WiMAX technology

WiMAX TECHNOLOGY

A SEMINAR REPORT

Submitted by

ATUL KUMAR

in partial fulfillment for the award of the degree

of

B-TECH DEGREE

in

COMPUTER SCIENCE & ENGINEERING

SCHOOL OF ENGINEERING

COCHIN UNIVERSITY OF SCIENCE & TECHNOLOGY

KOCHI- 682022

SEPTEMBER 2010

Division of Computer Engineering

School of Engineering

Cochin University of Science & Technology Kochi-682022

CERTIFICATE

Certified that this is a bonafide record of the seminar work titled

WiMAX Technology

Done by

Atul Kumar

of VII semester Computer Science & Engineering in the year 2010 in partial

fulfillment of the requirements for the award of Degree of Bachelor of Technology

in Computer Science & Engineering of Cochin University of Science & Technology

Dr.David Peter S Mr. Pramod Pavithran Head of the Division Seminar Guide

ACKNOWLEDGEMENT

I consider it as a great privilege to express my heartfelt gratitude to many

respected personalities who guided, inspired and helped me in successful

completion of this seminar.

I also express my gratitude to my seminar guide Mr. Pramod Pavithran,

Reader of Division of Computer Engineering and Mr. Sudheep Elayidom M,

seminar coordinator for providing me with adequate facilities, ways and means

by which I was able to complete this seminar. I express my sincere gratitude for

his constant support and valuable suggestions without which the successful

completion of this seminar would not have been possible.

I express my immense pleasure and thankfulness to all the teachers and staff of

the Division of Computer Engineering, CUSAT for their co-operation and

support.

Last but not the least, we thank all others, and especially our classmates who in

one way or another helped me in the successful completion of this seminar.

ATUL KUMAR

Reg. No.-12080017

CS-A, S7

ABSTRACT

Imagine a single wireless technology that can:

• make portable Internet a reality by extending public WLAN hotspots to

metropolitan area coverage for mobile data-centric service delivery,

• connect enterprises and residential users in urban and suburban

environments where access to copper plant is difficult,

• bridge the digital divide by delivering broadband in low-density areas.

Thanks to its innovative technology, WiMAX will offer broadband wireless

access at data rates of multiple Mbit/s to the end-user and within a range of

several kilometers. The same radio technology will also offer high-speed

data services to all nomadic terminals (laptops, PDAs, etc.) with an

optimized trade off between throughput and coverage. Ultimately it will

enable the "Portable Internet" usage replicating on the move the same user

experience as at home or at the office.

Given its huge benefits, WiMAX will develop as a powerful radio access

solution with many integration synergies in mobile or fixed network

architecture. WiMAX will also enable end-users to benefit from an "Always

Best Connected" experience when accessing their applications via the best

available network, at home, on the pause, or on the move. WiMAX

particularly fits in Alcatel's vision for a User-Centric Broadband World in

full complementarity with the other broadband access technologies: from

ADSL to UMTS and their evolutions towards higher speed and data

efficiency

ii

Table of Contents

Chapter

No.

Title

Page

No.

1 Introduction 1

2 What is Wimax? 2

2.1 Standards associated with Wimax 3

3 Why Wimax? 8

4 Wimax Technology 9

4.1 Technological Features 9

4.2 Technology Wimax Design 11

4.3 Types of Wimax 13

5 Wimax Technology Challenge 15

6 Enhancements in Wimax 18 7 Wimax a complement to fixed and mobile access 22

8 Wimax spectrum and regulation issues 26

9 Wimax services 31

10 Relationship with different wireless technolies 34

11 Wimax in INDIA 35

12 Conclusion 39

13 References 40

List of figures Sl.

No.

Images Page

No.

2.1 Wireless Standards 3

2.2 Types of 802.16 4

3.1 Data Rates 7

4.1 Radio Access Requirements 9

4.2 Wimax Tower 13

6.1 OFDM 18

9.1 Services 1 31

9.2 Services 2 33

WIMAX

Division of Computer Engineering 1

CHAPTER 1

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.

WIMAX


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.

WIMAX


• 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.

WIMAX

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


WIMAX

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.

2.2 Types 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.


WIMAX


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).

