Advances in communications and media research volume 12

ADVANCES IN COMMUNICATIONS AND MEDIA RESEARCH

ADVANCES IN COMMUNICATIONS
AND MEDIA RESEARCH
VOLUME 12

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ADVANCES IN COMMUNICATIONS
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ADVANCES IN COMMUNICATIONS AND MEDIA RESEARCH

ADVANCES IN COMMUNICATIONS
AND MEDIA RESEARCH
VOLUME 12

ANTHONY V. STAVROS
EDITOR


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Published by Nova Science Publishers, Inc. † New York


CONTENTS
Preface
Chapter 1

Chapter 2

Chapter 3

Chapter 4

Chapter 5

vii

From Software to UWB Radio Communications:
A Brief Introduction
Vasilis Christofilakis, Giorgos Tatsis,
Constantinos I. Votis and Panos Kostarakis

1

Wideband Slotted Microstrip Antennas
for Modern Applications
Amel Boufrioua

35

Device-to-Device Communications
in 5G Networks: Technical Challenges
and Security Issues
Anargyros J. Roumeliotis
and Athanasios D. Panagopoulos

57

The Use of Mobile Devices to Support Young
People with Disabilities
Damian Maher and Kirsty Young
On the Singular Optimal Control
of Switched Systems
Vadim Azhmyakov
and Carlos M. Velezy

101

127


vi
Chapter 6

Index

Contents
A Pedagogical Proposal to Support the Teaching
of History with Audiovisual Content, Including
Video Game Advertising: The Example
of Assassin`s Creed IV: Black Flag
and Privateer Amaro Pargo
Enrique Carrasco Molina

145
165


PREFACE
In a society predicated on information, the media has a pervasive
presence. From government policy to leisure television, the information age
touches us all. The papers collected in this book constitute some of today's
leading analyses of the information industry. Together, these essays represent
a needed foundation for understanding the present state and future
development of the mass media. Current trends in communications as well as
media impact on public opinion are studied and reported on. Topics include a
brief introduction on software radio to ultra wideband radio communications;

wideband slotted microstrip antennas for modern applications; Device-toDevice (D2D) communication in 5G networks; the use of mobile devices to
support young people with disabilities; and singular optimal control of
switched systems. The final chapter is a proposal to support the teaching of
history with audiovisual content, including video game advertising.
Chapter 1 – Sixteen years after the dawn of the new millennium, strong
trends in telecommunications drive to adaptable wideband communication
systems. This effort is primarily motivated by two technological concepts:
software radio (SWR) and ultra wideband (UWB) communications. The
design, development and implementation of SWR involve either hardware or
software challenges such as analog to digital and digital signal processing
speed, power consumption, waveform application portability, software
modularity. Upon completing all these challenges and with the enormous
advantages of UWB communications, fully programmable, unlicensed, low
power radios, minimizing interfering with other systems, will be realized.
Furthermore, due to the large spectral coverage, UWB communications show
little loss of penetration in the materials, making it a perfect candidate for
emergency applications and harsh environments. This chapter focuses on SWR


viii

Anthony V. Stavros

and UWB technological concepts, and it presents benefits of this combination
as well as limitation and bottlenecks arising. Definition, scope, motivation and
a brief history of both technologies are also presented.
Chapter 2 – Today, the state of the art antenna technology allows the use
of different types and models of antennas, depending on the area of application
considered. With the rapid development of wireless communications, it is
desirable to design small size, low profile and wideband multi-frequency

