Mini Project Qos Analysis of WiMAx

GOLLIS UNIVERSITY

“Empowers its Students as Professional Leaders Committed to Make a Positive Difference”

CERTIFICATE

This is to certify that the project report entitled QoS ANAYYSIS IN WIMAX being submitted

by Mr. /Mrs.

Khaddar Ahmed Eggeh

Abu-Bakr Mohamed Handleh

A/Aziz Nour Ahmed

Zuhur Mohamed Ahmed

Partial fulfillment for the award of the Degree of Bachelor of Engineering in

Telecommunication to the Gollis University is a record of bona fide work carried out by him

under my guidance and supervision. The results embodied in this project report have not been submitted to any other

University or Institute for the award of any Degree or Diploma.

ENG. MOHAMOUD M. ESSA ENG.: BEWNET GETACHEW

Dean of the Department Designation

Badda-Cas Area, Jijiga-yar District

Hargeisa, Somaliland

Phone: +252-7- 9720134 Mobile: 9119911 SOMTEL

Email: [email protected]

Website: www.gollisuniversity.com

QUALITY OF SERVICE (Qos) ANAYYSIS IN

WIMAX

Project report submitted in partial fulfillment of the requirement for the award

Of the Degree of Engineering

Authors:

Khaddar Ahmed Eggeh GU-TEL-F-10-1703

Abu-Bakr Mohamed Handleh GU-TEL-E-11-844

A/Aziz Nour Ahmed GU-TEL-F-10-1471

Zuhur Mohamed Ahmed GU-TEL-F-10-1471

`

Department of Telecommunication Engineering

Gollis University

Hargeisa

Somaliland

2013

I

ACKNOWLEDGMENTS

We would like to express our sincere gratitude to our adviser, Eng. Bownet for support us and

motivation throughout the Project work. There were multiple times when we questioned our

decision to undertake the project option`. Every time, he successfully talked us out of it and put

us back on track.

We would also like to thank Eng. Iven Jackson and dean of telecom Eng. Mahmud Mohammed

Essa, whom not only pushed us to work on our degree, but continued to give us words of wisdom

when we really needed them.

They also got us really interested in PERL.

Eng. Bownet we have saved countless hours with the PERL scripts that we have written

including the one which we used for analyzing enormous amount of data generated by ns-2 trace

files.

We owe a lot to Eng. Bownet for guiding us through the setup of the use cases for simulation and

helping us during the analysis of data. We learnt a lot from them in terms of understanding of

WiMAX and QoS. Running and setting up the ns-2 would not have been possible without

invaluable help from Eng Bownet also gave very timely tips during the writing.

We would also like to thank Eng. Bownet for being part our committee.

Our family supported us throughout the long process.

We could not have been able to finish it without the full and unconditional support we received.

II

ABSTRACT

Title: QoS Analysis in WiMAX

University: Gollis University

Project Advisor: Eng. Bewnet Getachew

Degree: Undergraduate

Year: 2013

In last few years there has been significant growth in the area of wireless communication.

Quality of Service (QoS) has become an important consideration for supporting variety of

applications that utilize the network resources. These applications include voice over IP,

multimedia services, like, video streaming, video conferencing etc. IEEE 802.16/WiMAX is

a new network which is designed with quality of service in mind. This project focuses on

analysis of quality of service as implemented by the WiMAX networks. First, it presents the

details of the quality of service architecture in WiMAX network. In the analysis, a WiMAX

module developed based on popular network simulator ns-2 is used. Various real life

scenarios like voice call, video streaming are setup in the simulation environment.

Parameters that indicate quality of service, such as, throughput, packet loss, average jitter and

average delay, are analyzed for different types of service flows as defined in WiMAX.

Results indicate that better quality of service is achieved by using service flows designed for

specific applications.

III

TABLE OF CONTENTS

Chapter 1

1.1 INTRODUCTION ………………………………………………………………...…….1

1.1.1 Importance of WiMAX………………………………………………………...2

1.1.2 Applications ofWiMAX………………………………………………………....3

1.2 Problem Statement …..........................................................................................................4

1.3 Objective of the project …………………………………………………………..………6

1.4 Documentation.....................................................................................................................7

1.5 Limitations………………………………………………….……………………………..8

Chapter 2

2.1 LITERATURE REVIEW………………………………………………………….…..9

2.1.1 Types of WiMAX………………………………………………………………………....9

2.2 Mobile WiMAX……………………………………………………………………………..9

2.3 Parts of WiMAX System……………………………………………………………….....10

2.3.1 WiMAX Base Station……………………………………………………………...10

2.3.2 WiMAX Receiver (Subscriber Unit)………...……………………………….….10

2.4 WiMAX base station architecture………………………………………………………....10

2.4 .1 OFDM………………………………………………………….......... 11

2.5 Physical Layer Description……………………………………………………...…………12

2.5.1 OFDMA Basics …………………………………………………………………..13

2.5.2 TDD Frame Structure ……………………………………………………….....15

2.6 MAC Layer Description ………………………………………………………………...…15

2.7 QoS Support ……………………………………………………………………….…….....16

2.8 Mobility Management………………………………………………………………….......17

2.9 Security……………………………………………………………………………………...19

2.10.1Deployment and Frequency Reuse …………………………………………………......19

IV

2.11 WiMAX Qos Comparison………………………………………………………………...21

2.11.1WiMAX Comparison with Wi-Fi………………………………………………….....21

2.11.2 Frequency Band Difference………………………………………………………....21

2.11.3 Working Comparison……………………………………………………………...…22

2.11.4 Coverage Area and Mobility……………………………………………………...….23

2.11.5 Reliability and Security………………………………………………………………24

2.11.6 Data rates and latency difference…………………………………………………….25

Chapter 3

3.1METHODOLOGY……………………………………………………………………...26

3.1.2 Analysis of (QoS) in WiMAX Networks ………………………………………………..26

3.1.1 Quality of Service………………………………………………………………….….26

3.2 QoS Mechanism…………………………………………………………….……….……...27

3.3Contribution………………....................................................................................................29

3.4 WiMAX Network ……………………………………………………………………….….30

3.5 Advantages & Limitations of Qos Analysis of WiMax ……………………………….….30

3.5.1 Advantages of WiMAX……………………………………………………………….…..30

3.5.2 Limitations of WiMAX…………………………………………………………..…….…31

3.6 Risks for Embedding WiMAX in Consumer Electronics………………………………..32

3.7 Obstacles in WiMAX Progress in India…………………………………………………...32

3.8 Government Initiatives for the Progress of WiMAX………………………………….….33

Chapter 5

4.1 Data analysis and results …………………………………………………….….........34

4.1.1 Introduction ……………………………………………………………………..........34

4.2 Scenario 1 ………………………………………………………………………………...35

4.2.1 Objective…………………………………………………………………………..........35

4.2.2 Background…………………………………………………………………….........….35

4.2.3 Method……………………………………………………………………………….....35

V

4.2.4 Result …………………………………………………………………………..………36

4.3 Scenario 2 …………………………………………………………….……....37

4.3.1 Objective……………………………………………………………………………......37

4.3.2 Background………………………………………………………………………..........37

4.3.3 Method ………………………………………………………………………………....39

4.3.4 Results ……………………………………………………………………….…………40

4.4 Scenario 3 …………………………………………………………………………….….43

4.4.1 Objective………………………………………………………………………………..43

4.4.2 Background……………………………………………………………………………..43

4.4.3 Method ………………………………………………………………………………....43

4.4.4 Results …………………………………………………………………………….........44

4.4.5 Discussion and Conclusions …………………………………………………….……..46

Discussions and conclusions........................................................................................................47

List of acronyms ………………………………………………………………………………..49

Bibliography ……………………………………………………….…………………………...52

LIST OF TABLES

TABLES

Table 2.7 Qos category…......................................................................................................17

Table 2.11.1 Frequency Band Difference……………………………………………………..21

Table 2.11.4 Coverage Area and Mobility………………………………………………….....23

Table 2.11.5 Reliability and Security………………………………………………………....24

Table 2.11.6 Data rates and latency difference……………………………………………….25

Table 3.2 WiMax /802.16 Qos Model…………………………………………….…...….29

Table 4.3.3 parameters of light….. …………………………………………………….…...40

Table4.3.4: Comparison between light and dense scanning results ……………………….....41

VI

LIST OF FIGURES

FIGURES

FIGURE 2.2 WiMAX Network Descriptions…......................................................................9

