TECHNICAL SEMINAR REPORT

SMART ANTENNA

NAME BHARATH KUMAR V

USN 1PE10EC019

VISVESVARAYA TECHNOLOGICAL UNIVERSITY

Belgaum-590014

Seminar Report

On

SMART ANTENNA Submitted in partial fulfillment of the requirements for the VIII Semester

Bachelor of Engineering

IN

ELECTRONICS AND COMMUNICATION ENGINEERING

For the Academic year

2013-2014

BY

BHARATH KUMAR V

1PE10EC019 UNDER THE GUIDANCE OF

Professor KAILASHNATH

Dept. of ECE, PESIT, BSC.

Department of Electronics and communication Engineering

PESIT, Bangalore South Campus HOSUR ROAD BANGALORE-560100

PESIT, Bangalore South Campus HOSUR ROAD

BANGALORE-560100

DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING

CERTIFICATE

This is to certify that the seminar entitled SMART ANTENNA is

a bonafide work carried out by BHARATH KUMAR V bearing register

number 1PE10EC019 in partial fulfillment for the award of Degree of

Bachelors (Bachelors of Engineering) in Electronics and Communication

Engineering of Visvesvaraya Technological University, Belgaum during the

year 2013-2014.

Signatures:

Seminar Guide Head of the Dept

Mr.Kailashnath Dr. Subhash Kulkarni HOD, ECE

PESIT, BSC

Bangalore-100

Examiners:

1.

2.

Dept. of E&C PESIT-BSC

Index

Sl. No. Topic Page No.

1.

2.

3.

4.

5.

6.

ABSTRACT

1:- Introduction

2:- Antenna and Antenna Systems

2.1:-Antenna

2.1.1:- Omnidirectional Antenna

2.1.2:- Directional Antenna

3:-Smart Antenna.

3.1:- Introduction of Smart Antenna

3.2:- History of Smart Antenna

3.3:- Types of Smart Antenna

3.3.1:- Adaptive Array

3.3.2:- Switched Beam

3.4:- Relative Benefits of Switched Beam and

Adaptive Array Systems

3.5:- Working of Smart Antenna

3.6:- Categories of Smart Antenna.

3.7:- Function of Smart Antenna

3.7.1:- Beamforming

3.7.2:- Direction of Arrival(DOA)

3.8:- Parameters affecting Antenna performance

3.9:- Applications of Smart Antenna.

3.10:- Advantages and Disadvantages of Smart

Antenna.

3.11:- Features and Benefit of Smart Antenna

4:- Conclusion

References

1

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1. Introduction

Wireless Communication is growing with a very rapid rate for several

years. The progress in radio technology enables new and improved

services. Current wireless services include transmission of voice, fax and

low-speed data. More bandwidth consuming interactive multimedia

services like video-on demand and internet access will be supported in

the future.

Wireless systems that enable higher data rates and higher capacities are

a pressing need. Wireless networks must provide these services in a wide

range of environments, dense urban, suburban, and rural areas.

Because the available broadcast spectrum is limited, attempts to increase

traffic within a fixed bandwidth create more interference in the system

and degrade the signal quality.

The solution to this problem is SMART ANTENNA. Today's modern

wireless mobile communications depend on adaptive "smart" antennas to

provide maximum range and clarity. With the recent explosive growth of

wireless applications, smart antenna technology has achieved widespread

commercial and military applications.

There is an ever-increasing demand on mobile wireless operators to

provide voice and high-speed data services. At the same time, operators

want to support more users per basestation in order to reduce overall

network cost and make the services affordable to subscribers. As a

result, wireless systems that enable higher data rates and higher

capacities have become the need of the hour.

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2. Antenna and Antenna System 2.1 – Antenna

An antenna (or aerial) is a transducer designed to transmit or receive

electromagnetic waves. In other words, antennas convert electromagnetic

waves into electrical currents and vice versa. Antennas are used in

systems such as radio and television broadcasting, point-to-point radio

communication, wireless LAN, radar, and space exploration. Antennas

are most commonly employed in air or outer space, but can also be

operated under water or even through soil and rock at certain

frequencies for short distances.

Physically, an antenna is simply an arrangement of one or more

conductors, usually called elements in this context. . In transmission, an

alternating current is created in the elements by applying a voltage at the

antenna terminals, causing the elements to radiate an electromagnetic

field. In reception, the inverse occurs: an electromagnetic field from

another source induces an alternating current in the elements and a

corresponding voltage at the antenna's terminals. Some receiving

antennas (such as parabolic types) incorporate shaped reflective surfaces

to collect EM waves from free space and direct or focus them onto the

actual conductive elements.

