PROPAGATION MEASUREMENTS AND PREDICTOIN FOR INDOOR WLAN APPLICATION

IBRAHIM .M. ABDALLA ABOHARBA

A thesis submitted in fulfillment of the requirements for the award of the degree of

Master of Engineering

Faculty of Electrical Engineering Universiti Technologi Malaysia

MAY 2006

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To my beloved father, Mokhtar Aboharba and mother Fatemh Salm

To my brothers and sisters

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ACKNOWLEDGEMENT

In preparing this thesis, I was in contact with many people, researchers,

academicians, and practitioners. They have contributed towards my understanding

and thoughts. In particular, I wish to express my sincere appreciation to my thesis

supervisor, Professor Dr. Tharek abd. Rahman, for his encouragement, guidance,

advices and motivation.

I would like to thank friends and staff in Wireless Communication Center (WCC) for

their help, facilities and for providing conducive working environment.

Finally, I am deeply and forever indebted to my parents, brothers and sisters

for their love, spiritual support and encouragement throughout my entire life.

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ABSTRACT

The application of wireless local area network (WLAN) is increasing in

offices, it become important to study signal propagation indoor environment. In this

project, the Site Ware Technologies` 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 in Wireless Communication Center (WCC), Faculty of

Electrical Engineering, University Technology Malaysia (UTM). Propagation

prediction will be done within first floor of WCC at carrier frequency 2.4 GHz based

on IEEE 802.11 b/g standard while measurement of signal strength will use

Airmagent software for measure above mention area. after that presented simulation

result into three dimensional using Matlab software .

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ABSTRAK

Kajian mengenai perambatan isyarat kawasan bilik dalaman menjadi semakin

penting dengan penambahan penggunaan WLAN dalam pejabat. Dalam projek ini,

“Site Ware Technologies” adalah ramalan perambatan tiga dimensi (3-D) kod

pengesan sinaran memerlukan cara “modified shoot” dan “bounce ray (SBR)”

dikenal sebagai “Vertical Plane Launch (VPL)” akan digunakan untuk meramal

perambatan dalam bangunan Pusat Komunikasi tanpa Wayar (WCC), Fakulti

Kejuruteraan Elektrik (FKE), Universiti Teknologi Malaysia (UTM). Ramalan

perambatan akan dilakukan pada tingkat 1 di bangunan WCC pada pembawa

frekuensi 2.4 GHz yang berdasarkan piawaian IEEE 802.11 b/g manakala

pengukuran kekuatan isyarat di tempat yang dinyatakan diatas adalah berdasarkan

kepada perisian Airmagnet. Selepas itu, keputusan simulasi akan dipersembahkan

dalam tiga dimensi (3-D) dengan meggunakan perisian Matlab.

