OFDM-MIMO Radar With Optimized Nonequidistant Subcarrier Interleaving

Abstract

Radar with digitally generated orthogonal frequency division multiplexing (OFDM) signals is an emerging research field that has been studied for the past few years. Another trend for radar is the multiple-input multiple-output (MIMO) architecture used for an efficient direction-of-arrival estimation. These two technologies can be efficiently combined into an OFDM-MIMO radar with novel interleaving concepts enabled by the multicarrier structure of OFDM. By multiplexing of transmit antennas via subcarrier interleaving, the whole bandwidth can be utilized by all transmit antennas simultaneously. In case of equidistant subcarrier interleaving, however, the unambiguously measurable distance range is reduced. To avoid this reduction, we propose an OFDM-MIMO radar concept with nonequidistant subcarrier interleaving (NeqSI) that maintains the full unambiguously measurable distance range. Since the NeqSI leads to sidelobes in distance estimation, we present an approach for generation of near-to-optimum nonequidistant interleaving patterns. To further complement the proposed concept, compressed sensing based distance–velocity estimation algorithm that achieves a high dynamic range in both distance and velocity dimensions is used. We study the performance of the presented concept in simulations and validate it by measurements with an OFDM-MIMO radar prototype.