There are two fundamental types of antenna directional patterns, which,

with reference to a specific three dimensional (usually horizontal or

vertical) plane are either:

1. Omni-directional (radiates equally in all directions), such as a

vertical rod.

2. Directional (radiates more in one direction than in the other).

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2.1.1- Omnidirectional Antenna

Omni-directional usually refers to all horizontal directions with reception

above and below the antenna being reduced in favor of better reception

(and thus range) near the horizon.

Since the early days of wireless communications, there has been the

simple dipole antenna, which radiates and receives equally well in all

directions. To find its users, this single-element design broadcasts

omnidirectionally in a pattern resembling ripples radiating outward in a

pool of water. While adequate for simple RF environments where no

specific knowledge of the users' whereabouts is available, this unfocused

approach scatters signals, reaching desired users with only a small

percentage of the overall energy sent out into the environment.

Figure 2.1:- Omnidirectional Antenna and Coverage Patterns

Given this limitation, omnidirectional strategies attempt to overcome

environmental challenges by simply boosting the power level of the

signals broadcast. In a setting of numerous users (and interferers), this

makes a bad situation worse in that the signals that miss the intended

user become interference for those in the same or adjoining cells.

In uplink applications (user to base station), omnidirectional antennas

offer no preferential gain for the signals of served users. In other words,

Users have to shout over competing signal energy. Also, this single-

element approach cannot selectively reject signals interfering with those

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of served users and has no spatial multipath mitigation or equalization

capabilities.

Omnidirectional strategies directly and adversely impact spectral

efficiency, limiting frequency reuse. These limitations force system

designers and network planners to devise increasingly sophisticated and

costly remedies. In recent years, the limitations of broadcast antenna

technology on the quality, capacity, and coverage of wireless systems

have prompted an evolution in the fundamental design and role of the

antenna in a wireless system.

2.1.2- Directional Antenna

A "directional" antenna usually refers to one focusing a narrow beam in a

single specific direction. A single antenna can also be constructed to have

certain fixed preferential transmission and reception directions. As an

alternative to the brute force method of adding new transmitter sites,

many conventional antenna towers today split, or sectorize cells. A 360°

area is often split into three 120° subdivisions, each of which is covered

by a slightly less broadcast method of transmission.

All else being equal, sector antennas provide increased gain over a

restricted range of azimuths as compared to an omnidirectional antenna.

This is commonly referred to as antenna element gain and should not be

confused with the processing gains associated with smart antenna

systems.

While sectorized antennas multiply the use of channels, they do not

overcome the major disadvantages of standard omnidirectional antenna

broadcast such as co-channel interference

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All antennas radiate some energy in all directions in free space but

careful construction results in substantial transmission of energy in a

preferred direction and negligible energy radiated in other directions.

Figure 2.2 –

Directional Antenna and Coverage Pattern

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3. Smart Antenna

3.1- Introduction of Smart Antenna

Contrary to the name smart antennas consist of more than an antenna.

“A Smart Antenna is an antenna system which dynamically reacts to its

environment to provide better signals and frequency usage for wireless

communications”. There are a variety of smart antennas which utilize

different methods to provide improvements in various wireless

applications. This report aims to explain the main types of smart

antennas and there advantages and disadvantages.

The concept of using multiple antennas and innovative signal processing

to serve cells more intelligently has existed for many years. In fact,

varying degrees of relatively costly smart antenna systems have already

been applied in defense systems. Until recent years, cost barriers have

prevented their use in commercial systems. The advent of powerful low-

cost digital signal processors (DSPs), general-purpose processors (and

ASICs), as well as innovative software-based signal-processing techniques

(algorithms) have made intelligent antennas practical for cellular

communications systems.

Today, when spectrally efficient solutions are increasingly a business

imperative, these systems are providing greater coverage area for each

cell site, higher rejection of interference, and substantial capacity

improvements.

Dept. of E&C PESIT-BSC

Fig 3.1:- Smart Antenna System

Figure 3.2- Block Diagram of Smart Antenna

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3.2- History of Smart Antenna

Early smart antennas were designed for governmental use in military

applications, which used directed beams to hide transmissions from an

enemy. Implementation required very large antenna structures and time-

intensive processing and calculation.

