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Wi-Fi And Wi-MAX

A t i f R i y a z

R e g . N o : 1 1 0 1 1 4 4 3

S e c t i o n : O E 1 5 2

R o l l N o : O E 1 5 2 A 5 5

Term Paper

The term paper is brief article on Wi-Fi and Wi-Max, their

applications, advantages, disadvantages and their

comparison with other technologies.


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Table Of Contents

1) Abstract

2) Wi-Fi

a) Introductionb) History

c) Wireless Networking Components

d) Operation Modes

e) Radio Technology

f) Carrier Sense Multiple Access/Collision Avoidance

g) Operation Basics

h) Security

i) WEP Vulnerabilities

3) Wi-Max

a) Introduction

b) Technology Used

c) Working Of Wi-Max

d) Uses Of Wi-Max

e) Advantages Of Wi-Max

f) Disadvantages Of Wi-Max

4) Comparison Of Various Wireless Technologies


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Abstract

Wi-Fi

Wi-Fi was originally a brand licensed by the Wi-Fi Alliance to describe the embedded

technology of wireless local area networks (WLAN) based on the IEEE 802.11 standard. As of2007, common use of the term Wi-Fi has broadened to describe the generic wireless interface

of mobile computing devices, such as laptops in LANs.[citation needed] The term Wi-Fi was

chosen as a play on the term "Hi-Fi", and is often thought to be an abbreviation for wireless

fidelity. Wi-Fi and the Wi-Fi CERTIFIED logo are registered trademarks of the Wi-Fi Alliance, the

trade organization that tests and certifies equipment compliance with the 802.11x standards.

Common uses for Wi-Fi include Internet and VoIP phone access, gaming, and network

connectivity for consumer electronics such as televisions, DVD players, and digital cameras. In

spite of media reports about possible health risks from Wi-Fi, scientific studies have failed to

show a causal effect.

Wi-Fi networks use radio technologies called IEEE 802.11. These technologies have gone

through several generations since their inception in 1997. Wi-Fi is supported to different extents

under Microsoft Windows, Apple Mac OS and open source Unix and Linux operating systems.

Wi-Max

The broadband wireless access industry, which provides high-rate network connections to

stationary sites, has matured to the point at which it now has a standard for second-generation

wireless metropolitan area networks. Wireless MAN air interface, sets the stage for widespread

and effective deployments worldwide. WiMAX, or Worldwide Interoperability For Microwave

Access, is a wireless Internet service designed to cover wide geographical areas serving large

numbers of users at low cost. WiMAX is considered one of the best solutions for last mile

distribution. In contrast, wireless local area networks are designed to provide network access

within an office environment or a home or hotspots.


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Introduction

Wi-Fi is a popular technology that allows an electronic device to exchange data wirelessly

(using radio waves) over a computer network, including high-speed Internet connections. The

Wi-Fi Alliance defines Wi-Fi as any "wireless local area network (WLAN) products that are

based on the Institute of Electrical and Electronics Engineers' (IEEE) 802.11 standards".However, since most modern WLANs are based on these standards, the term "Wi-Fi" is used in

general English as a synonym for "WLAN".

Wi-Fi, or Wireless Fidelity, is freedom: it allows you to connect to the Internet from your couch at

home, a bed in a hotel room or at a conference room at work without wires. How? Wi-Fi is a

wireless technology like a cell phone. Wi-Fi enabled computers send and receive data indoors

and out: anywhere within the range of a base station. And the best thing of all, its fast. In fact,

its several times faster than the fastest cable modem connection.

However, you only have true freedom to be connected anywhere if your

computer is configured with a Wi-Fi CERTIFIED radio (a PC Card or similar device). Wi-Ficertification means that you will be able to connect anywhere there are other Wi-Fi CERTIFIED

products-whether you are at home, the office or corporate campus, or in airports, hotels, coffee

shops and

A device that can use Wi-Fi (such as a personal computer, video game console, smartphone,

tablet, or digital audio player) can connect to a network resource such as the Internet via a

wireless network access point. Such an access point (or hotspot) has a range of about 20

meters (65 feet) indoors and a greater range outdoors. Hotspot coverage can comprise an area

as small as a single room with walls that block radio waves or as large as many square miles

this is achieved by using multiple overlapping access points.

