WiMAX
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28-01-2009, 02:04 PM


ABSTRACT

In recent years, Broadband technology has rapidly become an established, global commodity required by a high percentage of the population. The demand has risen rapidly, with a worldwide installed base of 57 million lines in 2002 rising to an estimated 80 million lines by the end of 2003. This healthy growth curve is expected to continue steadily over the next few years and reach the 200 million mark by 2006. DSL operators, who initially focused their deployments in densely-populated urban and metropolitan areas, are now challenged to provide broadband services in suburban and rural areas where new markets are quickly taking root. Governments are prioritizing broadband as a key political objective for all citizens to overcome the ?broadband gap? also known as ?digital divide?.
Wireless DSL (WDSL) offers an effective, complementary solution to wireline DSL, allowing DSL operators to provide broadband service to additional areas and populations that would otherwise find themselves outside the broadband loop. Government regulatory bodies are realizing the inherent worth in wireless technologies as a means for solving digital-divide challenges in the last mile and have accordingly initiated a deregulation process in recent years for both licensed and unlicensed bands to support this application. Recent technological advancements and the formation of a global standard and interoperability forum - WiMAX, set the stage for WDSL to take a significant role in the broadband market. Revenues from services delivered via Broadband Wireless Access have already reached $323 million and are expected to jump to $1.75 billion.

INTRODUCTION
There are several ways to get a fast Internet connection to the middle of nowhere. Until not too long ago, the only answer would have been ?cable? ? that is, laying lines. Cable TV companies, who would be the ones to do this, had been weighing the costs and benefits. However this would have taken years for the investment to pay off. So while cable companies might be leading the market for broadband access to most people (of the 41% of Americans who have high-speed Internet access, almost two-thirds get it from their cable company), they don?t do as well to rural areas. And governments that try to require cable companies to lay the wires find themselves battling to force the companies to take new customers.
Would DSL be a means of achieving this requisite of broadband and bridging the digital divide?
The lines are already there, but the equipment wasn?t always the latest and greatest, even then. Sending voice was not a matter of big concern, but upgrading the system to handle DSL would mean upgrading the central offices that would have to handle the data coming from all those farms.
The most rattling affair is that there are plenty of places in cities that can?t handle DSL, let alone the country side. Despite this, we?ll still read about new project and implimentations to lay cable out to smaller communities, either by phone companies, cable companies, or someone else. Is this a waste of money? Probably because cables are on their way out. Another way to get broadband to rural communities is the way many folks get their TV: satellite, which offers download speeds of about 500 Kbps ?faster than a modem, but at best half as fast as DSL ? through a satellite dish. But you really, really have to want it. The system costs $600 to start, then $60 a month by the services provided by DIRECWAY in the US.
There are other wireless ways to get broadband access.
MCI (?Microwave Communications Inc.?) was originally formed to compete with AT & T by using microwave towers to transmit voice signals across the US. Unlike a radio (or a Wi-Fi connection), those towers send the signal in a straight line ?unidirectional instead of omni directional. That?s sometimes called fixed wireless or point-to-point wireless. One popular standard for this is called LMDS: local multipoint distribution system. Two buildings up to several miles apart would have microwave antennas pointing at each other. One (in, say, the urban area) would be connected to the Internet in the usual way, via some kind of wire; the other (in the rural area you want to connect) would send and receive data over the microwave link, and then be connected to homes and farms via cables. Those cables would be much shorter and less expensive, with the bulk of the transmission being done through the ether.

WiMAX:
WiMax delivers broadband to a large area via towers, just like cell phones. This enables your laptop to have high-speed access in any of the hot spots. Instead of yet another cable coming to your home, there would be yet another antenna on the cell-phone tower. This is definitely a point towards broadband service in rural areas. First get the signal to the area, either with a single cable (instead of one to each user) or via a point-to-point wireless system. Then put up a tower or two, and the whole area is online. This saves the trouble of digging lots of trenches, or of putting up wires that are prone to storm damage.
However there is one promising technology that still uses cables to deliver a broadband signal to, well, wherever. It doesn?t require laying any new wires (like cable Internet), and it doesn?t require overhauling a lot of existing systems (like DSL).It?s BPL: (broadband over power lines). As the name suggests, it piggybacks a high speed data signal on those ubiquitous power lines. Those aren?t the low-voltage ones that come to your house, but the medium-voltages ones that travel from neighborhood to neighborhood. The signal, like those power lines, can travel a long way thanks to ?regenerators? that not only pass the data along, but clean the signal so it doesn?t degrade over distance. That means the signal can travel as long as the lines do. Those regenerators can also include Wi-Fi antennas, so if you space them properly they can be placed near homes and farms and whatnot. You can also connect a cable to one to take the signal to the door if you don?t feel like going the W-Fi way.
However there have been certain hiccups in the case of BPL. Unlike some early (and ongoing) attempts to do Internet through power lines, BPL doesn?t go into individual homes. That?s because in order to do so, the signal would have to make its way through a transformer and through a circuit-breaker box, both of which play havoc with it. The result is that the data get through, but much more slowly than leaving the power line before the transformer.
Combine BPL with Wi-Fi, WiMAX, or even (short) cables, and we have an inexpensive way to get the power of the Internet down on the farm using the power of power.
WiMAX is revolutionizing the broadband wireless world, enabling the formation of a global mass-market wireless industry. Putting the WiMAX revolution in the bigger context of the broadband industry, this paper portrays the recent acceleration stage of the Broadband Wireless Access market, determined by the need for broadband connectivity.
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14-02-2009, 11:43 PM

WIMAX: Worldwide Interoperability for Microwave access
What is WiMAX?

Think about how you access the Internet today. There are basically three different options:

* Broadband access - In your home, you have either a DSL or cable modem. At the office, your company may be using a T1 or a T3 line.
* WiFi access - In your home, you may have set up a WiFi router that lets you surf the Web while you lounge with your laptop. On the road, you can find WiFi hot spots in restaurants, hotels, coffee shops.
* Dial-up access - If you are still using dial-up, chances are that either broadband access is not available, or broadband access is too expensive.

The main problems with broadband access are that it is pretty expensive and it doesn't reach all areas and with WiFi access is that hot spots are very small, so coverage is sparse. What if there was a new technology that solved all of these problems? This new technology would provide:

* The high speed of broadband service.
* Wireless rather than wired access, so it would be a lot less expensive than cable or DSL and much easier to extend to suburban and rural areas.
* Broad coverage like the cell phone network instead of small WiFi hotspots.

This system is actually coming into being right now, and it is called WiMAX. WiMAX is short for Worldwide Interoperability for Microwave Access, and it also goes by the IEEE name 802.16.

WiMAX has the potential to do to broadband Internet access what cell phones have done to phone access. WiMAX could replace cable and DSL services, providing universal Internet access just about anywhere you go. WiMAX will also be as painless as WiFi -- turning your computer on will automatically connect you to the closest available WiMAX antenna.

WiMax Components:
The core components of a WiMax system are the subscriber station (SS) otherwise known as the CPE and the base station (BS). A BS and one or more SSs can form a cell with a point-to-multipoint (P2MP) structure. BS controls activity within the cell, including access to the medium by SS, allocations to achieve quality of service (QoS) and admission to the network based on network security mechanisms.
An 802.16-based system often uses fixed antenna at the subscriber station site. The antenna is mounted to the roof or an eave. Provisions such as adaptive-antenna systems (AAS) and sub-channelization are also supported optionally by the standard for enhanced link budget required for in-door installation. IEEE 802.16e sub-committee is currently working on extension to the standard required for mobility and support for the power limited SS terminals.
A BS typically uses either sectored or omni-directional antennas. A fixed SS typically uses directional antenna while mobile or portable SS usually uses an omni-directional antenna. Multiple BSes can be configured to form a cellular wireless network. When OFDM is used, the cell radius can ideally reach up to 30 miles. Practical cell sizes usually have a small radius of around 5 miles or less. The 802.16 standard also can be used in a point-to-point (P2P) or mesh topology, using pairs of directional antennas. This can be used to increase the effective range of the system relative to what can be achieved in P2MP mode.

The WiMAX Scenario:
Here's what would happen if you got WiMAX. An Internet service provider sets up a WiMAX base station 10 miles from your home. You would buy a WiMAX-enabled computer (some of them should be on store shelves in 2005) or upgrade your old computer to add WiMAX capability. You would receive a special encryption code that would give you access to the base station. The base station would beam data from the Internet to your computer (at speeds potentially higher than today's cable modems), for which you would pay the provider a monthly fee. The cost for this service could be much lower than current high-speed Internet-subscription fees because the provider never had to run cables.

WIMAX ARCHITECTURE

A wireless MAN, based on the WIMAX air interface standard is configured in much the same way as a traditional cellular network with strategically located base stations using a point-to-multipoint architecture to deliver services over a radius up to several kilometers depending on frequency, transmit power and receiver sensitivity. In areas with high population densities the range will generally be capacity limited rather than range limited due to limitation in the amount of available spectrum. The base stations are typically backhauled to the core network by means of fiber or point-to-point microwave links to available fiber nodes or via leased lines from an incumbent wire-line operator. The range and non line of sight (NLOS) capability makes the technology equally attractive and cost-effective in a wide variety of environments. The technology was envisioned from the beginning as a means to provide wireless last mile broadband access in the Metropolitan Area Network (MAN) with performance and services comparable to or better than traditional DSL, Cable or T1/E1 leased line services.

2.1 The WIMAX System:

A WIMAX system consists of two parts:

A Base Station (BS) is mounted on a building or a tower that communicates on a point to multi-point basis with the Subscriber Units. It can provide coverage to a very large area - as big as 3,000 square miles (~8,000 square km). There are two likely types of base stations:

1] A Standard Base Station with:

· Basic WIMAX implementations (mandatory capabilities)

· Standard RF output power for a lower cost base station (vendor specific)

2] A Fully Featured Base Station with:

· Higher RF output power than standard base station (vendor specific)

· Sub-channeling.

· Automatic Repeat Request(ARQ)

A Subscriber Unit (SU) installed at the customer premises also called as Customer Premise Equipment, enables the customer data connection to the Access Unit (AU). CPEâ„¢s can be of different types (depending on end users):

· A modem attached to an external antenna

· A modem with an indoor antenna

· Integrated antenna.

2.2 How WIMAX Works:

A WIMAX Base Station (BS) can connect directly to the Internet using a high-bandwidth, wired connection (for example, a T3 line). It can also connect to another WIMAX BS using a line-of-sight, microwave link. This connection, often referred to as a backhaul, along with the ability of a single BS to cover up to 3,000 square miles, is what allows WIMAX to provide coverage to remote rural areas.

Fig 1: WIMAX system

WIMAX can actually provide two forms of services:

* Non Line Of Sight (NLOS): It is a WiFi sort of service where a small antenna on the CPE connects to the BS. In this mode WIMAX uses a lower frequency range (2GHz-11GHz).The signal reaches the receiver through reflections, scattering and diffractions. These lower wavelength transmissions are not easily disrupted by physical obstructions.
* Line Of Sight (LOS): In this a fixed dish antenna points straight at the WIMAX BS from the rooftop or pole. It requires most of the first Fresnel Zone to be free of any obstructions which in turn depends upon the operating frequency and the distance. LOS transmissions use high frequencies reaching a possible of 66GHZ.

LOS connection is stronger and more stable and it is able to send a lot of data with fewer errors. However there are several advantages of NLOS deployments. For large-scale contiguous cellular deployments, where frequency re-use is critical, lowering the antenna is advantageous to reduce the co channel interference between adjacent cell sites. This often forces the base stations to operate in NLOS conditions. LOS systems cannot reduce antenna heights because doing so would impact the required direct view path from the CPE to the Base Station. NLOS technology also reduces installation expenses by making under-the-eaves CPE installation a reality.

