Polar Code Circular Buffering for Flexible Rate Matching
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Solution Overview
Problem
Conventional polar codes require codeword lengths to be a power of two, leading to inefficiencies in puncturing and repetition processes for achieving desired codeword lengths, which increases latency, power consumption, and hardware requirements.
Innovation Solution
Implementing a rate-matching mechanism using circular buffering of polar encoded bits, where the interleaver and bit-extractor are dependent on link and system parameters to optimize the ordering and extraction of coded bits, allowing for flexible codeword lengths and improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional polar codes with power-of-two codeword lengths are used, then the coding structure is simple and hardware implementation is straightforward, but the system cannot achieve desired codeword lengths with fine granularity and requires excessive puncturing or repetition
Solution Approach 1:
The codeword is segmented into information bits and frozen bits, with the information bits further divided into groups that can be selectively punctured. This segmentation allows flexible rate-matching by controlling which segments are transmitted, enabling arbitrary codeword lengths while maintaining a simple base coding structure.
Solution Approach 2:
The code is designed with pre-defined information bit groups and freezing patterns that are prepared in advance. This preliminary structuring of the code allows the system to achieve any desired codeword length by simply selecting which pre-defined groups to transmit, without requiring complex real-time processing.
2Adaptability or versatility
If puncturing is performed to achieve desired codeword lengths, then codeword length granularity is improved, but latency and power consumption increase
Solution Approach 1:
The information bits are pre-grouped into sets corresponding to different target codeword lengths. When a specific codeword length is needed, the system simply selects the corresponding pre-grouped bits for transmission, eliminating the need for complex real-time puncturing decisions and reducing processing latency.
Solution Approach 2:
The system changes the transmission parameter (number of information bits transmitted) in discrete steps corresponding to different codeword lengths. By pre-defining these parameter values and their corresponding bit groupings, the system can quickly switch between different codeword lengths without complex intermediate processing.
3Adaptability or versatility
If repetition is used to achieve desired codeword lengths, then the required processing speed and memory are increased, but codeword length flexibility is improved
Solution Approach 1:
The code structure segments information bits into groups that can be transmitted in different quantities. Instead of generating a full power-of-two codeword and repeating it, the system transmits only the required number of information bit groups, reducing the total number of bits to be processed and transmitted while maintaining codeword length flexibility.
4Device complexity
If power-of-two codeword lengths are enforced, then hardware requirements are simplified, but system performance is degraded due to excessive puncturing or repetition
Solution Approach 1:
The code segments information bits into groups that align with the polar code structure. This segmentation allows the system to transmit an optimal number of information bits that matches the channel conditions and desired codeword length, avoiding the performance degradation caused by excessive puncturing or repetition while keeping hardware requirements manageable.
Data Source
AI summary
Methods are proposed herein to perform rate matching for polar codes via circular buffering of the polar encoded bits. Embodiments are directed to methods of operation of a transmitting node in a wireless system including performing polar encoding of a set of information bits in accordance with a polar sequence of length NB to thereby generate NB coded bits. The method can further include interleaving the coded bits to thereby provide an interleaved coded bit sequence, and storing the interleaved coded bit sequence into a circular buffer of length NB. According to certain embodiments, the method can further include extracting N coded bits for transmission from the circular buffer. N can be greater than, equal to, or less than NB.