Polar HARQ Retransmission Using Variable Code Size and Copied Bits
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Solution Overview
Problem
Wireless communication systems face challenges in reliably decoding information bits during retransmissions due to varying channel conditions and interference, especially when using polar coding with hybrid automatic repeat request (HARQ) operations, as existing techniques do not effectively adapt to changes in channel conditions or transmission parameters.
Innovation Solution
The implementation of enhanced polar HARQ operation techniques, where a transmitting device generates and transmits second encoded bits using a larger polar code size, incorporating copied information bits based on changing channel conditions or transmission parameters, along with an indication of the number of copied bits, to improve decoding reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed-size polar code is used for retransmission, then the transmission protocol is simple, but the decoding reliability cannot adapt to changing channel conditions
Solution Approach 1:
The patent implements dynamic code size adjustment in polar HARQ retransmissions. The transmitter adapts the polar code size (N, 2N, 4N, etc.) based on channel conditions and transmission parameters. This allows the system to transition from fixed-size to variable-size coding, improving decoding reliability under varying channel conditions while maintaining protocol simplicity through standardized adaptation rules.
Solution Approach 2:
The patent changes the code size parameter of the polar code based on channel conditions and transmission parameters. By adjusting the code size parameter dynamically, the system optimizes the balance between error correction capability and transmission efficiency, resolving the contradiction between reliability and complexity.
2Reliability
If larger polar code size is used for retransmission, then decoding reliability improves, but transmission overhead increases
Solution Approach 1:
The patent applies partial action by transmitting only the necessary number of encoded bits for retransmission. Instead of always transmitting full codewords of size 2N or 4N, the system transmits a partial codeword containing sufficient information for successful decoding, reducing transmission overhead while maintaining improved reliability through adaptive code size selection.
Solution Approach 2:
The system dynamically adjusts the code size and corresponding transmission overhead based on channel conditions. When channel conditions are good, smaller code sizes are used reducing overhead. When conditions deteriorate, larger code sizes provide better reliability. This dynamic adaptation resolves the contradiction between reliability improvement and overhead increase.
3Reliability
If copied information bits are used to generate retransmission, then decoding success rate increases, but the receiving device needs additional information about the number of copied bits
Solution Approach 1:
The patent implements feedback mechanisms where the transmitter informs the receiver about the number of copied information bits used in generating the retransmission. This feedback enables the receiver to correctly combine the original and retransmitted signals, improving decoding success rate while preventing information loss through proper communication of copying parameters.
Data Source
AI summary
Methods, systems, and devices are described for wireless communications. A transmitting device may generate first encoded bits by encoding first information bits using a polar code of a first size, N, and transmit the first encoded bits to a receiving device. After determining the receiving device failed to decode the encoded bits, the transmitting device may generate second encoded bits by encoding the first information bits using a polar code of a second size, 2N. In some cases, the transmitting device may use the first encoded bits and one or more copied information bits to generate the second encoded bits. The transmitting device may transmit the second encoded bits to the receiving device, along with an indication of the number of copied information bits used to generate the second encoded bits. The number of copied information bits may be based on changing channel conditions or transmission parameters.