Satellite Random Access Parameter Adjustment for Latency
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Solution Overview
Problem
The existing 5G new radio (NR) protocol for satellite communication faces challenges in random access due to high transmission latency, causing failures in receiving the random access response (RAR) within the specified window, especially for user equipment (UE) at the edge of satellite coverage.
Innovation Solution
A method and apparatus that adjust random access parameters such as tX, tY, tbackoff, and tsubframe based on the round-trip transmission latency between the UE and the satellite, ensuring the RAR arrives within the reception window, thereby improving the success rate of random access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the existing 5G NR protocol is directly used in satellite communication, then the protocol structure is simple and easy to implement, but the random access fails because UE at the edge of satellite coverage area cannot receive the Msg 2 within the specified window due to high transmission latency
Solution Approach 1:
The patent applies dynamics by making the random access parameters (tX, tY, tbackoff, tsubframe) adjustable and adaptable to different satellite communication scenarios. Instead of using fixed protocol parameters, the system dynamically determines appropriate parameter values based on the specific satellite orbit, coverage area, and signal propagation conditions, allowing the random access procedure to adapt to varying latency conditions across different coverage zones
Solution Approach 2:
The patent directly applies parameter changes by modifying the random access parameters tX, tY, tbackoff, and tsubframe to suit satellite communication requirements. The method calculates and sets these parameters based on the round-trip transmission latency characteristics of satellite channels, thereby resolving the contradiction between fixed protocol specifications and variable satellite propagation delays
2Reliability
If the random access window duration is extended to accommodate high latency, then the random access success rate improves, but the time resource occupation increases and system efficiency decreases
Solution Approach 1:
The patent applies local quality by differentiating the random access parameters for different regions within the satellite coverage area. UEs at the edge of coverage, which experience higher latency, are allocated different parameter values compared to UEs in the center of coverage. This localized parameter optimization ensures reliable RAR reception for edge UEs while minimizing time resource occupation for other UEs, thereby maintaining overall system efficiency
3Reliability
If the random access parameters are optimized for edge UEs, then the random access success rate at coverage edge improves, but the complexity of parameter configuration and management increases
Solution Approach 1:
The patent applies self-service by enabling UEs to autonomously determine their own random access parameters based on their location within the satellite coverage area and the broadcast system information. Instead of requiring complex network-side configuration and management of different parameter sets, each UE independently selects appropriate parameters according to pre-defined rules and its own measurement results, significantly reducing the complexity of parameter configuration and management
Data Source
AI summary
This application provides a random access method and apparatus applicable to satellite communication. The method includes: obtaining a round-trip transmission latency tRTD of a signal between a terminal device and a satellite; obtaining a random access parameter based on the tRTD, where the random access parameter includes one or more of: a duration between a moment at which the terminal device sends a random access preamble and a moment at which the terminal device starts to receive a random access response RAR, a duration of a window in which the terminal device receives the RAR, a duration between a moment at which the terminal device stops receiving the RAR and a moment at which the terminal device sends the random access preamble again, and a subframe duration; and receiving, by the terminal device the RAR based on the random access parameter.