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Range-Angle Estimation for FDA-MIMO System With Frequency Offset

Mengjiang Sun, Peng Chen, Zhenxin Cao

Abstract

Frequency diverse array multiple-input multiple-output (FDA-MIMO) radar differs from the traditional phased array (PA) radar, and can form range-angle-dependent beampattern and differentiate between closely spaced targets sharing the same angle but occupying distinct range cells. In the FDA-MIMO radar, target range estimation is achieved by employing a subtle frequency variation between adjacent array antennas, so the estimation performance is degraded severely in a practical scenario with frequency offset. In this paper, the range-angle estimation problem for FDA-MIMO radar is considered with frequency offsets in both transmitting and receiving arrays. First, we build a system model for the FDA-MIMO radar with transmitting and receiving frequency offsets. Then, the frequency offset is transferred into an equalized additional noise. The noise characteristics are analyzed in detail theoretically, together with the influence on the range-angle estimation. Moreover, since the effect of the transmitting frequency offset is similar to additional colored noise, denoising algorithms are introduced to mitigate the performance deterioration caused by the frequency offset. Finally, Cramér-Rao lower bounds (CRLB) for the range-angle estimation are derived in the scenario with the frequency offsets. Simulation results show the analysis of frequency offset and the corresponding estimation performance using different algorithms.

Range-Angle Estimation for FDA-MIMO System With Frequency Offset

Abstract

Frequency diverse array multiple-input multiple-output (FDA-MIMO) radar differs from the traditional phased array (PA) radar, and can form range-angle-dependent beampattern and differentiate between closely spaced targets sharing the same angle but occupying distinct range cells. In the FDA-MIMO radar, target range estimation is achieved by employing a subtle frequency variation between adjacent array antennas, so the estimation performance is degraded severely in a practical scenario with frequency offset. In this paper, the range-angle estimation problem for FDA-MIMO radar is considered with frequency offsets in both transmitting and receiving arrays. First, we build a system model for the FDA-MIMO radar with transmitting and receiving frequency offsets. Then, the frequency offset is transferred into an equalized additional noise. The noise characteristics are analyzed in detail theoretically, together with the influence on the range-angle estimation. Moreover, since the effect of the transmitting frequency offset is similar to additional colored noise, denoising algorithms are introduced to mitigate the performance deterioration caused by the frequency offset. Finally, Cramér-Rao lower bounds (CRLB) for the range-angle estimation are derived in the scenario with the frequency offsets. Simulation results show the analysis of frequency offset and the corresponding estimation performance using different algorithms.
Paper Structure (11 sections, 2 theorems, 73 equations, 10 figures, 5 tables)

This paper contains 11 sections, 2 theorems, 73 equations, 10 figures, 5 tables.

Table of Contents

  1. Introduction
  2. The System Model of FDA-MIMO Radar
  3. Transmitting Signal Model
  4. Receiving Signal Model
  5. The Noise Characteristics
  6. Signal Processing of Equalized Colored Noise
  7. Whitening Colored Noise with the Fourth-Order Cumulant
  8. Denoising with Atomic Norm Minimization
  9. The CRLB for Range-Angle Estimation
  10. Simulation Results and Analysis
  11. conclusion

Key Result

Proposition 1

The noise caused by the receiving frequency offset will disturb the phase difference among both rows and columns in $\boldsymbol{Y}$. The noise caused by the transmitting frequency offsets will disturb the phase difference between different columns in $\boldsymbol{Y}$, but will not interfere with ph

Figures (10)

  • Figure 1: Diagram of an FDA-MIMO radar.
  • Figure 2: The relative error between the approximated signal matrix and the reference signal matrix.
  • Figure 3: Equalized SNR with a different standard deviation of transmitting frequency offset when $\Delta f = 1$ kHz and $10$ kHz.
  • Figure 4: Equalized SNR with a different standard deviation of receiving frequency offset when $\Delta f = 1$ kHz and $10$ kHz.
  • Figure 5: equalized SNR with different ranges of target.
  • ...and 5 more figures

Theorems & Definitions (4)

  • Proposition 1
  • proof
  • Proposition 2
  • proof