Nested Linear Block Encoding for Short-Vector Incremental HARQ
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The conventional Reed-Muller (RM) code in LTE systems has a limited work range and poor performance, particularly not supporting incremental Hybrid Automatic Repeat Request (HARQ) when the information vector length is less than or equal to 5, restricting its application in wireless communication systems.
Innovation Solution
An encoding method that generates a linear block code with a nested structure by reading and combining matrices from a preset code table, allowing for incremental HARQ by adding a unit matrix to the left side of the obtained matrices, thereby expanding the code's work range and improving performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LTE-RM code is used, then the encoding process is simple, but the work range is limited and performance is poor when information vector length is less than or equal to 5
Solution Approach 1:
The encoding process is segmented into two distinct paths based on information vector length: for lengths ≤5, a specialized linear block code with nested structure is used; for lengths >5, the conventional LTE-RM code is used. This segmentation allows optimization for specific short vector lengths without compromising the simplicity for longer vectors.
Solution Approach 2:
The system dynamically selects the encoding method based on the information vector length parameter. When the length is ≤5, it switches to the linear block code with nested structure that supports incremental HARQ; otherwise, it uses the standard LTE-RM code, making the system adaptable to different scenarios.
2Adaptability or versatility
If LTE-RM code is used for short signaling, then the implementation is straightforward, but incremental HARQ is not supported when information vector length is less than or equal to 5
Solution Approach 1:
The linear block code employs a nested structure where generator matrices for different code lengths are nested within each other. The generator matrix G(N,K) contains G(N-L,K-L) as a submatrix, enabling incremental HARQ by allowing the receiver to accumulate soft decisions from previous transmissions and continue decoding with extended code lengths.
Solution Approach 2:
The code parameters (N, K) are changed systematically to create a family of nested codes. By varying the code length and information bit length while maintaining the nested structure, the system achieves incremental HARQ capability for short vectors without requiring completely different code structures.
3Adaptability or versatility
If the code work range is expanded to support shorter vectors, then incremental HARQ can be supported, but the encoding process becomes more complex
Solution Approach 1:
The work range is segmented into two regions: short vectors (length ≤5) handled by the linear block code with nested structure, and longer vectors (length >5) handled by the conventional LTE-RM code. This segmentation expands the overall work range while maintaining encoding simplicity for the majority of cases.
Solution Approach 2:
The linear block code with nested structure serves multiple functions: it provides error correction for short vectors, supports incremental HARQ, and maintains compatibility with the overall LTE signaling framework. This multi-functionality justifies the increased complexity for this specific code family.
Data Source
AI summary
An encoding method includes, when a first code rate K/Nmax is less than or equal to a code rate threshold Rt, reading a first matrix from a preset code table based on a second matrix. The second matrix includes a matrix that is read from the preset code table and that corresponds to a maximum supported code length Nmax and Rt, where K is an integer and N is an integer. The method also includes reading K rows and (N−K) columns starting from a preset first location in the first matrix to obtain a third matrix. The method further includes adding a unit matrix with K rows and K columns to a left side of the third matrix to obtain a generator matrix of an (N, K) linear block code. K rows and (Nmax−Nmax×Rt) columns of the second matrix in a first direction are consistent with K rows and (Nmax−Nmax×Rt) columns of the first matrix in a second direction.