Orthogonal Waveform Design For MIMO Radars

Multiple-input multiple-output (MIMO) radar is a new radar system,whose multiple transmitting antennas transmit orthogonal signals and multiple receiving antennas receive returns. MIMO radar can effectively improve the performance of interception resistance, the ability to detect low-speed target on the background of clutter, and the detection ability of weak targets on the background of strong clutter, etc. MIMO radar transmit orthogonal signals for avoiding mutual interference between channels and acquiring larger spatial diversity gain. This means that the transmitting signals should have smaller cross-correlation values. Meanwhile, MIMO radar request signal autocorrelation should have lower side-lobe to maintain high range resolution.The design of low autocorrelation side-lobe and cross-correlation is one of the key techniques of MIMO radar systems. Firstly, the orthogonal linear frequency modulation signals are designed. The cost function is then chosen as the square of autocorrelation peak side-lobe, the square of cross-correlation peak, autocorrelation and cross-correlation energy. A novel hybrid algorithm, combined genetic algorithm and greedy algorithm optimization, is proposed to search orthogonal polyphase code and applied to design 4 phases and 32 phases for orthogonal polyphase code. After that, 32 phases of orthogonal ployphase is designed by relaxing the main-lobe width of its autocorrelation. Next, the design of random phases orthogonal polyphase code is presented. Simulation results show that all designs are effective and feasible. Finally, Simulation results show that white noise and chaos signals can be used as the signals of MIMO radar.