UE-Initiated COT for Low-Latency Unlicensed Uplink
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Solution Overview
Problem
Existing wireless communication systems face inefficiencies in uplink transmissions due to gNB-initiated Channel Occupancy Time (COT) in URLLC operations, leading to latency and reduced flexibility, especially for configured grant UL transmissions, and lack support for segmentation of repetitions in unlicensed spectrum.
Innovation Solution
Implementing a channel access method that allows user equipment (UE) to initiate COT based on configured FFP parameters, enabling flexible UL transmissions without relying on gNB detection, and harmonizing features between NR-U and URLLC for improved reliability and reduced latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gNB-initiated COT is used for UL transmissions, then UL transmissions can be performed within the COT, but latency is introduced due to dependency on gNB LBT results and DL transmission detection
Solution Approach 1:
The patent inverts the traditional gNB-initiated COT approach by enabling UE-initiated COT. Instead of the gNB acquiring the channel and allowing UE transmissions, the UE autonomously performs LBT and initiates its own COT when conditions are met, thereby eliminating the latency caused by waiting for gNB DL transmissions while maintaining transmission reliability through configured grant resources and validity symbol checking.
2Reliability
If gNB-initiated COT is used, then UL transmissions are possible, but flexibility of UL scheduling is restricted at the initial part of the FFP
Solution Approach 1:
The patent enables UE to initiate COT autonomously based on configured FFP parameters and validity symbols, inverting the traditional gNB-controlled approach. This allows UL transmissions at the initial part of FFP without waiting for gNB DL transmissions, significantly improving scheduling flexibility while maintaining reliability through configured grant resources and validation mechanisms.
Solution Approach 2:
The patent employs preliminary action by pre-configuring FFP parameters, validity symbols, and grant resources before UL transmissions. The UE uses these pre-configured parameters to autonomously determine when to initiate COT and perform UL transmissions, enabling flexible scheduling at the initial part of FFP without real-time gNB control while ensuring reliable transmissions through pre-validating resource availability.
3Reliability
If gNB-initiated COT is used, then UL transmissions can occur, but power consumption increases due to continuous gNB DL transmission requirements
Solution Approach 1:
The patent implements self-service by enabling UE to autonomously initiate COT through autonomous LBT and transmission initiation based on configured parameters. The UE independently manages its uplink transmissions without requiring continuous gNB DL transmissions to maintain COT, thereby significantly reducing gNB power consumption while ensuring reliable UL transmissions through self-managed channel access and validity symbol verification.
4Productivity
If NR-U configured-grant enhancements are applied, then UL transmission efficiency improves, but compatibility with unlicensed spectrum requirements becomes challenging
Solution Approach 1:
The patent applies local quality by introducing location-specific validity symbols within the FFP structure. Different symbols are marked as valid or invalid for UL transmissions based on local channel conditions and regulatory requirements. This allows NR-U configured-grant enhancements to operate efficiently in unlicensed spectrum by locally adapting transmission opportunities to match spectrum-specific constraints while maintaining overall system productivity.
Solution Approach 2:
The patent introduces dynamics by making the UE's COT initiation and transmission opportunities adaptive based on configured FFP parameters, validity symbols, and channel conditions. The system dynamically adjusts UL transmission timing and resources according to unlicensed spectrum requirements while maintaining high efficiency through configured grant mechanisms, thereby achieving both productivity and adaptability.
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.