Configurable Random Access Response Window Length for Unlicensed Spectrum
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Solution Overview
Problem
In unlicensed spectrum communications systems, setting an appropriate Random Access Response (RAR) window length is challenging due to limited frequency domain resources and interference from other systems, leading to reduced transmission success rates and increased delays during the random access process.
Innovation Solution
A method where the terminal device indicates the quantity of sending times of random access information to the network device, allowing the RAR window length to be configurable, enabling flexible adjustment based on different system requirements, and allowing the network device to send the RAR using varying window lengths to improve channel sensing opportunities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the RAR window length is fixed, then the system operation is simple, but the transmission success rate is reduced and delays increase due to LBT failures
Solution Approach 1:
The patent applies dynamics by making the RAR window length adjustable rather than fixed. The network device can dynamically configure different RAR window lengths based on channel conditions and LBT success rates, allowing the system to adapt to varying unlicensed spectrum environments and improve transmission reliability without excessive complexity
Solution Approach 2:
The patent changes the parameter of RAR window length from a fixed value to a configurable parameter. By allowing the network device to adjust this parameter based on actual channel conditions and LBT performance, the system can optimize transmission success rate while managing complexity through standardized adjustment mechanisms
2Reliability
If the RAR window length is extended to allow more LBT attempts, then the transmission success rate improves, but the random access delay increases
Solution Approach 1:
The patent uses dynamics by enabling the network device to adjust the RAR window length according to actual channel conditions. When channel conditions are good, a shorter window reduces delay; when conditions are poor, a longer window improves success rate, creating an adaptive balance between these conflicting objectives
Solution Approach 2:
The patent changes the RAR window length parameter based on LBT success rates and channel conditions. By dynamically adjusting this parameter, the system can optimize the trade-off between transmission success rate and access delay rather than being constrained by a fixed value
3Reliability
If the terminal device sends random access information multiple times, then the probability of receiving RAR improves, but the access delay increases
Solution Approach 1:
The patent applies feedback by using the LBT success rate as a basis for adjusting the RAR window length. The network device monitors channel access success and uses this feedback to optimize the window configuration, reducing unnecessary retransmissions and associated delays while maintaining reliable RAR reception
Data Source
AI summary
Embodiments of this application provide a random access method, a terminal device, and a network device. The method includes: A terminal device sends random access information to a network device. The random access information is used to indicate a quantity of sending times of the random access information sent by the terminal device to the network device; or the random access information is used to indicate a random access response window length corresponding to the random access information, and the random access response window length is configurable. The terminal device detects a random access response in a random access response window. According to the random access method, the terminal device, and the network device provided in the embodiments of this application, the random access response window length can flexibly vary with the quantity of sending times of the random access information, to meet requirements of different unlicensed spectrum systems.