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8/8/2019 INDOOR PROPAGATION PREDICTION AND MEASUREMENTS WITHIN MULTISTORY BUILDING FOR WIRELESS LAN APPLIC

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INDOOR PROPAGATION PREDICTION AND MEASUREMENTS WITHINMULTISTORY BUILDING FOR WIRELESS LAN APPLICATIONS

ABDUSAMEA I.A OMER

UNIVERSITI TEKNOLOGI MALAYSIA


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PSZ 19:16 (Pind. 1/97)

UNIVERSITI TEKNOLOGI MALAYSIA

BORANG PENGESAHAN STATUS TESIS

INDOOR PROPAGATION PREDICTION ANDJUDUL:

MEASUREMENTS WITHIN MULTISTORY BUILDING

FOR WIRELESS LAN APPLICATIONS

SESI PENGAJIAN: 2006 / 2007

Saya ABDUSAMEA I.A OMER

mengaku membenarkan tesis (PSM/ Sarjana/ Doktor Falsafah)* ini disimpan di PerpustakaanUniversiti Teknologi Malaysia dengan syarat-syarat kegunaan seperti berikut:

1. Tesis adalah hakmilik Universiti Teknologi Malaysia.2. Perpustakaan Universiti Teknologi Malaysia dibenarkan membuat salinan untuk tujuan

pengajian sahaja.3. Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran antara

institusi pengajian tinggi.4. **Sila tandakan ()

SULIT(Mengandungi maklumat yang berdarjah keselamatan ataukepentingan Malaysia seperti yang termaktub di dalamAKTA RAHSIA RASMI 1972)

TERHAD(Mengandungi maklumat TERHAD yang telah ditentukanoleh organisasi/ badan di mana penyelidikan dijalankan)

TIDAK TERHAD

Disahkan oleh

(TANDATANGAN PENULIS) (TANDATANGAN PENYELIA)

Alamat Tetap:408 S47 KTC UTM

SKUDAI JOHOR MALAYSIA

PROF. DR. THAREK BIN ABD. RAHMAN

81310 Nama Penyelia

11 MAY 2007 11 MAY 2007Tarikh: Tarikh:

CATATAN: * Potong yang tidak berkenaan.** Jika tesis ini SULIT atau TERHAD, sila lampirkan surat daripada pihak

berkuasa/ organisasi berkenaan dengan menyatakan sekali sebab dan tempohtesis ini perlu dikelaskan sebagai SULIT atau TERHAD.

Tesis dimaksudkan sebagai tesis bagi Ijazah Doktor Falsafah dan Sarjanasecara penyelidikan, atau disertasi bagi pengajian secara kerja kursus danpenyelidikan, atau Laporan Projek Sarjana Muda (PSM).


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I hereby declare that I have read this project report and in my opinion this project

report is sufficient in terms of scope and quality for the award of the degree of

Master of Engineering(Electrical-Electronics & Telecommunication)

Signature :..

Supervisor : PROF DR.THAREK BIN ABDUL RAHMAN

Date : 11 May 2007


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INDOOR PROPAGATION PREDICTION AND MEASUREMENTS WITHIN

MULTISTOY BUILDING FOR WIRELESS LAN APPLICATIONS

ABDUSAMEA I.A OMER

A project report submitted in partial fulfilment of the

requirements for the award of the degree of

Master of Engineering (Electrical-Electronics & Telecommunication)

Faculty of Electrical Engineering

Universiti Teknologi Malaysia

MAY 2007


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ii

I declare that this project report entitled Indoor propagation prediction and

measurements within multistory building for wireless LAN applications is the result

of my own research except as cited in the references. The project report has not been

accepted for any degree and is not concurrently submitted in candidature of any other

degree.

Signature :

Name : ABDUSAMEA I.A OMER

Date : 11 MAY 2007


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iii

To

My Beloved Parents , Brothers and Sisters


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iv

ACKNOWLEDGMENT

In the name of Allah, Most Gracious, and Most Merciful

Praise be to Almighty Allah (Subhanahu Wa Taala) who gave me the

courage and patience to carry out this work. Pease and blessing of Allah be upon his

last prophet Mohammed (Sallulaho-Alaihe Wassalam) and all his companions

(Sahaba), (Razi-Allaho-Anhum) who devoted their lives towards the prosperity and

spread of Islam.

My deep appreciation and heartfelt gratitude goes to my supervisor,

PROF.DR THAREK BIN ABDUL RAHMAN for his kindness, constant endeavor,

and guidance and the numerous moments of attention he devoted through out thiswork.

I extend my deepest gratitude to my close friend, Eng. Ibrahim Abuharba for

his encouragement and motivation. Also I would like to thank friends and stuff in

wireless communication center (WCC) for their help facilities and for providing

conductive working environment

Family support plays a vital role in the success of any individual. I would like

to convey a heartfelt thanks to my parents, brothers, and other family members

including all my uncles, ants and their families; their prayers and encouragement

always helped me take the right step in life.

A heartfelt gratitude and acknowledgement are due to the Libyan community

in UTM, Skudai for their kindness, care, valuable advices and cooperation, which

generates a similar environment as what I left.


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v

ABSTRACT

In recent years, the possibility of using radio for data and voice

communications inside the buildings has become an attractive proposition. A

prerequisite to the design of indoor radio communication systems is knowledge of

indoor propagation characteristics. These characteristics can be used to determine theoptimum location of the base station antenna for a desired coverage within a

building. Propagation prediction within buildings is made difficult by the occurrence

of various propagation phenomena which depend on specific building structures. In

this project the investigation for WLAN system is done for three different buildings

inside University of Technology Malaysia. The Site Ware Technology's site specific

propagation prediction tool is a three-dimensional (3-D) ray tracing code employing

modified shoot and bounce ray(SBR) method know as the Vertical Plane Launch

(VPL) will be used to predict indoor propagation effects with different building

structures to show the prediction of the path loss and the time delay spread for

WLAN system inside these buildings, also a comparison between the real time

measurements using AirMagnet software and the prediction using VPL software

has been done for verification and the AutoCAD tool with the help of Ms Excel, was

used to measure all the building's dimensions for highly accurate building database.

The results from both prediction and measurement are in form of numbers, so Matlab

has been used to present these outputs in 2D display. Finally, based on the evaluation

results, we provide a set of recommendations that might help to improve this work

and fulfill the indoor user requirements.


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vi

ABSTRAK

Syak kebelakangan ini , penggunaan radio untuk komunikasi data dan suara

dalam bangunan telah menjadi suatu proposisi yang menarik . factor yang diperlukan

dalam rekaan sistem komunikasi radio dalaman adalah pengetahuan tentang karakter-

karakter perambatan dalaman . karakter- karakter ini boleh digunakan dalam

penentuan lokasi optima antena stesen asas bagi sesuatu , rangkuman dalam

bangunan yang diinginkan ramalan perambatan dalam bangunan menjadi sukar

dengan kejadian pelhagi fenomena perambatan yang bergantung kepda struktu

struktu spesifik bangunuan . dalam projek ini ,siasatan sistem WLAN dilaksanakan

untuk tiga bangunan yang berbeza dalam Universiti Teknologi Malaysia . alat

ramalan perambatan lokasi spesifik oleh site ware technology ialah tiga dimensi

(3D)ray tracing kod yang menggunakam modifikasi shoot dan bounce ray(SBR) cara yang juga dikenali sebagai Vertical Plane Launch (VPL). la akan

digunakan dalam meramal efek-efek perambatan dalaman dengan pelbagai Stnrkuer

beugunan berbeza whtuk menunjukkan ramalan path loss dan time delay opread

bagi sistem WLAN dalam bengunan serta perbandingan antara pengukuran sebener

menggunalcan software dilaksanakan untuk tujuan verifikasi. Dengan bantuan Ms

Excel, alat antocad digunakam untuk mengukur samua dimensi bengunan untuk

memperoleh dadbase bangunan yang dalam bentuk numbor-nombor. Oleh itu,

Matlab digunakan untuk menunjuklcan output-output ini dalam pameran secara 2D.

