Digital beam-forming implementation for downlink smart antenna system

In this paper, we present a new structure to implement a switch-beam smart antenna system. The system is able to produce the beam with 6-degree beam-width and steer the beam from 0 to180 degrees in azimuth angle. The proposed system takes the advantage of integrated digital signal processing (DSP) and field programmable gate array (FPGA). In the system, the TI DSP performs digital beamforming and sidelobe cancellation algorithms, while the APEX FPGA performs channel separation and synchronization tasks. The system is aimed to operate with sixteen elements in the array. Therefore, sixteen complex weights are produced according to user's location. The user signal after phase adjustment is further manipulated by Dolph-Chebyshev's coefficients to achieve the desired main-lobe to side-lobe ratio. After performing the side-lobe cancellation and beamforming by DSP, the FPGA splits the DSP's output to sixteen channels linked to 16 microstrip antennas. The results drawn in Matlab indicate that there is 100% agreement between simulation results and hardware outputs.