Polar-Code HARQ Retransmission Using Interleaved Re-Encoding
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Solution Overview
Problem
In communication systems, especially those using polar codes, there is a need for efficient signal retransmission methods to improve transmission and reception performance, particularly in scenarios with high error probabilities due to overcrowded channels, such as in Narrowband-IoT services, where traditional error correction codes like LDPC and turbo codes are less effective for short data transmissions.
Innovation Solution
The implementation of a hybrid automatic repeat request (HARQ) scheme using polar codes, where a transmitting node encodes information bits using polar encoders and modulates them for initial and retransmission signals, with interleaving and different polar encoders used for each transmission round to enhance error correction and decoding performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional error correction codes (LDPC or turbo codes) are used for short data transmissions, then the encoding performance is insufficient, but using polar codes improves error correction capability while requiring more complex encoding and decoding processes
Solution Approach 1:
The information bits are divided into multiple groups that are processed through different polar encoders with distinct generator matrices. This segmentation allows the system to leverage the error correction strengths of polar codes while managing complexity through modular processing of bit groups rather than treating all bits uniformly.
Solution Approach 2:
Different polar encoders with different generator matrices are assigned to different groups of information bits based on their reliability requirements. This local quality approach optimizes error correction for specific bit positions while maintaining overall system performance, rather than applying a single uniform encoding scheme to all bits.
2Reliability
If polar codes are used for short data transmissions in NB-IoT, then communication performance is improved, but the system requires efficient HARQ schemes to handle retransmissions in overcrowded channels
Solution Approach 1:
The system dynamically selects between different polar encoders and their corresponding generator matrices based on channel conditions and transmission round number. This dynamic adaptation allows the HARQ scheme to optimize performance for each retransmission attempt, improving productivity by adapting to changing channel conditions rather than using a static encoding scheme.
Solution Approach 2:
The generator matrix parameters of the polar encoders are changed between different transmission rounds. By varying the encoder parameters dynamically, the system can overcome channel fading and interference patterns, improving retransmission efficiency while maintaining the reliability benefits of polar codes in overcrowded NB-IoT channels.
Data Source
AI summary
An operation method of a transmitting node in a communication system may comprise:generating 2N initial transmission bits by encoding N information bits to be transmitted to a receiving node of the communication system in a polar coding scheme; transmitting, to the receiving node, an initial transmission signal generated by modulating the 2N initial transmission bits; receiving, from the receiving node, a signal indicating that the initial transmission signal is not normally received; interleaving the N information bits through an interleaver to generate N interleaved bits; generating 2N first retransmission bits by encoding the N interleaved bits in the polar coding scheme; and transmitting, to the receiving node, a first retransmission signal generated by modulating the 2N first retransmission bits.