4g mobile communications wireless mobile communications ppt
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ABSTRACT: The number of subscribers for mobile
communications has increased much
faster than predicted. In the year 2010,
more than 1.8 billion mobile subscribers
are anticipated. The majority of traffic is
changing from speech oriented
communication to multimedia
communication. The major step from
second generation to third generation
and further to fourth generation was the
ability to support advanced and
wideband services including e-mail, file
transfers and distribution services like
radio, TV and software provisioning, In
this paper we address about the 4TH G
mobile communications.
The Fourth Generation (4G) Mobile
Communications not only focuses on the
data-rate increase and new air
interface.4G Mobile converges the
advanced wireless mobile
communications and high-speed wireless
access systems into an Open Wireless
Architecture (OWA) platform which
becomes the core of this emerging next
generation mobile technology. Based on
this OWA model, 4G mobile will deliver
the best business cases to the wireless
and mobile
industries,i.e.cdma2000/WLAN/GPRS
3-in-1 product,
WCDMA/OFDM/WLAN 3-in-1
product, etc. Asia-Pacific is the most
dynamic market of new generation
mobile communications with over $100
Billion businesses in the next decade.
The 4G mobile technology -
convergence of wireless mobile and
wireless access, will definitely drive this
growth. Any single-architecture wireless
system, including 3G, HSDPA, WiMax,
etc., is a transitional solution only, and
will be replaced by open wireless
architecture system very soon where
various different wireless standards can
be integrated and converged on this open
platform.
.
The advent of 4G wireless
systems has created many research
opportunities. The expectations from 4G
are high in terms of data rates, spectral
efficiency, mobility and integration.
Orthogonal Frequency Division
Multiplexing (OFDM) is proving to be a
possible multiple access technology to
be used in 4G. But OFDM comes with
its own challenges like high Peak to
Average Ratio, linearity concerns and
phase noise. This paper proposes a
solution to reduce Peak to Average Ratio
by clipping method. ATLAB as used to
generate the OFDM signal to prove that
clipping does reduce Peak to Average
Ratio.
INTRODUCTION:
The first operational cellular
communication system was deployed in
the Norway in 1981 and was followed
by similar systems in the US and UK.
These first generation systems provided
voice transmissions by using frequencies
around 900 MHz and analogue
modulation.
The second generation (2G) of the
wireless mobile network was based on
low-band digital data signaling. The
most popular 2G wireless technology is
known as Global Systems for Mobile
Communications (GSM). The first GSM
systems used a 25MHz frequency
spectrum in the 900MHz band.
Planning for 3G started
in the 1980s. Initial plans focused on
multimedia applications such as
videoconferencing for mobile phones.
When it became clear that the real killer
application was the Internet, 3G thinking
had to evolve. As personal wireless
handsets become more common than
fixed telephones, it is
clear that personal wireless Internet
access will follow and users will want
broadband Internet access wherever they
go.
.
2G 3G 4G
The objective of the 3G was to develop a
new protocol and new technologies to
further enhance the\mobile experience.
In contrast, the new 4G framework to be
established will try to accomplish new
levels of user experience and multi-
service capacity by also integrating all
the mobile technologies that exist (e.g.
GSM - Global System for Mobile
Communications, GPRS - General
Packet Radio Service, IMT-2000 -
International Mobile Communications,
Wi-Fi - Wireless Fidelity, Bluetooth).In
spite of different approaches, each
resulting from different visions of the
future platform currently under
investigation, the main objectives of 4G
networks can be stated in the following
properties:
Ubiquity;
Multi-service platform;
Low bit cost
To achieve the proposed goals, a very
flexible network that aggregates various
radio access technologies, must be
created. This network must provide high
bandwidth, from 50-100 MHz for high
mobility users, to 1GHz for low mobility
users, technologies that permit fast
handoffs, an efficient delivery.
Migrating to 4G: The fact that 4G mobile networks intend
to integrate almost every wireless
standard already in use, enabling its
simultaneous use and interconnection
poses many questions not yet answered.
The research areas that present key
challenges to migrate current systems to
4G are many but can be summarized in
the following: Mobile Station, System
and Service. To be able to use 4G
mobile networks a new type of mobile
terminals must be conceived. The
terminals to be adopted must adapt
seamless to multiple wireless networks,
each with different protocols and
technologies. Auto reconfiguration will
also be needed so that terminals can
adapt to the different services available.
