Binary Block Compression Using Combinatorial Index Encoding
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Solution Overview
Problem
Existing methods for acknowledging packet receipt in satellite communications, such as cyclic redundancy check and run-length encoding, are inefficient when error patterns are randomly distributed, as they are not optimized for Rician fading environments, leading to suboptimal compression of acknowledgement words.
Innovation Solution
A method that assigns fewer than N bits to specific patterns of K polarity values in N bits by calculating a base value and displacement value, allowing for efficient encoding and decoding of acknowledgement words, even in environments with random error distributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If run-length encoding is used to compress acknowledgement words, then compression efficiency is improved for clumped error patterns, but performance deteriorates when errors are randomly distributed as in satellite communications
Solution Approach 1:
The patent changes the encoding parameter from run-length representation to combinatorial index representation. Instead of encoding the length of consecutive identical values, the system calculates a combinatorial index based on the position of transitions between 0s and 1s in the acknowledgement word. This parameter change makes the encoding equally efficient for both clumped and random error patterns.
Solution Approach 2:
The patent introduces a dynamic encoding approach that adapts to the actual error pattern distribution. The combinatorial index calculation dynamically adjusts based on the number and position of transitions in the acknowledgement word, rather than assuming a fixed error pattern structure. This dynamic adaptation optimizes compression for the actual observed error distribution.
2Reliability
If the entire acknowledgement word is transmitted with CRC code, then error protection is improved, but transmission bandwidth is wasted due to insufficient compression
Solution Approach 1:
The patent extracts only the essential information from the full acknowledgement word for transmission. Instead of transmitting all N bits, the system calculates a combinatorial index that represents the error pattern using far fewer bits. This extraction of essential information maintains error protection capabilities while dramatically reducing the number of bits that need to be transmitted.
Solution Approach 2:
The patent uses partial action by transmitting only the combinatorial index rather than the complete acknowledgement word. This partial representation is sufficient to convey the error pattern information needed for reliable communication, avoiding the excessive transmission of redundant bits that would be present in full acknowledgement word transmission.
3Productivity
If fewer than N bits are assigned to represent error patterns, then transmission efficiency is improved, but encoding complexity increases due to combinatorial calculations
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing combinatorial values in a lookup table before actual encoding operations. The triangular array of combinatorial values is computed in advance, allowing the encoding process to simply retrieve pre-computed values rather than performing complex calculations in real-time. This preliminary preparation significantly reduces the computational complexity during actual encoding operations.
Data Source
AI summary
Method and apparatus are configured to assign a code of less than N number of bits in length to a pattern of bits of a first polarity value distributed within a block of N binary bits. The method basically comprises (1) determining a number of bits of the first value in the block of N binary bits; (2) selecting a base value based on the determined number of bits of the first value; (3) determining a displacement value representative of a particular distribution of the determined number of bits of the first value in the block of N binary bits; and (4) adding the base value and the displacement value to obtain a sum and using the sum to form an assigned code. The base value is preferably selected by evaluating an Expression Io=NC1+NC2+NC3 . . . +NCK−1, wherein K is the determined number of bits of the first value in the block of N binary bits. Determining the displacement value preferably comprises (if bit N is a binary first value bit), recursively determining the displacement value I(N,K) as N−1CK+I(N−1,K−1), where I(N−1,K−1) is the encoding of the pattern of K−1 number of remaining first value bits in N−1 bits. On the other hand, if bit N is not a first value bit, determining the displacement value preferably comprises recursively determining the displacement value I(N,K) as I(N−1,K) where K is the encoding of the pattern of K number of first value bits in the remaining N−1 number of bits.