The Key Technologies Of Deep Space Communications

The main work and achievements of the author on image coding and transmission in recent years are systematically introduced in this dissertation. I focus on theory analysis and arithmetic investigation for image compression, namely embedded wavelet coding. Meanwhile deep space backbone network transport protocols are researched.An algorithm based on rate-distortion slope lifting for ROI (Region of Interest) coding is proposed, which overcomes the shortages of the bit plane lifting ROI coding method and keeps the compatible ability for the JPEG2000 standard. The new method enables flexible adjustment of compression fidelity in the ROI and background, and makes better qualities of the whole image. Aiming of the protection of the spectrum information in the satellite LASIS image, a self-adaptive rate-distortion slope lifting ROI method is proposed. This method mixes wavelet domain coding and error image coding are mixed, and then their code-streams are optimized so that better compression efficiency is obtained and the error propagation decreased. The offset between two adjacent images is the specificity of LASIS hyper-spectral images, which can be worked out by matching in wavelet domain in our new serial difference image compression coding method. It is easy for hardware implementation with low cost in storage and coding delay. Based on the analyses of multispectral images, a new compression algorithm is proposed based on the Partial 3D-SPIHT. To reduce the redundancies in the spatial and spectral domain and decrease the reconstructed spectrum error, we first use a 3D-DWT which combines two wavelet bases in the spectral domain. It relys on the probability of the significant coefficients in each bit plane to select one of three different coding modes, which enhance the coding efficiency.The reliable data transmission has become a key problem for the deep space communication because of the extremely high propagation delays, high link error rates, asymmetrical channel bandwidth and intermittent connectivity. The challenges and solutions for the deep space transport protocol are discussed with the comparison among different solutions described in detail. In order to reduce the effect of bandwidth asymmetry on the throughput performance, a modify TP-Planet protocol is addressed by the adoption of delayed SNACK.