Akhir sekali dengan berpandutcan hasil-hasil evausasi, satu set cadangan membina

dalam meningkatkan kerja ini dan mencapai kehendak-kehendak pengguna dalaman

akan dibekalkan.


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TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENTS ivABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES xi

LIST OF FIGURES xii

LIST OF SYMBOLS xv

LIST OF APPENDENCES xvii

1 INTRODUCTION 1

1.1 Overview 11.2 Problem Statement 2

1.3 Objective of the Project 21.4 Scope of the Project 2

1.5 Methodology of the Project 3

1.5.1 Site Survey 3

1.5.2 Data Collection of Multistory buildingusing AutoCAD

3

1.5.3 Excel Files 3

1.5.4 VPL Simulation 3

1.5.5 Real time measurement 4

1.6 Organization of the Thesis 6

2 LITERATURE REVIEW 7


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2.1 Wireless Local Area Network (WLAN) 7

2.1.1 Introduction 7

2.1.2 Benefits of Wireless LANs 7

2.1.3 Architecture of a Wireless LAN 8

2.1.3.1 Stations 8

2.1.3.2 Access Points (APs) 8

2.1.3.3 Wireless Clients 9

2.1.3.4 Basic Service Set 9

2.1.3.5 Independent Basic Service

Set 9

2.1.3.6 Infrastructure Basic Service

Set9

2.1.3.7 Extended Service Set 10

2.1.3.8 Distribution System 10

2.2 IEEE 802.11 Standards 10

2.3 Indoor Radio Wave Propagation 12

2.3.1 Reflection: 13

2.3.2 Diffraction: 142.3.3 Refraction 152.3.4 Scattering 15

2.3.5 Indoor Path Loss 16

2.3.6 Free Space Los 16

2.3.7 Line of Site Path Loss 18

2.3.8 Obstructed Path Loss 192.3.9 Doppler frequency shift 20

2.3.10 Multipath and Fading Effects 22

2.3.11 Delay Spread 24

2.3.12 Raleigh Fading 252.3.13 Rician Fading 25

2.3.14 Related work 26

3 RAY TRACING SOFTWARE AND 30


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5.1 Conclusion 635.2 Future Work

64

REFERENCES 65

Appendices A - F 67-167


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xi

LIST OF TABLES

TABLE NO. TITLE PAGE

2.1 WLAN standards 12

2.2 2.4 GHz Signal Attenuation 20

2.3 Diffierent Between two types of ray tracing models 29

3.1 Part of WCC building database 363.2 Example of the receivers database 37

3.3 Interior building database 39

3.4 Simulation Command input 40


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xii

LIST OF FIGURES

FIGURE NO. TITLE PAGE

1.1 AirMagnet Software with Laptop 4

1.2 Flow chart of the methodology 5

2.1 Access Point infrastructure 8

2.2 Wireless Local Area Network Architecture using anInfrastructure BSS

10

2.3a Reflected Signal on partial reflective surface 13

2.3b Reflected Signal on perfect reflective surface 13

2.4 Diffraction of a Signal 14

2.5 Refracted wave 15

2.6 Scattered Wave front on an I-beam 16

2.7 Free Space Radiating Point Source 17

2.8 2.4GHz Typical Path Loss 18

2.9 Multiple Floors Indoor Path Loss 19

2.10 Doppler frequency shift effect 22

2.11 Multipath signal in indoor environment 22

2.12 Small Scale Fading 24

2.13 Impulse response and frequency transfer function of a

multipath channel.24

2.14 Measurement system by Symbol 26

2.15 Signal level without pepole 27

2.16 Signal level with present pepole 27

2.17 Effect opening and closing the door 28

3.1 Two-Ray Model 31

3.2 Ray generation in horizontal plane (Liang and Bertoni

1998)33

3.3 Flow chart of ray-tracing simulation based on the VPL 34


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method (Liang and Bertoni 1998)

3.4 Sample of the AUTOCAD Building map of WCC 36

3.5 AutoCAD Receiver location map 37

3.6 Command input simulation 41

4.1 Example of power and delay spread output 44

4.2 Example of impulse response output 45

4.3 Example of ray path information output 46

4.4 Example of AirMagnet measurement (Kolej Perdana) 47

4.5 Simulation Path Loss for Mobile Lab room (WCC) 48

4.6 Time delay spread for Mobile Lab room (WCC) 49

4.7 Simulation Propagation predictions Path Loss for

(WCC) 49

4.8 Time delay spread for WCC 50

4.9 Kolej Perdana First floor Path loss propagation

predication at 2400MHz Carrier Frequency 50

4.10 Kolej Perdana Second floor Path loss propagation


4.11 Kolej Perdana Third floor Path loss propagation


4.12 Kolej Perdana Forth floor Path loss propagation


4.13 Kolej Perdana Fifth floor Path loss propagation


4.14 Kolej Perdana Sixth Floor Path loss propagation


4.15 Kolej Perdana Seventh Floor Path loss propagation


4.16 Kolej Perdana All the seven Floors Path loss

propagation predication at 2400MHz Carrier Frequency 54

4.17 Kolej Perdana-One Floor Path loss propagation

predication at 2400MHz Carrier Frequency (Based on

assumption that the building is only one floor) 54

4.18 Kolej Perdana One Floor Path losses Comparison 55


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between 1 ray (blue) model and 2 ray model (red)

propagation predication at 2400MHz Carrier Frequency

4.19 Time delay spread for the First Floor Kolej Perdana 55

4.20 Time delay spread for the Second Floor Kolej Perdana 56

4.21 Time delay spread for the Third Floor Kolej Perdana 56

4.22 Time delay spread for the Fourth Floor Kolej Perdana 57

4.23 Time delay spread for the Fifth Floor Kolej Perdana 57

4.24 Time delay spread for the Sixth Floor Kolej Perdana 58

4.25 Time delay spread for the Seventh Floor Kolej Perdana 58

4.26 Time delay spread for All the Seven Floors Kolej

Perdana 59

4.27 Kolej 11 All the four Floors Path loss propagation


4.28 Time delay spread for all the four Floors Kolej 11 MA7 60

4.29 comparison between real-time measurements and

simulation for Kolej Perdana 61


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xv

LIST OF SYMBOLS

WLAN - wireless local area networks

WCC - Wireless Communications Center

IEEE - Institute of Electrical and Electronic Engineering

ETSI - European Telecommunications Standards Institute

VPL - Vertical Plane Launch

Wi-Fi - Wireless Fidelity

LOS - Line of sight

OFDM - Orthogonal frequency division multiplexing

DSSS - Direct sequence spread spectrum

Pt - Transmitting power

Pr - Receiving power

Gt - Transmitter antenna gain

Gr - Receiver antenna gain

Ar - Effective aperture of antenna

- Wavelength

C - Velocity of light

dB - Decibels

- Incidence angle

f - Frequency

ht - High of receiver antenna

hr - High of transmitter antenna

A - Attenuation factor

- Ground reflection coefficient

r1, r2 - Phase path distance along

h - Fresnel zone radius to the knife edge

o - Free space wavelength


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d - Distance difference

1d - Distance from transmitter to obstacle

2d - Distance from transmitter to obstacle

- Delay spread

v - Speed of portable

fc - Carrier frequency

L - Path loss

L0 - Reference loss

Li - Floor loss factor

D - Distance

h(t) - Impulse response

nA - Amplitude of signal

n - Arrival time

n - Arrival phase

iE - Received field amplitude

oE - Transmitting field strength


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xvii

LIST OF APPENDICES

APPENDIX TITLE PAGE

A WIRELESS COMMUNICATION CENTER

SIMULATION DATABASES67

B KOLEJ PERDANA SIMULATION DATABASES 76

C KOLEJ 11 MA7 BUILDING SIMULATION

DATABASES 91D RAY TRACING PROPAGATION PREDICTION 104

E AIR MAGNET SOFTWARE

F AUTOCAD IMPLEMINTATION 130


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CHAPTER 1

INTRODUCTION

1.1 Overview

The past decade has witnessed a phenomenal growth in wireless

communication. Indoor wireless communication - such as is associated with personal

communication (PCS) and wireless local- area networks (LANs) - is exploding

rapidly. The need for an efficient way to evaluate radio propagation in buildings is

increasing. It is also critical to optimize the locations of the base stations required toensure satisfactory system performance. Consequently, radio-propagation prediction

for indoor environments, which forms the basis for optimizing the location of the

base stations, has become an important research topic.

