A

Seminar Report

On

WiMAX

ENGINEERING COLLEGE BIKANER

Submitted in partial fulfillment of

BACHELOR OF TECHNOLOGY

2010-2011

Submitted By:-

ASHISH SONI

Final Year, CSE

07EEBCS021

Submitted To:-

MISS CHANDRIKA YOGI

ASST. PROFESSOR

DEPARMENT OF COMPUTER SCIENCE ENGINEERING

ENGINEERING COLLEGE BIKANER

(An Autonomous Institute of Govt. of Rajasthan)

ACKNOWLEDGEMENT

I express my sincere thanks to my seminar guide Miss Chandrika Yogi, ASST.

PROFESSOR C.S.E. Department, for their proper guidance, and valuable suggestions.

I sincerely acknowledge her for extending her valuable guidance, support for

literature, critical reviews of the topics and the report above all the moral support that

she provided me with all stages of this seminar.

I am indebted to Miss Chandrika Yogi, ASST. PROFESSOR, Computer Science

Engineering Department & other faculty members for giving me an opportunity to

learn and do this project. With the help of above mentioned people my seminar has

been completed successfully. I once again extend my sincere thanks to all of them.

ASHISH SONI

Computer Science

Final Year

PREFACE

Computer programming is an art. It is a way of explaining how a specific task is to be

performed by a given computer driven by speedy development in the underlying

hardware; compiler programs have become considerably complex and bigger.

Contrary to popular belief computer programming can be both fun & and excellent

opportunity to exercise your mind, creativity and imagination. It gives us the power to

instruct computers according to our will. With highly powerful work horses at

disposal, there is no limit to what we can do with the help of programming languages.

The only limit being our own imagination.

ABSTRACT

Within the last two decades, communication advances have reshaped the way we live

our daily lives. Wireless communications has grown from an obscure, unknown

service to an ubiquitous technology that serves almost half of the people on Earth.

Whether we know it or not, computers now play a dominant role in our daily

activities, and the Internet has completely reoriented the way people work,

communicate, play, and learn. However severe the changes in our lifestyle may seem

to have been over the past few years, the convergence of wireless with the Internet is

about to unleash a change so dramatic that soon wireless ubiquity will become as

pervasive as paper and pen. WiMax— which stands for Worldwide Interoperability

for Microwave Access—is about to bring the wireless and Internet revolutions to

portable devices across the globe. Just as broadcast television in the 1940’s and 1950’s

changed the world of entertainment, advertising, and our social fabric, WiMax is

poised to broadcast the Internet throughout the world, and the changes in our lives will

be dramatic. In a few years, WiMax will provide the capabilities of the Internet,

without any wires, to every living room, portable computer, phone, and handheld

device. In its simplest form, WiMax promises to deliver the Internet throughout the

globe, connecting the ―last mile‖ of communications services for both developed and

emerging nations.

INDEX

CHAPTER NO. PAGE NO.

CHAPTER-1 INTRODUCTION 1-6

1.1 Introduction…………………………………………………………………. …………..… 1

1.2 Necessity…………………………………………………………………………………..…3

1.3 Objectives…………………………………………………………………………….…….. 4

CHAPTER-2 SYSTEM DEVELOPMENT 7-8

2.1. IEEE 802.16 ……………………………………………………………………………….7

2.2.WiMax VS. WiFi ……………………………………………………………………………8

CHAPTER-3 WHAT IS WiMax 9-12

3.1.What is WiMax……………………………………………………………………………… 9

3.2. WiMAX Spectrum — Licensed and Unlicensed …………………………………………..10

3.3. Wireless Services………………………………………………………………………….. 11

CHAPTER-4 WiMax INFRASTRUCTURE 13-15

4.1 WiMax network has the following major features………………………………………… 13

4.2 Support for Services and Applications…………………………………………………….. 15

CHAPTER-5 Mobile WiMax 16-19

5.1 Introduction …………………………………………………………………………………16

5.2 OFDMA Basics …………………………………………………..........................................17

5.3 TDD Frame Structure………………………………………………………………………. 18

5.4. Mobility Management ……………………………………………………………………...18

CHAPTER-6 Advanced Features of WiMax 20-22

6.1 Smart Antenna Technologies………………………………………………………………. 20

6.2 Fractional Frequency Reuse ………………………………………………………………...21

6.3 Multicast and Broadcast Service (MBS)…………………………………………………… 22

CHAPTER-7 WiMAX versus 3G and Wi-Fi 23-24

CHAPTER-8 Applications of Wimax 25-26

CHAPTER- 9 CONCLUSIONS 27-28

LIST OF ACRONYMS 29-30

REFERENCES 31

LISTOF FIGURES

FIGURE NO. PAGE NO.

