Research Of Joint Source-Channel Coding Of Image In Wireless Channel

With the developing rapidly of the mobile communication fields today, people pay more and more attention on the transmission of multimedia data in wireless channel, including speech, images and video and so on. All of the characteristics of wireless channel, such as time-varying, attenuation, large interference and limited bandwidth resources and so on, requires that we must find a coding way to together information source and channel. However, there are two issues that must be considered to find this joint coding method, which are the problem of source coding and channel coding. The purpose of source coding is to reduce signal redundancy as much as possible, that can increase the effectiveness of the system. By contrast, the purpose of channel coding is to add redundancy in the information sequence properly. Thus, the reliability of system will be increased by correct-ing errors in the transport process. In a sense, they are contradictory. As a result, the emphasis of designing joint source-channel coding is on how to weigh the source coding and channel coding.Limitations of Shannon’s theorem provides theory basis for joint source-channel coding/decoding. In this paper, we mainly research the joint source-channel coding technology that based on unequal error protection. This plan fusions bit rate allocation technology of joint source-channel coding and unequal error protection (UEP) technology, so as to benefit system performance. There are two steps during the encoding transmission system. Firstly, it distributes reasonably coding bit rate of the two encoders (source coder and channel encoder) according to the current channel conditions. Then, the improved SPIHT source encoder and RCPT channel encoder have be together to complete the designing of the whole scheme. And the performance and the transmission reliability of the system are improved under the condition of without increasing the bandwidth. Secondly, this paper analyzes the performance of SPIHT algorithm, and improves according to its advantages and disadvantages. It achieves performance optimization of SPIHT algorithm through its virtual tree structure. Besides, the unequal error protection of source code data is achieved through rate compatible Turbo code (RCPT), and is conducted experimental simulation. Through the simulation results, we can see that the joint source-channel coding enhances the antinoise performance of image coding.