NEED FOR WIRELESS COMMUNICATION

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WIRELESS COMMUNICATION

• INTRODUCTION
• NEED FOR WIRELESS COMMUNICATION
• DIFFERENCE BETWEEN WIRELESS AND CORDLESS
  COMMUNICATON
• EARLIER DEVELOPMENTS
• GENERATIONS OF THE WIRELESS COMMUNICATION
• FIRST GENERATION(1G)
• SECOND GENERATION(2G)
• 2G TECHNOLOGIES
• THIRD GENERATION(3G)
• 3G TECHNOLOGIES
• FUTURE GENERATION(4G)
• APPLICATIONS AND FUTURE ASPECTS

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Wireless communication is the transfer of
information over a distance without the use of
enhanced electrical conductors or "wires". The
distances involved may be short (a few meters as
in television remote control) or long (thousands
or millions of kilometers for radio
communications). When the context is clear, the
term is often shortened to "wireless". Wireless
communication is generally considered to be a
branch of telecommunications. It encompasses
various types of fixed, mobile, and
portable two-way radios, cellular
telephones, personal digital assistants (PDAs),
and wireless networking. Other examples
of wireless technology include GPS units, garage
door openers and or garage doors,
wireless computer mice, keyboards and headsets, sa
tellite television and cordless telephones.
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Wireless networking (i.e. the various types of
unlicensed 2.4 GHz Wi-Fi devices) is used to meet
many needs. Perhaps the most common use is to
connect laptop users who travel from location to
location. Another common use is for mobile
networks that connect via satellite. A wireless
transmission method is a logical choice to
network a LAN segment that must frequently change
locations. The following situations justify the
use of wireless technology To span a distance
beyond the capabilities of typical cabling, To
provide a backup communications link in case of
normal network failure, To link portable or
temporary workstations, To overcome situations
where normal cabling is difficult or financially
impractical, or To remotely connect mobile users
or networks.
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The term "wireless" should not be confused with
the term "cordless", which is generally used to
refer to powered electrical or electronic devices
that are able to operate from a portable power
source (e.g. a battery pack) without any cable or
cord to limit the mobility of the cordless device
through a connection to the mains power supply.
Some cordless devices, such as cordless
telephones, are also wireless in the sense that
information is transferred from the cordless
telephone to the telephone's base unit via some
type of wireless communications link. This has
caused some disparity in the usage of the term
"cordless", for example in Digital Enhanced
Cordless Telecommunications. In the last fifty
years, wireless communications industry
experienced drastic changes driven by many
technology innovations.
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The term "wireless" came into public use to refer
to a radio receiver or transceiver (a dual
purpose receiver and transmitter device),
establishing its usage in the field of wireless
telegraphy early on now the term is used to
describe modern wireless connections such as in
cellular networks and wireless broadband
Internet. It is also used in a general sense to
refer to any type of operation that is
implemented without the use of wires, such as
"wireless remote control" or "wireless energy
transfer", regardless of the specific technology
(e.g. radio, infrared,ultrasonic) that is used to
accomplish the operation. While Guglielmo
Marconi and Karl Ferdinand Braun were awarded the
1909 Nobel Prize for Physics for their
contribution to wireless telegraphy.
In 1885, T. A. Edison used a vibrator magnet for
induction transmission. In 1888, Edison deployed
a system of signaling on the Lehigh Valley
Railroad. In 1891, Edison obtained the wireless
patent for this method using inductance (U.S.
Patent 465,971). In the history of wireless
technology, the demonstration of the theory
of electromagnetic waves by Heinrich Hertz in
1888 was important. The theory of electromagnetic
waves was predicted from the research of James
Clerk Maxwell and Michael Faraday. Hertz
demonstrated that electromagnetic waves could
be transmitted and caused to travel through space
at straight lines and that they were able to
be received by an experimental apparatus. The
experiments were not followed up by
Hertz. Jagadish Chandra Bose around this time
developed an early wireless detection device and
help increase the knowledge of millimeter length
electromagnetic waves. Practical applications of
wireless radio communication and radio remote
control technology were implemented by later
inventors, such as Nikola Tesla.
