Rateless Polar Coding with Interleaved Bit Selection for IR-HARQ
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Solution Overview
Problem
Existing polar coding schemes require knowledge of code length before transmission, limiting flexibility and impacting reliability, and do not support fine-grained adaptation to varying channel conditions, especially for advanced features like incremental-redundancy hybrid automatic repeat request (IR-HARQ).
Innovation Solution
Implementing rateless polar coding with a unified code construction that allows for flexible code lengths and reduced complexity by interleaving and placing bit values on specific bit indices, enabling encoding and decoding without prior knowledge of code rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional polar coding schemes are used with fixed code length, then code construction is straightforward, but flexibility in adapting to varying channel conditions is limited
Solution Approach 1:
The patent implements dynamic code length selection where the code length is not fixed but can be adjusted based on channel conditions. The encoding process supports variable code lengths by dynamically determining the number of encoded bits to transmit, allowing the system to adapt to varying channel quality without requiring complete code construction redesign for each length.
Solution Approach 2:
The patent changes the code rate parameter dynamically by selecting different numbers of encoded bits to transmit from the same set of generated encoded bits. This allows flexible adaptation to channel conditions by adjusting the effective code rate (ratio of information bits to transmitted bits) without changing the underlying code construction methodology.
2Adaptability or versatility
If rate matching techniques like puncturing and shortening are used, then some flexibility in code rate is achieved, but fine-grained adaptation for advanced features like IR-HARQ is still insufficient
Solution Approach 1:
The patent performs preliminary encoding to generate a complete set of encoded bits for the maximum code length before transmission. Instead of using puncturing or shortening on the generated code, the system selectively transmits a subset of these pre-generated encoded bits based on channel conditions, preserving the integrity of the original code structure while achieving fine-grained rate adaptation.
Solution Approach 2:
The patent extracts and transmits only the necessary number of encoded bits from the full set of generated encoded bits. By selecting and transmitting a subset of encoded bits corresponding to the desired code rate, the system achieves fine-grained flexibility for IR-HARQ while maintaining the reliability benefits of the complete code structure.
3Adaptability or versatility
If code length is determined before transmission, then code construction can be optimized, but ratelessness and true flexibility are compromised
Solution Approach 1:
The patent creates a universal code construction method that can generate encoded bits for any code length up to a maximum length. The same encoding process and bit selection rules are used regardless of the actual transmission length, making the system rateless and truly flexible while maintaining ease of implementation through a single unified construction approach.
Data Source
AI summary
A reduced number of interleaved encoded bits is obtained by encoding input bits by a polar code and interleaving a subset of the encoded bits obtained by the encoding. The polar code comprises a number of bit indices for placing bit values before encoding, including a first set of bit indices for placing values of the input bits and a second set of bit indices for placing a predetermined bit value. The first set of bit indices comprises a first subset of bit indices and a second subset of bit indices. The subset of the encoded bits corresponds to the second subset of the bit indices, and is for reducing the number of the encoded bits. An input bit value placed on both a first bit index in the first subset and a second bit index in the second subset, and the second bit index is based on the interleaving.