Uplink Cancellation for Full-Duplex LBT in Unlicensed Spectrum
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Solution Overview
Problem
Current wireless communication systems, particularly in 5G NR, face challenges in efficiently managing uplink (UL) transmissions during listen-before-talk (LBT) procedures in unlicensed spectra, leading to potential interference and reduced channel availability for downlink (DL) communications in full-duplex (FD) modes.
Innovation Solution
Implementing UL cancelation-assisted LBT procedures, where base stations and user equipment (UEs) can cancel or postpone UL transmissions based on indications received from each other, allowing for more effective channel assessment and prioritization of DL transmissions by determining the priority of UL resources and adjusting UL transmissions accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UL transmissions are performed during LBT procedure in unlicensed spectrum, then UL communication continuity is maintained, but channel availability for DL communications is reduced and interference increases
Solution Approach 1:
The base station performs LBT procedure in advance to determine channel availability before scheduling UL transmissions. By conducting the LBT check beforehand and providing cancellation indication to the UE, the system ensures that UL transmissions are only performed when the channel is available, thus preventing interference with DL communications while maintaining UL communication continuity when conditions permit.
Solution Approach 2:
The base station provides feedback to the UE in the form of cancellation indication based on the LBT result. This feedback mechanism allows the UE to adjust its transmission behavior accordingly - either proceeding with UL transmission when the channel is available or canceling when it is not, thereby resolving the contradiction between maintaining UL continuity and ensuring DL channel availability.
2Productivity
If UL transmissions are canceled based on LBT procedure, then channel availability for DL communications is improved, but UL transmission reliability is reduced
Solution Approach 1:
The LBT procedure is performed in advance to predict channel availability before UL transmission. By determining the channel state beforehand and providing cancellation indication to the UE, the system avoids performing UL transmissions that would cause interference, thus improving DL channel availability while maintaining UL reliability only when conditions are favorable.
Solution Approach 2:
The cancellation indication serves as feedback from the base station to the UE, conveying the result of the LBT procedure. This feedback enables the UE to make informed decisions about transmission cancellation, balancing the need for DL channel availability with UL transmission reliability based on actual channel conditions.
3Productivity
If multiple UL transmissions are managed with different priorities, then efficient resource allocation is achieved, but device complexity increases
Solution Approach 1:
The system segments UL transmissions into different priority levels (e.g., high priority and low priority). By dividing transmissions into distinct priority categories, the base station can apply different cancellation policies to different segments, achieving efficient resource allocation where high priority transmissions are protected from cancellation while low priority transmissions can be canceled when needed, without requiring complex individual management of each transmission.
Solution Approach 2:
Different quality levels (priorities) are assigned to different UL transmissions based on their importance. This local differentiation allows the system to apply appropriate cancellation decisions to each transmission segment based on its specific quality requirement, achieving efficient resource allocation while keeping the management mechanism relatively simple through standardized priority levels.
Data Source
AI summary
The apparatus may be a UE configured to communicate, in a FD mode, with at least one base station via an unlicensed spectrum; determine to cancel at least one UL transmission corresponding to one or more UL resources, the one or more UL resources corresponding to a LBT procedure; and cancel, based on the determination, the at least one UL transmission corresponding to the one or more UL resources. The apparatus may be a base station configured to communicate, in a FD mode, with one or more UEs via an unlicensed spectrum; determine that a LBT procedure associated with DL scheduling will occur via a set of UL resources; and transmit, to the one or more UEs based on the determination, an indication of a cancelation of one or more UL transmissions during the set of UL resources.