Complex matched FIR filters for detection of primary and secondary synchronization codes in W-CDMA

This paper presents the design and FPGA implementation of complex matched filters for the detection of primary and secondary synchronization codes in W-CDMA communication systems. The primary complex matched filter is required for the detection of the unique primary synchronization code of 256 bits while the secondary matched filter is designed to detect any one of 16 secondary codes of 256 bits each. The design of the 256 tap primary complex matched filter is based on the differential method with view to exploiting the characteristics of the primary synchronization code and reducing the number of multipliers required in the implementation of the filter circuit. The 256 tap secondary complex matched filter consists of four identical sub-filters of which two process the real and two process the quadrature data streams. The designs have been implemented on Altera´s Apex II EP20K400EBC652-3 device. Simulations for throughput on both filters show a performance of 80 Msamples/s for the primary and 36 Msamples/s for the secondary complex matched filters respectively.