Cell Handover Timing Advance for Low-Latency Uplink Sync
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Solution Overview
Problem
Conventional cell handover technologies experience significant delays due to the need for a terminal device to obtain information about the target cell after receiving a handover command, which is inadequate for low-latency and high-capacity services like XR and cloud gaming.
Innovation Solution
The method involves the terminal device obtaining timing advance (TA) information of a candidate cell before receiving the handover command, using first information provided by the network device, allowing the terminal to synchronize its uplink and perform data transmission immediately upon handover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the terminal device obtains target cell information after receiving the handover command, then the handover process is simple, but the handover delay increases
Solution Approach 1:
The terminal device performs downlink synchronization and obtains target cell information (including TA values) before receiving the handover command. This preliminary action allows the terminal to be ready for immediate uplink transmission upon handover, reducing handover delay while managing complexity through conditional execution based on configuration parameters
2Reliability
If the terminal device performs downlink synchronization before handover, then uplink synchronization is improved, but the terminal needs to handle multiple synchronization states
Solution Approach 1:
The terminal device dynamically adjusts its synchronization behavior based on configuration parameters received from the network. When early downlink synchronization is configured, the terminal performs it before handover; otherwise, it performs synchronization after handover. This dynamic adaptation allows the system to optimize for low-latency services when needed while maintaining simplicity for other scenarios
Solution Approach 2:
The terminal device applies different synchronization strategies to different cells based on local conditions. For the target cell, it may perform early downlink synchronization to prepare for handover, while maintaining synchronization with the source cell until handover is complete. This localized approach allows simultaneous management of multiple synchronization states without overwhelming complexity
3Productivity
If the terminal device obtains TA information before handover, then data transmission can start immediately, but the network device needs to provide additional configuration information
Solution Approach 1:
The network device provides TA configuration information to the terminal device before handover occurs. This preliminary provision of configuration allows the terminal to calculate and apply TA values for the target cell in advance, enabling immediate uplink data transmission upon handover without waiting for post-handover configuration
Solution Approach 2:
The TA configuration information acts as an intermediary that bridges the network device and terminal device before handover. By providing this configuration information in advance, the network device enables the terminal to perform necessary calculations and preparations independently, reducing the need for complex real-time coordination during the handover process itself
Data Source
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AI summary
This application provides a communication method and a communication apparatus. The communication method may be applied to a terminal apparatus. The method includes: receiving first information, where the first information indicates a manner of obtaining a timing advance TA of a first cell; and obtaining the TA of the first cell based on the first information. According to the technical solution provided in this application, the obtaining manner of obtaining the TA of the first cell is configured for the terminal apparatus based on the first information. Therefore, before receiving a cell handover command, the terminal apparatus may obtain the TA of the first cell in the manner indicated by the first information, to complete uplink synchronization with the first cell. In this way, after the terminal apparatus is handed over to the first cell, the terminal apparatus may no longer perform the uplink synchronization process. Therefore, a handover delay of handover to the first cell can be reduced.