Smart Antenna Report for third year Electronics and Communication Students . Smart Antenna is a really nice topic to discover and present for third year students of electronics and communication engineering branch. So this Report covers it all .

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SMART ANTENNA TECHNOLOGY
CHAPTER-1
INTRODUCTION
A smart antenna commonly known as multiple antenna or adaptive array antenna can be defined as a
digital wireless communications system with increased efficiency. This type of antenna works by using
a diversity effect at the wireless system’s transceiver. These are the antenna arrays having smart signal
processing algorithms that are used for identification of the spatial signal signature. The major
applications of the smart antennas can be found notably in radio astronomy, radio telescopes, cellular
systems, acoustic signal processing, scan radar and much more.
Interest in Smart Antenna Technology for wireless communication systems is increasing in recent
years. Considerable amount of research and fields trials is being conducted to improve the
performance of the system in terms of increasing the capacity and range.
A smart antenna consists of several antenna elements, whose signal is processed adaptively in order to
exploit the spatial domain of the mobile radio channel. The smart antenna technology can significantly
improve wireless system performance and economics for a range of potential users. It enables
operators of PC's cellular and wireless local loop networks to realize significant increase in signal
quality, network capacity and coverage.
In actual, antennas are not Smart Antenna, systems are smart. Generally collocated with a base station,
a smart antenna system combines an antenna array with a digital signal-processing capability to
transmit and receive in an adaptive, spatially sensitive manner. In other words, such a system can
automatically change the directionality of its radiation patterns in response to its signal environment.
This can dramatically increase the performance characteristics (such as capacity) of a wireless system.
This is a new and promising technology in the field of wireless and mobile communications in which
capacity and performance are usually limited by two major impairments multipath and co-channel
interference. Multipath is a condition that arises when a transmitted signal undergoes reflection from
various obstacles in the environment. This gives rise to multiple signals arriving from different
directions at the receiver. Smart antennas are antenna arrays with smart signal processing algorithms to
identify spatial signal signature such as the Direction of arrival (DOA) of the signal and use it to
calculate beam forming vectors, to track and locate the antenna beam on the mobile targets. The
antenna could optionally be any sensor. Smart antenna techniques are used notably in Acoustic Signal
Processing, Track and Scan Radar, Radio Astronomy and Radio Telescopes and mostly in
Cellular Systems like W-CDMA and UMTS.

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CHAPTER-2
ABSTRACT
Wireless systems are undoubtedly an essential part of modern society and are becoming more so as we
move towards the “information society” and demand access to more information, more immediately
and in more places. Concurrently, technological developments are making new applications possible,
opening up new markets, and promising significant economic benefits. It is, therefore, increasingly
important to improve the efficiency with which use is made of the spectrum. The next generation
mobile telephone system may require an order of magnitude increase in capacity. Since present day
systems are close to the Shannon limit, there is relatively little to be gained by improving the
modulation and coding schemes, and smart antennas have been identified as one technique that may
close the predicted performance gap.
In general, the term “Smart Antenna” may be used to describe any antenna system that incorporates
some degree of adaptation to the RF environment to improve performance. There are a number of
alternative approaches to incorporating this adaptation. These include methods that are based on beam
space, signal space, space-time processing and space-time detection method.
It should be noted that a distinction is made between those “smart” systems that achieve improved
performance using diversity methods, for example diversity combining and MIMO, and those that
adapt weighted excitations to the elements of the antenna to optimize its pattern performance. Simple
diversity systems are used widely, and the incorporation of MIMO techniques is rising rapidly, in
advance of a formal specification. This project hence concentrated on the weight adaptation
techniques, which are further from widespread adoption, but which may offer additional or
complementary benefits to the diversity methods.

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CHAPTER-3
TYPES of SMART ANTENNA
Two of the main types of smart antennas include switched beam smart antennas and adaptive array
smart antennas. Switched beam systems have several available fixed beam patterns. A decision is
made as to which beam to access, at any given point of time, based upon the requirements of the
system. Adaptive arrays allow the antenna to steer the beam to any direction of interest while
simultaneously nullifying interfering signals. Beam direction can be estimated using the Direction-of-
Arrival (DOA) estimation methods.
Fig.1. Classification of Smart Antenna
There are two major types of smart antennas explained below:
3.1 Switched Beam Smart Antennas
A smart antenna that has many fixed beam patterns is known as switched beam antennas. While using
this type of smart antennas, there is a need to make a decision on which beam should be accessed that
depends upon the needs of the system. The major advantage of this kind of smart antennas is that it is
easy to implement in the present cell structures and cost very less.
3.2 Adaptive Array Smart Antennas
The antennas which are allowed to steer the beam in any direction along with nulling the interfering
signals are known as adaptive array smart antennas. The direction of arrival estimation methods
(DOA) is used to estimate the beam direction. It is the best type of smart antennas and has a complex
transceiver.

