  We propose in this work a radar detection system for orthogonal-frequency
division multiplexing (OFDM) transmission. We assume that the transmitting
antenna Tx is colocated with a monostatic radar. The latter knows the
transmitted signal and listens to echoes coming from the reflection of fixed or
moving targets. We estimate the targets parameters (range and velocity) using a
2D-Periodogram. Moreover, we improve the estimation performance in low signal
to noise ratio (SNR) conditions using the discrete Fourier transform channel
estimation (DFT-CE) and we show that Zadoff-Chu precoding (ZCP) adopted for
communication, does not degrade the radar estimation in good SNR conditions.
Furthermore, since the dimensions of the data matrix can be much larger than
the number of targets to be detected, we propose a sparse Fourier transform
based Fourier projection-slice (FPS-SFT) algorithm to reduce the computational
complexity of the 2D-Periodogram. An appropriate system parameterization in the
77GHz industrial, scientific and medical (ISM) band, allows to achieve a range
resolution of 30.52 cm and a velocity resolution of 0.67 m/s and to reduce the
periodogram computation time up to around 98.84%.
