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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