How WiMAX Works?


WiMAX transmitting tower

In practical terms, WiMAX would operate similar to WiFi but at higher speeds, over greater distances and for a greater number of users. WiMAX could potentially erase the suburban and rural blackout areas that currently have no broadband Internet access because phone and cable companies have not yet run the necessary wires to those remote locations.

A WiMAX system consists of two parts:

* A WiMAX tower, similar in concept to a cell-phone tower - A single WiMAX tower can provide coverage to a very large area -- as big as 3,000 square miles (~8,000 square km).
* A WiMAX receiver - The receiver and antenna could be a small box or PCMCIA card, or they could be built into a laptop the way WiFi access is today.

A WiMAX tower station can connect directly to the Internet using a high-bandwidth, wired connection (for example, a T3 line). It can also connect to another WiMAX tower using a line-of-sight, microwave link. This connection to a second tower (often referred to as a backhaul), along with the ability of a single tower to cover up to 3,000 square miles, is what allows WiMAX to provide coverage to remote rural areas.

Some technologies like Chipsets are currently custom-built for each broadband wireless access vendor, adding time and cost to the process. Its equivalent or competitor in Europe is HIPERMAN. But WiMax has the ability to overcome them.

What this points out is that WiMAX actually can provide two forms of wireless service:

* There is the non-line-of-sight, WiFi sort of service, where a small antenna on your computer connects to the tower. In this mode, WiMAX uses a lower frequency range -- 2 GHz to 11 GHz (similar to WiFi). Lower-wavelength transmissions are not as easily disrupted by physical obstructions -- they are better able to diffract, or bend, around obstacles.
* There is line-of-sight service, where a fixed dish antenna points straight at the WiMAX tower from a rooftop or pole. The line-of-sight connection is stronger and more stable, so it's able to send a lot of data with fewer errors. Line-of-sight transmissions use higher frequencies, with ranges reaching a possible 66 GHz. At higher frequencies, there is less interference and lots more bandwidth.

WiFi-style access will be limited to a 4 to 6 mile radius (perhaps 25 square miles or 65 square km of coverage, which is similar in range to a cell-phone zone). Through the stronger line-of-sight antennas, the WiMAX transmitting station would send data to WiMAX-enabled computers or routers set up within the transmitter's 30 mile radius (2,800 square miles or 9,300 square km of coverage). This is what allows WiMAX to achieve its maximum range.

WiMAX operates on the same general principles as WiFi -- it sends data from one computer to another via radio signals. A computer (either a desktop or a laptop) equipped with WiMAX would receive data from the WiMAX transmitting station, probably using encrypted data keys to prevent unauthorized users from stealing access.

The fastest WiFi connection can transmit up to 54 Mbits/sec under optimal conditions. WiMAX should be able to handle up to 70 Mbits/sec. Even once that 70 Mbits is split up between several dozen businesses or a few hundred home users, it will provide at least the equivalent of cable-modem transfer rates to each user.

The biggest difference between the WiFi and WiMax isn't speed; it's

distance. WiMAX outdistances WiFi by miles. WiFi's range is about 100 feet (30

m). WiMAX will blanket a radius of 30 miles (50 km) with wireless access. The

increased range is due to the frequencies used and the power of the transmitter. Of course, at that distance, terrain, weather and large buildings will act to reduce the maximum range in some circumstances, but the potential is there to cover

FUTURE OF WIMAX

The IEEE 802.16 standard body members are working toward incremental evolution, from fixed operation to portability and mobility. The IEEE 802.16e amendment will amend the base specification to enable not just fixed, but also portable and mobile operation. IEEE 802.16f and IEEE 802.16g task groups are addressing the management interfaces for fixed and mobile operation. Clients will be able to hand-off between 802.16 base stations, enabling users to roam between service areas. In a fully mobile scenario users may be moving while simultaneously engaging in a broadband data access or multimedia streaming session. All of these improvements will help make WIMAX an even better Internet access solution for growing economies like that of India.

Fig 7.1: Future of WIMAX

Technical advantages:

Ø WiMAX does not conflict with WiFi but actually complements it. WiMAX is a wireless metropolitan area network (MAN) technology that will connect IEEE 802.11 (WiFi) hotspots to the Internet and provide a wireless extension to cable and DSL for last mile (last km) broadband access. IEEE 802.16 provides up to 50 km (31 miles) of linear service area range and allows users connectivity without a direct line of sight to a base station.

Ø WiMAX technology theoretically supports coverage radius of 30 miles and a data rate of up to 75 Mbps, while WiFi currently supports a much shorter radius and lower data rates.

Ø WiMAX technology has the potential to enable service carriers to converge the all-IP-based network for triple-play services such as data, voice, and video.

Ø WiMAX will provide fixed, nomadic, portable and, eventually, mobile wireless broadband connectivity without the need for direct line-of-sight connection between a base station and a subscriber station.

Ø No FCC radio licensing is required.

An important aspect of the IEEE 802.16 is that it defines a MAC layer that supports multiple physical layer (PHY) specifications. This is crucial to allow equipment makers to differentiate their offerings.

Even if WiMax has the great advantages over the other technologies, it has to face some of the disadvantages.

Disadvantages:

· Line-of-sight (LOS) is required for long distance (5-30 mile) connections.

· Heavy rains can disrupt the service.

· Other wireless electronics in the vicinity can interfere with the WiMax connection and cause a reduction in data throughput or even a total disconnect. On the WiLAN side, security has been a major concern, though this has been addressed through developments in encryption technology and authentication systems. A typical access point covers an area 300 feet in diameter, but this distance can be impacted by structures within the building such as walls, furnishings etc.
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26-03-2009, 10:44 PM

can u send me the full report of this
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28-03-2009, 04:39 AM

See The Downloading Links To Get WIMAX Seminar
dspace.cusat.acdspace/bitstream/123456789/2151/1/WIMAX.pdf
athena.nitc.acreport/2005/studtheses/theses/2005/semi/Y1033f.pdf


INTRODUCTION
Broadband Wireless Access (BWA) has been serving enterprises and operators for
years, to the great satisfaction of its users. However, the new IP-based standard
developed by the IEEE 802.16 is likely to accelerate adoption of the technology. It
will expand the scope of usage thanks to: the possibility of operating in licensed and
unlicensed frequency bands, unique performance under Non-Line-of-Sight (NLOS)
conditions, Quality of Service (QoS) awareness, extension to nomadicity, and more.
In parallel, the WiMAX forum, backed by industry leaders, will encourage the
widespread adoption of broadband wireless access by establishing a brand forthe
technology and pushing interoperability between products.
The purpose of this White Paper is to highlight and assess the value of WiMAX as
the right solution to:
¢ extend the currently limited coverage of public WLAN (hotspots) to citywide
coverage (hot zones)
- the same technology being usable at home and on the move,
¢ blanket metropolitan areas for mobile data-centric service delivery,
¢ offer fixed broadband access in urban and suburban areas where copper quality is
poor or unbundling difficult,
¢ bridge the digital divide in low-density areas where technical and economic factors
make broadband deployment very challenging. In addition to these uses, this paper
will highlight other potential applications, such as telephony or an effective point-to
multipoint backhauling solution for operators or enterprises. Page 9

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Division of Computer Engineering 2
CHAPTER 2
WHAT IS WIMAX?
WiMAX is a standards-based technology enabling the delivery of last mile wireless
broadband access as an alternative to wired broadband like cable and DSL. WiMAX
provides fixed , nomadic, portable and, soon, mobile wireless broadband
connectivity without the need for direct line-of-sight with a base station. In a typical
cell radius deployment of three to ten kilometers, WiMAX Forum Certified„¢
systems can be expected to deliver capacity of up to 40 Mbps per channel, for fixed
and portable access applications.
This is enough bandwidth to simultaneously support hundreds of businesses with T-1
speed connectivity and thousands of residences with DSL speed connectivity. Mobile
network deployments are expected to provide up to 15 Mbps of capacity within a
typical cell radius deployment of up to three kilometers. It is expected that WiMAX
technology will be incorporated in notebook computers and PDAs by 2007, allowing
for urban areas and cities to become "metro zones" for portable outdoor broadband
wireless access.
USES:
The bandwidth and range of WiMAX make it suitable for the following potential
applications:
¢
Connecting Wi-Fi hotspots with other parts of the Int
¢
Providing a wireless alternative to cable and DSL for "last mile broadband
access.
¢
Providing data and telecommunications services. Page 10

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Division of Computer Engineering 3
¢
Providing a source of Internet connectivity as part of a business continuity
plan. That is, if a business has a fixed and a wireless Internet connection, especially
from unrelated providers, they are unlikely to be affected by the same service
outage. Page 11

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2.1 Standards Associated With Wimax
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, though 802 is sometimes
associated with the date the first meeting was held ” February 1980.
IEEE 802.16 :
The IEEE 802.16 Working Group on Broadband Wireless
Access Standards, which was established by IEEE Standards Board in 1999, aims
to prepare formal specifications for the global deployment of broadband Wireless
Metropolitan Area Networks. The Workgroup is a unit of the IEEE 802 LAN/MAN

Division of Computer Engineering 4 Page 12

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Standards Committee. A related future technology Mobile Broadband Wireless
Access (MBWA) is under development in IEEE 802.20.
Although the 802.16 family of standards is officially
called Wireless MAN, it has been dubbed WiMAX (from "Worldwide
Interoperability for Microwave Access") by an industry group called the WiMAX
Forum. The mission of the Forum is to promote and certify compatibility and
interoperability of broadband wireless products.
2.2Types of 802.16
¢
In January 2003, the IEEE approved 802.16a as an amendment to IEEE
802.16-2001, defining (Near) Line-Of- Sight capability.
¢ In July 2004, IEEE 802.16REVd, now published under the name IEEE
802.16-2004,introduces support for indoor CPE (NLOS) through additional
radio capabilities such as antenna beam forming and OFDM sub-channeling.
¢ Early 2005, an IEEE 802.16e variant will introduce support for mobility.