planar antennas. The difficulty of antenna design increases when the number
of operating frequency bands increases. The slot loaded patch antenna is used
to overcome this problem. This chapter is focused on the multi-band
application of the microstrip patch antenna, which is analysed by introducing
different slots as U and L-shaped slots in rectangular and circular patches. The
effects of different physical parameters on the characteristics of the structure
are investigated. The results in terms of return loss, bandwidth and radiation
pattern are given. The proposed structures can be scaled to meet different
frequencies of wireless communication systems just by changing the
dimension of the main antenna. Comparisons of return loss and radiation
pattern for the same area of the rectangular and circular patches loaded with
slot is also given. Moreover, U-slot loaded rectangular patch antenna in a
stacked geometry with U-slot loaded circular patch antenna and vice versa are
analysed. The results show that dual wide bands can be achieved and a better
impedance matching for the upper and lower resonance can be obtained. Also,
it is observed that various antenna parameters are obtained as a function of
frequency for different values of slot length and width. It is easy to adjust the
upper and the lower band by varying these different antenna parameters. The
theoretical results using Matlab are compared with the simulated results
obtained from Ansoft HFSS which are in close agreement. Furthermore,
comparative studies between our results and those available in the literature is
done and showed to be in good agreement.
Chapter 3 – The present chapter deals with the concept of Device-toDevice (D2D) communication networks, their technical implementation and
security challenges. The first part is an introduction discussing briefly the
basic characteristics of D2D communications and their inclusion in the
upcoming 5G cellular systems as well as the importance of secure wireless
communications. Afterwards an overview of D2D framework follows and its
standardization history with future enhancements are described. Moreover, the
5G requirements and key enablers are indicated and the importance of the
implementation of D2D-enabled 5G systems is illustrated. Considering the

necessity for secure wireless communications various D2D security aspects


Preface

ix

are presented and the physical layer security techniques are mentioned
emphasizing in the secrecy capacity metric. Additionally, the integration of
secrecy capacity in D2D systems is surveyed and discussed. Finally, the
chapter concludes with future trends of D2D technology towards its
integration in the 5G communications.
Chapter 4 – Emerging evidence suggests mobile devices have the potential
to deliver students with disabilities a more equitable education, which is one of
the goals set down by the United Nations. The focus of this chapter is to
explore how mobile devices can be used to support young people with
communication disabilities and communication difficulties as a result of
isolation. The chapter draws upon international legislation and policy
documents, research literature and uses a specific case study to highlight the
implications and future directions.
Chapter 5 – This paper studies a singular case of Optimal Control
Problems (OCPs) governed by a class of switched control systems. The
authors propose a new mathematical formalism for this type of switched
dynamic systems and study OCPs with a quadratic cost functionals. The
original sophisticated optimization problem is next replaced by an auxiliary
“weakly relaxed” OCP. Our main result includes a formal proof of the local
convexity property of the obtained auxiliary OCP. The convex structure of the
OCP implies a possibility to apply a variety of powerful and relatively simple
optimization schemes to the sophisticated singular OCP involving switched
dynamics. The conceptual numerical approach the authors finally develop

includes an optimal switching times selection (“timing”) and a simultaneous
optimal switched modes sequence scheduling (“sequencing”).
Chapter 6 – Based on the analysis of a documentary included in the
advertising campaign to promote the game Assassin`s Creed IV: Black Flag
(2013), this study proposes to take, as a methodological resource, view and
analyze various audiovisual resources in order to improve teaching specific
aspects of the subjects of History in different education levels. Although such
games affect their access to age 18, certain content could be shown to students
with slightly lower ages.
The authors selected as an example a documentary on the life of Spanish
privateer born in Tenerife (Canary Islands), Amaro Pargo, a character who
lived during the golden age of piracy (XVIII Century) which has been
produced by the Spanish delegation of the French multinational Ubisoft.
The documentary recreates a scientific and archaeological study that
reveals the true tomb of Amaro Pargo, under the flagstones of the Church of


x

Anthony V. Stavros

Santo Domingo (La Laguna), and how the bones of the privateer were
exhumed.
Thanks to the explanation of Pargo`s life and socio-historical context we
can understand how marine life was, how were the trips and stopovers in the
Canary Islands and other islands, and how new colonial territories overseas
were described.
This chapter attempts to demonstrate the effectiveness of including in the
curriculum content and audiovisual pieces that recreate environments such as
those proposed by Assassin`s Creed universe, an imaginative entertainment

series that discovers interesting details that are inspired by various historical
periods as the French Revolution, or the Seven Years’ War, among others, and
include the active presence of some characters actually existed, as Amaro
Pargo (in the documentary) or pirate Blackbeard (in the videogame).


