A modified acquisition method with code-orthogonalizing filters in asynchronous DS/CDMA

We present synchronous acquisition methods using code-orthogonalizing filters (COFs) in asynchronous direct sequence (DS)/CDMA. In the systems, the tap coefficients of the COF are controlled to orthogonalize to all users sequences including the desired user's spreading sequence. Several probable synchronous phases are selected by using the difference of correlation function value between the tap coefficients and the desired user's sequence for each phase. Then, the most probable synchronous phase is decided from these phases by a previous proposed precise acquisition system. By computer simulations, we show the improvements of the average acquisition time under several conditions.