Indoor radio propagation is not influenced by weather conditions, such as

rain, snow, or clouds, as is outdoor propagation, but it can be affected by the layout

in a building, and especially by the use of different building materials. Owing to thereflection, refraction, and diffraction of radio waves by objects such as walls,

windows, doors, and furniture inside the building, the transmitted signal often

reaches the receiver through more than one path, resulting in a phenomenon known

as multipath fading [1].


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1.2 Problem Statement

Wireless LAN have become widely spread over the last few years, it has been

one of the most significant research topics to investigate how radio waves propagate

inside office environments, since local objects like pillars, walls, doors and windows

may reduce the link performance of such low power systems.

The existing for indoor environments is that the signal propagated from the

transmitter antenna will experience many different signal transformations and paths

with a small portion reaching the receiver antenna. Awareness of this process will

assist the user to better understand radio performance limitations.

1.3Objective

This project is aiming to predict and measure the signal strength of wireless

LAN in a multi storey building (Kolej Perdana) in the University Of Technology

Malaysia in order to Obtain best efficiency and coverage of indoor propagation for

wireless LAN systems.

1.4 Scope of project

To provide proper study of wireless LAN propagation signal in multi storey

building, in which the signals are traced , and to build the database of a multi storey

building by using AUTOCAD and MS EXCEL Software; the simulation results will

be Presented by using MATLAB software for visualizing; The prediction will be

done at a carrier frequency 2.4GHz (based on IEEE 802.11 b/g standards) the

simulated result will be compared with the real time measurements that obtained

using Air magnet software In order to Analyze the simulated result.


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1.5 Project Methodology

1.5.1 Site Survey

Site survey involved in locating the place to be measured. As initial stage of

this project Wireless Communication Center (WCC) in Universiti Teknologi

Malaysia was the first place to be tested.

In the second stage of this project (kolej perdana) will be our target in the

following sections the procedures that have been taken in order provide a good

evaluation of coverage are introduced.

1.5.2 Data Collection of Multistory building

Building data base was provided by WCC as DWG file (DraWinG) witch

will be imported to CAD so all the measurements of the building dimensions can be

obtained easily.

1.5.3 Excel Files

Upon having the dimensions of the multistory building with the help of

AUTOCAD the dimensions are entered into an excel file , after words a file.txt can

be generated to be imported to VPL .

1.5.4 VPL Simulation

Firstly selecting up the parameters for VPL such as increment angel betweensuccessive rays, operating frequency (in our case 2.4 GHZ), fresnel zone width first


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and second zone, antenna type (in our case monopole) Secondly, simulation is

carried out and the outcome of the simulation is tested If no errors, the results can be

plotted by using MATLAB two of the most graphs that will be plotted are path loss

and time delay spread .

If error occurs, then simulation must be repeated by changing either the

parameters of the VPL or the TXT file that was generated by Excel.

1.5.5 Real time measurement

Figure1.1 AirMagnet Software with Laptop

With the use ofAir Magnet software, real time measurements can be conducted to

measure the actual strength andpath loss of the signal.

Once the real time test has finished a comparison will be done with the predicted

result, the comparison will be in terms of path loss and time spread delay Upon this

comparison, an analysis can be done to evaluate the tested positions for Access

Points and Receivers to be located for best coverage Final recommendations can be

made to improve the performance of the network.


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Compare between

measured &

simulated results

Data Collection

Using AutoCAD

NO

Result Analysis

Collecting

parameters

Done

Measurements using

Air magnet software

Generate Excel files

Building database Receiver point databaseInterior building data base

YESSimulation

Using VPL

Success

UPDATING

DATABASE

Illustrate simulation

result using "MATLAB"

Site Survey

Figure1.2 Flow chart of the methodology


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For

Simulat

ion6

1.6 Organization of the Thesis

Chapter 1 contains some brief overview of WLAN systems In addition to this, the

problem statement , objective and the scope of the research have been described.

Finally, the flow chart of how the work of this project has been carried out was also

illustrated.

The literature review is performed in chapter 2. Some introduction about the

WLAN architecture and propagation paths and WLAN propagation mechanism are

introduced such as reflection, refraction, diffraction, delay spread and multipath

fading, the last part shows a summary of some related works.

Chapter 3 contains the some Propagation Models and brief explanation about

vertical plane launch method , the types of databases needed for the simulation are

described and some examples are provided also the outputs of the simulation

software are briefly described and the command input for the simulation software

have been provided.

Chapter 4 contains the results from VPL, result from AirMagnet software,

Visualization result in 2D by Matlab, in this chapter also include some analysis that

is done based on the wireless communication principles and fundamentals.

Finally, Chapter 5 contains the summary of the thesis and also includes some

suggestions for future work.


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CHAPTER 2

LITERATURE REVIEW

2.1 Wireless Local Area Network (WLAN)

2.1.1 Introduction

A wireless LAN or WLAN is a wireless local area network, which is the

linking of two or more computers without using wires. It uses radio communication

to accomplish the same functionality that a wired LAN has. WLAN utilizes spread-

spectrum technology based on radio waves to enable communication between

devices in a limited area, also known as the basic service set. This gives users the

mobility to move around within a broad coverage area and still be connected to the

network this technology is becoming more and more popular, especially with the

rapid emergence of small portable devices such as PDA (Personal Digital

Assistants)[4].

2.1.2 Benefits of Wireless LANs

Wireless LANs offer users an array of benefits ranging from cost efficiency

to seamless integration with other networks.


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called the SSID which is a 32 byte (maximum) character string. Example: linksys

(the default SSID for Linksys routers).

2.1.3.8 Distribution System

A distribution system connects Access Points in an extended service set. A

distribution system is usually a wired LAN but can be a wireless LAN.

Figure 2.2: Wireless Local Area Network Architecture using an Infrastructure BSS

2.2 IEEE 802.11 Standards

IEEE 802.11 is a family of specifications for WLANs developed by the

Institute of Electrical and Electronics Engineers. The 802.11 standard specifies the


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Parameters for both the physical and medium access control (MAC) layers of a

WLAN [3]. The physical layer handles the transmission of data between nodes. The

MAC layer consists of protocols responsible for maintaining the use of the shared

medium. Work on 802.11 began in 1987 within the IEEE 802.4 group.

There are three physical layers for WLANs: two radio frequency

specifications (RF -direct sequence and frequency hopping spread spectrum) and one

infrared. Most WLANs operate in the 2.4 GHz license-free frequency band and have

throughput rates up to 2 Mbps. There are various versions of the 802.11 standard. A

brief description of the more popular revisions is given below.

A. 802.11a: 802.11a operates at radio frequencies between 5 GHz and 6 GHz

[6]. The modulation scheme used is orthogonal frequency-division multiplexing

(OFDM). OFDM, also called multicarrier modulation, uses multiple carrier signals at

different frequencies, sending some of the bits on each channel. This is similar to

Frequency Division Multiplexing (FDM). The only difference between FDM and

OFDM is that in OFDM all the sub-channels are dedicated to a single data source.

The data rates vary based on the noise level, distance from the transmitting antenna,

and the propagation environment. Possible data rates for 802.11a are 6, 9, 12, 18, 24,

36, 48, and 54 Mbps. Maximum range for this standard is 200 feet.

B 802.11b: 802.11b often called Wi-Fi, being the most popular of all the

standards, operates in the 2.4 GHz frequency [7]. It is an extension of the 802.11

standard. Typical data rates for 802.11b are 5.5 and 11 Mbps. The modulation

scheme used is Direct Sequence Spread Spectrum. The chipping rate is 11 MHz, the

same as in 802.11, providing the same occupied bandwidth. Although the data rates

are slower than 802.11a, the range is higher, up to 300 feet. The frequency band used

(2.4 GHz) can have significant interference problems from such devices as

microwave, cordless phones, and Bluetooth devices.

