Wimax vsWi-fi

WiMAX Versus Wi-Fi

A Seminar Report

Submitted by

Reshma MR

In partial fulfillment for the award of the degree

Of

BACHELOR OF TECHNOLOGY

In

COMPUTER SCIENCE AND ENGINEERING

SCHOOL OF ENGINEERING

COCHIN UNIVERSITY OF SCIENCE & TECHNOLOGY

COCHIN-682022

August 2010

DIVISION OF COMPUTER ENGINEERING

SCHOOL OF ENGINEERING

COCHIN UNIVERSITY OF SCIENCE AND
TECHNOLOGY

COCHIN– 682022

CERTIFICATE

Certified that this is a bonafied record of the Seminar work entitled

“WIMAX versus Wi-Fi”

done by

RESHMA.M.R

of the VIIth semester, Computer Science and Engineering in the year 2010 in partial

fulfillment of the requirements to the award of Degree of Bachelor of Technology in

Computer Science Engineering of Cochin University of Science and Technology.

Dr.David Peter Mr.Sudheep Elayidom

Head of the department Seminar Guide

ACKNOWLEDGEMENT

It is with greatest pleasure and pride that I present this report before you. At this moment of
triumph, it would be unfair to neglect all those who helped me in the successful completion of
this seminar.

First of all, I would like to place myself at the feet of God Almighty for his everlasting
love and for the blessings & courage that he gave me, which made it possible to me to see
through the turbulence and to set me in the right path.
I would also like to thank our Head of the Department, Mr. David Peter S for all the help and
guidance that she provided to me.

I am grateful to my guide, Mr. Sudheep Elayidom.M , for his guidance and whole hearted
support and very valued constructive criticism that has driven to complete the seminar
successfully.

I would take this opportunity to thank my friends who were always a source of encouragement.

ABSTRACT

Wi-Fi, which stands for “Wireless Fidelity”, is a radio technology that networks computers so
they connect to each other and to the Internet without wires .Users can share documents and
projects, as well as an Internet connection among various computer stations, and easily
connect to a broadband Internet connection while traveling. By using a Wi-Fi network,
individuals can network desktop computers, laptops and PDAs and share networked
peripherals like servers and printers. A Wi-Fi network operates just like a wired network,
without the restrictions imposed by wires. Not only does it enable users to move around be
mobile at home and at work , it also provides easy connections to the Internet and business
networks while traveling .The technologies used in this field are one of the best in the
wireless space . It is fairly easy to set up a Wi-Fi enabled network at home or a small office.

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-point links to portable internet access [citation needed].
The technology provides up to 75 Mbits/ symmetric broadband speed without the need for
cables. The technology is based on the IEEE 802.16 standard (also called Broadband
Wireless Access). 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”.s

Table of Contents

Chapter No. Title Page
No.

1 Introduction 1
2 Wireless Networking 2
2.1 Wireless Standards 3
3 What is Wi-Fi 4
3.1 How Wi-Fi 6
3.2 Wi-Fi Technology Standards 9
3.3 Advantages of Wi-Fi 10
3.4 Disadvantage of Wi-Fi 11
4 What is WiMAX? 13
4.1 How WiMAX works 14
4.2 Backhaul 16
4.3 Types of WiMAX 17
4.4 Advantages of WiMAX 19
4.5 Disadvantages of WiMAX 19
5 WiMAX Versus Wi-Fi 20
5.1 Uses of Wi-Fi versus WiMAX 22
5.2 Capacity of Wi-Fi versus WiMAX 22
5.3 Technical difference of the two
standards 23
6 Conclusion 26
7 References 27

LIST OF FIGURES

Fig no. FIGURES Page no:
1 Wi-Fi and WiMAX logo 1

2 Wireless network 2

3 802 Wireless standards 3

4 WLAN Standards 4

5 How Wi-Fi works 7

6 WMAN Standards 13

7 How WiMAX works 15

8 A WiMAX tower 16

List of Tables

Tab no. Tables Page no
1 IEEE 802.11 Radio Link Interface 10

2 Summary of 802.16 Radio Link 19

3 Mobile Standards Compared 24

4 Comparison WiMAX and Wi-Fi 25

Wi-MAX Versus Wi-Fi

CHAPTER 1

INTRODUCTION

WiMAX is not a technology, but rather a certification mark, or 'stamp of approval' given
to equipment that meets certain conformity and interoperability tests for the IEEE 802.16 family
of standards. A similar confusion surrounds the term Wi-Fi, which like WiMAX, is a
certification mark for equipment based on a different set of IEEE standards from the 802.11
working group for wireless local area networks (WLAN). Neither WiMAX, nor Wi-Fi is a
technology but their names have been adopted in popular usage to denote the technologies
behind them. This is likely due to the difficulty of using terms like 'IEEE 802.16' in common
speech and writing.

