基於混合式擷取技術之碼率相容穿孔迴旋碼

Abstract

擷取技術是一種藉由週期性的刪除編碼器所產生的輸出，來達到提供迴旋碼更彈性的碼率選擇。傳統的擷取技術可以分成兩大類：正規擷取或非正規擷取。當編碼器的每一個輸出都對應到同樣的擷取周期時，吾人將其稱為正規擷取技術。相反的，非正規擷取技術允許編碼器的每一個輸出都能對應到不同的擷取週期。這兩種擷取技術都可以達到增加碼率選擇多樣性的目的。甚至於藉由使用非正規擷取技術，還可獲得某些在正規擷取技術下所無法產生的碼率。經由加入碼率相容規則，這些擷取技術可以用來產生碼率相容穿孔迴旋碼。在本篇論文中，吾人發現可以經由混合正規及非正規擷取技術來組成新一種類的碼率相容穿孔迴旋碼，此種碼率相容穿孔迴旋碼可以更進一步提供更多碼率的選擇性。此外，相對於傳統的碼率相容穿孔迴旋碼，此類碼率相容穿孔迴旋碼也可提升錯誤更正能力。相關的分析討論以及模擬結果也都會呈現在本論文中。最後，經由電腦搜尋所彙整的新種類碼率相容穿孔迴旋碼結果，也將一併呈現。

Puncturing is a useful technique to provide more flexible code rates for convolutional codes by deleting some outputs of the encoder periodically. Conventional puncturing techniques can be divided into two scenarios: the regular or the irregular puncturing. When each output of the encoder has the same puncturing period, it is called the regular puncturing technique. In contrast, the irregular puncturing technique allows that each output of the encoder can have different puncturing periods. These two puncturing techniques both can increase the variety of code rates. Moreover, some code rates which cannot obtained with regular puncturing technique can be achieved by applying irregular puncturing technique. Both of these puncturing techniques can be modified for the generation of a family of codes by adding a rate-compatible rule and these codes are named as rate-compatible punctured convolutional (RCPC) codes. In this thesis, we show that the regular and the irregular puncturing technique can be used together to construct a new subclass of RCPC codes which can further offer more choices of code rates and error-correcting capabilities can also be improved compared with the conventional RCPC codes. Both of the analytical discussion and simulation results are also provided. Finally, tables of new RCPC codes are also presented by computer search.