Analysis of smart antenna with improved signal quality and spatial processing

Abstract

One of the prominent techniques used to mitigate the electromagnetic energy radiation (which causes interference in the signal transmission) is smart antenna. The smart antenna system remains the noticeable dynamic approach employed to develop the power output of the signal of interest in a specified direction and reduce the interfering signal power in unnecessary direction. Smart antenna system comprises of an arrangement of multiple numbers of antenna elements whose signals are logically connected to utilize the two-dimensional (2-D) domain and enhance the efficiency of a wireless communication system. This research work emphasis on how the smart antenna can adaptively optimize the signal to noise ratio (SNR) of multiple antenna arrays in an arbitrary location and a specified direction of signal. Adaptive array technique using Applebaum array algorithm is considered in this work. The method is practical in the implementation, used in interference rejection. Phase arrays cannot proffer the potential of steering nulls in the direction of discarded users. In order to improve a precise action of a communication channel adaptively, a measure such as signal to noise ratio and dynamic range must be adopted. The received signal of the proposed antenna arrays are adapted and aligned in magnitude and phase. The sidelobe canceler is calculated with Applebaum array algorithm with analytical values of α = 0.23 and β = 0.01. The interfering signal applied to the antenna array at evenly separated angles from −90° to +90° in unit increments. The interference power calculated is 2.5 dB. The resultant interference suppression (experimental) in the array is confirmed. The utmost interference suppression receiving at ±90° is 10.0 dB. The ideal weights of an adaptive antenna array, which exploits the output signal to noise ratio without inaccuracies, are generally calculated with the aid of array correlation matrix of steering vector and noise in a specified track. A smart antenna is spatially sensitive and has inherent intelligence to create a beam with high gain in the preferred direction. It can change the beam pattern actively and can find and track the users as necessary. Smart antenna can adaptively optimize the SNR of multiple antenna arrays in an arbitrary location and a specified direction of signal. This can be done through adaptive array technique using Applebaum array algorithm. The Applebaum algorithm maximizes the SNR, but under the assumption that the desired signal is absent most of the time, as in a pulsed radar [1, 2]. Spatial filtering is accomplished in an adaptive array by automatically sensing the direction of arrival of an interference source and forming a (retrodirective) beam in that direction to subtract from the original (unadapted) beam pattern. The idea of subtracting a retrodirective beam (having an amplitude and phase that matches the unadapted beam) from the unadapted beam response to obtain an overall beam null in the direction of an interference source [3].