TCI Pre-Configuration for Low-Latency 5G Cell Switching
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Solution Overview
Problem
Existing 5G NR communication systems experience latency during inter-cell handovers due to additional beam training and management operations associated with TCI states, which are triggered by periodic reference signals, leading to inefficient switching between serving cells.
Innovation Solution
A method and apparatus are provided to reduce latency by configuring a UE to switch between cells based on a relationship of TCI states to reference signals measured prior to the switch indication, allowing for timely communication using the indicated TCI state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the UE waits for subsequent reference signal transmissions before activating TCI states, then measurement accuracy is improved, but handover latency increases
Solution Approach 1:
The UE performs beam training and measures reference signals in advance while still connected to the first cell, before the handover is actually triggered. This preliminary action allows the UE to have measurement results ready when the handover occurs, eliminating the need to wait for reference signals after switching to the second cell.
Solution Approach 2:
The patent uses mapping information as an intermediary that links TCI states to reference signals. This mapping allows the UE to identify which TCI states correspond to already-measured reference signals, enabling the UE to activate appropriate TCI states without waiting for new reference signal transmissions after handover.
2Reliability
If the UE performs additional beam training operations based on reference signals, then communication reliability is improved, but handover speed deteriorates
Solution Approach 1:
Beam training operations are performed in advance during the connection to the first cell, so that when handover occurs, the UE already has the necessary beam information and TCI states ready for reliable communication with the second cell, eliminating the need for additional beam training after handover.
Solution Approach 2:
The UE uses mapping information to copy or reuse measurement results from reference signals measured while connected to the first cell, applying them to TCI states for the second cell. This avoids the need to perform new beam training operations after handover, maintaining reliability while speeding up the process.
Data Source
AI summary
The apparatus may be a UE configured to receive, from a network node, a switch indication for the UE to switch from being served by a first cell to being served by a second cell. The apparatus may further be configured to receive a transmission configuration indication (TCI) state indication that indicates a TCI state for the UE to use with the second cell, where a first time period between the switch indication and the TCI state indication is based on a relationship of the TCI state to one or more reference signals measured by the UE prior to receiving the switch indication. The apparatus may also be configured to communicate with the network node via the second cell and using the TCI state.