FIGURE 2.4 Base station Architecture………………….………………….………………10

FIGURE 2.4.1 Typical Example Multi-path……….………………………………………11

FIGURE 2.5 Physical Layer Functions ...………………………………………………….13

FIGURE 2.5.1 Basic Architecture of an OFDM System………………………………….….14

FIGURE2.5.1 Insertion of cyclic prefixes (CP) ……………………………………….….....14

FIGURE 2.10.1 Frequency reuses patterns………………………………………...…….…….20

FIGURE 2.11.3 Wi-Fi Networks ………………………………………………………...……22

FIGURE 2.11.3 WiMAX Working ……………………………………………………….…...23

FIGURE 4.2.3: WiMAX mobility scenario…………………………………………….…..…35

FIGURE 4.2.4: Scanning and handover to BSs results………………………………………36

FIGURE 4.2.4: Data dropped and throughput………………………………………………...37

FIGURE 4.3.2: Mobile Station request…………………………………………………….….38

FIGURE 4.3.2: Activity between mobile and base station………………………………...….39

FIGURE4.3.3: Scenario 2 network topology………………………………………………....40

FIGURE4.3.4: Signal to Noise Ratio ………………………………………………..……….41

FIGURE 4.3.4: Traffic received – a comparison of the throughput………………….…….…42

FIGURE4.3.4: Time averaged WiMAX delay………………………………………….……42

FIGURE 4.3.4: Time averaged WiMAX packet jitter……………………………………..….43

FIGURE4.4.3: Ranging connectivity loss……………………………………………….…...44

FIGURE 4.4.4: Receive power and transmission power……………………………………...45

FIGURE 4.4.4: Traffic switch between BS_1 and BS_2……………………………………...45

Chapter1 introduction

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CHAPTER ONE

1.1 Introduction

WiMAX is defined as Worldwide Interoperability for Microwave Access by the WiMAX

Forum, formed in June 2001 to promote conformance and interoperability of the IEEE 802.16

standard, officially known as Wireless MAN

WiMAX is a standards-based technology enabling the delivery of last mile Wireless broadband

access as an alternative to cable and DSL (Digital Subscriber Line).

WiMAX will provide fixed, nomadic, portable and mobile wireless broadband Connectivity

without the need for direct line-of-sight with a base station.

It can be implemented in the Frequency range -:2 GHz – 66 GHz.

It is a more innovative and commercially viable adaptation of a technology already used to

deliver broadband wireless services in proprietary installations around the globe. As, wireless

broadband access systems are already deployed in more than 125 Countries.

The IEEE 802.16 group was formed in 1998 to develop an air-interface standard for wireless

broadband. The group's initial focus was the development of a LOS-based point-to-multipoint

wireless broadband system for operation in the 10GHz–66GHz millimeter wave band. The

resulting standard—the original 802.16 standard, completed in December 2001—was based on a

single-carrier physical (PHY) layer with a burst time division multiplexed (TDM) MAC layer.

Many of the concepts related to the MAC layer were adapted for wireless from the popular cable

modem DOCSIS (data over cable service interface specification) standard.

The basic characteristics of the various IEEE 802.16 standards are summarized in table. Note

that these standards offer a variety of fundamentally different design options. For example, there

are multiple physical-layer choices: a single-carrier-based physical layer called Wireless

MANSCa, an OFDM-based physical layer called Wireless MAN-OFDM, and an OFDMA-

based physical layer called Wireless-OFDMA. Similarly, there are multiple choices for MAC

Architecture, duplexing, frequency band of operation, etc. these standards were developed to suit

a variety of applications and deployment scenarios, and hence offer a plethora of design choices

for system developers. In fact, one could say that IEEE 802.16 is a collection of standards, not

one single interoperable standard.


2

The IEEE 802.16 group subsequently produced 802.16a, an amendment to the standard, to

include NLOS applications in the 2GHz–11GHz band, using an orthogonal frequency division

multiplexing (OFDM)-based physical layer. Additions to the MAC layer, such as support for

orthogonal frequency division multiple access (OFDMA), were also included. Further revisions

resulted in a new standard in 2004, called IEEE 802.16-2004, which replaced all prior versions

and formed the basis for the first WiMAX solution. These early WiMAX solutions based on

IEEE 802.16-2004 targeted fixed applications, and we will refer to these as fixed WiMAX . In

December 2005, the IEEE group completed and approved IFEEE 802.16e-2005, an amendment

to the IEEE 802.16-2004 standard that added mobility support. The IEEE 802.16e-2005 forms

The basic characteristics of the various IEEE 802.16 standards are summarized in table. Note

that these standards offer a variety of fundamentally different design options. For example, there

are multiple physical-layer choices: a single-carrier-based physical layer called Wireless

MANSCa, an OFDM-based physical layer called Wireless MAN-OFDM, and an OFDMA-

based physical layer called Wireless-OFDMA. Similarly, there are multiple choices for MAC

architecture, duplexing, frequency band of operation, etc. These standards were developed to

Suita variety of applications and deployment scenarios, and hence offer a plethora of design

choices for system developers. In fact, one could say that IEEE 802.16 is a collection of

standards, not one single interoperable standard.

1.1.1 Importance of WiMAX

WiMAX has been immensely helpful in critical situations even though this is an emerging and is

currently in preliminary stage. One such example is as follows:-

WiMAX access was used to assist with communications in Aceh, Indonesia, after the tsunami in

December 2004. All communication infrastructures in the area were destroyed making the

survivors unable to communicate with people outside the disaster area and vice versa. WiMAX

provided broadband access that helped regenerate communication to and from Aceh so that the

condition post-tsunami could be retrieved.


3

1.1.2 Applications of WiMAX

The WiMAX has huge range of applications ranging from telecom applications to wireless

broadband access systems.

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

Residential and SOHO High Speed Internet Access

WiMAX provides an alternative to existing access methods, where it is not feasible to use

DSL or Cable Internet.

Typical application will be in remote areas where it is not economically feasible to have a

DSL or Cable Internet.

Expected to be more reliable due to wireless nature of between the customer premises

and the base station.

Particularly useful in developing countries where the reliability and quality of land-line

communications infrastructure is often poor.

Small and Medium Business

WiMAX WBA is well suited to provide the reliability and speed for meeting the

requirements of small and medium size businesses in low density environments.

A diverse source of Internet connectivity as part of a business continuity plan.

Wi-Fi Hot Spot Backhaul

A WiMAX backhaul provides full wireless solution to these wireless networks.

Connecting Wi-Fi hotspots with each other and to other parts of the Internet.

Areas of low population density and flat terrain

Particularly suited to WiMAX and its range.

Interfacing with portable MP3 audio players and digital cameras

MP3 audio players and digital cameras rely on PC household’s to synchronize or transfer

content.


4

Mobile WiMAX connects these multimedia devices to the Internet, enabling new revenue

sources for operators and content owner’s while providing convenience and valuable new

services for consumers.

Promoting Media Libraries and lessening Storage Requirements

Consumer electronics devices that currently store music and video content can lessen

their storage requirements by streaming media tothe subscriber from home media

libraries or e -commerce portals. New content can be leased to consumers instead of

purchased. This leasing model of micro payments creates new revenue sources for the

network operator as well as the content owner

1.2 Problem Statement

This thesis focuses on the analysis QoS in the WiMAX. The details of the implementation of

QoS in the WiMAX network architecture will be presented. It includes the definition of various

service flows defined by the IEEE 802.16 standard.

The details of the network’s MAC layer QoS implementation are presented. To analyze the QoS

parameters simulation based on the popular network simulator ns-2 is used. Various parameters

that determine QoS of real life usage scenarios and traffic flows of applications is analyzed. The

goal is to compare different types of service flows with respect to the QoS parameters, such as,

throughput, average jitter, average delay and packet loss.

Wimax technology was designed to compete with remote locations that presently employs

satellite for internet connectivity. Wimax technology can operate on both licensed and non-

licensed frequencies. Wimax Technology is powerful mobile technology but is facing some

problems discussed below.

Lack of Quality

The Wimax network has lack of quality service because there are hundreds of people trying to

get access at the same tower so due to heavy traffic it is very hard to maintain high quality.


5

Wimax range

The other problem of Wimax network is range. As Wimax offer 70Mbps in range with moving

station but in practice it is quite different because it is possible only in specify or ideal

circumstances. If a user staying away from the specified environment then speed can drop

considerably.

Wimax Bandwidth

Like other network Bandwidth is collective amongst clients in a specified zone. But if there are

a lot of users in one area the speed decreases which may be 2 to 10 Mbps of shared bandwidth.

Expensive network

The most disadvantage of Wimax is its installation and operational cost. Due to heavy structure,

tower, antennas etc makes the Wimax network collectively high cost network.

Bad Weather

The quality of services decreases in rainy season because the weather condition could interrupt

the signal which may cause of bad signal and broadcasting may be stop or interrupted

Wireless equipments

If you are trying to use much wireless equipment at a time within Wimax network then these

equipments may cause of interference and could interference your broadcasting data or face

some compromised speed.

Power consuming

Wimax network is very heavy in structure therefore need much electrical support for running the

overall network.

Data Rate

The data rate of Wimax as compared to other network such as fiber optics, satellite, cables etc

are very slow.


6

Assumptions:

One cell

Channel conditions for all SS are similar so that all SS use the same modulation scheme

and coding rate.

Fixed sub-frame division

All connections are MPEG type of video traffic.