Figure 1.1 Worldwide subscriber growth for mobile telephony………………………………… 2

Figure 1.2 Objectives of WiMax………………………………………………………………... 4

Figure 3.1 WiMax Overview……………………………………………………………………. 9

Figure 3.2 Working of WiMax …………………………………………………………………12

Figure 6.1 Fractional Frequency Reuse………………………………………………………... 21

Figure 7.1 Comparison of wireless technologies………………………………………………. 24

Figure 8.1 IPTV Server………………………………………………………………………… 25

Chapter – 1

INTRODUCTION

1.1 Introduction

Broadband wireless sits at the confluence of two of the most remarkable growth stories of the

telecommunications industry in recent years. Both wireless and broadband have on their own

enjoyed rapid mass-market adoption. Wireless mobile services grew from 11 million subscribers

worldwide in 1990 to more than 2 billion in 2005 . During the same period, the Internet grew from

being a curious academic tool to having about a billion users. This staggering growth of the Internet

is driving demand for higher-speed Internet-access services, leading to a parallel growth in

broadband adoption. In less than a decade, broadband subscription worldwide has grown from

virtually zero to over 200 million. Will combining the convenience of wireless with the rich

performance of broadband be the next frontier for growth in the industry? Can such a combination

be technically and commercially viable? Can wireless deliver broadband applications and services

that are of interest to the end-users? Many industry observers believe so. Before we delve into

broadband wireless, let us review the state of broadband access today. Digital subscriber line (DSL)

technology, which delivers broadband over twisted-pair telephone wires, and cable modem

technology, which delivers over coaxial cable TV plant, is the predominant mass-market broadband

access technologies today. Both of these technologies typically provide up to a few megabits per

second of data to each user, and continuing advances are making several tens of megabits per second

possible. Since their initial deployment in the late 1990s, these services have enjoyed considerable

growth. The United States has more than 50 million broadband subscribers, including more than half

of home Internet users. Worldwide, this number is more than 200 million today and is projected to

grow to more than 400 million by 2010. The availability of a wireless solution for broadband could

potentially accelerate this growth. What are the applications that drive this growth?\Broadband users

worldwide are finding that it dramatically changes how we share information, conduct business, and

seek entertainment. Broadband access not only provides faster Web surfing and quicker file

downloads but also enables several multimedia applications, such as real-time audio and video

streaming, multimedia conferencing, and interactive gaming. Broadband connections are also being

used for voice telephony using voice-over-Internet Protocol (VoIP) technology.

Figure 1.1 Worldwide subscriber growth 1990–2006 for mobile telephony, Internet

usage, and broadband access

More advanced broadband access systems, such as fiber-to-the-home (FTTH) and very high data rate

digital subscriber loop (VDSL), enable such applications as entertainmentquality video, including

high-definition TV (HDTV) and video on demand (VoD). As the broadband market continues to

grow, several new applications are likely to emerge, and it is difficult to predict which ones will

succeed in the future. So what is broadband wireless? Broadband wireless is about bringing the

broadband experience to a wireless context, which offers users certain unique benefits and

convenience. There are two fundamentally different types of broadband wireless services. The first

type attempts to provide a set of services similar to that of the traditional fixedline broadband but

using wireless as the medium of transmission. This type, called fixed wireless broadband, can be

thought of as a competitive alternative to DSL or cable modem. The second type of broadband

wireless, called mobile broadband, offers the additional functionality of portability, nomadicity,1

and mobility. Mobile broadband attempts to bring broadband applications to new user experience

scenarios and hence can offer the end user a very different value proposition. WiMax (worldwide

interoperability for microwave access) technology.

1.2 Necessity

In many parts of the world, existing fixed-line carriers that do not own cellular, PCS, or 3G

spectrums could turn to WiMax for provisioning mobility services. As the industry moves along the

path of quadruple-play service bundles—voice, data, video, and mobility —some service providers

that do not have a mobility component in their portfolios—cable operators, satellite companies, and

incumbent phone companies—are likely to find WiMax attractive. For many of these companies,

having a mobility plan will be not only a new revenue opportunity but also a defensive play to

mitigate churn by enhancing the value of their product set.

Existing mobile operators are less likely to adopt WiMax and more likely to continue along the path

of 3G evolution for higher data rate capabilities. There may be scenarios, however, in which

traditional mobile operators may deploy WiMax as an overlay solution to provide even higher data

rates in targeted urban centers or metro zones. In addition to higher-speed Internet access, mobile

WiMax can be used to provide voiceover- IP services in the future. The low-latency design of

mobile WiMax makes it possible to deliver VoIP services effectively. VoIP technologies may also

be leveraged to provide innovative new services, such as voice chatting, push-to-talk, and

multimedia chatting. New and existing operators may also attempt to use WiMax to offer

differentiated personal broadband services, such as mobile entertainment. The flexible channel

bandwidths and multiple levels of quality-of-service (QoS) support may allow WiMax to be used by

service providers for differentiated high-bandwidth and low-latency entertainment applications. For

example, WiMax could be embedded into a portable gaming device for use in a fixed and mobile

environment for interactive gaming. Other examples would be streaming audio services delivered to

MP3 players and video services delivered to portable media players. As traditional telephone

companies move into the entertainment area with IP-TV (Internet Protocol television), portable

WiMAX could be used as a solution to extend applications and content beyond the home.

