Study Of Orthogonal Wave Form Based On Phase-Coding Method

MIMO (multiple-input-multiple-output) radar has become really popular in radar areas because of its creative system and outstanding performances. Comparing to traditional phased-array radar, MIMO radar has great advantages and more characteristics. MIMO radar has bigger time-band, better ability of anti-interference and better ability of anti-interception. These characteristics guarantee the research of MIMO radar meaningful.The waveform design of MIMO radar is a major research topic of the centralized MIMO radar. Different from the traditional radar waveforms, MIMO radar waveforms are consists of several orthogonal coherent waveforms. In order to distinguish different targets at the same angle, the auto-correlation properties must be guaranteed. At the same time, in order to decrease interferences of different echo waves, the cross-correlation properties must be guaranteed as well.This thesis proposed two innovations aiming at designing the MIMO radar waveforms with good auto-correlation and cross-correlation properties.(l)While using GA(genetic algorithm) to generate orthogonal poly-phase codes, different encoding methods and operators are tried and compared. It indicates that different operators and encoding methods of GA have big influence on the properties of codes that generated eventually. Aiming at the specific problems of this thesis, best operator and encoding method are chosen afterwards.(2)The hybrid algorithm of GA and Immune Algorithm is used to generate MIMO radar waveforms. GA is based on decent theory system, and has great ability of global search, while the memory system and population regeneration function of Immune Algorithm can fix the flaws of bad local search ability and slow computing speed existed in GA, and these problems are essential in generating orthogonal polyp-phase codes. At the same time, the properties of parameters and Doppler performances of codes generated are also analyzed afterwards. After comparing to other relative papers, it indicates that the hybrid algorithm can generate poly-phase codes with decent properties of auto-correlation and cross-correlation.Above all, this thesis emphasize on choosing and designing proper algorithm to design orthogonal poly-phase codes mainly used for MIMO radars. By specific introduce of the code-designing process, this thesis develops the performance of the algorithm, and the mixed algorithm proposed in this thesis is proved by simulations and comparison to be outstanding somehow.