Polar Code Channel Segmentation for Secure Transmission Capacity
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Solution Overview
Problem
Existing polar code-based secure communication systems face limitations in transmitting information efficiently due to a limited number of bit channels available for secure data transmission, especially when code length is finite, leading to the presence of gray bit channels that neither error nor always error, complicating the separation into good and bad bit channels.
Innovation Solution
A method is proposed that utilizes a polar code generator matrix to categorize bit channels into good, gray, and bad channels based on mutual information, with specific bit sequences transmitted over these channels to maximize secure data transmission, incorporating techniques like substitution permutation networks (SPNs), dynamic frozen bits, and additional channel codes like MDS codes to enhance security and error correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polar code is used for secure transmission, then transmission rate approaches channel capacity as code length increases, but the number of usable bit channels for secure transmission remains limited when code length is finite
Solution Approach 1:
The patent segments bit channels into three distinct categories (good, gray, and bad channels) based on their error characteristics and mutual information values. This segmentation allows the system to selectively utilize good channels for information transmission while treating gray and bad channels appropriately, thereby maximizing the number of usable channels for secure transmission without compromising security.
Solution Approach 2:
The patent changes the parameter classification criteria from binary (good/bad) to ternary (good/gray/bad) based on mutual information thresholds. By introducing gray channels as an intermediate category with specific mutual information ranges, the system can more finely tune which channels are suitable for secure transmission, increasing the quantity of usable channels while maintaining the approach to channel capacity as code length increases.
2Reliability
If bit channels are separated into good and bad channels, then error correction performance improves, but gray bit channels complicate the separation process
Solution Approach 1:
The patent divides bit channels into three segments (good, gray, bad) rather than two, where each segment has clearly defined mutual information thresholds. This tripartite segmentation maintains the reliability benefits of separating good from bad channels while providing a structured approach to handling gray channels through specific encoding schemes, thus managing complexity through systematic classification.
Solution Approach 2:
The patent applies different quality standards and handling methods to different channel types: good channels receive information bits with high reliability requirements, gray channels use specific encoding schemes appropriate to their intermediate quality, and bad channels are treated with frozen bits or error correction codes. This local quality approach optimizes error correction performance for each channel type while maintaining overall system manageability.
3Loss of information
If more bit channels are utilized for secure transmission, then information transmission amount increases, but security against eavesdroppers may be compromised
Solution Approach 1:
The patent changes the security parameter by classifying channels based on mutual information thresholds that account for both legitimate receiver and eavesdropper channel qualities. By identifying good channels where the legitimate receiver has significantly higher mutual information than the eavesdropper, the system increases information transmission amount while maintaining security through the inherent mutual information gap.
Solution Approach 2:
The patent uses mutual information as an intermediary metric to balance information transmission amount and security. By calculating and comparing mutual information values for both good and gray channels considering eavesdropper presence, the system can selectively activate channels that provide adequate security margin, thus increasing overall transmission amount without compromising security.
Data Source
AI summary
A method and apparatus for providing a secure transmission based on a polar code are provided. A device generates an output bit sequence by applying a polar code generator matrix to an input bit sequence and transmits the output bit sequence to a target receiver. The input bit sequence includes first information bits, second information bits and third information bits. The first information bits correspond to gray bit channels for the target receiver and bad bit channels for an eavesdropper. The third information bits correspond to good bit channels for the target receiver and gray bit channels for the eavesdropper.