Ignore overheads from higher layers.

Ignore pilot and null OFDM sub-carriers.

Problem: model and simulate the network traffic using rtPS scheduling.

1.3 Objective of the project

Objectives of our project is mentioned the advantages of wimax and its quality of services.

Include wimax coverage, wimax high speed, multi-functional with in wimax and rich features of

wimax and also is mentioned the advantages of wimax and its quality of services.

As packets travel within a wireless network such as WiMAX, they experience the following

problems.

• Delay: Unpredictably longer time for packets to reach the destination due to unavailability of

network resources.

• Jitter - Packets from source will reach the destination with different delays. This variation in

delay is known as jitter and can seriously affect the quality of streaming audio and/or video.

• Out-of-order delivery: When a collection of related packets are routed through the Internet,

different packets may take different routes, each resulting in a different delay. The result is that

the packets arrive in a different order to the one with which they were sent. This problem

necessitates special additional protocols responsible for rearranging out-of-order packets once

they reach their destination.

• Packet loss or Error: Sometimes packets are misdirected, corrupted, or completely lost during

transit. If the packet was dropped, the receiver has to ask the sender to resend it. In case of bit

error detected in a packet, the receiver has to detect the error and, just as if the packet was

dropped, ask the sender to repeat it.


7

1.4 Documentation

Our project contains five chapters which are introduction, literature view, methodology, data

analysis and result and the last one is discussion and conclusion.

Introduction is described the over view of wimax such as definition and history of wimax also

importance of wimax as well as application of wimax and problem statement and objective of

our project

Literature view is discussed two types of wimax and our case study is mobile wimax

Parts of mobile wimax as well as physical and data link layer ofdm qos support and comparison

Of wimax and wife

Methodology is the third chapter of our project this chapter contains two thing which are

Analysis of qos of wimax and advantage and limitations of wimax

Data analysis and results is four chapter is to highlight mobility effects caused by a MS leaving

the vicinity of its initial BS and visiting seven other BSs before returning to the initial BS and

focuses on the scanning procedure that a WiMAX mobile station does when looking for more

suitable base stations in its vicinity and the last chapter is discussion and conclusion of our

project

.

1.5 Limitations

Limitation of qos of wimax include Tradeoff between Bandwidth and long reach, Lower Gain

antennas in Mobile WiMAX Products, Bandwidth Sharing, Shortage of Spectrum,

Low Cost End-To-End System and Government Initiatives for the Progress of WiMAX

Chapter2 Literature review

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CHAPTER TWO

2.1 Literature review

2.1.1 Types of WiMAX

There are two types of WiMAX system:-

Fixed WiMAX

Mobile WiMAX

In this project we will focus in mobile wimax

2.2 Mobile WiMAX

Mobile WiMAX refers to the system built using 802.16e-2005 as the air interface

technology. "Mobile WiMAX" implementations are therefore frequently used to

deliver pure fixed services.

WiMAX uses a Lower Frequency Range – 2 GHz to 11 GHz (Similar to Wi-Fi).

Since, Lower-wavelength transmissions are not as easily disrupted by physical

obstructions --they are better able to diffract, or bend, around obstacles. Hence,

lower frequency ranges are suitable for mobile communication and mobile

wireless internet service.

Mobile WiMAX is suitable for Mobile communication and mobile wireless broadband service in

cell phones, smart phones and laptops. It allows people to communicate while walking or riding

in cars and provides a mobile voice over IP (VoIP) and higher-speed data alternative to the

cellular networks (GSM, TDMA, CDMA).

WiMAX Network Description

FIG 2.2 WiMAX Network Descriptions


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2.3 Parts of WiMAX System

Typically, a WiMAX system consists of two parts:

1. WiMAX Base Station

2. WiMAX Receiver (subscriber Unit)

2.3.1 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 10 km or 6 miles). Any wireless node

within the coverage area would be able to access the Internet.

• 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.

2.3.2 WiMAX Receiver (Subscriber Unit)

• Is the Digital Base band Receiver that processes the I /Q Data

• The receiver and antenna could be a stand-alone box or a PCMCIA (Personal Computer

Memory Card International Association) card that sits in your laptop or computer. Access to

WiMAX base station is similar to accessing a Wireless Access Point in a Wi-Fi network, but the

coverage is more.

2.4: WiMAX Base Station Architecture

Fig.2.4 Base station Architecture


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2.4 .1 OFDM

The need for reliable broadband services in a non-line-of-sight (NLOS) wireless environment,

typically riddled by severe multi-path, and interference from other wireless service providers, has

driven the wireless industry to the widespread adoption of Orthogonal Frequency Division

Multiplexing (OFDM) in standards and products.[8]

Figure 2.4.1 Typical Example Multi-path

Multi-path Problem

For robustness, OFDM partitions the data stream into multiple narrowband transmissions in the

frequency domain using subcarriers that are orthogonal to one another.

Mobile wimax

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 63 Mbps 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 Diffusers 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


12

Scalability: Despite an increasingly globalized 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 channelizations 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 multi-faceted

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 50

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

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

2.5 Physical Layer Description

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. Sub channeling in uplink

and smart antennas at the base station has to overcome these constraints. The WiMAX system

relies on a new radio physical (PHY) layer and appropriate MAC (Media Access Controller)

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, and best effort). The OFDMA PHY layer is well adapted to the

NLOS propagation environment in the 2 - 11 GHz frequency range. It is inherently 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.


13

Figure 2.5 Physical Layer Functions

2.5.1 OFDMA Basics

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

subdivides the bandwidth into multiple frequency sub-carriers as shown in Figure 9.3.1. 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 in Figure 9.3.2. 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 ―roll-off 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.


14

Figure 2.5.1 Basic Architecture of an OFDM System

OFDM exploits the frequency diversity of the multipath channel by coding and interleaving the

information across the sub-carriers prior to transmissions. OFDM modulation can be realized

with efficient Inverse Fast Fourier Transform (IFFT), which enables a large number of sub-

carriers (up to 2048) with low complexity. In an OFDM system, resources are available in the

time domain by means of OFDM symbols and in the frequency domain by means of sub-carriers.

The time and frequency resources can be organized into sub-channels for allocation to individual

users. Orthogonal Frequency Division Multiple Access (OFDMA) is a multiple-

access/multiplexing scheme that provides multiplexing operation of data streams from multiple

users onto the downlink sub-channels and uplink multiple accesses by means of uplink sub-

channels.

Figure 2.5.1 insertion of cyclic prefix (CP)


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2.5.2 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.

2.6 MAC Layer Description

The 802.16 standard was developed from the outset for the delivery of broadband services

including voice, data, and video. The MAC layer is based on the time-proven DOCSIS standard

and can support bursty data traffic with high peak rate demand while simultaneously supporting

streaming video and latency-sensitive voice traffic over the same channel. The resource allocated

to one terminal by the MAC scheduler can vary from a single time slot to the entire frame, thus

providing a very large dynamic range of throughput to a specific user terminal at any given time.

Furthermore, since the resource allocation information is conveyed in the MAP messages at the

beginning of each frame, the scheduler can effectively change the resource allocation on a frame-

by-frame basis to adapt to the bursty nature of the traffic.

Every wireless network operates fundamentally in a shared medium and as such that requires a

mechanism for controlling access by subscriber units to the medium. The 802.16a standard

Uses a slotted TDMA protocol scheduled by the BTS to allocate capacity to subscribers in a

point-to-multipoint network topology While this on the surface sounds like a one line, technical

throwaway statement, it has a huge impact on how the system operates and what services it can

deploy. By starting with a TDMA approach with intelligent scheduling, WiMAX systems will be

able to deliver not only high speed data with SLAs, but latency sensitive services such as voice

and video or database access are also supported. The standard delivers QoS beyond mere

prioritization, a technique that is very limited in effectiveness as traffic load and the number of

subscriber‘s increases. The MAC layer in WiMAX certified systems has also been designed to


16

address the harsh physical layer environment where interference, fast fading and other

phenomena are prevalent in outdoor operation. We can see major 802.16a MAC features

2.7 QoS Support

With fast air link, symmetric downlink/uplink capacity, fine resource granularity and a flexible

resource allocation mechanism, Mobile WiMAX can meet QoS requirements for a wide range of

data services and applications.

In the Mobile WiMAX MAC layer, QoS is provided via service flows as illustrated in Figure 9.6

This is a unidirectional flow of packets that is provided with a particular set of QoS parameters.

