Viterbi Decoder State Constraints for Known Padding Bits
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Solution Overview
Problem
Conventional forward error correction schemes in communications networks are inefficient when dealing with known padding bits, as they perform redundant encoding and decoding operations, increasing the probability of errors during data decoding due to unawareness of padding bits.
Innovation Solution
The method involves constraining the start and/or end state of the Viterbi decoder using known padding bits to skip over decoding of padding bits, thereby improving decoding accuracy by only processing actual data bits and pruning erroneous paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional forward error correction schemes are used to encode and decode the entire data block including padding bits, then the decoding process is simplified and more uniform, but the probability of decoding errors increases and decoding efficiency decreases due to redundant operations on known padding bits
Solution Approach 1:
The data block is segmented into two distinct parts: known padding bits and unknown data bits. The Viterbi decoder is configured to process only the unknown data bits segment, excluding the known padding bits from decoding operations. This segmentation eliminates redundant decoding of padding bits while maintaining proper error correction for the actual data, thereby improving both decode success rate and decoding efficiency.
Solution Approach 2:
The positions and values of padding bits are determined in advance before the decoding process. This preliminary knowledge is utilized to constrain the Viterbi decoder to skip over the padding bit positions and directly decode only the unknown data bits. By performing this preliminary identification and using it to guide the decoding process, the system avoids redundant operations and improves decoding efficiency without compromising reliability.
2Ease of manufacture
If the entire data block including known padding bits is subjected to encoding and decoding operations, then the forward error correction process remains uniform and simple to implement, but redundant encoding and decoding operations increase the probability of errored data decoding
Solution Approach 1:
Different parts of the data block are treated with different quality of processing. The known padding bits are excluded from the decoding process entirely, while the unknown data bits receive full Viterbi decoding treatment. This local differentiation in processing quality ensures that redundant operations on known bits are eliminated, thereby improving decode accuracy without significantly complicating the overall implementation.
Solution Approach 2:
The known padding bits are extracted and separated from the data block before the decoding process. By removing these known bits from the decoding input, the Viterbi decoder operates only on the unknown data bits, eliminating the source of redundant operations that could lead to decoding errors. This extraction approach maintains implementation simplicity while improving reliability.
Data Source
AI summary
A method and system of decoding a convolutionally encoded data block having known padding bits. A Viterbi decoder is constrained to a state corresponding to k−1 padding bits immediately adjacent to data bits of the data block, where k is a constraint length of a convolution encoder used to encode the data block. Symbols of the encoded data block that have influence only from the padding bits are discarded.