Uplink Control Indicator Transmission in Unlicensed Bands
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Solution Overview
Problem
Current LTE systems face inefficiencies in uplink transmission, particularly in handling HARQ-ACK feedback on PUSCH in unlicensed bands, due to complexities in calculating the number of coded bits and modulation order, especially when dealing with SC-FDMA symbols and resource elements.
Innovation Solution
A terminal and base station apparatus are designed to calculate the number of coded bits for HARQ-ACK based on the number of SC-FDMA symbols in an uplink slot, considering the modulation order and the value of NLBT, which is set to 1 when a time continuous signal of a first SC-FDMA symbol is generated based on a resource element corresponding to a second SC-FDMA symbol, optimizing the initial transmission of transport blocks on PUSCH.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of coded bits for HARQ-ACK is calculated based on the number of SC-FDMA symbols and modulation order in carrier aggregation with unlicensed bands, then the transmission efficiency is improved, but the calculation complexity increases due to the need to determine NLBT and handle time continuous signal generation
Solution Approach 1:
The patent changes the parameter NLBT (number of LBT symbols) from a variable that requires complex determination to a fixed value of 1 under specific conditions. When the time continuous signal of the first SC-FDMA symbol is generated based on the content of a resource element corresponding to a second SC-FDMA symbol, NLBT is set to 1, simplifying the calculation of the number of coded bits for HARQ-ACK while maintaining transmission efficiency.
Solution Approach 2:
The system uses the existing resource element content from the second SC-FDMA symbol to generate the time continuous signal for the first SC-FDMA symbol. This self-service approach eliminates the need for separate signal generation processes and reduces the complexity of determining NLBT, as the system automatically handles the signal continuity requirement.
2Productivity
If NLBT is set to 1 when time continuous signal is generated from resource element content, then the uplink transmission efficiency is improved, but the precision of HARQ-ACK feedback calculation may be affected
Solution Approach 1:
The patent establishes a conditional parameter setting where NLBT = 1 when the time continuous signal generation condition is met. This parameter change optimizes the balance between transmission efficiency and calculation precision by ensuring that the simplification only applies when the signal continuity is maintained through resource element content generation, thus preserving the integrity of HARQ-ACK feedback calculation.
Data Source
AI summary
An apparatus includes: a transmitter configured to transmit a transport block and HARQ-ACK on PUSCH; and a physical layer processing unit configured to calculate a number of coded bits for the HARQ-ACK, at least based on a number of SC-FDMA symbols NPUSCH-initialsymb for PUSCH initial transmission for the transport block, and modulation order for the transport block, wherein the number of the SC-FDMA symbols NPUSCH-initialsymb is given at least based on NLBT and a number of SC-FDMA symbols NULsymb included in an uplink slot, and a value of NLBT is 1 in a case that a time continuous signal of a first SC-FDMA symbol included in the PUSCH is generated based on a content of a resource element corresponding to a second SC-FDMA symbol following the first SC-FDMA symbol.