| Colocated multiple input multiple output(MIMO)radar transmits different waveforms through multiple emitting antennas,and employs multiple antennas to receive echoes for achieving target detection.Compared with the traditional phased array radar,colocated MIMO radar possesses more degrees of freedom at the transmitting and processing ends due to its advantages in waveform diversity,and has excellent performance in terms of target detection,parameter estimation,and anti-jamming etc.,which has become an international front and hotspot in the field of radar research.MIMO radar waveform diversity design technology is one of the core technologies of MIMO radar system,aiming to enhance the detection performance by optimizing MIMO radar waveform according to the optimization criteria such as target detection,parameter estimation or anti-interference performance with reference to different tasks,environments and resource constraints.The uses of a large number of military and civilian electronic equipment and the complex non-uniform time-varying geographical environment,make the detection environment of traditional radar more and more complex,which seriously affects the detection performance of weak targets.Therefore,it is of great significance and challenge to design MIMO radar waveform to enhance detection performance in the complex electromagnetic environment such as electromagnetic spectrum compatibility and geographic clutter.To this end,this dissertation studies the theories and methods of MIMO radar waveform design in spectrum compatibility or clutter environment,and the main innovations are as follows:1.To solve the design of narrow-band MIMO radar transmit beampattern,a waveform design algorithm based on coordinate descent(CD)is proposed to effectively trade-off the performance between transmit beampattern and waveform ambiguity function by forcing the waveform similarity constraint.A waveform design algorithm based on sequence alternating direction multiplier method(SADMM)is proposed,which can compromise MIMO radar beampattern performance and spectrum compatibility ability by imposing waveform spectrum constraint.2.To solve the design of wideband MIMO radar transmit beampattern,waveform design algorithms based on nested iterative optimization algorithm(NIOA)and nested sequencial alternating direction multiplier method(NSADMM)are proposed.By minimizing the weighted sum of beampattern template matching error and spacialfrequency stopband energy under waveform modulus constraint,the performance contradiction between MIMO radar beampattern performance and spectrum compatibility ability is effectively balanced.3.To solve the problem of robust MIMO radar target detection in the presence of clutter,waveform design algorithms based on Dinkelbach based CD(DA-CD)and CD are proposed.By maximizing the worst-case signal-to-interference-noise ratio(SINR)under waveform similarity constraint,the target detection is improved under the inaccurate knowledge of signal-dependent clutter,and the pulse compression characteristics is also ensured.4.To solve the problem of MIMO radar moving target detection in the presence of clutter,the joint design algorithms of transmit waveform and receive filter based on block CD(BCD)and sequencial greedy optimization(SGO)are proposed.By maximizing the SINR under waveform similarty constraints,the detection performance of slow target embedded into range ambiguous clutter is effectively improved,at the same time,the designed waveform has good waveform ambiguity function features.5.To solve the problem of MIMO radar multiple target detection in the presence of clutter,the joint design algorithms of transmit waveform and receive filter bank based on nested iteration convex enhancement(NICE)and nested modified iteration convex enhancement NMICE are proposed.By maximizing the worst-case SINR under waveform spectrum constraint,the detection performance of multiple targets in the presence of signal-dependent clutter is effectively improved,and the spectrum coexistence ability between MIMO radar and other electronic systems is guaranteed.The theoretical performance,convergence and computational complexity of the above algorithms have been verified by theoretical analysis and simulation.The results show that the proposed models and methods can effectively control the performance of MIMO radar in complex electromagnetic environment,in terms of the transmit beampattern,electromagnetic compatibility,target detection,waveform ambiguity function and etc. |
