可分離之非均等錯誤保護LT編碼

Abstract

由於RS編碼複雜度與資料量呈平方倍的關係，相較之下LT碼擁有無比例碼的特性及線性編解碼複雜度，特別適合應用在無線網路的多重播送和廣播；此外，對於多媒體傳輸，由於資料擁有不同重要性，必須給予不同比例的保護，因此我們提出將LT碼結合非均等錯誤保護的功能，稱之為可分離之非均等錯誤保護LT編碼，根據不同資料所要求的錯誤保護率去調整編碼的連結關係，模擬結果顯示，我們所提出的方法只需改變編碼過程，且在不增加編解碼複雜度的情況下，達到比先前被提出的非均等錯誤保護LT編碼更好的結果。

With the properties of rateless codes and the complexity of encoding and decoding almost linear to input symbol number k, LT code is especially suitable for multicast and broadcast in cellular network since the complexity of RS code is quadratic to k. For multimedia application, data with different importance must be unequally protected which is named UEP (Unequal Error Protection). As a result, we propose a method that combines UEP and LT code called separable UEP-LT code. According to required error probabilities of data with different importance, we can adjust connections between codeword packets and input symbols. Simulation results show that comparing to traditional LT code, with packet loss rates of most important symbols 10-6 and less important symbols 10-2 lower than the UEP-LT code, we only have to change encoding process but keep the same decoding process as traditional one. Note that, no more complexities are increased in both encoder and decoder.