3. Wireless Technologies
Abstract
The ability to communicate with
people has evolved remarkably since
Guglielmo Marconi first demonstrated
radio’s ability to provide continuous
contacts with ships. That was in 1897, since
then the wireless communication methods
and technologies have been enthusiastically
adopted by people throughout the world.
Particularly during past ten years, the mobile
radio communication industry has grown by
orders of magnitude, fueled by digital and
RF circuit fabrication improvements, new
large scale circuit integration and other
miniaturization technologies which make
portable radio equipment smaller, cheaper
and more reliable.
The cellular systems connect with
each other via mobile switching and directly
access the public switched telephone
networks. The most advertised advantage of
wireless communication system is that a
mobile user can make a phone call anywhere
and anytime.
The wireless technology has a greater
emphasis on cellular telephones i.e.
communication over long range. It has
several advantages over long distance
communication and thus has surpassed
wired communication successfully.
Mobile communication has evolved
significantly over a decade, starting from 1st
Generation commonly known as 1G to 2G,
3G and 4G transitioning from analog data
communication to digital mode, involving
several subsequent changes in the multiple
access techniques as well.
Wireless communication supports data
transfer from one device to the other with
the help of allotted spectrum and supported
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4. Wireless Technologies
range. These applications support starting
from the shortest range device that is
Infrared to Bluetooth, Wi-Fi and lastly
having a comparatively larger
communication range device amongst these
which is Wi-Max.
While wireless technology is
experiencing a paradigm shift in its
evolution at a rapid rate, an attempt is made
to highlight some of its essential features in
this paper.
Types of Communication:
Wired Communication.
Wireless Communication
• Wired Communication :
Wired communication is
transmission of data over wire based
communication technology. Some of the
examples are telephone network, cable
television, fiber optic communication.
Compared to wireless solutions, wired is
very cheap. The QoS is excellent as it
eliminates the need for establishing an end-
to-end connection every time. Using a group
of wires (like a telephone or Ethernet cable)
allows each conductor to handle a certain
amount of information.
On the negative side, rural areas
are still not wired for broadband Internet
connections. This forces users to subscribe
to satellite access. Ethernet cables can run a
maximum of 100 meters before the signal
needs to be boosted. This can cause
problems if you don't have an environment
that allows this luxury that the longer the
cable is, the more signal loss occurs and the
signal travels down the wire. This is why
special cables have been developed to help
preserve the strength of the signal. However,
the use of such technology usually comes at
a significantly higher price.
• Wireless communication :
Wireless communication is a transfer
of information over a distance without the
use of electrical conductors or wires. Some
of the examples include cellular telephones,
GPS, satellite television, wireless
networking. The range of wireless
technology is impressive. Wireless
technology may supplement or replace hard
wired implementations in security systems
for homes or office buildings. The best
known example of wireless technology is
the cellular telephone and modems. These
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5. Wireless Technologies
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.
On the negative side, wireless technology
suffers easily from interference.
Evolution Era:
Generations.
Multiple access techniques.
Generations:
1st
Generation (1G):
The first generation cellular system
and cordless telephone networks are based
on analog technology. All 1st
generation
systems use FM modulation, and cordless
telephones use a single base station to
communicate with a single port terminal. A
typical example of 1st
generation cellular
system is the Advanced Mobile Phone
Services (AMPS) used in the United
States.
1st
generation wireless systems
provide analog speech and inefficient, low-
rate data transmission between base station
and the mobile user. Also the speech signals
need to be digitized using a standard, time
division multiplex format for transmission
between the base station and the MSC and
are always digitized for distribution from
MSC to PSTN.
2nd
Generation (2G):
2nd
generation wireless systems employ
digital modulation and advanced call
processing capabilities. Examples of 2G
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6. Wireless Technologies
wireless systems include the Global System
for Mobile (GSM), the TDMA and CDMA
U.S. digital standards.
Second generation mobile telephones
were introduced in the nineties. 2-G
telephone systems were different because
of their use of digital circuit switched
transmission & the introduction of
advanced & quick telephone to network
signals. The introduction of 2-G systems
saw telephones move from historic 1G
telephones to small hand held items, which
were much more portable. This change was
made possible through improvements in
technology such as more advanced batteries
& energy efficient electronics.
The second generation mobile
telephones had several advantages over 1G
item. These included SMS messaging,
which initially became possible on GSM
networks & eventually on all digital
networks. SMS text messaging soon
became the communication method of
choice & the general public preferred
sending messages to placing voice calls.
