S-Random Interleaver Pruning for Flexible Block Lengths
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Solution Overview
Problem
Conventional pruning techniques for S-random interleavers often destroy their spread properties, limiting flexibility in block length and code-rate modifications, and are not suitable for a wide range of interleaver sizes.
Innovation Solution
A new pruning method that selectively adds or removes positions in S-random interleavers to maintain improved spread properties, using incremental techniques and vector-based algorithms to optimize interleaver generation and reduction, allowing for a wider range of interleaver sizes with enhanced spreading properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If conventional pruning techniques are used to reduce interleaver size, then memory requirements are reduced, but spread properties are destroyed
Solution Approach 1:
The patent extracts only the necessary elements from the initial interleaver by using a selection criterion based on position indices. Instead of randomly or arbitrarily removing elements, it systematically selects which elements to keep (those with position indices less than the target size K) and which to discard, thereby reducing memory requirements while preserving the essential spread properties of the interleaver.
Solution Approach 2:
The patent changes the parameter of interleaver size from N to K by applying a pruning operation. This parameter change is achieved through a systematic selection process that maintains the spread properties by ensuring that the remaining elements after pruning still satisfy the S-random interleaver conditions, thus resolving the contradiction between size reduction and property preservation.
2Adaptability or versatility
If conventional pruning techniques are used to reduce interleaver size, then flexibility in block length is improved, but spread properties deteriorate
Solution Approach 1:
The patent introduces a dynamic pruning process that can adapt to different target sizes K. The selection criterion dynamically adjusts based on the desired output size, allowing the system to maintain optimal spread properties across a range of block lengths. This dynamic approach enables flexibility in block length while preserving the essential characteristics of S-random interleavers through the position-index-based selection method.
3Adaptability or versatility
If a larger initial interleaver is used to support multiple sizes, then adaptability is improved, but memory requirements increase
Solution Approach 1:
The patent segments the initial interleaver of size N into a smaller pruned interleaver of size K by applying a selection criterion. This segmentation allows the system to store only one initial interleaver in memory while generating multiple smaller interleavers on-demand through the pruning process, thus reducing memory requirements while maintaining adaptability across different block lengths.
Solution Approach 2:
The patent makes a single initial interleaver universal by enabling it to serve multiple purposes through the pruning operation. The same initial interleaver can be pruned to different sizes K to support various block lengths and code rates, eliminating the need to store multiple separate interleavers and thereby reducing memory requirements while maintaining versatility.
Data Source
AI summary
A system, method and machine-readable medium for pruning an S-random interleaver starting with an interleaver permutation having N elements and alternating between invalidating the last element of the interleaver permutation and invalidating the last element of a corresponding inverse interleaver permutation until the interleaver permutation has K elements, K being less than N, the method being characterized by the use of a reference vector having N flags and comprising: storing a value in an element of the reference vector corresponding to the value of the each element invalidated in the interleaver permutation.