Download pdf - WIMAX QoS Seeker

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Quality of Service Seeker

By

Khaled Houssein

Wisam Salhab

A report submitted to the Department of Electrical Engineering in partial fulfillment of the

requirements for the degree of Master of Science in Electrical Engineering

Faculty of Engineering

University of Balamand

February 2013

Copyright © 2013, Khaled Houssein, & Wisam Salhab

All Rights Reserved

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University of Balamand

Faculty of Engineering

This is to certify that I have examined this copy of Master’s report by

Khaled Houssein

Wisam Salhab

And have found that it is complete and satisfactory in all the respects,

And that any and all revisions required by the final

Examining committee has been made.

COMMITTEE MEMBERS:

Approved:

Jihad Daba, Ph.D.

Supervisor

Approved:

Rafic Ayoubi, Ph.D.

First Moderator

Approved:

Issam Dagher, Ph.D.

Second Moderator

Date of report defense: January 12, 2013

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ACKNOWLEDGEMENTS

This report could not have been written if it were not for the contribution and

encouragement of various people and organizations.

The authors’ first wish is to thank the project supervisor, Dr. Jihad Daba for his advice and

support. Special gratitude goes to project moderators, Dr. Rafic Ayoubi and Dr. Issam Dagher.

This report would not have been written without the perseverance of the authors, and the

restless nights spent to finalize the project. Also, the encouragement and devotion of family and

friends should be mentioned who have helped a great deed.

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ABSTRACT

In the last free years, there has been important growth in wireless communications. The

Quality of Service has become an important consideration that supports many applications that

utilize the resources of a network. Some applications are the Voice over IP and the multimedia

services such as video streaming. WiMAX network is a new standard network which takes into

consideration the quality of service. This project refers to the measurement of network Quality of

Service (QoS) parameters of various real time applications like VoIP and video streaming.

The first phase of this project is the QoS parameter measurements. In this phase, a set of

QoS parameters are defined. These parameters are delay, delay variation (jitter) and packet loss

probability . They are used in the development of program. Then the “QoS Seeker application”

developed in this project is presented, including its principle . The following contents give a

collection and analysis of results of the measurements of QoS parameters using the “QoS Seeker

program”.

The second phase is the video streaming and VoIP call simulation. In this part, elements

of general video and VoIP applications are introduced. The parameters that specify the quality

of service of the network , such as, throughput, packet loss, jitter and latency , are analyzed for

different times of services

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Table of Contents

TABLE OF CONTENTS ............................................................................................................................................ 5

CHAPTER 1 .............................................................................................................................................................. 12

OVERVIEW OVER WIMAX .................................................................................................................................. 12

1.1. INTRODUCTION .............................................................................................................. 12

1.2. FIXED WIMAX (IEEE802.16D) .................................................................................... 13

1.3. MOBILE WIMAX (IEEE802.16E) ................................................................................ 14

1.4. ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING (OFDM) ................................ 15

1.5. ORTHOGONAL FREQUENCY-DIVISION MULTIPLE ACCESS (OFDMA) ....................... 17

1.6. WIMAX ARCHITECTURE .............................................................................................. 17

1.6.1. WiMAX Architecture Parts ................................................................................................................ 18

1.6.2. WiMAX Protocol ............................................................................................................................... 20

1.7. PHYSICAL LAYER OF WIMAX ...................................................................................... 21

1.7.1. Modulation Schemes .......................................................................................................................... 22

1.7.2. WiMAX Transmitters ......................................................................................................................... 22

1.7.3. Frequency Division Duplexing (FDD) .............................................................................................. 23

1.7.4. Time Division Duplexing (TDD) ....................................................................................................... 24

1.8. MAC LAYER IN WIMAX ............................................................................................... 24

1.9. WIMAX PHY FRAME ................................................................................................... 25

1.9.1. Downlink Sub frame .......................................................................................................................... 26

1.9.2. Uplink Sub frame ............................................................................................................................... 26

2. WIMAX VERSUS WI-FI .................................................................................................... 27

CHAPTER 2 .............................................................................................................................................................. 28

QUALITY OF SERVICE IN WIMAX NETWORKS ........................................................................................... 28

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2.1. QOS DEFINITION ........................................................................................................... 28

2.2. QOS PARAMETERS ......................................................................................................... 28

2.2.1. Bandwidth .......................................................................................................................................... 28

2.2.2. Latency .............................................................................................................................................. 29

2.2.3. Jitter or PDV ..................................................................................................................................... 29

2.2.4. Packet Loss ........................................................................................................................................ 29

2.3. APPLICATIONS FOR QUALITY OF SERVICE ................................................................... 30

2.4. WIMAX QOS CLASSES ................................................................................................. 30

CHAPTER 3 .............................................................................................................................................................. 32

VOIP / MULTIMEDIA OVER WIMAX ................................................................................................................ 32

3.1. VOICE OVER INTERNET PROTOCOL (VOIP) .................................................................... 32

3.1.1. Definition ................................................................................................................................................ 32

3.1.2. VoIP Network Connections ..................................................................................................................... 32

3.1.3. Real Time Protocol ................................................................................................................................ 34

3.1.4. Codec ...................................................................................................................................................... 35

A. G.729 Codec ............................................................................................................................................................... 35

B. G.711 Codec ............................................................................................................................................................... 35

3.1.5. VoIP QoS ............................................................................................................................................... 36

Measurements .................................................................................................................................................................. 36

3.2. IP MEDIA SUBSYSTEM SERVICES - IMS ......................................................................... 37

3.2.1. Video Streaming ...................................................................................................................................... 37

3.2.2. IPTV ...................................................................................................................................................... 38

CHAPTER 4 .............................................................................................................................................................. 39

SIMULATION ENVIRONMENT AND CASES STUDIED ................................................................................. 39

4.1. SIMULATION DETAILS ..................................................................................................... 39

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4.2. WINDOWS 7 LOCATION SENSOR ...................................................................................... 39

4.3. DESIGN OF WIMAX QOS SEEKER APPLICATION .......................................................... 40

4.3.1. WiMAX QoS Seeker ............................................................................................................................... 41

4.4. ANALYSIS STEPS OF QOS SEEKER .................................................................................. 45

4.4.1. Getting the GPS Location ...................................................................................................................... 45

4.4.2. Measuring QoS parameters and Calculating MOS ................................................................................ 46

QOS Parameters ............................................................................................................................................................... 46

Latency or Average Delay ......................................................................................................................................... 47

Jitter or Delay Variation ........................................................................................................................................... 48

Packet Loss ................................................................................................................................................................. 49

Mean Opinion Score (MOS) ............................................................................................................................................ 49

4.4.3. Updating the Map ................................................................................................................................... 52

WCF Service .............................................................................................................................................................. 53

Mercator Map projection ......................................................................................................................................... 53

CHAPTER 5 .............................................................................................................................................................. 57

IMPLEMENTATION RESULTS ............................................................................................................................ 57

5.1. TEST FOR STATIC WIMAX USER .................................................................................... 57

5.1.1. Results for VOIP traffic using G.711 codec ........................................................................................... 57

A. Bandwidth Availability ........................................................................................................................................... 57

B. Jitter Performance ................................................................................................................................................... 59

C. Latency Performance .............................................................................................................................................. 61

D. Packet Loss Performance ........................................................................................................................................ 62

E. Overall VoIP performance (MOS value) ................................................................................................................ 63

5.1.2. RESULTS FOR VIDEO STREAMING ................................................................................ 64


B. Jitter Performance ................................................................................................................................................... 67

C. Latency Performance .............................................................................................................................................. 68

D. Packet Loss Performance ........................................................................................................................................ 69

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5.2. TEST FOR MOBILE WIMAX USER .................................................................................... 70

5.2.1. Results for VOIP traffic using G.711 codec ............................................................................................ 70


B. Jitter Performance ....................................................................................................................................... 72

C. Latency Performance .................................................................................................................................. 73

D. Packet Loss Performance ........................................................................................................................... 74

E. Overall VoIP performance (MOS value) .................................................................................................... 74

CHAPTER 6 .............................................................................................................................................................. 76

CONCLUSION AND FUTURE WORK ................................................................................................................. 76

6.1. CONCLUSION ...................................................................................................................... 76

6.2. FUTURE WORK ................................................................................................................. 77

LIST OF REFERENCES .......................................................................................................................................... 78

APPENDIX A1........................................................................................................................................................... 80

EQUIPMENTS USED ............................................................................................................................................... 80

APPENDIX A2............................................................................................ ERROR! BOOKMARK NOT DEFINED.

PROJECT CODES ..................................................................................... ERROR! BOOKMARK NOT DEFINED.

