Error-resilient Coding Algorithm For Images Of Deep Space Communications

Deep space exploration, one of the three space activities of the21st century,has great scientific value and economic significance, which means a country’s levelof technological development and comprehensive national strength. As a part of thedeep space exploration, deep space communications play an essential role in thescientific data transmission. Image information is the most visua lized performanceto space exploration as a main form of all kinds of data to transmit. Therefore, it isvery important to ensure the reliable transmission of image. But deep spacecommunications face long distance which leads to a direct result of the large signalpower fading, huge propagation delay, and communication link interrupts causedby the movement of celestial objects. In order to ensure the reliable communicationin this scenario, the urgent demands on how to design an image coding and channelerror correction coding is proposed. Thus, it is necessary to study the image codingusing fountain codes with unequal error protection. In this paper, we show theimage layering and channel coding for ensuring the reliable transmission ofimportant parts of the image data. We solve this problem by the following twoaspects:Firstly, the research of wavelet transform and image layering are shown in thispaper. Deep space has rich and extremely valuable image information, but theredundancy of image data is larger so as to reduce the efficiency. Thus, directtransmission is not suitable. At the same time, Deep space communication is easyto be interrupted, which request to ensure the relia ble transmission of importantdata in transmission process. Thus, it is the first problem how to distinguish theimportant data from all the information. The wavelet transform has thecharacteristics of multi-resolution analysis, which can take the main energy of thesigna l be concentrated in low frequency data. Thus, we use the wavelet transformfrom CCSDS image compression algorithm to process the images. The wavelettransform not only has low computational complexity, but also has a good way tostratify for image. In brief, the wavelet transform can accurately achieve thedivis ion for the important data.Secondly, we design a scheme of image coding using fountain code withunequal error protection (UEP). For the characteristics of deep space channel, inorder to improve the validity of the transmission image, we use channel coding toensure reliable transmission of important data on the reconstructed image, whichmeans we protect important data and assign a higher code rate for important data.Fountain codes applied to deep space channe l transmission, process data by the form of equal error protection. Thus, we study the unequal error protection codingbased on fountain codes. The simulation analysis shows optima l parameter ofunequal error protection algorithm by asymptotic performance analysis of And-Ortree technique. According to the combination of image wavelet transform andfountain codes with UEP, we have designed an integrated image coding schemeusing UEP error-resilient coding, and verified the feasibility of the scheme in thedeep space.