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See Figure 2.2 for the applications associated with each of these standards The
WiMAX Forum intends to do for 802.16 what the Wi-Fi Alliance did for 802.11:
¢ harmonize standards and certify interoperability between equipment from
different vendors. Standardized interoperable solutions will result in mass
mass volume and bring down cost
¢ promote and establish a brand for the technology
WiMAX, the reality beyond the hype
As mentioned above, WiMAX can offer very high data rates and extended coverage.
However,
¢75 Mbit/s capacity for the base station is achievable with a 20 MHz channel in
bestpropagation conditions. But regulators will often allow only smaller channels
(10 MHz orless) reducing the maximum bandwidth.
¢ Even though 50 km is achievable under optimal conditions and with a reduced data
rate (a few Mbit/s), the typical coverage will be around 5 km with indoor CPE
(NLOS) and around 15 km with a CPE connected to an external antenna(LOS). Page 14

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Division of Computer Engineering 7
CHAPTER 3
WHY WIMAX?
WiMAX stands for wireless interoperatibility for microwave access. WiMAX is
expected to do more for Metropolitan Area Networks (MANs) and what Wi-Fi has
done for local area networks (LANs)? WiMAX is not project and implimentationed to replace Wi-Fi, but
to complement it by connecting Wi-Fi networks to each other or the Internet through
high-speed wireless links. You can therefore use WiMAX technology to extend the
power and range of Wi-Fi and cellular networks. However, in developing countries,
WiMAX may become the only wireless technology because Wi-Fi and cellular have
not penetrated areas that can be reached with WiMAX technology.
Range
The wide range of the WiMAX technology depends on the height of the antennas, if
they are installed at the suitable position from where there is no barrier between the
transmitter and receiver, and then we can get better range and service from it. Even
though the frequency for operation of WiMAX is not definite, the most likely band
at 3.5GHz is higher in frequency than the 3G bands at around 2.1 GHz. Range will,
as a result, be lower, perhaps somewhere between 50% and 75% of the range of 3G.
WiMAX can therefore support 30 to 50 kilometres distance with Line-of-Sight
(LOS) links. As far as Non-line-of-sight (NLOS) links in concerned WiMAX can
support the broad range from 3 to 10 kilometres using advanced modulation
algorithm that can overcome many interfering objects that Wi-Fi systems cannot
pass through.
Data Rates
The technology used for WiMAX is Orthogonal Frequency Division Multiplexing
(OFDM), it is not appreciably more supernaturally efficient then the technology Page 15

WIMAX


commonly used for 3G that is Wideband Code Division Multiple Access
(WCDMA). However OFDM is coupled with a high channel bandwidth, that allows
greater data rates. So, on average, for an equivalent spectrum allocation, users will
see similar data rates. In specific simulations, where there are few users, it is
possible that WiMAX will provide a higher data rate than 3G. However, in
commercial systems, such simulations are likely rare.
3.1 DATA RATES
Timing
It is normally believed that WiMAX will enter into the market some five years after
3G is well established. This drawback in time is likely to be important since without
a convincing advantage only a few service providers will choose to move from 3G to
WiMAX. However, those yet to deploy a system may find the choice balanced
between the two technologies.
Cost
The network costs of WiMAX will be likely to be higher than for 3G because of the
reduced range and hence the necessity to build more cells. The subscriber subsidy

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costs may be lower if WiMAX is built into processor chips, although this may not
apply if users wish to have WiMAX handsets.
Quality of Service (QoS)
Excellent Quality Of service management donates from variety of WiMAX features.
Just as on a Wi-Fi network, WiMAX users share a data pipe and QoS can degrade as
more users are added to the network. Using the QoS features of WiMAX service
providers can guarantee certain users specific bandwidth amounts by limiting the
bandwidth consumption of other users.
Grant request mechanism for accessing to network is the first aspect of Quality of
Service. The WiMAX functioning of disagreement allocates only a fixed amount of
time to be given to these grant requests. Disagreement refers to the act of competing
for access to the network. Because of the limited amount of time available,
bandwidth cannot be consumed by contention requests. When a disagreement
request comes into the network, the system compares the request with a service
level agreement for the user making the request, and they are granted, or denied,
access accordingly.
Link by link modulation schemes is another benefit of WiMAX Quality of
Service. In other words, the base station can use different modulation schemes for
different links. The modulation scheme used is related directly to the distance of the
link. Rather than all users' links being downgraded by the user farthest away, link by
link modulation enables closer users to use higher data-rate modulation schemes Page 17

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CHAPTER 4
WiMAX technology
4.1 Technological features
Various advanced technologies will be developed to meet services above and
consequently WiMAX will support seamless mobility and technologies such as the
technique for minimized power consumption of the terminal, fast link adaptation,
and efficient MAC for broadband services will be developed for high data rate
transmission in mobile environments.
4.1 RADIO ACCESS REQUIREMENS
For the phase I standardization, PG302 decided several system parameters and
Radio access requirements. Major system parameters include duplex scheme (TDD)
and multiple access (OFDMA) and Channel bandwidth (10MHz) as well. Any

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detailed contents could be shown in Table 2. For the radio access requirements,
some parameters have been determined as follows:
¢
Frequency reuse factor is set as 1.
¢
Maximum guaranteed speed of user is 60 Km/h.
¢
Radius of service coverage can be a few Km.
¢
Maximum of spectral efficiency should be 6 bits/Hz/cell for downlink and 2
bits/Hz/cell for uplink, but the averages are 2 bits/Hz/cell for downlink and 1
bits/Hz/cell for uplink.
¢
Handoff latency should be less than 150 ms.
¢
Throughout per user should be 0.512 to 3 Mbps for downlink and 0.128 to 1
Mbps for uplink.
Table 4.1 shows the development contents in association with system requirement.
Requirements could be induced by consideration on radio access requirements
Table 4.1
Deployment contents corresponding with system requirements
System Requirements
Deployment contents
High spectrum efficiency
TDD to minimize required guard band
10 MHz broadband/OFDMA Page 19

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Division of Computer Engineering 12
To use AMC(Adaptive Modulation and Coding) supporting 64
QAM modulation with turbo code
Supporting wide coverage
Supporting frequency reuse factor ˜1™
Using Reed Solomon sequence based subchannel to minimize
other RASs interference
In the cell edge with band SINR area, the operation guaranteed
with low rate FEC
Supporting safety channel in order to reduce interference of the
cell edge area
Supporting mobility
Employing H-ARQ to enhanced link performance
Guaranteeing mobility up to 60 km/h speed
Short OFDM symbol length can minimize the degradation due to
the mobility.
The pilot structure supporting channel estimation under mobility.
Flexible resource allocation
for multiple subscriber
Employing variable duty rates of TDD DL/UL
1:1, 2:1, 5:1 DL/UL ratios are available
To support multiple subscriber scheduling algorithm,
management of the status of individual terminals and packet
scheduling algorithm are considered Page 20

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Supporting various QoS
Best effort/Real-time polling/Non-real-time polling
Handheld support
Supporting sleep mode to reduce terminal power consumption
TDD
Smart
Antenna
(optional feature)
To apply the Smart Antenna for low mobility user
4.2 Technology: WiMAX Design
The design of the WiMAX is ideal for challenges related with earlier versions of
wired and wireless access networks. At the same time the backhaul connects the
WiMAX system to the network, it is not an integrated part of WiMAX system.
Normally a WiMAX network consists of two parts, a WiMAX Base Station (BS)
and a WiMAX receiver also referred as Customer Premise Equipment (CPE).
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 Page 21

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Receiver
A WiMAX receiver, which is also referred as Customer Premise Equipment (CPE),
may have a separate antenna or could be a stand-alone box or a PCMCIA card that
inserted in a laptop or a desktop computer. Access to a WiMAX base station is
similar to accessing a wireless access point (AP) in a Wi-Fi network, but the
coverage is more.
So far one of the biggest restrictions to the widespread acceptance of WiMAX has
been the cost of CPE. This is not only the cost of CPE itself, but also that of
installation. In the past, Broadband Wireless Access (BWA) have been
predominantly Line Of Sight (LOS), requiring highly skilled labour and a truck role
to install and provide a service to customer. The concept of a self-installed CPE has
been difficult for BWA from the beginning, but with the advent of WiMAX, this
issue seems to be getting resolvedBase Station (BS)
A WiMAX base station comprises of internal devices and a WiMAX tower. A base
station can normally covers the area of about 50 kilometres or 30 miles radius, but
some other and environmental issues bound the limits of WiMAX range to 10 km or
6 miles. Any wireless user within the coverage area would be able to access the
WiMAX services (Fig: 2). The WiMAX base stations would use the media access
control layer defines in the standard and would allocate uplink and downlink
bandwidth to subscribers according to their requirements on real time basis. Page 22

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4.2 WIMAX TOWER
4.3 Types of WiMAX
The WiMAX family of standards concentrate on two types of usage models a fixed
usage model and a mobile usage model. The basic element that differentiates these
systems is the ground speed at which the systems are designed to manage. Based on
mobility, wireless access systems are designed to operate on the move without any
disruption of service; wireless access can be divided into three classes; stationary,
pedestrian and vehicular.
A mobile wireless access system is one that can address the vehicular class, whereas
the fixed serves the stationary and pedestrian classes. This raises a question about
the nomadic wireless access system, which is referred to as a system that works as a
fixed wireless access system but can change its location

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Fixed WiMAX
Service and consumer usage of WiMAX for fixed access is expected to reflect that
of fixed wire-line service, with many of the standards-based requirements being
confined to the air interface. Because communications takes place via wireless links
from Customer Premise Equipment (CPE) to a remote Non Line-of-sight (NLOS)
base station, requirements for link security are greater than those needed for a
wireless service. The security mechanisms within the IEEE 802.16 standards are
sufficient for fixed access service.
Another challenge for the fixed access air interface is the need to set up high
performance radio links capable of data rates comparable to wired broadband
service, using equipment that can be self installed indoors by users, as is the case for
Digital Subscriber Line (DSL) and cable modems. IEEE 802.16 standards provide
advanced physical (PHY) layer techniques to achieve link margins capable of
supporting high throughput in NLOS environments.
Mobile WiMAX
The 802.16a extension, refined in January 2003, uses a lower frequency of 2 to 11
GHz, enabling NLOS connections. The latest 802.16e task group is capitalizing on
the new capabilities this provides by working on developing a specification to
enable mobile WiMAX clients. These clients will be able to hand off between
WiMAX base stations, enabling users to roam between service areas. Page 24

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CHAPTER 5
WIMAX TECHNOLOGIES CHALLENGE
WiMAX, more flexibility and security
Unlike WLAN, WiMAX provides a media access control (MAC) layer that uses a
grant-request mechanism to authorize the exchange of data. This feature allows
better exploitation of the radio resources, in particular with smart antennas, and
independent management of the traffic of every user. This simplifies the support of
real-time and voice applications. One of the inhibitors to widespread deployment of
WLAN was the poor security feature of the first releases. WiMAX proposes the full
range of security features to ensure secured data exchange:
¢ terminal authentication by exchanging certificates to prevent rogue devices,
¢ user authentication using the Extensible Authentication Protocol (EAP),
¢ data encryption using the Data Encryption Standard (DES) or Advanced
Encryption Standard (AES), both much more robust than the Wireless Equivalent
Privacy (WEP) initially used by WLAN. Furthermore, each service is encrypted
with its own security association and private keys.
WiMAX, a very efficient radio solution
WiMAX must be able to provide a reliable service over long distances to customers
using indoor terminals or PC cards (like today's WLAN cards). These requirements,
with limited transmit power to comply with health requirements, will limit the link
budget. Subchannelling in uplink and smart antennas at the base station has to
overcome these constraints. The WiMAX system relies on a new radio physical Page 25

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(PHY) layer and appropriate MAC layer to support all demands driven by the target
applications. The PHY layer modulation is based on OFDMA, in combination with a
centralized MAC layer for optimized resource allocation and support of QoS for
different types of services (VoIP, real-time and non real-time services, best effort).
The OFDMA PHY layer is well adapted to the NLOS propagation environment in
the 2 - 11 GHz frequency range. It isinherently robust when it comes to handling the
significant delay spread caused by the typical NLOS reflections. Together with
adaptive modulation, which is applied to each subscriber individually according to
the radio channel capability, OFDMA can provide a high spectral efficiency of about
3 - 4 bit/s/Hz. However, in contrast to single carrier modulation, the OFDMA signal
has an increased peak: average ratio and increased frequency accuracy requirements.
Therefore, selection of appropriate power amplifiers and frequency recovery
concepts are crucial. WiMAX provides flexibility in terms of channelization, carrier
frequency, and duplex mode (TDD and FDD) to meet a variety of requirements for
available spectrum resources and targeted services. An important and very
challenging function of the WiMAX system is the support of various
advancedantenna techniques, which are essential to provide high spectral efficiency,
capacity, system performance, and reliability:
¢ beam forming using smart antennas provides additional gain to bridge long
distances or to increase indoor coverage; it reduces inter-cell interference and
improves frequency reuse,
¢ transmit diversity and MIMO techniques using multiple antennas take advantage
of multipath reflections to improve reliability and capacity.
WiMAX technology can provide coverage in both LOS and NLOS conditions.
NLOS has many implementation advantages that enable operators to deliver
broadband data to a wide range of customers. WiMAX technology has many
advantages that allow it to provide NLOS solutions, with essential features such as
OFDM technology, adaptive modulation and error correction. Furthermore,
WiMAX has many optional features, such as ARQ, sub-channeling, diversity, and Page 26