All 2G systems use digital voice
coding and digital modulation. The systems
employ dedicated control channels within
the air interface for simultaneously
exchanging voice and control information
between the subscriber, the base station and
the MSC while a call is in progress. In
general 2G systems have been designed to
reduce the computational and switching
burden at the base station or MSC, while
providing more flexibility in the channel
allocation scheme.
3rd
Generation (3G):
The 3G wireless systems will evolve
from mature 2nd
generation systems. The aim
of 3rd
generation wireless networks is to
provide a single set of standards that can
meet a wide range of wireless applications
and provide universal access throughout the
world. Here, the distinctions between
cordless telephones and cellular telephones
will disappear and a universal personal
communicator will provide access to a
variety of voice, data and video
communication services.
Third generation systems will use the
Broadband Integrated Services Digital
Network (B-ISDN) to provide access to
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7. Wireless Technologies
information networks such as the internet
and other public and private data bases. It
will also carry many types of information
(voice, data and video), will operate in
varied regions such as dense or sparsely
populated and will serve both stationary and
vehicular users travelling at high speeds.
Some of the advantages touted by 3G
developers are Multi-mega bit internet
access, communications over Voice over
Internet Protocol (VoIP), voice activated
calls, unparalleled network capacity and
ubiquitous “always-on” access, ability to
receive live music, conduct interactive web
sessions and have simultaneous voice and
data access with multiple devices at the
same time using a single mobile handset.
Multiple Access Techniques:
Frequency Division Multiple
Access:
The FDMA channel carries only one
phone circuit at a time.
If an FDMA channel is not in use
then it sits idle and cannot be used by other
users to increase or share capacity. It is
essentially a wasted resource.
The bandwidths of FDMA channels
are relatively narrow as each channel
supports only one circuit per carrier.
The FDMA mobile unit uses
duplexers since both the transmitter and
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8. Wireless Technologies
receiver operate at the same time. This
results in an increase in cost of FDMA
subscriber units and base stations.
FDMA requires tight RF filtering to
minimize adjacent channel interference.
Time Division Multiple Access:
TDMA shares a single carrier
frequency with several users, where each
user makes use of no overlapping time
slots. The no. of time slots per frame
depends on modulation technique, available
bandwidth etc.
Data transmission for users of a
TDMA system is not continuous, but
occurs in bursts. This results in low battery
consumption, since subscriber transmitter
can be turned off when not in use.
In TDMA, the guard time should be
minimized. If the transmitted signal at the
edges of time slot is suppressed sharply in
order to shorten the guard time, the
transmitted spectrum will expands and
cause interference to adjacent channels.
TDMA has an advantage that it is
possible to allocate different numbers of
time slots per frame to different users. Thus,
bandwidth can be supplied on demand to
different users by reassigning time slots on
priority.
Code Division Multiple Access:
Many users of CDMA system share
the same frequency.
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9. Wireless Technologies
Unlike TDMA or FDMA, CDMA
has a soft capacity limit. Increasing the
number of users in a CDMA system raises
the noise floor in a linear manner. Thus,
there is no absolute limit on the number of
users in CDMA. Rather, the system
performance gradually degrades for all users
as the number of users is increased, and
improves as the number of users is
decreased.
Multipath fading may be
substantially reduced because the signal is
spread over a large spectrum.
Since CDMA uses co-channel cells,
it can use macroscopic spatial diversity to
provide soft handoff.
Advantages of Wireless
Communication:
Wireless communication has changed
the dynamics of the working environment
and workforce mobility. Without being
tethered to a fixed location or formal work-
based environment, professionals can work
anywhere. Wireless communication is
generally facilitated through the use of
wireless data cards or by connecting to the
Internet through private or public network-
based Wi-Fi hotpots or Wide Area Networks
(WANs) of large work centers and sprawling
educational campuses. Still other
professionals use PDAs, Machine Internet
Devices, Smart phones, etc. to connect
wirelessly to the Internet through the
network coverage area of
telecommunication service providers.
Convenience:
Wireless Networks can help make
connecting to the internet much more
convenient. You don't need an
Ethernet connection so you can
connect anywhere with a strong
enough signal and a wireless network
that is publicly accessible without a
password.
Devices:
Many different devices can be used
over a wireless network. These include
laptop computers, Cellular phones,
Blackberry devices, and handheld
computers.