As personal wireless communications began to emerge, it was evident

that interference in wireless networks was limiting the total number of

simultaneous users the network could handle before unacceptable call

quality and blocking occurred. Since the narrow beams of the early

governmental smart antennas created less overall interference,

researchers began to explore the possibility of extending the use of smart

antennas to reduce overall network interference in commercial wireless

networks, thus increasing the total number of users a wireless system

could handle in a given block of spectrum. But the hardware and

processing technologies required to perform the complex calculations in

the very small spaces of time available in personal wireless

communications would prove to be a hurdle that was extremely difficult

to overcome. A few select companies have successfully developed and

introduced smart antenna technologies into commercial wireless

networks.

Antennas were used in 1888 by Heinrich Hertz (1857-1894) to prove the

existence of electromagnetic waves predicted by the theory of James

Clerk Maxwell. Hertz placed the emitter dipole in the focal point of a

parabolic reflector.

The origin of the word antenna relative to wireless apparatus is attributed

to Guglielmo Marconi. In 1895, while testing early radio apparatus in the

Swiss Alps, Marconi experimented with early wireless equipment.

A 2.5 meter long pole, along which was carried a wire, was used as a

radiating and receiving aerial element . Until then wireless radiating

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transmitting and receiving elements were known simply as aerials or

terminals. Marconi's use of the word antenna (Italian for pole) would

become a popular term for what today is uniformly known as the

antenna.

Smart Antennas Today

Today, smart antennas have been widely deployed in many of the top

wireless networks worldwide to address wireless network capacity and

performance challenges.

Several different versions of smart antennas are either in development or

available on the market today. Appliqué smart antenna systems can be

added to existing cell sites, enabling software-controlled pattern changes

or software-optimized antenna patterns that have produced capacity

increases of up to 35-94% in some deployments. Appliqué smart antenna

systems provide greater flexibility in controlling and customizing sector

antenna pattern beamwidth and azimuthal orientation over that of

standard sector antennas.

A second approach, embedded smart antennas, uses adaptive array

processing within the channel elements of a base station. The smart

antenna processing takes place in the base station signal path, using a

custom, narrow beam to track each mobile in the network. Embedded

smart antenna system trials have been proven to deliver 2.5-3 times the

capacity of current 2-2.5G base stations.

3.3- Types of Smart Antenna

The following are distinctions between the two major categories of smart

antennas regarding the choices in transmit strategy:

1).Adaptive array - an infinite number of patterns (scenario-based) that

are adjusted in real time .

2).Switched beam - a finite number of fixed, predefined patterns or

combining strategies (sectors).

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3.3.1- Adaptive Array

Adaptive antenna technology represents the most advanced smart

antenna approach to date. Using a variety of new signal-processing

algorithms, the adaptive system takes advantage of its ability to

effectively locate and track various types of signals to dynamically

minimize interference and maximize intended signal reception.

Both systems attempt to increase gain according to the location of the

user; however, only the adaptive system provides optimal gain while

simultaneously identifying, tracking, and minimizing interfering signals.

Figure 3.3:- Adaptive Array System:- Representative Depiction of a Main Lobe

Extending Toward a User.

3.3.2- Switched Beam

Switched beam antenna systems form multiple fixed beams with

heightened sensitivity in particular directions. These antenna systems

detect signal strength, choose from 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 metallic properties and physical design of a single element (like a

sectorized antenna), switched beam systems combine the outputs of

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multiple antennas in such a way as to form finely sectorized (directional)

beams with more spatial selectivity than can be achieved with

conventional, single-element approaches.

Figure 3.4:-Switched Beam System

3.4- Relative Benefits of Switched Beam and Adaptive Array

Systems

Integration

Switched beam systems are traditionally designed to retrofit widely

deployed cellular systems. It has been commonly implemented as an add-

on or appliqué technology that intelligently addresses the needs of

mature networks

Range/coverage

Switched beam systems can increase base station range from 20 to 200

percent over conventional sectored cells, depending on environmental

circumstances and the hardware/software used. The added coverage can

save an operator substantial infrastructure costs and means lower prices

for consumers. Also, the dynamic switching from beam to beam

conserves capacity because the system does not send all signals in all

directions. In comparison, adaptive array systems can cover a broader,

more uniform area with the same power levels as a switched beam

system.

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Interference suppression

Switched beam antennas suppress interference arriving from directions

away from the active beam's center. Because beam patterns are fixed,

however, actual interference rejection is often the gain of the selected

communication beam pattern in the interferer's direction. Also, they are

normally used only for reception because of the system's ambiguous

perception of the location of the received signal (the consequences of

transmitting in the wrong beam being obvious). Also, because their

beams are predetermined, sensitivity can occasionally vary as the user

moves through the sector.