"Wi-Fi" is a trademark of the Wi-Fi Alliance and the brand name for products using the IEEE

802.11 family of standards. Only Wi-Fi products that complete Wi-Fi Alliance interoperability

certification testing successfully may use the "Wi-Fi CERTIFIED" designation and trademark.

Wi-Fi has had a checkered security history. Its earliest encryption system, WEP, proved easy to

break. Much higher quality protocols, WPA and WPA2, were added later. However, an optional

feature added in 2007, called Wi-Fi Protected Setup (WPS), has a flaw that allows a remote

attacker to recover the router's WPA or WPA2 password in a few hours on most

implementations. Some manufacturers have recommended turning off the WPS feature. The

Wi-Fi Alliance has since updated its test plan and certification program to ensure all newly-

certified devices resist brute-force AP PIN attacks.

History

802.11 technologies has its origins in a 1985 ruling by the US Federal Communications

Commission that released the ISM band for unlicensed use. In 1991 NCR Corporation with


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AT&T invented the precursor to 802.11 intended for use in cashier systems. The first wireless

products were under the name WaveLAN.

Vic Hayes has been called the "father of Wi-Fi". He was involved in designing the initial

standards within the IEEE.

A large number of patents by many companies are used in 802.11 standards. In 1992 and 1996,Australian organization the CSIRO obtained patents for a method later used in Wi-Fi to

"unsmear" the signal. In April 2009, 14 tech companies agreed to pay CSIRO $250 million for

infringements on the CSIRO patents.. This led to Wi-Fi being attributed as an Australian

invention, though this has been the subject of some controversy. The CSIRO won a further

$220 million settlement for Wi-Fi patent infringements in 2012 with global firms in the United

States required to pay the CSIRO licensing rights estimated to be worth an additional $1 billion

in royalties.

In 1999, the Wi-Fi Alliance was formed as a trade association to hold the Wi-Fi trademark under

which most products are sold.

Cellular Phones use 824-MHz to 894-MHz frequency bands. Some obstacles to this in the near

future are missing roaming and authentication in SIM cards and radius, the narrowness of the

available spectrum and the limited range. i.e., Wi-Fi will directly compete against the cellular.

WIRELESS NETWORKING COMPONENTS

Wi-Fi is a friendly term for IEEE 802.11b Ethernet standard. It operates in the unlicensed

frequency band of 2.4 Ghz with a maximum data rate of 11 Mbps.

IEEE 802.11b wireless networking consists of the following components:

Stations

A station (STA) is a network node that

is equipped with a wireless network device. A

personal computer with a wireless network

adapter is known as a wireless client. Wireless

clients can communicate directly with each

other or through a wireless access point (AP).

Wireless clients are mobile.

Wireless Access Points

A wireless AP is a wireless network node that acts as a bridge between STAs and a

wired network. A wireless AP contains:

Figure 1 Wirless Station


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At least one interface that connects the wireless AP to an

existing wired network (such as an Ethernet backbone).

A wireless network device with which it creates wireless

connections with STAs.

IEEE 802.1D bridging software, so that it can act as atransparent bridge between the wireless and wired networks.

The wireless AP is similar to a cellular phone network's

base station. Wireless clients communicate with both the wired

network and other wireless clients through the wireless AP.

Wireless APs are not mobile and act as peripheral bridge devices that extend a wired network.

OPERATION MODES

IEEE 802.11 defines two operating modes: Ad hoc mode and Infrastructure mode.

