HARQ Retransmission Encoding With Flexible Code Length Extension
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Solution Overview
Problem
Current hybrid automatic repeat request (HARQ) technologies, such as chase combining (CC-HARQ), incremental freezing (IF-HARQ), and incremental redundancy (IR-HARQ, face limitations in flexibility and coding gain, particularly in extending code length and managing retransmissions effectively.
Innovation Solution
A retransmission method that involves obtaining a first bit sequence through initial channel encoding of information bits, followed by secondary channel encoding to generate a sequence for retransmission, using an extended matrix that can adapt to varying numbers of to-be-retransmitted bits, allowing for flexible code length extension and improved decoding reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If IR-HARQ extends code length to improve performance, then coding gain is achieved, but the application becomes inflexible due to irregular reading and duplication of information bits
Solution Approach 1:
The patent implements dynamic code length extension by allowing the extended code length to be flexibly configured based on retransmission requirements. The system can adaptively determine the number of extended bits (E) and use an extended matrix with configurable dimensions (E rows × N columns) to generate retransmission bit sequences of varying lengths, enabling flexible adaptation to different channel conditions and retransmission scenarios while maintaining coding gain.
Solution Approach 2:
The patent changes the parameter of code length from fixed to variable by introducing an extended code length parameter (N+E) where E can be dynamically adjusted. The extended matrix parameters (E rows, N columns) are configurable to match different retransmission needs. This parameter flexibility allows the system to optimize coding gain while adapting to various transmission scenarios without being constrained by fixed code length structures.
2Ease of manufacture
If CC-HARQ is used for retransmission, then implementation is simple, but no coding gain is generated
Solution Approach 1:
The patent segments the encoding process into two distinct parts: initial encoding (first channel encoding) and retransmission encoding (second channel encoding using extended matrix). This segmentation allows the system to maintain the simplicity of basic HARQ implementation while adding an optional extended encoding stage that provides coding gain. The separated structure enables flexible deployment where the extended encoding can be applied selectively based on retransmission needs.
Solution Approach 2:
The patent performs preliminary extended encoding preparation by pre-defining the extended matrix structure and parameters before actual retransmission occurs. The extended matrix (E rows × N columns) and extended base matrix are prepared in advance, allowing the system to quickly generate retransmission bit sequences with coding gain when needed, without adding significant complexity to the real-time retransmission process.
3Reliability
If IF-HARQ is used for retransmission, then coding gain is achieved, but decoding delay and encoding/decoding complexity increase
Solution Approach 1:
The extended matrix serves multiple functions: it acts as both an encoding matrix for generating retransmission bit sequences and as a basis for efficient decoding operations. The extended base matrix can be configured to work with different code lengths and retransmission scenarios, providing a universal solution that achieves coding gain without requiring separate complex encoding and decoding structures. This multi-functionality reduces overall system complexity while maintaining coding gain benefits.
Data Source
AI summary
This application discloses a retransmission method and an apparatus. The method includes: obtaining a first bit sequence and a number E of to-be-retransmitted bits, performing second channel encoding based on the first bit sequence to obtain a second bit sequence, and performing retransmission based on the second bit sequence. The first bit sequence is obtained by performing first channel encoding based on K information bits, a length of the first bit sequence is N, N, E, and K are all integers greater than or equal to 1, and the second bit sequence includes the E to-be-retransmitted bits. According to the method, a code length can be flexibly extended based on different numbers E of to-be-retransmitted bits.