Fig 1: Wi-Fi and WiMAX logo

WiMAX and Wi-Fi are both wireless broadband technologies, but they differ in the
technical execution. Wi-Fi was developed to be used for mobile computing devices, such as
laptops, in LANs, but is now increasingly used for more services, including Internet and VoIP
phone access, gaming, and basic connectivity of consumer electronics such as televisions and
DVD players, or digital cameras. On the other hand WiMAX was developed as a standards-
based technology enabling the delivery of last mile wireless broadband access as an alternative to
cable and DSL

Division of Computer Science, SOE CUSAT 1

Wi-MAX Versus Wi-Fi

CHAPTER 2

WIRELESS NETWORKING
How Internet can be made available in remote places of our county with cost effective manner?

By using wireless networks

Imagine the possibility of an ambulance with high quality wireless connections to a hospital,
vital information of injured patient can be send to hospital instantly from accident sport so that
the hospital would be ready for treating the patient by the time he/she arrives there. The term
wireless networking refers to technology that enables two or more computers to communicate
using standard network protocols but without network cable.Wireless networks recognize the
radio waves and microwaves to maintain communication channel between computers

FIG 2: Wireless Network between two computers


Wi-MAX Versus Wi-Fi

Basic type of wireless networks can be classified into

 Ad hoc network (Peer to Peer): each device is equipped with wireless Cards and they
can setup a network very quickly with out any infrastructure.

 Infrastructure based network: The device communicate each other through a base
station.

2.1 Wireless Standards

IEEE 802 refers to a family of IEEE standards dealing with local area networks and
metropolitan area networks. More specifically, the IEEE 802 standards are restricted to
networks carrying variable-size packets. (By contrast, in cell-based networks data is transmitted
in short, uniformly sized units called cells. Isochronous networks, where data is transmitted as a
steady stream of octets, or groups of octets, at regular time intervals, are also out of the scope of
this standard.) The number 802 was simply the next free number IEEE could assign, through
”802” is sometimes associated with the date the first meeting was held – February 1980

Fig 3: 802 wireless standards


Wi-MAX Versus Wi-Fi

CHAPTER 3

What is Wi-Fi?

Wi-Fi is a trademark of the Wi-Fi Alliance that manufacturers may use to brand certified
products that belong to a class of wireless local area network (WLAN) devices based on the
IEEE 802.11 standards, which is by far the most widespread WLAN class today. Because of the
close relationship with its underlying standard, the term Wi-Fi is often used as a synonym for
IEEE 802.11 technology

Wi-Fi is for Wireless Fidelity, essentially a set of standards for transmitting data over a wireless
network. Wi-Fi allows you to connect to the net at broadband speeds without cables, as long as
you have the right equipment and, in most cases, a regular internet service provider and a Wi-Fi
account.

Fig 4: WLAN standard


Wi-MAX Versus Wi-Fi

USES:

1. Internet Access
A Wi-Fi enabled device such as a personal computer, video game console, mobile phone,
MP3 player or personal digital assistant can connect to the Internet when within range of a
wireless network connected to the Internet. The coverage of one or more (interconnected) access
points — called hotspots — can comprise an area as small as a few rooms or as large as many
square miles. Coverage in the larger area may depend on a group of access points with
overlapping coverage.
In addition to private use in homes and offices, Wi-Fi can provide public access at Wi-Fi
hotspots provided either free-of-charge or to subscribers to various commercial services.
Organizations and businesses - such as those running airports, hotels and restaurants - often
provide free-use hotspots to attract or assist clients.

In internet access we have

1.a City-wide Wi-Fi

In the early 2000s, many cities around the world announced plans for city-
wide Wi-Fi networks. This proved to be much more difficult than their promoters initially
envisioned with the result that most of these projects were either cancelled or placed on
indefinite hold. A few were successful, for example in 2005, Sunnyvale, California
became the first city in the United States to offer city-wide free Wi-Fi


Wi-MAX Versus Wi-Fi

1.b Campus-wide Wi-Fi

Carnegie Mellon University built the first wireless Internet network in the
world at their Pittsburgh campus in 1994, long before Wi-Fi branding originated in 1999. Most
campuses now have wireless Internet.

