MIMO radars use multiple transmitters that are transmitting simultaneously. The diversity achieved with several active transmitters can be beneficial for target detection and target parameter estimation, especially for stealth targets and other targets of low observability. However, the use of multiple transmitters places constraints on the transmitted signals and also makes designing the receivers more challenging. With the need of cooperating radars likely to increase in the future, it is important to be able to properly design and optimize this type of radar systems. Methods for the optimization of the transmitters and the receivers of a MIMO radar system and the optimal use of the received signals are developed in this thesis. Several methods for target detection, target parameter estimation, resource allocation, waveform design, and receiver filter design of the MIMO radars are proposed in this thesis. Analysis and numerical results show that the proposed methods lead to improved performance. In target detection, optimal detectors are derived for the Swerling scattering models while also assuming correlated scattering. The impact of the scattering model is also studied for different distributed MIMO radar configurations in detection and estimation tasks. For unknown scattering statistics, a parametric model is developed for improving the detection performance. Methods to optimize the transmit power allocation for target detection with distributed MIMO radar are also provided. A novel algorithm for optimizing the transmit waveform codes is developed. The performance of this algorithm is demonstrated with numerical examples. A spatial coding method is also proposed for improving the channel estimation in colored noise and interference. As most radar use digital signal processing in which the received signal is sampled, it is important to understand the impact of the sampling on the received waveforms. It is shown both analytically and with examples that it is important to take the sampling rate into account at the waveform design phase. Receiver filter designs are developed for situations with both negligible and significant Doppler shifts. The proposed filter design minimizes the noise and interference power while maintaining sidelobe and cross-correlation at tolerable levels. A good trade-off can be achieved between narrowband interference attenuation and sidelobe and cross-correlation levels. A filter optimization formulation for suppressing clutter is also provided. Furthermore, In order to understand jamming threat and develop jamming avoidance methods, the optimization of the worst-case jamming signal for disrupting a MIMO radar system is studied. The results confirm the resilience of distributed MIMO radars against jamming.
|Translated title of the contribution||Lähettimien ja vastaanottimien optimointi ketterissä MIMO-tutkissa|
|Publication status||Published - 2017|
|MoE publication type||G5 Doctoral dissertation (article)|
- MIMO radars
- transmit waveform codes