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SEMINAR I REPORT ON
COGNITIVE ACCESS TO TV WHITE SPACES
SUBMITTED TO UNIVERSITY OF PUNE
FOR PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF ENGINEERINGIn
Electronics and Telecommunication
(Microwave)
By
DAMODAR Y. TAMPULA
DEPARTMENT OF ELECTRONICS AND TELECOMMUNICATION
PUNE INSTITUTE OF COMPUTER TECHNOLOGY
PUNE 43
MAY 2014
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Department of Electronics and Telecommunication EngineeringPune Institute of Computer Technology, Pune43
CERTIFICATE
This is to certify that the Seminar II Report entitled
COGNITIVE ACCESS TO TV WHITE SPACES
has been successfully completed by
DAMODAR Y. TAMPULA
towards the partial fulfillment of the degree of Master of Engineering in Electronics and
Telecommunication (Microwave)as awarded by the University of Pune, at Pune Institute of
Computer Technologyduring the academic year 2014-15.
Prof. Dr. A.P. Dhande Prof. Dr. Y. Ravinder Prof. Dr. P.T. Kulkarni
Guide HOD, E&TC Dept Principal, PICT
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ACKNOWLEDGEMENTS
All that goes with this seminar is a compromise between theoretical consideration and
practical limitation. It involves all technical and non-technical experience from various sources. I
would like to express my feeling of gratitude towards the number of people who were
instrumental and supportive in successfully making the seminar report.
I also express my profound thanks to our Prof. Dr. Y. Ravinder, H.O.D of Electronicsand Telecommunication, PICT. Whose cheerful encouragement, invaluable suggestion &
technical support of vital importance have made me to complete this seminar successfully.
I would like to pay my sincere gratitude to our seminar coordinator, Prof. Mr. P.S
Varade for her valuable suggestions and help during the seminar work that I had undertaken.
I am thankful to our Principal Prof. Dr. P. T. Kulkarniand Prof. Dr. A.P. Dhandefor the constant
encouragement and assistance they provided me.
I cannot forget to express my immense sense of thankfulness towards Rupesh Pawar, non-
teaching staffof M.E. (E&TC)department for his extended co-operation towards me. I am also thankful
to all my friends who offered their helping hands at the time of need.
Damodar Y. Tampula
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CONTENTS
Abstract IList of Acronyms Ii
List of Symbols Iv
List of Figures Vi
List of Tables Vii
1 Introduction 1-101.1 Back ground 1
1.2 Relevance 2
1.3 Literature Survey 3
1.4 Motivation 6
1.5 Scope 7
1.6 Organization of the Report 7
2 Cognitive Radio2.1
2.2
2.3
3 Spectrum Sensing in Cognitive Radio
4 Applications and Future Challenges
5 Conclusions
6 References
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ABSTRACT
Traditional wireless communication systems have fixed transmission parameters. Their
transmission frequency is fixed and the same in every location and instant of time, determined by
regulatory policies. However, the recent popularity of telecommunications and wireless
communications has increased the usage of radio spectrum exponentially. In order to supply all
the demand and improve communication parameters and Quality of Service (QoS), new
technologies need to be developed. One of the attempts to solve the problem of spectrum lack is
Cognitive Radio (CR) and TV white space (TVWS) communications. Cognitive radio is being
intensively researched as the enabling technology for license-exempt access to the so-called TV
White Spaces (TVWS), large portions of spectrum in the UHF/VHF bands which become
available on a geographical basis after digital switchover. With the digital switchover, the so
called digital dividend or white spaces appeared in the TV bands. These white spaces are unused
frequency bands within the TV transmission spectrum. TVWS communications tries to reuse
these unused channels by adapting its transmission parameters to the environment and to avoid
causing interference to the primary users of the TV bands. In this way new frequency spectrum
for unlicensed users or devices is abilitated. Both in the US, and more recently, in the UK the
regulators have given conditional endorsement to this new mode of access.
