UE-Initiated Channel Access for Low-Latency NR-U Uplink
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Solution Overview
Problem
Existing wireless communication systems, particularly in NR-U and URLLC, face inefficiencies with gNB-initiated COT, leading to increased latency and reduced flexibility in uplink transmissions due to dependency on gNB DL transmissions, and lack of support for segmentation and repetition in unlicensed spectrum.
Innovation Solution
Implementing a UE-initiated COT mechanism that allows UEs to independently initiate channel occupancy time based on configured FFP parameters, enabling flexible uplink transmissions and reducing latency by allowing UL transmissions at the beginning of each frame period without relying on gNB DL signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gNB-initiated COT is used, then downlink transmissions can be performed, but uplink transmission latency increases and flexibility is reduced
Solution Approach 1:
The patent inverts the traditional gNB-initiated COT mechanism by enabling UE-initiated COT. Instead of the gNB acquiring the channel and granting uplink resources, the UE autonomously performs LBT and initiates COT when conditions are met, thereby reducing uplink latency while maintaining reliability through configured grant resources and validity symbol checks.
Solution Approach 2:
The patent applies preliminary action by pre-configuring uplink resources and validity symbols through RRC signaling before the actual transmission. The UE is provided with configured grant resources, validity symbol configurations, and COT initiation conditions in advance, allowing it to quickly initiate transmission when channel conditions permit, without waiting for gNB scheduling decisions.
2Reliability
If gNB-initiated COT is used, then downlink control can be maintained, but uplink scheduling flexibility is reduced
Solution Approach 1:
The patent introduces dynamic UE-initiated COT capability that adapts to traffic conditions. The gNB configures multiple COT initiation conditions and validity symbol patterns, allowing the UE to dynamically select appropriate transmission parameters based on channel state and traffic requirements, thereby achieving both control reliability and scheduling flexibility.
Solution Approach 2:
The patent segments the COT initiation process into configurable conditions and validation steps. The gNB provides segmented configurations including validity symbol patterns, COT initiation conditions, and resource assignments, allowing the UE to independently validate and initiate transmission only when specific conditions are met, enhancing both reliability and flexibility.
3Reliability
If gNB retains acquired COT for DL transmission, then UL transmission can be triggered, but power consumption increases and overhead increases
Solution Approach 1:
The patent implements self-service by enabling the UE to autonomously initiate COT and perform uplink transmission without requiring the gNB to retain and retransmit downlink signals. The UE independently performs LBT, validates conditions, and initiates transmission based on pre-configured parameters, significantly reducing power consumption and signaling overhead while maintaining reliable transmission triggering.
Data Source
AI summary
A user equipment (UE) executes a semi-static channel access method during a random access procedure in an unlicensed band. A base station transmits configuration information and downlink (DL) information to the UE in a fixed frame period (FFP) according to a set of FFP parameters associated with the base station. The UE determines whether to initiate a channel occupancy time (COT) in an FFP according to a set of FFP parameters associated with the UE based on one or more of: at least one condition in the configuration information, at least one condition in scheduling information, at least one condition in DL information, and a detection result of detecting transmission of the DL information. The base station determines whether to use the UE-initiated COT shared from the UE.