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space-time coding that will prove invaluable to operators wishing to provide quality
and performance that rivals wireline technology. For the first time, broadband
wireless operators will be able to deploy standardized equipment with the right
balance of cost and performance; choosing the appropriate set of features for their
particular business model.
System performance
Table 5.1 gives typical cell size and throughput at 3.5 GHz in various configuration
and environments.
Environment
Typical cell size
Sector throughput
Urban indoor (NLOS) 1 km (5/8 miles) 21 Mbit/s w.10MHz
channel
Suburban indoor (NLOS) 2.5 km (1.5 miles) 22 Mbit/s w.10 MHz
channel
Suburban outdoor (LOS) 7 km (4 miles) 22 Mbit/s w. 10 MHz
channel
Rural indoor (NLOS) 5 km (3 miles) 4.5Mbit/s w.3.5 MHz
channel
Rural outdoor (LOS) 15 km (9 miles) 4.5Mbit/s w.3.5MHz
channel
5.1
Typical Cell Size and Throughput Page 27

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6 ENHANCEMENTS IN WIMAX
OFDM
OFDM stands for Orthogonal Frequency Division Multiplexing; itâ„¢s a technology
that provides the operator to beat the challenges of Non-Line-of-Sight (NLOS)
transmission in the more efficient manner. OFDM waveform put forward the
advantage of functioning with the larger delay spread of the NLOS background.
With the excellent quality of OFDM functionality, time and use of a cyclic prefix
and its also removes the Inter Symbol Interference (ISI) complications of adaptive
equalization. Multiple narrowband orthogonal carriers composed because of OFDM
waveform, localizing selective fading to a subset of carriers that are comparatively
simple to equalize. A comparison between an OFDM signal and a single carrier
signal, with the information being sent in parallel for OFDM and in series for single
carrier are shown in Fig: 6.1 (WiMAX Forum)
6.1 OFDM

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The facility to remove delay spread, Inter Symbol Interference (ISI) and multi-path
in a proficient manner allows for higher data rate throughput. It is simpler to
equalize the individual OFDM carriers than it is to equalize the broader single
carrier signal. For these entire reasons modern international standard such as those
set by IEEE 802.16, have created OFDM as the ideal technology.
Antennas For Fixed WiMAX Applications
Directional antennas enhance the fade margin by adding together extra gain. This
increases the link accessibility comparisons between directional and Omni-
directional antennas. Delay spread is further reduced by directional antennas at both
the Base Station and Customer Premise Equipment (CPE). The antenna pattern
restrains any multi-path signals that appear in the side lobes and back lobes. The
efficiency of these methods has been verified and demonstrated in booming
deployments, in which the service operates under considerable NLOS fading.
Adaptive Modulation
WiMAX system supports adaptive modulation to regulate the Signal Modulation
Scheme (SMC) depending on the Signal to Noise Ratio (SNR) state of the radio
link. When the radio link is soaring in quality, the peak modulation scheme is used,
offering the system additional capacity. During a signal fade, the WiMAX system
can move to a lower modulation scheme to keep the connection quality and link
permanence. This element allows the system to overcome time-selective fading. The
key element of adaptive modulation is that it enhances the range that a higher
modulation scheme can be used over, because the system can bend to the actual
fading circumstances, as opposed to having a fixed scheme that is planned for the
worst case situations.Page 29

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WiMAX & IMT-Advanced
IMT-Advanced, also known as systems beyond IMT-2000 is expected to offer
constant higher data rates with high mobility to assure likely growing need for
mobile WiMAX services that goes beyond what IMT-2000 can afford to provide.
IMT- Advanced is awaiting technology that will require 3 to 5 years in the future
with target maximum data rates, for research and examination, of up to 100
Mbits/sec in high mobility applications and up to 1 Gbit/sec in low mobility or
nomadic applications. The capacity expected by IMT-Advanced is often referred to
as 4G. It is commonly acknowledged that Orthogonal Frequency Division Multiple
Access (OFDMA) technology will be integrated in IMT-Advanced in near future to
get more the maximum benefits from the WiMAX.
IMT-Advanced is a continuing effort. The full criteria, being extended within ITU-
R Working Party 8F, are not expected until 2008. The specification of IMT-
Advanced technologies will probably not be completed until at least 2010. In
preparation for IMT-Advanced, the IEEE 802.16 Working Group has moved to
initiate a new project and implimentation designated as 802.16m with the intent of developing
enhancements to IEEE STD 802.16 to ensure suitability as an IMT-Advanced
proposal.
Power Control
Algorithms of power control are applied to enhance the general performance of the
system, it is deployed by the base station sending power control information to
every Customer Premise Equipments (CPEs) to control the transmit power level so
that the level inward bound at the base station is at a fixed level. In a dynamical
changing fading environment this pre-determined performance level indicates that
the CPE only broadcasts sufficient power to meet this constraint. The
communication would be that the CPE broadcast level is supported on worst case
circumstances. The power control decreases the general power consumption of the
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the transmission power of the CPE is approximately comparative to its distance
from the base station, for Non-Line-Of-Sight (NLOS) it is also closely dependant on
the clearance and barriers.
Error Detection Techniques
WiMAX have built-in error detection techniques to reduce the system Signal to
Noise Ratio (SNR) obligations. Convolutional Encoding, Strong Reed Solomon
FEC, and interleaving algorithms are used to identify and correct errors to enhance
throughput. These strong error correction techniques assist to recover corrupted
frames that may have been missing due to frequency selective fading or burst errors.
To remove the errors, Automatic Repeat Request (ARQ) is used that cannot be
corrected by the FEC by resending the error-ed information again. This notably
improves the Bit Error Rate (BER) performance for a similar maximum level.Page 31

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CHAPTER 7
WIMAX A COMPLEMENT TO A FIXED & MOBILE ACCESS
WiMAX integrates perfectly into existing fixed and mobile networks,
complementing them when needed. This section gives a more detailed analysis of
WiMAX integration into fixed and the mobile markets.
WiMAX for fixed wireless access
Nationwide broadband access has become a priority in many countries. In most
developed countries, the average broadband coverage will reach 90% in the coming
years. Still, in some rural areas of such countries, broadband coverage will not
exceed 50%.The service gap can be categorized by two characteristics: the type of
area (rural or urban) and the level of national development (see Table 1). In
developed countries, DSL service deployment has been massive in urban and sub-
urban deployments, whereas coverage of remote areas - smaller towns and rural
areas - is lagging behind.
Hurdles to overcome are the poor line quality of the installed copper base, the large
distances to the central offices or cabinets, or the low population density. In this
context, WiMAX, with its QoS support, longer reach, and data rates similar to DSL,
is naturally positioned as a viable first mile option to offer broadband access to
residential users.
In emerging countries, the main focus of broadband deployment is on urban and
suburbanareas, and will remain so in the near future. The low POTS penetration and
the low quality of the copper pair prevent mass scale DSL deployment and foster the
need for alternate broadband technologies. In this context, WiMAX is positioned as
an excellent option. Moreover, the possibility of offering broadband services in
combination with voice services will gradually lead to narrowband WLL Page 32

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substitution. Parameters such as availability of the copper, distance to the remote
unit/central office, backhauling costs, and teledensity will drive the choice for one
or other of these solutions. For further details, refer to the article "Providing
Always-on
Broadband Access to Under-served Areas" in the Alcatel Telecommunication
Review(Q4 2003).
WiMax is of interest for large enterprises with several locations in the same
metropolitan area. WiMax will permit Operator's bypass under license conditions:
building a metropolitan private network of IP lines at a very low cost (no civil
works). The comparison to leased lines rental fee is in favor of Wimax even for two
sites only.
Deployment topologies
Several topology and backhauling options are to be supported on the WiMAX base
stations: wireline backhauling (typically over Ethernet), microwave Point-to-Point
connection, as well as WiMAX backhaul. See Figure 3. With the latter option,
thebase station has the capability to backhaul itself. This can be achieved by
reserving part of the bandwidth normally used for the end-user traffic and using it
for backhauling purposes.
WiMAX for Portable Internet
WiMAX, the natural complement to mobile and Wi-Fi networks
Mobile networks offer full mobility, nation-wide coverage voice support and
moderate data rates. WiMAX can then be positioned as a complementary solution
by offering higher bandwidth when required, in particular in dense urban areas.
Public WLAN, while offering clear benefits, is limited in coverage and mobility Page 33

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capabilities. WiMAX by-passes these limitations and offers broadband connectivity
in larger areas (hotzones). Wi-Fi and WiMAX solutions are also complementary,
with Wi-Fi being more adapted for short-range, indoor connections (in particular in
the enterprise and at home) and WiMAX for long- range outdoor connections.
From nomadicity to Portable Internet
While nomadicity offers connectivity within the coverage area of a single base
station, Portable Internet implies session continuity throughout the network. In
addition a new generation of networks with multi-access (3G, Wi-Fi, WiMAX,
DSL, FTTU, etc.) enable end-users to enjoy an "Always Best Connected"
experience when accessing their applications via the best available network at home,
on the pause, or on the move. See Figure 4. WiMAX becomes an additional radio
access solution in the global network architecture.
The WiMAX CPE
In most case, a simple plug and play terminal, similar to a DSL modem, provides
connectivity. For customers located several kilometers from the WiMAX base
station, a self-install outdoor antenna may be required to improve transmission
quality. To serve isolated customers, a directive antenna pointing to the WiMAX
base station may be required. For customers requesting voice in addition to
broadband services, specific CPE will allow the connection of standard or VoIP
phones. Ultimately, WiMAX chipset will be embedded in data-centric devices.
Operator's business case
WiMAX is of interest for incumbent, alternate, and mobile operators. Some
business cases are possible. Page 34

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¢ The incumbent operators can use the wireless technology as a complement to DSL,
allowing them to offer DSL-like services in remote, lowdensity areas that cannot be
served with DSL.
¢ For alternate operators, the wireless technology is the solution for a competitive
high-speed Internet with applicability in urban or sub-urban areas.
¢ The larger opportunity will come with the Portable Internet usage, complementing
fixed and mobile solution in urban and suburban areas. Therefore it will enhance the
business case by giving access to a large potential of end users.
WiMAX, the obvious choice for operators
By integrating WiMAX into their networks, mobile operators can boost their service
with high bandwidth, when necessary, the same applications (messaging, agenda,
location-based services, ¦) being offered on both networks with a single billing and
subscriber profile. Mobile operators can also reuse existing radio sites and
backhauling equipment to facilitate the deployment of WiMAX. Fixed operators,
incumbent or alternate, will offer nomadic and Portable Internet usage as an addition
to their fixed access offering to complement their DSL and Wi-Fi bundle. For those
having deployed WiMAX for fixed access, this is also a natural evolution of their
offering.Page 35

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CHAPTER 8
WIMAX SPECTRUM AND REGULATION ISSUES
WiMAX-compliant equipment will be allowed to operate in both licensed and
unlicensed bands. The minimum channel bandwidth for WiMAX usage is 1.75 MHz
per channel, while 10 MHz is considered as an optimum. Although 2.4 GHz and 5
GHz non-licensed bands are largely available, their usage could be limited to trials
because of the risks of interference preventing QoS commitments. The 2.5 and 3.5
GHz licensed bands will be the most common bands for WiMAX applications. It
should be noted that the 5 GHz band is also partially licensed in some countries.
Most countries have already allocated licensed spectrum, generally to alternate
operators. Nevertheless large quantities of spectrum are still in process of allocation,
and some countries have not even defined any WiMAX licensed bands yet. WiMAX
is designed to accommodate either Frequency Division Duplexing (FDD), which is
more suited to enterprise traffic, or Time Division
Duplexing (TDD), which is more adapted to asymmetrical traffic. Cohabitation of
FDD and TDD techniques is possible within the same bands, provided guard bands
are implemented.
Throughput, Scalability, QoS, and Security
Throughput
By using a robust modulation scheme, IEEE 802.16 delivers high throughput at long
ranges with a highlevel of spectral efficiency that is also tolerant of signal
reflections. Dynamic adaptive modulation allows the base station to tradeoff
throughput for range. For example, if the base station cannot establish a robust link
to a distant subscriber using the highest order modulation scheme, 64 QAM
(Quadrature Amplitude Modulation), the modulation order is reduced to 16 QAM or Page 36

