Smart Antenna System
Smart antennas are antenna arrays or groups of an antenna in which spatial signal signature is identified with smart processing algorithms. A smart antenna source (transmitter), takes advantage of the diversity effect at the destination (receiver), or both in the diversity effect to increase the speed of data and reduce the error rate by transmission and/or reception of multiple radio frequency (RF) waves. Is included. Smart antenna technology can overcome these capacity limitations as well as improve signal quality and allow mobile telephones to operate at low power. A Smart antenna is also known as adaptive array antennas, MIMO, and many antennas.
Smart antennas include many personal antennas and related Signal processors that provide signal transmission and signal reception. The major advantage of using a smart antenna is a decrease in overall system power, a decrease In communication interference, and increase system capacity and improve power efficiency. The smart antenna in the receiver reduces signal loss in a multitude of fading, which means more robust signal quality independent of signal variations due to physical environments and other electromagnetic transmitted interference. For mobile applications, there are fewer dropped calls, better reception in low-signal / no-signal or low zones of the dead zone, bit error rate reduction, handoff reduction, and higher data rates.
“smart” portion. Smart antennas can use either, or both, for the signal transmission Concept
A smart antenna is a digital wireless communication antenna system that takes advantage of the effect of diversity on the source (transmitter), destination (receiver), or both. The variation effect includes transmission and/or reception of multiple radio frequency (RF) waves to increase data speed and reduce error rates. In traditional wireless communication, a single antenna is used at the source, and another single antenna is used at the destination. This is called SISO (single input, single output). Such systems are sensitive to problems caused by the multipath effect. When an electromagnetic field (EM field) meets obstructions such as hills, basins, buildings, and utility wires, the wavefronts are scattered, and thus they adopt multiple paths to reach the destination. Late arrival of scattered parts of the signal causes problems such as fading, cut-out (cliff effect), and intermittent reception (picket fencing). In a digital communication system like the Internet, it can cause a decrease in data speed and an increase in the number of errors. The use of smart antennas can reduce or eliminate the troubles caused by multipath wave propagation.
FUNCTIONS OF SMART ANTENNA
Direction of Arrival Estimation:
Smart antenna systems estimate the direction of the signal’s arrival, such as MUSIC (Multiple Signal Classification), rotational invariance technique (ESPRIT) algorithms, matrix pencil method, or estimation of signal parameters through one of their derivatives. These include finding a spatial spectrum of the antenna/sensor array and calculating DOA from the peaks of this spectrum. These calculations are computationally intensive. Matrix pencil is very efficient in the case of real-time systems and under correlated sources.
This is used to connect the radiation pattern of the antenna array to the phases of signals in the direction of the desired / target mobiles and to nullify the pattern of the target/mobiles which are unwanted/interfering targets. This can be done with a simple FIR tape delay line. The weight of the FIR filter can also be changed favorably and is used to create an optical beam, in the sense that it reduces the MMSE between the desired and actual beam patterns formed. Typical algorithms are the simplest lineages and LMS algorithms. There is an ever-increasing demand on mobile wireless operators to provide voice and high-speed data services. The base stations seek to support more users per user to reduce overall network costs and make services affordable for customers. Consequently, wireless systems that enable high data rates and high capacities are a pressing requirement
 FIG 1: SMART ANTENNA SYSTEM – BEAM FORMING
TYPES OF SMART ANTENNA
There is two type of smart antenna mainly.
Switchable beam antenna systems make many fixed beams with increased sensitivity in particular directions. These antenna systems detect signal strength, select one of several predetermined, fixed beams and switch from one beam to another as the mobile moves throughout the sector. Instead of shaping the directional antenna pattern with the metal properties and physical design of the same element, switched Beam systems combine the output of multiple antennas in such a way as to create granular directional beams with more spatial selectivity with traditional, single-element approaches.
Adaptive Array antennas:
Adaptive antenna technology represents the most advanced smart antenna approach to date. Using a variety of new signal-processing algorithms, the adaptive system takes The advantage of its ability to effectively find and track different types of signals to effectively minimize interference and maximize intended signal reception. Both systems attempt to increase the gain according to the user’s location, however, only the adaptive system provides optimal gain while simultaneously detecting, tracking and minimizing the signal. Another way to classify smart antennas is the number of inputs and outputs that are used for the device. The categories according to this classification are given below.
1. SIMO (Single Input – Multiple Output)
In this method, one antenna will be used at the source and several antennas will be used at the destination.
2. MISO (Multiple Input – Single Output)
In this method, multiple antennas will be used at the source and only one antenna will be used at the receiver.
3. MIMO (Multiple Input – Multiple Output)
In this method many antennas will be used for both sour and destination. This is the most efficient method among all. This method was recently extended according to the IEEE 802.11n standard. This method explicitly supports spatial Information process.
This paper gives a brief idea about the smart antenna systems and their types we are using to avoid multiple and co-channel interference. These antennas have advance characteristics such as higher efficiency, higher reliability than normal antennas. By using this idea we can make any antenna efficient to provide signal to the preferred user and by doing that the strength of the signal can be increased. We can also use it in Wi-Fi, Radio signals and many more.
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