Adaptive array technology currently offers more comprehensive

interference rejection. Also, because it transmits an infinite, rather than

finite, number of combinations, its narrower focus creates less

interference to neighboring users than a switched-beam approach.

3.5-Working of Smart Antenna

Traditional switched beam and adaptive array systems enable a base

station to customize the beams they generate for each remote user

effectively by means of internal feedback control. Generally speaking,

each approach forms a main lobe toward individual users and attempts

to reject interference or noise from outside of the main lobe.

Listening to the Cell (Uplink Processing)

It is assumed here that a smart antenna is only employed at the base

station and not at the handset or subscriber unit. Such remote radio

terminals transmit using omnidirectional antennas, leaving it to the base

station to separate the desired signals from interference selectively.

Typically, the received signal from the spatially distributed antenna

elements is multiplied by a weight, a complex adjustment of an

amplitude and a phase. These signals are combined to yield the array

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output. An adaptive algorithm controls the weights according to

predefined objectives. For a switched beam system, this may be primarily

maximum gain; for an adaptive array system, other factors may receive

equal consideration. These dynamic calculations enable the system to

change its radiation pattern for optimized signal reception.

Speaking to the Users (Downlink Processing) The task of transmitting in a spatially selective manner is the major

basis for differentiating between switched beam and adaptive array

systems. As described below, switched beam systems communicate with

users by changing between preset directional patterns, largely on the

basis of signal strength. In comparison, adaptive arrays attempt to

understand the RF environment more comprehensively and transmit

more selectively.

The type of downlink processing used depends on whether the

communication system uses time division duplex (TDD), which transmits

and receives on the same frequency (e.g., PHS and DECT) or frequency

division duplex (FDD), which uses separate frequencies for transmit and

receiving (e.g., GSM). In most FDD systems, the uplink and downlink

fading and other propagation characteristics

may be considered independent, whereas in TDD systems the uplink and

downlink channels can be considered reciprocal. Hence, in TDD systems

uplink channel information may be used to achieve spatially selective

transmission. In FDD systems, the uplink channel information cannot be

used directly and other types of downlink processing must be considered.

3.6- Categories of Smart Antenna

A smart antenna is a digital wireless communications antenna system

that takes advantage of diversity effect at the source (transmitter), the

destination (receiver), or both. Diversity effect involves the transmission

and/or reception of multiple radio frequency (RF) waves to increase data

speed and reduce the error rate.

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In conventional wireless communications, 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 vulnerable to

problems caused by multipath effects. When an electromagnetic field (EM

field) is met with obstructions such as hills, canyons, buildings, and

utility wires, the wavefronts are scattered, and thus they take many

paths to reach the destination. The late arrival of scattered portions of

the signal causes problems such as fading, cut-out (cliff effect), and

intermittent reception (picket fencing). In a digital communications

system like the Internet, it can cause a reduction in data speed and an

increase in the number of errors. The use of smart antennas can reduce

or eliminate the trouble caused by multipath wave propagation.

Smart antennas fall into three major categories:--

1). SIMO (single input, multiple output)

2). MISO (multiple input, single output)

3). MIMO (multiple input, multiple output).

SIMO

SIMO (single input, multiple output) is an antenna technology for

wireless communications in which multiple antennas are used at the

destination (receiver). The antennas are combined to minimize errors and

optimize data speed. The source (transmitter) has only one antenna.

SIMO is one of several forms of smart antenna technology, the others

being MIMO (multiple input, multiple output) and MISO (multiple input,

single output).

In digital communications systems such as wireless Internet, it can

cause a reduction in data speed and an increase in the number of errors.

The use of two or more antennas at the destination can reduce the

trouble caused by multipath wave propagation.

SIMO technology has widespread applications in digital television (DTV),

wireless local area networks (WLANs), metropolitan area networks

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(MANs), and mobile communications. An early form of SIMO, known as

diversity reception, has been used by military, commercial, amateur, and

shortwave radio operators at frequencies below 30 MHz since the First

World War.

MISO

MISO (multiple input, single output) is an antenna technology for

wireless communications in which multiple antennas are used at the

source (transmitter). The antennas are combined to minimize errors and

optimize data speed. The destination (receiver) has only one antenna.

MISO is one of several forms of smart antenna technology, the others

being MIMO (multiple input, multiple output) and SIMO (single input,

multiple output).