2. Direct Computer-to-Computer Communication

Wi-Fi also allows communications directly from one computer to another without
the involvement of an access point. This is called the ad-hoc mode of Wi-Fi
transmission.

3. Future Directions

As of 2010 Wi-Fi technology has spread widely within business and industrial
sites. In business environments, just like other environments, increasing the
number of Wi-Fi access points provides network 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

3.1 How Wi-Fi works?

Wi-Fi uses one or more Wireless Access Points (WAP) (can be compared to cell phone towers)
and clients (WiFi Adapters) (comparable to cell phones) to transfer data by the use of radio
waves. These Access points serve as base station for various wi-fi enabled equipments.


Wi-MAX Versus Wi-Fi

The access point broadcasts it’s SSID (The network name) and clients can identify it and decide
to connect. If two or more access point uses same SSID, the client will automatically connect to
the access point that has better signal strength.

The electronics on the receiver’s end are called WiFi adapters and it can be either in-built to the
device itself or can be in the form of an external device like a USB stick.

Wi-Fi networking can transfer data at a rate ranging from 2Mbps – 108 Mbps and for a distance
from several meters to several hundred meters. The signal strength depends on the distance from
access points and the type of Wi-Fi technology in use.

Figure below shows how Wi-Fi works. The description of the numbers shown in the figure helps
to understand the working of Wi-Fi.

Fig 5: How does Wi-Fi works


Wi-MAX Versus Wi-Fi

1: Wi-fi uses antennas around which wi-fi "hotspots" are created. The hotspots are outlets
equipped to receive the radiowaves that power wireless networking. Until recently, wi-fi has
been confined to more than 10,000 hot-spots in cafes, bars and airport lounges. But various
projects are under way to set up city-wide zones, where a series of antennas are installed in the
streets, on lampposts or street signs. The hotspots around them together create a much wider area
of coverage. Norwich has a mesh network which links each lamppost antenna to the next
creating a seamless wi-fi hotspot around the centre of the city.

2: The source internet connection is provided by a PC or server to which the antennas are
connected either wirelessly or via a cable.
3: Some mobile phones and personal digital assistants (PDA) now have Wi-Fi chips installed.
With mobile phones, this means conventional networks can be bypassed and inexpensive long-
distance calls made over the web (using Voice over Internet Protocol, VoIP).

4: Many laptops and handheld computers now come with built-in wi-fi connectivity; it is also
possible to add wi-fi to your computer with a special card that plugs into a port on your laptop.


Wi-MAX Versus Wi-Fi

3.2 Wi-Fi Technology Standards

 IEEE 802.11 Standards Wi-Fi

The first version of Wi-Fi standard 802.11 uses 2.4GHz spectrum to transfer data. The
operating speeds were around 1-2Mbps. This version was released in 1997.

 IEEE 802.11a (Wi-Fi a)

Released in 1999, this version of Wi-Fi uses 5GHz frequency spectrum and are capable
of providing 10Mbps speed.

 IEEE 802.11b (Wi-Fi b)

This was the modified format to tackle the issues of 802.11a version, where multiple
access points were required for stable reception. The major change was that this version uses
2.4GHz frequency spectrum. 802.11b version works at a speed of 11Mbps and was widely
accepted at the time of release.

 IEEE 802.11g (Wi-Fi g)

The most widely accepted Wi-Fi networking format of modern times. Wi-Fi g can deliver
speeds up to 54Mbps and can support many clients. This version works on 2.4GHz spectrum.
This version was released in 2003.

 IEEE 802.11n (Wi-Fi n)


Wi-MAX Versus Wi-Fi

The newest version, currently in draft can deliver speeds up to 108Mbps and has a signal
range of several hundred meters. This technology uses multiple input multiple output pipelining
and hence can use multiple antennas for better signal strength.