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Abbreviations and Acronyms
BER Bit Error Rate
CDMA Code Division Multiple Access
List of SymbolsV Voltage Induced
Elevation angle of arrival
List of Figures
BER Bit Error Rate
CDMA Code Division Multiple Access
List of Tables
BER Bit Error Rate
CDMA Code Division Multiple Access
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CHAPTER 1
Introduction
1.1 Background
Internet usage has been rising exponentially in recent years, as developments in
technology have enabled increased data rates and connectivity in many parts of the world.
This has spawned new applications which large numbers of people have been embracing
in their personal and professional lives. Many people now rely on social networking and
Internet-based video-conferencing applications to keep in touch with friends and family,
or to search for all manner of information that would previously have been unavailable or
difficult to access. Many businesses have transformed the way in which they operate,
through innovative and effective use of the Internet as a powerful tool for interacting with
customers and suppliers. Governments and not-for-profit organizations are using the
Internet to reach people and interact with them in ways which previously would not have
been possible.
Despite all of this, however, there are still large numbers of people around the
world for whom Internet access is slow and cumbersome, or even non-existent, and for
whom many of the above-mentioned applications are unavailable. This is particularly true
in rural areas, where sparse populations and rugged landscapes often make it difficult or
expensive to roll out high-speed Internet connections. Many governments and other
organizations such as the ITU and UNESCO have recognized and acknowledged that
Internet connectivity is essential for the prosperity and survival of such communities, and
have committed to various targets aimed at improving coverage and data rates.
In the UK, BT has been equipping more and more of its telephone exchanges andstreet cabinets with fibre-based broadband infrastructure. However, extending the fibre-
based infrastructure is only part of the solution. Many homes, particularly those in rural
areas, are situated several miles from their local exchanges, with no cabinets in between,
and the achievable data rates are limited by the length of the copper-wire telephone lines
from the exchange to the home.
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One potential approach to solving this local loop line length problem is to use
wireless radio links instead, and with recent developments in spectrum management
policy emerging from the switch-over of TV broadcast transmissions from analogue to
digital, interest in so-called white space spectrum is gathering pace around the world.
Rural broadband is one of the key applications that could potentially benefit from making
use of white space spectrum.
1.2 Relevance
TV White Spaces is having its strong connection with microwave as it works in
the frequency range of few mega hertz. The subjects that are related to this topic are
cognitive radio and communication technology. TVWSs are of special interest because
of two main reasons: first of all, their propagation characteristics are especially good for
wireless communications, reducing propagation losses and hence, increasing coverage.
1.3
Literature Survey
A cognitive radio consists of a cognitive engine (CE), which contains algorithms
and toolboxes for radio environment sensing, machine-learning, reasoning and decision
making, and a configurable radio platform, which could be a Software Defined Radio
(SDR), that basically does what it is told by the CE. The concept of Cognitive Radio
(CR) was first described by Mitola and Maguire as transforming radio nodes from blind
executors of predefined protocols to radio-domain-aware intelligent agents that search out
ways to deliver the services that the user wants even if that user does not know how to
obtain them. The ideal CR knows everything about the user requirements, the capability
of the radio device, the network requirements and the external environment (including theradio environment). It will plan ahead and negotiate for the best part of the spectrum to
operate in and at the best power, modulation scheme, and so forth, and manage these
resources in real time to satisfy the service and user demands. The ideal CR is currently
at the early proof-of-concept stage research, with most of the work taking place in
universities.
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A much more developed form of the CR technology is cognitive radio for
dynamic spectrum access (DSA). The aim here is to achieve device-centric interference
control and dynamic reuse of radio spectrum based on the frequency agility and
intelligence offered by cognitive radio technology. This form of CR technology is
currently being intensely researched. However, there is also already significant industry
effort towards prototyping, standardization and commercialisation of the technology.