In digital communications systems such as wireless Internet, it can

cause a reduction in data speed and an increase in the number of errors.

The use of two or more antennas, along with the transmission of multiple

signals (one for each antenna) at the source, can reduce the trouble

caused by multipath wave propagation.

MISO technology has widespread applications in digital television (DTV),

wireless local area networks (WLANs), metropolitan area networks

(MANs), and mobile communications.

MIMO

MIMO (multiple input, multiple output) is an antenna technology for

wireless communications in which multiple antennas are used at both

the source (transmitter) and the destination (receiver). The antennas at

each end of the communications circuit are combined to minimize errors

and optimize data speed. MIMO is one of several forms of smart antenna

technology, the others being MISO (multiple input, single output) and

SIMO (single input, multiple output).

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In digital communications systems such as wireless Internet, it can

cause a reduction in data speed and an increase in the number of errors.

The use of two or more antennas, along with the transmission of multiple

signals (one for each antenna) at the source and the destination,

eliminates the trouble caused by multipath wave propagation, and can

even take advantage of this effect.

MIMO technology has aroused interest because of its possible

applications in digital television (DTV), wireless local area networks

(WLANs), metropolitan area networks (MANs), and mobile

communications.

3.7- Function of Smart Antenna

Smart antennas (also known as adaptive array antennas, multiple

antennas and recently MIMO) are antenna arrays with smart signal

processing algorithms used to identify spatial signal signature such as

the direction of arrival (DOA) of the signal, and use it to calculate

beamforming vectors, to track and locate the antenna beam on the

mobile/target.

Smart antennas have two main functions: DOA estimation and

Beamforming.

3.7.1- Beamforming

Beamforming is a signal processing technique used with arrays of

transmitting or receiving transducers that control the directionality of, or

sensitivity to, a radiation pattern. When receiving a signal, beamforming

can increase the receiver sensitivity in the direction of wanted signals

and decrease the sensitivity in the direction of interference and noise.

When transmitting a signal, beamforming can increase the power in the

direction the signal is to be sent. The change compared with an

omnidirectional receiving pattern is known as the receive gain (or loss).

The change compared with an omnidirectional transmission is known as

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the transmission gain. These changes are done by creating beams and

nulls in the radiation pattern. In electronics, gain is usually taken as

the mean ratio of the signal output of a system to the signal input of the

system.

Beamforming can be done with either radio or sound waves, and can also

be thought of as spatial filtering. As an everyday analogy, the human

brain uses a form of signal processing on its two sound transducers

(ears) and determines where the sound came from (sound localization). In

the comparable beamforming analogy, digital computers use signal

processing on an array of two (or generally more) electromagnetic sound

transducers (microphones) to determine the direction of maximum signal

strength, and thus the likely origin of the sound. A microphone with a

cord A microphone, sometimes called a mic (pronounced mike), is a

device that converts sound into an electrical signal. In

telecommunications, and particularly in radio, signal strength is the

measure of how strongly a transmitted signal is being received,

measured, or predicted, at a reference point that is a significant distance

from the transmitting antenna.

Beamforming takes advantage of interference to change the directionality

of the array. When transmitting, a beamformer controls the phase and

relative amplitude of the signal at each transmitter, in order to create a

pattern of constructive and destructive interference in the wavefront.

When receiving, information from different sensors is combined in such a

way that the expected pattern of radiation is preferentially observed.

Interference of two circular waves - Wavelength (decreasing bottom to

top) and Wave centers distance (increasing to the right).

In the receive beamfomer the signal from each antenna may be amplified

by a different "weight." Different weighting patterns (eg Dolph-Chebyshev)

can be used to achieve the desired sensitivity patterns. . A main lobe is

produced together with nulls and sidelobes. As well as controlling the

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main lobe width (the beam) and the sidelobe levels, the position of a null

can be controlled. This is useful to ignore noise or jammers in one

particular direction, while listening for events in other directions. A

similar result can be obtained on transmission. Jammer can refer to: A

device used in electronic warfare to inhibit or halt the transmission of

signals.

Figure3.5:- BeamForming Lobe.

Figure3.6:- Figure show pattern of Beamforming

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Beamforming techniques can be broadly divided into two categories:

A).Conventional (fixed) beamformers or switched beam smart

antennas.

