall be the same as the yang model contents for the configuration update to be sent by SDN-R towards the RAN. The pnf-name corresponding to the cell-ids can be fetched from Config DB of SDN-R (using REST API). (Note: The layout of the message from SDN-R to RAN is available in the SDN-R sub-page).
After sending the message to Policy, a status update is provided to the Main Thread for further actions.
2.2.7.
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Buffered notification handling
- If the main thread triggers a buffered notification to be handled, start buf_timer (if not started already) to buffer the notification (pre-configured value), if not already started (Note), and store the notification contents.
- Upon expiry of buf_timer, process the received (and stored) notifications by transitioning to Cluster ExpansionModification state.
- If new notifications are received when in this state, then simply store the notifications check on whether a notification was received and buffered for the same cell earlier, and if yes, discard the earlier notification (i.e., retain only the latest unprocessed notification for a cell). Simply store the notification and remain in this state.
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