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1G (or 1-G) refers to the first-generation
of wireless telephone technology, mobile telecommu
nications. These are the analog telecommunications
standards that were introduced in the 1980s and
continued until being replaced by 2G digital telec
ommunications. The main difference between two
succeeding mobile telephone systems, 1G and 2G,
is that the radio signals that 1G networks use
are analog, while 2G networks are
digital. Although both systems use digital
signaling to connect the radio towers (which
listen to the handsets) to the rest of the
telephone system, the voice itself during a call
is encoded to digital signals in 2G whereas 1G is
only modulated to higher frequency, typically
150 MHz and up. One such standard is NMT (Nordic
Mobile Telephone), used in Nordic
countries, Switzerland, Netherlands, Eastern
Europe and Russia. Others include AMPS (Advanced
Mobile Phone System) used in the United
States and Australia, TACS (Total Access
Communications System) in the United
Kingdom, C-450 in West Germany, Portugal and South
Africa, Radiocom 2000 in France,
and RTMI in Italy. In Japan there were multiple
systems. Three standards, TZ-801, TZ-802, and
TZ-803 were developed by NTT, while a competing
system operated by DDI used the JTACS (Japan
Total Access Communications System)
standard. Antecedent to 1G technology is
the mobile radio telephone, or 0G
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2G (or 2-G) is short for second-generation wireles
s telephone technology. Second generation 2G
cellular telecom networks were commercially
launched on the GSM standard in Finland by Radio
linja (now part of Elisa Oyj) in 1991. Three
primary benefits of 2G networks over their
predecessors were that phone conversations
were digitally encrypted, 2G systems were
significantly more efficient on the spectrum
allowing for far greater mobile phone penetration
levels and 2G introduced data services for
mobile, starting with SMS text messages. After 2G
was launched, the previous mobile telephone
systems were retrospectively dubbed 1G. While
radio signals on 1G networks are analog, and on
2G networks are digital, both systems use digital
signaling to connect the radio towers (which
listen to the handsets) to the rest of the
telephone system.
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2G technologies can be divided into TDMA-based
and CDMA-based standards depending on the type
of multiplexing used. The main 2G standards
are GSM (TDMA-based), originally from Europe but
used in almost all countries on all six inhabited
continents (Time Division Multiple Access). Today
accounts for over 80 of all subscribers around
the world. Over 60 GSM operators are also
using CDMA2000 in the 450 MHz frequency band
(CDMA450). IS-95 aka cdmaOne (CDMA-based,
commonly referred as simply CDMA in the US), used
in the Americas and parts of Asia. Today accounts
for about 17 of all subscribers globally. Over a
dozen CDMA operators have migrated to GSM
including operators in Mexico, India, Australia
and South Korea. PDC (TDMA-based), used
exclusively in Japan iDEN (TDMA-based),
proprietary network used by Nextel in the United
States and Telus Mobility in Canada IS-136 aka D-A
MPS (TDMA-based, commonly referred as simply
'TDMA' in the US), was once prevalent in the
Americas but most have migrated to GSM. 2G
services are frequently referred as Personal
Communications Service, or PCS, in the United
States. 2.5G services enable high-speed data
transfer over upgraded existing 2G networks.
Beyond 2G, there's 3G, with higher data speeds,
and even evolutions beyond 3G, such as 4G.
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International Mobile Telecommunications-2000
(IMT--2000), better known as 3G or 3rd
Generation, is a generation of standards
for mobile phones and mobile telecommunications
services fulfilling specifications by
the International Telecommunication
Union. Application services include wide-area
wireless voice telephone, mobile
Internet access, video calls and mobile TV, all
in a mobile environment. Compared to the
older 2G and 2.5G standards, a 3G system must
allow simultaneous use of speech and data
services, and provide peak data rates of at least
200 kbit/s according to the IMT-2000
specification. Recent 3G releases, often
denoted 3.5G and 3.75G, also provide mobile
broadband access of several Mbit/s to laptop
computers and smartphones.
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The following standards are typically branded
3G the UMTS system, first offered in 2001,
standardized by 3GPP, used primarily in Europe,
Japan, China (however with a different radio
interface) and other regions predominated by
GSM 2G system infrastructure. The cell phones are
typically UMTS and GSM hybrids. The original and
most widespread radio interface is called W-CDMA.
