Design and analysis of non-uniform MIMO array for interference suppression and automotive applications

Abstract

Automotive radars play a very important role in reduction of traffic accidents and casualties by making the vehicle fully self aware of its surroundings. For the vehicle to be fully self aware multiple sensors or radars have to placed in close proximity of each other on the body of the automobile. This will lead to interference between the radars which results in sub optimal performance of the radar system. Currently most of interference mitigation techniques employ various methods of signal coding algorithms, by assigning each radar a different code or modifying beamforming and angle of arrival algorithms to suppress the interference. Most of theses technique use and exploit the properties of the transmitted signal (signal processing techniques) for mitigating the interference. In this thesis the avenue of antenna array design for mitigation of interference is explored. By modifying the radiation pattern of the array, the antenna array will act as spatial filter against the incoming interference signals. In this thesis two techniques for designing the antenna array with improved radiation pattern are proposed. The design techniques are used to optimize the MIMO virtual array of the radar for low sidelobes and increased aperture, and the optimized virtual array is then factorized to obtain the Tx and Rx arrays. 2 virtual arrays of 12 elements and 24 elements are optimized using the design techniques. The performance of the various designs is ranked based on the output SINR of an adaptive beamformer. The simulations results show that the optimized MIMO arrays result in an improvement of up to 3.5dB in SINR in comparison to the currently used topologies. Finally, a prototype of the improved MIMO antenna system is modeled in CST MS design environment, and the superior performance of the designed array topologies over the existing array topologies is verified.