Wireless Data Retransmission Using Interleaved LDPC Codewords
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Solution Overview
Problem
Current wireless network systems face challenges in achieving high data rates and reliability, particularly as channel error rates increase, affecting the throughput of Automatic Repeat Request (ARQ) methods but not substantially impacting Forward Error Correction (FEC) methods.
Innovation Solution
The proposed solution involves a method that segments information bits into blocks, encodes them using Low Density Parity Check (LDPC) encoding, and transmits these codewords. Upon receiving feedback indicating unsuccessful decoding, the method interleaves the corresponding information bits, re-encodes them using LDPC, and re-transmits the interleaved codewords.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ARQ methods are used for data transmission, then reliability is improved through error detection and retransmission, but throughput decreases as channel error rate increases
Solution Approach 1:
The patent applies Forward Error Correction (FEC) encoding to data packets before transmission, enabling the receiver to correct errors without requiring retransmission. This preliminary error correction action prevents the throughput degradation that normally occurs with ARQ retransmissions in high error rate channels
Solution Approach 2:
The patent implements a feedback mechanism where the receiver sends acknowledgment packets to the transmitter about decoding success or failure. This feedback enables the transmitter to apply Hybrid ARQ, combining FEC with selective retransmission only when necessary, thus maintaining high throughput while ensuring reliability
2Reliability
If conventional retransmission methods are used, then decoding reliability is improved, but trapping sets reduce retransmission efficiency
Solution Approach 1:
Instead of retransmitting the same codeword that failed to decode, the patent inverts the approach by generating a new codeword from the same information bits using a different LDPC generator matrix. This inversion breaks the trapping set patterns that cause repeated decoding failures, thereby improving retransmission efficiency while maintaining decoding reliability
Data Source
AI summary
Methods and devices are disclosed for transmitting data, including segmenting a group of information bits into a set of information blocks that each include a respective plurality of the information bits; encoding, using low density parity check (LDPC) encoding, each of the information blocks to generate corresponding codewords; transmitting the codewords to a destination station; receiving a feedback message indicating that at least one of the codewords has not been successfully decoded by the destination station; interleaving the information bits of the information block that corresponds to the at least one of the codewords; encoding, using low density parity check (LDPC) encoding, the interleaved information bits to generate an interleaved codeword; and transmitting the interleaved codeword to the destination station.