针对信源与信道编码各自的特点,提出了一种基于SPECK（set partitioned embedded block coder）算法和Turbo码相结合的信源信道联合编码方案.由于图像经SPECK算法编码后的数据流对信道噪声非常敏感,所以可采用此方案来提高图像对信道错误的鲁棒性.该方案通过SPECK算法来产生具有不同容错性的子流,信道编码采用删余Turbo码,用不同码率的信道编码来对这些子流进行非平等保护,以改善数据流抗信道差错的整体性能.这种方案充分利用了信源编码后的数据流的特性,从而使误码率与码长达到了一个较好的平衡.实验结果表明,该方案不仅能够在较高的压缩比下,使解码图像具有较高的峰值信噪比,并且由于Turbo码的优异性能,使得图像在较低信噪比条件下进行传输仍具有较强的鲁棒性.

This paper presents a joint source-channel coding scheme based on SPECK and revises turbo codes according to the characteristic of source and channel coding.The purpose of this scheme is to improve the robustness of the image.Source coding in this paper adopts image coding based on wavelet.This scheme uses SPECK to generate diverse fault tolerant substream.Punctured Turbo codes are used for channel coding.Channel coding adopts unequal error protection(UEP) for the compressed data with different channel coding rates according to the importance for reconstruction.This scheme utilizes the property of compressed data which source has coded and gets better balance between bit error rate and code length.The experimental results show that the proposed scheme can get high PSNR(peak signal noise ratio) in high compression ratio and provide strong robustness to the image in low SNR because of the superior performance of Turbo-codes.