QAM Codebook Variation for HARQ Decoding Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current hybrid automatic repeat request (HARQ) technologies, such as soft combining (CC) and incremental redundancy (IR), face limitations in decoding performance and complexity, particularly in soft combining where decoding accuracy is low and in IR where long code decoding increases complexity, especially in polar code IR-HARQ systems.
Innovation Solution
A data sending method using quadrature amplitude modulation (QAM) codebooks, where a first device sends data modulated with a first QAM codebook, and upon decoding failure, sends a subset of the data modulated with a different QAM codebook, with the second device jointly decoding the data, thereby reducing bit error rates and improving accuracy by varying the QAM codebooks used for retransmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If soft combining (CC) HARQ technology is used to retransmit data, then the transmission reliability is improved, but the decoding accuracy deteriorates because completely same encoded bits are sent each time
Solution Approach 1:
The patent applies parameter changes by varying the QAM codebook used for modulation in each retransmission. Instead of using the same codebook repeatedly (CC-HARQ), the system changes the codebook parameters (e.g., from first QAM codebook to second QAM codebook) to generate different modulated signals with increased minimum distance, thereby improving both reliability and decoding accuracy simultaneously
2Measurement precision
If incremental redundancy (IR) HARQ technology with long encoding sequence is used, then the decoding performance is improved, but the device complexity increases due to requirement of long code decoder
Solution Approach 1:
The patent avoids long code decoders by changing the modulation codebook parameters instead. The system achieves improved decoding performance through varying QAM codebooks across retransmissions, which increases the minimum distance between constellation points without requiring complex long code decoding structures
Solution Approach 2:
The patent substitutes the mechanical/structural complexity of long code decoders with a simpler approach of varying modulation codebooks. Instead of using a complex decoder architecture, the system achieves better performance through parameter variation in the modulation stage, replacing complex decoding mechanics with simpler modulation diversity
3Measurement precision
If polar code IR-HARQ is used to achieve additional long code gain, then the decoding accuracy is improved, but the construction complexity and bit mapping complexity increase excessively
Solution Approach 1:
The patent avoids the construction complexity of polar code IR-HARQ by using parameter changes in QAM codebooks instead. The system achieves improved decoding accuracy through varying the modulation codebook parameters across retransmissions, which provides diversity gain without the excessive construction and bit mapping complexity of polar code approaches
Data Source
AI summary
This application provides a data sending method and an apparatus. The method includes: A first device sends, to a second device, first data modulated by using a first quadrature amplitude modulation codebook. The second device receives, from the first device, the first data modulated by using the first quadrature amplitude modulation codebook. When the second device fails to decode the first data modulated by using the first quadrature amplitude modulation codebook, the first device sends, to the second device, second data modulated by using a second quadrature amplitude modulation codebook. The second data is a part or all of the first data, and the first quadrature amplitude modulation codebook is different from the second quadrature amplitude modulation codebook. The second device receives, from the first device, the second data modulated by using the second quadrature amplitude modulation codebook, and jointly decodes the first data and the second data.