Research On Adaptive Array Antenna Tracking And Anti-jamming Algorithm

High-speed movement of fast train restricts the development of mobile communications in high-speed railway system. In this paper, stratospheric communication platform is used to solve the fast handover problem, and adaptive array antenna technology is used for target tracking. The research work focuses on target recognition among the coherent sources and suppression of the interference signals by using adaptive algorithm. The major work can be organized as follows:1. The significance and demands of high-speed railway mobile communications are investigated. According to the existing problems and current solutions, we propose a stratospheric communication platform as a relay of high-speed railway mobile communications by using array antenna to track the fast train moving.2. To select an appropriate array antenna model, different kinds of array antenna models are researched and compared. Finally, uniform circular array is chosen for the research objective. To identify the research scenarios, we also set up the signal model. The concepts of coherent signals and related signals are defined to lay the foundation of anti-coherence.3. To overcome the limitations of classical DOA estimation algorithms in terms of anti-coherence, a spatial smoothing algorithm with capability of anti-coherence is applied. For the reason that the spatial smoothing algorithm is not applicable for circular arrays, virtual linear transformation is put forward in this paper, so that the DOA estimation for coherent sources is implemented by a circular array.4. To effectively suppress the interference signals and enhance the desired signal, regular beamforming algorithms and adaptive beamforming algorithms are researched. On the other hand, the method of transforming domain is used to optimize algorithm performance, which not only accelerates the convergence rate, but also enhances the anti-coherence ability. On this basis, an adaptive algorithm of variable step size in frequency domain is proposed to further enhance the performance of the algorithm.5. To trackle tracking the high speed train and surppressing the interference, a model of fast train movement under coverage of the stratospheric communication platform is built and analyzed. Two kinds of tracking and anti jamming schemes are researched by using DOA estimation and reference signal. The schemes are simulated and compared with advantages and disadvantages.