1.3 Objectives

The WiMax standard has been developed with many objectives in mind. These are

summarized below:

Fig 1.2 Objectives of WiMax

Flexible Architecture: WiMax supports several system architectures, including Point-to-

Point, Point-to-Multipoint 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.

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 SLA s 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 Scalable

OFDMA, MIMO, and support for idle/sleep mode and hand-off, will allow full mobility at

speeds up to 160 km/hr.

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 highpower 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.

High Capacity: Using higher modulation (64-QAM) and channel bandwidth(currently 7

MHz, with planned evolution towards the full bandwidth specified in the standards), WiMax

systems can provide significant.

Chapter – 2

SYSTEM DEVELOPMENT

2.1. IEEE 802.16

The IEEE 802.16 Working Group is the IEEE group for wireless metropolitan area network. The

IEEE 802.16 standard defines the Wireless MAN (metropolitan area network) air interface

specification (officially known as the IEEE Wireless MAN standard). This wireless broadband

access standard could supply the missing link for the ―last mile‖ connection in wireless metropolitan

area networks. Wireless broadband access is set up like cellular systems, using base stations that

service a radius of several miles/kilometers. Base stations do not necessarily have to reside on a

tower. More often than not, the base station antenna will be located on a rooftop of a tall building or

other elevated structure such as a grain silo or water tower. A customer premise unit, similar to a

satellite TV setup, is all it takes to connect the base station to a customer. The signal is then routed

via 89standard Ethernet cable either directly to a single computer, or to an 802.11hot spot or a wired

Ethernet LAN. The IEEE 802.16 designed to operate in the 10-66 GHz spectrum and it specifies the

physical layer (PHY) and medium access control layer (MAC) of the air interface BWA systems. At

10-66 GHz range, transmission requires Line-of-Sight (LOS).IEEE 802.16 is working group number

16 of IEEE 802, specializing in point-to-multipoint broadband wireless access.

The IEEE 802.16 standard provides the foundation for a wireless MAN industry. However, the

physical layer is not suitable for lower frequency applications where nonline- of-sight (NLOS)

operation is required. For this reason, the IEEE published 802.16a standard to accommodate NLOS

requirement in April 2003. The standard operates in licensed and unlicensed frequencies between 2

GHz and 11 GHz, and it is an extension of the IEEE 802.16standard.The IEEE 802.16 Working

Group created a new standard, commonly known as WiMax, for broadband wireless access at high

speed and low cost, which is easy to deploy, and which provides a scalable solution for extension of

a fiber-optic backbone.

WiMax base stations can offer greater wireless coverage of about 5 miles, with LOS (line

of sight) transmission within bandwidth of up to 70 Mbps.

DSL and cable in areas where those technologies are readily available.

2.2. WiMax VS. WiFi

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 megabits

per second under optimal conditions. WiMAX should be able to handle up to 70 megabits per

second. Even once that70 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.

WiMax is not designed to clash with WiFi, but to coexist with it. WiMax coverage

is measured in square kilometers, while that of WiFi is measured in square meters. The original

WiMax standard (IEEE 802.16) proposes the usage of 10-66 GHz frequency spectrum for the

WiMax transmission, which is well above the WiFi range (up to 5GHz maximum). But 802.16a

added support for 2-11 GHz frequency also. One WiMax base station can be accessed by more than

60 users. WiMax can also provide broadcasting services also. WiMax specifications also provides

much better facilities than WiFi, providing higher bandwidth and high data security by the use of

enhanced encryption schemes. WiMax can also provide service in both Line Of Sight (LOS) and

Non-Line Of Sight (NLOS) locations, but the range will vary accordingly. WiMax will allow the

interpenetration for broadband service provision of VoIP, video, and internet access –

simultaneously. WiMax can also work with existing mobile networks. WiMax antennas can "share"

a cell tower without compromising the function of cellular arrays already in place.

Chapter-3

What is WiMax

3.1.What is WiMax

Worldwide Interoperability for Microwave Access (WiMAX) is currently one of the hottest

technologies in wireless. The WiMAX Forum has adopted certain profiles based on the 802.16

standards for interoperability testing and ―WiMAX certification‖. These operate in the 2.5GHz,

3.5GHz and 5.8GHz frequency bands, which typically are licensed by various government

authorities. WiMAX, is based on an RF technology called Orthogonal Frequency Division

Multiplexing (OFDM), which is a very effective means of transferring data when carriers of width of

5MHz or greater can be used. Below 5MHz carrier width, current CDMA based 3G systems are

comparable to OFDM in terms of performance.

WiMAX is a standard-based wireless technology that provides high throughput

broadband connections over long distance. WiMAX can be used for a number of applications,

including ―last mile‖ broadband connections, hotspots and high-speed connectivity for business

customers. It provides wireless metropolitan area network (MAN) connectivity at speeds up to

70 Mbps and the WiMAX base station on the average can cover between 5 to 10 km.

Figure 3.1. WiMAX Overview.

