Correlating RLF Reports via C-RNTI for SON Accuracy
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Solution Overview
Problem
Current failure event reporting in 3GPP networks lacks correlation with UE context, leading to double bookkeeping and unreliable mobility optimization decisions due to incompatible Rel-9 and Rel-10 methods, and delayed or lost RLF reports due to limited base station memory.
Innovation Solution
A method for correlating network-known information with failure event reports by using correlation information, such as C-RNTI or RACH preamble, during RRC re-establishment or establishment procedures to identify the UE and avoid double bookkeeping, even when base stations have limited storage for old UE contexts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the network uses both Rel-9 X2 RLF indication procedure and Rel-10 UE RLF report methods, then more failure information can be collected, but double bookkeeping occurs and failure statistics become unreliable
Solution Approach 1:
The patent introduces a correlation ID as an intermediary element that links the Rel-9 X2 RLF indication procedure and Rel-10 UE RLF report methods. The correlation ID is included in the RLF report from the UE and used by the network to identify and associate the corresponding X2 RLF indication, enabling unified processing of failure information from both methods without double bookkeeping
Solution Approach 2:
The patent merges the previously separate Rel-9 and Rel-10 failure reporting methods by introducing a common correlation mechanism. The X2 RLF indication procedure and UE RLF report are now correlated through the correlation ID, allowing the network to process both methods in a unified manner and maintain reliable failure statistics
2Measurement precision
If the base station stores UE context for long periods to enable correlation, then accurate failure analysis is possible, but memory resources are consumed excessively
Solution Approach 1:
The patent extracts the critical correlation information (correlation ID) from the complete UE context and transmits it to the target base station. This allows the source base station to release the full UE context after forwarding the RLF indication, while the target base station retains only the essential correlation ID needed for future RLF report matching, significantly reducing memory requirements
Solution Approach 2:
The patent performs preliminary action by including the correlation ID in the X2 RLF indication message sent to the target base station before the UE actually sends the RLF report. This prepares the target base station in advance with the necessary correlation information, so when the RLF report arrives, the correlation can be immediately established without requiring long-term storage of UE context at the source base station
Data Source
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AI summary
A method of failure event report correlation is proposed. A UE detects a failure event in a first cell served by a first base station, and the UE is assigned with a previous C-RNTI. The failure event may include a radio link failure, a handover failure, or a RACH failure. The UE then performs an RRC establishment procedure with a second base, and the UE is assigned with a new C-RNTI. After the RRC establishment, the UE transmits a failure event report along with the correlation information to the second base station. The second base station then forwards the failure event report and the previous C-RNTI to the first base station. The first base station can correlate the failure event report with the previous failure event based on the previous C-RNTI to avoid double bookkeeping and improve MRO decision for SON.