High Range and Doppler Resolution by Application of Compressed Sensing Using Low Baseband Bandwidth OFDM Radar

Abstract

Multi-carrier waveforms such as orthogonal frequency-division multiplexing (OFDM) found their way into radar applications in the last few years. However, currently, typically only a fraction of the large baseband bandwidth required to obtain high resolution is available in practice due to hardware limitations. In this paper, we propose a frequency agile sparse OFDM radar processing which allows the transmission of consecutive bandwidth-reduced OFDM pulses on different carriers and thereby covering a much larger measurement bandwidth in a measurement frame. Through joint processing of multiple narrowband pulses and compressed sensing methods, high resolution and unambiguity in the joint range-velocity profile is obtained comparable to an equivalent wideband OFDM. It shows that a baseband bandwidth of 20 % of the full channel bandwidth is sufficient to reliably obtain the same result as for an equivalent wideband OFDM signal. The proposed processing scheme is validated using simulations and radar measurements at 77 GHz.

Automotive Radar — From First Efforts to Future Systems

“…Current research has addressed this topic and sophisticated radar system concepts have been introduced, reducing the enormous data rates by different types of subsampling like introducing steps of the carrier frequency, see Fig. 15 from [70], [71] or the use of compressed sensing [72].…”

“…In [74]- [76], frequency agile radars with reduced bandwidth are proposed that use CS instead of a matched filter compression. In [72], it is shown that only 20% of the resolution bandwidth is sufficient to accurately recover targets.…”

Interference-Robust Processing of OFDM Radar Signals Using Compressed Sensing

“…For OFDM radar, CS is suggested for channel estimation in passive radar application [10], or reconstruction of missing subcarriers [6][11] [12]. Furthermore, CS plays an essential role in signal evaluation of random frequency agile OFDM [13] [14]. Frequency agile OFDM concepts combine a reduced instantaneous baseband bandwidth with an agile carrier frequency to synthesize a wider band over the signal frame as a major bottleneck for OFDM implementation is the sampling rate limitation caused by the affordable consumer hardware at both transmitter and receiver.…”

“…Frequency agile OFDM concepts combine a reduced instantaneous baseband bandwidth with an agile carrier frequency to synthesize a wider band over the signal frame as a major bottleneck for OFDM implementation is the sampling rate limitation caused by the affordable consumer hardware at both transmitter and receiver. The agile carrier frequency can be either chosen deterministically and periodically in a stepped pattern [15] or randomly [14]. Random signal patterns preserve unambiguities and are particularly suitable for the application of CS-based signal evaluation.…”

Effort Considerations of Compressed Sensing for Automotive Radar

“…The concept of compressed sensing [1], [2] was introduced in automotive radar for various tasks. Possible examples are an enhanced angular [3] or range-Doppler resolution as in [4]. In both cases samples are missing which are restored with compressed sensing algorithms.…”