Signal & Image Processing : An International Journal (SIPIJ) Vol.3, No.5, October 2012 DOI : 10.5121/sipij.2012.3505 57          Sai Suhas Balabadrapatruni Dept. of Electronics & Communication Engineering, JNT University, Hyderabad, India saisuhas.b@gmail.com ABSTRACT This paper presents the performance analysis of directions of arrival estimation techniques, Subspace and the Non-Subspace methods. In this paper, exploring the Eigen-analysis category of high resolution and super resolution algorithms, presentation of description, comparison and the performance and resolution analyses of these algorithms are made. Sensitivity to various perturbations and the effect of parameters related to the design of the sensor array itself such as the number of array elements and their spacing are also investigated. The analysis is based on linear array antenna and the calculation of the pseudo spectra function of the estimation algorithms. Algorithms namely Delay-and-sum, Capon’s, MUSIC, and ESPRIT Direction Of Arrival Estimates. MATLAB™ is used for simulating the algorithms. KEYWORDS Array antenna, Direction of Arrival Estimation, Subspace & Non-Subspace methods, Pseudo Spectrum. 1. INTRODUCTION The need for Direction-of-Arrival estimation arises in many engineering applications including wireless communications, radar, radio astronomy, sonar, navigation, tracking of various objects, rescue and other emergency assistance devices. In its modern version, DOA estimation is usually studied as part of the more general field of array processing. Much of the work in this field, especially in earlier days, focused on radio direction finding – that is, estimating the direction of electromagnetic waves impinging on one or more antennas [1]. Due to the increasing over usage of the low end of the spectrum, people started to explore the higher frequency band for these applications, where more spectrums is available. With higher frequencies, higher data rate and higher user density, multipath fading and cross- interference become more serious issues, resulting in the degradation of bit error rate (BER). To combat these problems and to achieve higher communication capacity, smart antenna systems with adaptive beam forming capability have proven to be very effective in suppression of the interference and multipath signals [2]. Signal processing aspects of smart antenna systems has concentrated on the development of efficient algorithms for Direction-of-Arrival (DOA) estimation and adaptive beam forming. The recent trends of adaptive beam forming drive the development of digital beam forming systems [3]. Instead of using a single antenna, an array antenna system with innovative signal processing can enhance the resolution of DOA estimation. An array sensor system has multiple sensors distributed in space. This array configuration provides spatial samplings of the received waveform. A sensor array has better performance than the single sensor in signal reception and parameter estimation [4].