Random Access Timing Offsets for High-Delay Uplink Synchronization
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Solution Overview
Problem
In long-distance and high delay scenarios, such as satellite communications, terminal devices face challenges in accessing a mobile communications system due to high transmission delays, leading to random access failures as they cannot receive a random access response (RAR) within the monitoring window.
Innovation Solution
The method involves using offset information in a first message to adjust the RAR monitoring window and the timing of subsequent messages, allowing the terminal device to synchronize with the network by indicating time offset values for RAR monitoring and message transmission, thereby improving access success in high delay scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal device uses a fixed RAR monitoring window in the random access process, then the system maintains simple timing structure, but the terminal device cannot receive RAR in long-distance transmission scenarios with high delay
Solution Approach 1:
The patent applies dynamics by making the RAR monitoring window configurable through offset information. The network device can dynamically adjust the monitoring window position and duration based on transmission delay characteristics, allowing the system to adapt to both long-distance satellite communication and terrestrial cellular scenarios without increasing fundamental system complexity
Solution Approach 2:
The patent changes the timing parameters of the RAR monitoring window by introducing offset information (k1, k2, k3) that define the window's position relative to the random access preamble. This parameter adjustment enables the system to accommodate varying transmission delays while maintaining a consistent random access procedure framework
2Loss of time
If the network device sends RAR immediately after receiving the random access preamble, then the transmission delay is minimized, but the terminal device may not have completed uplink timing alignment in long-distance scenarios
Solution Approach 1:
The patent applies preliminary action by having the terminal device perform uplink timing alignment before sending the random access preamble. The network device then uses the measured timing information to determine appropriate offset values for the RAR monitoring window, ensuring that subsequent uplink transmissions are properly synchronized even in long-distance scenarios
Solution Approach 2:
The patent implements feedback by having the network device measure the timing of the received random access preamble and use this information to calculate offset values. This feedback loop allows the system to adapt the RAR timing to the actual transmission conditions, ensuring reliable uplink synchronization
3Reliability
If the RAR monitoring window is extended to accommodate high delay scenarios, then the terminal device can receive RAR successfully, but the system resource utilization decreases
Solution Approach 1:
The patent applies local quality by configuring different RAR monitoring window parameters for different scenarios. The network device can set specific offset values and window durations tailored to the transmission characteristics of each terminal device, whether in satellite or terrestrial communication, rather than using a uniform configuration for all devices
4Adaptability or versatility
If the terminal device waits for RAR before sending the second message, then the random access procedure follows standard protocol, but the timing advance mechanism cannot be applied in long-distance scenarios
Solution Approach 1:
The patent changes the timing parameters for sending the second message by introducing offset information that is conditioned on RAR reception. The terminal device uses the offset values (k1, k2, k3) to calculate the appropriate timing for the second message, allowing the timing advance mechanism to function in long-distance scenarios while maintaining protocol compatibility
Data Source
AI summary
An example communications method is provided. A terminal device starts to send the uplink data at a second start time of sending the uplink data, wherein the second start time of sending the uplink data is after a second time interval plus the time offset value for sending the uplink data, and the second time interval is a time-domain interval between a time of receiving the resource scheduling indication information and a first start time of sending the uplink data.