Sidelink Channel Access Reservation in Unlicensed Spectrum
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Solution Overview
Problem
Sidelink communications in unlicensed spectrum face challenges with channel access due to sharing frequency spectrum with other technologies and channel sensing regulations, leading to difficulties in resource reservation and utilization.
Innovation Solution
A method and system for efficient channel access in unlicensed spectrum, where user equipment (UE) reserves time-frequency resources for sidelink transmissions by transmitting a message indicating reserved slots, and communicates based on control messages, RSRP measurements, and channel sensing procedures, allowing multiple UEs to share channel occupancy time without continuous sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a UE performs continuous channel sensing before each reserved resource in unlicensed spectrum, then channel access reliability is improved, but channel access efficiency and resource utilization deteriorate due to increased sensing overhead and potential loss of reserved resources
Solution Approach 1:
The UE performs channel sensing in advance at a first reserved resource and determines channel accessibility before the second reserved resource is needed. This preliminary sensing action allows the UE to secure channel access rights early, ensuring reliable access at the second resource without performing redundant sensing operations, thus resolving the contradiction between reliability and efficiency
Solution Approach 2:
The patent extracts the channel sensing operation from being required at every reserved resource and applies it only at the first reserved resource. This selective approach removes unnecessary sensing overhead while maintaining access reliability, directly addressing the efficiency deterioration caused by continuous sensing
2Reliability
If a UE monitors continuous sidelink transmission with small gap values to verify channel accessibility, then resource reservation reliability is improved, but time utilization and communication efficiency deteriorate due to frequent monitoring interruptions
Solution Approach 1:
The UE performs channel sensing and determines accessibility in advance at the first reserved resource before the second reserved resource is needed. This preliminary determination eliminates the need for continuous monitoring with small gaps, maintaining reservation reliability while significantly improving time utilization by removing monitoring interruptions
Solution Approach 2:
Instead of monitoring every reserved resource with small gap values, the patent applies monitoring only where necessary (at the first resource) and trusts the preliminary determination for subsequent resources. This partial action approach maintains sufficient reliability while reducing time loss from frequent monitoring
3Productivity
If multiple UEs share channel occupancy time in unlicensed spectrum, then spectrum utilization is improved, but channel access complexity increases due to coordination overhead and collision risks
Solution Approach 1:
The patent segments the channel occupancy time into distinct reserved resources with specific sensing requirements. The first reserved resource requires channel sensing while subsequent resources rely on preliminary determination. This segmentation allows multiple UEs to share spectrum efficiently while reducing individual UE complexity by clearly defining when sensing is needed
Solution Approach 2:
By performing channel sensing and accessibility determination at the first reserved resource in advance, the patent reduces coordination overhead for subsequent resources. This preliminary action simplifies the access protocol for multiple UEs sharing the channel, maintaining high spectrum utilization while reducing the complexity of continuous coordination
Data Source
AI summary
Methods, systems, and devices for wireless communications are described in which a user equipment (UE) may reserve one or more time frequency resources in an unlicensed frequency spectrum band for one or more sidelink transmissions. The UE may reserve the time frequency resources through a sidelink message transmitted in a first slot of a shared channel occupancy (CO). The UE may monitor a subset of slots before the reserved time frequency resources for sidelink transmissions from other UEs sharing the CO. The monitoring of the subset of slots may include decoding control messages or control information in each of the subset of slots, a reference signal received power (RSRP) measurement of sidelink transmissions in the subset of slots, channel sensing with energy detection in a sensing window, or a combination thereof. The UE may communicate in the reserved slot based on the monitoring.