Robust transmission of html files : Iterative joint source-channel decoding of Lempel Ziv-77 codes

This paper concerns the error correction of corrupted compressed HTML pages during their transmission via a noisy mobile channel. The proposed receiver is based on an iterative joint source channel decoding approach similar to the turbo decoding of two serial concatenated codes. We propose a soft-input soft-output Lempel-Ziv inner decoder based on the modified version of the traditional sequential decoding M-algorithm. This new algorithm exploits the specific grammatical rules of the Lempel-Ziv-77 codes which are combined to the syntax of the HTML language. This source decoder is combined to a Soft-Input Soft-Output channel decoder of convolutional codes. Simulation results, over an additive white Gaussian noise channel, show that the proposed method drastically reduces the number of files in error compared to any conventional channel decoding.