The latest release, HSPA, can provide peak data
rates up to 56 Mbit/s in the downlink in theory
(28 Mbit/s in existing services) and 22 Mbit/s in
the uplink. the CDMA2000 system, first offered in
2002, standardized by 3GPP2, used especially in
North America and South Korea, sharing
infrastructure with the IS-95 2G standard. The
cell phones are typically CDMA2000 and IS-95
hybrids. The latest release EVDO Rev B offers
peak rates of 14.7 Mbit/s downstream. The above
systems and radio interfaces are based on
kindred spread spectrum radio transmission
technology. While the GSM EDGE standard
("2.9G"), DECT cordless phones and Mobile
WiMAX standards formally also fulfill the
IMT-2000 requirements and are approved as 3G
standards by ITU, these are typically not branded
3G, and are based on completely different
technologies.
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A new generation of cellular standards has
appeared approximately every tenth year
since 1G systems were introduced in 1981/1982.
Each generation is characterized by new frequency
bands, higher data rates and non backwards
compatible transmission technology. 4G systems
are expected to appear in 2011-2013 (pre-4G
systems like LTE and mobile WiMAX have already
appeared), and fifth generation systems after
2020. The first release of the 3GPP Long Term
Evolution (LTE) standard does not completely
fulfill the ITU 4G requirements called
IMT-Advanced. First release LTE is not backwards
compatible with 3G, but is a pre-4G
or 3.9G technology, however sometimes branded
"4G" by the service providers.
4G refers to the fourth generation of cellular
wireless standards. It is a successor
to 3G and 2G families of standards. The
nomenclature of the generations generally refers
to a change in the fundamental nature of the
service, non-backwards compatible transmission
technology and new frequency bands. The first was
the move from 1981 analog (1G) to digital (2G)
transmission in 1992. This was followed, in 2002,
by 3G multi-media support, spread
spectrum transmission and at least 200 kbit/s,
soon expected to be followed by 4G, which refers
to all-IP packet-switched networks, mobile
ultra-broadband (gigabit speed) access
and multi-carrier transmission. Pre-4G
technologies such as mobile WiMAX and
first-release 3G Long term evolution (LTE) have
been available on the market since 2006 and
2009 respectively
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Security systems Wireless technology may
supplement or replace hard wired implementations
in security systems for homes or office
buildings. Television remote control Modern
televisions use wireless (generally infrared)
remote control units. Now radio waves are also
used. Cellular telephone (phones and
modems) Perhaps the best known example of
wireless technology is the cellular
telephone and modems. These instruments use radio
waves to enable the operator to make phone calls
from many locations worldwide. They can be used
anywhere that there is a cellular telephone site
to house the equipment that is required to
transmit and receive the signal that is used to
transfer both voice and data to and from these
instruments. Wi-Fi Wi-Fi is a wireless local area
network that enables portable computing devices
to connect easily to the Internet. Standardized
as IEEE 802.11 a,b,g,n, Wi-Fi approaches speeds
of some types of wired Ethernet. Wi-Fi hot spots
have been popular over the past few years. Some
businesses charge customers a monthly fee for
service, while others have begun offering it for
free in an effort to increase the sales of their
goods.
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Wireless energy transfer Wireless energy transfer
is a process whereby electrical energy is
transmitted from a power source to an electrical
load that does not have a built-in power source,
without the use of interconnecting
wires. Computer Interface Devices Answering the
call of customers frustrated with cord clutter,
many manufactures of computer peripherals turned
to wireless technology to satisfy their consumer
base. Originally these units used bulky, highly
limited transceivers to mediate between a
computer and a keyboard and mouse, however more
recent generations have used small, high quality
devices, some even incorporating Bluetooth. These
systems have become so ubiquitous that some users
have begun complaining about a lack of wired
peripherals. Wireless devices tend to have a
slightly slower response time than their wired
counterparts, however the gap is decreasing.
Initial concerns about the security of wireless
keyboards have also been addressed with the
maturation of the technology. Many scientists
have complained that wireless technology
interferes with their experiments, forcing them
to use less optimal peripherals because the
optimum one is not available in a wired
version. This has become especially prevalent
among scientists who use trackballs as the number
of models in production steadily decreases.