UE Identity Selection for Inter-Cell mTRP Re-establishment
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Solution Overview
Problem
In the context of inter-cell multi-TRP configurations, User Equipment (UE) faces ambiguity in identifying its UE identity during re-establishment procedures, leading to failed connections and increased signaling requirements, as it is unclear which Physical Cell Identity (PCI) or Cell-Radio Network Temporary Identity (C-RNTI) to use, especially when transitioning between different network nodes.
Innovation Solution
The UE employs a selection function to determine a subset of cell parameters from its inter-cell mTRP configurations, such as PCIs and C-RNTIs, to set its identity in re-establishment requests, allowing for clear UE identification and context retrieval, even when configured with multiple cells, thereby facilitating faster reconnection and resolving ambiguity issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE uses multiple PCIs and C-RNTIs from inter-cell mTRP configurations for identification, then the adaptability and connection reliability are improved, but the device complexity and difficulty of detecting and measuring the correct identity increase
Solution Approach 1:
The patent changes the identification parameters by introducing a new UE identity format that includes both the original PCI/C-RNTI and an additional identifier indicating the specific TRP or cell configuration. This allows the network to distinguish between multiple PCIs and C-RNTIs configured for inter-cell mTRP, resolving the ambiguity in identifying the correct identity during re-establishment procedures.
Solution Approach 2:
The patent introduces an intermediary identifier (such as a TRP index or configuration index) that mediates between the multiple PCIs and C-RNTIs and the network's context retrieval mechanisms. This intermediary element allows the network to map the UE's composite identity to the correct stored context without requiring complex detection of multiple possible identities.
2Device complexity
If the UE falls back to RRC_IDLE for re-establishment, then the device complexity is reduced, but the productivity and connection speed are worsened due to increased signaling overhead and longer reconnection time
Solution Approach 1:
The patent applies preliminary action by pre-configuring the UE with multiple PCIs and C-RNTIs along with their associated identifiers during the initial connection setup or handover preparation. This allows the UE to immediately use the correct pre-selected identity for re-establishment without needing to fall back to RRC_IDLE, thereby maintaining connection state and reducing reconnection time while managing complexity through advance preparation.
3Measurement precision
If the UE includes complete UE context information in re-establishment requests, then the measurement precision and context retrieval accuracy are improved, but the loss of information and signaling overhead are reduced
Solution Approach 1:
The patent extracts only the essential identification elements (selected PCI, C-RNTI, and TRP/index identifier) from the complete UE context and includes them in the re-establishment request. This selective extraction maintains sufficient precision for the network to retrieve the correct UE context while minimizing signaling overhead by excluding redundant context information that can be re-obtained through context retrieval procedures.
Data Source
AI summary
There is provided a method performed by a user equipment (UE). The method comprises: receiving, from a first network node, one or more inter-cell multiple Transmission Reception Point (mTRP) configurations, wherein each configuration comprises one or more cell parameters determining one or more cell parameters from the received inter-cell mTRP configurations according to a selection function; and transmitting a message to a second network node, the message comprising a UE identifier, obtained from the selected one or more cell parameters.