Analysis Of The Performance In Intersatellite Optical Communication Systems With Wavefront Deformation

With the development of human activities in space field, intersatellite optical communication technology has shown the potential application in science, military and commercial communication, etc., and have aroused widespread attention. The advantages over traditional RF and microwave communication make it an ideal option in intersatellite communication systems, which can be concluded as smaller and lighter terminals, less transmitter power, larger bandwidth, stronger anti-interference ability, greater security and so on. Due to the ultra-long communication distance and the beam divergence angle in micro arc, high beam quality is required to ensure well system performance. However, affected by the complex outer space environment and the precision error during machining and alignment, wavefront deformation appears and degrades laser beam quality, even system performance. Moreover, the limitation of optical antenna size and transmitter power also make it harder to improve system performance.Considering these aforementioned problems above, the wavelet method is applied to build the theoretical model of diversified wavefront deformation. And system performance of different modulation schemes is compared in the presence of wavefront deformation. The main work is as follows:Firstly, for the reflection-style and transmission-style optical antennas, with wavelet method, diversified wavefront deformation can be described by wavelet parameters:coefficients, dilation and shift factors, where coefficient factor represents the depth, dilation factor represents the area and shift factor is for location. In order to analyze how optical intensity in receiving plane is impacted by wavefront deformation, it is given as a function of each wavelet parameter respectively based on beam propagation theory.Secondly, detector noise is often neglected in the study of system performance with wavefront deformation. Under this condition, OOK, DPIM and PPM modulation schemes are chosen and compared in intersatellite optical communication systems. And packet error rates (PER) of these modulation schemes related to wavefront deformation parameters:depth, area and location are derived for both reflection-style and transmission-style optical antennas. When wavefront deformation gets deeper, wider and closer to the center of antenna packet error rate is analyzed correspondingly. Furthermore, packet error rates of these modulation schemes in the deformed system are compared.Lastly, considering detector noise, the relationship between packet error rate and wavefront deformation parameters is re-established for reflection-style optical antenna. packet error rates of OOK, DPIM and PPM modulation schemes are also researched and compared.Wavelet method shows its advantages in computational complexity and varied wavelet basis in the study of wavefront deformation. Meanwhile, DPIM and PPM modulation schemes have better performance than OOK, in terms of power efficiency as well as packet error rate. The work in this dissertation will make sense for the design of intersatellite optical communication system.