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LIST OF CONTENTS

CHAPTER TITLE PAGE

TITLE i

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES xii

LIST OF FIGURES xiii

LIST OF SYMBOLS xvi

LIST OF APPENDICES xxi

1 INTRODUCTION 1

1.1 Overview 1

1.2 Problem Statement 1

1.3 Wireless LAN 2

1.3.1 Introduction 2

1.3.2 Wireless LAN Standards 3

1.3.2.1 802.11 standards

1.4 Objective of Project 6

1.5 Scope of Project 6

1.6 Organization of the Thesis 6

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2 Literature Review 8

2.1 Radio Wave Propagation 8

2.1.1 Propagation in Free Space 8

2.1.1.1 Free Space Propagation Loss 9

2.1.2 Line of Sight 10

2.1.3 Reflection 11

2.1.3.1 Propagation over Plane Reflecting Surface 12

2.1.4 Diffraction 14

2.1.4.1 Diffraction over Terrain Obstacles 15

2.1.5 Refraction 17

2.1.6 Multipath Fading 18

2.1.6.1 Frequency Selective Fading 19

2.1.6.2 Time selective Fading 19

2.1.6.3 Raleigh Fading 21

2.1.6.4 Rician Fading 21

2.3 Propagation Modeling 22

2.3.1 Wireless LAN Networks Design: Site Survey

or Propagation modeling 22

2.3.2 A new 3D Indoor Ray- Tracing Propagation

Model with Particular Reference to the Prediction

of Power and Delay Spread 27

3 RAY TRACING SIMULATION 32

3.1 Introduction 32

3.2 Vertical-Plane-Launch Method 33

3.3 Algorithm of Simulation Software 34

3.4 Database for Simulation 37

3.4.1 Database building 37

3.4.2 Receiver Database 39

3.4.3 Building Interior Database Format 40

3.5 Simulation Command Input 42

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3.6 Output of the Prediction Tool 42

3.7 AirMagnet Software 44

3.8 Conclusion 44

4 RESULTS AND ANALYSIS 45

4.1 Introduction 45

4.2 Output Result from VPL Software 45

4.2.1 Power and Delay Spread Output 46

4.2.2 Impulse Response Output 46

4.2.3 Ray paths information output 47

4.3 Result from AirMagnet 49

4.4 Result Visualization 50

4.4.1 Ray path visualization for Mobile Lab 51

4.4.2 Ray path visualization for Mobile Lab,

simulation Lab and corridor 54

4.5 Analysis 57

4.5.1 Fading and Multipath Effects 57

4.5.2 Comparison between Prediction and

Measurement Result 57

5 CONCLUSION AND FUTURE WORK 58

5.1 Conclusion 58

5.2 Future work 59

REFERENCES 60

APPENDICES A-C 62-114

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LIST OF TABLES

TABLE NO. TITLE PAGE

1.1 Comparison of WLAN technologies 5

2.1 One slope model empirical parameter 24

3.1 Command input simulation 43

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LIST OF FIGURES

FIGURE NO. TITLE PAGE

1.1 WLAN configurations with access point 2

1.2 Frequency band for IEEE 802.11 5

2.1 Maximum unobstructed view of the transmitting antenna

due to the curvature of a smooth earth 10

2.2 Reflection when it strike object 11

2.3 Direct and indirect paths on a flat-terrain environment 12

2.4 Diffraction when strike obstacle 14

2.5 The Fresnel zone 15

2.6 Knife edge 15

2.7 Path loss due to knife-edge diffraction 16

2.8 Refraction when strike different medium 17

2.9 Mulitpath fading 18

2.10 Doppler shift 20

2.11 Coverage prediction by a deterministic model 23

2.12 Coverage prediction by a deterministic model 23

2.13 Measured signal level 24

2.14 Prediction error (difference between 1SM prediction and

measurement) for n = 1.4 24

2.15 Multi-Wall Model geometry 25

2.16 Multi-Wall Model coverage prediction 25

2.17 MWM prediction error - difference between MWM

prediction and measurement 26

2.18 Multi-Wall Model prediction compared to measurement 26

2.19 3D extension for the indoor environment 28

2.20 Three Dimensional horizontal and vertical analysis 29

2.21 Indoor environment 30

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2.22 Average received power along the route 31

