Polar Code Rate Matching With Pre-Transforms for Short URLLC Payloads
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Solution Overview
Problem
Current channel coding techniques, such as LDPC codes, are inadequate for short payload sizes and exhibit high error floors, which are not suitable for the demands of future ultra-reliable low latency communication (URLLC) in 5G wireless systems.
Innovation Solution
The proposed solution involves rate matching designs for polar coding, PAC coding, and other pre-transformed polar coding schemes. This includes performing a polar transform with multiple components and applying either no pre-transform or multiple pre-transform operations, based on specific polar matrices, to efficiently match the rate of the channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If LDPC codes are used for channel coding, then the coding structure is simple and implementation is easy, but the error floor is high and performance is inadequate for short payload sizes
Solution Approach 1:
The channel coding process is segmented into multiple distinct stages: pre-transform operation on input bits, polar transform operation, and rate matching operation. This segmentation allows each operation to be optimized independently, with the pre-transform specifically designed to improve error floor performance while keeping the polar transform and rate matching operations computationally efficient
Solution Approach 2:
A pre-transform operation is applied to the input bit sequence before the polar transform operation. This preliminary action modifies the input bits in a way that enhances the overall coding performance and reduces the error floor, without adding significant computational complexity to the main polar coding process
2Adaptability or versatility
If traditional polar coding is used, then the coding rate can be adjusted, but the performance in diverse wireless channel environments is insufficient
Solution Approach 1:
The coding scheme is made dynamic by allowing the pre-transform operation to be selectively applied based on channel conditions and payload size. The system can adapt between applying no pre-transform, one type of pre-transform, or another type of pre-transform, enabling optimal performance across diverse wireless channel environments while maintaining coding rate flexibility
Solution Approach 2:
The invention changes the parameters of the coding scheme by introducing configurable pre-transform operations with different transformation types and parameters. These parameter changes allow the system to optimize performance for specific channel conditions and payload sizes, improving reliability in diverse wireless environments
3Reliability
If multiple pre-transform operations are applied, then the coding performance and reliability are improved, but the computational complexity increases
Solution Approach 1:
Instead of always applying multiple complex pre-transform operations, the system applies partial action by selectively applying one or two specific pre-transform operations only when needed based on channel conditions and payload size. This approach improves reliability when necessary while avoiding unnecessary computational complexity in other scenarios
Data Source
AI summary
Methods, apparatus, and systems that relate to rate matching scheme design for polar coding, PAC coding, or other pre-transformed polar coding are described. One example method includes determining, by a first node, an output bit sequence having E bits based on an input bit sequence having K bits, wherein the output bit sequence is determined by 1) performing a polar transform with H components and 2) performing either no pre-transform or at least two pre-transform operations; wherein the polar transform is based on H polar matrices G(N<sub2>0</sub2>), G(N<sub2>1</sub2>), . . . , G(N<sub2>H−1</sub2>), wherein H, K and E are integers greater than 1, wherein a polar matrix G(N<sub2>i</sub2>) is of size Ni. The method also includes transmitting, by the first node, a signal including the output bit sequence to a second node.