Adaptive LBT Mechanism for Unlicensed Spectrum Channel Access
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Solution Overview
Problem
Current channel access mechanisms for Random Access (RA) and Physical Uplink Control Channel (PUCCH) in unlicensed spectrum face challenges such as increased latency due to channel uncertainty and inefficient resource usage, particularly in scenarios with varying channel occupancy and Quality of Service (QoS) requirements, where existing methods lack flexibility and adaptability.
Innovation Solution
An enhanced channel sensing mechanism is proposed that selects a channel sensing procedure based on the purpose of transmission, channel occupancy, and latency metrics, allowing for adaptive configuration of Listen-Before-Talk (LBT) schemes to optimize channel access and reduce unnecessary operations, enabling flexible signaling and resource allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Listen-Before-Talk (LBT) channel sensing procedure is performed for every transmission in unlicensed spectrum, then channel access reliability is improved, but transmission latency increases due to channel uncertainty and repeated sensing operations
Solution Approach 1:
The patent combines multiple transmissions (RA procedure transmissions and PUCCH transmissions) into a single channel occupancy period. Once a UE successfully senses the channel and gains access, it can perform multiple subsequent transmissions without performing LBT again, as long as they occur within the same channel occupancy period. This merging of multiple transmission opportunities into one continuous occupancy period reduces the number of repeated LBT operations and associated latency.
Solution Approach 2:
The patent establishes a channel occupancy period through preliminary LBT sensing action. Once the channel is successfully accessed and the occupancy period is established, this preliminary action enables subsequent transmissions to proceed without repeating the LBT process. The initial channel sensing and occupancy establishment serves as a preliminary action that benefits multiple future transmissions within that occupancy window.
2Reliability
If LBT operations are performed frequently to ensure channel access, then channel access success rate is improved, but signaling overhead and resource waste increase
Solution Approach 1:
The patent merges multiple transmission types (RA and PUCCH) into a single channel occupancy framework. By combining these transmissions under one LBT operation and one channel occupancy period, the system avoids the signaling overhead that would result from separate LBT procedures and separate occupancy management for each transmission type.
Solution Approach 2:
The channel occupancy period serves multiple functions simultaneously - it enables both RA transmissions and PUCCH transmissions without requiring separate LBT operations. This multi-functionality of the channel occupancy mechanism reduces signaling overhead by using a universal access framework rather than separate procedures for different transmission types.
3Reliability
If channel sensing is performed for each transmission type independently, then transmission reliability is improved, but resource usage efficiency deteriorates
Solution Approach 1:
The patent merges RA transmissions and PUCCH transmissions into a unified channel occupancy period. This combining allows multiple transmission types to share the same channel access opportunity and occupancy window, improving resource usage efficiency by eliminating redundant sensing operations while maintaining transmission reliability through the initial thorough LBT procedure.
Data Source
AI summary
A method performed by a wireless device (110) includes, for a first transmission of a procedure, selecting a first channel sensing procedure for determining availability of a channel in the unlicensed spectrum. Based on the first channel sensing procedure, it is determined that the channel in the unlicensed spectrum is available. In response to determining that the channel in the unlicensed spectrum is available, a maximum channel occupancy time, MCOT, duration associated with the first channel sensing procedure is determined. The MCOT duration is an amount of time in which the wireless device and a network node are allowed to transmit on the channel in the unlicensed spectrum for the procedure. The wireless device transmits the first transmission during the MCOT duration and receives a second transmission from a network node (160). The second transmission includes a first listen-before-talk, LBT, scheme for a third transmission associated with the procedure.