DFT-Spread OFDM MIMO-Radar – An Alternative for Reduced Crest Factors

Multiple-input multiple-output radar has been recognized as an interesting option for near- to medium-range radar applications, since its virtual antenna array concept offers increased angular resolutions at a compact installation size. Orthogonal frequency-division multiplexing (OFDM) - which is widely employed in wireless communications - has been shown to provide an efficient means to establish the required orthogonal transmit signals. Despite its many advantages, a well-known drawback of OFDM is that transmit signals are typically characterized by relatively high crest factors. This requires corresponding power back-offs at the transmitter side or power amplifiers with highly linear characteristics, so as to avoid undesired signal distortions. In this paper, we propose an alternative OFDM-based waveform adopted from wireless communication systems, which employs a pre-spreading stage by means of a discrete Fourier transform (DFT). By means of computer simulation results, we show that DFT-spread OFDM has similar radar properties as OFDM, while crest factors can be reduced considerably. This renders DFT-spread OFDM a particularly “hardware-friendly” modulation scheme.