Important industry players with active R&D efforts in cognitive radio technology include
Alcatel-Lucent, Ericsson and Motorola from the mobile equipment industry, BT and
Orange from network operators, Philips and Samsung from the consumer electronics
industry, HP and Dell from the computer industry, and Microsoft and Google from the
Internet/software industry. Dynamic spectrum access may take place in several ways:
between a licensed primary system and a license-exempt secondary system, for example,
secondary spectrum access to digital TV or military spectrum, within the same primary
system, for example, micro-macro sharing of licensed spectrum in 3G/LTE femto-cells,
and finally among two primary systems, for example, real-time leasing and trading of
spectrum between two cellular operators.
The first form of dynamic spectrum access is arguably the most disruptive
application of the CR technology, as it enables license-exempt users (end-user devices
and base stations) to act as spectrum scavengers (Carlson and Telcordia have made DSA
technology devices). They can identify unused portions of licensed spectrum (also called
spectrum holes or White Spaces) and make opportunistic use of this spectrum for their
connectivity at times and/or locations where they are not used. Allowing the operation of
such scavenger promises to greatly increase the efficiency of spectrum usage by
preventing exclusively licensed spectrum from being wasted due to low spatial or
temporal usage. Mainly for this reason licensed-exempt cognitive access to certain
licensed bands is being keenly promoted by the US regulator, the (Federal
Communication Commission) FCC, and more recently also by Ofcom. The rationale is to
maximize the usage of licensed spectrum through secondary access by cognitive radios
and, at the same time, promote rapid introduction of new wireless technologies and
services without the need for setting aside any new spectrum for this purpose. Most
mobile operators see this form of cognitive access as highly disruptive to their current
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business model.
In the longer term (35 years), we expect that dynamic spectrum access based on
cognitive radio will go far beyond opportunistic spectrum access only. As a result of the
current trends in spectrum liberalisation, including the availability of licensed spectrum
for real-time trading, cognitive devices may be able to access a portfolio of different
types of spectrum for their connectivity. This spectrum portfolio may include several
different type of spectrum: licensed spectrum (e.g., in cellular bands), licensed-exempt
spectrum (in the ISM bands), as well as spectrum that is, acquired in real-time, either
through leasing or on a secondary basis. Devices with cognitive functionality will be able
to dynamically change their operating spectrum within this portfolio, accessing the best
available spectrum on a just-in-time basis. This may happen either upon instruction
from a base station or autonomously by devices themselves. Depending on the user and
network requirements devices may pool together and use several spectrum fragments and
vacate some or all of them when they are no longer required or when other more suitable
ones become available. These requirements may depend on context, application and
location and can include price, Quality of Service (QoS), and energy saving.
To date both in the UK and US regulators have committed to licence-exempt
cognitive access to the so-called TV White Spaces (TVWS). The TVWS spectrum
comprises large portions of the UHF/VHF spectrum that become available on a
geographical basis for cognitive access as a result of the switchover from analogue to
digital TV. The total capacity associated with TVWS is significant. According to
modelling studies commissioned by Ofcom over 50% of locations in the UK are likely to
have more that 150MHz of interleaved spectrum and that even at 90% of locations
around 100MHz of interleaved spectrum might be available for cognitive access [10]. In
addition to TVWS, the defence spectrum may provide another significant capacity
opportunity for license-exempt cognitive access. For example, around 30% of spectrum
below 15GHz is allocated to Defence in the UK. The UK (Ministry of Defence) MoD
had until the late 1990's access to spectrum at no or a low cost. However, following the
Cave Audit, the Government has committed to releasing a significant proportion of the
MOD's spectrum between 2008 and 2010. Results from a 2008 study by PA consulting
(commissioned jointly by MoD and Ofcom) suggest that there is significant scope for
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license-exempt use of the released spectrum using cognitive radio technology, both on a
spatial and a temporal basis. For example, low power cognitive devices could potentially
share with radar if the radar sweep can be detected and the transmission of the cognitive
device can be timed to avoid interference.
1.4 Motivation
Internet usage has been rising exponentially in recent years, as developments in
technology have enabled increased data rates and connectivity in many parts of the world.
This has spawned new applications which large numbers of people have been embracing
in their personal and professional lives that would previously have been unavailable or
difficult to access.
