Directional Beam Switching After LBT for Hidden-Node Interference
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Solution Overview
Problem
In wireless communication systems operating on unlicensed spectrum, directional beamforming is not considered in existing Listen-Before-Talk (LBT) procedures, leading to potential interference from hidden nodes due to directional transmission, which can result in unsuccessful receptions.
Innovation Solution
Implement receiver-assisted interference mitigation by having the transmitting node perform directional LBT for each beam and transmit request information using multiple beams, allowing the receiving node to provide feedback for selecting interference-free transmission paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If directional beamforming is used for transmission, then transmission efficiency and signal quality are improved, but interference to hidden nodes increases and reliability deteriorates
Solution Approach 1:
The transmitting node performs LBT procedure before transmission to detect channel occupancy in specific beam directions. This preliminary detection action identifies hidden nodes that would be affected by the intended transmission, allowing the system to select alternative beams or defer transmission to avoid causing interference, thus resolving the contradiction between directional transmission benefits and hidden node protection
Solution Approach 2:
The receiving node monitors incoming transmissions and provides feedback information to the transmitting node about detected interference conditions. This feedback mechanism enables the transmitting node to adjust its beam selection and transmission parameters in real-time, ensuring reliable transmission while minimizing interference to hidden nodes through continuous adaptation based on channel conditions
2Object-affected harmful factors
If omni-directional LBT is used, then hidden node interference is reduced, but transmission efficiency and signal quality deteriorate
Solution Approach 1:
The LBT procedure is segmented into multiple directional measurements corresponding to different beam directions. Instead of a single omni-directional sensing, the system divides the channel assessment into discrete angular sectors, performing LBT in each relevant direction. This segmentation enables efficient use of directional beams while systematically checking for hidden nodes in each sector, thus maintaining both transmission efficiency and hidden node protection
Solution Approach 2:
The LBT procedure applies different sensing characteristics to different spatial directions. Rather than uniform omni-directional sensing, the system tailors the LBT parameters and sensitivity to each specific beam direction's local environment. This local quality approach allows efficient transmission in directions with clear channels while being more cautious in directions where hidden nodes are detected, optimizing the balance between productivity and interference mitigation
3Reliability
If multiple beams are tested for LBT, then interference mitigation improves, but time consumption and complexity increase
Solution Approach 1:
The system performs LBT procedure on a subset of beams rather than exhaustively testing all possible beam directions. By selecting only the most relevant beams based on previous communication history, channel conditions, or spatial relationships with known nodes, the system achieves sufficient interference mitigation without the time penalty of complete beam enumeration, thus balancing reliability improvement with acceptable time consumption
Solution Approach 2:
Beam candidates for LBT testing are pre-selected based on historical channel information, spatial relationships, and communication patterns before the actual LBT procedure. This preliminary filtering reduces the number of beams that require full LBT testing, significantly cutting down the time consumption while maintaining effective interference mitigation through targeted directional sensing on the most critical beam directions
Data Source
AI summary
Apparatuses, methods, and systems are disclosed for receiver-assisted interference mitigation. One apparatus includes a processor and a transceiver that is operable on unlicensed spectrum, where the transceiver includes a plurality of UE panels. The processor generates a first TB for a first UL channel resource. Here, the first TB contains control signaling or data. The processor performs a directional LBT procedure for a first panel associated with the first UL channel resource and transmits request information to a RAN node using the first UL channel resource in response to successful directional LBT. The processor receives feedback information from the RAN node in response to the request information and transmits the first TB using the first UL channel resource in response to receiving the feedback information.