Standard Maximum bit Channels Frequency Radio
rate provided band techniques
802.11 2 Mbps 3 2.4 GHz FHSS or DSSS
802.11 b 11 Mbps 3 2.4 GHz DSSS
802.11 a 54 12 5 GHz OFDM
802.11 g 54 3 2.4 GHz OFDM

Table 1: IEEE 802.11 Radio Link Interfaces

3.3 Advantages of Wi-Fi

• No Wires Required – Wi-Fi technology allows you to deploy networks without the hassle
of wiring up your computers. Since Wi-Fi does not use wires, you can easily set up
wireless networks even outdoors.


Wi-MAX Versus Wi-Fi

• Wi-Fi Chipsets are Cheap – Wi-Fi adapters are now built-in with laptops; hence you
don’t need to add any extra device to receive Wi-Fi signals.

• New Wi-Fi Devices – Many new devices (Camera / Cell phones / Personal Media Players
/ Media Storage Devices …) support Wi-Fi technology. You can easily transfer files from
these devices without any wires. Some of the newer devices even provide direct internet
uploading from the device itself.

• Backward Compatibility – Wi-Fi versions working on same operating spectrum are
backward compatible. Hence if you have an old Wi-Fi device, it can work on your newest
Wi-Fi access point.

• Data Encryption – Wi-Fi supports different types of advanced encryption technologies to
securely encrypt your data. This means, you can use wifi for transferring confidential
data on a secured network.

• Wifi Hotspots – Businesses can provide Wi-Fi hotspots (Public Wi-Fi area) to increase
the customer base. Many universities, Airports and retail markets started providing public
WiFi services.

3.4 Disadvantages of Wi-Fi

• Signal Strength Limitation – As wifi uses radio waves, the signal strength is affected by
the presence of obstacles. Hence wifi works better on outdoors than indoors.

• Data Transfer Limit – According to latest Wi-Fi n draft, this technology can seamlessly
deliver speeds upto 108Mbps, but we already have better technology (Gigabit LAN) that


Wi-MAX Versus Wi-Fi

can deliver speeds up to 1000 Mbps. Hence Wi-Fi technology in present state are not
suitable for fast connectivity needs like network gaming.

• Uses Shared Frequency Spectrum – The operating frequency of 2.4GHz is used by
Bluetooth devices, Microwave ovens, Cordless Phones and many other home appliances.
Hence there is a chance of interference or network crowding for the Wi-Fi signals, which
can adversely affect the quality of signal.

• Un-Secured WAP(Wireless Access Point) can result in malicious usage. Even though
many routers / access points comes with security features, they are seldom used. The
result is that anyone with a Wi-Fi adapter with in the range can use your connection
without your knowledge.


Wi-MAX Versus Wi-Fi

CHAPTER 4

What is WiMAX?

WiMAX is a digital wireless data communication system that can deliver high-speed broadband
services up to a large distance of 50KMs.The name WiMAX was created by WiMAX forum, the
consortium promoting this standard. The term WiMAX is derived from the phrase Worldwide
Interoperability for Microwave Access.

The WiMAX system was designed to popularize broadband access the way cell phones have
done to our telephone communication system. WiMAX may replace the old form of broadband
access through landlines, DSL and cable in future.

The WiMAX system can be considered as an efficient alternative to Wi-Fi, where the un-
avoidable limitation was the distance of coverage. WiMAX solves this problem by using higher
frequency range to deliver more data to a larger distance.

Fig 6: WMAN standard


Wi-MAX Versus Wi-Fi

USES:

The bandwidth and range of WiMAX make it suitable for the following potential applications:

• Providing portable mobile broadband connectivity across cities and countries through a
variety of devices.

• Providing a wireless alternative to cable and DSL for "last mile" broadband access.
• Providing data, telecommunications (VoIP) and IPTV services (triple play).
• Providing a source of Internet connectivity as part of a business continuity plan.
• Providing a network to facilitate machine to machine communications, such as for Smart
Metering

4.1 How WiMAX Works?

WiMAX, just like Wi-Fi uses radio waves to transfer data. The important difference is that
WiMAX uses two spectrums of frequencies to provide two kinds of wireless broadband access
services. (Mobile WiMAX & Fixed WiMAX)

The WiMAX system has two parts; one is the WiMAX tower (similar to a cell phone tower) and
a receiver. The receiver can be of two types depending on the device. It can be an embedded
device just like our wi-Fi receivers or it can be advanced hardware equipment with dedicated
antennae.

The WiMAX tower connects to internet through regular mediums of connectivity like fibre optic
cable or T1 lines. It can also connect with other WiMAX towers using radio link.