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LIST OF TABLES

TABLE 1 : WIMAX VS. WI-FI ....................................................................................................................................... 27

TABLE 2 : QOS CLASSES .............................................................................................................................................. 31

TABLE 3 : G.711 CODEC SPECIFICATION ...................................................................................................................... 35

TABLE 4 : MOS QUALITY RATING ................................................................................................................................ 36

TABLE 5 : MOS COLORS REPRESENTATION .................................................................................................................. 45

TABLE 6 : FITTING PARAMETERS FOR CODEC G.711 ANDG.729 ................................................................................... 50

TABLE 7 : DOWNLOAD AND UPLOAD RATES FOR VOIP ................................................................................................ 58

TABLE 8 : VIDEO STREAMING DOWNLOADS AND UPLOADS RATES .............................................................................. 65

TABLE 9 : MOBILE DOWNLOADS AND UPLOADS RATES ................................................................................................ 70

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LIST OF FIGURES

FIGURE 1 : WIMAX STANDARDS ................................................................................................................................. 13

FIGURE 2 : FIXED WIMAX ARCHITECTURE ................................................................................................................. 14

FIGURE 3: 802.16 STANDARDS ..................................................................................................................................... 15

FIGURE 4 : MOBILE WIMAX ARCHITECTURE .............................................................................................................. 15

FIGURE 5: OFDM ARCHITECTURE ............................................................................................................................... 16

FIGURE 6 : HOW ICI IS FOUND ....................................................................................................................................... 16

FIGURE 7 : OFDM SYMBOL USERS .............................................................................................................................. 17

FIGURE 8 : NETWORK ARCHITECTURE OF WIMAX ...................................................................................................... 18

FIGURE 9 : PHYSICAL LAYERS OF WIMAX ................................................................................................................... 20

FIGURE 10 : BLOCK DIAGRAM OF WIMAX TRANSMITTER ............................................................................................ 23

FIGURE 11 : BLOCK DIAGRAM OF WIMAX RECEIVER .................................................................................................. 23

FIGURE 12: NETWORK ENTRY PROCEDURE .................................................................................................................. 25

FIGURE 13 : WIMAX PHY FRAME ............................................................................................................................... 25

FIGURE 16 : VOIP NETWORK ........................................................................................................................................ 33

FIGURE 17 : TCP/IP PROTOCOLS .................................................................................................................................. 33

FIGURE 18 : RTP DATAGRAM FOR VOIP ...................................................................................................................... 34

FIGURE 22: IPTV NETWORK ......................................................................................................................................... 38

FIGURE 23 : ENABLE GEOSENSE SENSOR ...................................................................................................................... 40

FIGURE 24 : MAIN FORM OF QOS SEEKER APPLICATION .............................................................................................. 41

FIGURE 25 : VOIP MAP FORM ...................................................................................................................................... 43

FIGURE 26 : GETTING THE USER GPS LOCATION STEP ................................................................................................. 46

FIGURE 27 : LATENCY IN NETWORK ............................................................................................................................. 47

FIGURE 28 : R-FACTOR RATING WITH MOS SCORE MAPPING AND USER SATISFACTION LEVEL ..................................... 51

FIGURE 29 : MEASURING QOS PARAMETERS STEP ....................................................................................................... 52

FIGURE 30 : EL MINA MAP ........................................................................................................................................... 54

FIGURE 31 : UPDATED MAP .......................................................................................................................................... 56

FIGURE 32 : VOIP DOWNLOAD RATES PLOT ................................................................................................................. 58

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FIGURE 33 : VOIP UPLOAD RATES PLOT ...................................................................................................................... 59

FIGURE 34 : VOIP MEASURED JITTER ........................................................................................................................... 60

FIGURE 35 : VOIP MEASURED LATENCY ...................................................................................................................... 61

FIGURE 36 : VOIP MEASURED PACKET LOSS ............................................................................................................... 62

FIGURE 37 : MOS VALUES PLOT .................................................................................................................................. 63

FIGURE 38 : VIDEO STREAMING DOWNLOADS RATES PLOT.......................................................................................... 65

FIGURE 39 : VIDEO STREAMING UPLOADS RATES PLOT ............................................................................................... 66

FIGURE 40 : MEASURED JITTER VIDEO STREAMING ..................................................................................................... 67

FIGURE 41 : MEASURED LATENCY VIDEO STREAMING ................................................................................................ 68

FIGURE 42 : PACKET LOSS VIDEO STREAMING ............................................................................................................. 69

FIGURE 43 : MOBILE DOWNLOAD RATES PLOT .............................................................................................................. 71

FIGURE 44 : MOBILE UPLOAD RATES PLOT .................................................................................................................... 71

FIGURE 45 : MEASURED MOBILE JITTER ....................................................................................................................... 72

FIGURE 46 : MEASURED MOBILE LATENCY .................................................................................................................. 73

FIGURE 47 : MEASURED MOBILE PACKET LOSS ............................................................................................................ 74

FIGURE 48 : MOBILE MOS VALUES ............................................................................................................................... 75

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Chapter 1

Overview over WiMAX

1.1. Introduction

WiMAX stands for Worldwide Interoperability for Microwave Access, joins the

technology of Wi-Fi and high rate internet to offer high-speed internet across long distances. It

can be used as a substitute to the current cabled access networks such as optical fibers and

Digital Subscriber lines (DSL). Also it provides broadband services for people who can’t manage

wired broadband services. It satisfies different types of access, such as fixed, portable and mobile

access. In order to use these types, two versions are presented, the IEEE802.16d which known as

Fixed WiMAX and IEEE802.16e that is known as Mobile WiMAX. WiMAX radio could be able

to service data rates up to 70 Mbps and operating channel bandwidth from 1.25 MHZ up to 20

MHZ. It should also support access to a distance of 50 km between base station and the user.

WiMAX sustains Non Line of Sight (NLOS) communication. The frequency bands that operate

for WiMAX are 2.5GHz, 3.5 GHz and 5.8 GHz. WiMAX can be used for various applications

such as broadband connections, hotspots and high speed connectivity. The WiMAX base station

covers 5 to 10 km range.

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Figure 1 : WiMAX standards

1.2. Fixed WiMAX (IEEE802.16d)

It is used to optimize for fixed access and based on orthogonal frequency division

multiplexing (OFDM). Also, it is designed to operate in a range of 10 to 66 GHz spectrum and

gives the specifications of physical layer (PHY) and medium access control (MAC) of the air

interference systems. The transmission line needed is NLOS with the base station. It is found for

the broadband wireless access at high speed and it is easily installed. The features of

IEEE802.16d are:

Non Line of sight service

Multiple radio modulation options

Quality of service features

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Figure 2 : Fixed WiMAX Architecture 1.3. Mobile WiMAX (IEEE802.16e)

It is used to optimize for mobile access and based on scalable orthogonal frequency

division multiple accesses. It delivers the broadband data to a moving terminal such as laptops

with integrated WiMAX modem.

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Figure 3: 802.16 standards

Figure 4 : Mobile WiMAX Architecture

1.4. Orthogonal Frequency Division Multiplexing (OFDM)

The Orthogonal Frequency Division Multiplexing is used to provide the operator to

overcome the Inter-Symbol interference (ISI) by the channel and the difficulties of Non-Line-of-

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Sight (NLOS) transmitting in a better effective approach. The ISI happens when the delay spread

of channel is greater than the symbol time.

Figure 5: OFDM Architecture

Because of that OFDM divides the data into parallel paths and each one has a multiple

separate carrier with low rate. Then, signals are sent by different frequencies to each user with a

various number of cycles in a symbol period, and data is carried by varying the phase of each

subcarrier.

Figure 6 : how ICI is found

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1.5. Orthogonal Frequency-Division Multiple Access (OFDMA)

The Orthogonal Frequency-Division Multiple Access (OFDMA) has multiple sub carriers

and each one is divided into different groups. Each group is divided into sub channels. This will

result to the user to be found in one or more sub channels and lower the data transmission.

Figure 7 : OFDM Symbol Users

The cyclic prefix (CP) is the repetition of the last cycle of the last data block that was sent,

which removes the ISI in the case if the CP duration is larger than the channel delay spread.

Although the CP will reduce the bandwidth efficiency since the OFDM has high edges which

will result in transmitting the channel bandwidth to data transmission.

1.6. WiMAX Architecture

The WiMAX Network Working Group (NWG) is responsible for full WiMAX end to

end network development since IEEE 802.16 only provide the air interference for WiMAX. The

NWG defines the network architecture based on an IP core network which is chosen by the

Internet Service Provider (ISP) to support fixed and mobile deployments.

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The figure below shows the network architecture of WiMAX:

Figure 8 : Network Architecture of WiMAX

1.6.1. WiMAX Architecture Parts

The WiMAX architecture is composed of the following parts:

a. Mobile stations (MS): it is the user equipments that locate the area of the user and

provide the wireless connectivity between one or more hosts and the WiMAX

network.

b. Base Station (BS): it is responsible for air interference between the MS and users.