This adaptation may imply that it must
download automatically configuration
software from networks in range.
Moreover terminals must be able to
choose from all the available wireless
networks the one to use with a specific
service. To do this it must be aware of
specifications of all the networks in
terms of bandwidth, QoS supported,
costs and respect to user preferences.
Terminal mobility will be a key factor to
the success of 4G networks. Terminals
must be able to provide wireless services
anytime, everywhere. This implies that
roaming between different networks
must be automatic and transparent to the
user. There are two major issues in
terminal mobility, location management
and handoff management Location
management deals with tracking user
mobility, and handling information
about original, current and (if possible)
future cells. Moreover it must deal with
authentication issues and QoS
assurances. Handoff management
primary objective is to maintain the
communications while the terminal
crosses wireless network boundaries. In
addition, 4G networks, in opposition to
the other mobile generations, must deal
with vertical and horizontal handoffs,
i.e., a 4G mobile client may move
between different types of wireless
networks (e.g. GSM and Wi-Fi) and
between cells of the same wireless
network (e.g. moving between adjacent
GSM cells). Furthermore, many of the
Services available in this new mobile
generation like videoconference have
restricted time constraints and QoS
needs that must not be perceptible
affected by handoffs. To avoid these
problems new algorithms must be
researched and a prevision of user
mobility will be necessary, so as to avoid
broadcasting at the same time to all
adjacent antennas what would waste
unnecessary resources. Another major
problem relates to security, since 4G
pretends to join many different types of
mobile technologies, as each standard
has its own security scheme, the key to
4G systems is to be highly flexible.
Services also pose many questions as 4G
users may have different operators to
different services and, even if they have
the same operator, they can access data
using different network technologies.
Actual billing using flat rates, time or
cost per bit fares, may not be suitable to
the new range of services. At the same
time it is necessary that the bill is well
understood by operator and client. A
broker system would be advisable to
facilitate the interaction between the user
and the different service providers.
Another challenge is to know, at each
time, where the user is and how he can
be contacted. This is very important to
mobility management. A user must be
able to be reached wherever he is, no
matter the kind of terminal that is being
used. This can be achieved in various
ways one of the most popular being the
use of a mobile-agent infrastructure. In
this framework, each user has a unique
identifier served by personal mobile
agents that make the link from users to
Internet.
Multi-technology Approach: Orthogonal Frequency Division Multiplexing (OFDM)
Open wire less Architecture(OWA)
Multiple-input multiple-output ( MIMO )
GENERIC MIMO AND OFDM:
Increasing demand for high performance
4G broadband wireless mobile calls for
use of multiple antennas at both base
station and subscriber ends. Multiple
Antenna technologies enable high
capacities suited for Internet and
multimedia services and also
dramatically increase range and
reliability. This design is motivated by
the growing demand for broadband
wireless Internet access. The challenge
for wireless broadband access lies in
providing a comparable quality of
service for similar cost as competing
wire line technologies. The target
frequency band for this system is 2 to 5
GHz due to favorable propagation
characteristics and low radio-frequency
(RF) equipment cost. The broadband
channel is typically non LOS channel
and includes impairments such as time
selective fading and frequency-selective
fading. Multiple antennas at the
transmitter and receiver provide
diversity in a fading environment. By
employing multiple antennas, multiple
spatial channels are created and it is
unlikely all the channels will fade
simultaneously.
OFDM is chosen over a single carrier
solution due to lower complexity of
equalizers for high delay spread
channels or high data rates. A broadband
signal is broken down into multiple
narrowband carriers (tones), where each
carrier is more robust to multipath. In
order to maintain orthogonality amongst
tones, a cyclic prefix is added which has
length greater than the expected delay
spread. With proper coding and
interleaving across frequencies,
multipath turns into an OFDM system
advantage by yielding frequency
diversity. OFDM can be implemented
efficiently by using FFT's at the
transmitter and receiver .At the receiver,
FFT reduces the channel response into a
multiplicative constant on a tone-by-tone
basis .With MIMO, the channel response
becomes a matrix. Since each tone can
be equalized independently, the
complexity of space time equalizers is
avoided.
Multipath remains an advantage for a
MIMO-OFDM system since frequency
selectivity caused by multipath improves
the rank distribution of the channel
matrices across frequency tones, thereby
increasing capacity.
