Collocated MIMO radar waveform coding using Costas and Quadratic Congruence arrays

Multiple-input-multiple-output (MIMO) radar with collocated antennas transmits orthogonal waveforms to allow the received echoes to be used efficiently for range and Doppler estimation. The orthogonality of the transmitted waveforms should hold for both time shifts and frequency shifts. This paper, for the first time, extends two time-frequency hopping coding methods - the Costas Array Coding (CAC) and the Quadratic Congruence Coding (QCC), which were commonly used in single-input-single-output (SISO) radar and sonar applications, to MIMO scenario, and formulate the novel optimization problems. By decomposing the MIMO ambiguity function (AF), we analyze their auto-ambiguity functions (AAF) and cross-ambiguity functions (CAF). Linear frequency modulation (LFM) signal is used for the coding. Simulation shows that MIMO radar is superior to conventional single-input-single-output (SISO) radar in terms of sidelobe reduction, and the delay resolution can be significantly improved by increasing the coding dimension.