Research On QOTDM Technology For The Downlink Of FDMA-CWTDM System

FDMA-CWTDM satellite communication system has the features of simple equipment on board, high flexibility in application. The QOTDM (Quasi-Orthogonal Time Division Multiplexing) technology can be used to solve the problem of reliably transmitting multiple continuous signals in a continuous channel, and the original signals can be recovered without distortion in the receivers. This technology has the advantages of high frequency efficiency, high flexibility in implementation, low equipment complexity at the transmitting terminals and equalizing the channel easily.Based on the research of QOTDM technology and FDMA-CWTDM satellite communication system, the application of QOTDM technology in the downlink of FDMA-CWTDM system is mainly discussed in this thesis. The author's main contributions are as follows:1. Based on research of the principle and key techniques of the CWTDM and QOTDM, a scheme is proposed, which includes the transmitting and receiving terminals of downlink.2. The generating method of special pilot sequence is researched. The techniques for the receivers are researched, which include carrier synchronization, high precise frame synchronization and channel equalization. And a simplified scheme of receivers is proposed via combining synchronization loop with adaptive equalizer. As a result, the complexity of receiver is reduced greatly.3. The transmitting terminal of the downlink of CWTDM system is implemented with FPGA, which is verified via post-synthesis timing analysis.