OPENWIRELESSARCHITECTURE:
The 4G Mobile communications will be
based on the Open Wireless Architecture
(OWA) to ensure the single terminal can
seamlessly and automatically connect to
the local high-speed wireless access
systems when the users are in the
offices, homes, airports or shopping
centers where the wireless access
networks (i.e. Wireless LAN, Broadband
Wireless Access, Wireless Local Loop,
HomeRF, Wireless ATM, etc) are
available. When the users move to the
mobile zone (i.e. Highway, Beach,
Remote area, etc.), the same terminal
can automatically switch to the wireless
mobile networks (i.e.GPRS, W-CDMA,
cdma2000, TD-SCDMA, etc.).This
converged wireless communications can
provide the following advantages.
_
Greatly increase the spectrum efficiency
mostly ensures the highest data-rate to
the wireless terminal. Best share the
network resources and channel
utilization optimally manages the service
quality and multimedia applications. 3G
wireless LAN and other wireless access
technologies will be converged into 4G
mobile platform to deliver the best
infrastructure of mobile communications
with optimal spectrum efficiency and
resource management. In fact, this OWA
model had already been accepted by
most wireless industries, for example,
the W-CDMA/W-LAN/Bluetooth 3-in-1
terminal is being designed in many
companies. The global 4G Mobile R&D
focuses on the following Open Wireless
Architecture:
GOAL:
The goal of 4th Generation (4G) mobile
communications technologies is to
realize wireless communications at the
same high data rate as is made possible
through use of the fiber-optic
transmission systems that are available
today. Realization of 4G mobile
communications is foreseen in the early
2010s, but various precursor
technologies and services have been
appearing as of late. A scrutiny on the
market trends, along with a close watch
on carrier reaction as to the introduction
of the Mobile Number Portability
(MNP) system planned for October 24,
2006, is of vital importance at this time
for all those interested in this business
field
.
Conclusion: In this paper we
present the evolution of mobile
communications through all its
generations. From the initial speech
vocation to an IP-based data network,
several steps were made. From the analog
voice centric first generation to the digital
second generation, the goal was to
enhance the voice experience of a user, by
improving the quality of the
communication while using more
efficiently the installed capacity. At the
same time the enhanced mobility provided
by seamless handover and the additional
data communications capacity (although
very small) advanced and opened the
doors to future developments Some of the
developments was brought by generation
2.5 namely by GPRS, which improved
data communications by supporting IP in
the GSM infrastructure. With the third
generation the goal changed from voice-
centric to data-centric. Moreover total
ability became an objective to pursuit. In
this generation it is possible to combine
voice, lntermedia applications and
mobility in a never experienced manner.
However, the global mobility, while an
important objective, was never really
reached. At the same time new
applications demand more bandwidth and
lower costs. The newcomer fourth-
generation tries to address this problem by
integrating all different wireless
technologies. In spite of all the evolving
technologies the final success of new
mobile generations will be dictated by the
new services and contents made available
to users. These new applications must
meet user expectations, and give added
value over existing offers.
6. References: [1] “Mobile cellular, subscribers per
100 people”, International
Telecommunication Union Statistics,
2002
http://www.itu.int/ITU-D/ict/statistics
/at_glance/cellular02.pdf
[2] Kim, Y., Jeong, B.J., Chung, J.,
Hwang, C., Ryu, J.S., Kim, K., Kim,
Y.K., “Beyond 3G: Vision,
Requirements, and
Enabling Technologies”, IEEE
Communications Magazine, March
2003, pp. 120-124
[3] ITU-R PDNR WP8F, “Vision,
Framework and Overall Objectives of
the Future Development of IMT-2000
and
Systems beyond IMT-2000,” 2002.
[4] “2G – 3G Cellular Wireless data
transport terminology”, Arc Electronics
www.arcelect.com/2G-
3G_Cellular_Wireless.htm
[5] Schiller, J., “Mobile
Communications”, slides
http://www.jochenschiller.de/
[6] Tachikawa, Keiji, “A perspective on
the Evolution of Mobile
Communications”, IEEE
Communications Magazine,
October 2003, pp. 66-73
[7] Hui, Suk Yu, and Yeung, Kai Hau,
“Challenges in the Migration to 4G
Mobile Systems”, IEEE
Communications
Magazine, December 2003, pp. 54-
59eamless handover and the additional
data communications
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