Application of multipath combiner and equalizer in a multi-channel direct sequence spread spectrum communication system

摘要

A receiver subsystem in a multi-channel direct sequence spread spectrum system consists of a signal register, a multipath detector, a multipath combiner, a decision-feedback equalizer, a multi-channel detector, and a multi-channel signal regenerator. First, the multipath detector finds out the information about various components of a multipath-fading signal. Then the multipath combiner combines the significant components from corresponding tapped outputs of the signal register together. Next the decision-feedback equalizer eliminates interference from the output signal of the multipath combiner. After receiving signal from the decision-feedback equalizer, a multi-channel detection circuit recovers the information and estimates the complex signal for each channel. The multi-channel signal regenerator resorts to these complex signals to generate the estimated transmission signal. It multiplies each estimated complex signal by a corresponding spreading signal, summarize all the products together, and then multiply the summation by a scrambled signal. Finally, the regenerated multi-channel signal and the delayed version of the output signal of the decision feedback equalizer are compared to produce error signal for updating the coefficients of the decision feedback equalizer.