NR-U CCA Failure Limits Adapted to Signal Periodicity
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Solution Overview
Problem
In NR-U networks, existing solutions for Clear Channel Assessment (CCA) failures use a fixed maximum allowed value (Lmax) regardless of signal periodicity, leading to suboptimal performance and degradation in operations like handover.
Innovation Solution
Adapting the maximum allowed CCA failures (Lmax) based on the operational occasion periodicity of signals such as SSB, PRACH, and CSI-RS, allowing UEs to perform specific tasks like restarting operations or declaring Radio Link Failure when the maximum is exceeded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed maximum allowed CCA failures value (Lmax) is used regardless of signal periodicity, then the system is simple to operate, but performance degrades in operations like handover and cell changes
Solution Approach 1:
The patent implements dynamic adaptation of Lmax based on operational occasion periodicity. The system transitions from a static fixed Lmax value to a dynamic value that changes according to the periodicity of signals like SSB, PRACH, and CSI-RS. This allows the CCA failure management to adapt to different operational scenarios, improving reliability in handover and cell changes while maintaining manageable complexity through standardized adaptation rules.
Solution Approach 2:
The patent changes the parameter Lmax based on the periodicity parameter of operational occasions. By establishing a relationship between Lmax and periodicity (e.g., longer periodicity leads to higher Lmax), the system optimizes performance for different signal types and operational scenarios. This parameter adaptation resolves the contradiction by allowing the system to adjust its behavior based on actual operational needs rather than using a one-size-fits-all approach.
2Reliability
If the maximum allowed CCA failures is adapted based on operational occasion periodicity, then performance in handover and cell changes is optimized, but the device complexity increases
Solution Approach 1:
The system implements dynamic Lmax adaptation that automatically adjusts based on the detected periodicity of operational occasions. The complexity is managed by using standardized periodicity values and corresponding Lmax mappings that are pre-defined or easily configurable, rather than requiring complex real-time calculations. This dynamic approach optimizes handover and cell change performance while keeping the adaptation mechanism relatively simple.
Solution Approach 2:
The patent establishes predetermined relationships between periodicity values and Lmax settings. By pre-defining these mappings, the system avoids complex real-time decision-making and instead uses lookup tables or simple comparison logic. This preliminary preparation of adaptation rules reduces the actual runtime complexity while maintaining optimized performance for different operational scenarios.
3Reliability
If Lmax is increased for low periodicity signals, then operations are prevented from premature termination, but the time for operational tasks increases
Solution Approach 1:
The patent changes Lmax based on periodicity to balance operation continuity and time efficiency. For low periodicity signals (e.g., 160ms), a higher Lmax is appropriate to prevent premature termination since opportunities are rare. For high periodicity signals (e.g., 10ms), a lower Lmax is used to allow faster operational completion. This parameter adaptation resolves the contradiction by matching Lmax to the inherent timing characteristics of each signal type.
Solution Approach 2:
The system dynamically adjusts Lmax according to the specific periodicity of each operational occasion type. This dynamic adjustment ensures that operations with longer intervals between opportunities (low periodicity) are given more tolerance for CCA failures, while operations with frequent opportunities (high periodicity) can complete faster with stricter failure limits. The dynamic nature of the adaptation allows the system to optimize for each specific operational context.
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.