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Evolution Toward 4G Communication System


Evolution Toward 4G
Communication System



Claudio E. Palazzi


Department of Computer Science, University of Bologna
Mura A. Zamboni 7, 40127 Bologna, Italy
E-mail: cpalazzi@cs.unibo.it





Advisor: Prof. Marco Roccetti



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1 - Introduction

The current status of the Internet as a widely used tool and the overwhelming
development and popularity of wireless access technology lead us to a future in which
the synergy between wireless and the Internet will be an integral part of our everyday
life. Virtual libraries, remote-working, video-telephony or voice over IP, on-line
games, traffic control, remote-medicine, video and music on demand, location based
resource discovery, navigation support, are only a few of the innumerable services
that will be available in every place and at every time [112][113][114]. People will be
allowed to be continuously connected during the whole day, regardless of their
location (eg, home, workplace, car, airport, hotel, etc) and utilizing a plethora of
traditional or new devices (eg, PCs, laptops, PDAs, cell phones, other handheld
device, next generation appliances, etc).

We are crossing a technology threshold that will revolutionize every area of our
lives. It will affect all of our everyday habits and businesses in ways far more
pervasive than most people may imagine. Devices that we use today for a limited
range of special purposes will become multiple application platforms. Even common
objects as wristwatches, cars, PDAs are evolving and their enhancement toward
multipurpose tools will accelerate as we move forward. Wristwatch capabilities could
be augmented making it able to communicate, download/play music, keep
personal/medical information, identify us to our car/home/devices, etc. Cars will be
elevated from a simple transportation vehicle to an office on the move, as well as an
information provider and entertainment center. Passengers will be allowed to access
the Internet, engage in teleconferencing, play distributed videogames, learn location
based information as low traffic paths to the destination or special offers for hotel
reservations, participate in ah hoc or mesh networks [81], etc. Paper money and coins
are going to be completely substituted by electronic transactions. Credit cards already
are more and more frequently used by customers for their real or on-line purchases.
The availability of always connected devices could further push commerce in this
direction. Pocket sized PDAs, in fact, could be enhanced to be an easy-to-use way of
payment. Customers will buy their objects and services connecting to a web page or
simply interacting their PDA with the cashier. Even tickets for events or travel will
disappear in the paper format: PDAs or equivalent multipurpose devices will be able
to provide the information required to authenticate the completed transaction.

In the aim of customers fully satisfying experience several issues have to be
guaranteed. A secure and efficient connectivity have to be always available even in
case of seamless switching between access network technologies. Moreover, it is
crucial that all the devices could interact one to each other to continue and
successfully complete a session started from another terminal. In order to clarify our
vision of the future with some examples lets imagine a student using his/her DSL
connection for streaming a compilation of music on-demand [95] on his/her
connected Hi-Fi at home. At a certain time the calendar function of his/her wristwatch
remind him/her an appointment with a friend in a cafeteria. Before leaving home,
he/she redirects eventual calls to his/her Video-telephony enabled PDA. After this,
he/she transfers the music stream on his/her PDA, automatically connected with the
home Wireless Local Area Network (WLAN), and then exits. Once the terminal is
inside the car and as far the car moves away from home, the WLAN signal becomes
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weaker and weaker and the device autonomously discovers and selects a better
network access, thus switching to UMTS [86]. The student continues enjoying the
selected songs, now directly from the high quality automobile speakers. Once selected
the destination, the on board computer in the car sets the most appropriate route until
a mutated traffic congestion information is received through the urban traffic grid
[83]; the navigation system suggests a deviation and, finally, a parking lot close to the
cafeteria. Sensors in the parking space detect that specific car by its unique identifier
chip and automatically charge the owner for the utilized time. Music stream is again
transferred to the PDA while the student leaves the automobile and starts hearing the
compilation from his/her Bluetooth [110] enabled earphones. Entering the local, the
Always Best Connected [13] system of the PDA automatically detects the presence of
the free WLAN of the cafeteria and switches to it. The student meets his/her friend at
a table and suspends the stream: he will be charged proportionally to the consumed
service. His/her friend looks at the multimedia player and suggests to immediately
download from the P2P network a new freely available enhanced software for
multimedia entertainment

We are leaving in a Communication Era where computers and connectivity are
becoming increasingly personal and essential. In this scenario, imagine also an
emergency situation when power goes out and all the Hot Spots and Cellular Base
Stations shut off thus impeding any kind of communications. Similar crisis conditions
in an urban area could occur when there is a chemical or nuclear disaster caused by
human error, plant break down, act of war or terrorist attack. Yet, this is the time
when communications are indispensable to control all the emergency operations and a
rapid deployable connectivity must be guaranteed. In these circumstances, satellites
combined with the use of sky objects flying above the crisis area, could represent the
only communication way left to the terrestrial infrastructure.

While the successful development of 2G technology was determined by a
combination of worldwide raising economical trend, a killer application as the Short
Message Services (SMS) and the possibility to use pre-paid cards to recharge the
credit, the same starting conditions lack in 3G, whose deployment has been further
delayed by the very expensive and time-consuming spectrum license auctions. This
situation coupled with the increasing popularity of the unlicensed spectrum family of
IEEE 802.11 standards [67] has been part of the impressive growth in the deployment
of WLAN access hot spots [85]. The high speed data service provided by WLAN and
its minimum initial investment and operational cost make this access technology a
natural co-player for the 3G systems: applications run indoor by 3G users could in
fact take benefit from being able to exploit the higher rate offered. Moreover, access
in hot spots could be free or flat rate for the user, thus giving another important reason
for switching type of connection while entering a WLAN.

The above depicted situation leads us toward an Always-On future. Not only,
people are going to demand the technology required to be Always Best Connected.
This new philosophy will permit users to exploit the locally best offered access for
their needs. In each moment and ubiquitously, a person will be able to chose between
the various connections available (wired access, Bluetooth, WLAN, 2.5G, 3G, etc) or
a combination of them, and between the various devices available depending on the
application requirements (eg, screen size, energy consumption, mobility, processing
capabilities, network interfaces, etc). Devices should be configurable such that usera
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only need to set some initial preferences in order to have, at any point in time, an
automatic and almost invisible best access choice. Indeed, communications utilizing
an IP-core network will be able to guarantee connectivity even between diverse access
technologies. Therefore, the 3G following generation of communication, namely 4G,
will not necessarily rely on an independent new radio infrastructure, instead its
peculiarity will be the integration of heterogeneous segments exploiting different
technologies within the common glue of the Internet.

In the following section we present a more precise description of the various
problems that arise in this scenario, while in section 3 we list the current state of the
art in the various technologies involved. In section 4 and 5 we show respectively the
work we have don