Polar HARQ Retransmission Using Adaptive Bit-Channel Reliability
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Solution Overview
Problem
Wireless communication systems face challenges in maintaining reliable data transmission over time-varying channels, where decoding errors occur due to changes in channel conditions, leading to performance losses in polar coded HARQ schemes.
Innovation Solution
The implementation of enhanced polar HARQ techniques, where a transmitting device generates and transmits a second set of encoded bits using a larger polar code based on updated channel quality metrics, incorporating copied information bits to improve decoding reliability, and using channel feedback to adjust the number of bits in the retransmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polar coded HARQ schemes are used for wireless communication, then data transmission reliability is improved, but decoding errors occur due to channel variations leading to performance loss
Solution Approach 1:
The patent applies dynamics by making the polar code construction adaptive to changing channel conditions. The bit channel reliability estimates are updated based on current channel quality metrics, allowing the encoding scheme to dynamically adjust to time-varying channels and maintain reliability while reducing decoding errors
Solution Approach 2:
The patent changes the parameter of bit channel reliability estimates based on channel quality metrics. By comparing channel conditions before and after retransmission, the system adjusts the reliability parameters used in polar code construction, thereby adapting to channel variations and reducing performance loss
2Reliability
If channel quality metrics are compared and copied information bits are adjusted, then decoding reliability is improved, but device complexity increases
Solution Approach 1:
The patent implements feedback by comparing channel quality metrics from previous transmissions with current channel conditions. This feedback mechanism allows the system to adjust the number of copied information bits based on actual channel variations, improving decoding reliability while maintaining manageable complexity through rule-based adjustments
3Reliability
If a second set of encoded bits is generated using a larger polar code, then decoding reliability is improved, but transmission overhead increases
Solution Approach 1:
The patent applies partial action by selectively copying only the necessary number of information bits based on channel conditions. Instead of always using the maximum redundancy, the system adjusts the amount of copied information proportionally to the channel degradation, reducing unnecessary transmission overhead while maintaining sufficient decoding reliability
Data Source
AI summary
A device may generate a first set of encoded bits by mapping an information bit vector to a first set of polarized bit channels of a first polar code according to a first bit index set, the first bit index set being based on respective bit channel reliabilities of the first set of polarized bit channels. The device may transmit the first set of encoded bits to another device over a wireless channel. The device may receive an indication that a decoding of the first set of encoded bits was unsuccessful. The device may generate a second set of encoded bits by mapping a repetition of at least one bit to at least one bit channel of a second set of polarized bit channels of a second polar code according to a second bit index set. The device may transmit the second set of encoded bits to the other device.