Leo Satellite Cdma Transmission System Principles And To Achieve

The land-mobile-telecommunication gets a rapid progress in.recent years, the popularization rate of cell mobile telephone, wireless telephone, Beep-Pager and the relative technology is very high in the developed country, but it can only covers the city area, its distance is limited. The satellite-telecommunication has a serial of characteristic such as long distance, large coverage area, wide communication band, big transmission capacity, high quality, it has made a rapid progress in the last decades and become one of the most powerful communication methods today.The advantages of using LEO satellite are as following: on the one hand the satellite orbit is low, so the transmission delay is short, the power loss is small; on the other hand the development of cell communication, multi-access, frequency multiplex and etc also provide a technique guarantee to the LEO satellite-mobile-telecommunication. So the LEO system is considered to be a satellite-mobile-communication system with a great future. In this text we will discuss the principle and implementation of a LEO satellite CDMA transmission system.Chapter 1 introduces satellite-telecommunication, satellite-mobile-telecommunication and its multi-access methods, studies the general situation of CDMA. Gives a brief introduction to the LEO satellite CDMA transmission system.Chapter 2 studies the principle of the LEO satellite CDMA transmission system. Introduces multi-user access, slot alignment and power control, contention resolution. Presents the multi-user access method based on CDMA employed in the backward link. Then we give a brief compare to the m-serial, Gold-serial and Walsh-serial.Chapter 3 presents the implementation of the LEO satellite transmission system. The transmitter does the work of a burst transmission, its encoding and framing are all implemented in the link control part, the base-band process part does the spreading, FIR filtering and up frequency conversion. The main work of the base-band process part of the receiver is demodulation and decoding, the link control part does the framing and forwarding.Chapter 4 discusses the principle and implementation of Viterbi decoding. We began with algorithm and parameter analyze; then come to the architecture of the decoding and the function of each module; at the end is the implementation of decoding in the FPGA.