C 802.11g: 802.11g is the newest member of the 802.11 family. This standard

combines the best of 802.11a and 802.11b. Like 802.11b, 802.11g operates in the 2.4

GHz frequency and can achieve ranges up to 300 feet, but like 802.11a, it reaches


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speeds up to 54 Mbps. 802.11g uses a hybrid complementary code keying OFDM

modulation [8].

D 802.11i: 802.11b uses Wired Equivalent Privacy (WEP) protocol to address

security concerns. WEP itself is more or less an implementation of encryption with

built-in message authentication and data integrity systems. The sheer number and

variety of vulnerabilities discovered within WEP shows what could arise when

security is not designed from the ground up. The future of wireless LAN security is

currently being entrusted to 802.11i [9] [10]. IEEE is developing this wireless LAN

standard, which focuses strictly on security and improving upon the protocols offered

by the previous 802.11 standards. There are three main areas that the IEEE 802.11i

wants to improve on over 802.11b: 1) authentication, 2) key management and 3) data

transfer. All of these areas were severely lacking in WEP.

Table 2.1: WLAN Standards

Protocol Release Date Frequency Bandwidth

IEEE 802.11 1997 2.4 GHz 1, 2 Mbps

IEEE 802.11a 1999 5 GHz

6, 9, 12, 18, 24,

36, 48, 54 Mbps

IEEE 802.11b 1999 2.4 GHz 5.5, 11 Mbps

IEEE 802.11g 2003 2.4 GHz6, 9, 12, 18, 24,

36, 48, 54 Mbps

IEEE 802.11n expected mid-2007 2.4 GHz 540 Mbps

2.3 Indoor Radio Wave Propagation

The propagated electromagnetic signal in the indoor environment can

undergo three primary physical modes. These are reflection, diffraction, and

scattering [3]. The following definitions assume small signal wavelength, large

distances (relative to wavelength) and sharp edges for a Typical indoor scenario. the

free space wavelength at 2.4 GHz is 4.92 inches. This wavelength relative to flat


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surfaces is sufficiently small for wave propagation mechanisms to hold true.

Typically, the distances between walls, floors and ceilings are on the order of 10 feet

or greater, and the office environment contains many vertical and horizontal edges

and surfaces.

2.3.1 Reflection:

The propagated signal striking a surface will either be absorbed, reflected, or

be a combination of both. This reaction depends on the physical and signal

properties. Physical properties are the surfaces geometry, texture and material

composition. Signal properties are the arriving incident angle, orientation, and

wavelength.

Figure 2.3a. Reflected Signal on partial reflective surface

Object surface

Figure 2.3b Reflected Signal on perfect reflective surface

Perfect conductors will reflect the entire signal. Other materials will reflect

part of the incident energy and transmit the rest. The exact amount of transmission


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and reflection is also dependent on the angle of incidence, material thickness and

dielectric properties. Major contributors to reflection are walls, floors, ceilings and

furniture.

2.3.2 Diffraction:

As shown in Figure. 2.4. A diffracted wave front is formed when the

impinging

Figure 2.4: Diffraction of a Signal

Transmitted signal is obstructed by sharp edges within the path. Diffraction

occurs when obstacles are impenetrable by the radio waves. Based on Huygens's

principle, secondary waves are formed Behind the obstructing body even though

there is no line of site [3]. Indoor environments contain many types of these edges

and openings, both orientated in the vertical and horizontal planes. Thus the resultant

diffracted signal is dependent on the geometry of the edge, the spatial orientation, as

well as dependent on the impinging signal properties. Such as amplitude, phase and

polarization. The result of diffraction of a wave at an obstacle edge is that the wave

front bends around and behind the obstacle edge. Diffraction is best demonstrated by

the radio signal being detected close to the inside walls around corners and hallways.

This phenomenon can also be attributed to the waveguide effect of signals

propagating down hallways.


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2.3.3 Refraction

The Figure 2.5 below shows Another phenomenon common to most radio

waves is the bending of the waves as they move from one medium into another in

which the velocity of propagation is different. This bending of the waves is called

refraction.

Figure 2.5: refracted wave

2.3.4 Scattering:

If there are many objects in the signal path, and the objects are small relative

to the signal wavelength, then the propagated wave front will break apart into many

directions. The resultant signal will scatter in all directions adding to the constructive

and destructive interference of the signal that is illustrated in Figure. 2.6 Most

modern office construction contains pressed steel I-beams throughout the wall

supports. Furthermore, construction materials such as conduit for electrical and

plumbing service can add to the scattering effect.


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Figure 2.6: Scattered Wave front on an I-beam

2.3.5 Indoor Path Loss

Path loss is difficult to calculate for an indoor environment. Again, because

of the variety of physical barriers and materials within the indoor structure, the signal

does not predictably lose energy. The path between receiver and transmitter is

usually blocked by walls, ceilings and other obstacles. Depending on the building

construction and layout, the signal usually propagates along corridors and into other

open areas. In some cases, transmitted signals may have a direct path (Line-of-Site,

LOS) to the receiver. LOS examples of indoor spaces are; warehouses, factory floors,

auditoriums, and enclosed stadiums. In most cases the signal path is obstructed.

2.3.6 Free Space Loss

Fundamental to indoor path loss analysis is the free space loss. If the

transmitting antenna were ideally a radiating point source in space, the propagated

surface wave front will exit the point source in a spherical pattern as shown in

Figure. 2.7. The spherical signal energy reduces as the square of the distance. FreeSpace Path Loss (FSPL) is defined as: Spherical radiating wave front


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Fig. 2.7- Free Space Radiating Point Source

2)4

(

dFSPL

= (1)

Whered is distance in meters between the transmitter and receiver, and (lambda) is the wavelength in meters. This equation also implies that as the

frequency increases the loss will be proportionally higher. Relating frequency to

wavelength:

f

c= (2)

Where c is the speed of light, m/s, and frequency, f = cycles per

second.

8103=c

The wavelength of the 2.4 GHz sinusoid is:

=0.125 meters,=12.5 centimeters or=4.92 inches.Free space loss defined in decibels is :

Free Space Loss = 10 log (FSPL) (3)

Where FSPL is from equation 1.

Free Space Loss (FSL) = 40 dB @ 1 meter

Accordingly, the Free Space Loss (FSL) = 60 dB @ 10 meter Therefore, the

free space loss 1 meter away from the transmitter is 40 dB! Thereafter, the signalattenuates at a rate of 20 dB per decade.


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2.3.7 Line of Site Path Loss

For a LOS office scenario, the path loss is given

Figure 2.8 - 2.4GHz Typical Path Loss

(4)

Where FSLref is the free space loss in dB determined in the far field of the

antenna. Usually for indoor environments, this is calculated to be 1 or 10 meters as

shown in equation (3). dtr is the distance between the receiver and transmitter. The

symbol n1 is a scaling correction factor which is dependent on the attenuation of

the propagation environment. In this case, equation (4) is for large indoor spaces.

The n1 factor has been determined from empirical data collected and can be found in

the excellent reference by; [2] T. Rappaport. For line of site application in hallways

the n1 factor has been determined to be less than 2. This is due to the waveguide

effect provided by properties of hallways or corridors. Figure 2.8 shows the free

space attenuation in dB for a typical indoor application. The curve represents variousLOS path losses. The first segment represents the path loss due to free space. The

second and last segments represent a more lossy path. The instantaneous drop

demonstrates the loss due to obstruction of the LOS path.


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2.3.8 Obstructed Path Loss

Obstructed path loss is much more difficult to predict, especially for the

myriad of different indoor scenarios and materials. Therefore, different path loss

models exist to describe unique dominant indoor characteristics. Based on free space

loss and the three propagation phenomenon, the path loss models also account for the

effects of different building types. Examples are multi-level buildings with windows,

or single level buildings without windows.

