使用低密度奇偶校驗碼之混合型自動重傳機制設計

Abstract

Hybrid automatic repeat request (H-ARQ) scheme is an adaptive rate error control system that can adapt to changing channel condition in wireless communication systems. Hybrid ARQ system can achieve desired throughput efficiency and reliability for the data packet network that requires error free data transmission and is insensitive to transmission delay. The performance of hybrid ARQ depends on the error correcting capability of error correcting code and its retransmission mechanism. Low-density parity-check (LDPC) code is chosen as our error correcting code for its strong error correcting capability. This paper focuses on designing an intelligent retransmission mechanism. We proposed a retransmission mechanism called type-II hybrid data puncturing (DP) and diversity combining (DC) ARQ scheme. In high signal to noise ratio (SNR) situation, data puncturing is applied to enhance the system throughput. In low SNR situation, diversity combining is used to facilitate robust transmission. Our scheme combines the strength of both schemes. In comparison to rate-compatible (RC) type-II hybrid ARQ scheme, the proposed ARQ scheme operates on much higher code rate LDPC code for encoding and decoding. It has lower encoder and decoder complexity than rate-compatible (RC) type-II hybrid ARQ scheme. Because of its low hardware complexity and throughput performance, the proposed scheme is suitable for the modern high throughput mobile communication system.