Before providing a certain type of data service, the base station and user-terminal first establish a

unidirectional logical link between the peer MACs called a connection. The outbound MAC then

associates packets traversing the MAC interface into a service flow to be delivered over the

connection. The QoS parameters associated with the service flow define the transmission

ordering and scheduling on the air interface. The connection-oriented QoS therefore, can provide

accurate control over the air interface. Since the air interface is usually the bottleneck, the

connection-oriented QoS can effectively enable the end-to-end QoS control. The service flow

parameters can be dynamically managed through MAC messages to accommodate the dynamic

service demand. The service flow based QoS mechanism applies to both DL and UL to provide

improved QoS in both directions

Support for quality of service (QoS) is essential for broadband wireless systems with channels

designed to simultaneously carry a combination of voice, video, and data services. QoS

algorithms are required to ensure that the shared use of the channel does not result in service

degradation or failure. Examples include jerky or abrupt video streams, latency levels in a voice

call that interfere with natural conversation or the download of an Internet page that is

unacceptably delayed or freezes. Despite the fact that subscribers are sharing the broadband link

with others, they expect an acceptable level of performance from the service provider under all

conditions.

The mobile WiMAX standard provides a suite of tools to support QoS for multiple applications.

The WiMAX base station allocates all uplink and downlink airtime resources using a traffic


17

scheduling procedure that reflects traffic demand and the subscription parameters of individual

subscribers Comprehensive algorithms are then employed to ensure that the application-specific

QoS parameters are met. The following table provides a summary of the QoS categories,

applications and QoS parameters to be controlled as delineated in the 802.16e-2005 standard.

Table 2.7 Qos category

2.8 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.


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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) users remain connected within an entire metropolitan area. For example, a notebook could

connect via Ethernet or 802.11 when docked, and stay connected with 802.16 when roaming the

city or suburbs.

There are three handoff methods supported within the 802.16e standard – Hard Handoff (HHO),

Fast Base Station Switching (FBSS) and Macro Diversity Handover (MDHO). Of these, the

HHO is mandatory while FBSS and MDHO are two optional modes. The WiMAX Forum has

developed several techniques for optimizing hard handoff within the framework of the 802.16e

standard. These improvements have been developed with the goal of keeping Layer 2 handoff

delays to less than 50 milliseconds.


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2.9 Security

Mobile WiMAX supports best in class security features by adopting the best technologies

available today. Support exists for mutual device/user authentication, flexible key management

protocol, strong traffic encryption, control and management plane message protection and

security protocol optimizations for fast handovers. The usage aspects of the security features are:

Key Management Protocol. Privacy and Key Management Protocol Version 2 (PKMv2)

is the basis of Mobile WiMAX security as defined in 802.16e. This protocol manages the

MAC security using Traffic Encryption Control, Handover Key Exchange and

Multicast/Broadcast security messages all are based on this protocol.

Device/User Authentication. Mobile WiMAX supports Device and User Authentication

using IETF EAP (Internet Engineering Task Force Extensible Authentication Protocol)

by providing support for credentials that are SIM-based, USIM-based or Digital

Certificate or Username/Password-based.

Traffic Encryption. Cipher used techniques for protecting all the user data over the

Mobile WiMAX MAC interface. The keys used for driving the cipher are generated from

the EAP authentication. A Traffic Encryption State machine that has a periodic key

(TEK) refresh mechanism enables sustained transition of keys to further improve

protection.

Fast Handover Support: A 3-way Handshake scheme is supported by Mobile WiMAX

to optimize the re-authentication mechanisms for supporting fast handovers. This

mechanism is also useful to prevent any man-in-the-middle-attacks.

2.10 Deployment and Frequency Reuse

To maximize coverage and frequency reuse while minimizing interference, terrestrial wireless

systems cover the service area with multiple cells, which are further subdivided into multiple

sectors. Since some subscribers may be located at the boundaries between cells or sectors and

potentially receive signals from multiple sources – thus creating interference – each sector is

typically assigned a different frequency channel. Then, in accordance with an overall radio plan

for the area, each channel is reused with a spatial separation in order to maximize the use of the

limited spectrum while minimizing self-interference from the same channel being reused

elsewhere in the network. This is commonly referred to as co-channel interference (CCI).


20

The ‗reuse factor‘, a measure of how aggressively a given frequency is reused, is expressed as a

fraction of the sectors or cells operating with the same frequency channel. Typical reuse factors

for traditional cellular systems are 3 or 7 – resulting in the need for 3 or 7 different frequency

channels to implement a specific multi-cellular radio plan.

Figure 2.10.1: Frequency reuses patterns: [8]

frequencies (Digital systems)

frequencies (Analog FDMA)

OFDMA and CDMA

An alternative approach, used in both CDMA and OFDMA, is to use all available frequency

channels within each sector and to use robust modulation schemes, such as OFDMA or CDMA,

to deal with the high levels of interference from adjacent sectors or cells. This is referred to as

having a reuse factor of 1 sometimes called ‗reuse-1‘ or ‗universal frequency reuse‘ – and is very

popular with today‘s carriers since it eliminates the need for detailed network radio planning. To

support universal frequency reuse, these modulation schemes handle interference through the use

of strong error correction codes such as convolution turbo codes (CTC) and by using a subset of

the available bandwidth through the use of access codes, in the case of CDMA, and subcarriers,

in the case of OFDMA. The mobile WiMAX standard also provides the ability to orthogonally

split resources within a cell while randomizing subcarrier allocations between cells. The

orthogonal split within the cell assures that there is little or no interference between adjacent

sectors, while the randomization of subcarrier allocations between cells assures that there is little

overlap between subcarriers used for specific subscribers in adjacent cells. This mitigates the

potential for cell-to-cell interference and enables the air link to operate at higher modulation

efficiency, resulting in higher data throughput.


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2.11 WiMAX Qos Comparison

2.11.1 WiMAX Comparison with Wi-Fi

The technology used in both WiMAX and Wi-Fi is same but the biggest difference comes in the

coverage area. They are based upon IEEE standards 802 and both have a connection to wireless

connectivity and the Internet but both are used at different applications. Wi-Fi is widely used for

indoor purposes and for short range .Wi-Fi actually has been designed for LAN whereas

WiMAX designed for MAN. Actually the wireless connections were available only on hot spots

like airports, stations etc but now a days there is increase demand of wireless mobile connections

at every place even they are traveling in bus along with the same data rates as they find in their

fixed desktop computer, to achieve such kind of demands WiMAX was introduced .WiMAX has

same sort of setup like cellular network with smart antenna technology and efficient use of

spectrum WiMAX has many advantages as compared to Wi-Fi like WiMAX is robust, more

security options, good quality of service.

2.11.2 Frequency Band Difference

The original WiMAX standard, IEEE 802.16, specifies WiMAX in the 10 to 66 GHz range.

802.16a added support for the 2 to 11 GHz range, of which most parts are already unlicensed

internationally and only very few still require domestic licenses. There is a frequency band

differences between two of them. WiMAX uses licensed spectrum whereas Wi-Fi uses

unlicensed spectrum WiMAX can operate in licensed spectrum as well as unlicensed spectrum

.Following spectrum band are particularly used.

Licensed 2.5 GH Spectrum: Licensed spectrum of range 2.5 to 2.7 GH is used in USA

Licensed 3.5 GH Spectrum: 3.4 to 3.7 range of spectrum is used throughout rest of the world

especially in Europe and originally used for wireless local loop.

Unlicensed 3.5 GH: For fixed location wireless services an unlicensed spectrum of range

3.65 to 3.7 are used in USA.

Unlicensed 5GH Band: Another unlicensed spectrum ranging 5.150 to 5.350 and 5.470 to 5.825

GH is also used in USA.

Table 2.11.1 Frequency Band Difference


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2.11.3 Working Comparison

Wi-Fi uses radio waves, just like cell phones, televisions and communication across a wireless

network is mostly similar to full duplex radio communication. A computer's wireless adapter

converts data into a radio signal and transmits it using an antenna. A wireless router receives the

signal and decodes it. It sends the information to the Internet using a physical, wired Ethernet

connection. The process also works vice versa with the router receiving information from the

Internet, converting it into a radio signal and sending it to the computer's wireless adapter.

Figure 2.11.3 Wi-Fi Networks

WiMAX works in the same way but at higher speeds over greater distances and numbers of users

also increased. Mainly WiMAX consists of two parts:

A WiMAX tower, similar as used in a cell-phone tower - A single WiMAX tower can

provide coverage to a very large area

A WiMAX receiver - The receiver and antenna could be a small box or PCMCIA card, or

they could be built into a laptop like Wi-Fi.

A WiMAX tower station can connect directly to the Internet using a high-bandwidth, wired

connection and it can also connect to another WiMAX tower using a LOS microwave link which

is also called backhaul.


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Figure 2.11.3 WiMAX Working

2.11.4 Coverage Area and Mobility

Table 2.11.4 Coverage Area and Mobility

Wi-Fi has a very limited range up to 30 m as compared to WiMAX which is up to 50 km radius

from base station however practical considerations limit it to about 10 km or 6 miles any wireless

node within the coverage area would be able to access the internet. The biggest challenge is the

mobility and to provide low latency and low packet loss handovers of data streams while user is

in moving situation from one access point to another access point is clearly a big task.