In: Adv. in Communications and Media. Vol. 12 ISBN: 978-1-53610-979-5
Editor: Anthony V. Stavros
© 2017 Nova Science Publishers, Inc.

Chapter 1

FROM SOFTWARE TO UWB RADIO
COMMUNICATIONS:
A BRIEF INTRODUCTION
Vasilis Christofilakis*, Giorgos Tatsis,
Constantinos I. Votis and Panos Kostarakis
Physics Department, Electronics-Telecommunications and
Applications Lab, University of Ioannina, Ioannina, Greece

ABSTRACT
Sixteen years after the dawn of the new millennium, strong trends in
telecommunications drive to adaptable wideband communication
systems. This effort is primarily motivated by two technological
concepts: software radio (SWR) and ultra wideband (UWB)
communications. The design, development and implementation of SWR
involve either hardware or software challenges such as analog to digital
and digital signal processing speed, power consumption, waveform
application portability, software modularity. Upon completing all these
challenges and with the enormous advantages of UWB communications,

fully programmable, unlicensed, low power radios, minimizing
interfering with other systems, will be realized. Furthermore, due to the
large spectral coverage, UWB communications show little loss of
*

Corresponding Author: e-mail: , ; Tel.: +30
26510 08542; fax: +30 26510 08674; www.telecomlab.gr.


2

Vasilis Christofilakis, Giorgos Tatsis, Constantinos I. Votis et al.
penetration in the materials, making it a perfect candidate for emergency
applications and harsh environments. This chapter focuses on SWR and
UWB technological concepts, and it presents benefits of this combination
as well as limitation and bottlenecks arising. Definition, scope,
motivation and a brief history of both technologies are also presented.

INTRODUCTION
The invention of the term “Software Radio” in the early 90’s [1] marked
the beginning of the transition from digital radios to fully programmable
software radio platforms. In the literature we find several definitions for the
term “Software Radio.” In [2] the concept of SWR is defined as follows:


“Software Radio” is an emerging technology, thought to build flexible
radio systems, multi-service, multi-standard, multi-band, reconfigurable
and reprogrammable by software.
The following definition is given by [3]:



“Software radio” means different things to different people - the common
ground perhaps is the recognition that the pace of advance in digital and
software technologies is not slackening and that these technologies will
have a profound impact upon future terminals, not simply mobile phone
terminals, but all kinds of consumer devices, ranging from multimedia
digital set-top boxes to new Internet-TV products.
In [1] Joseph Mitola defines software radio concept as follows:



“A software radio is a set of Digital Signal Processing primitives, a metalevel system for combining the primitives into communications systems
functions and a set of target processors on which the software radio is
hosted in real-time communications.”
In fact, all SWR's definitions are covered by the following statement [4]:



“The placement of the A/D/A converters as close to the antenna as
possible and the definition of radio functions in software are the hallmark
of the software radio.”


From Software to UWB Radio Communications

3

However, even if future state of the art A/D/A converters are capable of
capturing/transmitting wideband RF signals, something that should not be

