Terminal TCI Timing for Fast Beam and Cell Switching
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Solution Overview
Problem
The challenge in Rel-18 layer 1/layer 2 (L1/L2) based mobility is how to achieve fast beam switching and cell switch without ambiguity between the terminal equipment and the network device regarding the application timing of TCI states during cell switching.
Innovation Solution
The method involves configuring terminal equipment with candidate target cells and indicating TCI states and cell switches with specific time intervals, ensuring the TCI states are applied after a defined time interval has passed, thereby clarifying the application timing and enabling fast beam and cell switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the terminal equipment is indicated to switch to a non-serving cell and apply a TCI state, then fast beam switching and cell switch are achieved, but ambiguity arises between the terminal equipment and network device regarding the application timing of TCI states
Solution Approach 1:
The patent applies preliminary action by configuring the terminal equipment with candidate target cells and their associated time intervals before the actual cell switch occurs. The network device indicates the TCI state and switches the cell, and the terminal equipment determines the application timing based on the pre-configured time interval information, eliminating timing ambiguity before the switch happens.
Solution Approach 2:
The patent implements feedback by having the terminal equipment report capability information about supported time intervals to the network device. The network device then uses this feedback to appropriately configure and indicate the time interval for TCI state application, ensuring both parties have consistent understanding of the timing.
2Loss of time
If the terminal equipment applies TCI state immediately upon indication, then fast beam switching is achieved, but the terminal equipment and network device have different understanding of application timing
Solution Approach 1:
The patent uses preliminary action by pre-configuring candidate target cells with associated time intervals before the cell switch. This allows the terminal equipment to determine the correct application timing in advance, rather than immediately upon indication, ensuring both terminal and network device have consistent understanding while maintaining fast switching.
Solution Approach 2:
The patent applies dynamics by making the TCI state application timing flexible rather than fixed. The application time is determined based on the pre-configured time interval information and the specific indication received, allowing the system to adapt the timing to different scenarios while maintaining consistency between terminal and network device.
Data Source
AI summary
An apparatus, configured in a terminal equipment, includes: a receiver configured to: receive first configuration information, the first configuration information being used to configure one or more candidate target cells, and receive first indication information, the first indication information being used to indicate a first transmission configuration indication (TCI) state and cell switch; and a transmitter configured to transmit feedback information (HARQ-ACK); wherein after at least a first time interval is passed after the last symbol of the feedback information (HARQ-ACK), indicated first transmission configuration indication (TCI) state is applied in a first cell; the first indication information is used to indicate one or more candidate target cells and one primary target cell in the configured one or more candidate target cells, the primary target cell is one of the configured one or more candidate cells, and the first cell is the primary target cell.