碼率相容之縮短低密度校驗碼與結合重覆編碼之混合式重傳技術

Abstract

在這篇論文裡，我們提出了一個針對低密度校驗碼的新的縮短碼長的方法，使得縮短碼之效能比原始碼更好，並透過前者所得之縮短碼的縮短位置，設計一套新的重覆編碼的混合式重傳技術。所提之縮短碼長的方法是透過維持連接性和減少短循環週期，使得整體的效能在高訊號雜訊比時能更好。我們提出的混合縮短碼長的重傳技術，能夠將錯誤碼字的錯誤更正能力較弱的地方，代換成一些和前次碼字錯誤更正能力較強的訊息並重傳，以模擬的結果和分析能得知所提的方法能夠讓一些出錯的碼字更正回來，提升整體的效能。

In this thesis, we study shortening and hybrid automatic retransmission request (HARQ) schemes for finite-length rate-compatible low-density parity-check codes. Shortening is a scheme to decrease the code length and the code rate by eliminating some information bits in a codeword. Instead of modifying the parity-check matrix, shortening LDPC codes can be performed by assigning infinite reliability on the associated variable nodes. We propose a new method to obtain shortening patterns which lead to better performance than the ones provided by the existing shortening methods. An HARQ scheme is an error control protocol based on combining forward error correction and error detection with retransmission requests. LDPC codes have been employed in HARQ protocols. We propose another novel LDPC code-based HARQ scheme in which the re-encoded information bits will be used as known information. Numerical and experimental results show that the proposed HARQ scheme provides a high throughput.