B).Adaptive beamformers or adaptive array smart antennas

Conventional beamformers use a fixed set of weightings and time-delays

(or phasing’s) to combine the signals from the sensors in the array,

primarily using only information about the location of the sensors in

space and the wave directions of interest. In contrast, adaptive

beamforming techniques, generally combine this information with

properties of the signals actually received by the array, typically to

improve rejection of unwanted signals from other directions. This process

may be carried out in the time or frequency domains. Smart Antenna

refers to a system of antenna arrays with smart signal processing

algorithms that are used to identify the direction of arrival (DOA) of the

signal, and use it to calculate beamforming vectors, to track and locate

the antenna beam on the mobile/target. ... Smart Antenna refers to a

system of antenna arrays with smart signal processing algorithms that

are used to identify the direction of arrival (DOA) of the signal, and use it

to calculate beamforming vectors, to track and locate the antenna beam

on the mobile/target. ...

As the name indicates, an adaptive beamformer is able to adapt

automatically its response to different situations. Some criterion has to

be set up to allow the adaption to proceed such as minimising the total

noise output. Because of the variation of noise with frequency, in wide

band systems it may be desirable to carry out the process in the

frequency domain. An adaptive beamformer is signal processing system

often used with an array of radar antennae (or phased array) in order to

transmit or receive signals in different directions without having to

mechanically steer the array. ... Frequency domain is a term used to

describe the analysis of mathematical functions with respect to

frequency.

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3.7.2- Direction of Arrival (DOA)

Direction of Arrival (DOA) denotes the direction from which usually a

propagating wave arrives at a point, where usually a set of sensors are

located. This set of sensors forms what is called a sensor array. Often

there is the associated technique of beamforming which is estimating the

signal from a given direction. Various engineering problems addressed in

the associated literature are as follows: A wave crashing against the

shore a wave is a disturbance that propagates. Beamforming is the

process of delaying the outputs of the sensors in an arrays aperture and

adding these together, to reinforce the signal with respect to noise or

waves propagating in different directions.

Find the direction relative to the array where the underwater sound

source is located.

Directions of different sound sources around you are also located

by you using a process similar to those used by the algorithms in the

literature.

Radio telescopes use these techniques to look at a certain location

in the sky.

Recently beamforming has also been used in RF applications such

as wireless communication. Compared with the spatial diversity

techniques, beamforming is preferred in terms of complexity. On the

other hand beamforming in general has much lower data rates. In

multiple access channel (CDMA,FDMA,TDMA) beamforming is

necessary & sufficient.

The smart antenna system estimates the direction of arrival of the signal,

using any of the techniques like MUSIC (Multiple Signal Classification) or

ESPRIT (Estimation of Signal Parameters via Rotational Invariant

Techniques) algorithms,Matrix Pencil method or their derivatives. They

involve finding a spatial spectrum of the antenna/sensor array, and

calculating the DOA from the peaks of this spectrum. MUSIC involves

calculation of eigenvalues and eigenvectors of an autocorrelation matrix

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of the input vectors from the receiving antenna array. These calculations

are computationally intensive. Matrix Pencil is very efficient in case of

real time systems, and under the correlated sources. In mathematics, a

number is called an eigenvalue of a matrix if there exists a nonzero vector

such that the matrix times the vector is equal to the same vector

multiplied by the eigen value.In linear algebra, the eigenvectors (from the

German eigen meaning own) of a linear operator are non-zero vectors

which, when operated on by the operator, result in a scalar multiple of

themselves.

3.9- Application of Smart Antenna

Smart Antenna is used in number of fields. It has number of

Applications. Here are some of the fields where Smart Antenna used:-

1). MOBILE COMMUNICATION.

2).WIRELESS COMMUNICATION. 3). RADAR. 4).SONAR

APPLICATION OF SMART ANTENNAS TO MOBILE

COMMUNICATIONS SYSTEMS

Smart or adaptive antenna arrays can improve the performance of

wireless communication systems. An overview of strategies for achieving

coverage, capacity, and other improvements is presented, and relevant

literature is discussed. Multipath mitigation and direction finding

applications of arrays are briefly discussed, and potential paths of

evolution for future wireless systems are presented. Requirements and

implementation issues for smart antennas are also considered.

Smart antennas are most often realized with either switched-beam or

fully adaptive array antennas. An array consists of two or more antennas

(the elements of the array) spatially arranged and electrically

interconnected to produce a directional radiation pattern. In a phased

array the phases of the exciting currents in each element antenna of the

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array are adjusted to change the pattern of the array, typically to scan a

pattern maximum or null to a desired direction.

A smart antenna system consists of an antenna array, associated RF

hardware, and a computer controller that changes the array pattern in

response to the radio frequency environment, in order to improve the

performance of a communication or radar system.

