PRACH Channel Sensing With COT Sharing in NR-U Random Access
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Solution Overview
Problem
The challenge of efficiently utilizing the unlicensed spectrum for channel occupancy time (COT) sharing in new radio (NR) systems to enhance bandwidth, latency, and data rates is hindered by the need for effective coexistence with other radio access technologies (RATs, such as Wi-Fi) and the limitations of existing channel access mechanisms.
Innovation Solution
Implementing channel sensing and COT sharing for physical random access channel (PRACH) signals in NR-U, allowing gNB and UE to initiate COT sharing in a random access procedure, with specific message gaps and hybrid automatic repeat request (HARQ) feedback within the same COT to optimize channel usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If channel sensing and COT sharing are implemented for PRACH signals in NR-U, then bandwidth utilization and data rates are enhanced, but coexistence with other RATs becomes more complex
Solution Approach 1:
The patent segments the unlicensed spectrum channel access into distinct phases: initial channel sensing, COT acquisition, and COT sharing. By dividing the random access procedure into separate message stages (Msg1, Msg2, Msg3, Msg4) that can independently share COT, the system enhances bandwidth utilization while managing coexistence complexity through structured segmentation of channel access operations
Solution Approach 2:
The patent implements dynamic COT sharing mechanisms where the gNB and UE can flexibly allocate and share channel occupancy time based on real-time channel conditions and service requirements. The dynamic adjustment of COT parameters and the flexible message timing within shared COT enable adaptive bandwidth utilization while maintaining coordinated operation with other RATs
2Loss of time
If COT sharing is enabled for random access messages, then latency is reduced, but channel access coordination becomes more difficult
Solution Approach 1:
The patent applies preliminary action by having the gNB perform channel sensing and acquire COT before initiating the random access procedure. The gNB pre-configures the UE with COT sharing parameters and timing information in advance, allowing subsequent messages (Msg2, Msg3, Msg4) to be transmitted within the pre-acquired COT without requiring additional channel access coordination, thereby reducing latency while simplifying operational complexity
Solution Approach 2:
The patent implements feedback mechanisms where the gNB monitors channel conditions and COT usage throughout the random access procedure, adjusting message timing and resource allocation based on real-time feedback. The UE provides feedback on channel quality and reception status, enabling the gNB to optimize COT sharing parameters and maintain efficient channel access coordination with minimal complexity
3Reliability
If channel sensing is performed for PRACH signals, then coexistence with Wi-Fi and other RATs is improved, but channel access time increases
Solution Approach 1:
The patent ensures continuity of useful action by implementing channel sensing and COT acquisition at the beginning of the random access procedure, then maintaining continuous channel occupancy for subsequent messages without requiring repeated sensing operations. The gNB acquires COT once and shares it continuously across multiple random access messages, ensuring reliable coexistence with Wi-Fi and other RATs while minimizing total channel access time through uninterrupted transmission within the shared COT
Data Source
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AI summary
A user equipment (UE), or other network component can operate to configure channel occupancy time (COT) sharing in random access procedures involving the unlicensed spectrum. At least some of the messages for the procedures can share a COT by configuring one or more gaps or listen-before-talk (LBT) procedures based on the gap or whether the COT sharing is UE or gNB initiated. Some configurations can depend on a location in the random access procedure that COT sharing is acquired.