ignored is the fact that, in practice, it is inevitable to eliminate hardwaredependent stages [5, 6]. Just for this reason the Software Radio (SWR) is an
ideal system, often found in the literature using the term Software Defined
Radio (SDR) 1, which is the functional version of the ideal Software Radio [7].
Ultra-Wideband (UWB) technology has recently attracted the attention of
both academia and industry for applications in wireless telecommunications.
This technology has many advantages, such as better immunity to multipath,
low power consumption, low interference. UWB systems promise high data
rates of the order of 100Mbps, suitable for multimedia applications. Also, due
to the large spectral coverage, UWB signals present small penetration loss
through materials and, therefore, are appropriate in short-range radar and
imaging systems, ground penetration radars, wall radar imaging, vehicular
radar systems for collision avoidance, guided parking, etc., surveillance
systems and medical imaging. Wireless communication applications are also
on the scope, including wireless home networking, UWB wireless computer
peripherals such as mouse, keyboard, speakers, printers, wireless USB,
wireless sensors networks etc. Back on April 2002 the Federal
Communications Commission (FCC) at USA approved the use of UWB
technology for wireless applications. The corresponding standards, the IEEE
802.15.3a (short range, high data rate) and the EEE 802.15.4a (low power, low
data rates) have been introduced [8].
The design, development and implementation of UWB-SWRs, capable of
operating within 3.1 to 10.6GHz band, with bandwidth at least 500MHz,
involves either hardware or software challenges such as wide bandwidth
ADC’s, digital signal processing throughput, power consumption, waveform
application portability, software modularity [9-13]. Upon completing all these
challenges and with the enormous advantages of UWB communications,
reconfigurable, unlicensed, low power radios, minimizing interfering with
other systems, will be realized. Especially in disaster or crisis areas, where
various military, police, fire department and other rescue forces are acting,
SWR is the ideal solution since it has the capability to access different bands

and frequency ranges of the radio spectrum. Additionally, in disaster or crisis
areas, the environment is likely to be altered due to demolished buildings, dust
and fire, making UWB communications a perfect candidate for such harsh
environments since they show little loss of penetration in the materials.
1

For simplicity reasons the abbreviation SWR is used instead of SDR.


4

Vasilis Christofilakis, Giorgos Tatsis, Constantinos I. Votis et al.

This chapter gives the reader an opportunity to understand Software Radio
and ultra wideband technological concepts as well as the tremendous
advantages arising from a UWB-SWR platform.

SWR OVERVIEW
An ideal software radio system essentially uses only four primitives which
are: the Antenna, the A/D/A, the Digital Signal Processing unit and finally the
User Interface (Figure 1). It should be clear to the reader that a multi-hardware
radio is not a software radio. As shown in Figure 2(a) a multi-hardware radio
system can support different operating standards having discrete hardware for
each channel. Each channel has a different carrier frequency and channel
bandwidth and is selected through frequency dependent passive components
both for heterodyne and homodyne (zero-IF) architectures. Homodyne
architectures are better than heterodyne concerning issues of complexity and
volume, but suffer from design problems such as I/Q mismatch and DC offset.
On the other hand, in the SWR all channels are digitized/transmitted through a
wideband A/D/A and the desired channel is digitally selected via the digital

signal processing unit (Figure 2(b)).

Figure 1. Ideal Software Radio.


From Software to UWB Radio Communications

Figure 2. (a) Multi-hardware Radio System, (b) Software Radio.

Figure 3. Software radio functions.

5


6

Vasilis Christofilakis, Giorgos Tatsis, Constantinos I. Votis et al.

As shown in Figure 3, the SWR Core consists of several modules
including security, frequency band, and modulation schemes. Every module
(or sub module) in the SWR core could be declared as a class. For example all
digital modulation schemes could be declared as a DModulation class.
Instances of this DModulation class are various modulation objects such as
fsk() and ask(). The bottom line is that in SWR every radio function can be
defined through software running on a fast digital signal processing unit (SWR
core).
The digital signal processing unit could be based on application specific
integrated circuit (ASIC), field programmable gate array (FPGA), digital
signal processor (DSP) or a combination of the above. In the literature we find
additional SWR based on a general processor [14, 15]. Usually, the digital

signal processing unit is distinguished according to five criteria [16]. These
are:








Programmability: The ability and method redefining the system to
perform all desired functions for different models
Integration: The ability to complete the most functions in a single
device, which directs to the reduction of complexity and size of the
device.
Development Cycle: The time from design to implementation of a
specific function, depending mainly on software tools and available
sources.
Performance: Execution time of specific functions
Power Consumption: Crucial for portable devices

