Uplink Control Information Transmission via LBT Detection
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Solution Overview
Problem
In LTE systems using Licensed Assisted Access (LAA), uplink control information transmission over unlicensed carriers is hindered by the Listen Before Talk (LBT) mechanism, leading to potential failures in Acknowledgement (ACK)/Negative Acknowledgment (NACK) feedback, resulting in delayed or incorrect transmission of uplink control information due to channel preempting issues.
Innovation Solution
A method and device for determining uplink control information based on feedback window size and position, performing LBT detection at specific transmission times, and repeating the detection until successful, to determine the actual uplink transmission time, ensuring timely and correct transmission of uplink control information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal applies LBT mechanism before transmitting uplink control information over unlicensed carriers, then the channel access is controlled to avoid collision, but the terminal may be unable to access the channel at certain time when another system occupies the unlicensed band
Solution Approach 1:
The patent applies preliminary action by having the terminal perform LBT detection in advance before the scheduled uplink transmission time. The terminal determines whether to transmit uplink control information based on the result of this preliminary LBT detection, and if the channel is found to be occupied, the terminal waits for the next available transmission opportunity. This advance preparation resolves the contradiction by ensuring channel availability before transmission while managing the time loss through proactive channel assessment.
2Reliability
If the terminal repeats LBT detection until successful, then the uplink control information transmission reliability is improved, but the transmission time is extended
Solution Approach 1:
The patent implements feedback by having the terminal continuously monitor the result of LBT detection and adjust its transmission timing accordingly. After each LBT detection attempt, the terminal receives feedback about whether the channel is available, and based on this feedback, determines whether to proceed with transmission or wait for the next opportunity. This feedback mechanism ensures reliable transmission while managing detection duration through iterative assessment.
3Reliability
If the uplink control channel is transmitted over the licensed primary carrier, then the transmission is stable, but the overhead of uplink control channels over the licensed carrier becomes considerable
Solution Approach 1:
The patent applies dimensionality change by transitioning the uplink control information transmission from the licensed primary carrier (time domain) to the unlicensed secondary carrier (frequency domain). This spatial redistribution allows the system to reduce overhead on the licensed carrier while utilizing the unlicensed band for control information, effectively managing the quantity of control channels through dimensional migration.
Data Source
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AI summary
A method and device for transmitting uplink control information, which are used for solving the problem existing in the art that if listen-before-talk detection on a corresponding unlicensed carrier fails, feedback information cannot be transmitted. In the embodiments of the present invention, the method comprises: according to the size and position of a feedback window, determining uplink control information; according to a transmission moment of the uplink control information, performing listen-before-talk detection to determine an actual uplink transmission moment; and transmitting the determined uplink control information at an actual uplink transmission moment. In the embodiments of the present invention, under the situation where no channel is occupied at a set uplink control information transmission moment, one or more times of listen-before-talk detection are continued, and the determined uplink control information is transmitted on an actual uplink transmission moment, thereby avoiding the situation that uplink control information cannot be correctly transmitted in time due to not occupying a channel, and further improving the system performance.