AD HOC MODE: In ad hoc mode, also known as

peer-to-peer mode, wireless clients communicate

directly with each other (without the use of a

wireless AP). Two or more wireless clients who

communicate using ad hoc mode form an

Independent Basic Service Set (IBSS). Ad hoc

mode is used to connect wireless clients when a

wireless AP is not present.

INFRA STRUCTURE MODE: In infrastructure

mode, there is at least one wireless AP and one wireless client. The wireless client uses the

wireless AP to access the resources of a

wired network. The wired network can be an

organization intranet or the Internet,

depending on the placement of the wireless

AP.

A single wireless AP that supports one or

multiple wireless clients is known as a Basic

Service Set (BSS). A set of two or more

wireless APs that are connected to the same

wired network is known as an Extended

Service Set (ESS). An ESS is a single logical

Figure 2 Access Point

Figure 3 The ad-hoc network structure in the 802.11

protocol

Figure 4 The infrastructure network structure in the 802.11

protocol


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network segment (also known as a subnet), and is identified by its Service Set Identifier (SSID).

If the available physical areas of the wireless APs in an ESS overlap, then a wireless client can

roam, or move from one location (with a wireless AP) to another (with a different wireless AP)

while maintaining Network layer connectivity.

RADIO TECHNOLOGY

Wi-Fi network uses radio technology called IEEE 802.11b to provide secure, fast,

reliable, wireless connectivity. 11b defines the physical layer and media access control (MAC)

sublayer for communications across a shared, wireless local area network (WLAN). At the

physical layer, IEEE 802.11b operates at the radio frequency of 2.45 gigahertz (GHz) with a

maximum bit rate of 11 Mbps. It uses the direct sequence spread spectrum (DSSS)

transmission technique. At the MAC sublayer of the Data Link layer, 802.11b uses the carrier

sense multiple access with collision avoidance (CSMA/CA) media access control (MAC)

protocol

CARRIER SENSE MULTIPLE ACCESS/COLLISION AVOIDANCE

The basic access method for 802.11 is the Distributed Coordination Function (DCF)

which uses Carrier Sense Multiple Access / Collision Avoidance (CSMA / CA). This requires

each station to listen for other users. If the channel is idle, the station may transmit. However if it

is busy, each station waits until transmission stops, and then enters into a random back off

procedure. This prevents multiple stations from seizing the medium immediately after

completion of the preceding transmission.

Figure 5 CSMA/CD Back-off Algorithm

Packet reception in DCF requires acknowledgement as shown in figure. The period between

completion of packet transmission and start of the ACK frame is one Short Inter Frame Space

(SIFS). ACK frames have a higher priority than other traffic. Fast acknowledgement is one of the

salient features of the 802.11 standard, because it requires ACKs to be handled at the MAC

sublayer.


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Transmissions other than ACKs must wait at least one DCF inter frame space (DIFS)

before transmitting data. If a transmitter senses a busy medium, it determines a random back-

off period by setting an internal timer to an integer number of slot times. Upon expiration of a

DIFS, the timer begins to decrement. If the timer reaches zero, the station may begin

transmission. However, if the channel is seized by another station before the timer reaches

zero, the timer setting is retained at the decremented value for subsequent transmission.

OPERATION BASICS

When a wireless adapter is turned on, it begins to scan across the wireless frequencies

for wireless APs and other wireless clients in ad hoc mode. Assuming that the wireless client is

configured to operate in infrastructure mode, the wireless adapter chooses a wireless AP with

which to connect. This selection is made automatically by using SSID and signal strength and

frame error rate information. Next, the wireless adapter switches to the assigned channel of the

selected wireless AP and negotiates the use of a port. This is known as establishing anassociation.

If the signal strength of the wireless AP is too low, the error rate too high, or if instructed

by the operating system (in the case of Windows XP), the wireless adapter scans for other

wireless APs to determine whether a different wireless AP can provide a stronger signal or

lower error rate. If such a wireless AP is located, the wireless adapter switches to the channel of

that wireless AP and negotiates the use of a port. This is known as reassociation.

