A Study of Reliability Based Hybrid ARQ Scheme with Bitwise Posterior Probability Evaluation from Message Passing Algorithm
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Reliability Based Hybrid ARQ (RBH-ARQ) is one of hybrid ARQ schemes with the modified decision feedback. In RBH-ARQ, the modified feedback is composed of both ACK/NAK signal and unreliable bit index which is evaluated from bitwise posterior probability. In the conventional RB-ARQ, the sender retransmits just unreliable information bits with no coding when unreliable bits are detected on the receiver and retransmission occurs. In the proposed RBH-ARQ, on the other hand, the sender retransmits not information bits but newly encoded parity bits corresponding to the unreliable information bits assuming systematic convolutional coding. Furthermore, the proposed scheme assumes message passing algorithm for Maximum A Posteriori probability (MAP) decoding on the receiver. The receiver puts received bits including retransmitted parity bits all together into our proposing probability model. As a result, better performance can be expected in the proposed RBH-ARQ since our probability model is similar to the celebrated decoding model of multiple Turbo codes. Finally, brief simulation results based on several message passing schedules in our algorithm would be shown.
- IEICE technical report. Information theory
IEICE technical report. Information theory 105(85), 11-16, 2005-05-20
The Institute of Electronics, Information and Communication Engineers