Adaptive transmit array sidelobe control using FDA-MIMO for tracking in joint radar-communications

Abstract In this paper, we present an adaptive closed–loop range-angle dependent sidelobe control using frequency diverse array (FDA) multiple-input multiple-output (MIMO) design for joint radar-communications. The system carries out tracking of the target and the communication receiver, while transmitting information bits towards the intended communication receiver using a flexible sidelobe control, i.e., controlling the power emitted at a certain angle-range position. The range-angle dependent sidelobe control utilizing an overlapped-FDA generated uncoupled beampattern with the proposed Blackman window based non-uniform frequency offsets enables the communication links to use the same radar spectrum. Moreover, we adaptively design two transmit weight vectors and finally compute a beamspace matrix that facilitates to generate the range-angle dependent beam patterns with a same radar main lobe, but distinct sidelobe levels (in accordance with the binary bit to be transmitted) for the moving target and communication receiver, respectively. Furthermore, we propose a cognitive algorithm to discriminate the target and communication receiver positions. Finally, the information bits can be efficiently detected by the intended communication receiver, merely, due to the power difference in sidelobe levels of the directed range-angle dependent radiated patterns without affecting the radar performance. The improved performance of the proposed design is verified in terms of bit error rate and inherent security for the communication functionality, while target detection, target tracking and parameter estimation are considered for the radar application.