Polar Code Rate Matching for Low-Overhead Wireless Encoding
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Solution Overview
Problem
Polar codes face challenges in rate matching, leading to increased complexity and overhead during encoding and decoding, especially when adjusting code lengths from a mother code to a target code, which affects encoding gain and decoding delays.
Innovation Solution
A method for polar code rate matching that involves using a mother code length less than or equal to the target code length and repeating bits when necessary, or using a longer mother code and shortening/puncturing when the target code is shorter, to achieve a balanced encoding gain and reduced complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If puncturing or shortening is used for rate matching to reduce mother code length, then complexity and buffer sizes are reduced, but additional overheads increase significantly
Solution Approach 1:
The patent performs rate matching by repeating or shortening/puncturing the mother code before encoding, rather than after. This preliminary rate matching allows the encoder to work with a code length closer to the target length, reducing the number of bits that need to be shortened or punctured afterward, thereby reducing overhead while maintaining low complexity
Solution Approach 2:
The patent dynamically adjusts the mother code length based on the target code length and communication conditions. By selecting an appropriate mother code length from a set of possible lengths, the system can optimize the balance between complexity and overhead for different transmission scenarios
2Reliability
If mother code length is increased to reduce rate matching overhead, then encoding gain improves, but complexity and decoding delays increase
Solution Approach 1:
The patent changes the parameter of mother code length to be adaptive rather than fixed. By selecting from multiple possible mother code lengths based on target code length and channel conditions, the system can achieve good encoding gain when needed while avoiding excessive complexity by using shorter mother codes when appropriate
3Adaptability or versatility
If puncturing or shortening is applied to achieve target code length from mother code, then rate matching is achieved, but decoding delays increase
Solution Approach 1:
The patent performs rate matching operations before encoding rather than after. This allows the decoder to know in advance the effective code length and structure, enabling it to prepare appropriate decoding parameters and buffers beforehand, thus reducing decoding delays while maintaining flexible rate matching capability
Data Source
AI summary
Embodiments of the application provide a method for rate matching in a wireless communication network. A device obtains K information bits and a target code length M of a polar code, determines, according to a minimum value of a set of values, a mother code length N1, polar encodes the K information bits to obtain an encoded sequence of N1 bits, obtains a target sequence of M bits from the N1 bit encoded sequence, and outputs the M-bit target sequence. When the mother code length N1 is larger than the target code length M, (N1−M) bits of the encoded sequence are punctured or shortened from the N1 bit encoded sequence.