Research on the baseband space-frequency modulation beamforming scheme

According to the complex number expression of smart antenna (SA) array element signals and the fundamental of QPSK modulation, a mathematic model of utilizing baseband QPSK modulated signal to realize SA directional transmitting beamforming is presented. With the mathematics model, the concept of baseband QPSK space-frequency modulation beamforming is proposed as well as the circuit structure unit of space-frequency modulator. Based on the circuit unit of space-frequency modulator, the key part of baseband QPSK space-frequency modulation beamforming equipment is derived, which is fit to the directional transmission of signals of multiple CDMA subscribers.