Impact of the Doppler modulation on the range and Doppler processing in OFDM radar

Abstract

Orthogonal frequency division multiplexing (OFDM) radar is highly appropriate in applications where communication and radar functionalities are intended simultaneously. The same waveform and the same infrastructure are used, reducing hardware complexity. In this paper, we focus on the radar processing of a pulsed waveform, where the pulses are composed of several OFDM symbols. We derive a novel signal processing scheme that retrieves an estimate of the range and the radial velocity when the target is a point scatterer. Rather than a processing based on correlation functions we exploit the phases of the subcarriers and our knowledge of the phase codes. Then, we discuss the impact of the Doppler modulation within the individual pulses and we show how the use of identical sequences (IS) for the phase codes can mitigate the degradation of the retrieval in the range Doppler image. Lastly, we propose two alternative methods that retrieve an unambiguous estimate of the Doppler frequency.