Multi-Subband Uplink LBT via Adaptive Category Selection
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Solution Overview
Problem
In wireless communications systems, especially in unlicensed spectra, devices face challenges in performing listen before talk (LBT) procedures on multiple subbands within the limited time available, which can lead to inefficient resource allocation and potential collisions.
Innovation Solution
A base station supports communication with user equipment (UE) via multiple subbands by transmitting an uplink grant that allocates resources for a shared data channel. The base station indicates the type of LBT procedure, such as category 4 or category 2, for each subband, allowing the UE to perform the appropriate LBT based on the subband occupancy and base station's channel availability information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wireless device performs LBT on all subbands, then channel occupancy reliability is improved, but transmission time exceeds available preparation time
Solution Approach 1:
The patent segments the LBT procedure into two distinct types: Category 2 LBT (single subband, shorter duration) and Category 4 LBT (multiple subbands, longer duration). The base station configures the UE to perform Category 2 LBT on a first subset of subbands and Category 4 LBT on a second subset of subbands, allowing the UE to complete LBT on all subbands within the available preparation time while maintaining channel occupancy reliability.
Solution Approach 2:
The patent applies different LBT procedure types to different subsets of subbands based on local conditions. The base station determines which subbands require Category 2 LBT versus Category 4 LBT based on channel occupancy status and UE capabilities, optimizing the LBT approach for each specific subband group rather than applying a uniform procedure across all subbands.
2Object-affected harmful factors
If a wireless device performs Category 4 LBT on all subbands, then collision avoidance is improved, but transmission preparation time is exceeded
Solution Approach 1:
The patent divides the subbands into two subsets: a first subset where Category 2 LBT is performed (shorter duration, less collision avoidance) and a second subset where Category 4 LBT is performed (longer duration, better collision avoidance). This segmentation allows the system to balance collision avoidance requirements with the constraint of available transmission preparation time.
Solution Approach 2:
Instead of performing the full Category 4 LBT procedure on all subbands (excessive action), the patent applies Category 2 LBT to the first subset of subbands where shorter monitoring is sufficient, and reserves Category 4 LBT for the second subset where enhanced collision avoidance is needed. This partial application of the more thorough LBT procedure prevents time overflow while maintaining adequate collision avoidance.
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AI summary
Methods, systems, and devices for wireless communications are described that support listen before talk (LBT) for uplink transmissions using multiple subbands. A base station may support communication with a user equipment (UE) via multiple subbands and may transmit an uplink grant to the UE that allocates resources of the multiple subbands for transmission of a shared data channel by the UE. The base station may include an indication within the uplink grant that indicates to the UE to perform a given type of LBT for each subband. After transmitting the uplink grant, the base station may transmit control information or other signaling (e.g., channel occupancy time system information (COT-SI)) that indicates subbands on which the UE is to perform a given type of LBT or other subbands on which the UE is to perform a different type of LBT.