Polar Code Rate Matching for Low-Latency URLLC Reliability
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Solution Overview
Problem
Current 5G mobile communication technologies face challenges in achieving high reliability and low latency for Ultra Reliable and Low Latency Communications (URLLC) due to inefficiencies in spectral allocation and error rate guarantees, particularly in hybrid ARQ schemes, which result in suboptimal performance under varying interference and fading conditions.
Innovation Solution
The implementation of polar codes with adaptive mother code lengths and interleaving techniques, such as part-wise and global interleaving, to enhance reliability and efficiency in URLLC transmissions, allowing for better resource allocation and error correction, particularly through the use of circular buffers and rate matching schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hybrid ARQ schemes are used for error correction, then reliability is improved, but latency increases due to retransmissions under varying interference and fading conditions
Solution Approach 1:
The patent implements dynamic rate matching and adaptive code rate selection based on channel conditions. The system adjusts the code rate and redundancy version dynamically for each transmission, allowing optimal balance between reliability and latency without fixed retransmission schemes. This dynamic adaptation eliminates the need for conservative hybrid ARQ retransmissions while maintaining error rate guarantees.
Solution Approach 2:
The patent changes key parameters including code rate, mother code length, and redundancy version based on channel quality indicators. By varying these parameters adaptively, the system achieves high reliability in poor conditions without incurring latency penalties, as the parameters are optimized before transmission rather than requiring post-transmission retransmissions.
2Ease of manufacture
If polar codes with fixed mother code length are used, then encoding simplicity is maintained, but spectral efficiency deteriorates under varying channel conditions
Solution Approach 1:
The patent introduces dynamic mother code length selection and adaptive rate matching that adjusts the effective code length based on channel conditions and payload size. This maintains the simplicity of polar code structure while achieving variable spectral efficiency through parameter adaptation, allowing the system to optimize resource utilization without complex encoding schemes.
Solution Approach 2:
The system varies the mother code length and code rate as adjustable parameters based on channel quality and traffic requirements. This allows the same polar code framework to achieve high spectral efficiency in good conditions while maintaining robustness in poor conditions, all without changing the fundamental encoding algorithm.
3Productivity
If higher code rates are used to increase data rate, then productivity is improved, but reliability deteriorates due to reduced redundancy for error correction
Solution Approach 1:
The patent implements dynamic redundancy allocation where the amount of redundancy is adjusted based on real-time channel conditions. When channel quality is good, the system uses higher code rates with minimal redundancy for maximum throughput. When conditions deteriorate, redundancy is increased dynamically to maintain reliability, achieving an optimal trade-off at each transmission instance.
Solution Approach 2:
The system performs preliminary channel quality assessment and pre-calculates the optimal code rate and redundancy level before transmission. This preliminary action ensures that the appropriate balance between data rate and error correction is established in advance, eliminating the need for conservative low-rate transmissions that would require retransmissions.
4Reliability
If more redundancy bits are added to improve error correction, then reliability is improved, but spectral efficiency decreases due to increased overhead
Solution Approach 1:
The patent varies the redundancy level as a dynamic parameter based on channel conditions and payload characteristics. Instead of fixed redundancy overhead, the system adjusts the redundancy fraction adaptively, using minimal redundancy when channel quality is high and increasing redundancy only when necessary to meet reliability targets, thereby maximizing spectral efficiency across varying conditions.
Data Source
AI summary
Systems, procedures, and instrumentalities are disclosed for transmissions with polar codes. A transmitting entity may determine a mother code length. The mother code length may be based on value(s), e.g., a maximum number of transmissions. The transmitting entity may determine a number of information bits to be polar encoded. The number of information bits may be larger than a number of payload bits. The transmitting entity may map the number of information bits to a number of bit channels of a polar code. The transmitting entity may polar encode the information bits in the bit channels using the determined mother code length. The transmitting entity may partition the polar encoded bits into a number of parts. The number of parts may be based on one or more values, e.g., the maximum number of transmissions. The transmitting entity may transmit bits that have been interleaved to a circular buffer.