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QPSK (Quadrature Phase Shift Keying), which reduces throughput and increases
effective range.
Scalability
To accommodate easy cell planning in both licensed and license-exempt spectrum
worldwide, 802.16 supports flexible channel bandwidths. For example, if an
operator is assigned 20 MHz of spectrum, that operator could divide it into two
sectors of 10 MHz each, or 4 sectors of 5 MHz each. By focusing power on
increasingly narrow sectors, the operator can increase the number of users while
maintaining good range and throughput. To scale coverage even further, the
operator can re-use the same spectrum in two or more sectors by creating proper
isolation between base station antennas.
Coverage
In addition to supporting a robust and dynamic modulation scheme, the IEEE
802.16 standard also supports technologies that increase coverage, including mesh
topology and smart antenna techniques. As radio technology improves and costs
drop, the ability to increase coverage and throughput by using multiple antennas to
create transmit and/or receive diversity will greatly enhance coverage in
extreme environments.
Quality of Service
Voice capability is extremely important, especially in underserved international
markets. For this reason the IEEE 802.16a standard includes Quality of Service
features that enable services including voice and video that require a low-latency
network. The grant/request characteristics of the 802.16 Media Access Controller
(MAC) enables an operator to simultaneously provide premium guaranteed levels of
service to businesses, such as T1-level service, and high-volume best-effort Page 37

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service to homes, similar to cable-level service, all within the same base station
service area cell.
Security
Privacy and encryption features are included in the 802.16 standard to support
secure transmissions and provide authentication and data encryption.
Benefits of Standards
Standards are important for the wireless industry because they enable economies of
scale that can bring down the cost of equipment, ensure interoperability, and reduce
investment risk for operators. Without industry-wide standards, equipment
manufacturers must provide all the hardware and software building blocks and
platforms for themselves, including the fundamental silicon, the sub- scriber station,
the base station, and the network management software that is used to provision
services and remotely manage the subscriber station. With the 802.16 standard in
place, suppliers can amortize their research and development costs over much higher
product volume. For example, a volume silicon supplier can supply the same
standard component to many equipment makers at a far lower cost than would be
possible if the device manufacturers were required to develop proprietary silicon for
use only by their equipment. Standards also specify minimum performance criteria
for equipment, enabling a common broadband wireless access baseline platform that
equipment manufacturers can use as the foundation for ongoing innovations and
faster time to market. With its broad industry support, the 802.16 standard lets device
manufacturers and solutions vendors do what they do best, achieving overall
price/performance improvements and opening mass-market opportunities that cannot
be equaled by proprietary approaches.Page 38

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WiMAX Focuses on Interoperability
WiMAX (the Worldwide Interoperability for Microwave Access Forum) is a non-
profit corporation formed by equipment and component suppliers, including Intel
Corporation, to promote the adoption of IEEE 802.16 compliant equipment by
operators of broadband wireless access systems. The organization is working to
facilitate the deployment of broadband wireless networks based on the IEEE 802.16
standard by helping to ensure the compatibility and interoperability of broadband
wireless access equipment. In this regard, the philosophy of WiMAX for the
wireless MAN is comparable to that of the Wi-Fi* Alliance in promoting the IEEE
802.11 standard for wireless LANs. In an effort to bring interoperability to
Broadband Wireless Access, WiMAX is focusing its efforts on establishing a unique
subset of baseline features grouped in what is referred to as System Profiles that
all compliant equipment must satisfy. These profiles will establish a baseline
protocol that allows equipment from multiple vendors to interoperate, and that also
provides system integrators and service providers with the ability to purchase
equipment from more than one supplier. System Profiles can address the regulatory
spectrum constraints faced by operators in different geographies. For example, a
service provider in Europe1 operating in the 3.5 GHz band who has been allocated
14 MHz of spectrum is likely to want equipment that supports 3.5 and/or 7 MHz
channel bandwidths and TDD (time-division duplex) or FDD (frequency-division
duplex) operation. Similarly, a WISP in the U.S. using licenseexempt spectrum in
the 5.8 GHz UNII band may desire equipment that supports TDD and a 10 MHz
bandwidth. WiMAX will establish a structured compliance procedure based upon
the proven test methodology specified by ISO/IEC 96462. The process starts with
standardized Test Purposes written in English, which are then translated into
Standardized Abstract Test Suites in a language called TTCN3. In parallel, the Test
Purposes are also used as input to generate test tables referred to as the PICS
(Protocol Implementation Conformance Statement) pro forma. The end result is a
complete set of test tools that WiMAX will make available to equipment developersPage 39

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so they can design in conformance and interoperability during the earliest possible
phase of product development. Typically, this activity will begin when the first
integrated prototype becomes available. Ultimately, the WiMAX suite of
conformance tests, in conjunction with interoperability events, will enable service
providers to choose from multiple vendors of broadband wireless access equipment
that conforms to the IEEE 802.16a standard and that is optimized for their unique
operating environment. Internationally, WiMAX will work with ETSI, the European
Telecommunications Standards Institute, to develop similar test suites for the ETSI
HIPERMAN standard for European broadband wireless metropolitan area access.
WiMAX has key benefits for operators. By choosing interoperable, standards-based
equipment, the operator reduces the risk of deploying broadband wireless access
systems.
¢
Economies of scale enabled by the standard help reduce monetary risk.
¢
Operators are not locked in to a single vendor because base stations will
interoperate with subscriber stations from different manufacturers
¢
.Ultimately, operators will benefit from lower-cost and higher-performance
equipment, as equipment manufacturers rapidly create product innovations based on
a common, standards-based platform. Page 40

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CHAPTER 9
WIMAX SERVICES
Potential services
WiMAX services can have potential applications in various fields. Different
applications can demand different QoS, which can be classified as follows
1. INTERACTIVE SERVICES : Web Browsing, Game interface,etc
2. STREAMING SERVICES : VoD ,MPEG ,etc.
3. BACK GROUND SERVICES: FTP,E-Mail, SMS, Multicast/Broadcast
,MMS, PUSH TO TALK
9.1 SERVICES 1

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Possible services provided by WiMAX are widespread over various data
communication services including entertainment, information and commerce
services. The first round of WiMAX technology is expected to be nomadic, meaning
that CPEs will be portable, but not truly mobile. But with Samsungâ„¢s new
developments on hand-over, the technology may become truly mobile, offering the
20 Mb/s to 30 Mb/s at speeds up to 120 km/h WiMAX enthusiasts are touting. For
entertainment services, WiMAX will provide high quality VoD/MoD/AoD, real-
time streaming broadcasting, 3G network games and MMS. Web Browsing, file
downloading and interactive information services will be provided as information
services by WiMAX. Commerce services such as m-commerce, mobile banking,
trading will be also provided by WiMAX as well. Table 1 summarizes possible
services to be provided by WiMAX. Example of WiMAX Services
Application
Service type
QoS class
VoD/MoD/AoD
Streaming
Realtime-Broadcasting
Real Time
Network Game
Interactive
MMS
Entertainment service
Background
Web Browsing
Interactive
FTP
Background
Interactive information
Information service
Interactive
m-Commerce
Interactive
Mobile banking
Interactive
Stock trading
Commerce service
Interactive

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Current Service
KT offers 18.4Mbit/s/4Mbit/s for $22 a month with unlimited data usage. WiMAX
seems faster than HSDPA. There are similar service in U.S. operated by wireless
company but much more expensive and slower. Hanaro Telecom have announced a
partnership to roll out WiMAX nationwide in Korea, excluding Seoul and six
provincial cities, where independent networks will be rolled out.In November 2004,
Intel and LG Electronics executives agreed to ensure compatibility between
WiMAX and WiMAX technology In September 2005, Samsung Electronics signed
a deal with Sprint Nextel Corporation to provide equipment for a WiMAX trial. In
November 2005, KT Corporation(aka Korea Telecom) showed off WiMAX trial
services during the Asia-Pacific Economic Cooperation (APEC) summit in Busan.
9.2 SERVICES2
February 10th 2006: Telecom Italia, the dominant telephony and internet service
provider in Italy, together with Korean Samsung Electronics, has demonstrated to
the public a WiMAX network service on the occasion of the 2006 Winter Olympics,
held in Turin, with downspeed of 10 Mbit/s and upspeed of some hundreds of kbit/s
even in movement up to 120 km/h.

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In the same event Samsung tlc div. president Kitae Lee assured a future of 20-30
Mbit/s by the end of this year (2006) and 100+ Mbit/s down / 1+ Mbit/s up in 2008
KT Corporation launched commercial WiMAX service in mid-2006 as reported
Sprint (US), BT (UK), KDDI (JP), and TVA (BR) have or are trialing WiMAX. KT
Corporation and SK Telecom launched WiMAX around Seoul on June 30, 2006.
More about the KT launch.On April 3, 2007, KT launched WiMAX coverage for all
areas of Seoul including all subway lines.
Broadband access - In your home, you have either a DSL or Cable Modem. At the office, your company may be using a T1 or a T3 line.

WiFi access - In your home, you may have set up a WiFi router that lets you surf the Web while you lounge on the deck with your laptop. On the road, you can find WiFi hot spots in restaurants, hotels, coffee shops and libraries.

[img]static.howstuffworksgif/wimax-2.jpg[/img]

Dial-up access - If you are still using dial-up, chances are that either:
Broadband access is not available.
You think that broadband access is too expensive.

The main problems with broadband access are that it is pretty expensive and it doesn't reach all areas. The main problem with WiFi access is that hot spots are very small, so coverage is sparse.

What if there were a new technology that solved all of these problems? This new technology would provide:
The high speed of broadband service
Wireless rather than wired access, so it would be a lot less expensive than cable or DSL and much easier to extend to suburban and rural areas
Broad coverage like the cell phone network instead of the tiny little hotspots of WiFi
This system is actually coming into being right now, and it is called WiMAX. WiMAX is short for Worldwide Interoperability for Microwave Access, and it also goes by the IEEE name 802.16.
[img]static.howstuffworksgif/wimax-diagram.gif[/img]
WiMAX has the potential to do to broadband Internet access what cell phones have done to phone access. In the same way that many people have given up their "land lines" in favor of cell phones, WiMAX could replace cable and DSL services, providing universal Internet access just about anywhere you go. WiMAX will also be as painless as WiFi -- turning your computer on will automatically connect you to the closest available WiMAX antenna.

In this article, we'll find out how WiMAX works, what engineers are doing to make it better and what it could mean for the future of wireless Internet.



How WiMAX Works
In practical terms, WiMAX would operate similar to WiFi but at higher speeds, over greater distances and for a greater number of users. WiMAX could potentially erase the suburban and rural blackout areas that currently have no broadband Internet access because phone and cable companies have not yet run the necessary wires to those remote locations.

A WiMAX system consists of two parts:
A WiMAX tower, similar in concept to a cell-phone tower - A single WiMAX tower can provide coverage to a very large area -- as big as 3,000 square miles (~8,000 square km).

