Research And Verification Of Synthetic Technology Of Circular Array Digital Array

Smart antenna technique is introduced into mobile communication since 1990s, whose main purpose is to realize SDMA and user positioning. This technique has been widely applied recently because of its attractive characteristics such as flexiblility of beam-pattern control, ability of anti-jamming and increment of system capacity.Firstly, beam-pattern optimization algorithm is researched for wide acquisition beam and wide angle measurement beam synthesis. The research on low side-lobe tracking beam optimization technique is also conducted. A MMSE Beamforming Algorithm is proposed, and it is based on pattern approximation of main lobe and sidelobe weighting. Then the GUI based "Circular Digital Array Antenna Pattern Optimization Software" is developed, which is integrated the beam-pattern optimization functions for simultaneous multi-user acquisition, angle measurement and tracking beam requirements. The test results of microwave anechoic chamber show that the 3 dB-width of the optimized acquisition beam is broadened over 10 degrees, and the side-lobe of the optimized tracking beam is suppressed more than 2.5dB under the condition of same main-lobe gain. The optimized test results satisfy the system index requirements.Secondly, based on the actual characteristics of spread spectrum communication system, a specialized test simulator is developed. And the purpose is to verify the function and performance of "Digital Multi-Beam and Angle Estimation Circuit FPGA Program" in which the above techniques are applied. This simulator uses a structure that combined PC software and FPGA circuit. It can simulate 9-channel baseband spread spectrum signal with different SNR, Doppler frequency, Doppler acceleration and user angle. Furthermore, it can be used to verify the influence that Doppler frequency estimation error and symbol synchronization error have on "Digital Multi-Beam and Angle Estimation Circuit FPGA Program". Lastly, the validity of the specialized test simulator’s functions is verified by system tests, which effectively improves the development and performance testing efficiency of "Digital Multi-Beam and Angle Estimation Circuit FPGA Program".