Abstract In infrastructure mode, network traffic
passes through a wireless access point.
In the past decade, wireless has grown from an
obscure and expensive curiosity into a The Concept:
practical and affordable networking
technology. Today’s most common wireless Wi-Fi is short for Wireless Fidelity and is
standard is 802.11b Ethernet, also called meant to be used generically when referring to
Wi-Fi (Wireless Fidelity). The 802.11b any type of 802.11 network, whether 802.11b,
standard is fast enough to be practical and 802.11a, 802.11g, dual-band, etc.
affordable enough for home networks. You Wi-fi is a wireless technology that uses radio
can buy the components to set up a wireless frequency to transmit data through the air.
network in nearly any store that sells
computers. An Access Point is a separate wireless unit,
which has the ability to extend from the router
The convenience of wireless is appealing— to maximize wireless reception. Up to 16
you don’t have to deal with running cable, and users can connect to one access point .It
you can move computers anywhere you want allows several wireless clients to connect to a
and still be connected to the network. Wireless single device.
is especially suited for use with laptop or Wi-fi hot spot is defined as any location in
notebook computers, offering users great which wireless technology both exists and is
freedom of movement. But enthusiasm for this available for use to consumers.
new technology sometimes leads to the
installation of a wireless network where a Wi-fi was intended to be used for wireless
wired network would be more effective, devices and LANS, but is now often used for
economical, and secure. Wireless has internet access.
shortcomings that make it ill suited for many
networks. Yet its popularity and ongoing
efforts to improve the technology make it a
promising option in the future.
The common usage of Wi-fi technology is for
laptop users to gain Internet access in
locations such as coffee shops, airports and so
Types of Wireless LANs:
A WI-FI network can operate in two
In ad-hoc mode, your computers talk directly
to each other and do not need an access point.
WI-FI Specification: Lower total cost of ownership –
Because of affordability and low
Wi-Fi is a wireless technology that uses install cost additionally
radio frequency to transmit data through the Mobile Users – Can access the
air. Corporate network from any public
hotspot using VPN
Quick/easy temp network access
Staff access to corporate network Range and Performance:
Patron internet access (hotspot)
Interconnecting two networks Performance decreases as distance increases.
802.11a (Wireless Ethernet)
Savings Indoor 40-300 feet
Expandability Outdoor 100 - 1000 feet
Advantages: 802.11b (Wireless Ethernet Refined)
Setup Cost – Reduced cabling Indoor 100-300 feet
required Outdoor 400 – 1500 feet
Flexibility – Quick and easy to setup
in temporary or permanent space. Interference - doors, walls, furniture,
Scaleable – Can be expanded with ceiling 253 maximum number of client per
growth AP, but 15-20 recommended.
Freedom – You can work from any
location that you can get a signal
Differences in wireless standards Coexistence: “wireless systems can be
collocated without significantly
Wireless Wi-Fi WiMax Mobile-Fi impacting the performance of either”
Standards (802.11) (802.16) (802.20)
Maximum 10 to 100 Bluetooth
54 Mbps 16 Mbps
Several A cable replacement radio frequency
Coverage 300 feet 50 Miles
Miles technology: low cost, modest
Licences No Both Yes transfer rate, and short range.
No Yes Yes Supports Pico nets of up to eight
Option active devices with three
Speed, synchronous connection-oriented
Pros Range, links asynchronous connectionless.
Pico net: an ad-hoc computer
Cons High Price network
It uses Frequency-Hop-Ping Spread
Spectrum (FHSS) at 1600hops/s
Applications: Data transfer rate 11Mb/s or higher
1. Wi-Fi with Bluetooth Technology Overview of Wi-Fi and Bluetooth
In this section, we will be discussing Characteristics
how our Wi-Fi Technology works together
with Bluetooth. Wi-Fi (802.11b)
Supports multipoint networking
Two prominent wireless technologies: Data types as broadcast, multicast,
1. WPAN: Wireless Personal Area
MAC address built-in, allowing
unlimited number of devices to be
Supports a short range (10m),
implemented in Bluetooth
Applications such as wireless It uses direct-sequence spread
headsets, PDAs, keyboards, spectrum
mice, etc. Both Wi-Fi and Bluetooth share the
same frequency band, 2.4Ghz
2. WLAN: Wireless Local Area
Supports wider range (100m), Issues of Coexistence
designed in Wi-Fi (802.11b)
Applications such as wireless Both Wi-Fi & Bluetooth operate at the
routers, wireless cards, same time within the same frequency
wireless printers, etc. band, they will interfere with each other,
creating in-band colored noise.
