U-LTE Terminal Feedback Transmission via Dynamic Uplink Subframe Association
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Solution Overview
Problem
In the LTE system, ensuring proper ACK/NACK feedback information transmission in the unlicensed spectrum is challenging due to the opportunity-based data transmission and flexible uplink/downlink configuration, which makes it difficult to maintain a predefined timing relationship between PDSCH and HARQ-ACK, especially in U-LTE scenarios.
Innovation Solution
A method where a terminal device determines associated uplink subframes based on received downlink subframes and sends feedback information in multiple uplink subframes, using feedback information codebooks and channels to optimize resource utilization and ensure successful transmission, even in scenarios where traditional timing relationships are disrupted.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a predefined timing relationship between PDSCH and HARQ-ACK is maintained in LTE system, then feedback information transmission is ensured in licensed spectrum, but it becomes difficult to adapt to flexible uplink/downlink configuration in unlicensed spectrum
Solution Approach 1:
The patent implements dynamic determination of uplink subframes based on actual downlink subframe reception. Instead of using fixed predefined timing relationships, the terminal device dynamically identifies which uplink subframes are available and determines the timing offset K1 adaptively. This allows the system to flexibly adjust to varying uplink/downlink configurations in unlicensed spectrum while maintaining reliable feedback transmission by ensuring feedback is sent in valid uplink subframes.
Solution Approach 2:
The patent changes the timing parameter K1 from a fixed predefined value to a dynamically determined value based on actual channel conditions and configuration. The terminal device receives downlink data in subframe n and determines to send feedback in uplink subframe n+K1, where K1 is adaptively selected based on available uplink subframes and timing requirements. This parameter change enables adaptation to flexible configurations while maintaining transmission reliability.
2Adaptability or versatility
If opportunity-based data transmission is used in unlicensed spectrum, then resource sharing and coexistence is improved, but predefined timing relationships between PDSCH and HARQ-ACK cannot be maintained
Solution Approach 1:
The patent applies preliminary action by having the terminal device monitor and identify available uplink subframes in advance before feedback is needed. The device determines the set of uplink subframes that can be used for feedback transmission and prepares the timing offset K1 selection based on this pre-identified information. This preliminary identification of valid uplink subframes ensures that when feedback needs to be sent, the terminal can immediately determine the appropriate timing without violating timing relationships, even in opportunity-based transmission scenarios.
3Reliability
If feedback information is sent in multiple uplink subframes, then transmission success probability is improved, but resource utilization may be optimized further
Solution Approach 1:
The patent segments the feedback transmission process by identifying multiple candidate uplink subframes (n+K1, n+K2, etc.) and determining a set of downlink subframes that can be associated with each uplink subframe. This segmentation allows the terminal to distribute feedback information across multiple uplink opportunities, improving transmission success probability. The resource utilization is optimized by systematically managing which downlink subframes are associated with which uplink subframes, avoiding redundant transmissions and efficiently using available uplink resources.
Data Source
AI summary
The method disclosed in present embodiments includes: a terminal device receives downlink data in at least one downlink burst; determines that a first downlink subframe set is associated with a first uplink subframe, where the first downlink subframe set belongs to the at least one downlink burst, the first uplink subframe is used to send first feedback information corresponding to the first downlink subframe set, the first uplink subframe is in a first uplink burst, and the first uplink burst follows the at least one downlink burst; determines a first feedback information codebook, and determines the first feedback information based on the codebook; determines a first uplink channel in the first uplink subframe; and sends the first feedback information to the access network device on the first uplink channel. According to the method, the terminal device can properly sends ACK/NACK feedback information in a U-LTE scenario.