The 802.16 MAC includes many features suitable for a broad range of applications at different

mobility rates such as


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• Suppression of header, packing and fragmentation are very efficient method which are

commonly used in spectrum

• Support for Broadcasting and multi casting

• Handovers with high speed and management of mobility with primitives

• There are three management levels for power which are: sleep, idle and normal operations.

2.11.5 Reliability and Security

Table 2.11.5 Reliability and Security

WEP

In 802.11 WEP (wired equivalent privacy) provides a level of authentication .WEP was designed

to prevent casual eavesdropping, the objective was to provide same type of security level as in

wired LAN. It can be implemented in hardware as well as in software allowing it to be very

efficient.

SSID

To increase privacy and security another method is use of SSID (service set identifier).use of

SSID is intended to direct stations to the correct AP in cases where multiple Access points exist.

It can be used to keep casual users from gaining access to your network

MAC address

This technique involves the use of physical MAC address of client this is useful but it can also

easily be breached.

WiMAX Security

VPN can be very effective method for providing security. A basic principle in WiMAX networks

is that each subscriber station must have a X.509 certificate that will uniquely identify the

subscriber. The use of X.509 certificates makes it very difficult for any intruder to spoof the

identity of authentic users, providing sufficient protection against theft of service. A basic flaw in

the authentication method by using privacy and key management (PKM) protocol in WiMAX is

the lack of base station (BS) or service provider authentication. This makes WiMAX networks

disposed to man-in-the-middle scenario, exposing subscribers to various confidential information

and availability attacks. The 802.16e alteration added support for the Extensible Authentication


25

Protocol (EAP) to WiMAX networks. Support for EAP protocols is currently optional for service

providers. There are plans to include AES (advanced encryption standard).

Modulation Techniques Comparison

802.11b radio link uses a direct sequence spread spectrum technique called

complementary code keying (CCK).it is modulated with QPSK (quadrature phase shift

keying).

802.11 a and g radio link use 64 channel orthogonal frequency division

multiplexing(OFDM).the transmitter encodes the bit stream on the 64 sub carriers using

binary phase shift keying(BPSK),quadrature phase shift keying(QPSK). WIMAX

standards define three options for radio link.

SC-A: Single Carrier Channel

OFDM: 256 sub carrier orthogonal frequency division multiplexing

OFDM-A: 2048 sub carrier orthogonal frequency division multiplexing

2.11.6 Data rates and latency difference

Table 2.11.6 Data rates and latency difference

One of the main difference between WiMAX and Wi-Fi is the difference between the data rates

WiMAX has more data rates maximum up to 100 mbps as compared to Wi-Fi which is 54 mpbs.

The WiMAX configurations have improved many deficiencies of the Wi-Fi standard by

providing increased bandwidth and data rates

Chapter3 METHODOLOGY

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CHAPTER THREE

3.1 METHODOLOGY

In this chapter we are going to perform analysis of (QoS) in WiMAX networks and advantage

and limitations of mobile wimax.

Objective of This chapter is presented details of the WiMAX network. Next the focus is on the

implementation of QoS mechanism in MAC layer.

Then various types of service flows as defined by WiMAX are described in detail .Finally,

Advantages & Limitations of Qos Analysis of WiMax.

3.1.1 Analysis of (QoS) in WiMAX Networks

3.1.2 Quality of Service

As packets travel within a wireless network such as WiMAX, they experience the following

problems.

Delay: Unpredictably longer time for packets to reach the destination due to

unavailability of network resources

Jitter - Packets from source will reach the destination with different delays. This

variation in delay is known as jitter and can seriously affect the quality of streaming

audio and/or video.

Out-of-order delivery: When a collection of related packets are routed through the

Internet, different packets may take different routes, each resulting in different delay.

The result is that the packets arrive in a different order to the one with which they were

sent. This problem necessitates special additional protocols responsible for rearranging

out-of-order packets once they reach their destination.

Packet loss or Error: Sometimes packets are misdirected, corrupted, or completely lost

during transit. If the packet was dropped, the receiver has to ask the sender to resend it.

In case of bit error detected in a packet, the receiver has to detect the error and, just as if

the packet was dropped, ask the sender to repeat it.

There is no formal definition of Quality of service. QoS, in the field of telephony, was defined in

1994 in the International Telecommunication Union (ITU) Recommendation E.800. This

definition is very broad, listing 6 primary components: Support, Operability, Accessibility,

Retain ability, Integrity and Security. In 1998, the

ITU published a document discussing QoS in the field of data networking. The term


27

Quality of Service refers to the probability of the telecommunication network meeting a given

traffic contract. In the field of packet-switched networks and computer networking it is used

informally to refer to the probability of a packet succeeding in passing between two points in the

network. Although the name suggests that it is a qualitative measure of how reliable and

consistent a network is, there are a number of

Jitter - Packets from source will reach the destination with different delays. This variation

in delay is known as jitter and can seriously affect the quality of streaming audio and/or

video.

Out-of-order delivery: When a collection of related packets are routed through the

Internet, different packets may take different routes, each resulting in a different delay.

The result is that the packets arrive in a different order to the one with which they were

sent. This problem necessitates special additional protocols responsible for rearranging

out-of-order packets once they reach their destination.

Packet loss or Error: Sometimes packets are misdirected, corrupted, or completely lost

during transit. If the packet was dropped, the receiver has to ask the sender to resend it. In

case of bit error detected in a packet, the receiver has to detect the error and, just as if the

packet was dropped, ask the sender to repeat it.

There is no formal definition of Quality of service. QoS, in the field of telephony, was defined in

1994 in the International Telecommunication Union (ITU) Recommendation E.800. This

definition is very broad, listing 6 primary components: Support, Operability, Accessibility,

Retain ability, Integrity and Security. In 1998, the

ITU published a document discussing QoS in the field of data networking. The term

Quality of Service refers to the probability of the telecommunication network meeting a given

traffic contract. In the field of packet-switched networks and computer networking it is used

informally to refer to the probability of a packet succeeding in passing between two points in the

network. Although the name suggests that it is a qualitative measure of how reliable and

consistent a network is, there are a number of

3.2 QoS Mechanism

Providing efficient QoS support is essential to various networks, as they need to deliver real-time

services like video, audio, and voice over IP. There are essentially two ways to provide QoS

guarantees. The first is to simply provide lots of resources, enough to meet the expected peak

demand with substantial safety margin.

This approach generously over provisions the network. All packets get a quality of service

sufficient to support applications sensitive to QoS. This approach is relatively simple, but some

people believe it to be expensive in practice. It cannot cope if the peak demand increases faster

than predicted. Deploying the extra resources takes time. For wireless networks, since the

capacity of a wireless channel varies randomly with time, over provisioning the network for QoS


28

support will end up resulting in waste of resources. Hence, this approach is not feasible for

commercial networks.

The second approach is requiring people to make reservations, and only accept the reservations if

the routers are able to serve them reliably. This is known as admission control.

To provide QoS support in IP layer (layer 3) there are two popular methods:

Integrated Services (IntServ) : Briefly described, IntServ is a model used for providing

traffic forwarding service levels in networks. It allows for micro flows to be created with

reserved resources (such as bandwidth) and other traffic handling characteristics

(maximum packet size, maximum burst size, etc.). Traffic is pushed into these micro

flows in the direction of the required destination. IntServ is implemented by four

components: the signaling protocol (e.g. Resource reservation Protocol RSVP), the

admission control, the classifier and the packet scheduler. Applications requiring

guaranteed service or controlled-load service must set up the paths and reserve resources

before transmitting their data. The admission control routines will decide whether a

request for resources can be granted. After classification of packets in a specific queue,

the packet scheduler will then schedule the packet to meet its QoS requirement 6

Differentiated Services (DiffServ): Briefly described, DiffServ is architecture for

providing different types or levels of service for network traffic. One key characteristic of

diffserv is that flows are aggregated in the network, so that core routers only need to

distinguish a comparably small number of aggregated flows, even if those flows contain

thousands or millions of individual flows. The IEEE 802.16 standard includes the QoS

mechanism in the MAC layer (layer 2) architecture. It defines service flows which can

map to DiffServ code points. This enables end-to-end IP based QoS. Among other things,

the MAC layer is responsible for scheduling of bandwidth for different users. The MAC

layer performs bandwidth allocation based on user requirements as well as their QoS

profiles. The standard is designed to support a wide range of applications. These

applications may require different levels of QoS. To accommodate these applications, the

802.16 standard has defined five service flow classes. They are


29

Table 3.2 wimax /802.16 Qos Model

These service flows can be created, changed, or deleted by the issuing Dynamic Service Addition

(DSA), Dynamic Service Change (DSC), and Dynamic Service Deletion (DSD) messages. Each

of these actions can be initiated by the

Subscriber Station (SS) or the Base Station (BS) and are carried out through a two or three-way-

handshake. For example, a new service flow initiated by the SS is built as follows. When SS

detects the emergence of a new service flow, it will calculate the available resources to determine

whether a DSA request will be sent or not. Upon reception of the DSA request, the BS verifies

whether this request can be supported, and sends a DSA response. Based on the DSA response,

the SS sends a DSA acknowledgement and enables the new service flow if the request is

approved. The standard provides some rules to classify Diff Server IP packets into different

priority queues based on IP QoS indication bits in IP header. So, in general, the QoS architecture

of IEEE 802.16 can support both IntServ and Diff Server.