Reassociation with a different wireless AP can occur for several reasons. The signal can

weaken as either the wireless adapter moves away from the wireless AP or the wireless AP

becomes congested with too much traffic or interference. By switching to another wireless AP,the wireless adapter can distribute the load to other wireless APs, increasing the performance

for other wireless clients. You can achieve contiguous coverage over large areas by placing

your wireless APs so that their signal areas overlap slightly. As a wireless client roams across

different signal areas, it can associate and reassociate from one wireless AP to another,

maintaining a continuous logical connection to the wired network.

SECURITY

Because wireless is a shared medium, everything that is transmitted or received over a

wireless network can be intercepted. Encryption and authentication are always considered when

developing a wireless networking system. The goal of adding these security features is to make

wireless traffic as secure as wired traffic. The IEEE 802.11b standard provides a mechanism to

do this by encrypting the traffic and authenticating nodes via the Wired Equivalent Privacy

(WEP) protocol.

The IEEE 802.11 standard defines the following mechanisms for wireless security:


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Authentication through the open system and shared key authentication types

Data confidentiality through Wired Equivalent Privacy (WEP)

Open system authentication does not provide authentication, only identification using the

wireless adapter's MAC address. Open system authentication is used when no authentication is

required. Some wireless APs allow the configuration of the MAC addresses of allowed wirelessclients. However, this is not secure because the MAC address of a wireless client can be

spoofed.

Shared key authentication verifies that an authenticating wireless client has knowledge

of a shared secret. This is similar to preshared key authentication in Internet Protocol security

(IPsec). The 802.11 standard currently assumes that the shared key is delivered to participating

STAs through a secure channel that is independent of IEEE 802.11. In practice, this secret is

manually configured for both the wireless AP and client. Because the shared key authentication

secret must be distributed manually, this method of authentication does not scale to a large

infrastructure mode network (for example, corporate campuses and public places, such as malls

and airports). Additionally, shared key authentication is not secure and is not recommended for

use.

WEP VULNERABILITIES

Not long after WEP was developed, a series of independent research studies began to

expose its cryptographic weaknesses. Even with WEP enabled, third parties with a moderate

amount of technical know-how and resources could breach WLAN security. Three key

difficulties were identified:

1. WEP uses a single, static shared key. It remains the same unless a network

administrator manually changes it on all devices in the WLAN, a task that becomes ever more

daunting as the size of the WLAN increases.

2. At the time of its introduction, WEP employed a necessarily short 40-bit encryption

scheme. The scheme was the maximum allowed by US export standards at that time. In 1997,

the US government deemed the export of data cryptography to be as threatening to national

security as the export of weapons of mass destruction. By necessity, Wi-Fi security had to be

weak if the specification was to be adopted as an international standard and if products were to

be freely exported.

3. Other technical problems contributed to its vulnerability, including attacks that could lead

to the recovery of the WEP key itself.

Together, these issues exposed that WEP was not sufficient for enterprise-class

security.


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Wi-Max

Introduction

WiMAX (Worldwide Interoperability for Microwave Access) is a telecommunications protocol that

provides fixed and mobile Internet access. The current WiMAX revision provides up to 40Mbit/s[with the IEEE 802.16m update expected to offer up to 1 Gbit/s fixed speeds. The name

"WiMAX" was created by the WiMAX Forum, which was formed in June 2001 to promote

conformity and interoperability of the standard. The forum describes WiMAX as "a standards-

based technology enabling the delivery of last mile wireless broadband access as an alternative

to cable and DSL"

Technology Used:

The IEEE standard for WiMax is 802.16 and falls under the category of wireless metropolitan

area network. WiMax operates on two frequency bands:

1. 2-11GHz

2. 10-66GHz

And has a range of 50 Km with the speed of 80Mbps.