An ASIC outperforms others in power consumption and performance, but
lacks significantly in programmability which is a primary function of a
reconfigurable software radio. The FPGAs have evolved from logical design
platforms in digital processing “machines.” An FPGA can achieve higher
performance compared to a DSP if properly optimized architecture is
implemented. However, to date, FPGAs have been used almost exclusively for
fixed point DSP designs. FPGAs have not been viewed as an effective
platform for applications requiring high performance floating point
computations [17]. Advanced floating-point computations such as matrix

inversion, matrix multiply and fast Fourier transform are extremely difficult to
implement in FPGAs, due to the large amount of data needed in the device
[18]. Older generation FPGAs had another disadvantage: during the operation
they could not be reconfigured [19]. New generation FPGAs allow run-time


From Software to UWB Radio Communications

7

fully or partially reconfiguration with time less than 1ms [20]. On the other
hand, run-time reconfiguration time of a DSP is much smaller and primarily
depends on DSP cycle time. State of the art DSPs have cycle time less than
1ns [21]. Even now there is not specific digital signal processing unit for SWR
architecture. A combination of DSP and FPGA could finally be a natural
choice [22-24]. Features, aiming SWR architecture for DSPs and FPGAs, are
summarized in the following Table.
Table 1. FPGA and DSP features
Feature
Programming Language

FPGA
VHDL, Verilog

Performance
Consumption
Re-configurability
Ease of programming

Depends on architecture

Depends on architecture
Full
Hardware/Software
orientation

DSP
C, Assembly, Modeling
Tools
Depends on cycle time
Depends on peripheral
Full
Software Orientation

Figure 4. RF spectrum.

The A/D/A primitive is also an essential SWR component, especially in
the case of the receiver, the implementation of which is at least four times
more difficult of the transmitter’s. The question evidently arisen is whether the
established technology can succeed the right sampling and quantization of RF
signals from 3 KHz to 300 GHz. For the case of simplicity let’s consider a
realistic portion (~3.3%) of the RF Spectrum from 3 KHz to 10GHz (Figure
4). Taking into account that the upper-frequency limit lies at 10 GHz, we
conclude that we need A/Ds with sampling rate at least 20 GS/sec, according
to the sampling theorem [25]. Based on the latest A/Ds surveys [26, 27], state
of the art A/Ds including various technologies and architectures such as Si
ICs, III-V ICs (semiconductors are synthesized using elements from third and
fifth group of periodic table), SuperCs, Flash, Pipe, SiGe, BiCMOS, SOI
CMOS, Nanoscale CMOS have reached such levels of sampling rates that can

8

Vasilis Christofilakis, Giorgos Tatsis, Constantinos I. Votis et al.

handle ultra wide band limited signals having frequency components lying
even around 20-40GHz [28, 29]. Even if the sampling frequency satisfies the
Nyquist criterion and A/D/A converters can handle above 10GHz full power
Input/output bandwidths [30, 31, 32] there are other parameters affecting the
performance of an A/D/A. Some of these parameters are bit resolution,
aperture jitter, differential nonlinearity error (DNL), integral nonlinearity error
(INL), full-power analog input bandwidth (FPBW), spurious free dynamic
range (SFDR), effective number of bits (ENOB). The parameters just
mentioned can play a significant role in real life and can affect the
performance of an A/D and thereby the implementation of an ideal SWR [33].

