Terminal LBT Mechanism for Unlicensed Band D2D Feedback
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Solution Overview
Problem
In wireless communication systems, device-to-device (D2D) direct communication in unlicensed bands faces challenges in adhering to regulatory requirements, particularly in higher frequency bands like 52.6 GHz to 71 GHz, where Listen Before Talk (LBT) protocols are necessary to avoid interference.
Innovation Solution
A terminal is designed with a reception unit for receiving control and shared channels, a control unit to perform LBT before transmitting feedback, and a transmission unit to send feedback only if no power exceeding a threshold is detected during LBT, ensuring compliance with unlicensed band regulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If D2D communication is performed in unlicensed band, then communication capability is improved, but interference with other systems occurs
Solution Approach 1:
The terminal performs LBT (Listen Before Talk) operation before transmitting feedback signals to detect whether the channel is occupied by other systems. By conducting this preliminary detection action, the terminal can identify potential interference conditions and adjust its transmission accordingly, thereby preventing harmful interference while maintaining communication capability in unlicensed bands
2Productivity
If feedback signals are transmitted without LBT, then communication efficiency is improved, but regulatory compliance deteriorates
Solution Approach 1:
The terminal performs LBT operation as a preliminary action before transmitting feedback signals. This ensures compliance with unlicensed band regulations that require channel sensing before transmission. The LBT process checks for occupying signals from other systems, and only allows feedback transmission when the channel is clear, thus maintaining both regulatory compliance and efficient communication
3Measurement precision
If LBT period is extended, then interference detection accuracy is improved, but transmission delay increases
Solution Approach 1:
The terminal performs LBT operation for a specific period (e.g., 16 microseconds) before feedback transmission, which is sufficient to detect occupying signals from other systems without causing excessive delay. This partial action approach balances the need for adequate detection accuracy with the requirement to minimize transmission delay, avoiding both insufficient sensing and overly long waiting periods
Data Source
AI summary
A terminal includes: a reception unit configured to receive a control channel and a shared channel in an unlicensed band from another terminal; a control unit configured to perform an LBT (Listen before talk) for a period in a symbol immediately before a resource of a feedback channel corresponding to the shared channel or in a first symbol of the resource of the feedback channel; and a transmission unit configured to transmit a feedback to the another terminal in the resource of the feedback channel in a case where a power exceeding a threshold value is not detected in the LBT.