It includes functions such as handoffs, tunnel establishment, radio resource

management, QoS policy, DHCP proxy, and key and session management. Also it

is responsible for the downlink and uplink schedules. Every BS is symbolizing one

sector with one frequency assignment.

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c. Access Service Network (ASN): it forms the radio access network using OFDMA.

ASN includes base stations (BS) and access gateway ASN-GW. ASN should

include some functions such as: 802.16 layer 2 connectivity with WiMAX MS,

transfer authentication and authorization messages to WiMAX subscribers

network for authentican, and authorization, network discovery and selection of

WiMAX network, establishing layer 3 connectivity with MS, radio resource

management, QoS and policy management. It also supports multicast and

broadcast control.

d. ASN Gateway (ASN-GW): It is connected to one device such as BS. It is

connected to the ASN and it’s responsible for routing or bridging. Also include

the mapping to the IP network, and responsible for the handover.

e. Connectivity Service Network (CSN): It provides the IP connectivity and the IP

core network functions. It includes network elements such as routers, user

databases, internetworking gateway devices. Also provides functions as: Internet

access, MS IP address, admission control based on user subscription, WiMAX

subscriber billing, inter ASN mobility.

f. Reference Point (RP): are the links between every component of the network

architecture of WiMAX.

R1: includes protocols between MS and ASN.

R2: includes protocols between MS and CSN for authentication and

authorization and IP configuration.

R3: includes protocols between ASN and CSN that provides tunneling.

R4: includes protocols that manage between MS and ASN-GW.

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R5: includes protocols that support roaming between CSN and NSP.

R8: used to maintain the hangover for fast transfer between BSs.

1.6.2. WiMAX Protocol

WiMAX protocol is responsible for schedule management and resource allocation. The

MAC layer of WiMAX are divided into four parts which are: Convergence sub layer, MAC

common part sub layer, security sub layer, and PHY layer.

Figure 9 : Physical layers of WiMAX

a. Convergence sub layer (CS): it is an interface to the WiMAX MAC. It is presented

by the MAC CPS through Mac Service Access Point. It provides the asynchronous

transfer mode (ATM) CS and it supports IP version 4 or version 6. Also it provides

classifying and mapping the MSDUs into connection identifier which is a function of

Quality of Service mechanism.

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b. MAC common part sub layer: It is responsible for the connection establishment and

bandwidth allocation. Connection establishment are done when messages sent from

MS to BS, and when the connection is acceptable the message will be transferred and

the data will be transmitted.

c. Security sub layer: it is responsible for authentication, secure exchange, and

encryption. Encapsulation protocol is used for encrypting data packets. In addition to

the authentication protocol, the Privacy Key Management (PKM) protocol is

responsible for security distribution of key data from BS to MS. This is done by

adding digital certificate based authentication to the PKM.

d. PHY layer: it is responsible for the uplink and downlink connections. It gives

information of type of the signal, modulation and demodulation types, and the

transmission power.

1.7. Physical Layer of WiMAX

In the 802.16 standard there are five physical interfaces that are introduced below:

1. Wireless MAN-SC (sub carrier) that have a bandwidth with range 10-66 GHz.

2. Wireless MAN-SCA (sub carrier) that have a bandwidth with range 2-11 GHz.

3. Wireless MAN-OFDM uses OFDM that have a bandwidth with range 2-11 GHz.

4. Wireless MAN-OFDMA uses OFDM and OFDMA that have a bandwidth with range

2-11 GHz.

5. Wireless HUMAN the Wireless MAN air interface supports two FEC schemes which

are the Reed Solomon only and Reed Solomon concatenated with convolution code

(RS-CC).

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The Concatenated coding uses inner convolution codes the same as used in the 802.11.

FEC is necessary for OFDM models because it is used for the bit errors that are unavoidable due

to the deep fades of the channel. After the completion of RS-CC, all data bits are block

interleaved since WiMAX-OFDM 802.16 or WiMAX-OFDMA 802.16a are applied. It is

resistant to the long multipath delays that occur in long range, and NLOS.

1.7.1. Modulation Schemes

The four different modulation schemes are:

a. 16-QAM: used to maximize link throughput

b. 64-QAM: used to maximize link throughput

c. BPSK: used for robustness and reliability

d. QPSK: used for robustness and reliability

1.7.2. WiMAX Transmitters

The WiMAX transmitter can be expressed by

a. Randomizer

b. Forward error correction (FEC)

c. Interleaver

d. Modulator

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Figure 10 : Block diagram of WiMAX transmitter

At the other end, at the receiver side the same operations are applied but in the reverse

order.

Figure 11 : Block diagram of WiMAX Receiver

1.7.3. Frequency Division Duplexing (FDD)

A fixed frame is used for both downlink and uplink, while both are located on separate

frequencies. The full duplex and the half duplex can be used. The full duplex SS can be used to

sends and receives simultaneously, and can keep on listening to the downlink channel. Whereas

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the half duplex SS cannot send and receives at the same time and it can listen to the downlink

channel only if it is not transmitting on the uplink.

1.7.4. Time Division Duplexing (TDD)

The frame has a fixed duration and has a frame for the uplink channel and a frame for the

downlink channel which are not necessary equal. In addition, both channels have the same

frequency. The scheduler is responsible for the splitting between the uplink and the downlink,

and it is widely used in mode of duplexing.

1.8. Mac Layer in WiMAX

The MAC layer is divided into four parts: Convergence sub layer (CS), common part sub

layer (CPS), security sub layer (SS) which are explained in the next chapter. The MAC layer in

WiMAX is responsible for bandwidth reservation and resource allocation. In order for a new

SS/MS to register in the network, the system has the following procedure:

1. Check for downlink channel and connect with the BS. Then the SS/MS start to

synchronize the time and frequency parameters with the BS.

2. It provides the time offset, frequency and transmitted power level in order for the SS/MS

to communicate with the BS.

3. The SS/MS sends the IP version, IP management mode, and MAC CRC to the BS and

when the BS recognizes this manageability a connection identifier (CID) is assigned.

4. Create IP connectivity using DHCP.

5. A secondary connection is created, that is secured, when the registration is done, which

uses IP connectivity and for TFTP file configuration loading.

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6. The network exchanges the information about the service flows between the BS and

SS/MS.

Figure 12: Network Entry Procedure

1.9. WiMAX PHY Frame

The PHY frames are split into downlink and uplink sub frames. An uplink sub frame is

separated from a downlink sub frame by a TTG gap, and from the downlink sub frame by a RTG

gap.

Figure 13 : WiMAX PHY frame

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1.9.1. Downlink Sub frame

The downlink PHY frame is divided into:

Preamble: it is used for synchronization

Frame Control Head (FCH): gives the frame configuration information such as

coding schemes, and available sub channels.

Downlink map (DL-MAP): gives the burst profile, location, duration of zones.

Uplink map (UL-MAP): gives the sub channel and slot allocation.

Downlink channel descriptor (DCD): it is sent by the BS that indicates the

characteristics of a downlink frame.

Uplink channel descriptor (UCD): it is sent by the BS that indicates the

characteristics of an uplink frame.

Burst #: Time division multiplexing (TDM) portion

The DL sub frame is divided into burst profiles which transmit all the traffic consecutively.

Also, The DL-MAP tells all the SS to which part of the frame they should listen to.

1.9.2. Uplink Sub frame

The Uplink sub frames are divided into:

Contention slots that allows initial ranging.

Contention slots that allows bandwidth requests.

PHY PDU #: Are uplink sub frames that are transmitted from different SSs and it can

sends an SS MAC message.

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2. WiMAX versus Wi-Fi

WiMAX is being established from the same concept of Wi-Fi. But the WiMAX works on

a larger scale and larger speed. The following steps will show the difference factors between the

two standards.

a. IEEE standards: WiMAX is based on IEEE802.16 whereas Wi-Fi is based on 802.11.

b. Range: WiMAX can reach a range up to 64 kilometers (40 miles) with a speed of 70

Mbps. While Wi-Fi can provide only a local network for a range up to 40 meters with a

speed of 54 mbps.

c. Bit rate: WiMAX works at 5bps/Hz and can reach up to 100 mbps. With respect to Wi-

Fi it works at 2.7 kbps/Hz and can reach up to 54 mbps.

d. Scalability: It is designed to provide hundreds of routers with a large number of

subscribers, with a channel size range from 1.5 MHz to 20 MHz However Wi-Fi works

for LAN applications that provide one to ten routers with a single user for each router,

with a range of 20MHz.