A WiMAX receiver - The receiver and antenna could be a small box or PCMCIA card, or they could be built into a laptop the way WiFi access is today.
A WiMAX tower station can connect directly to the Internet using a high-bandwidth, wired connection (for example, a T3 line). It can also connect to another WiMAX tower using a line-of-sight, microwave link. This connection to a second tower (often referred to as a backhaul), along with the ability of a single tower to cover up to 3,000 square miles, is what allows WiMAX to provide coverage to remote rural areas.



What this points out is that WiMAX actually can provide two forms of wireless service:
There is the non-line-of-sight, WiFi sort of service, where a small antenna on your computer connects to the tower. In this mode, WiMAX uses a lower frequency range -- 2 GHz to 11 GHz (similar to WiFi). Lower-wavelength transmissions are not as easily disrupted by physical obstructions -- they are better able to diffract, or bend, around obstacles.

There is line-of-sight service, where a fixed dish antenna points straight at the WiMAX tower from a rooftop or pole. The line-of-sight connection is stronger and more stable, so it's able to send a lot of data with fewer errors. Line-of-sight transmissions use higher frequencies, with ranges reaching a possible 66 GHz. At higher frequencies, there is less interference and lots more bandwidth.

WiFi-style access will be limited to a 4-to-6 mile radius (perhaps 25 square miles or 65 square km of coverage, which is similar in range to a cell-phone zone). Through the stronger line-of-sight antennas, the WiMAX transmitting station would send data to WiMAX-enabled computers or routers set up within the transmitter's 30-mile radius (3,600 square miles or 9,300 square km of coverage). This is what allows WiMAX to achieve its maximum range.
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ABSTRACT:-
The surge of internet explosion has lead to devlopment in various fields of science and technology escpecially in the fields of telecommunications.Think about how you access the Internet today. There are basically three different options
¢ Broadband access.
¢ WiFi access
¢ Dial-up access
The main problems with broadband access are that it is pretty expensive and it doesn't reach all areas. The main problem with WiFi access is that hot spots are very small, so coverage is sparse. The new technology should provide high speed of Broad band service, wireless access, less expensive and should provide wider coverage like cell phone network instead of all WiFi hotspots. In this paper weâ„¢ll find out how WiMAX works,how it can improvised over other competing technologies and its practical implementations .
INTRODUCTION
WiMAX is defined as Worldwide Interoperability for Microwave Access by the WiMAX Forum, formed in June 2001 to promote conformance and interoperability of the IEEE 802.16 standard, officially known as WirelessMAN. It is a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL. WiMAX will provide fixed, nomadic, portable and mobile wireless broadband connectivity without the need for direct line-of-sight with a base station. In a typical cell radius deployment of three to 10 kilometers. WiMAX is 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.

Wimax is the real wireless architecture by which wireless range can be extended to 49.6 kms compared with Wi-Fi 91 mts and bluetoothâ„¢s 9 mts.
It also boasts 70 Mbps of the data rates that support thousands of users.

Why is WiMAX needed?

It is important to understand the current state of technical fragmentation of the broadband wireless industry. Early broadband wireless systems began as extensions of indoor local area network (LAN) technology known as Wifi or the 802.11b protocol. This standard has evolved into a ubiquitous and widely available standard used in short range hotspots all over the globe. However, the media access controller (MAC) and physical layer (PHY) specifications for this protocol are sub optimum for outdoor citywide wireless networks or metropolitan area networks (MAN).
Recent updates and new standards such as 802.11g and 802.11a have improved these elements. However, once again these technologies are configured for best performance in small venues and at short range. To compensate vendors developed proprietary MAC and PHY layers based on the root LAN standard of 802.11. Many of these systems are in use today
and possess significant improvements
in modulation scheme, polling technology and data transport that enable effective and modestly affordably citywide or rural wireless networks. However, none of these proprietary iterations of the technology are exactly the same. No two companyâ„¢s products will work with each other. This means that broadband wireless carriers must use base stations and customer premise equipment from the same vendor in any given city---which may not be the best solution in some geographic and radio frequency (RF) environments.
Fundamental technologies in 802.16:
OFDM (OrthogonalFrequency Division Multiplexing):-

It is fundamental technology in digital TV .It transmits multiple signals simultaneously across the wireless transmission with in separate frequency to avoid interference .It is also supported in WLAN standard .OFDM will almost certainly become the dominant technology in all wireless technologies .
ADAPTIVE MODULATION:-

Many systems in the past decade have involved in the fixed modulation offering a trade off between higher order modulations for higher data rates, but requiring more optimal links or more robust lower order that will operate only at lower data rates .But 802.16 supports adaptive delta modulation balancing different data rates and link quality, making most efficient use of band width.
FDD AND TDD:-
The standard also supports both frequency and time division multiplexing to enable interoperability with cellular and other wireless systems .FDD has widely deployed in cellular telephony .It requires two channel pairs. One for transmission and other for reception with some frequency separation between them to migrate self-interference .TDD uses a single channel for both upstreams and downstream transmissions , dynamically allocating bandwidth requirement depending on the traffic requirements
How WiMAX works?
A WiMAX system consists of two parts:
I. A WiMAX tower, similar in concept to a cell-phone tower - A single WiMAX tower can provide coverage to a very large area -- as big as 3,000 square miles (~8,000 square km).
II. A WiMAX receiver - The receiver and antenna could be a small box or PCMCIA card, or they could be built into a laptop the way WiFi access is today.
A WiMAX tower station can connect directly to the Internet using a high-bandwidth, wired connection. It can also connect to another WiMAX tower using a line-of-sight, microwave link. This connection to a second tower (often referred to as a backhaul), along with the ability of a single tower to cover up to 3,000 square miles, is what allows WiMAX to provide coverage to remote rural areas.
What this points out is that WiMAX actually can provide two forms of wireless service:
I. There is the non-line-of-sight, WiFi sort of service, where a small antenna on your computer connects to the tower. In this mode, WiMAX uses a lower frequency range -- 2 GHz to 11 GHz (similar to WiFi). Lower-wavelength transmissions are not as easily disrupted by physical obstructions -- they are better able to diffract, or bend, around obstacles.
II. There is line-of-sight service, where a fixed dish antenna points straight at the WiMAX tower from a rooftop or pole. The line-of-sight connection is stronger and more stable, so it's able to send a lot of data with fewer errors. Line-of-sight transmissions use higher frequencies, with ranges reaching a possible 66 GHz. At higher frequencies, there is less interference and lots more bandwidth.
WiFi-style access will be limited to a 4-to-6 mile radius (perhaps 25 square miles or 65 square km of coverage, which is similar in range to a cell-phone zone). Through the stronger line-of-sight antennas, the WiMAX transmitting station would send data to WiMAX-enabled computers or routers set up within the transmitter's 30-mile radius (2,800 square miles or 9,300 square km of coverage). This is what allows WiMAX to achieve its maximum range.
What WiMAX can do?
WiMAX operates on the same general principles as WiFi -- it sends data from one computer to another via radio signals. A computer equipped with WiMAX would receive data from the WiMAX transmitting station, probably using encrypted data keys to prevent unauthorized users from stealing access.
The fastest WiFi connection can transmit up to 54 megabits per second under optimal conditions. WiMAX should be able to handle up to 70 megabits per second. Even once that 70 megabits is split up between several dozen businesses or a few hundred home users, it will provide at least the equivalent of cable-modem transfer rates to each user.
The biggest difference isn't speed; it's distance. WiMAX outdistances WiFi by miles. WiFi's range is about 100 feet (30 m). WiMAX will blanket a radius of 30 miles (50 km) with wireless access. The increased range is due to the frequencies used and the power of the transmitter. Of course, at that distance, terrain, weather and large buildings will act to reduce the maximum range in some circumstances, but the potential is there to cover huge tracts of land.
IEEE
802.16 Specifications
¢ Range - 30-mile (50-km) radius from base station
¢ Speed - 70 megabits per second
¢ Line-of-sight not needed between user and base station
¢ Frequency bands - 2 to 11 GHz and 10 to 66 GHz (licensed and unlicensed bands)
IEEE Standards:-
The current 802.16 standard is IEEE Std 802.16e-2005 approved in December 2005. It followed on from IEEE Std 802.16-2004, which replaced IEEE Standards 802.16-2001, 802.16c-2002, and 802.16a-2003.
IEEE Std 802.16-2004 (802.16d) addresses only fixed systems. 802.16e adds mobility components to the standard
FEATURES OF 802.16a:-
802.16a is a version of wimax and offers excellent capabilities. The typical cell radius of 802.16a systems is expected to be four to six miles. This new standard will help the industry provide solutions across multiple broadband segments. The features are as follows.
Broadband on-demand “
802.16a wireless technology enables a service provider to provide service with speed comparable to a wired solution in a matter of days, and at significantly reduced cost. It also enables instantly configurable 'on demand' high-speed connectivity for temporary events such as trade shows.
Cellular backhaul:-
The robust bandwidth of 802.16 technologies makes it an excellent choice to carry backhaul traffic for cellular base stations in a point-to-point configuration.
Residential broadband:-
Filling the gaps in cable and DSL coverage - Practical limitations prevent cable and DSL technologies from reaching many potential broadband customers. This will change with the launch of standards-based systems based on 802.16a.
Underserved areas:-
Wireless internet technology based on IEEE 802.16 is also a natural choice for underserved rural and outlying areas with low population density.
Best-connected wireless
Service: - The IEEE 802.16e extension to 802.16a introduces nomadic capabilities which will allow users to connect while roaming outside their home areas.
IEEE 802.16e
IEEE 802.16e formally named, but still best known as, 802.16e or Mobile WiMAX provides an improvement on the modulation schemes stipulated in the original WiMAX standard. It allows for fixed wireless and mobile Non Line of Sight applications primarily by enhancing the OFDMA.
Advantages over Wi-Fi
In practical terms, WiMAX would operate similar to WiFi but at higher speeds, over greater distances and for a greater number of users.
? The WiMAX specification provides symmetrical bandwidth over many kilometers and range with stronger encryption and typically less interference.
? Wi-Fi is short range has WEP or WPA encryption and suffers from interference as in metropolitan areas where there are many users.
? It provides connectivity between network endpoints without the need for direct line of sight in favourable circumstances. The non-line-of-sight propagation (NLOS) performance requires the .16d or .16e revisions, since the lower frequencies are needed. It relies upon multi-path signals, somewhat in the manner of 802.11n.
WiMAX Systems:-
This figure shows that wimax systems may be used to provide point to point and point to multi point communication service can provide different types of communication service from a common digital system this diagram shows that wimax can be used to provide dedicated high speed data links to hundreds of user in relatively large geographical area.
WiMAX Radio:-
At the core of WiMAX is the WiMAX radio. A radio contains both a transmitter (sends) and a receiver (receives). It generates electrical oscillations at a frequency known as the carrier frequency (in WiMAX that is usually between 2 and 11 GHz). A radio might be thought of as a networking device similar to a router or a bridge in that it is managed by software and is composed of circuit boards containing very complex chip sets.
WiMAX architecture, very simply put, is built upon two components: radios and antennas. Most WiMAX products offer a base station radio separate from the antenna. Conversely, many CPE devices are also two piece solutions with an antenna on the outside of the building and subscriber station indoors as illustrated in the figure below.
Figure 9: Most WiMAX solutions use radios separate from antennas
The chief advantage of this is that the radio is protected from extremes of heat cold and humidity all of which detract from the radio's performance and durability. In addition, having the antenna outdoors optimizes the link budget (performance of the wireless connection) between transmitter and receiver especially in line of sight scenarios. The antenna is connected to WiMAX radio via a cable known as a "pigtail". One simple rule for wireless installations: keep the pigtail as short as possible. Why? The longer the pigtail the more signal is lost between the antenna and the radio.
WiMAX ACESS DEVICES:-
For deploying wimax technology there are wide range of devices available which includes terminal units, internal radio modules ,network interface cards ,PMCIA cards ,external boxes that connect to Ethernet of various communication devices .some of those devices are shown in following figures

APPLICATIONS:-

There may be many usage scenarios
That can be addressed by wimax.
Following are some mobility usages of
WiMAX .
Cellular backhaul:-
The market for cellular services
Becoming more and more competitive .To stay in the business, the cellular operators are constantly looking for ways to reduce the operating costs.
Backhaul costs for cellular operators will represent a significant position of their recurring costs .WiMAX can provide point “to “point links up to 30 miles with data rates capable of supporting multiple E1/T1s cellular can therefore use WiMAX equipment to backhaul base station traffic to their Network operations and switching centers as shown below
Banking networks :-
Large banks can connect their branches and ATM sites to their regional offices through a private WiMAX carrying voice ,data and video traffic as shown below . These spread over a wide area and need high security and band width to handle the traffic .
Campus connectivity:- Government agencies, large enterprises industrial campuses, transportation hubs, universityâ„¢s, and colleges can use
WiMAX to connect multiple locations, sites and offices with in their campus as shown below .campus systems require high data capacity low latency, a large coverage foot print and high security
.
CONCLUSION:-
WiMAX could potentially erase the suburban and rural blackout areas that currently have no broadband Internet access because phone and cable companies have not yet run the necessary wires to those remote locations.

