UE Idle-Period Channel Access Using gNB Clearance Indication
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Solution Overview
Problem
Current semi-static channel access procedures in 5G/NR-U systems impose restrictions on user equipment (UE) transmissions during idle periods, leading to reliability and latency degradation for URLLC/IIoT applications, particularly in unlicensed controlled environments.
Innovation Solution
Implement mechanisms for monitoring clearance indications from a base station to enable or disable UE communication during idle periods based on the base station's communication intentions, allowing UE-initiated COTs during gNB idle periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UE is restricted to transmit only within gNB-acquired COT, then gNB can control channel access and manage interference, but UE cannot perform transmissions on UL configured resources outside gNB-initiated COT, causing reliability and latency degradation
Solution Approach 1:
The patent introduces dynamic channel access behavior where UE can switch between two modes: (1) transmitting only within gNB-acquired COT (original restriction), and (2) transmitting during gNB idle period if UE detects channel is free. This dynamic adaptation allows UE to optimize between reliability (mode 1) and latency/flexibility (mode 2) based on channel conditions and traffic requirements, resolving the contradiction between transmission reliability and UE transmission flexibility
Solution Approach 2:
The patent changes the parameter of channel access restriction by introducing a new condition: UE can transmit during gNB idle period if LBT succeeds. This parameter change transforms the absolute restriction into a conditional permission, where the transmission behavior depends on channel sensing results. The gNB configures this behavior through RRC signaling, allowing flexible adjustment of the transmission parameter based on network conditions and service requirements
2Loss of time
If UE can initiate COT and transmit during gNB idle period, then UE communication flexibility and latency are improved, but gNB may experience unexpected interference from UE transmissions
Solution Approach 1:
The patent applies preliminary action by requiring UE to perform LBT (Listen Before Talk) before transmitting during gNB idle period. This preliminary channel sensing action ensures that UE only transmits when the channel is confirmed to be free, preventing interference to gNB. The LBT mechanism acts as a preventive measure that resolves the contradiction by eliminating the harmful interference issue before it can occur
Solution Approach 2:
The patent implements feedback through the LBT mechanism, where UE continuously monitors the channel status and adjusts its transmission behavior accordingly. If the channel is occupied, UE refrains from transmitting; if the channel is free, UE can transmit. This feedback-based control resolves the contradiction between improving latency and preventing interference to gNB
Data Source
AI summary
There are provided measures for enabling/realizing support for idle period communication in semi-static channel access. Such measures exemplarily comprise that a user equipment device monitors for presence of a clearance indication provided by a base station device serving the user equipment device, which indicates clearance for communication by the user equipment device in at least one idle period of abase station device frame period, disables communication by the user equipment device in the at least one idle period of the base station device frame period when the monitoring yields absence of the clearance indication, and enables communication by the user equipment device in the at least one idle period of the base station device frame period when the monitoring yields presence of the clearance indication.