Figure 2.9: Multiple Floors Indoor Path Loss

It has been shown (See Figure. 2.9) that the propagation loss between floors

begin to diminish with increasing separation of floors non-linearly. The attenuation

becomes less per floor as the number of floors increases. This phenomenon is

thought to be caused by diffraction of the radio waves along side of a building as the

radio waves penetrate the buildings windows. Also, a variety of different indoor

configurations can be categorized for buildings with enclosed offices, or office

spaces consisting of a mix of cubicles and enclosed rooms. Examples of attenuation

through obstacles for various materials are shown in the table below.

Indoor path loss has been shown to be exponential as shown in Fig. 2.8. In

specific cases the models can show deterministic limits. However, in majority of the

cases the obstructed path loss is determined through empirical means followed by

corresponding refinements to the mathematical model.


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Table 2.2: 2.4 GHz Signal Attenuation

Window Brick Wall 2 dBMetal Frame Glass Wall into Building 6 dBOffice Wall 6 dB

Metal Door in Office Wall6 dB

Cinder Block Wall 4 dBMetal Door in Brick Wall 12.4 dBBrick Wall next to Metal Door 3 dB

2.3.9 Doppler frequency shift

When a signal source producing waves at a frequency f and an observer

move relative to one another, the frequency measured by the observer (f) depends

on the details of the relative motion; this change in frequency is known as the

Doppler Shift.

The Doppler shift equations shown below work for any wave moving in a

medium, when the motions of the source and observer are along the line joining

them. In the equations below, v, vo, and vs,are the speeds of mobile unit, observer

and source relative to the medium; if the medium (e.g. air) is moving, vo and vs

should be measured with respect to the medium.

If the observer is moving and the source is stationary, the measured frequency

is:

f = f(v v

O)

v

(1)

where the upper sign corresponds to an approaching observer and the lower

sign corresponds to a receding observer.

If the source is moving and the observer is stationary, the measured frequency

is:

f = fv

(v m vS )(2)


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where the upper sign corresponds to the source approaching and the lower

sign corresponds to the source receding from the observer.

More generally, where both the source and observer are moving:

f = f(v v

O)

(v m vS)

(3)

Note that the signs in the numerator and denominator are independent of each

other. Use the following general rules for the signs: in the numerator, the upper sign

is used if the observer is moving towards the source and the lower sign if moving

away from the source; in the denominator, the upper sign is used if the source is

moving towards the observer and the lower sign if moving away.

An easy way to remember the signs is simply to remind oneself whether or

not the the observed frequency is going to want to increase or decrease and use

whichever signs do that. For example, when an observer is moving away from a

source, the waves are going to move across it at a slower rate than if it was sitting

still, which means the observed frequency is going to decrease. In order for that to

happen mathematically, the numerator in Eq. (3) needs to decrease, so clearly we

want to use the (-).

Similarly, if a source is moving toward an observer, its going to smoosh

the waves together as it emits them, which means an increase in observed frequency.

This will be accomplished by making the denominator in Eq. (3) smaller, which

requires using the (-) again.


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Figure 2.10: Doppler frequency shift effect

2.3.10 Multipath and Fading Effects

Figure 2.11: Multipath signal in indoor environment


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As a transmitted radio wave undergoes the transformation process presented

in the indoor Environment it reaches the receiving antenna in more than one path,

thus giving rise to Multipath. Relating Multipath to propagation models and path loss

employs stochastic theory and probability distribution functions (PDF). A somewhat

understated view of the Multipath effect is; signal variations within a building, where

there are no clear line of site signal paths between the receiver and transmitter,

approximate a Rayleigh distribution. For receivers and transmitters that have line of

site signal paths, the distribution is Rician[3].

A Rayleigh distribution function describes a process where a large number of

incident rays (as seen at the receiver antenna) add randomly with respect to

amplitude and time. A Rician distribution is similar to a Raleigh PDF except that a

Rician PDF contains a strong dominant component. Usually the dominant component

is the direct line of sight or ground reflection ray [5].

Multipath introduces random variations in the received signal amplitude over

a frequency bandwidth. Multipath effects also vary depending on the location of the

antenna as well as the type of antenna used. The observed result of random signal

distributions, as seen by the WLAN radio receiver, will be the in and out variation

(fading) of the signal (See Figure 2.12). Variations as much as 40 dB can occur.

Fading can be very rapid or slow. This depends on the moving source and the

propagation effects manifested at the receiver antenna. Rapid variations over short

distances are defined as small-scale fading. With respect to indoor testing, fading

effects are caused by human activities and usually exhibit both slow and fast

variations. Sometimes oscillating metal bladed fans can cause rapid fading effects.

Applications of the WLAN radio indoors can either be fixed or mobile. Thus, small-

scale fading effects can be further described using Multipath time delay spreading.

Since the signal can take many paths before reaching the receiver antenna, the

signals will experience different arrival times. Thus, a spreading in time (as well as

frequency) can occur. Typical values for indoor spreading are less than 100

nanoseconds. Different arrival times ultimately create further degeneration of the

signal. Finally, those who are involved in the wireless discipline whether as a

designer or a user must be aware of construction materials, interiors and exteriors,


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and locations of a building to best position WLAN radio equipment. For optimal

performance the user should also consider work activities ultimately.

Figure 2.12 - Small Scale Fading

The WLAN user needs to understand the relationship between indoor propagation

effects and how WLAN performance is affected.

2.3.11 Delay Spread

Because ofmultipath reflections, the channel impulse response of a wireless

channel looks likes a series of pulses. In practice the number of pulses that can be

distinguished is very large, and depends on the time resolution of the communication

or measurement system.

Figure 2.13 Impulse response and frequency transfer function of a multipath

channel.

In system evaluations, we typically prefer to address a class of channels with

properties that are likely to be encountered, rather than one specific impulse
http://wireless.per.nl/reference/chaptr03/fading/fading.htmhttp://wireless.per.nl/reference/chaptr03/fading/fading.htm


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response. Therefor we define the (local-mean) average power which is received with

an excess delay that falls within the interval (T, T+ dt). Such characterization for all

Tgives the "delay profile" of the channel.

The delay profile determines the frequency dispersion, that is, the extent to

which the channel fading at two different frequenciesf1 andf2 is correlated.

2.3.12 Raleigh Fading

Rayleigh fading , also called fast fading , is commonly used to describe

multipath fading in a two way radio communication system that occurs when there id

not a clear path between the transmitter and the receiver . Rayleigh fading describes

the statistical distribution of the radio signals power as received by a radio receiver.

Rayleigh fading occurs when two or ore waves from the transmitter are reflected and

form standing wave pairs in space, when the standing pairs occur, the signals are

summed in amplitude, which causes irregular signal strength variations, which then

usually results in a reduction in signal strength.

Rayleigh fading occurs when the receiving antenna moves through

constructive wave fronts. The receivers susceptibility to fading is a function of

frequency of oration and the receiver bandwidth. the higher the frequency , the

shorter the distance id between wave crests, the wider the bandwidth, the susceptible

the receiver is to fading . a value of 5dB is typically used in accounting for Rayleigh

fading in the link budget.

2.3.13 Rician Fading

Rician fading describes the statistical energy distribution of direct wave path

from a transmitter to a receiver. This is also referred to as the light of sight path, and

it represents the variation in signal strength that occurs when the path from a

transmitter to a receiver is not obstructed . Rician fading describes a condition thatoccurs when one dominant signal arrives at the receiver with several other weaker
http://wireless.per.nl/reference/chaptr03/cohbw/cohbw.htmhttp://wireless.per.nl/reference/chaptr03/cohbw/cohbw.htm


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multipath signals. Rician fading is not that common in two way communication

because building or other objects usually obstruct a line of sight to the source.

2.3.14 Related works

A lot of works has been done on the radio propagation prediction. Although

the concept is the same, a lot of techniques has been proposed by a lot of reseachers.

In this section, some of the previous work is introduced to illustrate these diiferent

techniques for prediction. This will eventually lead to fully understanding the

propagation prediction measurements.

Martin , Stanislav and Pavel (Technical University ,Ireland) ,They srarted on

a site survey based on empirical measurements or planning using a software tool

with build-in signal propagation models.