2.23 Received rms delay spread along the route 31

3.1 Ray generation in horizontal plane (Liang and Bertoni 1998) 34

3.2 Flow chart of ray-tracing simulation based on the VPL

method (Liang and Bertoni 1998) 35

3.3 Methodology process 36

3.4 Building map of WCC 38

3.5 Example of database building 38

3.6 Receiver Map 39

3.7 Database of receivers 40

3.8 Interior building database 41

3.9 Airmagnet Software with Laptop 44

4.1 Example of power and delay spread output 47

4.2 Example of impulse response output 48

4.3 Example of ray path information output 48

4.4 Example of AirMagnet measurement 49

4.5 VPL ray tracing visualization using Matlab 50

4.6(a) Ray paths visualization for all receivers 1 to 10 in 2D 51

4.6(b) Ray paths visualization for all receivers 1 to 10 in 3D 51

4.6(c) Ray paths visualization for all receivers 1 to 30 in 2D when

use two model ray 52

4.6(d) Ray paths visualization for all receivers 1 to 30 in 3D when

use two model ray 52

4.6(e) Time delay spread for Mobile Lab room 53

4.6(f) Comparison between Simulation and Measurement Loss

for Mobile Lab room 53

4.7(a) Ray paths visualization for all receivers 1 to 30 in 2D 54

4.7(b) Ray paths visualization for all receivers 1 to 30 in 3D 54

4.7(c) Ray paths visualization for receiver 29 in 2D 55

4.7(d) Ray paths visualization for receiver 29 in 3D 55

4.7 (e) Time delay spread for Mobile Lab, simulation Lab room

and corridor 56

4.7(f) Comparison between Simulation and Measurement

Loss for Mobile Lab, simulation Lab room and corridor 56

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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

λ - Wavelength

C - Velocity of light

dB - Decibels

θ - Incidence angle

f - Frequency

ht - High of receiver antenna

hr - High of transmitter antenna

A - Attenuation factor

ρ - Ground reflection coefficient

r1, r2 - Phase path distance along

h - Fresnel zone radius to the knife edge

oλ - Free space wavelength

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d∆ - Distance difference

1d - Distance from transmitter to obstacle

2d - Distance from transmitter to obstacle

τ - 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

nτ - Arrival time

nϑ - Arrival phase

iE - Received field amplitude

oE - Transmitting field strength

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LIST OF APPENDICES

APPENDIX TITLE PAGE

A Ray Tracing Propagation Prediction 62

A.1 Simulation Command Input 62

A.2 Database for simulation 67

A.2.1 Building Database for Lab Room ( bd1.txt) 67

A 2.2 Receiver Database for Lab Room (rx1.txt) 68

A.2.3 Output Prediction File for Lab Room (b1.txt) 69

A.3.1 Building Database for Lab Room and Area Around (bd2.txt) 70

A.3.2 Receiver Database for Lab Room and Area Around (rx2.txt) 72

A.3.3 Building interior Database for Lab Room and

area around (rx2.txt) 72

A3.4 Output Prediction File for Lab Room and Area around (b2.txt) 73

B AirMagnet software 74

B.1 Manual AirMagnet software 74

B.2 Output Result from AirMagnet Software 83

C Visualization Code using Matlab 96

C.1 VPL Ray Tracing Visualization Code of Lab Room

and area around 96

C.2 VPL Ray Tracing Visualization Code of Lab Room 101

C.3 Loss Result File 105

C.4 Delay Spread file 107

C.5 Ray path visualization for Mobile Lab 109

C.6 Ray path visualization for Mobile Lab, simulation Lab

and corridor 112

CHAPTER 1

INTRODUCTION

1.1 Overview

The past decade has witnessed a phenomenal growth in wireless

communication. Indoor wireless communication such as personal communication

(PCs) and wireless local area networks (LAN) are exploding rapidly. The need for an

efficient way to evaluate and tracing radio propagation in building is increasing. It is

also critical to fiend method for provide beast coverage, consequently we fiend that

the ray-tracing technique has been the beast to predict radio propagation in indoor

environments.

1.2 Problem Statement

Now days , he use of indoor wireless LAN in offices increasing .The signal

strength of these systems became wake due to placement of walls, window, glasses,

overlapping channels, interference , etc. This is important to conduct studies

research to improve coverage.

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1.3 Wireless LAN

1.3.1 Introduction

Recently wireless local area networks (WLANs) have emerged as flexible

communication systems, which have been implemented as an extension or

alternation for a wired LAN within buildings. Using electromagnetic waves WLANs

transmit and receive data over air interface, minimizing need for wired connection,

thereby it enables user mobility in covered area without losing connectivity to the

backbone net. The system implementations vary from simple peer-to-peer connection

between two computers to cover entire buildings by many transmitter/receiver

devices - access points (AP), which are connected to the wired network as in

Figure 1.1 [1].

