Distributed multiple-input–multiple-output radar waveform and mismatched filter design with expanded mainlobe

Distributed multiple-input–multiple-output radar usually needs to transmit nearly orthogonal waveforms, but the constant-modulus requirement from engineering applications often makes sidelobe levels difficult to suppress. In this study, the authors resort to two approaches to further suppress the sidelobe levels, i.e. orthogonal phase-coded waveforms with expanded mainlobe (OPCWEM) and its mismatched filters design. Specifically, they first propose a minimisation criterion to design nearly OPCWEM, which is a non-convex optimisation problem and solved by a least-pth minimax algorithm. Next, they design mismatched filters with given OPCWEM, which is formulated as a convex optimisation problem with min–max criterion and solved by a convex optimisation algorithm. Numerical results validate the effectiveness of the two approaches and the Doppler sensitivity is also analysed.