This enables the smaller wireless LANs to be interconnected by WiMax creating a large

wireless MAN. Networking between can be achieved without the need of expensive cabling. It

also enables to provide high speed wireless broadband access to users.

WiMAX refers to interoperable implementations of the IEEE 802.16 wireless-networks standard

, in similarity with Wi-Fi, which refers to interoperable implementations of the IEEE 802.11

Wireless LAN standard . The WiMAX Forum certification allows vendors to sell their equipment

as WiMAX (Fixed or Mobile) certified, thus ensuring a level of interoperability with other certified

products, as long as they fit the same profile.

The IEEE 802.16 standard forms the basis of 'WiMAX' and is sometimes referred to colloquially

as "WiMAX", "Fixed WiMAX", "Mobile WiMAX", "802.16d" and "802.16e." Clarification of the

formal names are as follow:

The 802.16a specification, which is an extension of IEEE802.16, covers bands in the

2GHz-to-11GHz range

802.16-2004 is also known as 802.16d, which refers to the working party that hasdeveloped that standard. It is sometimes referred to as "Fixed WiMAX," since it has no support

for mobility.

802.16e-2005, often abbreviated to 802.16e, is an amendment to 802.16-2004. It

introduced support for mobility, among other things and is therefore also known as "Mobile

WiMAX".


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Mobile WiMAX is the WiMAX incarnation that has the most commercial interest to date and is

being actively deployed in many countries. Mobile WiMAX is also the basis of future revisions of

WiMAX.

The WiMax Technology provides:

1. The high speed of broadband service

2. Wireless rather than wired access, that makes it lot less expensive than cable or DSL.

3. Broad coverage like the cell phone network instead of small WiFi hotspots.

Working Of WiMax

WiMAX technology works little different than WiFi technology. In wifi computers can be

connected through wireless LAN card to nearby access point, wireless router or any Hotspot, it

does not works this way when we talk about connectivity in WiMAX. WiMAX network

connectivity constitutes of two parts, one can define as WiMAX tower or WiMAX booster, it isknown as WiMAX Base station, whereas the other portion is WiMax receiver. Lets talk about

them in little details for better understanding the working.

1. WiMAX base station: As name explains base station is place where WiMax signals are

broadcasted. It consists of electronic devices and WiMax Tower. This tower works exactly like

GSM network phones towers standing high up in the air to broadcast radio signals. WiMAX

tower base station can cover up 10Km radius. In theory it suggests to cover a lot more distance

than just 10Km, it can reach some where about 50 km (30 miles), but in fact due to certain


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geographical limitations it goes as far as 10 km approx. 6 mils. Any wireless connecting device

for WiMAX will connect to WiMAX network if fallen in to the range.

2. WiMAX Receiver: It is device or devices which receives the signals from WiMAX base

station and connects to the WiMAX networks. These devices are usually stand alone Antenna

or PCMCIA slot card for laptops or computers. Connecting to WiMAX base stations works as

similar as connection of Wifi to access point works, the only difference is that WiMAX covers

much wider area.

Uses Of WiMax:

1. An internet service company could put a tower within a few miles of your home. Its

service may be purchased and you can decide on either a modem, upgraded computer with

built-in WiMAX circuitry or a PCMCIA card for your existing computer. Intel has promised to

install WiMAX architecture in all of its computer chips starting in 2005 and provide mobility by

2007. This integration of WiMAX capabilities into products should further deflate the cost ofWiMAX related services. Speed will be faster than cable, costs will be much less because the

provider will neither have to install - nor maintain - expensive cable plant

2. WiMAX uses line-of-site to transmit an internet signal to a second tower or as backhaul.

It also is said to use non line-of-site mode for the last mile, to reach urban and rural residences

and businesses.

3. WiMAX technology is used to transmit to several WiFi Hot Spots. Recently, during the

Tour de France, journalists were provided with WiMAX technology from Intel and France

Telecom/Orange. The system served WiFi Hot Spots with WiMAX being used for backhaul.

