HARQ Retransmission Coding With Adaptive Polar and LDPC Rates
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Solution Overview
Problem
Current communication systems face challenges in efficiently utilizing polar codes and LDPC codes, particularly in cellular networks, due to limitations in code construction, channel resource management, and the need for flexible coding rates to support varying channel conditions and retransmissions.
Innovation Solution
The implementation of polar codes for successive HARQ retransmissions and the use of rate-compatible LDPC codes based on protographs, which allow for adaptive coding rates and efficient resource allocation through methods like incremental freezing and diversified polar codes, as well as LDPC code construction using protograph matrices for supporting different input block lengths and coding rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polar codes are used for HARQ retransmissions with fixed block lengths, then code construction is simplified, but adaptability to varying channel conditions and retransmission scenarios is reduced
Solution Approach 1:
The patent implements dynamic code construction by allowing the polar code block length to vary based on the number of information bits to be transmitted. Instead of fixing the block length to a power of 2, the system dynamically selects the block length N to match the actual data size, enabling adaptive response to varying channel conditions and retransmission scenarios while maintaining the structured benefits of polar codes
Solution Approach 2:
The patent changes the parameter of code block length from fixed (power of 2) to variable (matching information bit count). This parameter change allows the system to adapt to different channel conditions, retransmission requirements, and data sizes without being constrained by fixed block length limitations, thereby resolving the contradiction between construction simplicity and adaptability
2Ease of operation
If the coded block length is set to a power of 2, then polar code encoding and decoding is simplified, but flexibility in supporting arbitrary information bit lengths and coding rates is lost
Solution Approach 1:
The system dynamically determines the coded block length N based on the actual number of information bits K and desired coding rate R, rather than forcing N to be a power of 2. This dynamic approach maintains encoding/decoding simplicity through structured polar code construction while achieving flexibility in supporting arbitrary bit lengths and coding rates required by practical communication scenarios
Solution Approach 2:
The patent changes the parameter constraint on coded block length from 'must be power of 2' to 'can be any integer matching data size'. This parameter relaxation enables the system to support arbitrary information bit lengths and coding rates while maintaining the mathematical structure of polar codes for efficient encoding and decoding operations
3Stability of the object's composition
If puncturing is applied to match power of 2 block lengths, then polar code structure is maintained, but transmission efficiency is reduced due to removed bits
Solution Approach 1:
The patent eliminates the need for puncturing by dynamically setting the coded block length N to match the actual information bit count K. This dynamic code construction maintains polar code structural integrity through proper frozen bit placement while avoiding the transmission efficiency loss associated with puncturing, as no bits are unnecessarily removed from the code block
Solution Approach 2:
The patent changes the code block length parameter from fixed power-of-2 values requiring puncturing to variable lengths matching actual data size. This parameter change maintains code structure integrity through proper polar code construction while eliminating the need for puncturing, thereby preserving transmission efficiency by transmitting only the necessary bits
4Adaptability or versatility
If rate-compatible LDPC codes based on protographs are used, then adaptability to different coding rates is improved, but code construction complexity increases
Solution Approach 1:
The patent segments the LDPC code construction into a reusable protograph template and variable expansion parameters. The base protograph contains the essential code structure, while different coding rates are achieved by scaling the code block length through the lifting parameter. This segmentation reduces construction complexity by reusing the same protograph structure across different rates while maintaining adaptability through parameter variation
Solution Approach 2:
The patent creates a universal protograph-based LDPC code construction that can generate codes at multiple coding rates using the same base structure. The protograph serves as a multi-functional template that, when expanded with different lifting parameters, produces rate-compatible codes adapted to various channel conditions and retransmission scenarios, thereby reducing overall system complexity through code reuse
Data Source
AI summary
A method may comprise receiving a first signal comprising first LDPC bits including systematic bits and parity bits and transmitting information indicating that the first signal was incorrectly received. A second signal comprising second LDPC bits may be received in response to the transmitting. The second signal may include LDPC bits according to a lifting size of an LDPC base graph.