3.2. WiMax Spectrum — Licensed and Unlicensed

As with any other spectrum based technology, successful WiMAX deployment will depend largely

upon the availability and suitability of spectrum resources. For entities providing wireless

communications services, two sources of spectrum are available:

Licensed spectrum and

Unlicensed spectrum.

Licensed spectrum requires an authorization/license from the Commission, which offers that

individual user or ―Licensee‖ the exclusive rights to operate on a specific frequency (or frequencies)

at a particular location or within a defined geographic area. In contrast, unlicensed spectrum permits

any user to access specific frequencies within any geographic area inside the United States without

prior Commission authorization. While users of this spectrum do not have to apply for individual

licenses or pay to use the spectrum, they are still subject to certain rules. First, unlicensed users must

not cause interference to licensed users and must accept any interference they receive. Second, any

equipment that will be utilized on unlicensed spectrum must be approved in advance by the

Commission. Because of its broad operating range, licensed and unlicensed spectrum options for

WiMax technology are extensive. To take best advantage of the benefits provided by WiMax

systems, large block spectrum assignments are most desirable. This enables systems to be deployed

in TDD mode with large channel bandwidths, flexible frequency re-use and with minimal spectral

inefficiencies for guard-bands to facilitate coexistence with adjacent operators. Another key activity

for the WiMax Forum is collaborating with standards and regulatory bodies worldwide to promote

the allocation of spectrum in the lower frequency bands (< 6 GHz) that is both application and

technology neutral. Additionally, there is a major push for greater harmonization in spectrum

allocations so as to minimize the number equipment variants required to cover worldwide The initial

system performance profiles that will be developed by the WiMax Forum for the recently approved

802.16-2005 air interface standard are expected to be in the licensed 2.3 GHz, 2.5 GHz and 3.5 GHz

frequency bands. The 2.3 GHz band has been allocated in South Korea for WiBro services based on

the Mobile WiMax technology. With a 27 MHz block of spectrum assignment to each operator, this

band will support a TDD deployment with 3 channels per base station and a nominal channel

bandwidth of 8.75 MHz. The 2.5 to 2.7 GHz band is already available for mobile and fixed wireless

services in the United States. This band is also currently underutilized and potentially available in

many countries throughout South America and Europe as well as some countries in the Asia-Pacific

region. The 3.5 GHz band is already allocated for fixed wireless services in many countries

worldwide and is also well-suited to WiMax solutions for both fixed and mobile services.

3.3. Wireless Services

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 subscriber

computer connects to the tower. In this mode, WiMAX uses a lower frequency range 2GHz

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.

Figure 3.2Working of WiMax

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, s \ 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.

.

Chapter-4

WiMax Infrastructure

Typically, a WiMax system consists of two parts:

A WiMax Base Station- Base station consists of indoor electronics and a WiMax tower.

Typically, a base station can cover up to 10 km radius (Theoretically, a base station can

cover-up to 50 kilo meter radius or 30 miles, however practical considerations limit it to

about 10km or 6 miles). Any wireless node within the coverage area would be able to access

the Internet.

A WiMax receiver - The receiver and antenna could be a stand-alone box or a PC card that

sits in your laptop or computer. Access to WiMax base station is similar to accessing a

Wireless Access Point in a WiFi network, but the coverage is more. Several base stations can

be connected with one another by use of high-speed backhaul microwave links. This would

allow for roaming by a WiMax subscriber from one base station to another base station area,

similar to roaming enabled by Cellular phone companies. Several topology and backhauling

options are to be supported on the WiMax base stations wire line backhauling (typically over

Ethernet), microwave Point-to-Point connection, as well as WiMax backhaul. With the latter

option, the base 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.

4.1 WiMax network has the following major features:

Security. The end-to-end WiMax Network Architecture is based on a security framework

that is agnostic to the operator type and ASN topology and applies consistently across

Greenfield and internetworking deployment models and usage scenarios. In particular there is

support for:

1. Strong mutual device authentication between an MS and the WiMax

2. All commonly deployed authentication mechanisms and authentication in home and

visited operator network scenarios based on a consistent and extensible authentication framework

3. Data integrity, replay protection, confidentiality and non-repudiation using applicable key lengths,

4. Use of MS initiated/terminated security mechanisms such as Virtual Private Networks (VPNs),

5. Standard secure IP address management mechanisms between the MS/SS and its home or visited

NSP.

Mobility and Handovers. The end-to-end WiMax Network Architecture has extensive

capability to support mobility and handovers. It will:

1. Include vertical or inter-technology handovers— e.g., to Wi-Fi, 3GPP (The Third Generation

Partnership Project) , 3GPP2, DSL, or MSO (Multiple Service Operators) – when such capability is

enabled in multi-mode MS,

2. Support IPv4 (IP Version 4) or IPv6 based mobility management. Within this framework, and as

applicable, the architecture shall accommodate MS with multiple IP addresses and simultaneous

IPv4 and IPv6 connections,

3. Support roaming between NSPs,

4. Utilize mechanisms to support seamless handovers at up to vehicular speeds— satisfying well

defined (within WiMax Forum) bounds of service disruption.