3.3 Contribution

A WiMAX module written for ns-2 is used to simulate real life situations and analyze the effect

of various network conditions and load on QoS parameters. The parameters that will be

considered are throughput, average jitter, percentage packet loss and average delay. Use cases

simulated VOIP traffic and multimedia streaming traffic. The VOIP traffic is set up using five

different VOIP codecs which have different packet size and data rates. The effect of number of

nodes in the network requesting VOIP traffic is analyzed. The experiment is repeated for all the

five VOIP codecs. The VOIP traffic is set up using the three supported service flows that are


30

9supported namely, best effort (BE), real-time polling service (rtPS) and unsolicited grant

service (UGS). The effect of the service flow on the quality of service parameters such as

throughput, average jitter and packet loss is studied.

Next, the use case of streaming video is case is studied. The effect of number of nodes on the

multimedia traffic is analyzed for different service flows. Similar tothe case of VOIP traffic, the

analysis is done based on the four QoS parameters namely, throughput, average jitter, average

delay and packet loss. The results of the experiments are analyzed and conclusions are presented.

3.4 WiMAX Network

The WiMAX End-to-End Network Systems Architecture document defines the WiMAX

Network Reference Model (NRM). It is a logical representation of the network architecture. The

NRM identifies functional entities and reference points over which interoperability is achieved.

The architecture has been developed with the objective of providing unified support of

functionality needed in a range of network deployment models and usage scenarios.

Figure 1 shows basic components of a WiMAX network. The subscriber stations (SS) are

connected over the air interface to the base station (BS). The base station is part of the Access

Service Network (ASN) and connects to the Connectivity

Service Network (CSN) through the ASN Gateway. In generic telecommunication terminology,

ASN is equivalent to RAN (Radio Access Network) and CSN is equivalent to Core.

3.5 Advantages & Limitations of Qos Analysis of WiMax

3.5.1 Advantages of WiMAX

Spectral Efficiency

802.16-2004 (fixed) has a spectral efficiency of 3.7 bit/s/hertz, as compared to

similar technologies that often are less than 1 bit/s/hertz efficient such as Wi-Fi.

Nomadic Connectivity

A wireless alternative to cable and DSL for last mile broadband access.


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Enhancing Wireless Infrastructure

Can enhance wireless infrastructure of developing countries in an inexpensive,

decentralized, deployment-friendly and effective manner.

High-speed data and telecommunications services.

A diverse source of Internet connectivity as part of a business continuity plan.

Lower cost

The common platform drives down costs with volume opportunity. Fixed wireless

Customer Premise Equipment (CPE) will be able to use the same modem chipset

used in personal computers (PCs) and PDAs.

The base stations will be able to use the same chipsets developed for low-cost

WiMAX access points.

Finally increased volume will also justify the investment for higher-level integration

of radio frequency (RF) chipsets, further driving down costs.

Wider coverage

Provide excellent non line of sight (NLOS) coverage, advantages are coverage of

wider area, better predictability of coverage and lower cost as it means fewer base

stations and backhaul, simple RF planning, shorter towers and faster CPE install

times.

Higher capacity

A key advantage of WiMAX is to use OFDM (Orthogonal Frequency Division

Multiplexing) over single carrier modulation schemes with the ability to deliver

higher bandwidth efficiency and therefore higher data throughput, with more than

1Mbps downstream and even much higher data rates, even in NLOS with multipath

condition.

Enabling new applications that improve daily life.

First wireless WAN protocol built from the ground up for IP networking, the same

standards that the Internet is based on.

WiMAX does not rely on low data rate, high-latency, circuit-switched voice

technology.

Qualities of service (QoS) mechanisms are built into the WiMAX chipsets to support

and manage multiple service flows.


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3.5.2 Limitations of WiMAX

Tradeoff Between Bandwidth and Long reach

WiMAX has some similarities to DSL in this respect, where one can either have

high bandwidth or long reach, but not both simultaneously.

Lower Gain antennas in Mobile WiMAX Products

Mobile WiMAX devices typically have an antenna design which is of lower-gain by

nature due to their inherent omnidirectional (and portable) design.

This means that in a line-of-sight environment with a portable Mobile WiMAX CPE,

symmetrical speeds of 10 Mbit/s at 10 km could be delivered, but in urban

environments it is more likely that these devices will not have line-of-sight and

therefore users may only receive 10 Mbit/s over 2 km.

Higher-gain directional antennas can be used with a Mobile WiMAX network with

range and throughput benefits but the obvious loss of practical mobility.

Bandwidth Sharing

Like most wireless systems, available bandwidth is shared between users in a given

radio sector, so performance could deteriorate in the case of many active users on a

single sector.

Spectral Limitation

For use in high density areas, it is possible that the bandwidth may not be sufficient

to cater to the needs of a large clientele, driving the costs high.

3.6 Risks for Embedding WiMAX in Consumer Electronics

Current Mobile WiMAX chipsets do not meet acceptable levels of power

consumption and heat dissipation for integration into battery –powered handset

devices.

Large service networks do not yet exist for Mobile WiMAX. Champions of 3G data

protocols for broadband wireless network adoption point to existing circuit-switched

networks built over the last 10 years as the quickest path to a ubiquitous network.


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Spectrum allocations for WiMAX vary in each country. Initial consumer electronics

devices will be frequency or certification profile -specific (2.3 GHz, 2.5 GHz, or 3.5

GHz, for example).

3.7 Obstacles in WiMAX Progress in India

Shortage of Spectrum

For WiMAX to prosper in India, license holders will need at least 20MHz of

spectrum while they currently hold 12MHz or less. 20MHz is a minimum to support

wide scale deployments and hence a profitable business case.

Low Cost End-To-End System

In a country where monthly broadband ARPU is estimated at $8-10, and computer

penetration is still at around 4%, BWA / WiMAX adoption will depend on very low

cost end-to-end pricing for connectivity including the compute platform and CPE.

The Indian telecom sector operates in a volume-driven market. If WiMAX is to

succeed it will only be on the premise of huge volumes not, small deployments.

Non-Availability of Bandwidth

Pressure on available bandwidth is coming from operators who require allocations of

the 3G/UMTS spectrum. BWA/WiMAX technologies require specific frequency

bands to be opened up in the 3.5 GHz band (an internationally approved standard),

which is currently allocated to the Department of Space for INSAT downlink.

3.8 Government Initiatives for the Progress of WiMAX

Government appears to be serious about solving the problem by releasing some of

the spectrum from the departments of Space and Defense and the TRAI is currently

engaged in a critical public consultation.

The telecom ministry is initiating an ambitious project to release a total of about 45

MHz of spectrum from the Department of Defense to augment necessary spectrum

for 3G services.

Chapter4 Data analysis and results

34

CHAPTER FOUR

4.1 Data analysis and results

This simulation was taken on of the most important in Qos analysis of wimax books this chapter

Was clearly discussed how mobile was simulated when connecting in wimax

For a previous chapter we have done analysis of (QoS) in WiMAX networks and advantage and

limitations of mobile wimax

The case of study of this chapter data analysis and results as well as simulation

OPNET is capable of configuration of WiMAX in the network model, and also WiMAX

parameters needed for simulation. As an alternative and for future work, we can also do a

simulation and analysis on the WiMAX performance in wireless metropolitan area networks.

4.1 Introduction

WiMAX mobility was added to IEEE 802.16 WiMAX standards as an amendment named

“Mobile WiMAX” as 802.16e in` 2005. This set of standards specifically determines the rules

and regulations for end-user broadband access. The objective of this research is to give an

understanding of WiMAX mobility. Furthermore, this project illustrates some of the important

features of mobile WiMAX in practice, and specifically focuses on the following three scenarios:

Understanding Mobility

Hand-Over and Scanning

Ranging Connectivity Loss

Understanding Mobility gives a brief and basic introduction and understanding on mobile

WiMAX, in a situation where a mobile station deals with a set of geographically pre-assigned

base stations

Hand-Over and Scanning, shows the two steps that a mobile station and a base station have to go

through in order for the mobile station to switch over to one station from another currently

connected station, while on the move.

Ranging Connectivity Loss deals with the range of connectivity and the loss of connectivity as

the mobile station moves away from one base station along a certain trajectory and then comes to

the proximity of the other base station.

The base model for this project and the various scenarios was chosen from one of the WiMAX

samples and necessary changes were applied while the important default values and parameters

were kept unchanged.


35

4.2 Scenario 1

4.2.1 Objective

This scenario is to highlight mobility effects caused by a MS leaving the vicinity of its initial BS

and visiting seven other BSs before returning to the initial BS. While on the move, different

parameters of the scenario design, such as the SNR level, are checked, monitored and analyzed.