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3.3 Comparison between Switched Beam and Adaptive Array Systems
Fig.2. Types of Smart Antenna
Switched Beam System
 It uses multiple fixed directional beams with narrow beam widths.
 They do not require complex algorithms; simple algorithms are used for beam selection.
 It requires only moderate interaction between mobile unit and base station as compared to
adaptive array system.
 Since low technology is used, it has lesser cost and complexity.
 Integration into existing cellular system is easy and cheap.
 It provides significant increase in coverage and capacity compared to conventional antenna
based systems.
 It cannot distinguish between direct signal and interfering and/or multipath signals, this leads
to undesired enhancement of the interfering signal more than the desired signal.
 Since, there is no null steering involved, switched beam systems offer limited co-channel
interference suppression as compared to the adaptive array systems.

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Adaptive Array System
 A complete adaptive system; steers the beam towards desired signal of interest and places nulls
at the interfering signal directions.
 It requires complicated adaptive algorithms to steer the beam and the nulls.
 It has better interference rejection capability compared to Switched beam systems.
 It is not easy to implement in existing systems i.e. up-gradation is difficult and expensive.
 Since, continuous steering of the beam is required as the mobile moves; high interaction
between mobile unit and base station is required.
 Since, the beam continuously follows the user; intra-cell hand-offs are less.
 It provides better coverage and increased capacity because of improved interference rejection
as compared to the Switched beam systems.
 It can either reject multipath components or add them by correcting the delays to enhance.

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CHAPTER-4
THE ARCHITECTURE OF SMART ANTENNA SYSTEMS
Fig.3. Architecture of Smart Antenna
How Do Smart Antenna Systems Work?
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 Omni -directional 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 amplitude and a phase. These signals are combined to yield the array 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.

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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 use 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 to transmit and receive the signal (e.g. GSM). 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.
Interference Limited Systems.
Unfortunately, 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. In particular,
when omnidirectional antennas are used at the base station, the transmission/reception of each user's
signal becomes a source of interference to other users located in the same cell, making the overall
system interference limited. An effective way to reduce this type of interference is to split up the cell
into multiple sectors and use directional antennas. Ultra Adaptive Beam forming Implementation The
high-performance digital signal processing (DSP) blocks, embedded processors and Logic Elements
(LEs) make them ideal for adaptive beam forming applications. In addition, the inclusion of the dual
core processor with the NEON acceleration unit can be used for beam forming adaptations. The signal
from each receive antenna is first down converted to baseband, processed by the matched filter-
multipath estimator and accordingly assigned to different rake fingers. The beam forming unit on each
rake finger then calculates the corresponding beam former weights and channel estimate using the
pilot symbols that have been transmitted through the Dedicated Physical Data Channel (DPDCH). The
QRD-based Recursive Least squares (RLS) algorithm is selected as the weight update algorithm for its
fast convergence and good numerical properties. The updated beam former weights are then used for
multiplication with the data that has been transmitted through the DPDCH. Maximal Ratio Combining
(MRC) of the signals from all fingers is then performed to yield the final soft estimate of the DPDCH
data.

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CHAPTER-5
BASIC WORKING MECHANISM
Fig.4.Basic Working System
Direction of arrival (DOA) estimation
The smart antenna system estimates the direction of arrival of the signal, using techniques such as
MUSIC (Multiple Signal Classification), estimation of signal parameters via rotational invariance
techniques (ESPRIT) algorithms, Matrix Pencil method or one of their derivatives. They involve
finding a spatial spectrum of the antenna/sensor array, and calculating the DOA from the peaks of this
spectrum. These calculations are computationally intensive. Matrix Pencil is very efficient in case of
real time systems, and under the correlated sources.
Beam forming
Beam forming is the method used to create the radiation pattern of the antenna array by adding
constructively the phases of the signals in the direction of the targets/mobiles desired, and nulling the
pattern of the targets/mobiles that are undesired/interfering targets. This can be done with a simple
Finite Impulse Response (FIR) tapped delay line filter. The weights of the FIR filter may also be
changed adaptively, and used to provide optimal beam forming, in the sense that it reduces the
Minimum Mean Square Error between the desired and actual beam pattern formed. Typical algorithms
are the steepest descent, and Least Mean Squares algorithms. In digital antenna arrays with multi
channels use the digital beam forming, usually by DFT or FFT.