Some of the additional capabilities in support of mobility include the support of:

1. Dynamic and static home address configurations,

2. Dynamic assignment of the Home Agent in the service provider network as a form of route

optimization, as well as in the home IP network as a form of load balancing

3. Dynamic assignment of the Home Agent based on policies.

Quality of Service. The WiMax Network Architecture has provisions for support of QoS

mechanisms. In particular, it enables flexible support of simultaneous use of a diverse set of

IP services. The architecture supports:

1. Differentiated levels of QoS - coarse-grained (per user/terminal) and/or finegrained

(per service flow per user/terminal),

2. Admission control, and

3. Bandwidth management Extensive use is made of standard IETF mechanisms for

managing policy definition and policy enforcement between operators.

4.2. Support for Services and Applications. The end-to-end architecture includes the

support for:

Voice, multimedia services and other mandated regulatory services such as emergency

services and lawful interception,

Access to a variety of independent Application Service Provider (ASP) networks in an

agnostic manner,

Mobile telephony communications using VoIP,

Support interfacing with various interworking and media gateways permitting delivery of

incumbent/legacy services translated over IP (for example, SMS over IP, MMS, WAP) to

WiMax access networks and

Support delivery of IP Broadcast and Multicast services over WiMax access networks.

Chapter-5

Mobile WiMax

5.1 Introduction

The WiMax technology, based on the IEEE 802.16-2004 Air Interface Standard is rapidly proving

itself as a technology that will play a key role in fixed broadband wireless metropolitan area

networks. The first certification lab, established at Cetecom Labs in Malaga, Spain is fully

operational and more than 150 WiMax trials are underway in Europe, Asia, Africa and North and

South America. Unquestionably, Fixed WiMax, based on the IEEE 802.16-2004 Air Interface

Standard, has proven to be a cost-effective fixed wireless alternative to cable and DSL services. In

December, 2005 the IEEE ratified the 802.16e amendment to the 802.16 standard. This amendment

adds the features and attributes to the standard that is necessary to support mobility. The WiMax

Forum is now defining system\ performance and certification profiles based on the IEEE 802.16e

Mobile Amendment and, going beyond the air interface, the WiMax Forum is defining the network

architecture necessary for implementing an end-to-end Mobile WiMax2 network. Release-1 system

profiles were completed in early 2006.

Mobile WiMax is a broadband wireless solution that enables convergence of

mobile and fixed broadband networks through a common wide area broadband radio access

technology and flexible network architecture. The Mobile WiMax Air Interface adopts Orthogonal

Frequency Division Multiple Access (OFDMA) for improved multi-path performance in non line-of-

sight environments. Scalable OFDMA (SOFDMA) is introduced in the IEEE 802.16eAmendment to

support scalable channel bandwidths from 1.25 to 20 MHz.

WiMax profiles will cover 5,7, 8.75, and 10 MHz channel bandwidths for licensed worldwide

spectrum allocations in the2.3 GHz, 2.5 GHz, and 3.5 GHz frequency bands. Mobile WiMax

systems offer scalability in both radio access technology and network architecture, thus providing a

great deal of flexibility in network deployment options and service offerings. Some of the salient

features supported by Mobile WiMax are:

High Data Rates. The inclusion of MIMO (Multiple Input Multiple Output) antenna

techniques along with flexible sub-channelization schemes, Advanced Coding and

Modulation all enable the Mobile WiMax technology to support peak DL data rates up to

63Mbps per sector and peak UL data rates up to 28 Mbps per sector in a 10 MHz channel.

Quality of Service (QoS). The fundamental premise of the IEEE 802.16 MAC architecture

is QoS. It defines Service Flows which can map to Diff Serv code points that enable end-to

end IP based QoS. Additionally, sub channelization schemes provide a flexible mechanism

for optimal scheduling of space, frequency and time resources over the air interface on a

frame by-frame basis.

Scalability. Despite an increasingly globalize economy, spectrum resources for wireless

broadband worldwide are still quite disparate in its allocations. Mobile WiMax technology

therefore, is designed to be able to scale to work in different canalizations from 1.25 to 20

MHz to comply with varied worldwide requirements as efforts proceed to achieve spectrum

harmonization in the longer term. This also allows diverse economies to realize the

multifaceted benefits of the Mobile WiMax technology for their specific geographic needs

such as providing affordable internet access in rural settings versus enhancing the capacity of

mobile broadband access in metro and suburban areas.

Security. Support for a diverse set of user credentials exists including; SIM/USIM cards,

Smart Cards, Digital Certificates, and Username/Password schemes.

Mobility. Mobile WiMax supports optimized handover schemes with latencies less than

50milliseconds to ensure real-time applications such as VoIP perform without service

degradation. Flexible key management schemes assure that security is maintained during

handover.

5.2 OFDMA Basics

Orthogonal Frequency Division Multiplexing (OFDM) is a multiplexing technique that subdivides

the bandwidth into multiple frequency sub-carriers as shown in Figure In an OFDM system, the

input data stream is divided into several parallel sub-streams of reduced data rate (thus increased

symbol duration) and each sub-stream is modulated and transmitted on a separate orthogonal sub-

carrier. The increased symbol duration improves the robustness of OFDM to delay spread.

