Two-TAG Timing Advance Handling in Multi-TRP CBRA
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Solution Overview
Problem
In multi-TRP wireless communication systems, UEs face challenges in identifying the correct TRP for applying timing advance (TA) commands received during contention-based random access (CBRA) due to a lack of synchronization signal block (SSB) association awareness, leading to potential misalignment in TA application.
Innovation Solution
A UE receives configurations for two timing advance groups (TAGs) from a network entity, obtaining a first TA value through CBRA and a second TA value through contention-free random access (CFRA), enabling a two-TAG operation to correctly apply TA commands to the appropriate TRP in a multi-DCI based multi-TRP scenario.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a UE performs contention-based random access (CBRA) in a multi-TRP system, then the UE can establish initial connectivity, but the UE cannot correctly identify which TRP to apply the timing advance (TA) command to due to lack of SSB association awareness
Solution Approach 1:
The patent introduces an intermediary mapping relationship between SSBs and TRPs. The network entity maintains knowledge of which SSBs are associated with which TRPs, and uses this mapping to correctly route TA commands to the appropriate TRP. This intermediary mapping mechanism resolves the information loss by providing a bridge between the UE's CBRA procedure and the network's TRP identification.
Solution Approach 2:
The patent segments the multi-TRP system into distinct SSB groups, where each SSB is associated with a specific TRP. By dividing the synchronization signal blocks and establishing separate associations with different TRPs, the system enables the UE to perform CBRA on a specific SSB while the network can identify the corresponding TRP based on the SSB-group mapping relationship.
2Measurement precision
If the network configures multiple TAGs for multi-TRP operation, then timing synchronization accuracy improves, but the system complexity and configuration overhead increase
Solution Approach 1:
The patent makes the SSB-to-TRP mapping relationship universal and reusable across multiple TAGs. Instead of creating separate mappings for each TAG, the system establishes a single SSB-group-to-TRP mapping that can be applied universally to identify the correct TRP for any TA command, regardless of which TAG is involved. This reduces configuration complexity while maintaining multi-TRP timing synchronization accuracy.
Solution Approach 2:
The patent performs preliminary configuration of the SSB-group mapping relationship before actual multi-TRP operations begin. By pre-establishing which SSBs belong to which TRP groups and storing this mapping information in the network entity, the system prepares the necessary identification structure in advance, avoiding the need for complex real-time decisions during TA command processing.
3Ease of operation
If the UE uses a single TAG for simplicity, then configuration complexity is reduced, but timing synchronization accuracy in multi-TRP scenarios deteriorates
Solution Approach 1:
The patent enables the system to serve itself by automatically maintaining and utilizing the SSB-group mapping relationship. The network entity automatically tracks which SSBs are associated with which TRPs based on the CBRA procedure, and uses this self-maintained mapping information to correctly apply TA commands to the appropriate TRP. This self-service mechanism provides multi-TRP timing synchronization accuracy without requiring complex manual configuration or additional UE actions.
Data Source
AI summary
A UE may receive, via a transceiver, a configuration of two TAGs for an SpCell from a network entity. The two TAGs may include a first TAG and a second TAG. The UE may receive, via the transceiver, a first TA value from a first network node based on a CBRA process. The UE may perform a single-TAG operation based on the first TAG and the first TA value. The UE may receive, via the transceiver, a second TA value associated with the second TAG from a second network node based on a CFRA process associated with the second TAG. The UE may perform a two-TAG operation based on the first TAG, the first TA value, the second TAG, and the second TA value.