1.3.2 Wireless LAN Standards

Tow standards bodies, IEEE ad European Telecommunications Standards

Institute (ETSI) and one technology alliance (homeRF) promote WLAN standards.

IN the IEEE 802.11family of WLANs, three standards deserve individual attention,

and a handful of others are worth a quick mention. The leasing standard is 802.11 b ,

or Wi-Fi, short for Wireless Fidelity, The cleat challenger is 802.11a, which provides

Figure 1.1: WLAN configurations with access point

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increased throughput at a higher, less cluttered frequency; the outside contender is

802.11g, which just completed the final stage of IEEE approval at the time of writing

.other WLAN standards that are worth consideration are HIPERLAN/1 and

HIPERLAN/2.

1.3.2.1 802.11 standards

The IEEE 802.11 standard specification was approved in July 1997, making it

the first wireless LAN standard to be defined. It used the same switching protocols

wired Ethernet, but allows communication to happen without wires, instead using

unlicensed 2.4GHz frequency radio communication .Two frequency modulation

techniques are supported in 802.11 FHSS and DSSS. 802.11 predicts are not

commonly sold anymore, as updated versions (802.11a and 802.11b) have take its

place, providing higher bandwidths at a lower cost.

802.11b standard is the most popular standard in the 802.11x family. The

specification was approved at the same time as 802.11 in 1999, but since then has

achieved broad market acceptance for wireless networking. 802.11b is based on the

direct sequence spread spectrum (DSSS) is easier to implement than orthogonal

frequency division multiplexing (OFDM) as used in 802 .11a , 802.11b products

came to market much sooner than their 802.11a counterparts. In addition, the

2.4GHz spectrum is available globally for WLAN configurations. While the 5GHz

spectrum that 802.11a uses is for limited uses in many countries.

802.11b standard is able to reach a maximum capacity of 11 Mbps. This

surpassed the 10 Mbps speed that is part of the original Ethernet standard, making

802.11b a practical alternative to, or extension of, a wired LAN. The use of his

2.4GHz band for communication has advantages and disadvantages. The 2.4GHz

signals are able to penetrate physical barriers. Such as walls and ceilings more

effectively than higher frequencies can. The downside of using the 2.4GHz spectrum

is congestion. Since it is unlicensed, meaning anyone can use it without obtaining a

special license; other electronic products also use this frequency for communication.

In typical indoor office configurations, an 802.11b access can communicate with

4

devices up to 100 meters (around 300 feet) away. The further away a terminal is

from the access point, the slower the communication will be devices within about 30

meters can usually achieve a data transfer rate of 111 Mbps ; beyond 30 meters, the

rate drops to 5.5Mbps,and then to 2 Mbps around 65 meters away, and finally , to 1

Mbps around the outer edge. These numbers represent the anticipated coverage area

and transmission speeds, but the products from each vendor will differ in

performance.

802.11a standard is a high speed alternative to 802.11bstandard, transmitting

at 5GHz and speeds up go 54Mbps. The move to the 5GHz band and OFDM

modulation provides two important benefits over 802.11b. First, it increases the

maximum speed per channel from11Mbps to 54Mbps.this is a tremendous boost,

especially considering that the bandwidth is shared among all the user on an access

point. The increased speed is especially useful for wireless multimedia, large file

transfers, and fast internet access. Second, the bandwidth available in the 5GHz

range is larger than available at 2.4GHz, allowing for more simultaneous users

without potential conflicts. Additionally, the 5GHz band is not as congested at the

2.4GHz band, resulting in less interference.

IEEE 802.11g standard brings high speed wireless communication to the

2.4GHz band, while maintaining backward compatibility with 802.11b. This

accomplished on two layers. First, 802.11g operates on the same 2.4GHz frequency

band as 892.11b, with DSSS modulation types for speeds up to 11 Mbps .For

54Mbps; 802.11g uses the more efficient OFDM modulation types, still within the

2.4GHz band.