Measurement Equipment

1- RF-Site Survey Software Tool

2- Measurement system by Symbol

Figure 2.14 Measurement system by Symbol

They investigated two models of propagation redictions These Methods are:

1- 1-Manual Deployment using A Site Survey based on Empirical

Measurements (Network is Up and running )

2- 2-Using Software Tool with built-in Signal propagation models


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The first method is based on the empirical and semi-empiricalmodels which

are primarily based on statistically processed representative measurements. As the

most popular examples, One-Slope and Multi-Wall models .

In the second one, it is more based on software planning (using a propagation

model) which is much more convenient and cost-effective way to deploy a wireless

network than a site survey with lots of measurements and empirical decisions. Using

simulations many different configurations of the network can be tested with no

expenses to find an optimal solution.

The Measurements that were conducted during the test are RSSI, Coverage ,

Data Rate , Signal quality. The fillowing graphs illustrated some of these

measurements.

Figure 2.15 :signal level without pepole

Figure 2.16 :signal level with present pepole

At first, the measurements were performed without the presence of people.

The doors were opened and closed and the orientation of the notebook was changed

in order to nvestigate how it would distort received signal strength. In the Figure .

2.16 and 2.17 the 5 dB variations due to the "door state" can be clearly seen. Few

high attenuation peeks were caused by a sporadic movement of people at the corridor

which was difficult to prevent even in such a limited area.


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Figure 2.17: effect opening and closing the door

It is understood from the graph that the effect opening and closing the door

can be even more distinct when hand-held device is used. The influence on how it is

held, i.e. shadowed by a user, is tremendous. This will give us a real picture of how

accurate our measurements can be.

Eventaully, they have came with these conclusions; Empiriacal measurements

are more precise since they include real environment e.g. people movement , doors

open and closed

However, it is very time consuming (expensive) and usually it is feasible to

perform measurements in limited number of location .

They have recommended for reliable network, both of these methods might

be used in order to fully get an optimised network. In the next table, a summary of

some papers survey is illustrated.

Two main options are available for the implementation of a ray tracing

model known as ray launching , and point to point ray tracing .


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Table 2.3 diffierent Between two types of ray tracing models

MMeetthhoodd Raytracing p to p Ray launching

AAddvvaannttaaggee More accurateSimple computational

time

DDiissaaddvvaannttaaggeeExtremely high

computational time

Less accurate

For the measurements of the ray tracing, it is a commonly used computational

method for site specific prediction of the radio channel characteristics of wireless

communication system. this provides time delay and path loss of the arrival

information for multi path reception condition.


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CHAPTER 3

RAY TRACING SOFTWARE AND SIMULATION

3.1 Propagation Models

3.1.1 Two-Ray tracing Model

Site specific propagation models are based on electromagnetic-wave

propagation theory to characterize indoor radio propagation. Unlike statistical

models, site specific propagation models do not rely on extensive measurement, but a

greater detail of the indoor environment is required to obtain an accurate prediction

of signal propagation inside a building. In theory, electromagnetic-wave propagation

characteristics could be exactly computed by solving Maxwells equations with the

building geometry as boundary conditions. Unfortunately, this approach requires

very complex mathematical operations and requires considerable computing power,

beyond that of current microcomputers. Hence it is not economical for the

characterization of indoor radio wave propagation. Therefore, approximate numerical

methods are of interest. Ray tracing is an intuitively appealing method for calculating

radio signal strength, time-invariant impulse response, root mean square (RMS)

delay spread and related parameters in an indoor environment [12].

The concept of ray-tracing modeling is based on the fact that high-frequency

radio waves behave in a ray-like fashion. Therefore, signal propagation can be

modeled as ray propagation. By using the concept of ray-tracing, rays may be


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(3.1)

Where Pt is the transmitted power, r1 is the direct distance from the transmitter to the

Receiver, r2 is the distance through reflection on the ground, and ( ) is the

reflection coefficient depending on the angle of incidence and the polarization.

The reflection coefficient is given by

(3.2)

Where = 90- and a = 1/ or 1 for vertical or horizontal polarization,

respectively. r Is a relative dielectric constant of the reflected surface the signal

strengths from theoretical and empirical models.

3.1.2 Vertical-Plane-Launch MethodVertical-Plane-Launch (VPL) method provides a full three dimensional (3-D)

solution with computationally fast way to determine contributing rays and yields an

accurate propagation prediction. The VPL method considers specular reflections

from vertical surfaces and diffraction at vertical edges. It also allows approximation

of diffraction at horizontal edges along the plane of incidence.

The advantage of the VPL over full 3-D shoot and bounce ray (SBR) method

is that it can handle many multiple forward diffraction at horizontal edges. Besides

this, the VPL method provides many other advantages. The VPL method is

applicable for rooftop antenna and areas with mixed building heights that can not be

properly handled by vertical-plane/slant-plane (VP/SP) approximation[14].

The VPL method applies standard shoot and bounce method only at thehorizontal plane and use deterministic approach to determine the vertical


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displacement of ray paths. This method is based on assumption that building walls

are approximately almost vertical.

Figure 3.2 indicates that 2-D rays are generated in horizontal directions from the

source. This method generates a binary tree at intersection point of vertical plane and

exterior surface of building at intersection point, two planes are generated where one

follows the incidence direction and the other one follows the direction of specular

direction.

The vertical path direction can be found based on buildings profile and use

deterministic equation to calculate the vertical displacement and received signal

strength.

Figure 3.2: Ray generation in horizontal plane (Liang and Bertoni 1998)

3.1.3 Algorithm of Simulation Software

The ray architecture is described by the flow chart shown in the Figure 3.3,

the program architecture is divided into three modules that are found intersections

with walls module, find receiver module, and find diffracting corner module.


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hence away from the building and receivers. These simplifications are made because

it is believed that the rays do not contribute to the total received power in a micro

cellular environment, or they occur very infrequently, and their inclusion would

substantially increase the model complexity and computation time.

3.2 Databases for Simulation

There are four types of databases needed to run this simulation completely:

building database, receiver database Interior building database and antenna radiation

pattern database. The building database gives relative location of the building within

the predication area, whereas the receiver database contains the coordinates of the

receiver points. Interior building database is used to model the effect of the building

details on the ray path. Antenna radiation pattern database gives the radiation pattern

of the antenna at every one degree. Since we use monopole antenna and transmitter

and receivers inside a building, terrain elevation database and antenna radiation

pattern database will be ignored, while building interior database will be used [15].

3.2.1 Building database

The building database is comprised of a single American Standard Code for

Information Interchange (ASCII) file which contains six columns of integer and

floating point numbers that represent the building. The first column is a unique

building identity number that must be different from the building number before and

after. The second and third columns are the X and Y coordinates are entered as a

relative position from some arbitrary fixed reference position of the database

coordinate system.. The fourth column is the Z coordinates which representing the

height of the top of the building above the reference plane and the fifth column is Z

which representing the vertical distance that the corner of the building extends

downward from Z, are assigned to each (X; Y) point, while final column in the


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database is representing the relative dielectric constants. The recommended

dielectric constant is 6 because it provides the least error compared to value [15].

Figure 3.4: sample of the AUTOCAD Building map of WCC

Table 3.1:part of WCC building database

Building ID X Y Z Z PL

1 24.961 2.5 3 3 6

1 38.887 2.5 3 3 6

1 38.887 12.937 3 3 6

1 38.072 12.937 3 3 61 38.072 14.637 3 3 6

1 38.887 15.062 3 3 6

1 38.887 26.844 3 3 6

1 24.961 26.844 3 3 6

1 24.961 2.5 3 3 6

2 30.352 20.672 3 3 6


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3.2.2 Receiver Database

The receiver file is also in multi-column format, with each line containing

the coordinates of a single receiver point. The first column represents the receiver

number and the following three columns represent the location of the receiver in x,y

and z coordinates, with respect to the building database coordinate system. The z

value of the receiver point is the height of the ground at the point and not absolute

height of the receiver. The height of the receiver above the ground, which is

specified by the user, is added to the z value to get the height of the receiver [15].

