Uplink Channel Access Procedures for Unlicensed Spectrum
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Solution Overview
Problem
Current wireless communication technologies face challenges in efficiently managing channel access in unlicensed radio frequency spectrum bands, particularly in reducing latency and ensuring quality of service for high-priority communications while minimizing collisions and conserving network resources.
Innovation Solution
The implementation of listen-before-talk (LBT) procedures with varying channel sensing durations and channel access priority classes, as indicated by configuration settings, to optimize channel access decisions for uplink communications in unlicensed bands, allowing for dynamic prioritization and resource allocation based on communication priority and interference levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If listen-before-talk (LBT) procedures are implemented in unlicensed bands, then channel access efficiency is improved, but latency increases due to channel sensing requirements
Solution Approach 1:
The patent implements dynamic LBT category selection where the UE can be configured with multiple LBT categories (e.g., Category 1, 2, 3, 4) with varying sensing durations and backoff parameters. The network can dynamically indicate which LBT category to use for different uplink transmissions based on current channel conditions, traffic priority, and interference levels, allowing the system to adapt between aggressive access (lower latency) and cautious access (higher efficiency) as needed
Solution Approach 2:
The patent introduces configurable parameters including number of bits for LBT category indication, channel access priority classes, and sensing duration settings. These parameters can be adjusted through RRC configuration and dynamic indication to optimize the balance between channel access efficiency and latency for different service requirements
2Reliability
If channel access priority classes are implemented, then quality of service for high-priority communications is ensured, but device complexity increases
Solution Approach 1:
The patent segments channel access into distinct priority classes (e.g., CAPC 0-3) with different QoS requirements. Each priority class has associated LBT parameters that can be independently configured, allowing high-priority traffic (e.g., URLLC) to be separated and handled with more aggressive access parameters while lower-priority traffic uses more conservative settings
Solution Approach 2:
The patent implements selective application of LBT procedures where full LBT with all its complexity is only applied when necessary. For high-priority communications, the system may use simplified LBT categories or pre-configured parameters to reduce processing overhead while still ensuring QoS, applying the full complexity of multi-category LBT only when multiple priority levels are present
3Reliability
If multiple LBT categories with varying sensing durations are used, then collision likelihood is reduced, but network resource overhead increases
Solution Approach 1:
The patent designs a unified LBT indication mechanism that can convey multiple pieces of information efficiently. The same DCI fields and RRC configuration structures are used to indicate both the LBT category and channel access priority class, allowing the network to convey multiple parameters without proportionally increasing overhead. This multi-functional indication approach reduces the resource cost of implementing collision avoidance
Solution Approach 2:
The patent applies different levels of LBT complexity and indication overhead locally based on traffic requirements. For homogeneous traffic with uniform priority, simplified LBT category indication is used. For heterogeneous traffic with multiple priority levels, the full multi-category LBT mechanism is activated, allowing the system to optimize resource usage by applying detailed LBT management only where collision avoidance is most critical
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive a configuration that indicates a number of bits to be used in an indication of at least one of a listen-before-talk (LBT) category or a channel access priority class to be used for uplink communications. The UE may receive the indication of at least one of the LBT category or the channel access priority class to be used for a transmission starting point associated with one or more uplink communications, wherein the indication includes the number of bits indicated in the configuration. The UE may perform an LBT procedure for an uplink communication, of the one or more uplink communications, transmitted at the transmission starting point, according to the LBT category or the channel access priority class. Numerous other aspects are provided.