Experimental Evaluation of Exotic MIMO Radar Transmission and Receive Processing Techniques

The digital revolution has enabled the greater radar community to shift from traditional analog RF subsystems to fully digital architectures. This evolution has led to an increased focus on exotic frameworks like multiple-input multiple-output (MIMO) configurations that trade increased complexity for better performance. Such systems can transmit multiple signals with pre-determined correlation properties, granting superb waveform diversity which offers improved customizability in beampattern design and extended application of adaptive techniques for parameter estimation and target detection.

Taking advantage of the added freedom allowed by diverse transmission, a novel emission design of optimized FM waveforms is derived, statistically analyzed, and experimentally evaluated in this work. This unique framework was developed to test the art of the possible with respect to MIMO emissions from a uniform circular array. An emphasis was placed on the synthesis of orbital angular momentum (OAM) both explicitly and naturally via comparison of two emission-design cases. Furthermore, the feasibility of the optimized waveforms was evaluated through open-air experimentation, using the Waveform Diversity Experimentation System (WaDES) MIMO radar testbed. This led to the conclusion that signals carrying OAM can be used for high-power radar operation, providing a new basis for modulating UCA MIMO emissions.

By exploiting the additional degrees-of-freedom offered by spatially diverse emissions, adaptive receive processing techniques can also be applied to the MIMO radar framework. In this context, the space-range adaptive processing (SRAP) algorithm, which presents distinctive super-resolution capabilities via a reiterative minimum mean-square error (RMMSE) architecture, is demonstrated for both loopback-captured and open-air collected data. This experimental evaluation provides a true performance baseline for SRAP when applied to independent MIMO operation using uniform linear arrays.