Background

The vast literature on the multi-input multi-output (MIMO) radar with widely separated antennas ignores the non-orthogonality of the received signals from different transmitters [1]. In practice, this orthogonality cannot be achieved for all delay and Doppler pairs [2].

Our Research

We show the sensitivity of the MIMO radar target detection performance to the non-orthogonality of the received signals from different transmitters [3] [4].

· Presented a measurement model for a MIMO radar with widely separated antennas considering the cross-correlation of the received signals from different transmitters as unknown deterministic parameters

· Proposed an EM based algorithm to estimate the unknown cross-correlation terms and target and noise parameters..

· Developed a Wald test to detect the presence of a target.

· Computed the Cramér-Rao bound on target power estimation error and used it to obtain the asymptotical statistical distribution of the detection test.

· Demonstrated quantitatively the sensitivity of the MIMO radar to changes in the unknown cross-correlation levels (average cross-correlation levels (ACCL)), using both the asymptotic analysis of the Wald test and numerical examples.

We demonstrate that as the ACCL increases, the detection performance deteriorates. Moreover, MIMO radars with more transmitters and/or receivers have better detection performance, but they are more sensitive to the changes in the cross-correlation values. Our results are important to evaluate the realistic performance of the MIMO radar in practice, and to design radar waveforms with desired cross-correlations to achieve the estimated detection performance.

Figure 1: Probability of detection vs. signal-to-noise ratio (SNR) for different ACCL values (probability of false alarm , PFA=0.01).

Figure 2: Probability density function of the test statistics under H₁ for different ACCL values and (a) MIMO 2 × 3 (b) MIMO 3 × 3 (c) MIMO 3 × 5 configurations.

Figure 3: Receiver operating characteristics of the target detector for different ACCL values and (a) MIMO 2 × 3 (b) MIMO 3 × 3 (c) MIMO 3 × 5 configurations.

References

1- J. Li and P. Stoica, MIMO Radar Signal Processing. Wiley-IEEE Press, Oct. 2008.

2- Y.I. Abramovich and G.J. Frazer, “Bounds on the volume and height distributions for the MIMO radar ambiguity function,” IEEE Signal Processing Letters, vol.15, pp.505-508, 2008.

3- M. Akcakaya and A. Nehorai, "MIMO radar sensitivity analysis for target detection," 2011 IEEE Radar Conference, Kansas City, KS, USA, May 23-27, 2011, pp. 633-638.

4- M. Akcakaya and A. Nehorai, "MIMO radar sensitivity analysis for target detection," IEEE Trans. on Signal Processing, vol. 59, no. 7, pp. 3241-3250, Jul. 2011.