Receiver point

Figure 3.5: AutoCAD Receiver location map

Table 3.2: Example of the receivers database

RX ID X Y Z

1 30.87 19.492 0.79

2 30.87 17.972 0.79

3 31.57 20.172 0.79

4 33.57 20.172 0.79


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5 35.57 20.172 0.79

6 37.57 20.172 0.79

7 38.405 19.472 0.79

8 38.405 18.472 0.79

9 38.405 17.472 0.79

10 30.87 13.242 0.79

11 30.87 12.242 0.79

12 30.87 11.243 0.79

13 32.567 10.572 0.79

14 34.567 10.572 0.79

15 31.57 21.172 0.79

3.2.3 Building Interior Database Format

When the floor plan of building is not known but propagation into the

interior of a building is desired it is possible to assume some assume some average

characteristics of the building. The loss associated with this general description of

the building is due mostly to the penetration through the exterior face and the interior

walls of the building. The first number represents the building and must be a integer

number. The number should correspond with the same building number as the one

being described in the building database file.

The next three numbers represent the average height of each floor, the

height of the first (or ground floor), the average width of the rooms. The following

three numbers represent the type of interior wall, type of floor and the type of

exterior walls and must be integers. Currently, the numbers that represent the wall

and floor types are use directly to determine the penetration loss. In words a wall or

floor with a number 8 means that there is -8dB of loss associated with propagation

through this material [15].


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Table 3.3: Interior building database

.

1 3 3 25 4 8 10 10 0

Number of

Building

Average height offloor and average

width of rooms

Type of wall due

to penetration loss

Number ofelevator

2 3 3 8 4 8 10 10 0

3 3 3 8 4 8 10 0.4 0

4 3 3 8 4 8 10 1 0

5 3 3 8 4 8 10 1 0

6 3 3 8 4 8 10 10 0

7 3 3 8 4 8 10 1 0

8 3 3 8 4 8 10 10 0

9 3 3 8 4 8 10 10 0

10 3 3 8 4 8 10 10 0

11 3 3 8 4 8 10 10 0

12 3 3 8 4 8 10 10 0

13 3 3 8 4 8 10 10 0

3.3 Simulation Command Input

The ray tracing program is run in DOS mode where it performs command

line execution. Three arguments are required to initialize the program with a fourth

argument being optional as shown in the first command input in Table 3.4. The first

argument is building database file name, the second argument is receiver location file

name and the third argument is output file name. The optional input is the

preprocessed data file name. The associated directory of each file name must be

defined correctly. After the program has been initialized correctly, two lines of

information are displayed as second command input in Table 3.4. If the

preprocessed input file name is not given at the initialization stage, a question will

prompt user to decide whether to have a preprocess run again [15].


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Then, the program starts requesting a series of input parameters as listed in

Table 3.4

3.4 Output of the Prediction Tool

There are 3 type of output that can be generated by the prediction program.

They are power and delay spread output, impulse response output, and ray paths

information output. Either power or delay spread output or impulse response output

files. On the other hand, ray path information outputs that contain the individual ray

paths for the receivers can be obtained together with any of the two output files. The

details of the output files are presented in the next chapter.

Table 3.4 simulation Command input

NO Command Input

1 C:\...\runvpl

[

2 Site Ware Technologies, Inc.

Site Specific Propagation Prediction Tool, ver 1.0 28SEP99

No preprocessed file was specified.

Do you want to do a preprocess run? [y/n] n

3 Enter the angle that the ray trace will increment by: 1

4 Enter the maximum number of reflections to calculate: 10

5 Enter the number of diffractions at vertical edges that will be computed: 2

6 Enter the number of operating frequencies: 1

7 Enter the value of frequency 1 [MHz]: 2450

8 Enter the Fresnel zone width used to test screens: 1

9 Consider terrain using digital elevation database? [y/n]: n

10 Compute with 2 ray model? [y/n]: n

11 Impulse Response or Power & Delay Spread Output? [i/p]: p


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12 Is a directional antenna used? [y/n]: n

13 Output individual ray path data? [y/n]: y

14 The ray paths for each receiver is in file `ray_paths___'

15 Enter the x coordinate of the transmitter: 33.38

16 Enter the y coordinate of the transmitter: 20.47

17 Enter the z coordinate of the transmitter: 2.5

18 Number of different transmitter heights at (20,30,50): 1

19 Enter height 1 of the transmitter: 0.3

20 Enter the height of the receivers: 0.1

Figure 3.6: Command input simulation


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CHAPTER 4

RESULTS AND DISCUSSION

4.1 Overview

This chapter will discuss the simulation results and the comparison between

the simulation and the real time measurements of the propagation prediction for the

WALN system in the main campus of universiti tekonologi Malaysia . The study of

the indoor propagation environmentis done in order to obtain the good accuracy,

efficiency and coverage of signal strength, a simulation firstly is done within a

mobile lab, corridor and area around inside WCC in the second stage our target was

a multistory building (kolej perdana) and in the third stage the propagation

prediction was done for (kolej 11 building MA7).

4.2 Output Result from VPL SoftwareThere are 3 types of outputs generated by VPL software. They are power

and delay spread output, impulse response output, and ray paths information.

Output. The type of result can be choose during software run, if user request the ray

path information to be saved, that will be 2 types output file. The results from power

and delay spread or impulse response out put with ray path information for every

receiver. The result of each type of output will be described in the followingsections for each type of results.


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4.2.1 Power and Delay Spread Output

This output file contains the predicted path loss for receivers, a section that

contains the different components that add together to get the total power received,

rms delay spread and mean excess delay. The results for each receiver are listed in a

multicolumn format on a single line with brief heading describing the program

execution parameters. Below the headers, the first column represents receiver

numbers while second to fourth columns list the x, y, and z coordinates for those

receivers. The fifth column is the predicted path loss value in dB. The column after

in between vertical line (|) Separators is breakdown of the total power received into

its separate components. The first two columns indicate value in watt and number of

LOS rays, the second two columns show value in watt and number of reflected rays

that arrived at receiver. The third and forth two columns indicate value in watt and

number of rays that undergo 1 and 2 vertical edge diffraction beside on top of

reflection. The final two columns of data represent the rms delay spread and the

mean excess delay in seconds.

4.2.2 Impulse Response Output

In this result, the header is same with the one used for the power and delay

spread. Below the header is the individual path information according to the

receiver. The first line is the receiver number and the x, y, and z coordinates of the

receiver. Listed below the receiver are the individual rays contributed at the receiver.

The columns represent the angle at which the ray left the transmitter and path length

of the ray in meters, the propagation time in seconds and the predicted path loss in

dB. The fifth and final column is numerical representation of the type or class of

ray.

4.2.3 Ray Path Information Output

The ray path information is stored in separate file for each receiver in every


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Simulation these outputs generate details of each ray path that arrive at a particular

receiving point. Each group of information starts with a # sign heading representing

a single ray path. The heading with a # sign shows the total path length and total

path loss associated with the ray. Information below the heading is a list of x, y, and

z coordinates for all ray segments that combine together to form a complete path

from source to receiving point. The number of ray paths that arrives at a particular

receiving point is depending on the simulation output.

Example of the power and delay spread output

Header

Meanexcessdelay

DelaySpread

Power received fordifferent components

PathLoss

Receivercoordinate

Receivernumber

Figure 4.1: Example of power and delay spread output


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Receivernumber andcoordinate

Path lossdB

PropagationTime

(seconds)

PathLength(meter)

Angle ClassOf ray

Figure 4.2: Example of impulse response output


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Coordinate

For all raySegments

Length andpath loss ofEach ray

Figure 4.3: Example of ray path information output


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4.3 Measurements result using AirMagnet

AirMagnet Software compute many type of data, IP address for access point,

signal strength, level of noise, speed, packet loss and packet retried as shown in

Figure 4.4. This data will generate to every receiver with number of output depend

to the time that use to catcher data , after that take the average of data and compare

them with result that obtain from VPL software.