WiMAX Wi-Fi (802.11a) Wi-Fi (802.11b)

Application Broadband wireless Access Wireless LAN Wireless LAN

Frequency 2 GHz – 11 GHz 2.4 GHz 2.4 GHz

Half/Full duplex Full Half Half

Radio Technology OFDM (128 channels) OFDM 64channels Direct sequence

Bandwidth <= 5 bps/Hz <= 2.7 bps/Hz <=0.44 bps/Hz

Modulation BPSK,QPSK,16,64, 256 QAM BPSK,QPSK,16,64 ,AM QPSK

Mobility Mobile WiMAX (802.16e) Not Yet Not Yet

Access Protocol Request/Granted CSMA/CA CSMA/CA

Table 1 : WiMAX vs. Wi-Fi

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Chapter 2

Quality of Service in WiMAX Networks

2.1. QoS Definition

The quality of service, in the field of telephony, was defined by the ITU in 1994. The

service response time, loss, signal-to-noise ratio, echo, interrupts, frequency response and many

factors are used by the Quality of service mechanisms to specify the aspects of the connection.

In the field of packet-switched telecommunication networks and computer networking, the

Quality of service is the ability to send and receive a packet successfully between many

applications, data flows, users, and to assure a good performance to the network.

2.2. QoS Parameters

In VoIP, quality means the capability to have a discussion and listen clearly without any

noise. In a packet data network, there are many factors that specify the performance of the

WiMAX QoS and the network. These most common factors are :

Bandwidth

Latency

Jitter

Packet Loss

2.2.1. Bandwidth

Bandwidth is probably the most basic QOS parameter for many end users. It is obviously

limited by the number of active clients in parallel and by the physical-layer channel between the

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base station and the client terminal. In general, if the bandwidth of the system is big enough,

some of the other QOS parameters will not be an issue.

2.2.2. Latency

In WiMAX, it is the time that it takes from the beginning of sending data until it arrives

at its destination. As far as latency is concerned, the WiMAX system can be divided into these

main elements:

o Over the IP network

o From the base station to the end user over the WiMAX radio interface and vice

versa.

2.2.3. Jitter or PDV

In WiMAX System, jitter is a measure of the variability over time of the packet latency

across a network. There is no jitter for the network with constant latency. The term Jitter has

another standard term, the packet delay variation (PDV). PDV is a significant factor in

estimating of network performance and the Quality of Service.

2.2.4. Packet Loss

Packet loss specifies the loss of data packets during transmission over a network. Packet loss

occurs when one or more packets fail to reach the destination. This can produce significant

problems, especially in some applications such as Voice over Internet Protocol (VOIP), where

information lost cannot be recovered. In some situations, it may be possible to correct for packet

loss errors and allow data to be reassembled as it was intended.

In audio communications, such as VoIP, it can cause jitter and gaps in received speech.

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There are many different causes for packet loss. In some cases, the signal may corrupt over time.

In other cases, hardware problems could cause packet loss. Other reasons include networks that

have too much demand and corrupted packets.

2.3. Applications for Quality of Service

There are certain types of network that desire or require a defined Quality of Service such

as:

1. Streaming Media

Streaming media is video or audio content played immediately over the internet. The user

does not have to download the file to play it. The media can play as it arrives because it is

sent in a continuous stream of data. There are specific applications that require QoS such

as IPTV.

2. Voice over IP (VoIP)

VoIP is a digital network system that allows people to make telephone calls over Internet rather

than analog land lines

3. Videoconferencing

Videoconferencing or video teleconference is a technology that allows users in different

locations to hold face-to-face meetings without having to move to a single location.

2.4. WiMAX QoS Classes

In order to categorize the different types of quality of service, there are five WiMAX QoS

classes that have been defined. Four classes of service (UGS, rtPS, nrtPS and BE) are defined in

IEEE 802.16d (fixed WiMAX), and IEEE 802.16e (Mobile WiMAX) introduces another QoS

class called Extended Real-Time Polling Service (ertPS).

The table below shows these Classes :

31

Table 2 : QoS Classes

32

Chapter 3

VoIP / Multimedia over WiMAX

3.1. Voice over Internet Protocol (VoIP)

3.1.1. Definition

The Voice over Internet Protocol (VoIP), also called IP Telephony, is rapidly becoming a

well-known term and technology that is infecting government organizations, enterprise, and

education. VoIP is a technology that allows people make telephone calls over computer networks

like the Internet. VoIP converts analog voice signals into digital data packets and supports real-

time, two-way transmission of conversations using Internet Protocol (IP). It is designed to

replace the legacy TDM technologies with an IP-based data network. The IP data packets over a

LAN and/or WAN network will carry the digitized voice. To Install and test the VoIP network of

IP phones, gateways and servers requires new tools and expanded knowledge.

The standard speech transmission protocol used with VoIP networks is the Real Time

Protocol (RTP). The speech is digitized and transmitted using packets through the IP network.

Multiple packets are required to carry a single spoken word. The voice is digitized using one of

the G.7xx standards.

3.1.2. VoIP Network Connections

A VoIP connection is well-known between PC to PC, phone to phone or phone to PC as

shown in the figure below.

33

Figure 14 : VoIP Network

TCP/IP Protocol

The Transmission Control Protocol and Internet Protocol (TCP/IP) is a set of protocols that

provides end-to-end connectivity specifying how data should be formatted, addressed,

transmitted, routed and received at the destination. TCP/IP protocol consists of four layers.

Figure 15 : TCP/IP Protocols

34

The role of the TCP is sending the packets over the Internet protocol and reassembling

them at the destination end. In case of lost or corrupted packet received and If the packets arrive

out of order the TCP sends an acknowledgement to the transmitter which then resend the wanted

packets after reordering them again. The TCP protocol ensures reliable delivery of packets over

the internet.

3.1.3. Real Time Protocol

The Real Time Protocol (RTP) is designed to be used inreal-time applications like audio

and video streams. It uses the User Datagram Protocol (UDP) rather than TCP to reduce the

delay for these real time applications. RTP packet encapsulates its payload to include a sequence

number and a timestamp to keep track of the real time information.

Figure 16 : RTP Datagram for VoIP

RTCP – RTP Control Protocol

The Real Time Transport Control Protocol (RTCP) is special messages that are used by RTP

to exchange real time reports and statistics.

The RTCP packets help to monitor the performance and Quality of Service (QoS) of real time

data since the reports share information like total number of packets sent, total packets received

and lost and also the inter-arrival jitter.

35

3.1.4. Codec

The Codec is a coder/decoder. It converts the analog signal into digital bits and outs

them at a constant data rate. Codec is also known as Compressor/Decompressor since while

sending the data bits, it compresses them to save the bandwidth.

A. G.729 Codec

G.729 is ITU-T recommendation for the coding of speech signals at 8kbps data rate using

Conjugate Structure-Algebraic Code Excited Linear Prediction (CS-ACELP). G.729 uses 8000

samples per second while using 16 bit linear PCM as coding method. Data compression delay is

10ms for G.729; also G.729 is optimized to use with actual voice signals. Also, the lower

bandwidth of 8kbps leads to use the G.729 in Voice over IP (VoIP) applications easily.

B. G.711 Codec

G.711 is an ITU –T standard and is primarily referred to as telephony codec. Formal

name for G.711 is Pulse Code Modulation (PCM) and it represents speech sampled at 8000

Samples / second.

Table 3 : G.711 Codec Specification

36

3.1.5. VoIP QoS

Measurements

The techniques used to measure the voice quality of a VoIP call are the Mean Opinion Score

(MOS) and Perceptual Speech Quality Measurement (PSQM).

Mean Opinion Score (MOS)

Mean Opinion Score (MOS) is a numerical method of expressing voice and video quality.

MOS estimating follows the techniques specified in ITU-T P.800. In voice and video

communication, quality usually dictates whether the experience is a good or bad one. MOS is

expressed in one number, from 1 to 5, 1 being the worst and 5 the best. MOS is quite

subjective, as it is based figures that result from what is perceived by people during tests. A

definition of the MOS and the scores is given below.

Rating Voice quality Level of distortion

5 Excellent Imperceptible

4 Good Just perceptible but not annoying

3 Fair Perceptible & slightly annoying

2 Poor Annoying but not objectionable

1 Bad Very annoying and objectionable

Table 4 : MOS Quality rating

Perceptual Speech Quality Measure(PSQM)

This method uses artificial speech, to present numeric values of approximate

speech clearness taking into account effects such as noise, coding errors, packet

reordering, phase jitter, and excessive bit error rate. PSQM=0 signifies no impairment,

while PSQM=6.5 indicates that the signal is totally unusable.

37

3.2. IP Media Subsystem Services - IMS

Today WiMAX is the only network standard which is able to provide the Quadruple

play Technologies ( Data, Voice, Video, Mobility)) using a single network. these services are

referred to as IP Media Subsystem Services – IMS.

