Phased-COSTAS coding of MIMO radar waveforms for transmit beamforming using generalized ambiguity functions

Çelik, Ozan Onur
Multiple-input multiple-output (MIMO) radars have attracted interest due to some important advantages over Phased-array radars. The diversity that comes with multiple waveforms is used to maximize the power in the vicinity of targets and minimize the cross correlation of waveforms reflected from multiple targets for a predefined angular sectors. In this study, a novel approach is presented to overcome the limitations of current beamformer design techniques in terms of bandwidth, auto/cross (spatial) correlations, range-doppler resolutions, peak-to-average ratio (PAR), and mean squared error (MSE) for desired beamforming pattern. A generalized ambiguity function formulation is presented which employs all the beamformer design parameters in a mathematically tractable simple manner suitable for constrained optimization. We present Phased-Costas coded waveforms to generate desired beampatterns while minimizing range-doppler sidelobes and target cross-correlations with limited bandwidth. Beamformer design problem is casted as a constrained optimization which includes PAR constraints. The resulting NP hard problem with nonconvex objective function is converted to a convex problem and efficiently solved by using ADMM technique in polynomial time. The optimum beamformer solution is shown to achieve PAR=1 with very little degradation compared to the unconstrained problem making the ultimate choice for MIMO beamforming applications. Several good features of the designed beamformer are shown through simulations and compared to known methods.


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Citation Formats
O. O. Çelik, “Phased-COSTAS coding of MIMO radar waveforms for transmit beamforming using generalized ambiguity functions,” M.S. - Master of Science, Middle East Technical University, 2021.