NR-U CCA Failure Limits Adapted to Operational Periodicity
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Solution Overview
Problem
In NR-U networks, the existing solution for maximum allowed Clear Channel Assessment (CCA) failures is not optimized based on the configurable parameters of operational occasions, leading to performance degradation in vital operations such as handover.
Innovation Solution
A wireless device determines the operational occasion periodicity and associates it with a maximum number of allowed CCA failures to adapt communication strategies, including restarting operations, declaring Radio Link Failure, or triggering cell changes if failures exceed the determined limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed maximum number of CCA failures is used for all operational occasions, then the configuration is simple, but performance degradation occurs in vital operations such as handover
Solution Approach 1:
The patent applies dynamics by making the maximum CCA failure limit adaptive rather than fixed. The limit is dynamically adjusted based on the periodicity of operational occasions - operations with longer periodicity are allocated higher failure limits while frequent operations receive lower limits. This dynamic adaptation resolves the contradiction by optimizing reliability for each operation type without requiring complex manual configuration.
Solution Approach 2:
The patent changes the parameter of maximum CCA failure limit based on operational periodicity. By establishing a relationship between the periodicity parameter and the failure limit parameter, the system automatically adjusts the failure threshold according to the operational characteristics. This parameter change approach maintains simple configuration while improving operation performance.
2Reliability
If the maximum CCA failure limit is increased for frequent operations, then more transmission attempts are allowed, but this causes unnecessary delays and resource waste
Solution Approach 1:
The patent applies local quality by assigning different maximum CCA failure limits to different operational occasions based on their specific periodicity characteristics. Frequent operations (short periodicity) receive lower failure limits to minimize delay, while less frequent operations (long periodicity) receive higher limits to ensure reliability. This localized optimization resolves the contradiction by tailoring the failure limit to each operation's needs rather than applying a uniform limit.
3Loss of time
If the maximum CCA failure limit is decreased for infrequent operations, then transmission delay is reduced, but transmission success rate drops due to insufficient retry opportunities
Solution Approach 1:
The patent changes the maximum CCA failure limit parameter according to the periodicity of operational occasions. For infrequent operations with long periodicity, the system allocates higher failure limits, providing sufficient retry opportunities to maintain transmission success rate. This parameter adaptation resolves the contradiction by ensuring that each operation type receives an appropriate failure limit matched to its frequency characteristics.
4Ease of operation
If a uniform CCA failure limit is applied to all PRACH occasions, then configuration is straightforward, but handover performance deteriorates
Solution Approach 1:
The patent applies dynamics by implementing adaptive CCA failure limits for PRACH occasions based on their periodicity. Handover-related PRACH occasions with longer periodicity automatically receive higher failure limits, while other PRACH occasions use lower limits. This dynamic approach maintains configuration simplicity through automated adaptation while significantly improving handover performance.
Data Source
AI summary
Methods performed by a wireless device and a base station for adapting maximum allowed Clear Channel Assessment (CCA) based on operational occasion periodicity are provided. In examples disclosed herein, a wireless device is configured to determine an operational occasion periodicity of a signal that is subject to CCA. Accordingly, the wireless device can determine an association at least between the determined operational occasion periodicity and a maximum number of allowed CCA failures for communicating the signal. The wireless device can then perform one or more operational tasks based on the determined maximum number of allowed CCA failures. By determining the maximum number of allowed CCA failures, the wireless device can obtain information about downlink CCA failures and use the obtained information for adapting measurements procedures in serving cell operational tasks.