3.2.1. Video Streaming

This type of video is sometimes referred to as on-demand video. It is a one-way video.

Streaming video does not have inflexible delay and jitter requirements because the hard drive

and memory (DRAM) of the receiving station provides a very large jitter (playout) buffer to

ensure playback of streaming video is smooth and gapless. www.youtube.com is an example of a

streaming video application.

When measuring the QoS needs of Streaming Video traffic, the following are

recommended:

• Loss should be no more than 5 %.

• Latency should be no more than 4-5 seconds (depending on video application buffering)

• There are no significant jitter requirements.

The Streaming Video applications have more compassionate QoS requirements because they are

delay-insensitive where the video can take several seconds to cue-up and they are largely jitter-

insensitive due to application buffering. However, Streaming Video may contain valuable

content, such as e-learning applications or multicast company meetings, and therefore may

require service guarantees.

38

3.2.2. IPTV

The process of IPTV process involves receiving the programs directly from the

broadcasters after encoding it into MPEG-2 format at a constant bit rate. The MPEG-2 stream is

encapsulated into UDP/IP and is then sent as individual multicast streams to satellite uplink.

Figure 17: IPTV network

QoS Elements

We can divide Quality of Service into the following three layers:

Application level Quality of Service: specifies those parameters related to user

requirements and expectations. Frame size, sample rate, image and audio clarity are some

parameters of this level.

System level Quality of Service: includes operating system and CPU requirements, such

as processing time, CPU utilization, and media relations like synchronization.

Network level Quality of Service: defines communication requirements, such as

throughput, delay, jitter, loss, and reliability.

39

Chapter 4

Simulation environment and cases studied

4.1. Simulation Details

In order to obtain the optimal QoS, the QoS Seeker attempts to automatically inform the

user of the location he should go to. To achieve this goal, the QoS Seeker continuously collects

position information and QoS metrics - such as packet loss, packet delay, jitter, and received

signal strength, from all connected users. The positioning information is obtained from GPS

USB devices embedded on mobile laptop and also using a Windows 7 Location Sensor called

Geosense. This information is sent to a web service that save all users’ data (longitude, latitude

and the QOS Metrics) in order to evaluate the future QoS metrics at all locations within the area

covered by the WiMAX network.

4.2. Windows 7 Location Sensor

The Windows 7 operating system provides built-in support for sensor devices. This includes

support for location sensors, such as GPS devices. The Windows Sensor and Location platform

organizes sensors into categories in which the location devices make up one especially

interesting category. Built on the Sensor API, the Location API provides an easy way to retrieve

data about geographic location while protecting user privacy. So far, most people are familiar

with global positioning systems (GPS). In Windows, a GPS sensor is part of the Location

category.

There are many windows location sensors. Geosense is a Windows Sensor that provides the

Location and Sensors platform in Windows 7 with precise and sensibly positioning information

without requiring or the assistance of GPS hardware. Geosense is designed to use a hybrid mix

40

of geolocation service providers and geolocation methods to pinpoint the most accurate location

information possible - including but not limited to Wi-Fi triangulation, cell tower triangulation

and IP lookup.

Figure 18 : Enable Geosense Sensor

4.3. Design of WiMAX QoS Seeker Application

The test setup consisted of a windows 7 laptop that had a VoIP call established with

another one in different location. The laptop on which the WiMAX QoS Seeker application

is downloaded is fixed while the user on the other laptop can be mobile or fixed during the

VoIP call. The MOS subjective tests were performed for VoIP call using both the codec’s

G.711 and G.729.

41

4.3.1. WiMAX QoS Seeker

Skype is the VoIP client used in the project. The WiMAX QoS Seeker application is

designed Using Matlab Software. The snapshot of The Main Form GUI of this application is

shown in figure below.

Figure 19 : Main Form of QoS Seeker application

A brief usage of the QoS Seeker Main Form is as:

Choose GPS Type :

42

The user can choose between two types of tracking systems:

The first one is Geosense Location Sensor which is a third party software installed on

Windows 7 Laptops. This type is explained in section 4.2. The second type is GPS USB

Receiver. Its job is to locate four or more of The GPS satellites, figure out the distance to

each, and use this information to deduce the user location (Longitude and latitude). The

Global Positioning System GPS is actually a collection of 27 Earth-orbiting satellites.

Choose Map :

The user here can select between two Maps: El Mina and El Tal in Tripoli City. We have

chosen only these two places to test the application because we subscribed to the

WiMAX network of Cyberia Internet Provider which cover only these two areas in

Tripoli.

Refresh every :

In this selection, the user decides how much time he prefers that the application updates

his information like his location, the QoS Metrics , and the most important factor , the

map on which the VoIP call and the Video Streaming status are shown.

User Status :

The user has to define its status which is static or mobile. This selection is very important

because of the difference between the two status’ analysis methods of WiMAX QoS.

Application Type :

The user has to choose between 3 types of application:

2.4.1. VoIP Call

2.4.2. Multimedia covering Video Streaming on-demand and video conferencing .We did the

tests using only video on demand.

43

2.4.3. Other applications such as File Transfer.

Start Button :

When the user clicks on this button, the Map Form is launched. When this new GUI

opens, the QoS analysis begins for the first time. Then this Form refreshes to update the

information every time defined by the user in the Main Form (for example 1 minute).

Every time, the Map Form GUI is launched or refreshed the performance of QoS

parameters for WiMAX network such as, throughput, packet loss, average jitter and average

delay, are analyzed. The analysis is done in many steps explained in the next section. The figure

below shows the Map Form GUI at first launch for VoIP Call.

Figure 20 : VoIP Map Form The Map Form shows five parts of information. The following gives a brief usage of them:

Updating Information :

44

This part shows how much time the user wants the QoS Seeker to refresh and update the

Map and the other information. In addition, it shows the running steps while updating.

Your Location :

After reading the location of the user, the Latitude and the longitude are shown in this

part.

Network Infos :

This part shows the Bandwidth measured while calculating the QoS parameters and the

MOS and the status of VoIP Call.

Other Infos :

There is two buttons. “The Show Curves” button allows the user to see the curves of

measured and estimated Throughput, Jitter, Packet Loss and Latency. The “Other

Applications” button allows the user to test the QoS for other types of WiMAX services

such as file transfer.

The Map :

The map is updated every refresh time from the data loaded from the remote web server

database. Each MOS voice quality is represented by a color. The table below shows the

voice qualities and their colors depending on the MOS rate.

Rating Voice quality Color

5 Excellent Green

4 Good Blue

3 Fair Yellow

2 Poor Purple

1 Bad Red

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Table 5 : MOS colors representation

4.4. Analysis Steps of QoS Seeker

To analyze the quality of service in WiMAX network and illustrate the results to the user,

various steps are considered.

Getting the user Location using the GPS type selected by the user in the Main Form.

Measuring the Quality of Service parameters and calculating the VoIP MOS

Send the new values of QoS parameters to the save them in the database and Then

updating the Map after loading all data from the web server.

4.4.1. Getting the GPS Location

As mentioned before the QoS Seeker can determine the location of the user using one of two

GPS types. Each type has its own way in finding out the GPS coordinates (Latitude and

Longitude) of the user. The two types are The Geosense Sensor that uses the Windows 7 Sensor

and Location Platform and The GPS USB Receiver.

For the first type, the QoS Seeker uses a very simple approach to working with the Sensor

within the context of a C# Console application. The GeoCoordinateWatcher class that supplies

the location data that is based on latitude and longitude coordinates is applied. These coordinates

are saved in a txt file to use them after calculating the MOS to update the Map. This C#

application is developed because the Matlab is not compatible with Windows 7 Location

platform. The figure below shows the step” Getting the user GPS Location “.

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Figure 21 : Getting the user GPS Location Step

4.4.2. Measuring QoS parameters and Calculating MOS

This part discusses the parameters that influence on the quality of the speech (delay, packet

loss and jitter) and how speech quality is measured . Mean Opinion Score which is the subjective

method of measuring speech quality was discussed as well as objective methods like E-model is

described.

QOS Parameters

In order to measure the QoS parameters, we sent 100 ping packets of 160 bytes to the

host “www.skype.com”. The ping replies with the round Trip Time (RTT) which is the time

taken by the packet to arrive at its destination and returns back to its source. We used the values

of RTT to estimate the QoS factors.

http://www.skype.com/

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Latency or Average Delay

The main sources of delay are shown in the figure below :

Figure 22 : Latency in Network

Serialization Delay: It does not affect the overall delay. It is the amount of time that it takes to

place a bit or byte onto an interface.

Propagation Delay: It is the amount of time it takes a signal to propagate through the

propagation media such as a copper wire or a fiber optic. This delay might be unnoticeable, but

when united with other delays’ can produce a perceptible degradation to voice quality.