Other 802.11 Standards Just as 802.11g improved upon 802.11b, other 802.11

task groups are in place to improve upon the exiting 802.11x standards. His areas of

concentration are security, quality of service, compliance and interoperability. All of

these are still in the task group stage of the specification process:

IEEE 802.11e standard, aimed at providing quality of service (QoS)

capabilities to enable reliable voice communication to complement 802.11b

systems.802.11e will also provide enhanced security and authentication mechanisms.

5

IEEE 802.11f standard aimed at developing the recommended practices for an Inter-

Access Point Protocol to achieve MultiFinder access point interoperability.

IEEE 802.11h standard, aimed at enhancing the 802.11 a High-Speed

Physical layer in the 5GHz band to make IEEE 802.11a products compliant with

European regulatory requirements.

Table1.1 and the figure2.2 below provide an overview of the characteristic and

frequencies that use in IEEE 802.11.

Short Wave Radio FM Broadcast

ExtremelyLow

Very Low

Low Medium High VeryHigh

UltraHigh

SuperHigh

Infrared Visible Light

Ultra-violet

X-Rays

Audio AM Broadcast Television Infrared wireless LAN

902 - 928 MHz (802.11) 26 MHz

ISM Band

Cellular (840MHz) NPCS

2.4 - 2.4835 GHz(IEEE 802.11b)

ISM Band

5 GHz UNII Band (IEEE 802.11a)

HyperLAN HyperLAN2

Figure 1.2: Frequency band for IEEE 802.11

802.11 802.11b 802.11a

Approved July 1997 September 1999 September 1999

Bandwidth (MHz)

83.5 83.5 300

Frequency Band (GHz)

2.4-2.835 2.4-2.835 5.15-5.25, 5.25-5.35, 5.725-5.825

Number of Non-Overlapping Channels

3 (Indoor/Outdoor)

3 (Indoor/Outdoor)

4 (Indoor) 4 (Indoor/Outdoor) 4 (Indoor/Outdoor)

Data Rate (Mbps) 1,2 1,2,5.5,11 6,9,12,18,24,36,48,54

Table1.1: Comparison of WLAN technologies

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1.4 Objective of Project

To study indoor wireless local area network (WLAN) signal propagation within

Wireless Communications Center (WCC) building, in order to obtain the best

efficiency and coverage and compare with prediction.

1.5 Scope of Project

To provide proper study of WLAN propagation signal within WCC building

of University Technology Malaysia in which tracing signal and visualizing them are

needed .The prediction area will be within room and corridor which tracing signal

that transmitting for access point to receivers inside the lab room and the per diction

will be done at a carrier frequency 2.4 GHz based on IEEE 802.11 b/g standard.

Present simulation results into three dimensional using Matlab software for

visualization while measurement part will use AirMagent software.

1.6 Organization of the Thesis

Chapter 1 contains overview about project and method that will be used in this

project, problem statement is presented factor that effect wireless LAN, wireless

LAN presented IEEE 802.11standard and frequency that used in wireless LAN

objective and scope for this project.

The literature review is performed in chapter 2. Some introduction of

propagation paths and mobile radio propagation mechanism are introduced such as

reflection, refraction, diffraction, delay spread and multipath fading, the last part

shows some prediction and propagation model.

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Chapter 3 contains the methodology process by; showing up the detailed

diagram of the project methodology and highlights briefly the steps have been taken

meet the objectives of this project.

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

Visualization Code and result in 3D 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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REFERENCES

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6. http://www.ycars.org/EFRA/Module%20C/EMInteract.htm

7. Linux Wireless LAN Howto - jt@hpl.hp.com

8. http://www.tpub.com/content/neets/14182/css/14182_72.htm for refraction

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12. http://www.airmagnet.com/products/laptop.htm

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