WPAN & WLAN are complementary The inference is called noise
Collocation of Wi-Fi and Bluetooth
become increasingly significant.
Noise: in-band noise & out-of-band Important milestone and enabler in the
noise growth of Wi-Fi beyond the PC market
In-band noise: the transmitter uses into
the undesired energy in frequencies – Wi-Fi Cellular Convergence
to transmit the desired signal. products
Out-band noise: the transmitter does – Voice over Wi-Fi applications
not use. – Consumer Electronics
White noise: interference from
multiple sources without their Features and Benefits of WMM
coordination. Power Save
Colored noise: interference
transmitted by two intentional Feature Benefit
radiators, behave in time & Individual applications More finely tuned
frequency (instead of the device power save
driver) decide when the mechanism
Occurrence of the interference:
client communicates with that is customized
An 802.11b receiver senses both the access point and to individual
Bluetooth and 802.11b signals at the how long it can doze applications
same time. The effect happens when
Bluetooth signal is within the 22-
data transfer than
MHz wide pass band of the receiver.
Uses fewer packets to legacy
A Bluetooth receiver senses both exchange data power save =
802.11b and Bluetooth signals at the lower power
same time. The inference occurs consumption
when the 802.11b signal is within the Coexists with legacy
Bluetooth receiver. power save devices and
The interference reduces the networks
performance of data transfer rate and – Legacy APs can Devices work in
packet lost. support WMM Power all Wi-Fi
Save clients (in legacy networks,
mode) & vice versa including legacy
2. WMM Power Save power save
(Wi-Fi Multimedia Power Save) – Both AP and client Easily
must have WMM upgradeable
Extends battery life for Wi-Fi devices Power Save to take
by increasing efficiency and flexibility advantage of advanced
of data transmission features
- Data indicates improvements
ranging from 15 – 40%
Uses mechanisms included in IEEE
In this paper, we have presented a new  Akshaya: A Kerala state initiative for
technology called Wi-Fi, its standards, Creating powerful social and economic
specifications, ranges and even its e-networks.http://www.akshaya.net/.
performance. Along with these we presented
how this Wi-Fi works together with other  IEEE P802.11, The Working Group for
technologies like Bluetooth and Multimedia. Wireless LANs.
To our knowledge, Our main conclusion is http://grouper.ieee.org/groups/802/11/.
that long-distance links can be planned well
for predictable performance using Wi-fi.  Radio laboratory handbook.
How-ever, any interference within the http://wireless.ictp.trieste.it
network can cause drastic reductions in /handbook/index.html,
performance. Interference can occur
between adjacent links even in the so-called  Pravin Bhagwat, Bhaskaran Raman,
non-interfering channels. This means that it and Dheeraj Sanghi. Turning 802.11
is important to develop the knowledge-base Inside-Out. In HotNets-II, Nov 2003.
for deployment planning.
Wi-Fi-based community networks have  Sanjit Biswas and Robert Morris.
received a lot of attention in the recent past. Opportunistic Routing in Multi-Hop
The same is necessary for long-distance Wireless Networks.
Wi-Fi deployments too, especially given its
potential to provide truly pervasive  Mobile Computing / Netwoking by
networking. We believe that our Ashoke .K Talukder & Roopa .R
measurement study is a significant step in Yavagal
this re-guard, and hope that the results will
be useful in future de-ployments and
We thank everyone who helped us at various