Handling Delay: it is also referred to Codec Processing delay. This delay is mainly caused by

the device that sends the packets on the network; it includes factors like packetization,

compression, queuing delay and packet switching. f

48

The Equation below show the calculation for Average Delay, where N is the number of

packets sent 𝑅𝑇𝑇 is the measured round trip time and (i) is the index of the RTT. We divided the

RTT by two because in calculating the available MOS we need only the one way delay.

𝑳𝒂𝒕𝒆𝒏𝒄𝒚 = Serialization delay + Processing delay + (𝑅𝑇𝑇𝑖

2)/𝑁

𝑁

𝑖=1

Jitter or Delay Variation

Jitter is commonly used as an indicator of consistency and stability of a network.

Measuring jitter is critical element to determining the performance of network and the QoS the

network offers. Latency is 1st order statistics (mean) of delay and Jitter is second order statistics

of delay (variance).

The Equation below show the calculation for Delay Variation, where N is the number of

packets sent 𝑅𝑇𝑇 is the measured round trip time and (i) is the index of the RTT.

𝑋𝑖 =𝑅𝑇𝑇𝑖

2

𝑱𝒊𝒕𝒕𝒆𝒓 = (𝑋𝑖 − 𝑙𝑎𝑡𝑒𝑛𝑐𝑦)2

𝑁 − 1

𝑁

𝑖=1

49

Packet Loss

Packet loss influences on the perceived quality of the application. Several reasons of

packet loss or corruption would be bit errors in the WiMAX network or insufficient buffers due

to network congestion when the channel becomes overloaded.

Packet loss calculation is relatively simple. The difference between the sum of all

packets that are sent and the sum of all packets that are received, gives the data that was lost. The

ratio of total data lost and the total data that was sent gives the packet loss.

A Matlab script was written calculate the QoS parameters. It is included in the appendix for

reference.

Mean Opinion Score (MOS)

E-model takes into account various factors that affect the speech quality and calculates a

Rating factor (R-factor) that ranges between 0 -100. The R-factor can also be converted into a

MOS rating to give the MOS score.

The equation of the R-factor is:

R-factor = R0 - Is - Id - Ie + A

Brief explanations of R-factor’s equation elements:

R0: is a base factor determined from noise levels, loudness etc.

Is : represents impairments occurring simultaneously with speech

Id: represents impairments that are delayed with respect to speech (e.g.

absolute delay, echo).

Ie: represents the so-called "equipment impairment factor”.

50

A: Advantage factor (A is 0 for wire line and A is 5 for wireless (into

building) and 10 for WiMAX).

Based on ITU G.107 recommendation, the R- factor equation can be simplified as:

R-factor = 93.2 – Id – Ie – A

The value of Ie, which is equipment impairment factor, is calculated as:

Ie = a + b ln (1+ c*PLoss/100)

Where, a, b and c are codec fitting parameters and PLoss is packet loss percentage.

The Codec fitting parameters for G.729 and G.711 are summarized in the table below.

Parameters G.711 G.729

Bitrates(kb/s)/frame size(ms) 64/20 8/10

A 0 11

b 30 31

c 15 15 Table 6 : Fitting Parameters for codec G.711 andG.729

The below summarizes the R-factor ratings and user satisfaction based on ratings

between 0 -100.

51

Figure 23 : R-factor rating with MOS score mapping and user satisfaction level

The ITU G.107 presents an equation to convert the R-factor value into MOS score.

𝒊𝒇 𝑹𝒇𝒂𝒄𝒕𝒐𝒓 < 0 ∶ 𝑴𝑶𝑺 = 𝟏

𝒊𝒇 𝑹𝒇𝒂𝒄𝒕𝒐𝒓 > 100 ∶ 𝑴𝑶𝑺 = 𝟒. 𝟓

𝒊𝒇 𝟎 < 𝑅𝑓𝑎𝑐𝑡𝑜𝑟 < 1000 ∶ 𝑴𝑶𝑺 = 𝟏 + 𝟎. 𝟎𝟑𝟓𝑹 + 𝟕. 𝟏𝟎−𝟔𝑹 𝑹 − 𝟔𝟎 (𝟏𝟎𝟎 − 𝑹)

With R=Rfactor

The value of Id, which is impairment due to delay is calculated as:

Id = 0.024d + 0.11 (d – 177.3) H (d – 177.3)

Where d is the total one way delay. It includes serialization delay, processing delay and

propagation delay in milliseconds. H(x) is a step function defined as:

H(x) = 0, x<0 and H(x) = 1 otherwise.

The figure below shows the step on QoS Seeker that Measure the QoS parameters and

estimating the MOS VoIP.

52

Figure 24 : Measuring QoS Parameters Step

4.4.3. Updating the Map

So far, the longitude and the latitude of the user are obtained, the QoS metrics are

measured and the MOS is calculated. These values are saved in a binary file called

“variables.mat “. In this step, each laptop has the QoS Seeker installed, periodically send the

new values of longitude, latitude and the QoS Metrics to a remote QoS server database. Within

the QoS map server all collected data is used to create the current QoS map over a large area of

El Mina and El Tal .Then this information is downloaded by any laptop requiring the QoS

Seeker information to update the Map on the graphical user interface.

In order to convert the GPS coordinates into XY pixels coordinates, we chose to use the

Mercator Map projection for plotting the points and the MOS status on the map.

53

WCF Service

WCF is a next-generation programming platform and runtime system for building,

configuring and deploying service-oriented applications. We created this service to save all

collected data from all users. There are two main functions in this service:

3. GetUserDetails (): this function retrieves all data in the database and sends it to the QoS

Seeker user.

4. InsertUserDetails (longitude, latitude, QoS Metrics): this function checks if the longitude

and latitude are existed before in the database. If yes, it updates the data existed with the new

values of QoS Metrics. If No, it inserts the data into the database.

In order to make sure that all data collected during the test are saved in one place and one

database, we hired a public IP Address to host the service. All users send by default the

data to this IP.

Mercator Map projection

To make the map seamless, and to ensure that aerial images from different sources line

up properly, we have to use a single projection for the two maps chosen El Mina and El Tal. We

chose to use the Mercator projection.

The Mercator projection has two important:

1. It’s a conformal projection, which means that it conserves the shape of small objects.

This is important when showing aerial imagery, because we want to avoid distorting the

shape of buildings. Square buildings should appear square, not rectangular.

2. It’s a cylindrical projection, which means that west and east are always straight left and

right and north and south are always straight up and down.

54

Figure 25 : El Mina Map

In order to simplify the calculations, we used the spherical form of this projection, not the

ellipsoidal form. We don’t need the extra precision of an ellipsoidal projection because the

projection is used only for map display, and not for displaying numeric coordinates. The

spherical projection causes approximately 0.33% scale distortion in the Y direction, which is not

visually noticeable.

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Pixel Coordinates

We have chosen the projection and scale to use; we can convert geographic coordinates into

pixel coordinates. Since the map width and height is different at each level, so are the pixel

coordinates.

Given the user latitude and longitude the pixel XY coordinates can be calculated as follows:

𝑿 = 𝒖𝒔𝒆𝒓𝑳𝒐𝒏𝒈𝒊𝒕𝒖𝒅𝒆− 𝑾𝒆𝒔𝒕𝑳𝒐𝒏𝒈𝒊𝒕𝒖𝒅𝒆 ∗ 𝟗𝟐𝟏

𝒎𝒂𝒑𝑳𝒐𝒏𝑫𝒆𝒍𝒕𝒂

And

𝒀 = 𝑴𝒂𝒑𝑯𝒆𝒊𝒈𝒉𝒕 − 𝑴𝒂𝒑𝑾𝒊𝒅𝒕𝒉𝑫𝒆𝒈

𝒁 − 𝒎𝒂𝒑𝑶𝒇𝒇𝒔𝒆𝒕𝒀

Where

𝒎𝒂𝒑𝑳𝒐𝒏𝑫𝒆𝒍𝒕𝒂 = 𝒆𝒂𝒔𝒕𝑳𝒐𝒏𝒈𝒊𝒕𝒖𝒅𝒆 − 𝒘𝒆𝒔𝒕𝑳𝒐𝒏𝒈𝒊𝒕𝒖𝒅𝒆

And

𝒁 = 𝟐 ∗ 𝒍𝒐𝒈(𝟏 + 𝒔𝒊𝒏 𝑼𝒔𝒆𝒓𝑳𝒂𝒕𝒊𝒕𝒖𝒅𝒆

𝟏 − 𝒔𝒊𝒏 𝑼𝒔𝒆𝒓𝑳𝒂𝒕𝒊𝒕𝒖𝒅𝒆 )

