MASTER THESIS A Study of Implementation of Digital Signal Processing for Adaptive Array Antenna

PREFACE An adaptive array antenna technology is paid attention to a lot of applications in the next generation wireless mobile communications. This technology can form a beam pattern at an intended direction by applying digital signal processing algorithms to the digitized signals from each antenna element. It has had some barriers in commercial uses due to implementation complexities and impractically high costs, but advances in digital device technologies have led to solve the implementation difficulties due to the nonlinearity of an analog device with a digital signal processing. This paper describes the development of an evaluation prototype system for adaptive array antenna test bed to realize reasonable cost and high performance. And then it presents the examination of their applications. This paper consists of 3 main parts: first, a design of digital prototype system; second, a beamforming antenna as an application; third, a DOA (Direction Of Arrival) estimation system as the other application. In Chapter 2 the hardware configuration and the design of the digital prototype board that we developed considering the architecture of software defined radio (SDR) are described. In Chapter 3 and Chapter 4 the examinations of the application implementation using this prototype system are discussed. Chapter 3 presents the beamforming technique by MRC (Maximum Ratio Combining). It recombines the output power at maximal ratio by co-phasing received signals at each element like a phased array antenna. In this chapter, the circuit implementation details and the experimental results are presented. The digital calibration methods of errors in adaptive array antenna system caused by non-ideal antenna pattern, mutual coupling between each element and etc are proposed and the circuit implementations of them are also presented. On the other hand, Chapter 4 deals with the implementation issue of DOA estimation problem. As a matter of fact, it is significant to recognize previously the transmission conditions and the environment of radio wave so as to model a multi-signal propagation efficiently and form beampattern properly. Moreover to form beams at some directions, most of beamforming algorithms need the knowledge of DOAs of incident waves in advance. Generally the DOA algorithm is very complex and has heavy computational load. From this point of view, the high performance DOA estimation system is very useful in the array antenna technology. In Chapter 4 the hardware implementation of MUSIC (MUltiple SIgnal Classification) method, a super-resolution DOA estimation method, is discussed. Especially the EVD (Eigen Value Decomposition) …