Low-Complexity Soft Decoding of Huffman Codes and Iterative Joint Source Channel Decoding

Abstract

International audienceMost source coding standards (voice, audio, image and video) use Variable-Length Codes (VLCs) for compression. However, the VLC decoder is very sensitive to transmission errors in the compressed bit-stream. Previous contributions, using a trellis description of the VLC codewords to perform soft decoding, have been proposed. Significant improvements are achieved bythis approach when compared with prefix decoding. Nevertheless,for realistic VLCs, the complexity of the trellis technique becomesintractable. In this paper, we propose a soft-input VLC decodingmethod using an a priori knowledge of the lengths of the sourcesymbolsequence and the compressed bit-stream with Maximum A Posteriori (MAP) sequence estimation. Performance in the case of transmission over an Additive White Gaussian Noise (AWGN)channel is evaluated. Simulation results show that the proposed decoding algorithm leads to significant performance gain incomparison with the prefix VLC decoding besides exhibiting very low complexity. A new VLC decoding method generating additional information regarding the reliability of the bits of the compressed bit-stream is also proposed. We consider the serial concatenation of a VLC with two types of channel code and perform iterative decoding. Results show that, when concatenated with a recursive systematic convolutional code (RSCC), iterativedecoding provides remarkable error correction performance.In fact, a gain of about 2.3 dB is achieved, in the case of transmission over an AWGN channel, with respect to tandem decoding. Second, we consider a concatenation with a low-density parity-check (LDPC) code and it is shown that iterative joint source/channel decoding outperforms tandem decoding and an additional coding gain of 0.25 dB is achieved

Performance Improvement of JSCC Scheme Through Redesigning Channel Code

“…The redundancy left by source encoder is exploited by channel decoder to reduce the bit error rate (BER) through joint belief propagation (BP) algorithm. This is the same as other JSCC schemes [2], [3].…”

Generalized Joint Shuffled Scheduling Decoding Algorithm for the JSCC System Based on Protograph-LDPC Codes

“…Therefore, the joint source-channel coding (JSCC) system has drawn increasing attention through effective utilization of the residual redundancy. The JSCC system have good error-correcting performance [2], complexity [3], [4] and transmission delay [5], and these advantages promote the JSCC system for applications in image processing [6], video transmissions [7] and so on. The JSCC system, where one low-density parity-check (LDPC) code [8] is used for source compression and one LDPC code is used for channel error correction, was proved to perform well in practical applications by utilizing the joint Tanner graph on the decoder side, named the double LDPC (D-LDPC) JSCC system [2].…”

Joint Source-Channel Decoding of Polar Codes for Language-Based Sources

“…Joint decoding of Huffman codes and Turbo codes is proposed in [4]. A low-complexity chase-like decoding of VLCs is given in [5]. However, few works have been done for JSCD specifically for language-based source.…”