Study On Joint Source Channel Coding For Wireless Image Transmission

The transmission of images over wireless communication channels is still a challenge problem. Digital compressed images are sensitive to bit errors which are typical in wireless communications. Moreover, the bandwidth at the air interface is currently a limiting factor because the first and second generations of mobile phone standards mainly support voice communications. In this thesis, different integrating schemes of joint source-channel coding and decoding for error resilient image transmission over wirelesss channels are examined. In order to comparing the performance of joint coding system proposed in the thesis between the actual simulation and theory limit, we study the error exponent of joint source channel coding, and use the results to analyze the proposed joint source channel coding system. The detailed content is listed in the following.In the second chapter, a joint source channel coding algorithm based on error correcting arithmetic codes is proposed, in this algorithm, the arithmetic coding with the forbidden symbol is used to coding via one step, the probability of the forbidden symbol is adjusted adaptively according to the channel state information (CSI). Unlike the conventional channel adaptive joint coding algorithm, only one parameter needs to adjust in our algorithm. Furthermore, a continuous coding rate could be achieved theoretically. MAP decoding metrics are developed. In addition, a improved sequential search algorithm using stack is proposed. The proposed algotithm is tested in the case of image transmission, and excellent results in terms of packet error rate and decoded image quality are obtained.Secondly, a new joint distortion model for transmission progressive image on the memoryless channel is proposed in chapter 3. In our model, the distortions generated by quantization and the channel errors are considered jointly, and the distortion of every layers is computed separately. The new characteristics lie in. First, the arithmetic codes with the forbidden symbol are used as source channel coders, and the redundancy coming from the forbidden symbol is use to distinguish...