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Fig.5.Beamforming Pattern
Advantage of Beam Forming.
There are following advantages of Beam forming:-
 Processing Speed
 Flexibility
 Lower Risk.
 Cost Reduction Path.
Phase cancellation
When waves of two multipath signals are rotated to exactly 180° out of phases, the signals will cancel
each other. While this sounds severe, it is rarely sustained on any given call (and most air interface
standards are quite resilient to phase cancellation). In other words, a call can be maintained for a
certain period of time while there is no signal, although with very poor quality. The effect is of more
concern when the control channel signal is canceled out, resulting in a black hole, a service area in
which call set-ups will occasionally fail.

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CHAPTER-6
FUNCTIONS OF SMART ANTENNA
A smart antenna system can perform the following functions:-
First, the direction of arrival of all the incoming signals including the interfering signals and the
multipath signals are estimated using the Direction of Arrival algorithms.
Secondly, the desired user signal is identified and separated from the rest of the unwanted incoming
signals.
Lastly, a beam is steered in the direction of the desired signal and the user is tracked as he moves while
placing nulls at interfering signal directions by constantly updating the complex weights.
As discussed previously, it is quite evident that the direction of radiation of the main beam in an array
depends upon the phase difference between the elements of the array. Therefore, it is possible to
continuously steer the main beam in any direction by adjusting the progressive phase difference
between the elements. The same concept forms the basis in adaptive array systems in which the phase
is adjusted to achieve maximum radiation in the desired direction.
For accurate performance, they are required to provide accurate translation of the RF signal from the
analog to the digital domain. The digital signal processor forms the heart of the system which accepts
the IF signal in digital format and the processing of the digital data is driven by software. The
processor interprets the incoming data information which determines the complex weights
(amplification and phase information) and multiplies the weights to each element output to optimize
the array pattern. The optimization is based on particular criteria which minimizes the contribution
from noise and interference while producing maximum beam gain at the desired direction. There are
several algorithms based on different criteria for updating and computing the optimum weights.

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CHAPTER-7
ADVANTAGES AND DISADVANTAGES
6.1 Advantages
There are many advantages offered by the smart antennas and some of them are stated below:
 Reduction in Co-Channel Interference.
Smart antennas have a property of spatial filtering to focus radiated energy in the form of narrow
beams only in the direction of the desired mobile user and no other direction. In addition, they also
have nulls in their radiation pattern in the direction of other mobile users in the vicinity. Therefore,
there is often negligible co-channel interference. There is a very reduced chance of interference due to
the transmissions that radiate in all the directions. The smart antennas come with directionality that has
the ability to achieve greater range and reuse frequencies.
 Range Improvement.
Since, smart antennas employs collection of individual elements in the form of an array they give rise
to narrow beam with increased gain when compared to conventional antennas using the same power.
The increase in gain leads to increase in range and the coverage of the system. Therefore, fewer base
stations are required to cover a given area.
 Increase in Capacity.
Smart antennas enable reduction in co-channel interference which leads to increase in the frequency
reuse factor means smart antennas allow more users to use the same frequency spectrum at the same
time bringing about tremendous increase in capacity.
 Reduction in Transmitted Power.
Ordinary antennas radiate energy in all directions leading to a waste of power. Comparatively, smart
antennas radiate energy only in the desired direction. Therefore, less power is required for radiation at
the base station. Reduction in transmitted power also implies reduction in interference towards other
users.
 Reduction in Handoff.
To improve the capacity in a crowded cellular network, congested cells are further broken into micro
cells to enable increase in the frequency reuse factor. This results in frequent handoffs as the cell size
is smaller. Using smart antennas at the base station, there is no need to split the cells as the capacity is
increased by using independent spot beams.

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 Increasing number of users.
The frequencies of smart antennas can be used gain because of their targeted nature that allows an
increased number of users. It means there will be a lower operating cost for the network provider in
terms of shopping frequency space.
6.2 Disadvantages
 Complexity
The biggest disadvantage that comes with the smart antennas is that they have high complexity when
compared to the traditional antennas. It makes it difficult to diagnose the faults or problems. A smart
antenna transceiver is much more complex than a traditional base station transceiver. Need for more
powerful algorithms, processors and control systems.
 High Cost
The smart antennas have high complexity and it utilizes the latest to process the expensive technology
that makes it extremely costly. New demands on network functions such as resource and mobility
management are needed.
 Bigger Size
The smart antennas have a much bigger size than the traditional ones because of the antenna arrays. It
can be a problem in a social way. For the smart antenna to obtain a reasonable gain, an array antenna
with several elements is necessary.

