References
Use case overview and impacted components are described in the 5G OOF PCI optimization main wiki page.
1. Architecture
The architecture below depicts the SON-Handler MS as a part of DCAE. Only the relevant interactions and components are shown.
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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
- PM/FM data
1.3. DMaaP Client
This is responsible for registering with the DMaaP client for the DMaaP notifications from SDN-R and VES-Collector, and to Policy.
2. Core Logic components and Pre-processing algorithm
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The main actions in the various states are listed below:
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2.1.1. Initialization
In this state, the following actions are performed:
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2.1.2.4. Policy response handling
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- Response from policy is handled by a separate thread.
- When positive acknowledgement is received from the policy the cells in the response are removed from the table and when negative acknowledgement is received the negative_ack count for the cell is increased and updated in the table. When no response is received no changes are made.
- When negative_ack count of a particular cell increases beyond a threshold, it is shifted to another table.
2.1.2.5. Child Thread Status update handling
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These child threads are spawned for handling PCI optimization primarily, though they may also trigger PCI-ANR joint optimization in some cases. The various states and associated actions are described below.
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2.2.1 Initialization
In this state, perform initialization, and based on the type of notification, go to either Section 2.2.1.1 or 2.2.1.2 for next actions.
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- Send a PCI_opt request to OOF with cells triggering the request along with the trigger type
- Store details of request in DB.
- Wait for OOF optimization result.
Upon trigger from main thread with OOF PCI optimization result, prepare and send DMaaP messages to Policy: for the cells whose PCI value has changed, as well as to all the neighbors of the cells whose PCI value has changed. 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).
- Start Policy_rsp timer and wait for Policy response by going to "Wait for Policy Response" state (Section 2.2.6).
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Prepare DMaaP messages to Policy for the cells whose PCI value has changed, as well as to all the neighbors of the cells whose PCI value has changed. 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)
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if response contains NRT updates (corresponding to ANR)
Update/prepare DMaaP messages to Policy for the cells whose neighbors have undergone updates (with indication "HO prohibited"). 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)
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Send prepared message(s) to Policy.
- Start Policy_rsp timer and wait for Policy response by going to "Wait for Policy Response" state (Section 2.2.6).
2.2.6.
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Handling Policy Response
- Response from policy is handled by a separate thread.
- When positive acknowledgement is received from the policy, the cells in the response are removed from the table and when negative acknowledgement is received the negative_ack count for the cell is increased and updated in the table. When no response is received no changes are made.
- When negative_ack count of a particular cell increases beyond a threshold, it is shifted to another table.
2.2.7. Wait for RAN updates
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This child thread perform all PM-related computations, and initiate autonomous ANR updates based on HO metrics.
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2.3.1. Initialization
In this state, all data structures are initialized. This includes any processing-pending PM data, processed PM data and populating details from DB.
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When an indication that PCI-ANR child thread(s)' actions are completed is received, go to Step 2.3.2.2.1. If any PM inputs are received, go to Step 2.3.2.2
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Upon reception of Policy response or Policy_rsp timeout, check if any pending ANR updates are to be sent to Policy. If any present, then go to Step 2.3.2.2, else update PM-based ANR actions are completed, and go to "Wait for PM inputs" state (Section 2.3.2)..
2.3.4. Handling Policy response
- Response from policy is handled by a separate thread.
- When positive acknowledgement is received from the policy, the cells in the response are removed from the table and when negative acknowledgement is received the negative_ack count for the cell is increased and updated in the table. When no response is received no changes are made.
- When negative_ack count of a particular cell increases beyond a threshold, it is shifted to another table.