Recent developments in spectrum management policy emerging from the switch-
over of TV broadcast transmissions from analogue to digital, interest in so-called white
space spectrum is gathering pace around the world. Rural broadband is one of the key
applications that should potentially benefit from making use of white space spectrum.
As well as assessing the technical ability of the network to provide broadband
access, a further aim was to investigate the extent to which the white space broadband
transmissions would be able to co-exist with Digital Terrestrial Television (DTT)
transmissions without adversely affecting TV reception, and to what extent theoretical
predictions would match measurements made in the field.
1.5 Scope
This paper aims to review the state-of-the-art in technology, regulation, and
standardization of cognitive radio access to TVWS. It also examines the spectrum
opportunity, potential business applications, and some of the open research challenges
associated with this new form of access.
A number of rural communities have complained about the poor broadband
performance they receive from currently available commercial services. Their experience
is not unusual in other rural areas around the UK and elsewhere in Europe. The key
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attraction of TV white spaces in this application is the enhanced range which lower
frequencies enable (compared to the higher frequency bands traditionally used for
wireless broadband access). This extended range translates into fewer base stations being
required to cover a given area and, hence, lower coverage costs. An additional advantage
of licence-exempt access, which can be enabled through the use of geo-location
databases, is that rural communities would be free to provide their own wireless
networks.
1.6 Organization of Report
Contents of each chapter and report organizations is to be included briefly.
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CHAPTER 2
What is TV White Spaces?
2.1 Introduction
White Spaces are portions of radio spectrum which are not used by existing licensees at
all times or in all locations. Figure 1-1 illustrates the concept, showing unused white spaces
between licensed transmissions. With demand for wireless connectivity increasing, the
exploitation of white space is an attractive way of making more efficient use of radio spectrum.
In many countries, analogue television broadcasts are being switched off and replaced bymore spectrally efficient digital television transmissions, and the white spaces that exist in the
UHF TV band (470 MHz - 790 MHz in ITU Region 1) have good propagation and building
penetration characteristics.1 This potentially makes them suitable for use in rural broadband
applications, where transmission links may be several kilometres in length and may involve
challenging terrain such as hills, foliage, and water.
Figure1.1: TV White Spaces
Allowing licence-exempt devices to interleave their transmissions with those of licensed
users does, however, present challenges in ensuring that such unlicensed transmissions will not
adversely interfere with the licensed transmissions. The approaches adopted by the FCC and
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Ofcom differ slightly, but both involve the use of a regulator-approved database which White
Space Devices (WSDs) will need to consult before being allowed to access the spectrum.
Broadcast television services operate in licensed channels in the VHF and UHF portions
of the radio spectrum. The regulatory rules in most countries prohibit the use of unlicensed
devices in TV bands, with the exception of remote control, medical telemetry devices, and
wireless microphones. In most developed countries regulators are currently in the process of
requiring TV stations to convert from analogue to digital transmission. This Digital Switchover
(DSO) was completed in the US in June 2009, and is expected to be completed in the UK by
2012. A similar switchover process is also underway or being planned (or is already completed)
in the rest of the EU and many other countries around the world. After Digital Switchover a
portion of TV analogue channels become entirely vacant due to the higher spectrum efficiency of
digital TV (DTV). These cleared channels will then be reallocated by regulators to other services
through auctions.
In addition to cleared spectrum, after the DTV transition there will be typically a number
of TV channels in a given geographic area that are not being used by DTV stations, because such
stations would not be able to operate without causing interference to co-channel or adjacent
channel stations. However, a transmitter operating on such a locally vacant TV channel at a
much lower power level would not need a great (physical) separation from co-channel and
adjacent channel TV stations to avoid causing interference. Low power devices can therefore
operate on vacant channels in locations that could not be used by TV stations due to interference
planning. These vacant TV channels are known as TV White Spaces or Interleaved Spectrum in
the language of the UK regulator.
