Timing Advance Determination for Random Access Delay Reduction
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Solution Overview
Problem
The existing random access process in communications technologies experiences a significant delay between the second and third messages (Msg2 and Msg3) due to the use of a large timing advance (TA) calculated based on a maximum cell radius of 300 km, which reduces the efficiency of the random access process.
Innovation Solution
The proposed method involves determining a timing advance (TA) based on the actual cell radius supported by the random access preamble format, a subcarrier spacing, and other parameters, allowing for flexible TA determination and reduction, thereby minimizing the time gap between Msg2 and Msg3. This is achieved by the terminal or network device calculating or receiving a TA value that is specific to the terminal's capabilities and the cell coverage, rather than relying on a fixed maximum value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a fixed maximum timing advance (TA) value is used for all terminals, then the coverage area can support the maximum cell radius of 300 km, but the time gap between Msg2 and Msg3 becomes unnecessarily large, reducing random access efficiency
Solution Approach 1:
The patent applies local quality by determining different TA values for different terminals based on their specific conditions. Instead of using a uniform maximum TA value for all terminals, the network device calculates and notifies each terminal of its specific TA value based on the terminal's distance from the network device and the supported cell radius. This allows terminals in different locations within the cell to use appropriately sized TA values, reducing the time gap for nearby terminals while maintaining sufficient coverage for distant terminals.
Solution Approach 2:
The patent implements dynamics by making the TA value adaptable rather than fixed. The TA value is dynamically determined based on the terminal's specific scenario, including its distance from the network device and the cell radius supported by the random access preamble format. The network device can notify different TA values to different terminals, allowing the system to optimize the time gap for each terminal's actual conditions rather than using a static maximum value for all.
2Loss of time
If a TA value is determined based on actual cell radius and terminal-specific parameters, then the time gap between Msg2 and Msg3 is reduced, but the complexity of TA determination increases
Solution Approach 1:
The patent applies self-service by enabling the network device to automatically determine and notify appropriate TA values to terminals based on pre-established relationships between random access preamble formats and supported cell radii. The system maintains correspondence relationships between different preamble formats and their supported maximum cell radii, allowing the network device to automatically select appropriate TA values without complex real-time calculations, thereby reducing the perceived complexity for terminals while achieving optimized TA values.
Solution Approach 2:
The patent implements preliminary action by pre-establishing correspondence relationships between random access preamble formats and their supported maximum cell radii. These relationships are determined in advance and stored in the network device, allowing for quick TA value determination during the random access process. The network device can directly lookup and notify the appropriate TA value based on the terminal's selected preamble format, avoiding complex real-time calculations and reducing both computational complexity and processing time.
Data Source
AI summary
This application discloses a delay reduction method and apparatus, applied to a random access process. The method includes: sending, by a terminal device, a message 1 to a network device, where the message 1 is a random access preamble; receiving, by the terminal device, a message 2 sent by the network device; and sending, by the terminal device, a message 3 to the network device, where a time gap between receiving the message 2 and sending the message 3 is set by the terminal based on a timing advance (TA) value. In an embodiment, the TA value is related to a message 1 format of the terminal device and a cell radius or subcarrier spacing supported by the message 1. In this solution, a TA value is reduced, and random access efficiency is improved.