Switched-beam antenna systems are the simplest form of smart antenna.

By selecting among several different fixed phase shifts in the array feed,

several fixed antenna patterns can be formed using the same array. The

appropriate pattern is selected for any given set of conditions. An

adaptive array controls its own pattern dynamically, using feedback to

vary the phase and/or amplitude of the exciting current at each element

to optimize the received signal.

Smart or adaptive antennas are being considered for use in wireless

communication systems. Smart antennas can increase the coverage and

capacity of a system. In multipath channels they can increase the

maximum data rate and mitigate fading due to cancellation of multipath

components. Adaptive antennas can also be used for direction finding,

with applications including emergency services and vehicular traffic

monitoring. All these enhancements have been proposed in the literature

and are discussed in this paper. In addition, possible paths of evolution,

incorporating adaptive antennas into North American cellular systems,

are presented and discussed. Finally, requirements for future adaptive

antenna systems and implementation issues that will

influence their design are outlined.

Range extension

In sparsely populated areas, extending coverage is often more important

than increasing capacity. In such areas, the gain provided by adaptive

antennas can extend the range of a cell to cover a larger area and more

users than would be possible with omnidirectional or sector antennas.

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Interference reduction and rejection

In populated areas, increasing capacity is of prime importance. Two

related strategies for increasing capacity are interference reduction on

the downlink and interference rejection on the uplink. To reduce

interference, directional beams are steered toward the mobiles.

Interference to co-channel mobiles occurs only if they are within the

narrow beamwidth of the directional beam. This reduces the probability

of co-channel interference compared with a system using omnidirectional

base station antennas.

Interference can be rejected using directional beams and/or by forming

nulls in the base station receive antenna pattern in the direction of

interfering co-channel users.

Interference reduction and rejection can allow N c (which is dictated by

co-channel interference) to be reduced, increasing the capacity of the

system.

Interference reduction can be implemented using an array with steered or

switched beams. By using directional beams to communicate with

mobiles on the downlink, a base station is less likely to interfere with

nearby co-channel base stations than if it used an omnidirectional

antenna.

There will be a small percentage of time during which co-channel

interference is strong, e.g., when a mobile is within the main beam of a

nearby co-channel base station.

This can be overcome by handing off the mobile within its current cell to

another channel that is not experiencing strong co-channel interference.

3.10- Advantages and Disadvantages of Smart

Antenna. Advantages

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Increased number of users

Due to the targeted nature of smart antennas frequencies can be reused

allowing an increased number of users. More users on the same

frequency space means that the network provider has lower operating

costs in terms of purchasing frequency space.

Increased Range

As the smart antenna focuses gain on the communicating device, the

range of operation increases. This allows the area serviced by a smart

antenna to increase. This can provide a cost saving to network providers

as they will not require as many antennas/base stations to provide

coverage.

Geographic Information

As smart antennas use ‘targeted’ signals the direction in which the

antenna is transmitting and the gain required to communicate with a

device can be used to determine the location of a device relatively

accurately. This allows network providers to offer new services to devices.

Some services include, guiding emergency services to your location,

location based games and locality information.

Security

Smart antennas naturally provide increased security, as the signals are

not radiated in all directions as in a traditional omni-directional antenna.

This means that if someone wished to intercept transmissions they would

need to be at the same location or between the two communicating

devices.

Reduced Interference

Interference which is usually caused by transmissions which radiate in

all directions are less likely to occur due to the directionality introduced

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by the smart antenna. This aids both the ability to reuse frequencies and

achieve greater range.

Increased bandwidth

The bandwidth available increases form the reuse of frequencies and also

in adaptive arrays as they can utilize the many paths which a signal may

follow to reach a device.

Easily integrated

Smart antennas are not a new protocol or standard so the antennas can

be easily implemented with existing non smart antennas and devices.

Disadvantages

Complex

A disadvantage of smart antennas is that they are far more complicated

than traditional antennas. This means that faults or problems may be

harder to diagnose and more likely to occur.

More Expensive

As smart antennas are extremely complex, utilizing the latest in

processing technology they are far more expensive than traditional

antennas. However this cost must be weighed against the cost of

frequency space.

Larger Size

Due to the antenna arrays which are utilized by smart antenna systems,

they are much larger in size than traditional systems. This can be a

problem in a social context as antennas can be seen as ugly or unsightly.

