MIMO OFDM chirp waveform design with spread spectrum modulation

This paper proposes an approach to design orthogonal multiplexing waveform for use of Multiple-input Multiple-output (MIMO) radar. The designed scheme incorporate direct sequence spread spectrum (DSSS) coding techniques on orthogonal frequency division multiplexing (OFDM) chirp signaling. We call it spread spectrum coded OFDM chirp (SSCOC) signaling. The performance of the signals are analyzed with the cross-ambiguity function. In the experiment, the influence of spread spectrum code length and type as well as the bandwidth and duration of OFDM chirp waveforms on cross-ambiguity function (CAF) is discussed. It is verified that the proposed design scheme can ensure these waveforms stay orthogonal on receive and obtain large time-bandwidth product which are beneficial to separate closely spaced targets with ultra-high resolution.