Furthermore, the introduction of the cyclic prefix (CP) can completely eliminate Inter-Symbol

Interference (ISI) as long as the CP duration is longer than the channel delay spread. The CP is

typically a repetition of the last samples of data portion of the block that is appended to the

beginning of the data payload as shown The CP prevents inter-block interference and makes the

channel appear circular and permits low complexity frequency domain equalization. A perceived

drawback of CP is that it introduces overhead, which effectively reduces bandwidth efficiency.

While the CP does reduce bandwidth efficiency somewhat, the impact of the CP is similar to the

―rolloff factor‖ in raised-cosine filtered single-carrier systems. Since OFDM has a very sharp, almost

―brick wall‖ spectrum, a large fraction of the allocated channel bandwidth can be utilized for data

transmission, which helps to moderate the loss in efficiency due to the cyclic prefix.

5.3 TDD Frame Structure

The 802.16e PHY supports TDD, FDD, and Half-Duplex FDD operation; however the initial release

of Mobile WiMax certification profiles will only include TDD. With ongoing releases, FDD profiles

will be considered by the WiMax Forum to address specific market opportunities where local

spectrum regulatory requirements either prohibit TDD or are more suitable for FDD deployments.

To counter interference issues, TDD does require system-wide synchronization; nevertheless, TDD

is the preferred duplexing mode for the following reasons:

TDD enables adjustment of the downlink/uplink ratio to efficiently support asymmetric

downlink/uplink traffic, while with FDD, downlink and uplink always have fixed and

generally, equal DL and UL bandwidths.

TDD assures channel reciprocity for better support of link adaptation, MIMO and other

closed loop advanced antenna technologies.

Unlike FDD, which requires a pair of channels, TDD only requires a single channel for both

downlink and uplink providing greater flexibility for adaptation to varied global spectrum

allocations.

Transceiver designs for TDD implementations are less complex and therefore less expensive.

5.4 Mobility Management

Battery life and handoff are two critical issues for mobile applications. Mobile WiMax supports

Sleep Mode and Idle Mode to enable power-efficient MS operation. Mobile WiMax also supports

seamless handoff to enable the MS to switch from one base station to another at vehicular speeds

without interrupting the connection.

Power Management. Mobile WiMax supports two modes for power efficient operation

Sleep Mode and Idle Mode. Sleep Mode is a state in which the MS conducts pre-negotiated

periods of absence from the Serving Base Station air interface. These periods are

characterized by the unavailability of the MS, as observed from the Serving Base Station, to

DL or UL traffic. Sleep Mode is intended to minimize MS power usage and minimize the

usage of the Serving Base Station air interface resources. The Sleep Mode also provides

flexibility for the MS to scan other base stations to collect information to assist handoff

during the Sleep Mode. Idle Mode provides a mechanism for the MS to become periodically

available for DL broadcast traffic messaging without registration at a specific base station as

the MS traverses an air link environment populated by multiple base stations. Idle Mode

benefits the MS by removing the requirement for handoff and other normal operations and

benefits the network and base station by eliminating air interface and network handoff traffic

from essentially inactive MSs while still providing a simple and timely method (paging) for

alerting the MS about pending DL traffic.

Handoff. The IEEE 802 Handoff Study Group, is another group chartered with addressing

roaming that studies hand-offs between heterogeneous 802 networks. The key here will be

enabling the ―hand-off‖ procedures that allow a mobile device to switch the connection from

one base station to another, from one 802 network type to another (such as from 802.11b to

802.16), and even from wired to 802.11 or 802.16 connections. The goal is to standardize the

hand-off so devices are interoperable as they move from one network type to another. Today,

802.11 users can move around a building or a hotspot and stay connected, but if they leave,

they lose their connection. With 802.16e, users will be able to stay ―best connected‖—

connected by 802.11 when they’re within a hot spot, and then connected to 802.16 when they

leave the hot spot but are within a WiMax service area. Furthermore, having a standard in

place opens the door to volume component suppliers that will allow equipment vendors to

focus on system design, versus having to develop the whole end-to-end solution. When

having either 802.16e capabilities embedded in a PDA or notebook (or added through an

802.16e-enabled card) user remain connected within an entire metropolitan

Chapter-6

Advanced Features of WiMax

An important and very challenging function of the WiMax system is the support of various advanced

antenna 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.

6.1 Smart Antenna Technologies

Smart antenna technologies typically involve complex vector or matrix operations on signals due to

multiple antennas. OFDMA allows smart antenna operations to be performed on vector-flat sub-

carriers. Complex equalizers are not required to compensate for frequency selective fading. OFDMA

therefore, is very well-suited to support smart antenna technologies. In fact, MIMO-OFDM/OFDMA

is envisioned as the corner-stone for next generation broadband communication systems. Mobile

WiMax supports a full range of smart antenna technologies to enhance system performance. The

smart antenna technologies supported include:

Beam forming. With beam forming, the system uses multiple-antennas to transmit weighted

signals to improve coverage and capacity of the system and reduce outage probability.