Dept. of E&C PESIT-BSC

Location

The location of smart antennas needs to be considered for optimal

operation. Due to the directional beam that ‘swings’ from a smart

antenna locations which are optimal for a traditional antenna are not for

a smart antenna. For example in a road context, smart antennas are

better situated away from the road, unlike normal antennas which are

best situated along the road.

3.11- Features and Benefit of Smart Antenna

Feature of Smart Antenna

1).Signal gain - Inputs from multiple antennas are combined to optimize

available power required to establish given level of coverage.

2).Interference Rejection - Antenna pattern can be generated toward

co-channel interference sources, improving the signal-to-interference

ratio of the received signals.

3).Spatial diversity-Composite information from the array is used to

minimize fading and other undesirable effects of multipath propagation.

4).Power efficiency- Combines the inputs to multiple elements to

optimize available processing gain in the downlink (toward the user)

Benefit of Smart Antenna

1).Better range/coverage- Focusing the energy sent out into the cell

increases base station range and coverage. Lower power requirements

also enable a greater battery life and smaller/lighter handset size.

2).Increased capacity- Precise control of signal nulls quality and

mitigation of interference combine to frequency reuse reduce distance (or

cluster size),improving capacity. Certain adaptive technologies (such as

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space division multiple access) support the reuse of frequencies within

the same cell.

3).Multipath rejection- Can reduce the effective delay spread of the

channel, allowing higher bit rates to be supported without the use of an

equalizer.

4).Reduced expense- Lower amplifier costs, power consumption, and

higher reliability will result.

4. Conclusion

This report aims to explain the basic concept of Smart Antenna and some of its Application.

First Question arises what is Smart Antenna?

A smart antenna combines an antenna array with a digital signal-

processing capability to transmit and receive in an adaptive, spatially sensitive manner. Or In other words Smart Antenna is an Array of antenna which is used to optimize its reception and transmit pattern.

There are two types of Smart Antenna:-

1). Switched Beam- Switched beam antenna systems form multiple fixed beams with heightened sensitivity in particular directions. These antenna systems detect signal strength, choose from one of several

predetermined, fixed beams, and switch from one beam to another as the mobile moves throughout the sector.

2). Adaptive Array- Adaptive antenna technology represents the most

advanced smart antenna approach to date. the adaptive system takes advantage of its ability to effectively locate and track various types of signals to dynamically minimize interference and maximize intended

signal reception.

Both systems attempt to increase gain according to the location of the user; however, only the adaptive system provides optimal gain while

simultaneously identifying, tracking, and minimizing interfering signals.

Smart antenna works in two processes. First one is Uplinking and second one is Downlinking

There are 2 categories of Smart Antenna:-

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1). SIMO (Single Input Multiple Output)

2). MISO (Multiple Input Single Output)

3).MIMO (Multiple Input Multiple Output)

Basically Smart antenna has two functions :-

1).Beamforming-

2).Direction of Arrival

Smart antenna is used in various fields the most important is named below:-

1). Mobile Communication

2). Wireless Communication

3). RADAR

4).SONAR

There are some of the factors which affects the performance of Smart

Antenna . These factors reduce the Quality of Smart Antenna.Factors are:-

1).Resonant Frequency

2).Gain

3).Impedance

4).Bandwidth

5).Polarization

6).Transmission and Reception

Merits of Smart Antenna

1). Increased number of users.

2). Increased Range

3). Security

4). Reduced Interference.

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Demerits of Smart Antenna:-

1). Complex

2). Expensive

3). Large Size

4). Location

References

1). www.wikipedia.com

2). www.statemaster.com

3). www.iec.org

4). http://www.iec.org/online/tutorials/smart_ant/

5).W. L. Stutzman and G. A. Thiele, Antenna theory and

Design, John Wiley & Sons, New York, 1981.

6). D. Johnson and D. Dudgeon, Array Signal Processing,

Prentice-

Hall, Englewood Cli_s, NJ, 1993

7). http://www.smartanteenas.googlepages.com

8). Michael Chryssomallis “Smart antennas” IEEE antenna and

propagation magazine” Vol 42 No 3 pp 129-138, June 2000.

9). D. Johnson and D. Dudgeon, Array Signal Processing,

Prentice-

Hall, Englewood Cli_s, NJ, 1993

10). Special issue on blind identi_cation and estimation," IEEE

Proceedings, mid-1998.

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11). R Kronberger,H Lindermerier,J Hopf “Smart antenna

applications on vehicles with low profile array antenna” Proc

IEEE Vol 53 pp1-3 September 2003.