Compressed Image Transmission Based On Fountain Codes

With the development of science and technology, especially wide application of the camera phones, high-definition television, video conference, remote sensing imaging and remote monitoring, multimedia communication has become more and more popular in people’s daily life. In the multimedia communication, image communication seems to be especially important since it is the main carrier of information. Thus, it attracts much attention in recent years.However, in the actual communication systems, the quality of image over channel transmission declines as noise interference. Therefore, the study of image compression transmission with the use of joint source-channel coding (JSCC) has very important theoretical and realistic significance.In this paper, we make use of rateless fountain codes as channel coding in order to protect the bit-stream generated by SPECK coding and ensure the accurate transmission on wireless channel. For two classes of fountain codes, LT codes and Raptor codes, we design different JSCC schemes and obtain perfect effect. At the same time, based on the traditional Equal Error Protection (EEP) scheme, an Unequal Error Protection (UEP) scheme is proposed. Specifically, the details are as follows:1. An EEP JSCC scheme based on the first class of fountain codes, LT codes are proposed.With the consideration of the characteristics of wavelet transform, the super SPECK algorithm is adopted for progressive transmission with low-complexity in source coding while LT codes are used to protect the bit-stream after SPECK algorithm in order to achieve high quality effect.2. An EEP JSCC scheme based on the second class of fountain codes. Raptor codes are proposed.In the scheme, Raptor codes are employed to protect the bit-stream after SPECK algorithm. Raptor codes consist of precoding and LT codes and can be considered as improved LT codes. Raptor codes inherit the rateless characters of LT and are superior in performance.3. An UEP JSCC scheme based on the second class of fountain codes, Raptor codes are proposedIn order to improve the error-correcting capability, the coefficients after wavelet transform are interlaced in the scheme. At the same time, combined with UEP technique, the bitstream can be protected in different classes for superior performance according the subband significance which are different from one to another.Finally, the paper makes a summary of the schemes on the above and gives some advice for improvement so as to provide a groundwork for future work.