Speed:
Wireless networks are less reliable
with connection speeds than
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10. Wireless Technologies
connections using an Ethernet cable.
This is due to the risk of dead spots
where the signal is either weak or non
existent.
Anywhere, Anytime Work:
Through wireless communication,
working professionals and mobile workers
can work and access the Internet just about
anywhere, anytime without the hassles of
wires and network cables.
Enhanced Productivity:
Workers, students, professionals
and others need not be constrained by wired
Internet connections or dial-up connectivity.
Wireless Internet connectivity options
ensures that work and assignments can be
completed anywhere and enhance overall
productivity of all concerned.
Remote Area Connectivity:
Workers, doctors and other
professionals working in remote-location
hospitals and medical centers can keep in
touch with anyone through wireless
communication. Non-profit organization
volunteers working in remote and
underserved areas can stay connected to the
outside world with the help of wireless
communication.
Emergency Alerts:
Through wireless communication,
many emergency situations and crisis
situations can be addressed quickly. Help
and other assistance can reach affected areas
quickly through early alerts and warnings
provided with the help of wireless
communication.
• Applications:
Infrared.
Bluetooth.
Wi-Fi (Wireless Fidelity).
WiMax (Worldwide Interoperability
for Microwave Access).
Infrared Technology:
Infrared is an invisible band of
radiation that exists at the lower end of the
visible electromagnetic spectrum. This type
of transmission is most effective when a
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11. Wireless Technologies
clear line-of-sight exists between the
transmitter and the receiver.
Two types of infrared WLAN
solutions are available: diffused beam and
direct beam. Direct beam WLANs offer a
faster data rate than the diffused beam
networks, but diffused beam networks are
more directional since they use reflected
rays to transmit/receive a data signal, thus
achieving lower data rates in the 1-2 Mbps
range. Infrared is a short range technology.
When used indoors, it can be limited by
solid objects such as doors, walls, etc. In
addition, the lighting environment can also
affect the signal quality. For example, loss of
communications might occur if there is a
large amount of sunlight or background light
in the environment. Fluorescent lights also
might contain large amount of infrared. This
problem may also be solved by using a high
signal power and an optimal bandwidth filter
which reduces the infrared signals coming
from outside sources.
It has advantages such as no
government regulations controlling use and
it is immune to electromagnetic and RF
interference but it is also accompanied by
several disadvantages like it is a short range
technology, signals cannot penetrate solid
objects, signal is affected by light, snow, ice
and fog etc. Also dirt can interfere with
infrared.
Bluetooth:
Bluetooth is an open standard that has
been embraced by over 1,000 manufacturers
of electronic appliances. It provides an ad-
hoc approach for enabling various devices to
communicate with one another within a
nominal 10 meter range. Named after King
Harald Bluetooth, the 10th
century Viking
who united Denmark and Norway, the
Bluetooth standard aims to unify the
connectivity chores of appliances within
personal workspace of an individual.
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12. Wireless Technologies
Bluetooth operates in the
2.4GHz band and uses a frequency hopping
TDD scheme for each radio channel. Each
Bluetooth radio channel has a 1MHz
bandwidth and a hop at a rate of
approximately 1600 hops/second. For long
data transmissions, particular users may
occupy multiple slots using the same
transmission frequency, thus slowing the
instantaneous hopping rate to below 1,600
hops/second.
Bluetooth promises to
uncomplicated the interconnectivity of
devices, easing the manufacturing woes and
end-user hassles. With embedded Bluetooth
technology, all sorts of devices including
cell phones, headsets and earpieces, digital
cameras and computers can easily
communicate with each other without
cables or setup.
Wi-Fi (Wireless Fidelity):
Wi-Fi is a means by which portable
devices can connect to the Internet
wirelessly. It works with no physical wired
connection between sender and receiver by
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13. Wireless Technologies
using radio frequency technology, a
frequency within the electromagnetic
spectrum associated with radio wave
propagation. When an RF current is supplied
to an antenna, an electromagnetic field is
created that then is able to propagate
through space. The cornerstone of any
wireless network is an access point. The
primary job of an access point is to
broadcast a wireless signal that computers
can detect and "tune" into. Wi-Fi is
supported by many applications and devices
including video game consoles, home
networks, PDAs, mobile phones, major
operating systems, and other types of
consumer electronics. Any products that are
tested and approved as "Wi-Fi Certified" (a
registered trademark) by the Wi-Fi Alliance
are certified as interoperable with each
other, even if they are from different
manufacturers.
