Dynamic HARQ-ACK Codebook Size for Unlicensed Spectrum
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Solution Overview
Problem
In wireless communication systems, particularly in LTE, the transmission of HARQ-ACK feedback information on unlicensed spectrum faces challenges due to LBT requirements and channel availability issues, necessitating a flexible signaling scheme to adjust the size and content of the feedback information effectively.
Innovation Solution
A method and apparatus for transmitting uplink control information, which includes scheduling information indicating the use of reserved or shared resource elements for HARQ-ACK feedback, allowing for flexible bundling and multiplexing with user data, and adjusting the size based on the number of HARQ processes, to ensure reliable and efficient communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If HARQ-ACK feedback information is transmitted on unlicensed spectrum, then communication capacity is improved, but channel availability and transmission reliability deteriorate due to LBT requirements and interference
Solution Approach 1:
The patent implements dynamic HARQ-ACK codebook size adjustment based on actual downlink data transmissions. The codebook size is determined by the number of received downlink assignments rather than being fixed, allowing the system to adapt to varying channel conditions and LBT outcomes. This dynamic approach optimizes resource utilization while maintaining reliable feedback transmission in unlicensed spectrum environments
Solution Approach 2:
The patent changes the parameter of HARQ-ACK codebook size from a fixed value to a variable determined by the number of downlink assignments received. This parameter change enables the system to adjust feedback information size according to actual transmission needs, improving both productivity and reliability by matching resource allocation to channel conditions
2Ease of operation
If fixed size HARQ-ACK codebook is used, then transmission simplicity is improved, but resource efficiency and adaptability deteriorate
Solution Approach 1:
The patent transitions from a static codebook size to a dynamic codebook size that adapts to the number of downlink assignments. This dynamic mechanism maintains operational simplicity through standardized procedures while dramatically improving resource efficiency by allocating feedback resources proportional to actual data transmissions
Solution Approach 2:
The codebook size parameter is changed from fixed to variable, directly linking it to the number of downlink assignments. This parameter change enables the system to maintain simplicity in implementation while achieving superior resource efficiency through adaptive sizing
3Loss of information
If HARQ-ACK feedback size is increased to cover all possible processes, then feedback completeness is improved, but transmission overhead and resource consumption increase
Solution Approach 1:
The patent extracts only the necessary HARQ-ACK feedback bits corresponding to actual downlink assignments from the full set of possible HARQ processes. By including only relevant feedback information in the codebook, the system achieves complete feedback for transmitted data while minimizing transmission overhead by excluding feedback for inactive processes
Solution Approach 2:
Instead of transmitting feedback for all possible HARQ processes (excessive action), the patent transmits feedback only for the subset of processes that have actual downlink assignments (partial action). This approach ensures feedback completeness for relevant data while reducing overall transmission overhead
Data Source
AI summary
A method including receiving one or more data packets wirelessly in one or more downlink transmission opportunities on one or more radio carriers, receiving scheduling information including an indication of uplink control information to be transmitted related to at least one of the one or more data packets, and causing wireless transmission of the uplink control information in an uplink transmission opportunity.