DL/UL Switching Point Control in NR Unlicensed Spectrum
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Solution Overview
Problem
The challenge in Next Generation Radio (NR) systems operating in unlicensed spectrum, such as the 5 GHz band, is maintaining fair coexistence with other technologies, particularly in managing downlink-to-uplink (DL/UL) and uplink-to-downlink switching points within a shared channel occupancy time (COT), where interference levels vary, affecting channel acquisition and leading to increased probability of errors and listen before talk (LBT) failures.
Innovation Solution
The solution involves controlling the number of DL/UL switching points in a shared COT by acquiring a shared channel occupancy time that includes DL and UL bursts, utilizing these bursts as reference bursts to derive a metric based on HARQ-ACK feedback or success/failure status, and comparing this metric to threshold values to adjust the number of switching points, thereby optimizing switching points independently or jointly with contention window size (CWS) adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of DL/UL switching points is increased to improve resource utilization flexibility, then system adaptability improves, but interference levels increase and LBT failure probability increases
Solution Approach 1:
The patent applies dynamics by making the number of DL/UL switching points adjustable rather than fixed. The gNB dynamically controls the quantity of switching points within the COT based on current channel conditions and interference levels, allowing the system to adapt between flexibility and reliability needs. This is implemented through RRC configuration messages that specify the number of switching points, enabling real-time optimization without fixed constraints.
Solution Approach 2:
The patent changes the parameter of switching point quantity based on channel conditions. By monitoring channel occupancy time and interference characteristics, the system adjusts the number of DL/UL switching points as a controllable parameter. This parameter change allows optimization of resource utilization while maintaining LBT success rates by reducing switching points when interference is high.
2Productivity
If DL/UL switching points are added to improve channel access efficiency, then productivity improves, but channel acquisition difficulty increases due to varying interference levels
Solution Approach 1:
The patent applies preliminary action by performing LBT procedures and determining channel availability before initiating DL or UL transmissions at switching points. The gNB performs channel sensing and acquires the COT in advance, then plans the sequence of DL and UL bursts within this acquired time window. This preliminary channel acquisition ensures that subsequent switching operations occur on validated channels, reducing acquisition difficulty while maintaining efficiency.
Solution Approach 2:
The system uses feedback from LBT outcomes and channel condition measurements to adjust channel access strategies. The gNB monitors LBT success/failure rates and channel occupancy patterns, then uses this feedback to optimize the number and timing of DL/UL switching points. This closed-loop approach improves channel access efficiency while adapting to varying interference conditions that affect acquisition difficulty.
3Productivity
If the number of DL/UL switching points is increased to improve data transmission capacity, then productivity improves, but error probability increases due to interference
Solution Approach 1:
The patent segments the channel occupancy time into distinct DL bursts and UL bursts separated by controlled switching points. By dividing the transmission timeline into manageable segments with clear boundaries, the system can optimize each segment independently while maintaining overall capacity. The segmentation approach reduces error propagation between bursts and allows targeted error handling for each PDSCH/PUSCH transmission.
Solution Approach 2:
The patent applies partial action by using a limited, optimized number of DL/UL switching points rather than maximizing them. The system determines the optimal quantity of switching points that provides sufficient data transmission capacity while staying below the threshold where interference-induced errors increase. This partial approach balances productivity and reliability by avoiding excessive switching that would degrade reception success rates.
Data Source
AI summary
The present disclosure is directed to systems and methods for controlling a number of allowed downlink/uplink (DL/UL) switching points. For example, the method may include acquiring a shared channel occupancy time (COT) that includes one or more DL bursts and/or UL bursts. The method may also include utilizing one or more of the DL bursts or the UL bursts as a reference burst. The method may also include deriving a metric for controlling the number of DL/UL switching points in the shared COT based on the reference burst. The method may also include comparing the metric to a threshold value. The method may also include setting the number of DL/UL switching points in the shared COT based on the comparison of the metric to the threshold value.