WiMAX can also solve the problem of how to keep wireless notebooks and other mobile devices connected between 802.11 hotspots. An 802.16e amendment will add mobility to 802.16. As early as 2008, 802.16 could be
Incorporated into end-user devices the move
hey
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Presented By:
L. SRINIVASA MURTHY.
III / IV B-Tech ECE
K.SASIDHAR.
III / IV B-Tech ECE
QIS COLLEGE OF ENGINEERING & TECHNOLOGY
VENGAMUKKALAPALEM”ONGOLE
PRAKASAM DISTRICT


ABSTRACT:

The Presentation intended to review the advancements in Networking how they
find their application in different areas of communication.
Networking makes communication easy ,
Wireless Networking gives us Mobility.
WiMax has helped push the wireless communication scenario into hyperdrive.For many years
cables ruled the world. Optical fibers played a dominant role for its higher bit rates and faster
transmission. But the installation of cables caused a greater difficulty and thus led to wireless
access. The foremost of this is Bluetooth which can cover 9-10mts. Wi-Fi followed it having
coverage area of 91mts. No doubt, introduction of Wi-Fi wireless networks has proved a
revolutionary solution to last mile problem.
However, the standard's original limitations for data exchange rate and range, number of
channels, high cost of the infrastructure have not yet made it possible for Wi-Fi to become a
total threat to cellular networks on the one hand, and hard-wire networks, on the other. But
the mans continuous quest for even better technology despite the substantial advantages of
present technologies led to the introduction of new, more up-to-date standards for data
exchange rate i.e., WiMAX.
WiMax provides broadband communication in the area of over 49 km in range with the
bandwidth comparable to that for cable bands - up to 10 Mbit/s and higher. The WiMAX
technology allows operating in any conditions, including in the dense urban coverage, and
providing a high quality of communications and data transmission rate. It provided an
alternative solution to last mile problem by implementing broadband "last mile"
connections, deployment of wireless access point, arrangement of high-speed communication
among company branches and solution of other similar tasks. This paper presents WiMax
technology, its features, real time and coming application areas.
We are very happy to place this paper before the academic fraternity. Now it will be our
pleasure to receive the readerâ„¢s feedback. We feel such a feedback is vital to improving the
knowledge of an efficient engineer, thereby achieving its purpose.
Key words: Last mile, Bluetooth, WiMax , Wi-Fi.

INTRODUCTION:

The wireless revolution is underway, and devices based on radio technologies are
expected to become a significant market in the next several years. Mobile phones,
cordless phones, walkie-talkies, car door openers, and garage door openers are just a few
examples of radio devices that have already achieved widespread adoption in the
marketplace. Out of the past several years, innovations in wireless radio technology such as
Bluetooth,Wi-Fi (ieee-802.11b) and WiMax (ieee-802.16e) have captured our attention.
Some pitfalls in has led to the advent of wimax technology. WiMax offers some advantages
over WiFi, a similar wireless technology, in that it offers a greater range and is more
bandwidth-efficient. Ultimately, WiMax may be used to provide connectivity to entire cities,
and may be incorporated into laptops to give users an added measure of mobility.
WiMax requires a tower, similar to a cell phone tower, which is connected to the Internet
using a standard wired high-speed connection, such as a T3 line. But as opposed to a
traditional Internet Service Provider (ISP), which divides that bandwidth among customers
via wire, it uses a microwave link to establish a connection.
Because WiMax does not depend on cables to connect each endpoint, deploying WiMax to
an entire high- rise, community or campus can be done in a matter of a couple days, saving
significant amounts of manpower.
WHY WIMAX?
The reason for pushing into WiMax technology is because of pitfalls of earlier technologies
i.e., Bluetooth and Wi-Fi.Lets see the comparisons and features of those two technologies.
BluetoothversusWiFi:

WHAT IS WIMAX?

WiMax (worldwide Interoperability for Microwave Access) is the recently approved IEEE
802.16 wireless metropolitan area network (MAN) standard for wireless access. WiMax is
the real wireless architecture by which the wireless access range can extended to 49.6Kms
compared with Wi-Fi 91mts and Bluetoothâ„¢s 9mts. WiMax 802.16 has a single carrier
modulation scheme that operates between 10GHz and 66GHz radio frequency and requires
line of sight towers for the connection to work. The new ratified 802.16a extension uses a
lower frequency range of 2GHz to 11GHz, and does not require line of sight towers. It also
boasts 70Mbps data transfer rate that can support thousands of users.

ARCHITECTURE OF WiMax:

The core components of a WiMax system are the subscriber station (SS) and the base station
(BS). A BS and one or more SSâ„¢s can form a cell with point to multipoint (P2MP) structure.
An 802.16 based system often uses fixed antenna at the subscriber station site. The antenna is
mounted on the roof. Provisions such as adaptive antenna systems and sub channel stations
are also supported by this system.
A BS typically uses either directional or omni directional antennas. A fixed SS typically uses
directional antenna while mobile or portable SS uses an omni directional antenna. Multiple
BSâ„¢s can be configured to form a cellular wireless network. The 802.16 standard also can be
used in a point to point topology with pairs of directional antennas. This increases the
effective range of the system compared to what can be achieved in the P2MP mode.

FUNDAMENTAL TECHNOLOGIES IN 802.16:

OFDM (Orthogonal Frequency Division Multiplexing):
It is fundamental technology in digitital TV. It transmits multiple signals simultaneously
across the wireless transmission paths within separate frequencies to avoid interference. It is
also supported in the WLAN standard. OFDM will almost certainly become dominant in all
wireless technologies.
ADAPTIVE MODULATION:
Many systems in the past decade have involved in the fixed modulation, offering a trade off
between higher order modulation for high data rates, but requiring optimal links or more
robust lower order that will only operate at low data rates. But 802.16 supports adaptive
modulation, balancing different data rates and link quality, making most efficient use of
bandwidth.

FDD AND TDD:

The standard also supports both frequency and time division multiplexing to enable
interoperability with cellular and other wireless system. FDD has been widely deployed in
cellular telephony. It requires two channel pairs. One for transmission and other for reception,
with some frequency separation between them to migrate self- interference. TDD uses a single
channel for both upstream and downstream transmissions, dynamically allocating bandwidth
depending on traffic requirements.

FEATURES OF WIMAX:

The WiMAX standard has been developed with many objectives in mind. These are
summarized below:

1. Flexible Architechure:

Wimax supports several system architectures, including Point-to-Point, Point- to-Multipoint,
and ubiquitous coverage. The WiMAX MAC (Media Access Control) supports Point- to-
Multipoint and ubiquitous service by scheduling a time slot for each subscriber
station(SS).If there is only one SS in the network, the WIMAX Base Station (BS) will
communicate with the SS on a Point-to-Point basis. A BS in a Point-to-Point configuration
may
use
narrower
beam
antenna
to
cover
longer
distances.

2. High Security:

WiMAX supports AES (Advanced Encryption Standard) and 3DES (Triple DES, where
DES is the Data Encryption Standard). By encrypting the links between the BS and the SS,
WiMAX provides subscribers with privacy (against eavesdropping) and security across
the broadband wireless interface. Security also provides operators with strong protection
against theft of service. WiMAX also has built- in VLAN support, which provides
protection for data that is being transmitted by different users on the same BS.

3. Quick Deployment:

Compared with the deployment of wired solutions, WiMAX requires little or no external
plant construction. For example, excavation to support the trenching of cables is not
required. Operators that have obtained licenses to use one of the licensed bands, or that plan
to use one of the unlicensed bands, do not need to submit further applications to the
Government. Once the antenna and equipment are installed and powered, WiMAX is ready
for service. In most cases, deployment of WiMAX can be completed in a matter of hours,
compared with months for other solutions.
4. Multi-Level Service:
The manner in which QoS is delivered is generally based on the Service Level Agreement
(SLA) between the service provider and the end-user. Further, one service provider can
offer different SLAs to different subscribers, or even to different users on the same SS.
5. Interoperability:
WiMAX is based on international, vendor- neutral standards which make it easier for end-
users to transport and use their SS at different locations, or providers. Interoperability
protects the early investment of an with different service operator since it can select
equipment from different equipment vendors, and it will continue to drive the costs
of equipment down as a result of mass adoption.
6. Portability:
As with current cellular systems, once the WiMAX SS is powered up, it identifies itself,
determines the characteristics of the link with the BS, as long as the SS is registered in the
system database, and then negotiates its transmission characteristics accordingly.
7. Mobility:

The IEEE 802.16e amendment has added key features in support of mobility.
Improvements have been made to the OFDM and OFDMA physical layers to support
devices and services in a mobile environment. These improvements, which include
Scaleable
OFDMA,
MIMO,
and
support
for
idle/sleep
mode
and
hand-off
will allow full mobility at speeds up to 160 km/hr. The WiMAX Forum-supported
standard has inherited OFDM's superior NLOS (Non-Line of Sight) performance and
multipath-resistant operation, making it highly suitable for the mobile environment.
8. Cost-effective:
WiMAX is based on an open, international standard. Mass adoption of the standard, and
the use of low-cost, mass-produced chipsets, will drive costs down dramatically, and the
resultant competitive pricing will provide considerable cost savings for service providers and
end-users

9. Wider Coverage:

WiMAX dynamically supports multiple modulation levels including BPSK, QPSK, 16-
QAM and 64-QAM. When equipped with a high-power amplifier and operating with a
low- level modulation (BPSK or QPSK, for example), WiMAX systems are able to cover a
large geographic area when the path between the BS and the SS is unobstructed.
10. Non-Line-of-Sight Operation:
NLOS usually refers to a radio path with its first Fresnel zone completely blocked.
WiMAX is based on OFDM technology, which has the inherent capability of
handling NLOS environments. This capability helps WIMAX products deliver broad
bandwidth in a NLOS environment, which other wireless product cannot do.

11. High Capacity:

Using higher modulation (64-QAM) and channel bandwidth (currently 7MHz, with
planned evolution towards the full bandwidth specified in the associated IEEE and ETSI
standards),WiMax
systems
can
provide
significant
bandwidth
to
end- users.

WIMAX ACCESS DEVICES:

This figure shows some of the different types of WiMax access devices. This diagram
shows that access devices include network termination units, internal radio modules,
network interface cards, PCMCIA cards, external boxes that connect to Ethernet or USB
sockets on communication devices.
WIMAX SYSTEMS:
This figure shows that WiMax systems may be use to provide point to point (PMP) or point
to multipoint (PMP) communication services and that WiMax systems can provide different
types of communication services (voice, data and video) from a common digital switching
system. This diagram also shows that WiMax system can be used to provide dedicated high-
speed data communication links or it may be used to provide broadband wireless service to
hundreds of users in relatively large geographic area.