2.2 Sub Heading
2.2.1
Sub-Sub Heading
2.3 Figures
Figures are expected to be drawn using drawing software, imported from other simulations
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software in original. They should not be just scan, copy paste from the literature. Figures has to
be indexed and explained clearly as given in the followed.
x
y
z
Element lat( dx, d
y,d
z)
Direction of Plane Wave
Propagation
Fig: 2.1. Basic Antenna Array Geometry
Further, it is assumed that the signal )(ts is incident on an array of L isotropic elements shown
in Fig. 2.1, from a direction with, being the elevation and azimuth angles respectively.
Fig. 2.2 BER Performance of Basic Linear Array
N=2,=[150-30
060
0-70
080
0],=0.06,NI=15,M=5
(Co-ordinates in the block indicate X=SNR, Y=BER )
0 2 4 6 8 10 12 14 16 18 20-18
-16
-14
-12
-10
-8
-6
-4
-2
0
X: 15
Y: -9.907
X: 15
Y: -7.662
SNR(dB)
log10(BER)
BER-MMSE-BASIC
BER-MBER-BASIC
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All the graphs should be clearly visible with title, labels of each axis, legends, and line
markers as shown in Fig. 2.2 above. Graphs, results must be clearly interpreted in the text by
explaining the numerical, its significance and inferences as followed.BER performance of the
basic linear array of isotropic elements is carried out for various SNR and plotted in Fig. 2.2.
Here, the algorithmic parameter is set to 0.06 and the initial weight vector to [0.1+0i0.1+0i].
MBER solution converged to a lesser BER after 15 iterations that compared with MMSE
solution. At SNR=15, the BER is found to be 10-7.662
and the weight vector to be
[0.0228+0.0056i 0.0197+0.0127i] by MMSE approach, whereas, by MBER approach, BER is
10-9.907
and weight vector is [0.48000.7456+0.4623i].
2.4
Equations
All the equations must be typed either in MS equation editor or any other compatible
equation editors. Equations scanned, copied are not acceptable. Please refer the following
sample equation and follow the same uniformly throughout the report. All the symbols must be
explained when they appear for the first time. Every equation must be explained clearly. For
instance Eqn. (2.1) indicates that the equation number one in second chapter.
ww
w
ww
wH
qRRsbN
q H
sb
R
yy
Nyp
2
2
,
2 2
)(exp
1 2
11)1/;(
(2.1)
2.5 Tables
Table 2.1
Crossed dipole impedance matrix
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CHAPTER 3
Title of the Chapter 3
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CHAPTER 4
Applications and Future Challenges
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ReferencesBooks:
[1]
Constantine A. Balanis, Antenna Theory: Analysis and Design, 2ndEdition; John Wiley
Sons Inc. New York, 2001,pp12-130
Transaction/Journals:
Amir Ghasemi, Spectrum Sensing in Cognitive Radio Networks: Requirements,
Challenges and Design Trade-offs, IEEE Communications Magazine, April 2008.
International/National Conference Proceedings:
Moshe T. Masonta, David Johnson and Mjumo Mzyece,The White Space Opportunityin Southern Africa: Measurements with Meraka Cognitive Radio Platform, Tshwane
University of Technology, Pretoria, South Africa, 2011
Evanny Obregon, Lei Shi, Javier Ferrer, and Jens Zander,Experimental Verification of
Indoor TV White Space Opportunity Prediction Model Cognitive Radio Oriented
Wireless Networks & Communications(CROWNCOM), June, 2010
Cyrus Gerami, Narayan Mandayam, Larry Greenstein, Backhauling in TV White
Spaces, Global Telecommunication Conference(GLOBECOM 2010).
Standards/Patents:
[2] G.Brandli and M. Dick, Alternating current fed power supply, U.S.Patent 4 084 217,
Nov.4,1978
Technical Reports:
Maziar Nekovee, A Survey of Cognitive Radio Access to TV White Spaces,International Journal of Digital Multimedia Broadcasting, Volume 2010 (2010), Article
ID 236568, Accepted 6 April 2010
Website:
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[3] M. Duncan. Engineering Concepts on Ice. Internet: www.iceengg.edu/staff.html, Oct.
25, 2000 [Nov. 29, 2003].