WIMAX


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 projected 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

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


WIMAX


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

WIMAX

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


WIMAX


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

WIMAX


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

WIMAX


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

WIMAX


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.

WIMAX

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


WIMAX


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.

WIMAX


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

WIMAX


(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

WIMAX


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

WIMAX

6 ENHANCEMENTS IN WIMAX

OFDM

OFDM stands for Orthogonal Frequency Division Multiplexing; it’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


WIMAX


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.

WIMAX


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 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

CPE and the possible interference with other base stations. For Line-of-Sight (LOS)

WIMAX


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.

WIMAX


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

WIMAX


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

WIMAX


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.

WIMAX


• 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.

WIMAX


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

WIMAX


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”

WIMAX


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 subscriber 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.

WIMAX


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 developers

WIMAX


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.

WIMAX

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


WIMAX

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 Samsung’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


WIMAX

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.


WIMAX


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.

WIMAX


CHAPTER 10

RELATIONSHIP WITH DIFFERENT WIRELESS

TECHNOLOGIES

3G Wi-Fi

802.11

WiMax

802.16

Mobile-Fi

802.20

Max Speed 2 Mbps 54 Mbps 100 Mbps 16 Mbps

Coverage Several miles 300 feet 50 miles Several miles

Airwave Licensed Unlicensed Either Licensed

Advantage Range

,mobility

Speed

,price

Speed

,range

Speed

,mobility

Disadvantagges Slow

,expensive

Short range Interference

issues?

High price

WIMAX


CHAPTER 11

WIMAX IN INDIA

Overview: Widespread, Affordable Connectivity

Connectivity is vital to Indian business and society. Globalization and the Internet

have created rapid growth in information technology-related businesses in India.

Although only half a percent of the Indian population has residential Internet access

(4.7 million out of 1 billion people), India’s more than 9,000 Internet cafes can be

seen bustling with people everywhere in the Indian cities.These Internet services

provide a means for people to stay connected with their friends and family through e-

mail, audio or video chat, and to browse the Internet for job and academic

opportunities. While Indians are enthusiastic about the Internet, the lack of physical

connectivity or telecommunications infrastructure and the cost and lack of broadband

technologies are a big hindrance to more widespread adoption of the Internet. In fact,

14 percent of India’s 0.6 million villages still do not have a single public telephone.

But wireless technologies are beginning to offer reliable alternatives to fixed-line

access, offering the potential for widespread, affordable connectivity to every region,

village, and person in India.

The Promise of Wireless Internet Access

India is increasingly embracing wireless technologies. Cellular phones based on

various wireless technologies have revolutionized telecommunications in India. As

the growth of fixed-line subscribers has slowed over the past several years, cellular

usage has skyrocketed, nearly doubling in 2003 and growing by 159 percent so far in

2004, with 1.4 million new subscribers every month. But these cellular technologies

have not delivered broadband data connectivity to the households, due to both cost

and complexity. Yet India needs a way to provide widespread Internet access, access

that can usher in economic growth, better education and healthcare and improved

WIMAX


entertainment services as it has done elsewhere in the world. And the solution must

be wireless, to avoid the overwhelming cost and resources that would be required to

deploy countrywide fixed-line broadband Internet infrastructure.With widespread

wireless broadband facilities, the Indian information technology (IT) industry could

grow beyond a few cities, students in rural areas could videoconference with

educators across the country, and entertainment programs could be telecast to remote

areas along with Internet telephony services, using technologies like Voice over

Internet Protocol (VoIP). Improved communications could bring remote villages into

the world economy, information access could speed worker productivity, and faster

communication between producers and suppliers could fuel demand for Indian

products.

Improved Education, Health Care and Entertainment

With higher bandwidth and faster speeds, broadband Internet can make education

more accessible by delivering interactive distance education at a low cost. TRAI

reports that in Korea, the government provided training on PC and Internet usage for

low-income and disabled households with children. They also launched programs to

provide these families with heavily subsidized and sometimes free PCs. Over 55

percent of all educational documents are electronic at this point. Teachers in schools

have access to their own PCs with Internet connections, and are required to leverage

information and communication technologies as an integral part of their curriculum.5

In India, schools and libraries in rural or remote areas without wired infrastructure or

broadband services can be costeffectively connected to broadband using WiMAX.

