Uplink Control Information Transmission in Multi-Subframe Scheduling
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Solution Overview
Problem
In the LTE system, ensuring efficient transmission of uplink control information such as channel state information, sounding reference signals, and hybrid automatic repeat request acknowledgments in a multi-subframe scheduling scenario is challenging, especially when using unlicensed spectrum resources, as existing methods struggle to determine optimal subframe positions for transmission, leading to inefficiencies and potential losses in data transmission.
Innovation Solution
A method for transmitting uplink control information in a multi-subframe scheduling scenario, where the terminal device determines an uplink subframe other than the first subframe in a sequence to carry control information, allowing for flexible scheduling and increased opportunities for data transmission by performing clear channel assessments before subsequent subframes, ensuring reliable and efficient data transmission even if initial subframes are not available for unlicensed spectrum use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal device transmits uplink control information in the first uplink subframe, then the transmission timing is fixed and simple, but the transmission opportunity may be lost if the unlicensed spectrum is occupied
Solution Approach 1:
The patent makes the uplink control information transmission subframe dynamic by allowing the terminal to select from multiple candidate subframes based on LBT results, rather than using a fixed subframe. This dynamic selection adapts to the actual channel conditions in unlicensed spectrum, improving transmission reliability while managing complexity through predefined candidate sets.
Solution Approach 2:
The patent performs preliminary LBT (Listen Before Talk) operations in multiple candidate uplink subframes before transmission. By proactively checking channel availability in advance across multiple subframes, the system prepares transmission opportunities ahead of time, ensuring that control information can be transmitted as soon as a clear channel is detected.
2Reliability
If multiple clear channel assessments are performed in multiple subframes, then the opportunity for transmitting control information increases, but the time consumption and complexity increase
Solution Approach 1:
The patent segments the uplink subframes into multiple candidate subframes within a predefined window, allowing LBT operations to be distributed across these segments. This segmentation enables parallel or sequential assessment without requiring the entire transmission window to be consumed by a single assessment process, efficiently utilizing time resources.
Solution Approach 2:
The patent performs LBT operations in multiple candidate subframes (excessive action) to ensure transmission success, rather than limiting to a single assessment. By conducting more LBT operations than the minimum single-subframe requirement, the system increases the probability of finding an available channel, accepting the additional time cost as necessary for reliable unlicensed spectrum transmission.
3Productivity
If the first uplink subframe is used for control information transmission, then the scheduling is simple, but the downlink data transmission efficiency decreases when unlicensed spectrum is occupied
Solution Approach 1:
The patent dynamically adjusts the uplink control information transmission timing based on LBT results in multiple candidate subframes, rather than using a fixed schedule. This dynamic scheduling adapts to unlicensed spectrum availability, maximizing downlink data transmission efficiency by ensuring control information is transmitted as soon as possible, thereby enabling timely HARQ feedback and maintaining high throughput.
Solution Approach 2:
The system performs preliminary LBT assessments in multiple candidate uplink subframes before actual transmission. By proactively identifying available subframes in advance, the scheduling complexity is managed through predefined candidate sets and clear selection rules, while achieving high productivity by minimizing delays in control information transmission and subsequent downlink data operations.
Data Source
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AI summary
Embodiments of the present invention disclose a method and an apparatus for transmitting uplink control information. The method for transmitting uplink control information in the embodiments of the present invention includes: receiving, by a terminal device, scheduling information and trigger information from an access network device, where the scheduling information is used to instruct the terminal device to transmit, in M uplink subframes, uplink data scheduled by the scheduling information, M is a positive integer not less than 2, and the trigger information is used to instruct the terminal device to send uplink control information; determining, by the terminal device, in the M uplink subframes, an uplink subframe for carrying the uplink control information, where the determined uplink subframe is a subframe other than a first subframe in the M uplink subframes, and the first subframe is a first uplink subframe in the M uplink subframes; and sending, by the terminal device, the uplink control information in the determined uplink subframe.