SYNCHRONOUS DUPLEX CHANNEL QPSK MODEM IN CDMA SYSTEM AND MODULATION AND DEMODULATION METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To eliminate crosstalk interference, to minimize channel parameter estimation errors and to improve reception performance by using Walsh codes in mutually orthogonal relation and making an I-arm and a Q-arm orthogonal with each other. ;SOLUTION: Pilot signals, I-input data and Q-input data are respectively inputted to a pilot channel 111, the I-arm 112 and the Q-arm 113 and the pilot signals are amplified 10. The two Walsh codes orthogonal with each other are respectively multiplied with I-input signals and Q-input signals in multipliers 13a and 13b and spread. The amplified 10 pilot signals are added 14 with the spread I input signals, pseudo-modulated by the multiplier 15a and spread to a PN code. Also, the spread Q-input signals are spread by the multiplier 15b. The spread I-signals and Q-signals are turned to pulses by forming filters 11a and 11b, amplitude-modulated 17a and 17b to a cosine and a sine, added 16 and transmitted through an antenna 12.;COPYRIGHT: (C)1997,JPO