The installation at each stage took less than an hour, giving reporters better-than-DSL speedsto submit t information

4. WiMAX is an access solution for urban locations with high-density populations

5. Providing portable mobile broadband connectivity across cities and countries through a

variety of devices.

6. Providing a wireless alternative to cable and DSL for "last mile" broadband access.

7. Providing a source of Internet connectivity as part of a business continuity plan


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Advantages Of WiMax

1. Wimax Coverage

The single station of Wimax can operate and provide coverage for hundred of users at a timeand manage sending and receiving of data at very high speed with full of network security.

2. Wimax High Speed

The High speed of connectivity over long distance and high speed voice makes it more

demanded in hardly populated areas plus compacted areas.

3. Multi-functionality within Wimax Technology

Wimax Technology perform a variety of task at a time such as offering high speed internet,

providing telephone service, transformation of data, video streaming, voice application etc.

4. Potential and development

Wimax Technology is a great invention for new Era because Wimax has enough potential for

developing and opportunity to offer various types of services for new generation. Now you can

connect internet anywhere and browse any site and make possible online conference with

mobile internet, multimedia application never let you bored, IPTV stay you up to date etc.

5. Stay in touch with end user

Wimax network always keep stay in touch with your friends and all others using same Wimax

network because it provide absolute communication service to the end users to make possible

rich communications

6. Wimax Infrastructure

Wimax infrastructure is very easy and flexible therefore it provides maximum reliability of

network and consent to actual access to end users.

7. Wimax, cheap network

Wimax is a well known wireless network now days because it provide a low cost network

substitute to internet services offered via ADSL, modem or local area network.

8. Wimax and Wi-Fi

The Wimax network providing much higher speed and very long range as compared to WiFi

Technology.

9. Smart antenna and Mesh Topology


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The use of smart antenna in Wimax network offering high quality widest array which enable you

to make possible communication on long route without any encryption. It offers 2.3, 2.7, 3.3,

3.8GHz frequency ranges. The use of Mesh topology in Wimax network for the expansion is an

extensive spectrum of antennas for commercial as well as for residential users.

10. Ultra wide Band

The unique and excellent infrastructure of Wimax is offering Ultra-Wideband. Its exclusive

design is providing range from 2 to 10 GHz and outstanding time response.

Disadvantages Of WiMax

1. Within line-of-site

One could have the speed of 10 Mbps at 10 kilometers. In the urban environment (without the

optical visibility) users can have 10 Mbps at two kilometers. If users are moving, the speed candrop significantly.

2. Bandwidth is shared among users

Bandwidth is shared among users in a given radio sector. If there are many

users in one sector, they will have lower speed. Users could have 2, 4, 6, 8, or 10 Mbps of the

shared bandwidth.

3. Bad weather conditions

Bad weather conditions such as rain could interrupt the signal.

4. Interfarence

Other wireless equipment could cause interference.

5. Power Consumption

WiMAX is a very power-consuming technology and requires significant electrical support.

6. Installation And Operational Cost

High installation and operational cost.


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Comparison Of Various Wireless Technologies

Bluetooth Wi-Fi (a) Wi-Fi (b) Wi-Fi (n) WiMax

Standard 802.15 802.11a 802.11b 802.11n 802.16Frequency(GHz)

2.45 5 2.4 2.4 2-66

Speed (Mbps) 0.72 54 11 54 80

Range 10m 50m 100m 100m 50Km

Advantages Low Cost Speed Low Cost Speed Speed, Range

Disadvantages

Range Cost Speed Cost,Range

Cost

Network Pear to Pear Pear toPear &IP

Pear toPear &IP

Pear toPear &IP

IP

IP NetworkConnectivity No Yes Yes Yes Yes

Application CableReplacement

LAN,Internet

LAN,Internet

LAN,Internet

Metro AreaBroadbandInterconnectivity

SpectrumType

Unlicensed Unlicensed

Unlicensed

Unlicensed

Licensed

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