Measurement Loss

for location RX-59

Figure 4.4 Example of AirMagnet measurement (Kolej Perdana)

The figure 4.4 shows the measurement in one location which is in this case location

RX-59 this receiver point have a predicted path loss -80.96 dB and real time

measurement using AirMagnet software about -80 dB , a comparison between the

predicted path loss and real time path loss will be shown later for 19 receiver point


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4.4 Result Visualization

Matlab is a high level technical computing language and interactive

environment for algorithm development, data visualization, data analysis, and

numerical computation. It includes a set of low-level file input output (I/O)

functions that are based on the I/O function of the American National Standards

Institute (ANSI) Standard C Library.

Matlab was used to extract data from the numerical input and output file

from the VPL ray tracing software. The data are then presented in a 2D graphic

display.

4.4.1 Path Loss and Time delay spread Visualization for WCC

Figure 4.5 Simulation Path Loss for Mobile Lab room (WCC)


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Figure 4.6 Time delay spread for Mobile Lab room (WCC)

Figure 4.7 Simulation Propagation predictions Path Loss for (WCC)


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Figure 4.8 Time delay spread for WCC

4.4.2 Path Loss and Time Delay Spread For KOLEJ PERDANA

Figure 4.9 Kolej Perdana First floor Path loss propagation predication at 2400MHzCarrier Frequency


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Figure 4.10 Kolej Perdana Second floor Path loss propagation predication at2400MHz Carrier Frequency

Figure 4.11 Kolej Perdana Third floor Path loss propagation predication at

2400MHz Carrier Frequency


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Figure 4.12 Kolej Perdana Forth floor Path loss propagation predication at2400MHz Carrier Frequency

Figure 4.13 Kolej Perdana Fifth floor Path loss propagation predication at 2400MHzCarrier Frequency


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Figure 4.14 Kolej Perdana Sixth Floor Path loss propagation predication at2400MHz Carrier Frequency

na Seventh Floor Path loss proFigure 4.15 Kolej Perda pagation predication at

2400MHz Carrier Frequency


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Figure 4.16 Kolej Perdana All the seven Floors Path loss propagation predication at2400MHz Carrier Frequency

Figure 4.17 Kolej Perdana-One Floor Path loss propagation predication at2400MHz Carrier Frequency

(Based on assumption that the building is only one floor)


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Figure 4.18 Kolej Perdana One Floor Path losses Comparison between 1 ray (blue)model and 2 ray model (red) propagation predication at 2400MHz Carrier Frequency

Figure 4.19 Time delay spread for the First Floor Kolej Perdana


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Figure 4.20 Time delay spread for the Second Floor Kolej Perdana

Figure 4.21 Time delay spread for the Third Floor Kolej Perdana


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Figure 4.22 Time delay spread for the Fourth Floor Kolej Perdana

Figure 4.23 Time delay spread for the Fifth Floor Kolej Perdana


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Figure 4.24 Time delay spread for the Sixth Floor Kolej Perdana

Figure 4.25 Time delay spread for the Seventh Floor Kolej Perdana


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-40

Figure 4.28 Time delay spread for all the four Floors Kolej 11 MA7

4.5 Result Analysis

4.5.1 Path Loss and Time Delay Spread

The effects of the fading due to Multipath reception condition in the indoor

environment is the main problem , firstly the propagation prediction was done in one

floor building (WCC) the results of the Path Loss and Time delay spread are presented The Figure 4.5 and Figure 4.6 , Figure 4.7 , Figure 4.8 shows that the

maximum path loss was about (-76 dB ) which is very acceptable for good coverage

, the time delay spread output as in the graphs usually the first arrival signals must

have less error due to less number of paths that the signal must go through before it

reaches the receiver point.

Secondly the Figures from number 4.9 to 4.15 shows the predicted path loss

for Kolej Perdana building its clear form this graphs that the effect of the multifloor

10-13

10-12

10-11

10-10

10-9

10-8

-60

-80

-100

-120

-140

-160

-180

4 Floors Time delay spread

Time in (n sec)

Path

Loss

(-dB)

10-7


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factor (penetration from ceiling) was from 1 dB loss to 25 dB loss depends on the

transmitter location and the material of the ceiling used . a comparison between the 7

floors are presented in Figure 4.16, the figure 4.17 One Floor Path loss propagation

predication at 2400MHz Carrier Frequency (based on assumption that the building is

only one floor) and the figure 4.18 shows one floor Path loss comparison between 1

ray model (blue) and 2 ray model (red) propagation predication at 2400MHz carrier

frequency, figures from number 4.19 to 4.25 shows the different of arriving time for

the signal in every single floor and the Figure number 4.26 shows the time delay

spread for are the 7 floors together , also figure 4.27 shows Kolej 11 building MA7

all the four floors path loss propagation predication at 2400MHz carrier frequency

From this figure we see that the effect of the multifloor factor is almost the same due

to the similarity of the ceiling material and the complexity of the building

architecture, figure 4.28 shows the time delay spread for the MA7 building.

4.5.2 Comparison between Prediction and Measurement Result

Figure 4.29 comparison between real-time measurements and simulation for

Kolej Perdana


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From Figure 4.29 for This comparison have carried out for 18 receiver point

in Kolej Perdana among the corridor the comparison between prediction and

measurement result, we find that loss from both in good agreement except some

receiver point due to Multipath fading effect phenomena, when signals arrive to

receives there are usually a combination of direct and indirect path, if

electromagnetic phase of signal same will make signal strength because it is sum of

this phase and if the electromagnetic phase for signals shift of inverse will drop

signal strength.


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CHAPTER 5

CONCLUSION

5.1 Conclusion

This chapter concludes all the work that has been carried out in this project. It

summarizes the targets achieved and shows how well this work can contribute to give

full understanding of how the propagation prediction can be done using software

based on ray tracing model for WLAN system. Also, it provides some suggestions for

future work that can help to improve this project.

The study on the indoor environmental effect, which affect the radio wave

propagation and visualization of the radio wave propagation with 2 dimensional

introduces effect of reflection, diffraction, multipath fading, also the time delay spread

and Path loss of the propagation mechanism are presented, the main issue that effects

the signal coverage in multistory building was the multifloor factor which was clear

from the obtained results.

Indoor wireless LAN coverage can be done based on the said study and the

experiments, in our days WLAN is important technology to provide higher data rate

to the indoor user.

The Indoor propagation prediction is crucial to optimize coverage prediction

and characterize indoor channel parameters.

Field measurements have been carried out to verify the simulation results.


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In the first stage of this project one floor building (WCC) was simulated for

the propagation prediction to see how the signal will be affected in such complex

office. After that in the second stage our target was multi-storey building with

complex indoor architecture (Kolej Perdana) to see how the multifloor factor can

effect the signal and also we have simulated another multi-storey building which is

near in complexity to the Kolej Perdana building which was Kolej 11 MA7 building

to see weather the effects of multifloor factor is the same or not.

5.2 Future Work

A lot of ideas can be suggested in order to improve the present work. Some of

these useful suggestions are the signal propagation prediction can be extend to bigger

area with number of single and multiple storey buildings and simulate for outdoor

transmitters to indoor receivers and vise versa .

Further investigations are needed to produce similar results for different types

of indoor environment such as office, factory or any other indoor structure also

another important issue can be considered, in order to get more accuracy which is the

effect of presence of people inside the building and the effect of the doors status

(closed or opened).

Comparison between different indoor propagation models that are currently

proposed can be done. And from the study a new channel model can be developed

which could be used for wireless networks, to provide optimal performance in a local

indoor environment.


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[9] IEEE. Wireless LAN medium access control (MAC) and physical layer

(PHY) specifications Amendment 6: Medium Access Control (MAC) security

enhancements.IEEEStandard 802.11i, 2004.

[10] J. C. Chen, M. C. Jiang, and Y. W. Liu; "Wireless LAN security and IEEE

802.11i Wireless Communications", IEEE, 12:2736, February 2005.

[11] Jorgen Bach Andersen, Theodore s

indoor propagation prediction and measurements within multistory building for wireless lan...

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