PRACH Channel Access Switching for Fair NR-U Spectrum Sharing
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Solution Overview
Problem
Existing technologies lack effective solutions for channel access in the unlicensed spectrum, particularly for new radio-unlicensed (NR-U) systems, which support standalone scenarios requiring both contention-based and contention-free random access channels, leading to inefficiencies in channel access and fairness of spectrum utilization.
Innovation Solution
A method and apparatus for determining the target channel access type, including type1 and type2 channel access types, to ensure availability of time domain resources for PRACH transmission, ensuring fairness and transmission performance by employing channel detection based on priority, directionality, and shared channel occupancy times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If channel access detection is performed before PRACH transmission on unlicensed spectrum, then fair spectrum sharing is achieved, but transmission delay increases and access efficiency deteriorates
Solution Approach 1:
The network device pre-configures channel access parameters including channel access priority, contention window size, and minimum channel occupancy time before the random access procedure. The terminal device uses these pre-configured parameters to perform channel access detection, eliminating the need for real-time parameter negotiation and reducing access delay while ensuring fair spectrum sharing through prioritized access mechanisms
Solution Approach 2:
The patent implements dynamic channel access parameters that can be adjusted based on traffic conditions and priority levels. Different channel access priorities (1-8) correspond to different contention window sizes and minimum occupancy times, allowing high-priority traffic to access the channel faster while low-priority traffic uses longer occupancy times to ensure fair sharing. This parameter adaptation resolves the contradiction between fast access and fair sharing
2Reliability
If channel occupancy time is extended to ensure complete data transmission, then transmission reliability improves, but spectrum utilization efficiency deteriorates
Solution Approach 1:
The channel occupancy time is made dynamic rather than fixed. The minimum channel occupancy time parameter can be adjusted based on the amount of data to be transmitted, channel conditions, and priority level. This allows the system to use shorter occupancy times when possible (improving spectrum utilization) while ensuring sufficient time for complete transmission when needed (maintaining reliability), thus resolving the contradiction between these two objectives
3Reliability
If channel access priority is reduced to ensure fair spectrum sharing, then spectrum fairness improves, but access speed deteriorates
Solution Approach 1:
Different channel access priorities are assigned to different types of traffic or terminal devices based on their specific requirements. High-priority traffic (e.g., emergency communications, real-time control) uses priority levels 1-4 with shorter contention windows and faster access, while low-priority traffic (e.g., background data, non-real-time applications) uses priority levels 5-8 with longer contention windows. This localized quality assignment allows each traffic type to achieve its optimal access speed while the overall system maintains fairness through the priority differentiation mechanism
Data Source
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AI summary
This application discloses a channel access method and apparatus for physical random access channel (PRACH) transmission. The method includes: determining (201), by a terminal device according to a type1 channel access type, an availability of a target time domain resource, wherein the target time domain resource is a time domain resource used by the terminal device to perform transmission of a physical random access channel (PRACH); determining (202), by the terminal device, whether the target time domain resource belongs to a shared channel occupancy time; if the target time domain resource belongs to a shared channel occupancy time, using, by the terminal, a type2 channel access type; and if the target time domain resource does not belong to a shared channel occupancy time, using, by the terminal, the type1 channel access type.