Systematic Polar Coding for Non-Uniform JSCC Decoding
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Solution Overview
Problem
Wireless communications systems face challenges in decoding non-uniform sources due to the limited capabilities of successive cancellation list decoders, which struggle with non-uniform bit distributions introduced by residual redundancy after source coding, leading to decreased decoder performance.
Innovation Solution
Applying systematic polar codes to non-uniform sources, where a first wireless device generates a systematic polar codeword with parity and systematic bits, and may puncture systematic bits for transmission, allowing a second wireless device to decode using LLRs associated with parity and punctured systematic bits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If successive cancellation list decoders are used to decode non-uniform sources, then the decoder structure is maintained and operation is simplified, but decoding performance deteriorates due to limited capability to handle non-uniform bit distributions
Solution Approach 1:
The codeword is segmented into systematic bits and parity bits, where systematic bits carry the original information and parity bits provide redundancy. This segmentation allows the decoder to handle non-uniform distributions more effectively by treating different bit types differently during the decoding process, improving performance while maintaining the SCL decoder structure.
Solution Approach 2:
The invention changes the parameter representation by using log-likelihood ratios (LLRs) to capture the non-uniform bit distribution characteristics. By transforming the decoding parameters to account for the non-uniform distribution, the SCL decoder can maintain its operational simplicity while achieving improved decoding performance for non-uniform sources.
2Loss of information
If all systematic bits are transmitted along with parity bits, then complete information is available at the receiver, but transmission efficiency decreases due to redundant systematic bits
Solution Approach 1:
The invention extracts and transmits only the parity bits separately from the systematic bits. The systematic bits are retained at the transmitter and not fully transmitted, reducing redundancy. The receiver reconstructs the complete information by combining the received parity bits with the locally stored systematic bits, thereby improving transmission efficiency while maintaining information completeness.
Solution Approach 2:
The parity bits serve as an intermediary that carries the essential information needed for reconstruction. Instead of transmitting all systematic bits directly, the system uses parity bits as a mediator to convey the necessary information, reducing the total transmission load while ensuring the receiver can recover the complete original data.
3Productivity
If systematic bits are punctured to improve transmission efficiency, then transmission bandwidth is reduced, but decoder complexity increases to handle the punctured systematic bits
Solution Approach 1:
The receiver performs preliminary actions by pre-storing the systematic bits before decoding. This preliminary preparation allows the decoder to simply combine the pre-stored systematic bits with the received parity bits without requiring complex puncture detection and reconstruction algorithms, thereby maintaining decoder simplicity while achieving transmission efficiency improvements through systematic bit puncturing.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. In some cases, a first wireless device may communicate, with a second wireless device, a control signal indicating a systematic polar code configuration, the systematic polar code configuration indicating for the first wireless device to perform systematic polar encoding on a first set of bits associated with a non-uniform bit distribution. As such, the first wireless device may apply a systematic polar code to the first set of bits to generate a systematic polar codeword based on the systematic polar code configuration. In such cases, the systematic polar codeword may include a set of parity bits and a set of systematic bits. Thus, the first wireless device may transmit at least the set of parity bits of the systematic polar code.