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CHAPTER-8
TECHNOLOGICAL DEVELOPEMENT
In this Section we present the outcome of the work undertaken under the Technology Development
activity. The motivation has been to demonstrate how the use of novel materials could benefit the
performance of a wireless system. The selected application was the development of a low-profile
(quasiplanar) structure that would produce a monopole type pattern, i.e. a conical type of radiation
pattern with a null at foresight. This would find application in, for example, WLAN systems, as the
base station antenna located centrally in the ceiling of an open plan office.
The research has been initiated from, in particular, work by F. Yang et al. In their work the authors
proposed a met material surface wave antenna, consisting of a dipole in close proximity to an array
printed on a grounded dielectric substrate. In their approach, they assumed the structure to operate as a
surface wave antenna that radiates from the edges of the PCB board. For the specified band, this
approach would reduce the profile of a standard monopole by about 90%.
In this present work package the structure was analyzed both theoretically and empirically. The
theoretical investigation of the infinite structure concluded that a prominent radiation mechanism of
this antenna is the TM leaky wave mode. A series of full wave simulations of the finite structure
including the feeding were carried out to understand how the various parameters of the antenna affect
the performance. This led to a final array configuration, which was fabricated in two differing overall
dimensions; the small and large array prototypes.
The results demonstrated that the low profile antenna design was capable of producing radiation
patterns with the desired characteristics, in terms of impedance match and pattern shape. Compared
with conventional antennas of a similar profile, the pattern modification provides a gain enhancement
of approximately 10dB in regions where users were more distant. Compared with a conventional
antenna of similar pattern performance, the profile was reduced by a factor of about 10. Such a
reduction would allow this type of antenna to be integrated into near planar structures.
Clearly, this is only one example aspect of the use to which novel materials may be put in the design of
antenna and microwave components. It has demonstrated that the properties required for the materials
may be realized, and that the expected effect on the device operation can be achieved.

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CHAPTER-9
EXTENSION OF SMART ANTENNA
A simple antenna works for a simple RF environment. Their smarts reside in their digital signal-
processing facilities. In adaptive antenna systems, this fundamental signal-processing capability is
augmented by advanced techniques that are applied to control operation in the presence of complicated
combinations of operating conditions.
The broadcasting nature of the wireless channel can be changed by the smart antennas and that’s why
they have so popular these days. It consists of the diversity effect on the transmitter, the receiver or
both. This effect includes the transmission of several radio frequencies for raising the data speed and
reducing the rate of error.
Smart antenna systems are also a defining characteristic of MIMO systems. Conventionally, a smart
antenna is a unit of a wireless communication system and performs spatial signal processing with
multiple antennas. Multiple antennas can be used at either the transmitter or receiver. Recently, the
technology has been extended to use the multiple antennas at both the transmitter and receiver; such a
system is called a multiple-input multiple-output (MIMO) system.
As extended Smart Antenna technology, MIMO supports spatial information processing, in the sense
that conventional research on Smart Antennas has focused on how to provide a digital beam forming
advantage by the use of spatial signal processing in wireless channels. Spatial information processing
includes spatial information coding such as Spatial multiplexing and Diversity Coding, as well as
beam forming.
Fig.6. MIMO Technology

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Smart Antennas have been tested in a variety of field locations with promising results. The new
antenna has demonstrated a considerable advantage over various indoor antennas with no
amplification and the set-top UHF loop/VHF rod antenna combination with built-in amplification. In a
few locations, Smart Antennas may be unable to automatically optimize the signal. A simple antenna
works for a simple RF environment. Smart antenna solutions are required as the number of users,
interference and propagation complexity grows. Their smartness resides in their digital signal
processing facilities. Like most modern advances in electronics today, the digital format for
manipulating the RF data offers numerous advantages in terms of accuracy and flexibility of operation.
Speech starts and ends as analog information. Along the way, however, Smart Antenna systems
capture, convert and modulate analog signals for transmission as digital signals and reconvert them to
analog information on the other end. In adaptive antenna systems, this fundamental signal -processing
capability is augmented by advanced techniques (algorithms) that are applied to control operation in
the presence of complicated combinations of operating conditions.

