Polar Code HARQ With Random Length and Bit Position Optimization
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Solution Overview
Problem
Current polar codes for wireless communications do not effectively achieve random lengths optimized for mutual information, limiting their performance in physical layer security and Hybrid Automatic Repeat Request (HARQ) schemes, which are crucial for reliable and secure data transmission.
Innovation Solution
A method involving puncturing a mother code to generate a second code with a different length, optimizing the locations of information and non-information bits based on mutual information calculations using log likelihood ratios, and applying these optimizations to perform HARQ, while utilizing Gaussian approximation to minimize information loss and maximize variance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If polar codes with fixed lengths (powers of 2) are used, then the code construction is simple and standardized, but the adaptability to different communication scenarios and optimization of mutual information is limited
Solution Approach 1:
The patent applies dynamics by enabling the polar code length to be dynamically adjusted to any integer value rather than being fixed to powers of 2. This is achieved through a flexible code construction method that can adapt the code length according to different communication scenario requirements, thereby resolving the contradiction between adaptability and construction complexity
Solution Approach 2:
The patent changes the parameter of code length from discrete values (powers of 2) to continuous integer values. By modifying this fundamental parameter, the system achieves better adaptability to different communication scenarios while maintaining reasonable construction complexity through systematic code generation methods
2Reliability
If conventional ARQ schemes are used, then the implementation is simple, but the communication reliability and efficiency are insufficient due to packet discarding
Solution Approach 1:
The patent applies the discarding and recovering principle by preventing the discarding of erroneous packets. Instead, the system recovers from errors through HARQ combining, where erroneous packets are retained and combined with retransmitted packets to recover the original data, thereby improving reliability without excessive complexity
Solution Approach 2:
The patent implements feedback mechanisms through HARQ protocols where the receiver provides feedback about packet reception status. This feedback enables the transmitter to retransmit or send parity bits as needed, improving communication reliability through iterative error correction while managing protocol complexity systematically
3Reliability
If cryptography-based security is used, then the security strength can be sufficient, but the key generation, distribution, and management become complex and time-consuming
Solution Approach 1:
The patent extracts the security function from the complex cryptographic key management system and implements it directly at the physical layer through polar code construction. By taking out the security mechanism from upper-layer cryptography and embedding it in the channel coding structure, the system achieves security without the complexity of key generation, distribution, and management
Solution Approach 2:
The patent uses polar codes as an intermediary mechanism that provides security functionality without requiring traditional cryptographic key management. The polar code structure itself acts as a mediator that enables secure communication through its inherent error correction and information theoretic security properties, eliminating the need for separate key management infrastructure
4Measurement precision
If polar codes with random lengths are used, then the optimization of mutual information and adaptability improve, but the code construction complexity increases
Solution Approach 1:
The patent applies dynamics by enabling the polar code length to be dynamically adjusted to any integer value rather than being fixed to powers of 2. This is achieved through a flexible code construction method that can adapt the code length according to different communication scenario requirements, thereby resolving the contradiction between adaptability and construction complexity
Solution Approach 2:
The patent changes the parameter of code length from discrete values (powers of 2) to continuous integer values. By modifying this fundamental parameter, the system achieves better adaptability to different communication scenarios while maintaining reasonable construction complexity through systematic code generation methods
Data Source
AI summary
The present specification provides a method for performing a physical layer security-based hybrid automatic repeat request (HARQ). The method comprises the steps of: generating a first code comprising information bits for forming data to be transmitted, and non-information bits which are unrelated to the data to be transmitted; generating a second code, having a length which differs from that of the first code, by puncturing the first code; determining locations of the information bits and non-information bits within the second code such that a variance of mutual information for each of the information bits and the non-information bits is maximized; and performing the HARQ by using the second code in which the locations of the information bits and the non-information bits are determined.