Virtual MIMO radar using OFDM-CDM waveforms

This paper addresses a new perspective on the exploitation of diversity resembling recent seminal proposals with multiple antennas known as MIMO radar. Our focus pursues similar advantages as spatial MIMO systems but intending to achieve the desired resistance over fading or/and SNR increase without relying on multiple antennas. We design an OFDM-CDM waveform well inspired in modern communications systems that creates a virtual MIMO system operating on the artificial 2D domain formed by a set of well separated carriers (OFDM) and several OFDM symbols each one modulated by orthogonal codes (CDM). We consider the most general scenario with moving targets and large size targets originating an equivalent time variant and frequency selective channel model. Our proposal proceeds in two steps, a first one to reorthogonalize the transmitted set of OFDM signal by proper time and frequency synchronization (this stage provides range and velocity estimators), and a second one based on Neyman Pearson detection improved by the diversity gain.