Paired Carrier Multiple Access System Interference Signal Delay Estimation Algorithm

Since the emission of the first artificial satellite by Soviet Russia in 1957, satellite communication technology has taken quite great development. In recent years, with the increasingly demand of the broad band and multimedia communication, various powerful tools have been emerging in endlessly to increase the capacity of satellite channel and PCMA(Paired Carrier Multiple Access) is just one of them. PCMA is a fundamentally new technique for two-way satellite and a novel method for frequency re-use which allows two different earth stations to use the same frequency, time slots and/or CDMA code at the same time. So properly applied, PCMA can effectively double the throughput of satellite systems and enhance the information security. There is seldom research on such technique inside and outside and only one patent literature discussed about it. The most difficult and important part of PCMA is the suppression of local downlink disturbing signal. After the system model being set up, interference suppression is discussed and the delay estimation algorithm is studied in detail. The results of the experiments show the method work well.The main contributions of this dissertation include:Introduce the basic concept and class of PCMA and then set up the base band transmission model. Discuss the interference subtraction process and signal suppression technique. The estimation of several key parameters is analyzed.The capture method of interference delay is studied and simulated. The method is based on the theory of statistic random signal and adopts the serial manner. The acquisition judge is performed by automatic threshold control.The tracking method of interference delay is studied and simulated. Referring to late-early loop gate, a method that applies to this system is proposed. Slight adjustment of delay difference is done by interpolation, so the whole digital structure is obtained.FPGA implement structure of the delay estimation is put forward and the way of realizing each sub-model is discussed in detail. The Verilog HDL coding and simulation are performed and the results show that the capturing and tracking method is accurate and feasible.