UE Channel State Signaling for NR-U RB Set Availability
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Solution Overview
Problem
In new radio-based access to unlicensed spectrum (NRU), there is a need to determine the channel state of a first bandwidth of a cell and the availability of resource block sets (RB sets) in the active bandwidth part (BWP) due to uncertainties in multi-RB set-based listen before talk (LBT) outcomes, which affects communication reliability and efficiency.
Innovation Solution
A method and apparatus for user equipment (UE) and base station (BS) to determine the channel state of a first bandwidth of a cell by receiving or transmitting information, allowing the determination of RB set availability in the active BWP based on channel state, using downlink control information (DCI) and guard band parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multi-RB set-based LBT is performed in NRU wideband operation, then channel access can be attempted across multiple resource block sets, but the outcome of LBT cannot be ensured and predicted, leading to uncertainty in RB set availability
Solution Approach 1:
The base station performs LBT procedure in advance before transmitting data to the UE. The LBT outcome is determined beforehand, and this preliminary channel access result is then communicated to the UE through DCI format 2_0, allowing the UE to know in advance which RB sets are available for reception without performing its own LBT.
Solution Approach 2:
DCI format 2_0 serves as an intermediary message that carries the LBT outcome information from the base station to the UE. This intermediary communication mechanism allows the UE to reliably determine RB set availability based on the base station's LBT result, resolving the uncertainty that would otherwise exist in multi-RB set operations.
2Adaptability or versatility
If the UE is configured with an active BWP including multiple RB sets, then wideband operation capability is enabled, but the UE cannot predict which RB sets will be available for reception due to LBT uncertainty
Solution Approach 1:
The base station provides feedback information to the UE about the LBT outcome through DCI format 2_0. This feedback mechanism communicates which RB sets are available for reception, allowing the UE to adapt its reception operations accordingly. The feedback resolves the information loss by providing explicit availability status for each RB set in the active BWP.
Solution Approach 2:
The base station determines LBT outcomes in advance before data transmission and communicates these results to the UE through DCI format 2_0. This preliminary determination and communication of RB set availability allows the UE to be fully configured with an active BWP including multiple RB sets without uncertainty about which sets will be available for reception.
3Reliability
If LBT procedure is performed before each transmission in unlicensed spectrum, then regulatory compliance is achieved, but communication efficiency is reduced due to the need to wait for LBT completion and cannot predict transmission availability
Solution Approach 1:
The base station performs the LBT procedure in advance before data transmission and communicates the outcome to the UE through DCI format 2_0. This preliminary LBT execution and result communication allows the UE to efficiently receive data without performing its own time-consuming LBT procedure, thereby maintaining regulatory compliance while improving overall communication efficiency.
Solution Approach 2:
The base station performs the LBT procedure on its own behalf before transmission, serving the UE's need for channel access information without requiring the UE to independently perform LBT. This self-service approach by the base station eliminates the efficiency loss that would occur if each device had to perform its own LBT, while still ensuring regulatory compliance through proper channel access procedures.
Data Source
AI summary
An apparatus and a method of communication of the same are provided. A method of communication of a user equipment (UE) includes receiving, by a UE, information. The information is used to determine a channel state of a first bandwidth of a cell. This allows the UE to determine the channel state of the first bandwidth of the cell and further determine resource block set (RB set) availability of an active bandwidth part (BWP) based on the channel state of the first bandwidth.