HARQ Retransmission With LDPC Redundancy Version Bit Selection
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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 restrictions on coded block lengths and the need for puncturing schemes that affect coding rates and channel resource allocation.
Innovation Solution
The proposed solution involves using polar codes for successive HARQ retransmissions with varying information bit lengths and LDPC codes with rate-compatible protograph matrices to adapt coding rates, along with puncturing and CRC schemes, to optimize data transmission in cellular systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If polar codes are used with fixed block lengths that are powers of 2, then encoding and decoding complexity is reduced, but flexibility in adapting to different information bit lengths and coding rates is lost
Solution Approach 1:
The patent applies dynamics by making the frozen bit set configurable rather than fixed. The network can dynamically adjust which bits are frozen based on the required coding rate and block length, allowing the system to adapt to different transmission conditions while maintaining the power-of-2 block length structure that simplifies encoding and decoding
Solution Approach 2:
The patent changes the parameter of frozen bit positions from a fixed configuration to a configurable one. By allowing the frozen bit set to be adjusted according to different coding rates and block lengths, the system achieves versatility without sacrificing the computational simplicity of polar codes with power-of-2 block lengths
2Adaptability or versatility
If puncturing is applied to polar code outputs to match non-power-of-2 block lengths, then flexibility in block length is improved, but coding rate and error correction performance deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-configuring the frozen bit set according to the required coding rate and block length before encoding. This allows the system to achieve the desired block length without puncturing, as the frozen bits are strategically placed to provide both the required block length and sufficient error correction capability from the start
Solution Approach 2:
The patent changes the approach from post-encoding puncturing to pre-encoding configuration of frozen bits. By adjusting the frozen bit set parameters based on the required coding rate and block length, the system achieves block length flexibility while maintaining error correction performance, as the polar code structure is optimized before encoding rather than degrading it through puncturing
3Reliability
If different polar codes are used for each HARQ retransmission to adapt to channel conditions, then error correction performance is improved, but device complexity and processing overhead increase
Solution Approach 1:
The patent applies universality by using a single polar code structure with a configurable frozen bit set that serves multiple functions. The same encoder and decoder can handle different coding rates, block lengths, and retransmission scenarios by simply reconfiguring which bits are frozen, eliminating the need for multiple specialized codes while maintaining adaptability to different channel conditions
Solution Approach 2:
The patent changes the approach from using multiple different polar codes to using one polar code structure with variable frozen bit set parameters. This parameter-based configuration allows the system to adapt to different channel conditions and retransmission requirements without increasing device complexity, as the underlying encoding and decoding algorithms remain the same
Data Source
AI summary
A method may comprise transmitting a first signal derived from a first subset of a set of LDPC coded bits and transmitting a second signal derived from a second subset of the set of LDPC coded bits. The second subset may be selected from the set of LDPC coded bits based on a lifting size of an LDPC base graph. The method may further comprise receiving an indication of a first redundancy version. The transmitting the first signal may be in response to receiving the indication of the first redundancy version.