NTN Handover Requests Using TA and Trajectory for Uplink Timing
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Solution Overview
Problem
In Non Terrestrial Network (NTN) systems, the large coverage of satellites results in varying wireless signal transmission delays among terminal devices and satellites, leading to potential uplink resource misalignment and increased handover delays due to improper scheduling of uplink transmissions.
Innovation Solution
A communication method involving network devices exchanging handover requests that include Timing Advance (TA) or location and movement trajectory information to determine optimal uplink resource allocation, ensuring the uplink transmission time is after downlink reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the target base station schedules the uplink transmission based on a delay value less than the real round-trip delay, then the scheduling efficiency is improved, but the uplink resource may be allocated before the actual reception time causing the terminal device to miss the resource
Solution Approach 1:
The patent applies preliminary action by having the terminal device perform Timing Advance (TA) measurement before handover and report it to the target base station in advance. This allows the target base station to pre-calculate the correct uplink transmission time based on the reported TA value, ensuring that the uplink resource is scheduled at the appropriate time without causing the resource to be missed while maintaining efficient scheduling.
2Reliability
If the target base station schedules the uplink transmission based on the maximum round-trip delay within the cell coverage, then the uplink resource availability is ensured, but the uplink transmission delay increases causing increased handover delay
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the uplink transmission time parameter based on the actual TA measurement value reported by the terminal device. Instead of using a fixed maximum round-trip delay for all terminals, the system calculates the specific uplink transmission time for each terminal based on its measured TA, thereby ensuring uplink resource availability while minimizing handover delay for each individual terminal.
3Measurement precision
If the handover request includes TA measurement information, then the uplink resource scheduling accuracy is improved, but the signaling overhead between network devices increases
Solution Approach 1:
The patent applies the extraction principle by isolating the TA measurement information into a dedicated field within the handover request message. This allows the target base station to extract and process only the necessary TA value for uplink scheduling without being burdened by unnecessary signaling data, thereby improving scheduling accuracy while minimizing the impact of signaling overhead on the overall system.
Data Source
AI summary
The present disclosure provides a communication method and apparatus, the method includes: sending, by a first network device, a handover request to a second network device, where the handover request is used for handing over a target network device that serves a terminal device from the first network device to a second network device, and the handover request includes a TA of the terminal device with the second network device, or includes location information of the terminal device and a movement trajectory of the terminal device for determining the TA of the terminal device with the second network device. In this way, as the second network device after handover has determined the timing advance TA of the terminal device with the second network device, an uplink transmission time indicated by the network device can be prevented from being before a downlink reception time, ensuring usability of uplink resource configuration.