在錯誤效能具理想通帶濾波特性的通訊系統

Abstract

在此篇論文中，我們利用多層串接碼設計一個具有特殊效能表現的通訊系統，其錯誤效能接近理想低通或帶通濾波器的頻率響應。當系統的錯誤率小於特定的關鍵值時，我們能正確得到所傳送的訊息，反之當系統錯誤率大於該關鍵值時，我們即得不到所傳送的訊息。這種特殊的效能表現可應用在對於相鄰區域需有相反的傳送結果之特殊系統中。在我們所提出的多層串接碼設計的每一層中，每一個字碼會先延展成適合的字碼長度才被編碼。而在接收端，我們利用逐層解碼的方式，以得到相似於理想低通濾波器頻率響應的效能表現。接著，藉由變更上述系統的架構，可得到相似於理想帶通濾波器頻率響應的效能表現。然而，由此種多層串接碼所得到字碼數量過於龐大，所以我們提出另一種多層串接碼的設計來解決這個問題。這個新的多層串接碼能有效地縮小字碼數量，並且能得到所要的效能表現，使得利用它所設計的通訊系統更具實用性。

In this work, we propose the multistage concatenated (MC) coding scheme to design a communication system whose error performance approaches the ideal low-pass filtering (LPF) or band-pass filtering (BPF) characteristic. Only when lies in the acceptable region, it is guaranteed to correctly retrieve the transmitted message. Otherwise, it is almost impossible to recover the message. This special result could be useful for some applications where sharp distinction between two nearby regions or power levels is required. The MC coding scheme is composed of several stages, whereas each stage consists of the word-extension process and the error-coding process. Due to the multistage concatenated decoding, the ideal LPF error performance can be achieved. Further, the BPF error performance can be obtained by modifying the system configuration. However, the codeword size resulted from the MC coding is too large for some applications; so a modified MC coding scheme is designed to solve this problem. This new MC coding scheme can successfully reduce the codeword size and still achieve the LPF error performance, so that the proposed communication system is feasible for practical applications.