Spatial Multiplexing (SM). Spatial multiplexing is supported to take advantage of higher

peak rates and increased throughput. With spatial multiplexing, multiple streams are

transmitted over multiple antennas. If the receiver also has multiple antennas, it can separate

the different streams to achieve higher throughput compared to single antenna systems. With

2x2 MIMO, SM increases the peak data rate two-fold by transmitting two data streams. In

UL, each user has only one transmit antenna, two users can transmit collaboratively in the

same slot as if two streams are spatially multiplexed from two antennas of the same user.

6.2 Fractional Frequency Reuse

WiMax supports frequency reuse of one, i.e. all cells/sectors operate on the same frequency channel

to maximize spectral efficiency. However, due to heavy co channel interference (CCI) in frequency

reuse one deployment, users at the cell edge may suffer degradation in connection quality. Users can

operate on sub channels, which only occupy a small fraction of the whole channel bandwidth; the

cell edge interference problem can be easily addressed by appropriately configuring sub channel

usage without resorting to traditional frequency planning. The flexible sub-channel reuse is

facilitated

Figure 6.1. Fractional Frequency Reuse

by sub-channel segmentation and permutation zone. A segment is a subdivision of the available

OFDMA sub-channels (one segment may include all sub-channels). One segment is used for

deploying a single instance of MAC.

6.3. Multicast and Broadcast Service (MBS)

Multicast and Broadcast Service (MBS) supported by WiMax satisfy the following requirements:

High data rate and coverage using a Single Frequency Network (SFN)

Flexible allocation of radio resources

Low MS power consumption

Support of data-casting in addition to audio and video streams

Low channel switching time

Chapter – 7

WiMAX versus 3G and Wi-Fi

How does WiMAX compare with the existing and emerging capabilities of 3G and Wi-Fi? The

throughput capabilities of WiMax depend on the channel bandwidth used. Unlike 3G systems, which

have a fixed channel bandwidth, WiMax defines a selectable channel bandwidth from 1.25MHz to

20MHz, which allows for a very flexible deployment. When deployed using the more likely 10MHz

TDD (time division duplexing) channel, assuming a 3:1 downlink-to-uplink split, WiMax offers

46Mbps peak downlink throughput and 7Mbps uplink.

The reliance of Wi-Fi and WiMax on OFDM modulation, as opposed to CDMA as

in 3G, allows them to support very high peak rates. The need for spreading makes very high data

rates more difficult in CDMA systems. More important than peak data rate offered over an

individual link is the average throughput and overall system capacity when deployed in a

multicultural environment. From a capacity standpoint, the more pertinent measure of system

performance is spectral efficiency. WiMax specifications accommodated multiple antennas right

from the start gives it a boost in spectral efficiency. In 3G systems, on the other hand, multiple-

antenna support is being added in the form of revisions. Further, the OFDM physical layer used by

WiMax is more amenable to MIMO implementations than are CDMA systems from the standpoint

of the required complexity for comparable gain. OFDM also makes it easier to exploit frequency

diversity and multi-user diversity to improve capacity. Therefore, when compared to 3G, WiMax

offers higher peak data rates, greater flexibility, and higher average throughput and system capacity.

Another advantage of WiMax is its ability to efficiently support more symmetric links useful for

fixed applications, such as T1 replacement—and support for flexible and dynamic adjustment of the

downlink-to-uplink data rate ratios. Typically, 3G systems have a fixed asymmetric data rate ratio

between downlink and uplink what about in terms of supporting advanced IP applications, such as

voice, video, and multimedia?

How do the technologies compare in terms of prioritizing traffic and controlling

quality?

Figure7.1 Comparison of wireless technologies

In terms of supporting roaming and high-speed vehicular mobility, WiMAX capabilities are

somewhat unproven when compared to those of 3G. In 3G, mobility was an integral part of the

design; WiMax was designed as a fixed system, with mobility capabilities developed as an add-on

feature. In summary, WiMax occupies a somewhat middle ground between Wi-Fi and 3G

technologies when compared in the key dimensions of data rate, coverage, QoS, mobility, and price.

figure7.1 provides a summary comparison of WiMax with 3G and Wi-Fi technologies.

Chapter – 8

Applications of Wimax

1. WiMax& IPTV : The third leg of the triple play is Internet Protocol Television (IPTV). IPTV

enables a WiMax service provider to offer the same programming as cable or satellite TV service

providers. IPTV, depending on compression algorithms, requires at least 1 Mbps of bandwidth

between the WMAX base station and the subscriber.

In addition to IPTV programming, the service provider can also offer a variety of

video on demand (VoD) services. The subscriber can select programming a la carte for their

television, both home and mobile, viewing needs. This may be more desirable to the sub-scriber as

they pay only for what they want to watch as opposed to having to pay for dozens of channels they

don't want to watch. IPTV over WiMax also enables the service provider to offer local programming

as well as revenue generating local advertising.