Wi-MAX Versus Wi-Fi

This additional line-of-sight connectivity is the biggest advantage of WiMAX. Technically, this
is called the backhaul system. Thus by installing multiple towers, WiMAX can easily provide
broadband access to large number of people.

Fig 7: How WiMAX works


Wi-MAX Versus Wi-Fi

4.2 BACKHAUL

Backhaul is actually a connection system from the Access Point (AP) back to the provider and
to the connection from the provider to the network. A backhaul can set out any technology and
media provided; it connects the system to the backbone. In most of the WiMAX deployments
circumstances, it is also possible to connect several base stations with one another by use of
high speed backhaul microware links. This would also allow for roaming by a WiMAX
subscriber from one base station coverage area to another, similar to roaming enabled by
cellular phone.

Fig 8: A WiMAX TOWER


Wi-MAX Versus Wi-Fi

4.3 Types of WiMAX

WiMAX delivers broadband access in two ways depending on the operational frequencies.

• Fixed WiMAX
• Mobile WiMAX

o Fixed WiMAX

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

In this form, WiMAX tower works more like an efficient & powerful Wi-Fi access point. The
frequency range of operation is 2GHz – 11GHz, almost similar to Wi-Fi frequencies.

In this mode of operation, the data transfer occurs between WiMAX tower and the internal
mobile receivers. As the frequency of operation is low, there is a limitation in area of coverage.
According to theory, this type of WiMAX can only deliver up to 6-7 KMs.

The same effect can be analogized to cell phone tower system. That is the same reason, why we
need more number of towers for wide area coverage.

o Mobile WiMAX

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".


Wi-MAX Versus Wi-Fi

In this form, the receiver requires dedicated antennae properly installed in the line-of-sight of
WiMAX tower. These types of connections are stronger and stable as it uses 66GHz frequency
spectrum to carry more data. This mode of operation can deliver broadband services to about
50KM radius.

Table 2: Summary of 802.16 Radio Link


Wi-MAX Versus Wi-Fi

4.4 Advantages of WiMAX

• Large Area of Coverage: As WiMAX can deliver high-speed internet to large distance, it
is very well suited to provide broadband access to remote areas of the world.
• Scalability: As earlier mentioned, by using backhaul feature of WiMAX, you can set up
large number of WiMAX towers in matter of days as opposed to wiring that requires
proper planning and heavy labor.
• In Built QoS: Quality of Service mechanisms in WiMAX allows mission-critical services
to run smoothly even if there is lack of resources. This way, mission critical services are
allowed to run at full priority when everything is busy.
• Multi-User Connectivity: A single WiMAX tower can connect to 100 client receivers.
These clients can of different modes of operation

4.5 Disadvantage of WiMAX

• Specialized Equipment Required: For utilizing full functionality of WiMAX, you need
specialized hardware with dedicated antennae.
• Limited Date Rate: When compared to other modes of broadband connectivity, for
example, fibre optic cables and satellite internet, WiMAX is still slow.
• Bandwidth Shared Among Users: WiMAX’s another drawback is that it distributes the
bandwidth among users. This means, you will experience slow down when there are
more uses in the base.
• Speed Decrease over Large Distance: Because of bit rate errors happening at large
distance, WiMAX system is forced to use lower bit rates at these distances. This means
less data transfer rate.


Wi-MAX Versus Wi-Fi

• Interference May Affect Connectivity: As the WiMAX uses radio waves, it is susceptible
to interference caused by other equipments.
• Rain can affect Connectivity: As fixed WiMAX requires line-of-sight radio link, heavy
rain can disrupt the entire link.


Wi-MAX Versus Wi-Fi

CHAPTER 5

WiMAX versus Wi-Fi

Comparing WiMAX to Wi-Fi is akin to comparing apples to oranges. Initially it’s easy to see
why the comparison would exist, as most people think WiMAX is merely a more robust version
of Wi-Fi. Indeed they are both wireless broadband technologies, but they differ in the technical
execution and ultimately their business case is very different. In addition to the technical
differences that exist, the marketplace difference is that equipment is more or less non-existent
for WiMAX and certainly not geared towards a residential environment with very high pricing to
be expected. It will take at least 2 years to see equipment of mass market uptake pricing.