4.2.2 Background

When a mobile station is on the move along a trajectory, considering the fact that all the base

stations are within a certain distance from each other, brings the issue of the signal transmission

power of the MS and BS as the MS moves from one station and switches over to another one on

the trajectory. One important measurement parameter is the SNRratio that is to be monitored

along the way. As the MS is moving, there is a circle of acertain radius that defines a minimum

threshold of SNR outside of which the signal to noise ratio is too low.

4.2.3 Method

The server, the IP network, 7 base stations and a mobile station are chosen to build the scenario.

The server was chosen to support a variety of applications namely: Web Browser, Email, Telnet

and File Transfer. The base station is called the “Home Agent”.

The trajectory starts from the home agent and follows the path through all the base stations till

BS_7 and returns back to the home agent. The characteristics of the model are:

Mobile station node supports IPv4

Same data rate supported for UL and DL

Data rate of 64 kbps is supported

Connection based on Best Effort service

Outside of the circle (blue) the SNR ratio drops down to 27 dB

64 QAM modulation is supported

Figure-1 Below is an illustration of the method. The scenario was run for 10 minutes in the

simulation which took about 20 minutes to finish


36

Figure 4.2.3: WiMAX mobility scenario

4.2.4 Result

Figure 2 and figure 3 show the simulation results for this scenario.

The first graph in figure 2 indicates the initial ranging activity. As seen from the graph,

whenever MS connects to a BS, it performs an initial ranging activity to confirm the

threshold power is enough to stop scanning process.

-The second graph in figure 2 indicates mobility scanning that the MS conducts before

connecting to a BS.

The third and fourth graphs in figure 2 show the SNR at the physical layer of the model.

As seen from the graphs, the maximum SNR is attained when the MS is closest to the BS

and the minimum SNR is attained when MS is scanning for a BS.

The first graph of figure 3 shows the data dropped. As seen from the graph, the maximum

data is dropped when the MS is out of range and is in scanning process.

The second and third graphs of figure 3 show the delay and throughput. As seen from the

graph, throughput is the inverse graph of the data dropped graph. When the MS is in

scanning range, there is a dip in the throughput graph.


37

Figure 4.2.4: Scanning and handover to BSs results

Figure 4.2.4: Data dropped and throughput


38

4.3 Scenario 2

4.3.1 Objective

This scenario focuses on the scanning procedure that a WiMAX mobile station does when

looking for more suitable base stations in its vicinity. We modify three parameters and analyze

the effects. These parameters are scan duration, inter leaving interval, and number of iterations.

We differentiate between light scanning and dense scanning. We intend to show that light

scanning allows for more data throughput from server to client, while dense scanning has a lower

throughput but less handover delay.

4.3.2 Background

While a WiMAX mobile station is moving, it constantly scans for neighboring base stations and

transfers data between itself and the base station that it is currently connected with. The purpose

of these scans is to determine if it could acquire a connection with a more suitable base station.

This could be because of a better wireless signal SNR, a base station with lower traffic, etc.

When a mobile station first communicates with a base station, it is responding to an advertising

message that is sent out periodically by the base station information clients of various conditions

of the base station. This response requests bandwidth usage of the base station along with the

three key parameters we are modifying and measuring the impact of: scan duration, interleaving

interval, and number of iterations. The process of sending the request is shown in

Figure 4.3.2: Mobile Station request


39

The scan duration is a period of N frames during which the mobile station scans neighboring

base stations and acquires information about them. The interleaving intervals a period of P

frames during which the mobile station handles normal data transmission between itself and the

base station it is currently connected to. It repeats pairs of N scan frames and P interleaving

interval frames T times. At that point, it must reconnect to the current base station or a new base

station.

Figure 4.3.2: Activity between mobile and base station

In the figure 4.3.2, notice on the leftmost side Iteration 1. This contains a scanning period, and a

non-scanning interleaving interval. This is followed by T-1 more of these until the connection

are terminated by the base station and the mobile station must request a new connection.

In our simulation, we use the same number of iterations for both light and dense scanning

simulations, but we vary the length of the scanning duration and interleaving interval.

The purpose of this is to determine the ideal length of each to use that allows the mobile station

to have maximum throughput from the current base station it is connected to, while also being

able to scan for new and better base stations to connect to. For a stationary node, a long scanning

duration would be fairly useless. For a very mobile node, such as a vehicle, the scanning duration


40

could be crucial in maintaining a strong connection for delay and bandwidth sensitive services

such as voice-over-IP or video conferencing.

4.3.3 Method

In this scenario, we have a mobile station that travels along a path near 6 different base stations.

This is shown in the figure below.

Figure 4.3.3: Scenario 2 network topology

The green line is the trajectory of the mobile node. The yellow lines show the connection of each

base station to the internet (network cloud). The mobile station attempts to connect to the server

through the base stations

Table 4.3.3: The two sets of parameters used in light and dense scenario

Table 4.3.3 parameters of light

The scenario is run for 15 minutes in both cases. The statistics gathered to use for analysis are:

End-to-end Delay

Mobile Station SNR


41

Delay Jitter

Server Throughput

4.3.4 Results

We obtained the following results

Table4.3.4: Comparison between light and dense scanning results

Table4.3.4: Comparison between light and dense scanning results

Other results include SNR of mobile station (see figure 7), throughput and connection to the BS

ID (see figure 8). The SNR and the throughput go down when the mobile station is going

through scanning procedure. The SNR and throughput go up when the mobile station is

connected to a BS.


42

Figure 4.3.4: Signal to Noise Ratio

Figure 4.3.4: Traffic received – a comparison of the throughput


43

Figure 4.3.4: Time averaged WiMAX delay

Figure 4.3.4: Time averaged WiMAX packet jitter


44

4.4 Scenario 3

4.4.1 Objective

The purpose of this scenario is to analyze the range of connectivity between the mobilestation

and the base station as the mobile station starts moving away from one base station along a

certain trajectory, towards to the other BS, and then again moving away up to a certain proximity

and stopping.

4.4.2 Background

The radio transmission power of the mobile station changes as the station moves between base

stations, from one to another. Also the receive power varies for the base stations as the mobile

station moves towards them or away from them. As a result the connectivity is lost at some point

within the range between the two base stations and outside of the SNR threshold area.

4.4.3 Method

For this scenario, two base stations were chosen, distant from each other, as it can be seen from

Figure-10 below. Each base station itself is connected to an IP network via a router which itself

is connected to a server, supporting a variety of user applications (such asEmail and File

Transfer). The mobile station starts moving from the BS on the right tothe mid-point and then to

the BS on the left. This simulation also took approximately 1020 minutes which supported a 10

minute simulation run.

Figure 4.4.3: Ranging connectivity loss

4.4.4 Results

As a result of the simulation the following information illustrated in graphs below is captured. It

can be seen that as the MS moves away from the BS_1, the receive power drops down to zero

(see figure 12). All along the trajectory between the two base stations the receive power is down

for BS_1. However, the receive power approaches its peak value for the base station number 2 as

the MS reaches a certain proximity of BS_2. At the same time the radio transmission power has a


45

drop in a distance away from BS_1, and then no connectivity is achieved until the MS reaches

the threshold circle of the BS_2.

Figure 4.4.4: receive power and transmission power

Figure 4.4.4: traffic switch between BS_1 and BS_2


46

4.4.5 Discussion and Conclusions

In the first scenario, the minimum SNR ratios for each base station plays a critical role in the

variation of receive/transmit power for the MS, and as a result in the level of network availability

and network connectivity range. That is, as soon as the MS stands outside of the 27 dB SNR

(maximum threshold before scanning starts), the connectivity drop significantly and gradually

the disconnection from the network occurs.

In the second scenario, the results showed that using dense scanning affected the delay and jitter

of the mobile station. End-to-end delay increased from 48ms to 60ms and jitter increased from

22ms to 33ms when the scanning interval was increased from 4 to 20 frames. The throughput

also suffered when using the larger scan duration and this also decreased even more when the

SNR decreased below a particular value on the station’s path.

In the third scenario, and following the first and the second scenario, the radio transmission

power at the physical layer of WiMAX drops drastically, as a result of the low (almost zero)

SNR ratio. The disconnection continues to occur up to the point at which the MS enters the

threshold circle of the second base station

47

CHAPTER FIVE

Discussions and conclusions

Literature view

Measurement of QoS is essential for any Wimax / broadband wireless communication. In order

to ensure that a user- centric broadband experience becomes a reality, the broadband wireless

access networks must meet a number of Quality of Service (QoS) parameters, including

guaranteed throughput, and low delay, jitter and packet loss. Today in broadband wireless access

(BWA) the perception is that as adoption grows, so does the need for guaranteeing a good QoS.

