The performance of digital mobile radio communication systems is effected by signal fading and interference from co-channel users. Both these effects can be reduced by the use of antenna arrays at the base station with the appropriate signal processing and combining of the received signals.
In this thesis, a blind adaptive array beamformer against co-channel interferences is proposed. The beamformer's weight vector is calculated from auto correlation matrix of the received signals and cross-correlation matrix between the received signal vector and the signal vector shifted to the cyclic frequency of the desired signal vector. The proposed method utilizes the cyclostationary properties of the communication signal and has the constraints that maximize output SINR(Signal-to-Interference plus Noise Ratio). Also, this thesis is applied to the adaptive method with power method and recursive equations. The computer simulations to compare the performances between the proposed method and the conventional methods are performed. In the beam pattern, the proposed method has lower power gain than conventional algorithm at the interference directions. In the BER(Bit Error Rate) curve, the performance of the proposed scheme is superior than that of conventional schemes. Also, the adaptive beamformer algorithm is implemented in TMS320C31 DSP chip produced by Texas Instruments.