Video conferencing tools can help students to study a variety of subjects with

educators who may not be able to commute to remote areas. Lecture classes from

urban schools and top universities can be broadcast to rural students, and the students

could use the broadband facilities of WiMAX for communicating with teachers and

with their remote classmates. The Indira Gandhi National Open University (IGNOU)

is already encouraging state governments and conventional universities to establish

distance learning programs, providing financial support and grants for programs and

WIMAX


facilitating development of multimedia materials for delivery through distance

learning programs,6 Other premier institutions such as the Birla Institute of

Technology and Science (BITS), Pilani, are already offering distance learning

programs through relationships with industry and development agencies. BITS

conducts off-campus degree programs as a means of continuing education for

employed professionals as part of the human resource development programs of

specific organizations at various off-campus centers.” BITS offerings include degree

programs in math, science and engineering, computer science, medical and

healthcare and other fields.

7 Extensive and reliable broadband Internet can help these Internet-based quality

distance education reach more people across the nation. Agriculture and health care

can also benefit from broadband services. High-resolution pictures or real-time

images of crop diseases can be transmitted to agricultural experts in a different

geographic location for immediate expert advice, thus containing the crop diseases

faster. Similarly, doctors can use real-time video conferencing to discuss patient

symptoms with faraway experts, thus providing faster and better care to the patients.

802.16 Driving Down Costs

LaBrecque estimates that there are over 2,400 wireless Internet service providers

(ISPs) in the United States, serving over 6,000 markets (ISP-Market, LLC

Broadband Wireless Access 2002). But they use expensive, proprietary equipment

that's not interoperable with equipment from other vendors. A lack of standards has

also limited the usefulness of the technology and made it hard for wireless broadband

access providers to be competitive and profitable. To combat these issues the 802.16

standard was conceived. 802.16 will provide definitive standards for a carrier-class

solution that can scale to support thousands of users with a single base station and

provide differentiated service levels. For example, a single base station sector can

provide enough data rate to simultaneously support more than 60 businesses with T1-

type connectivity and hundreds of homes with DSL-type connectivity.

WIMAX


The benefits of 802.16 are many: by enabling standards-based products with fewer

variants and larger volume production, it will drive the cost of equipment down, and

having standardized equipment will also encourage competition, making it possible

to buy from many sources. For areas poorly served by a wired infrastructure,

including many developing countries, 802.16 will be important both for its ease of

implementation and its low cost

The 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.

WIMAX


CHAPTER 12

CONCLUSION

The latest developments in the IEEE 802.16 group are driving a broadband wireless

access (r) evolution thanks to a standard with unique technical characteristics. In

parallel, the WiMAX forum, backed by industry leaders, helps the widespread

adoption of broadband wireless access by establishing a brand for the technology.

Initially, WiMAX will bridge the digital divide and thanks to competitive equipment

prices, the scope of WiMAX deployment will broaden to cover markets where the

low POTS penetration, high DSL unbundling costs, or poor copper quality have

acted as a brake on extensive high-speed Internet and voice over broadband.

WiMAX will reach its peak by making Portable Internet a reality. When WiMAX

chipsets are integrated into laptops and other portable devices, it will provide high-

speed data services on the move, extending today's limited coverage of public

WLAN to metropolitan areas. Integrated into new generation networks with seamless

roaming between various accesses, it will enable end users to enjoy an "Always Best

Connected" experience. The combination of these capabilities makes WiMAX

attractive for a wide diversity of people: fixed operators, mobile operators and

wireless ISPs, but also for many vertical markets and local authorities. Alcatel, the

worldwide broadband market leader with a market share in excess of 37%, is

committed to offer complete support across the entire investment and operational

cycle required for successful deployment of WiMAX services

WIMAX


CHAPTER 13

REFERENCES

1) www.ewh.ieee.org/r4/chicago/Yu-WiMAX.pdf

2) http://computer.howstuffworks.com/wimax.htm

3) www.wimaxforum.org

4) http://standards.ieee.org/catalog/olis/lanman.html