In business environments, just like
other environments, increasing the number
of Wi-Fi access-points provides redundancy,
support for fast roaming and increased
overall network-capacity by using more
channels or by defining smaller cells. Wi-Fi
enables wireless voice-applications. Over
the years, Wi-Fi implementations have
moved toward "thin" access-points, with
more of the network intelligence housed in a
centralized network appliance, relegating
individual access-points to the role of mere
"dumb" radios. Outdoor applications may
utilize true mesh topologies. As of 2007 Wi-
Fi installations can provide a secure
computer networking gateway, firewall
intrusion detection system and other
functions.
WiMax (Worldwide
Interoperability for Microwave
Access):
WiMAX, meaning Worldwide
Interoperability for Microwave Access, is a
telecommunications technology that
provides wireless transmission of data using
a variety of transmission modes, from point-
to-multipoint links to portable and fully
mobile internet access. The technology
provides up to 3 Mbit/s broadband speeds
without the need for cables.
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14. Wireless Technologies
The bandwidth and range of WiMAX
make it suitable for the following potential
applications:
Connecting Wi-Fi hotspots to the
Internet.
Providing a wireless alternative to
cable and DSL for "last mile" broadband
access.
Providing data and
telecommunications services.
Providing a source of Internet
connectivity as part of a business continuity
plan. That is, if a business has both a fixed
and a wireless Internet connection,
especially from unrelated providers, they are
unlikely to be affected by the same service
outage.
Providing portable connectivity.
Comparison with Wi-Fi:
Comparisons and confusion between
WiMAX and Wi-Fi are frequent because
both are related to wireless connectivity and
Internet access.
• WiMAX uses spectrum to deliver a
point-to-point connection to the Internet.
Different 802.16 standards provide different
types of access, from portable (similar to a
cordless phone) to fixed (an alternative to
wired access, where the end user's wireless
termination point is fixed in location.)
• Wi-Fi uses unlicensed spectrum to
provide access to a network. Wi-Fi is more
popular in end user devices.
• WiMAX and Wi-Fi have quite
different quality of service (QoS)
mechanisms. WiMAX uses a mechanism
based on connections between the base
station and the user device. Each connection
is based on specific scheduling algorithms.
Wi-Fi has a QoS mechanism similar to fixed
Ethernet, where packets can receive
different priorities based on their tags. For
example VoIP traffic may be given priority
over web browsing.
• Wi-Fi runs on the Media Access
Control's CSMA/CA protocol, which is
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15. Wireless Technologies
connectionless and contention based,
whereas WiMAX runs a connection-oriented
MAC.
Conclusion:
A wireless communication system
has mobility of the devices within the
environment. It is a simple matter to relocate
a communicating device, and no additional
cost of rewiring and excessive downtime is
associated with such a move. It is also a
simple matter to add in a communication
device to the system or remove one from the
system without any disruption to the
remainder of the system. Other than the
initial outlay on setting up the cell sites, the
cost of running and maintaining a radio
based communications solution is minimal.
A wireless network is a great way
to expand the capabilities. Even a single
computer that sits on the same desk will
benefit from a wireless set up. Going
wireless really tidies up the workspace. A
wireless router is easy to tuck out of the
way, and replaces yards, or miles of cables.
In the early days of wireless, people
assumed losing the wires would degrade
signal quality or slow down operations. This
isn’t true at all. With a wireless set up, data
goes just as fast as it would with a wired set
up.
• References:
1. “Wireless Communications”-
Theodore Rappaport.
2. “Mobile Cellular
Telecommunications”-William CY
Lee.
3. www.google.com.
4. www.wikipedia.com.
G.C.O.E.A Page 15
![Wireless Technologies
WIRELESS TECHNOLOGIES
[Use of Wireless Technology in Mobile Communication]
Presented By
Nikhil S. Bhardwaj.
Electrical & Power (2nd
Year)
ID No. : (08003064)
Mob no-9766880962
nikhil.bhardwaj14@gmail.com
G.C.O.E. Amravati.
Gaurav P. Banginwar.
Electrical & Power (2nd
Year)
ID No. : (08003061)
Mob no-9561403645
gbanginwar@gmail.com
G.C.O.E. Amravati.
REGISTRATION ID: 812
G.C.O.E.A Page 1](https://image.slidesharecdn.com/a9155b69-8cbc-4441-9686-d64fb1bf3854-150413135015-conversion-gate01/85/wirelesstechnologies-1-320.jpg)
