Full-Duplex Downlink Cancellation for Accurate Listen-Before-Talk
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Solution Overview
Problem
In wireless communications, full-duplex devices face interference from downlink transmissions during listen-before-talk (LBT) procedures, leading to inaccurate channel availability assessments and resource inefficiencies.
Innovation Solution
The base station modifies downlink transmissions by cancelling or rate matching them during clear channel assessment (CCA) resources to prevent interference, allowing the user equipment (UE) to perform a more accurate LBT and ensure reliable channel availability determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the base station transmits downlink signals during CCA resources, then the downlink transmission continuity is maintained, but the LBT procedure accuracy deteriorates due to self-interference
Solution Approach 1:
The downlink transmission is segmented into two parts: resources that overlap with CCA resources are cancelled, while non-overlapping resources continue transmission. This segmentation allows the UE to perform accurate LBT without downlink interference while maintaining partial downlink transmission efficiency.
Solution Approach 2:
Instead of completely cancelling all downlink transmissions during CCA resources, only the portion that overlaps with CCA resources is cancelled. This partial action approach maintains downlink transmission efficiency for non-overlapping resources while ensuring LBT procedure accuracy.
2Productivity
If the UE performs LBT procedure while receiving downlink transmission, then full-duplex operation is achieved, but measurement precision deteriorates due to self-interference
Solution Approach 1:
The harmful downlink transmission components are extracted and removed from the resources that overlap with CCA resources. This extraction eliminates the self-interference that would otherwise degrade the LBT measurement precision while allowing full-duplex operation in non-overlapping resources.
Solution Approach 2:
Different quality requirements are applied to different resource portions: CCA resources require high measurement precision (with downlink cancellation), while non-CCA resources can maintain normal downlink transmission. This local quality differentiation resolves the contradiction between full-duplex efficiency and measurement accuracy.
3Measurement precision
If downlink transmission is cancelled during CCA resources, then LBT accuracy is improved, but downlink transmission continuity deteriorates
Solution Approach 1:
The downlink transmission timeline is segmented into CCA resources and non-CCA resources. Cancellation is applied only to the CCA portion, while non-CCA portions maintain continuity. This segmentation improves measurement precision during CCA while preserving downlink transmission continuity elsewhere.
Solution Approach 2:
Instead of completely interrupting downlink transmission, only the partial portion overlapping with CCA resources is cancelled. This partial action maintains LBT accuracy while preserving downlink transmission continuity for the majority of non-overlapping resources.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A communication device, which may be known as user equipment (UE), may be capable of full-duplex communications. The UE may determine that at least a portion of a downlink transmission that the UE may receive while concurrently scheduled to transmit an uplink transmission, may overlap with a clear channel assessment (CCA) procedure (e.g., a listen-before-talk (LBT) operation) in a shared radio frequency spectrum band. The UE may determine that at least a portion of the downlink transmission that overlaps with the LBT resources may be canceled or the downlink transmission may be rate matched and allocated to resources outside of the LBT resources. As a result, the UE may perform an LBT procedure without interference caused by the UE receiving the downlink transmission.