Figure 8.1: IPTV and Video on Demand enable a WiMAX service provider to offer

programming identical to cable and satellite providers

2. WiMax as cellular alternative of all the sub industries in telecommunications, perhaps the one

best positioned to take advantage of WiMax is the cellular service providers. They have a lot going

for them including a wireless culture (RF engineers, wireless savvy sales staff, etc) and millions of

"early adaptor" customers. On the other hand, the transition from legacy circuit switching and a

dependency on the incumbent telephone service provider's network will not be easy or inexpensive

As the diagram below supports a large percentage of a cell phone operator's monthly operating

expense (OPEX) is T1 backhaul to support their base stations. In addition, they use aging circuit

switches (Class 4 and 5 as well as Mobile Switching Centers) to switch phone calls. These come

with expensive annual service contracts. A WiMax substitute for the cell phone infrastructure could

be operated at as little as 10% of the OPEX of a cellular operator using legacy infrastructure.

3. Source: Trendsmedia Replacing a cell phone infrastructure with WiMax will need to incorporate

a large mo-bile data and mobile TV element with it as data bandwidth demands on the system will

be far greater than what is now seen with a voice-centric cell phone network. The diagram below

provides a high overview of a converged voice and data wireless network. to come to mind is cell

phone service which is a huge industry in itself. However, mobile now connotes a wide range of

services be-yond voice to include mobile data and TV, as well as emergency services

Chapter – 9

CONCLUSION

WiMax offers benefits for wire line operators who want to provide last mile access to residences and

businesses, either to reduce costs in their own operating areas, or as a way to enter new markets.

802.16e offers cost reductions to mobile operators who wish to offer broadband IP services in

addition to 2G or 3G voice service, and allows operators to enter new markets with competitive

services, despite owning disadvantaged spectrum. The capital outlay for WiMAX equipment will be

less than for traditional 2G and 3G wireless networks, although the supporting infrastructure of cell

sites, civil works, towers and so on will still be needed. WiMax’s all-IP architecture lends itself well

to high bandwidth multimedia applications, and with QoS will also support mobile voice and

messaging services, re-using the mobile networks IP core systems.

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

revolution 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 with high DSL

unbundling costs or poor copper quality which 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 (Internet Service Provider),

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 is based on a very flexible and robust air interface defined by the IEEE 802.16 group.

• The WiMax physical layer is based on OFDM, which is an elegant and effective technique for

overcoming multipart distortion.

• WiMax supports a number of advanced signal-processing techniques to improve overall system

capacity. These techniques include adaptive modulation and coding, spatial multiplexing, and multi-

user diversity.

• WiMax has a very flexible MAC layer that can accommodate a variety of traffic types, Including

voice, video, and multimedia, and provide strong QoS.

• Robust security functions, such as strong encryption and mutual authentication, are built Into the

WiMax standard.

• WiMax has several features to enhance mobility-related functions such as seamless handover and

low power consumption for portable devices.

• WiMax offers very high spectral efficiency, particularly when using higher-order MIMO

solutions.

LIST OF ACRONYMS

ATM: Asynchronous Transfer Mode

BRAS: Broadband Remote Access Server

BS: Base Station

BWA: Broadband Wireless Access. Enabling high-speed broadband connections

the air instead of over wired (fixed) connections

CDMA: Code Division Multiple Access

DSL: Digital Subscriber Line

EUL: Enhanced Up Link,

FDD: Frequency Division Duplex

GPRS: General Packet Radio Service

GSM: Global System for Mobile communication

IEEE: Institution for Electrical and Electronics Engineers. Standardization body.

IMS: IP Multimedia Subsystem

IP: Internet Protocol

ITU: International Telecommunication Union.

LOS: Line-Of-Sight

MAC: Medium Access Control

MAN: Metropolitan Area Network

NLOS: Non-Line-Of-Sight

OFDM: Orthogonal Frequency Division Multiplexing

PHY: Physical Layer

PSTN: Public Switched Telephone Network

QoS: Quality of Service

RF: Radio Frequency

SIP: Simple Internet Protocol

SME: Small and Medium size Enterprises

SoHo: Small Office Home Office

SS: Subscriber Station

TDD: Time Division Duplex

TDM: Time Division Multiplexing

TDMA: Time-Division Multiple Access

Users: Consumers, presumes, end-users and subscribers

VoIP: Voice over Internet Protocol technology enables users to transmit voice calls via

the Internet using packet-linked routes.

WCDMA: Wideband Code Division Multiple Access

WiFi: Wireless Fidelity, or Wireless Local Area Network, WLAN

WiMAX: World-wide interoperability for Microwave Access

REFERENCES

1. IEEE. Standard 802.16.3c-01/29r4. Channel models for fixed wireless

Applications.www.ieee802.org/16.

2. T. S. Rappaport. Wireless Communications: Principles and Practice, 2nd ed.

3. www.efymagzine.co.in/WiMaxtechnology

4. www.wikipedia.en/wimaxintroduction