Cdma modulation and demodulation method reducing interference and a

Abstract

A CDMA (Code Division Multiple Access) modulation and demodulation method and a communication system using the same which simultaneously transmits a pilot signal and a data signal through the same channel, thereby being capable of not only greatly the complexity of its transceiver, but also achieving an improvement in performance where a large number of multipaths are used. The method includes the steps of (a) generating a pilot signal and a transmission data signal; (b) spreading the pilot signal and the transmission data signal, by multiplying the pilot signal by an inphase pseudo noise sequence and by multiplying the transmission data by a quadrature pseudo noise sequence, respectively; (c) generating an inphase signal and a quadrature signal, by multiplying the spread pilot signal by an inphase walsh data sequence and by multiplying the spread transmission data by a quadrature walsh data sequence, respectively; (d) modulating the inphase signal and the quadrature signal, by multiplying the inphase signal and the quadrature signal by carrier signals; and (e) transmitting a composite signal created by adding the modulated inphase signal to the modulated quadrature signal.