Radio Unit Clear Channel Assessment via Candidate Detection
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Solution Overview
Problem
The existing Clear Channel Assessment (CCA) process in Licensed Assisted Access (LAA)-LTE systems experiences significant delays due to CCA failures, particularly when there is a large distance between the Digital Unit (DU) and the Radio Unit (RU), which degrades system performance by reducing the ability to seize unlicensed channels in competing with other co-existing systems.
Innovation Solution
A method and apparatus for the Radio Unit (RU) that detects unoccupied candidate channels during a first transmission period and determines their availability during a second transmission period, allowing for the selection of a clear channel without reporting failures to the DU, thereby reducing overall delay and improving channel seizure capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the RU reports CCA failure to the DU and waits for new channel indication, then the channel selection process follows the standardized procedure, but the transmission delay increases significantly
Solution Approach 1:
The RU performs preliminary detection of candidate channels during the first transmission period before the CCA failure occurs. By proactively identifying potential clear channels in advance, the RU prepares alternative transmission options so that when CCA fails on the current channel, it can immediately switch to a pre-identified clear channel without waiting for DU reselection, thus resolving the contradiction between reliable failure handling and minimizing delay
Solution Approach 2:
The RU autonomously selects a clear candidate channel from its own detected unoccupied channels when the current channel becomes unavailable, without requiring DU intervention for channel reselection. This self-service capability allows the RU to independently resolve CCA failures, maintaining reliability while eliminating the time-consuming round-trip communication with the DU
2Productivity
If the RU autonomously selects clear candidate channels without DU intervention, then the channel acquisition speed improves, but the system complexity increases
Solution Approach 1:
The channel management functionality is segmented between the DU (which maintains overall control and receives final channel reports) and the RU (which performs autonomous candidate detection and selection). The RU's autonomy is limited to monitoring specific candidate channels and selecting from pre-identified options, rather than implementing full channel management complexity, thus improving acquisition speed while controlling device complexity
Solution Approach 2:
The patent introduces an intermediary mechanism where the RU autonomously manages candidate channel detection and selection, acting as a mediator between the DU's channel allocation decisions and the actual transmission requirements. This intermediary layer at the RU handles the complexity of real-time channel assessment locally, improving speed while keeping the overall system architecture manageable through clear division of responsibilities
Data Source
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AI summary
The present disclosure provides a method (300) in a Radio Unit (RU) for facilitating Clear Channel Assessment (CCA). The method (300) comprises: detecting (S310), in a first transmission period while the RU is operating in a first channel, whether one or more candidate channels in proximity to the first channel are unoccupied; determining (S320), when the first channel is not clear for transmission in a second transmission period, whether any of the one or more candidate channels that is detected to be unoccupied is clear for transmission in the second transmission period; and selecting (S330) one of the one or more candidate channels that is determined to be clear, for transmission in the second transmission period.