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CHAPTER-10
ADOPTION ISSUES
The results of the simulation and demonstration performed under this project indicate that significant
benefits could be derived from the use of adaptive smart antennas. However, as has been noted,
adoption is far from widespread.
With the explosion in RF applications and devices over the past decade, the required RF components
have already undergone extensive development; the challenge here is in packaging and in cost
reduction for specific applications, particularly those, such as WLAN, aimed at cost conscious
consumers.
Hardware incorporating other smart antenna techniques is, or has been, also available for both BWA
and WLAN. However, with few exceptions, these products have struggled to be successful
commercially. The apparent failure of the technology may be due, at least in part, to the slower than
expected growth in the BWA market, possibly caused by the ubiquitous availability of wired access at
a competitive price. There are now indications that the BWA market is becoming more enthusiastic,
and the adoption of smart antennas may assist this in due course by lowering both rollout and
operating costs.
In WLAN, the complementary approach of MIMO has become popular over the past 18 months, with
the launch of a number of products. Although a full standard has yet to be ratified, MIMO is serving its
users well in the 2.4GHz band, offering several times the data rate of the 802.11g standard. 2.4GHz
WLAN in the office or home location is an ideal application for MIMO, with its rich multipath, and
the adaptive antenna has perhaps little to offer over MIMO. This all indicate that adaptive smart
antennas have a role to play in improving system performance, offering this benefit at a cost effective
price. As far as hardware is concerned, and given buoyancy in the target markets, new adaptive
antenna products could be available relatively rapidly, requiring only product, not technology,
developments; a conservative estimate, based on existing product life cycles, of time to market would
be 12-18 months. However, the regulatory environment also needs to be considered.
With the exception of diversity type systems, a smart antenna generally improves performance by
shaping the antenna pattern, either explicitly, as in the case of beam steering, or as a consequence of
antenna element weight adaptation. To gain maximum advantage from the adaptive system, such
antennas would be used for both receive and transmit. This can result in increased antenna gain, and
potentially an increased effective isotropic radiated power (EIRP). In order to take full advantage of
smart antennas it may be necessary to modify the regulatory requirements to allow for this higher
EIRP. The main impact of this is upon the geographical definition of licenses, such as those required to
meet internationally agreed emission levels or UK licenses designed to share the same frequencies on
a geographical basis.

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CHAPTER-12
SUMMARY
Summarizing, we have seen how smart antennas reduce fading and suppress interference. This in turn
allows the increase in capacity of existing or future mobile communications networks. The used
algorithms for weight determination can be divided into spatial reference, temporal reference and blind
algorithms. The first use knowledge about the geometry of the antenna array, the second use a training
sequence and the last employ knowledge about the structural and statistical properties of the
transmitted signal. Future developments will include MIMO systems, which promise huge
transmission capacities. Finally let us note that for the design and simulation of any smart antenna
system, knowledge of the spatially resolved mobile radio channel is essential.
This project set out to investigate the use of adaptive smart antennas in wireless systems. The course of
the work has identified applications likely to benefit from early adoption of the technology.
Alternatively, the performance improvement would offset the high propagation loss through walls that
is experienced in the 5GHz band - this loss is typically 10-12dB, compared with less that 3dB in the
802.11b/g band. This would provide the user with the capability that can be achieved in the lower
band, but without the congestion often experienced there, and help to encourage migration into the
presently underutilized 5GHz band.
The benefits to be considerable, including:
•Increase in cell range of 40-70%.
•Reduction in spectrum required 60-70%.
•Reduction in network cost by up to 50% - resulting in a reduction in total business costs of up to one
third.
However, this is an area where the market conditions, up to now, have slowed uptake; there are
indications that this will change in the future.

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REFERENCES
[1] F. Yang and Y. Rahmat-Samii, “Microstrip Antennas Integrated With Electromagnetic Band-
Gap (EBG) Structures: A Low Mutual Coupling Design for Array Applications”, IEEE
Transactions on Antennas and Propagation, Vol. 51, No. 10, pp. 2936-3946, Oct. 2003.
[2] Z. Iluz, R. Shavit, and R. Bauer, “Microstrip Antenna Phased Array with Electromagnetic Band
gap Substrate,” IEEE Transactions on Antennas and Propagation, Vol. 52, No. 6, pp. 1446-1453,
Jun. 2004.
[3] http://www.vectorfields.co.uk
[4]Smart Antenna Systems Tutorial, The International Engineering
Consortium,http://www.iec.org/online/tutorials/smart_ant/
[5] Lehne, P.H. and Petterson M., “An Overview of Smart Antenna Technology for Mobile
Communications Systems”, IEE Communications Surveys, Fourth Quarter
1999vol.2no.4,http://www.comsoc.org/livepubs/surveys/public/4q99issue/pdf/Lehne.pdf
[6] http://www.hdtvmagazine.com/forum/viewtopic.php?t=10289.
[7] http://searchmobilecomputing.techtarget.com/definition/smart-antenna.
[8] http://itlaw.wikia.com/wiki/Smart_antenna_technology.