BRIEF HISTORY
Software radio’s origins date back to the military communications of the
70’s and 80’s. During that period, besides traditional subjects of cyber warfare,
for the first time the focus was on wideband digital techniques which, as
mentioned previously, are the beginning of SWR. The concept of SWR began
to spread substantially after 1995. A Pioneering military project was the
Speakeasy (the military software radio) [34] implemented in two phases from
1992 to 1995 and 1995 to 1997. The main goal of this ambitious project was
an operating frequency range from 2 MHz to 2 GHz and interoperability
among various waveforms that include STAJ, PACER bounce, Sincgars, Have
quick, EPLRS, JTIDS, GPS and technical Narrow Band modulation (AM /
FM) but also as spread spectrum direct sequence spread spectrum - DSSS
modulation and spread spectrum Frequency Hopping - FH [35]. Eventually,
the operating frequency range was between 4 to 400 MHz and the number of
waveforms supported much smaller [36]. The military organizations expressed

further interest in the SWR technology after the project Speakeasy thus
creating a group entitled “Programmable, Modular Communications System –
PMCS,” which recommended the creation of the Joint Tactical Radio System
(JTRS) [37]. The global interest in this technology led to the creation in 1996
of the Software Defined Radio Forum. The SWR Forum’s aim was to
accelerate the spread of technologies relevant to the SWR in wireless
telecommunications networks (civil, commercial, military) and participation in
the organization of universities, research institutions, companies, industries,
network operators, governments aiming prototyping architecture and platform
for SWR [38].


From Software to UWB Radio Communications

9

Significant boost to SWR technology was mainly achieved from 1995 to
2005 by research and academic institutions [5, 39-43], but also by
international projects such as FIRST (Flexible Integrated Radio Systems
Technology), SORT (Software Radio Technology), TRUST (Transparently reconfigurable Ubiquitous Terminal), CAST (Configurable radio with advanced
software Technology) [44].
Several manufacturers stepped up their efforts and after 2005 and for the
last ten years the SWR concept is applied in the commercial and military
market. Anywave Base Station was the first FCC-certified base station system
that fully implemented the base transceiver station (BTS) and base station
controller (BSC) entirely in software, running on a general-purpose server
[45]. Small-form factor (SFF) SDR handheld platform was a joint
development between Texas Instruments (TI), Xilinx and Lyrtech as well as a
host of leading software tool vendors [46]. Motorola Labs also presented a 100
MHz to 2.5 GHz Direct Conversion CMOS Transceiver for SWR applications

[47]. A software defined tactical radio that provides wideband data
performance, interoperability with fielded waveforms and covers 30 MHz to 2
GHz was presented by Harris co [48]. Another product was manufactured by
Rohde & Schwarz owing to different high-speed data modes and protocols as
well as different antijam modes for HF, VHF and UHF [49]. The European
Secure Software Defined Radio (ESSOR) is another promising programme
which started in 2008. The aim of the ESSOR programme is to develop a
European software-defined radio technology in order to improve the
capabilities for cooperation in joint inter-country operations. The first phase of
the EDA’s ESSOR programme has now successfully ended. In the first phase
of the ESSOR program, the parties were Indra from Spain, Radmor from
Poland, Saab from Sweden, Selex ES from Italy, Thales Communications &
Security from France and Bittium from Finland. The parties are currently in
negotiations about the second phase of the program. The most important goal
of the second phase is to achieve operational performance for the ESSOR
system [50]. Latest research, development and commercial efforts on this
promising technology are gathered every year in Wireless Innovation Forum
on Communications Technologies and Software Defined Radio [51].

SCOPE AND MOTIVATION
The idea of a unified communication system between commercial, civil,
governmental and military organizations certainly attracts numerous


10

Vasilis Christofilakis, Giorgos Tatsis, Constantinos I. Votis et al.

applications and leads to solving a variety of restrictions and bottlenecks. The
need for a radio system that can support and communicate with all existing

types of military radios is the backbone of military applications. A radio
system that can not only change the scrambling and encryption but also
modulation schemes and channel bandwidth is a highly interesting prospect. A
system like that could not only prevent hostile eavesdropping attemps, but also
be updated to perform better under certain conditions and different
environments.

Figure 5. 2002: The beginning of broadband (3G), 2008: Global penetration of
broadband reaches 10%, 2015: Global penetration of mobile broadband subscribers
reaches 47%.