WiMAX will not be commercially available until the second half of 2005, and even then at a
very controlled level. This is primarily due to standardization issues. In fact, it won’t be until
2006 that a robust production and implementation will happen due to the ramp-up period for
manufacturers. This is certainly one challenge to the widespread adoption of WiMAX.
Additionally, WiMAX will have issues of pricing, and will remain far more expensive than Wi-
Fi. WiMAX will be primarily adopted by businesses to replace or displace DSL, and offices that
want to cover a lot of territory without entering the world of endless repeaters that are necessary
with the 802.11 technologies. It will take some time (2 years) for WiMAX to significantly reduce
its price-point for residential uptake. WiMAX will not displace WiFi in the home because WiFi
is advancing in terms of speed and technology. Each year brings a new variant to the 802.11 area
with various improvements.

Additionally, for commercial deployment, frequency allocation will be an issue. With the three
dominant communications players controlling the best frequencies, it will be hard to get the type
of traction needed with the remaining companies operating in the frequencies available. WiMAX
will become extremely robust and displace WiFi as the deployment of choice for commercial
deployments, but that won’t even begin until the end of 2006. Based upon the number of public
hotspots already deployed, WiMAX will not be chosen to replace those as they are up and


Wi-MAX Versus Wi-Fi

running adequately and personnel involved understand how to work with the technology. The
business case does not exist at the hotspot level. Where it may exist is for wider free use
deployments such as city deployments (free ones) and other government sponsored or carrier
sponsored (with ultra inexpensive pricing for consumers) deployments. If this happens then its
not only WiFi that will be displaced, but cable and DSL will also lose a percentage of their
subscriber base. What will cause the displacement is the consumer’s proven desire for a bundled
package.

5.1 Uses of Wi-Fi vs. the uses of WiMAX

Wi-Fi is mostly used to provide a Wi-Fi enabled device such as a computer, cell phone or
PDA an Internet/LAN connection when in proximity of an access point. Wi-Fi can also be used
to create a mesh network. Wi-Fi also allows connectivity in peer-to-peer mode, which enables
devices to connect directly with each other.

WiMAX on the other hand with its higher bandwidth and longer reach is planned to be
used for connecting Wi-Fi hotspots with each other and to other parts of the Internet, providing a
wireless alternative to cable and DSL for last mile (last km) broadband access, providing high-
speed mobile data and telecommunications services (4G).

5.2 Capacity of Wi-Fi vs. WiMAX

Both the Wi-Fi and the WiMAX connectivity are dependent on the distance of two
connection points (antennas). Keeping this in mind we can see that when using Wi-Fi with the
IEEE 802.11g standard, which is the most common standard used on today’s equipment, the data
rate is around 54 Mbit/s and the range indoors are around 30 meters. This range and data rate is
changed with the conditions of the area used and the line of sight of devices used.


Wi-MAX Versus Wi-Fi

WiMAX will deliver 70 Mbit/s, 112 kilometers in theory. But these numbers will change
according to conditions, expected values are 10Mbit/s in a 2 KM area.

5.3 Technical differences of the two standards

5.3.1 Media Access Controller (MAC) Layer
In Wi-Fi MAC uses contention access — all subscriber stations that wish to pass data
through a wireless access point (AP) are competing for the AP's attention on a random interrupt
basis. This can cause subscriber stations distant from the AP to be repeatedly interrupted by
closer stations, greatly reducing their throughput. This makes services such as Voice over IP
(VoIP) or IPTV, which depend on an essentially constant Quality of Service (QoS) depending on
data rate and interruptibility, difficult to maintain for more than a few simultaneous users.

In contrast, the 802.16 MAC uses a scheduling algorithm for which the subscriber station
need compete once (for initial entry into the network). After that it is allocated an access slot by
the base station. The time slot can enlarge and contract, but remains assigned to the subscriber
station which means that other subscribers cannot use it. The 802.16 scheduling algorithm is
stable under overload and over-subscription (unlike 802.11). It can also be more bandwidth
efficient. The scheduling algorithm also allows the base station to control QoS parameters by
balancing the time-slot assignments among the application needs of the subscriber stations.