APPLICATIONS:

There are many usage scenarios that can be addressed by WiMAX. The following are
some mobility usage applications of WiMAX.
1.Cellular Backhaul:
The market for cellular services is becoming more and more competitive. To stay in the
business, cellular operators are constantly looking for ways to reduce operating costs.
Backhaul costs for cellular operators represent a significant portion of their recurring
costs
WiMAX can provide Point-to-Point links of up to 30 miles (50 km), with data rates
capable of supporting multiple E1/T1s Cellular operators can therefore use WiMAX
equipment to backhaul Base Station traffic to their Network Operation and Switching
Centers, as shown below:
2. Banking Networks:
Large banks can connect branches and ATM sites to their
shown below. These banks are normally spread over a large area and need high security and
bandwidth to handle the traffic.

3. Offshore communication:

Oil and gas producers can use WiMAX equipment to provide communication links
from land-based facilities to oilrigs and platforms, to support remote operations,
security,
and
basic
communications.
Remote
operations
include
remote
troubleshooting of complex equipment problems, site monitoring, and database
access. WiMAX networks are quickly and easily deployed. The network can be set
up or redeployed in a matter of hours, if not minutes, even when oilrigs and platforms
are moved to other locations. wired solutions are not appropriate for this scenario,
because the facilities are offshore, and since oilrigs are temporarily located and
moved regularly within the oil or gas field.

4.EducationNetworks:

School boards can use WiMAX networks to connect schools and school board
offices within a district, as shown below. Some of the key requirements for a school
system are NLOS, high band- width (>15 Mbps), Point-to-Point and Point- to-
Multipoint capability, and a large coverage footprint

5. Public Safety:

Government public safety agencies, such as police, fire, and search and rescue, can
use WiMAX networks to support response to medical and other emergency situations, as
illustrated below:

6. Campus Connectivity:

Government agencies, large enterprises, industrial campuses, transportation hubs,
universities, and colleges, can use WiMAX networks to connect multiple locations, sites and
offices within their campus, as shown below. Campus systems require high data capacity,
low latency, a large coverage footprint, and high security:
Disadvantages of WiMax:
We have designed WiMax mainly for large distance communication. The main obstacle to
long distance communications are limitations on battery power and poor power efficiency
CHIPADVANCESSadHow can we overcome drawback?)
The main obstacles to long distance wireless communications are limitations on battery
power and poor power efficiency. Regulation keeps the power levels low and the range of
Wi-Fi signals short, to avoid the overcrowding of airwaves. But advances in DSP chips mean
that weak signals can be deciphered, lengthening the distance that is practical for
transmission, as well as improving distance and speed potential. Battery improvement is vital
to make a WiMax cell phone a practicality.Nokia is working on battery and handset chip
designs towards this end. Intel is increasingly involved in next generation battery and
processing power for mobile devices, including digital radios that can intelligently tune in to
the most efficient network like Cellular,Wi-Fi,Bluetooth,WiMax.

AT PRESENT:

At present we are using WiMax in different areas. The following are the real time
applications of WiMax technology.1. Interactive gaming.
2. VoIP, Video conference
3. Streaming media.

IN FUTURE:

In coming years WiMax also plays a vital role in
1.Information Technology
2.Media content download

CONCLUSION:

Within five years, we expect WiMax to be the dominant technology for wireless networking.
By that time it will be fully mobile, as well as providing low-cost, fixed broadband access
that will open up regions where internet access has no far not been practical.WiMax will be
the most significant technology in making wireless access ubiquitous and, as the free
spectrum is opened up, in creating a major shake-up of the traditional shape of the wireless
and mobile communications sector.

REFERENCES:

Information Technology magazine (oct 2006)
2)
IEEE magazines
intelsemiworks.com
houstuffworks.com
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.doc   wimax seminar.doc (Size: 50 KB / Downloads: 63)
Introduction

WiMAX (World Interoperability for Microwave Access), based on IEEE802.16 standard is a broadband wireless technology that enjoys widespread support from both the computer and telecom industries worldwide, making this technology particularly costeffective. It is engineered to deliver significant business benefits to operators and users in diverse environments (enterprise, consumer, emerging, public service), geographies and demographies (urban, suburban, rural), both over the short and long terms. This paper attempts to present the key technical features and applications of WiMAX, and illustrate them by providing examples of usage scenarios in which WiMAX would be the preferred solution.
There are two main applications of WiMAX today: fixed WiMAX applications And mobile applications. Fixed applications are point to multipoint enabling broadband access to homes and businesses. Mobile applications offer full mobility of cellular networks at true broadband speed.There are many usage scenarios that can be addressed , however, the limited length of this paper means that we cannot address all of them. For this reason, the paper is primarily focused on fixed and portable usage; however, some examples of mobility usage have also been included.
WiMAX technology makes the following possible:
• Make portable internet a reality by extending public WLAN hotspots to metropolitan area coverage for mobile data-centric service delivery
• Connect enterprises and residentialv users in urban and suburban environment where access to copper plant/wire network is difficult.
• Bridge the digital divide by delivering broadband in low density areas.




WiMAX Technology


The WiMAX standard has been developed with many objectives in mind. These are summarized below:
High Security
•Flexible Architecture: WiMAX supports several system architectures, including Point-to-Point, Point-to-Multipoint, and ubiquitous coverage. The WiMAX MAC (Media Access Control) supports Point-to-Multipoint and ubiquitous service by scheduling a time slot for each Subscriber Station (SS). If there is only one SS in the network, the WiMAX Base Station (BS) will communicate with the SS on a Point-to-Point basis. A BS in a Point-to-Point configuration may use a narrower beam antenna to cover longer distances.

•High Security: WiMAX supports AES (Advanced Encryption Standard) and 3DES (Triple DES, where DES is the Data Encryption Standard). By encrypting the links between the BS and the SS, WiMAX provides subscribers with privacy (against eavesdropping) and security across the broadband wireless interface. Security also provides operators with strong protection against theft of service. WiMAX also has built-in VLAN support, which provides protection for data that is being transmitted by different users on the same BS.
AX Service Types
•Quick Deployment: Compared with the deployment of wired solutions, WiMAX requires little or no external plant construction. For example, excavation to support the trenching of cables is not required. Operators that have obtained licenses to use one of the licensed bands, or that plan to use one of the unlicensed bands, do not need to submit further applications to the Government. Once the antenna and equipment are installed and powered, WiMAX is ready for service. In most cases, deployment of WiMAX can be completed in a matter of hours, compared with months for other solutions.

•Multi-Level Service: The manner in which QoS is delivered is generally based on the Service Level Agreement (SLA) between the service provider and the end-user. Further, one service provider can offer different SLAs to different subscribers, or even to different users on the same SS.

•Interoperability: WiMAX is based on international, vendor-neutral standards, which make it easier for end-users to transport and use their SS at different locations, or with different service providers. Interoperability protects the early investment of an operator since it can select equipment from different equipment vendors, and it will continue to drive the costs of equipment down as a result of mass adoption.

•Portability: As with current cellular systems, once the WiMAX SS is powered up, it identifies itself, determines the characteristics of the link with the BS, as long as the SS is registered in the system database, and then negotiates its transmission characteristics accordingly.

•Mobility: The IEEE 802.16e amendment has added key features in support of mobility. Improvements have been made to the OFDM and OFDMA physical layers to support devices and services in a mobile environment. These improvements, which include Scaleable OFDMA, MIMO, and support for idle/sleep mode and hand-off, will allow full mobility at speeds up to 160 km/hr. The WiMAX Forum-supported standard has inherited OFDM’s superior NLOS (Non-Line Of Sight) performance and multipath-resistant operation, making it highly suitable for the mobile environment.

•Cost-effective: WiMAX is based on an open, international standard. Mass adoption of the standard, and the use of low-cost, mass-produced chipsets, will drive costs down dramatically, and the resultant competitive pricing will provide considerable cost savings for service providers and end-users.

•Wider Coverage: WiMAX dynamically supports multiple modulation levels, including BPSK, QPSK, 16-QAM, and 64-QAM. When equipped with a high-power amplifier and operating with a low-level modulation (BPSK or QPSK, for example), WiMAX systems are able to cover a large geographic area when the path between the BS and the SS is unobstructed.

•Non-Line-of-Sight Operation: NLOS usually refers to a radio path with its first Fresnel zone completely blocked. WiMAX is based on OFDM technology, which has the inherent capability of handling NLOS environments. This capability helps WiMAX products deliver broad bandwidth in a NLOS environment, which other wireless product cannot do.
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PRESENTED BY
A.V.NagaChary


.ppt   Wimax.ppt (Size: 1.25 MB / Downloads: 56)
WIMAX
INTRODUCTION
 WiMAX stands for Worldwide Interoperability of Microwave Access.
 WiMAX will offer broadband wireless access at data rates of multiple Mbit/s to the end-user and within a range of several kilometers
 WiMAX is described in IEEE 802.16 Wireless Metropolitan Area Network (MAN) standard.
 WiMAX has been developed to replace broadband cable networks and to enable mobile broadband wireless access.
Standards Associated With WIMAX
IEEE 802.16:
 The IEEE 802.16 Working Group on Broadband Wireless Access Standards, which was established by IEEE Standards Board which, aims to prepare broadband Wireless Metropolitan Area Networks.
Range:
 The wide range of the WiMAX technology depends on the height of the antennas, if they are installed at the suitable position from where there is no barrier between the transmitter and receiver, and then we can get better range and service from it.
Data Rates
 The technology used for WiMAX is Orthogonal Frequency Division Multiplexing (OFDM).
Cost:
 The network costs of WiMAX will be likely to be higher than for 3G because of the reduced range and hence the necessity to build more cells.
 The subscriber subsidy costs may be lower if WiMAX is built into processor chips.
Timing:
 It is normally believed that WiMAX will enter into the market some five years after 3G is well established.
WIMAX DESIGN
 The design of the WiMAX is related with wired and wireless access networks.
 backhaul connects the WiMAX system to the network, it is not an integrated part of WiMAX system.
Backhaul:
o 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.
o It is also possible to connect several base stations with one another by use of high speed backhaul microware links.
 Receiver
 A WiMAX receiver, which is also referred as Customer Premise Equipment (CPE), may have a separate antenna or could be a stand-alone box or a PCMCIA card that inserted in a laptop or a desktop computer.
TYPES OF WIMAX
 The WiMAX family of standards concentrate on two types of usage models a fixed usage model and a mobile usage model.
 Fixed Wimax
IEEE 802.16 standards provide advanced physical (PHY) layer techniques to achieve link margins capable of supporting high throughput in NLOS environments.
 Mobile Wimax
The 802.16a extension uses a lower frequency of 2 to 11 GHz, enabling NLOS connections.
WIMAX SERVICES
1.Potential Services
 Interactive Services
 Streaming Services
 Back Ground Servies
2.Current Service
FUTURE OF WIMAX
 It is expected that WiMAX technology will be incorporated in notebook computers and allowing for urban areas and cities to become "metro zones" for portable outdoor broadband wireless access.
 IEEE 802.16f and IEEE 802.16g task groups are addressing the management interfaces for fixed and mobile operation.
 All of these improvements will help make WiMAX an even better Internet access solution for growing economies like that of India.
CONCLUSION
 When WiMAX chipsets are integrated into laptops and other portable devices, it will provide high-speed data services.
 WiMAX has been developed to replace broadband cable networks and to enable mobile broadband wireless access.
 WiMAX will support seamless mobility and technologies such as the technique for minimized power consumption of the terminal, fast link adaptation.
 Providing data and telecommunications services.
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