And

𝑴𝒂𝒑𝑾𝒊𝒅𝒕𝒉𝑫𝒆𝑮 =

𝑴𝒂𝒑𝒘𝒊𝒅𝒕𝒉𝒎𝒂𝒑𝑳𝒐𝒏𝑫𝒆𝒍𝒕𝒂

∗ 𝟑𝟔𝟎

𝟐 ∗ 𝒑𝒊

And

𝒎𝒂𝒑𝑶𝒇𝒇𝒔𝒆𝒕𝒀 = (𝒎𝒂𝒑𝑾𝒊𝒅𝒕𝒉𝑫𝒆𝒈

𝟐 ∗ 𝒍𝒐𝒈 𝟏 + 𝒔𝒊𝒏(𝒎𝒂𝒑𝑳𝒂𝒕𝑩𝒐𝒕𝒕𝒐𝒎𝑫𝒆𝒈𝒓𝒆𝒆 𝟏 − 𝒔𝒊𝒏 𝒎𝒂𝒑𝑳𝒂𝒕𝑩𝒐𝒕𝒕𝒐𝒎𝑫𝒆𝒈𝒓𝒆𝒆

)

56

And

𝒎𝒂𝒑𝑳𝒂𝒕𝑩𝒐𝒕𝒕𝒐𝒎𝑫𝒆𝒈𝒓𝒆𝒆 = 𝒔𝒐𝒖𝒕𝒉𝑳𝒂𝒕𝒊𝒕𝒖𝒅𝒆 ∗𝒑𝒊

𝟏𝟖𝟎

With

4.1. EastLongitude: is the East Longitude of the Map.

4.2. WestLongitude: is the West Longitude of the Map.

4.3. SouthLatitude: is the south Latitude of the Map.

The figure below shows the step on QoS Seeker when updating the map:

Figure 26 : Updated Map

57

Chapter 5

Implementation results

To analyze the quality of service in WiMAX network, various real life use cases are

considered. WiMAX affords basic IP connectivity. VOIP is the first application tested. With the

availability of a larger data channels, another familiar application these days is viewing videos

over the internet. So video streaming is analyzed as well. In this chapter, the implementation

results are presented. The QoS parameters obtained for VOIP traffic is presented first. The video

streaming traffic results follow.

5.1. Test for Static WiMAX user

We test the QoS Seeker from many places in El Mina. The time is every one minute for

20 minutes of testing.

5.1.1. Results for VOIP traffic using G.711 codec

In the first case the VOIP traffic is tested with codec G.711. Figure 30 to Figure 35 displays

the variation of throughput, percentage packet loss, average jitter, and average delay measured

along with the QoS Seeker for 20 min and the calculated MOS values.

A. Bandwidth Availability

This table shows the Bandwidth tests in Kb/s for 20 min during VoIP Call.

58

Time

(min)

Download

(Kbps)

Upload

(Kbps)

Time

(min)

Download

(Kbps)

Upload

(Kbps)

1 4 40 11 72 8

2 70 20 12 72 24

3 78 36 13 92 36

4 90 8 14 82 36

5 68 30 15 86 34

6 74 6 16 74 18

7 86 14 17 64 38

8 94 42 18 82 18

9 110 10 19 114 60

10 76 56 20 94 8 Table 7 : Download and Upload rates for VoIP

Figure 27 : VoIP Download rates Plot

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Figure 28 : VoIP Upload Rates Plot

The maximum bandwidth available was 114Kb/s and the minimum was 4kb/s. the

average is around 79 Kb/s. the maximum value is obviously a very good measure for VoIP

deployment. If we ignore it, the minimum value is not enough to guarantee a good VoIP

implementation. Although the bandwidth requirement is not the most important issue in ensuring

a good QoS in VoIP application , the greater the connection speed does imply the better voice

quality that we can get.

B. Jitter Performance

The figure below shows the jitter values obtained during 20 minutes of measurements.

These values are measured for a period of 1 min in each VoIP session. The minimum value was

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around 10 ms at time t=9 minute while the maximum value was around 110 ms at time t =2 min.

the measurements were fluctuated quite obviously.

Figure 29 : VoIP Measured Jitter

We can divide the standard of good jitter level into four categories:

- 0-30ms: Excellent

- 30-40ms : Very good

- 40-50ms : Good

- 50-60 ms : Fair

- Otherwise : Poor

Jitter is an issue that only occurred in packet-based network and cannot be avoided. It

happens because the packets that are sent one by one arrive out of sequence and time because of

travelling. The jitter will get worst in a congested network. To deal with this problem and to

minimize the value of jitter itself, a network with uncongested network and high bandwidth

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availability is definitely most desirable. In this test we can see that the bandwidth availability for

WiMAX network is sometimes good and other times is not.

Generally, a direct correlation between bandwidth and jitter recommended that the highest

bandwidth available should generate the smallest jitter value. However, this is test showed that it

was not necessarily happened like that. For example the jitter value 110 ms was the biggest at

t=2 min but the bandwidth measured on that time was not the lowest, measured 70 Kb/s. Like so,

the smallest jitter was 10 ms at t=9 min but the bandwidth measured was 110 Kb/s, which is not

the Highest measured value.

All of these results showed that the QoS elements of bandwidth for this network did not

really affect the jitter occurred during the VoIP call.

C. Latency Performance

The ITU-T recommendation for a good quality voice is for the latency to be less than 150

ms. the figure below shows the latency measured during the test of the QoS Seeker.

Figure 30 : VoIP Measured Latency

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According to the Standard Quality Management (SQM) scale, we can divide the latency into:

- 0-50ms : good

- 50-300ms : acceptable

- from Otherwise : poor

From the figure above, the biggest latency value was 290 ms at t=14 min while the smallest

latency was 140 ms at t= 1min, averaging for this network around 213 ms. Comparing these

latency with the Standard Quality Management scale , we can see that these levels of latency

were good.

D. Packet Loss Performance

Figure 31 : VoIP Measured Packet Loss

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We can see that the packet loss values varied between 5% and 34% during the 20 min of

video call. This of course affects the voice quality status which differs between poor, good, and

very good quality. When the packet loss is high the voice was not completely clear.

E. Overall VoIP performance (MOS value)

The overall performance of this VoIP Call or of VoIP in general can be evaluated using Mean

Opinion Score (MOS) values. The calculated MOS values are stated in the figure below.

Figure 32 : MOS values Plot

These values are calculated using the equations mentioned in section 4.4.2. The values

varied between 3.5 and 4.4, averaging around 3.94. According to Figure 26 and table, these

values are rated as just perceptible but not annoying. From this result we can conclude that

although the latency and jitter measured were good some time, there are other factor that

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contribute to the all performance of VoIP in a network which is the packet loss. These factors

have to be as loss as possible in order to set a good quality of VoIP Service.

5.1.2. Results for Video Streaming

There are several proposed video quality factors that affects quality of video streaming.

The Video Quality Metric (VQM) is a very important factor that has been accepted as ANSI

standard T1.801.03. VQM is based on comparison of the original and degraded video. We did

not use it because of its high computational complexity and requirement for high-end hardware,

as well as communication overhead.

For video streaming, the bandwidth and the jitter play important roles in the quality of

video. The average delay is not very important, because users tolerate some startup delay.

Bandwidth is the main factor influencing whether a video of the desired quality. As video frames

are transmitted in packets over the network, lost or delayed packets may cause frame drops at the

user. Low jitter is a requirement for a smooth streaming experience. Inter-frame jitter is easily

perceptible by the user.

While testing the video streaming performance, we played a video on you tube.com with

35 min of length and we run the QoS Seeker application. WiMAX supports both live and on-

demand streaming. In this Project, we focus only on on-demand streaming.

Figure 36 to Figure 40 displays the variation of throughput, percentage packet loss, average

jitter, and average delay measured along with the QoS Seeker for 20 min.



65

Time

(min)

Download

(Kbps)

Upload

(Kbps)

Time

(min)

Download

(Kbps)

Upload

(Kbps)

1 71 6 11 68 7

2 62 8 12 79 7

3 102 7 13 69 6

4 68 6 14 69 6

5 70 5 15 70 9

6 31 6 16 78 6

7 62 5 17 66 6

8 52 7 18 70 6

9 75 12 19 84 7

10 56 6 20 71 6

Table 8 : Video Streaming Downloads and Uploads rates

Figure 33 : Video Streaming Downloads rates Plot

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Figure 34 : Video Streaming Uploads rates Plot

Ignoring the maximum value of bandwidth 102 kbps that is obviously a good measure for

video streaming deployment, the minimum value alone is not good enough to guarantee a good

quality but the average bandwidth which is around 69 kbps still a good measured value to deliver

a good video streaming. The Streaming-Video is typically unidirectional that means that the

upload link is not used. Therefore the upload has low values.

Since the bandwidth requirement is the most important issue in ensuring a good QoS in

video streaming, the greater the connection speed does imply the better quality that we can get.