The issue of QoS, therefore, has become a critical area of concern for suppliers of broadband

wireless access equipment and their customers too. Enforceable QoS is an essential foundation

for widespread acceptance of broadband wireless, since it allows for more efficient sharing of the

operator‘s infrastructure, as demand for capacity increases with subscriber take-up. Our paper

helps in analyzing various essential Wimax QoS parameters which are critical in determining the

performance of a Wimax network. A very low value of Jitter (approx. 1x10-9 seconds), delay (6

milliseconds) and packet loss (9%) is achieved, whereas a very high average value of throughput

and packet delivery is obtained using AODV protocol. From the results it could be interpreted

that as the mobile nodes keep on increasing, an optimum value of QoS parameters is obtained.

Therefore our paper helps in understanding these critical QoS parameters which helps in

improving performance for a given Wimax network.

Methodology

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 with high DSL unbundling costs or poor copper quality wich 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 endusers 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

48

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's IP capability enables it to provide a wide range of services to a wide variety of users.

With the gradual deployment of different WiMAX technology all over the world, WiMAX are

going through the evolution and adaptive processes to sustain with other technologies. A

WiMAX network connected to Internet has to cooperate with different access technologies and

determine the proper layer 2 and layer 3 mappings to provide E2E QoS services to the end users.

The NWG of WiMAX forum provides a network architecture model named NRM explaining the

functionalities and communications among different entities. In this chapter we

Addressed the physical connectivity requirements and techniques with respect to the

NRM mentioned in NWG. The set of possible required protocols to enable the E2E

QoS support has been discussed. We also presented the mapping of QoS parameters between

WiMAX and different access technologies like UMTS and Wi-Fi to provide assured QoS to the

end users. While in a network, the distinct means of QoS capabilities are present in different

layers, the network management is becoming more complex and difficult; and the network

operators require a strong coordination of QoS capabilities among different layers.

Data analysis and results

In the first scenario, the minimum SNR ratios for each base station plays a critical role in the

variation of receive/transmit power for the MS, and as a result in the level of network availability

and network connectivity range. That is, as soon as the MS stands outside of the 27 dB SNR

(maximum threshold before scanning starts), the connectivity drops significantly and gradually

the disconnection from the network occurs.

In the second scenario, the results showed that using dense scanning affected the delay and jitter

of the mobile station. End-to-end delay increased from 48ms to 60ms and jitter increased from

22ms to 33ms when the scanning interval was increased from 4 to 20 frames. The throughput

also suffered when using the larger scan duration and this also decreased even more when the

SNR decreased below a particular value on the station’s path.

In the third scenario, and following the first and the second scenario, the radio transmission

power at the physical layer of WiMAX drops drastically, as a result of the low (almost zero)

SNR ratio. The disconnection continues to occur up to the point at which the MS enters the

threshold circle of the second base station.

49

LIST OF ACRONYMS

0-9

2G: Second generation

3G: Third Generation A

AODV: Ad hoc on demand Distance Vector Routing

AES: Advanced encryption standard

ASN: Access Service Network

B

BTS: Base transmitter station

BS: Base Station

BE: Best effort

C

CCI: co-channel interference

CDMA: Code division multiplexing access

CTC: Convolution turbo codes

CAPEX: Operational expenditure

CPE: Customer-premises equipment

CCK: Complementary code keying

CPE: Customer Premise Equipment

CP: Cyclic prefix

CSN: Connectivity Service Network

D

DOCSIS: Data over cable service interface specification

DSL: Digital subscriber line

DSA: Dynamic Service Addition

DSC: Dynamic Service Change

DSD: Dynamic Service Deletion

Dl: Downlink

E

EAP: Extensible Authentication Protocol

F

FDD: Frequency division duplex

FBSS: Fast Base Station Switching

H

HHO: Hard Handoff

I

IFFT: Inverse Fast Fourier Transform

ITU: International Telecommunication Union

http://www.google.so/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&ved=0CC0QFjAB&url=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FCustomer-premises_equipment&ei=OKcxUcC4OYXktQb_roDoCg&usg=AFQjCNG4TGycsx_L0KdkczzlYEV2olNwkg&bvm=bv.43148975,d.Yms

50

ISPs: Internet Service Provider

ISI: Inter-Symbol Interference

L

LOS: line of sight

M

Man: Metropolitan area network

MAC: Medium access control

MPEG: Moving Picture Experts Group

Mimo: Multiple input multiple outputs

MDHO: Macro Diversity Handover

MS: Mobile station

MAP: Message authentication protocol

N

NLOS: Non line of sight

Ns: New simulation

NRM: Network Reference Model

O

OPEX: capital expenditure

P

PC: personal computer

PCMCIA: Personal Computer Memory Card International Association

PKM: privacy and key management

PDA: Personal digital assistant

PCB: Printed circuit board

PHY: physical layer

Q

QoS: Quality of Service

QPSK: Quadrature phase shift keying

OFDM: Orthogonal frequency division multiplexing

R

RF: Radio frequency

rtPS: Real time applications

rtps: Real-time polling service

http://www.google.so/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCgQFjAA&url=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FMoving_Picture_Experts_Group&ei=HagxUYOFApDktQbKh4CgDg&usg=AFQjCNGClmaAbv7samgfX8nDVE2GrE1_AQ&bvm=bv.43148975,d.Yms

http://en.wikipedia.org/wiki/Capital_expenditure

http://www.google.so/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CDIQFjAA&url=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FPersonal_digital_assistant&ei=a6gxUfWoFsWHtAbB7YGIBQ&usg=AFQjCNGc6b4ZWEgKjL_q55cUVU_2GQGIsQ&bvm=bv.43148975,d.Yms

http://www.google.so/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&ved=0CDMQFjAB&url=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FPrinted_circuit_board&ei=q6gxUe_wKYLcswal2oDwBg&usg=AFQjCNGb44L8QxNVIX5Eq9DHyq_g6OfzqQ&bvm=bv.43148975,d.Yms

51

S

SLAs Service-level agreement

STC: Space-time coding

SSID: Service set identifier

SS: Subscriber Station

SIM: Subscriber identifier module

SS: Subscriber stations

T

TDD: Time division duplex

TDMA: Time division multiplexing access

TRAI: Telecom Regulatory Authority of India

U

Ul: Uplink

UGS: Unsolicited grant service

V

VoIP: Voice of internet protocol

W

WiMAX: Worldwide Interoperability for Microwave Access

Wi-Fi: wireless fidelity

http://www.google.so/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&ved=0CDIQFjAB&url=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FService-level_agreement&ei=X6kxUf3UOIjcswaWhYHQCw&usg=AFQjCNHYbo3qW5AuRYtvBb77jhHKA_YQmg&bvm=bv.43148975,d.Yms

http://www.google.so/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CCgQFjAA&url=http%3A%2F%2Fwww.trai.gov.in%2F&ei=AqkxUbnAN4bkswbLuoHIBg&usg=AFQjCNFu1ZZmZ23o9LGJRCwbhrjs8vo0jg&bvm=bv.43148975,d.Yms

52

Bibliography

Books

Himanshu Gupta,Analysis Of WiMAX and Design of Transceiver,2ND Year ,B.Tech,IIT

Kharagpur,may,2007.

Sanida Omerovic,WiMax Overview, University ofLjubljana,Slovenia,project,feb,2009.

Rohit Talwalkar, Analysis of Quality of Service (QoS) in WiMAX network, project,

Florida Atlantic University, May, 2008.

IEEE 802.16-2004, “IEEE standard for Local and Metropolitan Area Networks —Part

16: Air Interface for Fixed Broadband Wireless Access Systems,” Oct.2004.

Bo Li, Hong Kong University of Science and Technology, a Survey on Mobile WiMAX,

IEEE Communications Magazine, December 2007.

Umar tariq , Analysis on fixed and mobile wimax ,MS in electrical engineering major in

telecommunication ,report,aug,2007.

Jingyi Shaoshao14@eecsEE228a,WiMax Scheduling, UC Berkeley May 2, 2006.

alvarion,wimax forum ,Radio Mobile Wimax,report,2006.

Wimax forum, mobile wimax -part1 technical overview and performance evaluation,

august, 2006.

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Websites

www.wimaxforum.org

www.tutorial-reports.com/wireless/wimax/tutorial.php

www.wimaxforum.org/news/downloads/supercomm_2005/WF_Day_in_a_Life_with

_WiMAX_ Final.

http://focus.ti.com/vf/docs/blockdiagram.tsp?blockDiagramId=6060&family=vf

WiMAX for NS-2 http://ndsl.csie.cgu.edu.tw/wimax_ns2.php

Design WiMAX (802.16) Network and Devices, Available at:

http://www.opnet.com/training/network_rd/modeler.html



http://www.wimaxforum.org/

http://www.tutorial-reports.com/wireless/wimax/tutorial.php

http://www.wimaxforum.org/news/downloads/supercomm_2005/WF_Day_in_a_Life_with

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http://ndsl.csie.cgu.edu.tw/wimax_ns2.php


Documents

Mini Project Qos Analysis of WiMAx