Apparatus and methods for source coding and channel coding of low entropy signals
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Solution Overview
Problem
Existing source coding and channel coding techniques are inadequate for efficiently handling low entropy signals in wireless communication systems, particularly in scenarios where ACK/NAK signaling involves non-independent and non-equiprobable bits.
Innovation Solution
The proposed solution involves using modified Huffman coding for source coding, which generates variable length codewords with or without a length cap, and applying fixed length channel coding to these codewords after padding with known or pseudo-random sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Huffman coding is used for source coding of low entropy signals, then coding efficiency is improved, but codeword length becomes very large
Solution Approach 1:
The patent segments the source coding and channel coding processes into distinct stages. Source coding (including Huffman coding) is performed first to exploit signal statistics and reduce redundancy, generating variable-length codewords. Then channel coding is applied to these codewords with appropriate padding to achieve reliable transmission. This segmentation allows each coding stage to optimize for its specific purpose without compromising the other.
Solution Approach 2:
The patent employs dynamic codeword length adaptation by using variable-length Huffman codewords that are subsequently padded to fixed lengths suitable for channel coding. The padding length is dynamically adjusted based on the original codeword length and the requirements of the channel code, allowing the system to maintain coding efficiency while meeting transmission constraints.
2Productivity
If variable length source coding is used, then low entropy signal compression is improved, but compatibility with fixed length channel codes deteriorates
Solution Approach 1:
The patent introduces padding sequences as an intermediary mechanism between variable-length source codewords and fixed-length channel codes. These padding sequences (which may be known sequences, pseudo-random sequences, or zero sequences) serve as a bridge that allows variable-length data to be efficiently transmitted through fixed-length channel coding schemes without loss of compression benefits.
Solution Approach 2:
The patent changes the length parameter of codewords by padding variable-length source codewords to fixed lengths that are compatible with channel coding requirements. This parameter transformation maintains the compression efficiency gains from source coding while ensuring compatibility with the fixed-length constraints of channel codes.
3Ease of operation
If individual bits are transmitted for ACK/NAK signaling, then implementation simplicity is improved, but transmission efficiency deteriorates
Solution Approach 1:
The patent merges multiple ACK/NAK bits into grouped representations that exploit the statistical properties of these signaling bits. By grouping and jointly encoding ACK/NAK bits rather than transmitting them individually, the system achieves better transmission efficiency while maintaining implementation feasibility through standardized coding procedures.
Data Source
AI summary
Signaling that indicates information associated with variable length source coding at a first communication device is communicated between a first communication device to a second communication device in a wireless communication network. Variable length source coded data to which channel coding has been applied is also transmitted by the first communication device to the second communication device, and received from the first communication device by the second communication device. This type of source coding approach may be particularly useful for low entropy signals.