Our experience talking over during the test showed that we were able to have a smooth video

which noticeable interruptions only in the first 4 minutes.

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The figure shows the jitter values obtained during 20 minutes of measurements. These

values are measured for a period of 1 min . The minimum value was around 15 ms at time t=14

minute while the maximum value was around 187 ms at time t =10 min.

Figure 35 : Measured Jitter Video Streaming

We adopt the evaluation method of Wang et al. in our study. It proposes a simple quality

classification based on jitter, wherein smooth video has jitter less than 50 ms, rough video has

jitter exceeding 300 ms, and average video has jitter between these two thresholds.

According to this evaluation we can see that the jitter doesn’t exceed the maximum

thresholds which mean that the video streaming was good during the test. we remark that the

jitter value increases with time then it increases after 10 minutes of playing . Then it becomes a

constant value because the video was full buffering.

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Depending on the video application's buffering capabilities, the Latency in video

streaming should be no more than 4 to 5 seconds. the figure below shows the latency measured

during the test of the QoS Seeker.

Figure 36 : Measured Latency Video Streaming

From the figure above, the biggest latency value was 266 ms at t=10 min while the

smallest latency was 64 ms at t= 1min, averaging for this network around 157 ms. Comparing

these latency with the evaluation, we can see that these levels of latency were excellent. The

video suffered frequent stutters and pauses during the first 6 min but then no pauses happened .

these is because the variation of latency values.

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When addressing the QoS needs of Streaming-Video traffic, the Loss should be no more

than 5 percent.

Figure 37 : Packet Loss Video Streaming

Video and audio quality are directly affected by packet loss, since the video streaming

deployment uses multicast over UDP (vs. RTP), which provides no protection from packet loss.

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5.2. Test for Mobile WiMAX User

To analyze the quality of service in mobile WiMAX network, we tested the VoIP

application. The user drove with speed 10km/h that reaches 50 km/h with time .The problem of

mobility is important in wireless network because internet connectivity can only be useful if it’s

available during the movement of node. To enhance mobility, wireless access systems are

designed such as IEEE 802.16e to operate on the move without any interruption of services. In

this section we are analyzing the QoS parameters Throughput, Average Jitter and Average end to

end Delay of a mobile WiMAX network (IEEE 802.16e).

5.2.1. Results for VOIP traffic using G.711 codec

the VOIP traffic is tested with codec G.711. Figure 41 to Figure 46 displays the variation of

throughput, percentage packet loss, average jitter, and average delay measured along with the

QoS Seeker for 5 minutes and the calculated MOS values.



Time

(sec)

Download

(Kbps)

Upload

(Kbps)

30 82 13

60 63 17

90 66 20

120 54 12

150 62 23

180 45 18

210 35 16

240 32 8

270 29 10

300 33 14

Table 9 : Mobile Downloads and Uploads rates

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Figure 38 : mobile download rates plot

Figure 39 : mobile Upload rates plot

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The throughput is varying according to data or packets received and sent by the VoIP application The

variation of throughput with respect to change in speed is shown in the figure 41. The speed is

increasing with time. According to figure 41, at t=30s the speed was 10 km/h (Kilometer per hour)

the throughput was 82 kbps, with the increase in speed the throughput is decreasing. At speed of

50Km/h the throughput is minimum i.e. 29 kbps. As the user moves, it will perform handover and

will go far away from its original registered BS and during that time there is loss of data (bytes and

packets). After that as speed increases the throughput will start increasing again .


Figure 40 : Measured mobile Jitter

According to figure 43, jitter is very less initially i.e.200 ms when the user is moving with less

speed of 10km/h; with increase in speed, jitter will also increase i.e. 630ms at 50 Km/h speed.

The reason is that data is split up into manageable packets with headers and footers that specify

the correct order of the data packets or whole signal is broken down into portions of data which

73

is transmitted to the receiving unit of El Mina Base station for assembly. If jitter occurs,

synchronization becomes a problem and the receiving unit finds it difficult to correctly assemble

the incoming data stream. Therefore at high speed jitter is more and throughput is less.


The ITU-T recommendation for a good quality voice is for the latency to be less than 150

ms. During transmission, delay is introduced and average end to end delay (Latency) changes

with the change in speed. Variation of Latency with respect to speed in time is shown in figure

44.

Figure 41 : Measured mobile Latency

According to the figure, the average delay is less when speed is less i.e. 280 ms at the

speed of 10 km/h but as speed increases average delay decreases i.e. 712 ms at the speed of 50

km/h. the Average delay increases or decreases according to movement of the user .

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Figure 42 : Measured mobile Packet Loss

As the user moves, the speed increases and the packet loss percentage increases rapidly

i.e. 20% loss at the speed of 10 km/h but as speed increases, loss increases too i.e. 88% loss at

the speed of 45 km/h. In addition a handover problem may occur and during that time there is

loss of data (bytes and packets).

E. Overall VoIP performance (MOS value)

The overall performance of this VoIP Call or of VoIP in general can be evaluated using Mean

Opinion Score (MOS) values. The calculated MOS values are stated in the figure below.

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Figure 43 : mobile MOS values

These values are calculated using the equations mentioned in section 4.4.2. The values

varied between 1.2 and 3.7, averaging around 2.3. According to Figure 46 and table 4, these

values are rated as just Perceptible & slightly annoying and Annoying but not objectionable.

From this result we can conclude that the latency and jitter measured were not good enough to

VoIP call , and the other factor that contribute to the all performance of VoIP in a network which

is the packet loss is very high . These factors have to be as loss as possible in order to set a good

quality of VoIP Service but in this case they are not. These causes a poor VoIP call.

76

Chapter 6

Conclusion and Future Work

6.1. Conclusion

In the Project, we developed an application that evaluates the performance of the network

by analyzing the Quality of Service metrics. This application is called “WiMAX Quality of

Service Seeker “or “WiMAX QoS Seeker”. It can provide the user the ability to easily determine

the location of high quality WiMAX connections. The applications QoS Seeker targets are real

time services such as video streaming and Voice over IP.

To achieve its goals the QoS Seeker analyzes the parameters at the end user that may affect the

quality of the service desired. VoIP traffic and video streaming traffic was analyzed using a

simulation based on Matlab Software. The effect of QoS parameters like throughput, packet

loss, average jitter and average delay was studied.

For Fixed WiMAX user, the application works well and he no longer has to guess and/or

randomly move to find a physical position where an applications’ QoS is at an acceptable level.

But here the results of the analysis are not optimal because of the few number of packets sent to

measure the Round Trip Time (RTT).

While for mobile WiMAX user, the application can’t show the best quality of service

results. The speed of the mobile user and his location are the most issues that lead us to wrong

results. For example, A handover may occur while the user is moving which results a bug in the

analysis.

77

For the real time simulation, the user should be in El Mina or El Tal where the WiMAX network

covers these two areas .Otherwise it will not work properly.

The IEEE 802.16/WiMAX network architecture was presented and the MAC layer

features that enable end-to-end QoS mechanism in the network were discussed. The general

concepts of Quality of service (QoS) in WiMAX network were studied. Various service flows

that are supported in WiMAX were discussed in details. Related survey was presented in detail

to provide background to the reader.

6.2. Future Work

VOIP traffic and video streaming were the two applications considered in the current

analysis. Further analysis could be done for other applications including, video telephony which

combines video traffic and VOIP traffic, File Transfer Protocol (FTP) traffic etc.

The work showed in this report builds a MOS score calculator based on E-Model method.

This calculator reads the delay and packet loss measured by capturing the RTT of 100 packets.

Possible future work could be integrating the new objective approach with a packet capture tool

like Wireshark to calculate the speech quality during real time packet capture. This would help to

efficiently monitor the speech quality of a live call in real time. This can result in designing an

effective algorithm to reduce the handover latency in VoIP.

For mobile WiMAX user , the possible future work could be using a new algorithm that

can integrate the speed of the user and the other factors which may affects the quality of service

of the real time applications.

78

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Appendix A1

Equipments used

iFLY WiMAX USB Dongle

“Stylish, compact USB modem that work with any laptop or desktop

with a USB port and of course fits the pocket while on the move.

Based on the latest WiMAX technologies, iFLY is the first of its

kind in Lebanon . It is a portable High Speed Internet service that

offers you a great Wireless Internet experience both at home and on

the move (Anywhere with iFLY coverage)

In addition to being portable and cable free, iFLY is very easy to install”

Globalsat USB GPS Receiver

“Globalsat USB GPS receivers allow for real-time street navigation by using your laptop for

graphical plotting and positioning of your route. Simply load the GPS driver, plug the GPS

receiver into your computer’s USB port and install your own personal mapping software to begin

to view your position in real-time in relation to the surrounding streets in your travel area. “