presentation on w-fi 0051563107

8/8/2019 Presentation on W-fi 0051563107

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A Networking Technology that allowsthe connection of devices in wirelessmode.

Also called as Wireless LAN.

Called LAN because the range targetswithin

Office Campus

Building Just a House

Store


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Basic concept is same as Walkie Talkies.

Wi-Fi Networks, mostly uses radio &

infrared frequencies (RF) technology to

transmit & receive data at high speed.

A Wi-Fi hotspot is created by installing an

access point to an internet connection.

An access point acts as a base station.


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Wi-Fi is a short form of Wireless Fidelity.

It is a generic term that refers to the IEEE

802.11 communications standards for

Wireless Local Area Network (WLANs).

Inter operability standard for Wireless

Fidelity using IEEE802.11b/802.11a/802.11g standard.


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To develop a Medium Access control

(MAC) and Physical Layer (PHY)

specification for wireless connectivity

for fixed, portable and moving stations

within a local area.


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Appear in late 1999 Operates at 2.4GHz radio spectrum

11 Mbps (theoretical speed) - within 30 m

Range

4-6 Mbps (actual speed)

100 -150 feet range

Most popular, Least Expensive

Interference from mobile phones andBluetooth devices which can reduce the

transmission speed.


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Introduced in 2001 Operates at 5 GHz (less popular)

54 Mbps (theoretical speed)

15-20 Mbps (Actual speed) 50-75 feet range

More expensive

Not compatible with 802.11b


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Extension of 802.11b, with the samedisadvantages (security and interference)

Has a shorter range than 802.11b

Is backwards compatible with 802.11b so itallows or a smooth transition from 11b to 11g

Flexible because multiple channels can becombined for faster throughput, but limitedto one access point

Runs at 54 Mbps, but realistically about 20-25Mbps and about 14 Mbps when b associated

Uses frequency division multiplexingtechnology


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Wireless

Standards

802.11b 802.11g 802.11a

Frequency Range 2.4 GHz 2.4 GHz 5GHz

Max Speed 11 MBPS 54 MBPS 54 MBPS

Max Encryption 128 bit WEP 128 bit WEP 152 bit WEP

128 bit WEP

Distance Covered 300 ft 300 ft 100 ft

Potential User Entry level and

home networks

Larger networks,

small business

Large business

concerned with

security


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11B: 2.4 GHz, CCK modulationRates from 1 to 11Mbps, on market from 1999.

11A: 5.0 GHz, OFDM modulation

Rates from 6 to 56Mbps, on market from 2002.

11G: 2.4 GHz, CCK+OFDM modulation

Rates from 6 to 56Mbps, on market from 2003

and most popular today!!

2.4GHz & 5.0GHz are public available frequencies.


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Access Point : The AP is a wireless LAN transcieveror base station that connect one or many wirelessdevices simultaneously to the internet.

Wi-Fi Cards :They accept the wireless signal and

relay information. They can be internal and external.

(e.g. PCMCIA card for Laptop and PCI card forDesktop PC)

Safeguards : Firewalls and anti-virus softwareprotect networks from uninvited users and keepinformation secure


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AP-based topology (Infrastructure

Mode)

Peer-to-peer topology (Ad-hoc

Mode)

Point-to-multipoint bridge topology


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The client communicate through Access Point.

BSA-RF coverage provided by an AP.

ESA-It consists of 2 or more BSA.

ESA cell includes 10-15% overlap to allowroaming.


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AP is not required. Client devices within

a cell can

communicate directly

with each other.

It is useful for setting

up of a wireless

network quickly andeasily.


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This is used to connect a LAN in one building to aLANs in other buildings even if the buildings are miles

apart.These conditions receive a clear line of sight

between buildings. The line-of-sight range varies

based on the type of wireless bridge and antenna

used as well as the environmental conditions.


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Security

y Wi-Fi was not designed with robust

security in mind

Interference

y operates in unlicensed 2.4 GHz spectrum

y competes with other products e.g.

microwave ovens!y Speed Slower than cable

Scarcity of hotspots


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Performance decreases as distance increases

Indoor 40-300 feet

Outdoor 100 to 1000 feet

Indoor 100-300 feet

Outdoor 400 1500 feet

- doors, walls, furniture, ceiling

253 maximum number of client per AP, but15-20recommended


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The requirements for Wi-Fi network

security can be broken down into two

primary components:

Authentication

User Authentication

Server Authentication

Privacy


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Keeping unauthorized users off thenetwork

User Authentication

Authentication Server is used Username and password

Risk: Data (username & password) send before secure

channel established

Prone to passive eavesdropping by attacker

Solution Establishing a encrypted channel before sending

username and password


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Server Authentication

Digital Certificate is used

Validation of digital certificate occurs

automatically within client software


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Mobility

Ease of Installation

Flexibility

Cost

Reliability

Security

Use unlicensed part of the radio spectrum Speed


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Interference

Degradation in performance

High power consumption Limited range


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Home

Small Businesses

Large Corporation & Campus Travelers

Wireless ISP (WISP)


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