5.3.2 Physical layer
In Wi-Fi except for 802.11a, which operates at 5 GHz, Wi-Fi uses the spectrum near 2.4
GHz, which is standardized and unlicensed by international agreement, although the exact
frequency allocations vary slightly in different parts of the world, as does maximum permitted
power. However, channel numbers are standardized by frequency throughout the world, so
authorized frequencies can be identified by channel numbers. The frequencies for 802.11 b/g
span 2.400 GHz to 2.487 GHz. Each channel is 22 MHz wide yet there is a 5 MHz step to the
next higher channel. The maximum number of available channels for Wi-Fi enabled devices is
13 for Europe, 11 for North America and 14 for Japan.


Wi-MAX Versus Wi-Fi

Whereas in WiMAX, the original WiMAX standard (IEEE 802.16) specified WiMAX for
the 10 to 66 GHz range. 802.16a, updated in 2004 to 802.16-2004 (also known as 802.16d),
added specification for the 2 to 11 GHz range. 802.16d (also known as "fixed WiMAX") was
updated to 802.16e in 2005 (known as "mobile WiMAX"). and uses scalable orthogonal
frequency-division multiplexing (OFDM) as opposed to the OFDM version with 256 sub-carriers
used in 802.16d. More advanced versions including 802.16e also bring Multiple Antenna
Support through Multiple-input, multiple-output communications. This brings potential benefits
in terms of coverage, self installation, power consumption, frequency re-use and bandwidth
efficiency. 802.16e also adds a capability for full mobility support. The WiMAX certification
allows vendors with 802.16d products to sell their equipment as WiMAX certified, thus ensuring
a level of interoperability with other certified products, as long as they fit the same profile.

Most interest will probably be in the 802.16d and .16e standards, since the lower
frequencies suffer less from inherent signal attenuation and therefore give improved range and
in-building penetration. Already today, a number of networks throughout the World are in
commercial operation using certified WiMAX equipment compliant with the 802.16d standard.

5.3.3 Network layer

Both standards are designed to be used with the first and the second layers of the OSI
model. Both the standards can be used with a variety of different network layers, including IP.

Table 3: Mobile Standards Compared


Wi-MAX Versus Wi-Fi

In general we can say, even though both WiMAX and Wi-Fi works on radio waves, there are
differences in their operations and functionalities.

WiMAX Wi-Fi

(802.16) (802.11)

Range long distance system, high- short-range system,
speed broadband access to broadband access to several
several KMs hundred feet

Data Rate 70Mbps 54Mbps

Scalability highly scalable Not scalable

Local Network cannot use it for your own work for private networks
private network

Spectrum Licensing requires spectrum licensing does not require such a
license

Table 4: the comparison of WiMAX and Wi-Fi


Wi-MAX Versus Wi-Fi

CHAPTER 6

Conclusion

Even though WiFi technology has many disadvantages, properly configured WAPs will give
you the best wireless connectivity you can get. Latest developments show that WiFi would be
embedded in to most of the consumer devices, thus enabling us to wirelessly interact and there
by improve the productivity and entertainment experience.

As WiMAX delivers high-speed internet through wireless medium, the cost of implementing
broadband access to remote parts of world are very low. Because of the same reason, we believe
WiMAX have huge potential to become the world’s popular broadband access method in near
future.

Wi-Fi and WiMAX are complementary. WiMAX network operators typically provide a WiMAX
Subscriber Unit which connects to the metropolitan WiMAX network and provides Wi-Fi within
the home or business for local devices (e.g., Laptops, Wi-Fi Handsets, smart phones ) for
connectivity. This enables the user to place the WiMAX Subscriber Unit in the best reception
area (such as a window), and still be able to use the WiMAX network from any place within
their residence.


Wi-MAX Versus Wi-Fi

CHAPTER 7

REFERENCES

 Stallings, William, Data and Computer Communications, Pearson-Prentice Hall, 7th Ed.,
USA, 2004.
 http://en.wikipedia.org/wiki/Wimax
 http://en.wikipedia.org/wiki/Wifi
 http://www.voip-news.com/news/features/wifi-vs-wimax-050806/
 http://www.mobilein.com/WiFi_vs_WiMax.htm
 http://en.wikipedia.org/wiki/IEEE_802.11
 http://en.wikipedia.org/wiki/IEEE_802.16
 http://en.wikipedia.org/wiki/OSI_model
 http://changelog.ca/topic/WiMax
 http://www.cisco.com/en/US/netsol/ns341/ns396/ns177/networking_solutions_white_pap
er0900aecd801aa448.shtml
 http://www.tutorialsweb.com/wimax/wimax.htm


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