Regarding the commercial sector, further details, such as size, cost, and
user friendliness play a major role. The problem of incompatibility between
different standards can also be resolved using SWR technology. As an
example, consider the incompatibility of cellular standards from first to the
third generation and beyond. The pie chart of Figure 5(2002) shows the
percentage of mobile subscribers among digital and analog cellular standards
in 2002 [52]. The first 3G network offered for commercial use was launched in


From Software to UWB Radio Communications

11

Japan by NTT DoCoMo. The network had the brand name FOMA and was
introduced in May 2001 on a W-CDMA technology. At the time, the overall
percentage of other standards such as IS-54, IS-136, usually known as DigitalAMPS (D-AMPS) or TDMA due to the type of multiplexing access, is shown
in Figure 5 (2002). IS-95 with 12% percentage was the first CDMA-based
digital cellular standard introduced by Qualcomm. All these standards have
some common features; on the other hand, each of them requires different

technology terminals and base stations (BS). The rapid change after 2006 to
broadband has modified the above percentages. In the year 2008, there were 4
billion global mobile-cellular subscriptions. Mobile broadband subscriptions
increased almost a thousand times from 2002 to 2008 with global penetration
from 0.01% to 10%. (Figure 5 (2008)) [53]. Mobile broadband is the most
dynamic market segment; globally, mobile-broadband penetration reaches
47% in 2015, a value that increased 12 times since 2007 [54]. Additionally,
new cellular standards and generations, 5G and beyond meant to be created
could be run on SWR base stations and mobile terminals. (Figure 6).

Figure 6. Transparency through old, existing and new cellular standards.


12

Vasilis Christofilakis, Giorgos Tatsis, Constantinos I. Votis et al.

Furthermore, lack of flexibility and upgrading can create significant
security issues. GSM was the prevalent mobile communication technology in
2002, with around 68% of the world-wide market share and over 200 million
subscribers. The over-the-air privacy of GSM telephone conversations is
protected by the A5 algorithm. The stronger A5/1 version was used by about
130 million customers in Western Europe and North America while another
100 million customers used the weaker A5/2 version. The approximate design
of A5/ leaked in 1994, and the exact design of both A5/1 and A5/2 was reverse
engineered by Briceno from an actual GSM telephone in 1999 [55]. Only 2
minutes of conversation time (data) and about a few seconds of processing on
a PC are fair enough to extract the conversation key [56]. Third Generation
cellular communications are protected by the new 128-bit A5/3 algorithm,
called Kasumi, a modified version of the MISTY cryptosystem. Although

A5/3 block cipher is the most recent version, several weaknesses have already
been identified [57]. Security vulnerabilities in mobile communications could
be easily resolved through over the air upgradability of SWR platforms.

UWB OVERVIEW
Ultra-Wideband (UWB) technology is a relatively new entry in the world
of telecommunications that has attracted the attention of the scientific
community. As its name implies, and according to the definition of the Federal
Communication Committee (FCC), a wireless scheme is considered as UWB
if the absolute bandwidth occupied is greater than 500 MHz or the fractional
bandwidth is over 20%. FCC also has set the limits of the maximum emission
power for indoor and outdoor applications in the United States (US), reserving
an unlicensed band between 3.1-10.6 GHz in which the maximum radiated
power is -41.3 dBm/MHz [58]. The spectral mask released by the FCC in 2002
is depicted in Figure 7. In European Union (EU) accordingly, the ETSI
(European Technical Standard Institute) and CEPT (European Conference of
Postal and Telecommunications) are still working for these limits. According
to the latest at the time report for indoor short-range devices (SRD) the
corresponding spectral mask is depicted in Figure 8 [59]. The EU limits are
more restricted than those in US, in a manner to avoid interference with other
technologies. Special mitigation techniques are required such as Low Duty
Cycle (LDC) abd Detect And Avoid (DAA) to permit the maximum power in
the bands 3.1-4.8 GHz and 8.5-9 GHz. The corresponding highest radiated