Comparison of Correlation-Based OFDM Radar Receivers

Abstract

Various correlation-based receivers have been proposed in passive bistatic and active monostatic radar exploiting orthogonal frequency-division multiplexing (OFDM) communications signals, but too little has been dedicated to establishing their relations and advantages over each other. Accordingly, this paper provides an analytical comparison of the common filters in such waveform sharing scenarios, along with a performance analysis regarding three criteria: computational complexity, signal-tointerference-plus-noise-ratio and resilience to ground clutter. The last two especially assess the possible detrimental effects of the random sidelobes (or pedestal) induced by the data symbols in the range-Doppler map. Although simulations show that none of the filters performs unanimously better, the ones employing circular correlations globally evidence attractive results.

Correlation-Based Radar Receivers with Pulse-Shaped OFDM Signals

“…As proved in [3], range-Doppler maps resulting from the MF (5) and SB (6) receivers in a clutter-free scenario can be expressed as (7) and (8), respectively. w MF and w SB denote the output thermal noise signals and…”

“…With the aim of detecting and estimating the target, (4) is usually represented in the range-Doppler domain 3 . Among the variety of correlation-based receivers that have accordingly been proposed, two stand out [3]. These are recalled hereafter with a normalization factor chosen to ensure the same processing gain for a target at null range and Doppler.…”

“…Symbol-based (SB): The so-called symbol-based radar receiver can be seen as a simplification of the MF relying on (i) an invariant Doppler approximation for each block, (ii) the exploitation of the multicarrier waveform structure, revealing a blockwise FFT-based implementation [3]. It basically consists of the three following stages [6], [8].…”

“…Considering a range-Doppler map χ, we define the output SINR as In our case, the SINR expressions of the MF and SB receivers were shown to result in (12)-(13) [3]. It is worth noting that unlike the MF, in a given scenario, the SB receiver has a uniform SINR in the range-Doppler map.…”

“…From a correlation-based radar receiver viewpoint, the symbols carried by the multicarrier waveform can be seen as a nuisance parameter, inducing a pedestal (or random sidelobes) in the range-Doppler map. While such an interference has been studied in the particular case of cyclic-prefix orthogonal frequency-division multiplexing (CP-OFDM) [3], a generalization to pulse-shaped multicarrier schemes (e.g., FBMC 1 , FMT 2 [4]) is of interest to increase the robustness of DFRC systems towards high-Doppler and/or low signal-to-noise-ratio scenarios [5], [6].…”