Research On High Resolution DOAAlgorithms Of Smart Antennas

With the rapid development of wireless communications, the accompanied problems are also increasing, Such as high communication quality、high speed data rate、large channel capacity and the interference between the large number of users and etc. The existing wireless technology has been proved to be unable to solve these problems, However, The smart antenna technology proved to be a feasible method. This technology can significantly reduce the interference between the users, meantime, improving spectrum efficiency and system capacity. The technology has been widely used, for example, in Datang Mobile launched TD-LTE technology, which adopted smart antenna technology.In smart antenna technology, the most important and critical is the part of digital processing, which includes the arriving direction estimation of the coming waves in uplink and the beam forming in downlink. Spatial spectrum estimation method is an important research direction in the DOA method in recent years, This paper analyzes some classic spatial spectrum algorithms, and made some improvements to the inadequacies of these algorithms in order to achieve higher accuracy, Specifically as follows:First, the paper provides an overview of the research background and its significance, and an overview of the current development of the smart antenna.Second, the paper describes the theoretical basis of the smart antenna, especially makes a detailed analysis of the working principle of the smart antenna and smart antenna array model, to make preparations for the DOA algorithm followed.Third, introduce the development of the traditional DOA algorithm, and make detailed theoretical analysis of some of these algorithms, the simulation comparison are also presented. In particular, the focus points to subspace methods (MUSIC algorithm),to make preparations for the method as presented below. Four, introduce the commonly used spatial smoothing MUSIC technology, but its shortcoming is hard to distinguish between small interval signals and loss of aperture, thus, an improved MUSIC algorithm is put based on Toeplitz. The method not only has the advantages of spatial smoothing MUSIC technology,which is of good resolution on strong signals, in the meantime, it makes up the shortcomings of spatial smoothing MUSIC that has low resolution on small interval signals、aperture loss and high complexity algorithm. The simulation results also verified the validity of the method.Five, Propose a new DOA estimation method using pilot signal, which is different with previous DOA method. Its DOA estimation is after beam forming. The method has higher resolution, and can distinguish the number of wave numbers of signals greater than the number of array elements. Then apply this method in uniform circular array which not only has the advantage of uniform circular array, but also have the advantages of the method.Last, through summarizing and reviewing the work of this paper, put what to be completed and improved, and prospects of the next step work plan.