Uplink Transmission in NR Unlicensed Spectrum via COT Gap Sensing
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing uplink transmissions in frame-based equipment for New Radio (NR) unlicensed spectrum, particularly in shared spectrum channel access, where existing methods do not effectively optimize channel occupancy time (COT) for reducing power consumption and improving spectrum utilization.
Innovation Solution
The implementation of a user equipment (UE) and base station (BS) configuration that determines and utilizes a channel occupancy time (COT) with a gap between downlink and uplink portions, allowing for a channel access procedure based on the duration of this gap to ensure efficient uplink transmission in idle shared spectrum channels, thereby optimizing power usage and spectrum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the UE continuously monitors the shared spectrum channel for uplink transmission opportunities, then the uplink transmission responsiveness is improved, but the power consumption increases
Solution Approach 1:
The base station performs preliminary channel access and secures a Channel Occupancy Time (COT) before the UE needs to transmit. The BS announces this pre-acquired COT information to the UE, allowing the UE to wait for the predetermined uplink transmission opportunity within the COT without needing to continuously monitor or perform its own channel access, thus reducing power consumption while maintaining transmission responsiveness.
2Productivity
If the BS allocates continuous COT for downlink and uplink transmissions, then the spectrum utilization is improved, but the channel access reliability deteriorates due to lack of idle sensing
Solution Approach 1:
The COT is segmented into multiple portions with a gap between the downlink portion and uplink portion. This segmentation allows the channel to be sensed as idle during the gap, ensuring reliable channel access verification while still maintaining high spectrum utilization by having predetermined transmission opportunities for both downlink and uplink within the same COT.
3Reliability
If the UE performs channel access procedure continuously, then the channel access reliability is improved, but the transmission efficiency decreases
Solution Approach 1:
The base station performs the channel access procedure in advance and announces the COT information to the UE. This preliminary action allows the UE to skip continuous channel access procedures and simply wait for the predetermined uplink transmission opportunity within the announced COT, thereby maintaining channel access reliability while significantly improving transmission efficiency.
4Measurement precision
If the gap duration between downlink and uplink portions is extended, then the channel sensing accuracy is improved, but the time available for transmission decreases
Solution Approach 1:
The gap duration is set to the minimum necessary length to perform idle channel sensing (partial action), rather than extending it to maximize sensing accuracy. This approach provides sufficient channel sensing accuracy to ensure reliable access while preserving maximum transmission duration within the COT, achieving an optimal balance between sensing accuracy and transmission efficiency.
Data Source
AI summary
Methods and apparatuses of a BSs and UEs in a wireless communication system are provided. A method of operating the UE comprises: receiving, from a BS over a shared spectrum channel, a first DCI including a COT of the BS; determining a first portion of the COT for a downlink transmission from the BS and a second portion of the COT for an uplink transmission to the BS, wherein the COT includes a gap between the first and second portions of the COT; performing a channel access procedure based on a duration of the gap; receiving the downlink transmission in the first portion of the COT; and transmitting the uplink transmission in the second portion of the COT based on a sensing status of the shared spectrum channel that is sensed as an idle state during the channel access procedure in the duration of the gap.