Synchronization and Detection of Binary Data in Free-Space Optical Communication Systems using Haar Wavelet Transformation

摘要

A new method is presented to perform bit synchronization and detection of binary nonreturn-to-zero (NRZ) data from a free-space optical (FSO) communication link. Based on the wavelet transformation, a new bandpass filter is developed and implemented. It is shown that the Haar wavelet is an excellent choice for this purpose. The center frequency of this filter is a function of the scale and could be adjusted to adapt to the variation of the channel. The output of the filter is zero mean and is closely related to the derivative of the binary data. The filter has a linear phase; therefore, its output is used for synchronization and detection of the data. Analysis of the method is presented using Fourier transformation. In addition, adaptive Wiener filtering is utilized to reduce the effect of the additive white Gaussian noise in the data. Simulation experiments are performed and presented using real and synthetic data. The results of the experiments indicate that the Haar wavelet transform and adaptive Wiener filtering are robust and effective tools in dealing with FSO data.