THESIS_Salih Yanbastioglu(IUS)

A THESIS SUBMITTED TO
THE GRADUATE SCHOOL OF ENGINEERING AND NATURAL SCIENCES
OF
INTERNATIONAL UNIVERSITY OF SARAJEVO
ANALYSIS OF PERFORMANCES OF DIFFERENT SERVICES
IN WIRELESS NETWORKS
BY
SALIH YANBASTIOGLU
(1210033)
IN PARTIAL FULFILLMENT OF REQUIREMENTS
FOR
THE DEGREE OF BACHELOR OF SCIENCE
IN
ELECTRICAL AND ELECTRONICS ENGINEERING
SARAJEVO, JUNE 2013

Approval of the Faculty of Engineering and Natural Sciences
________________________
Dean ( Prof. Dr. Fehim FINDIK)
We certify that this thesis satisfies all the requirements as a thesis for the degree of Bachelor
_______________________
Head of Program (Asist. Professor Dr. Emir Karamehmedovic)
This is to certify that we have read this thesis and that in our opinion it is fully adequate, in scope
and quality, as a thesis for the degree of Bachelor of Engineering
_______________________
Supervisor (Asist. Professor Dr. Emir Karamehmedovic)
_______________________
Co-Supervisor (Senior Assistant Indira Muhic)
Examining Committee Members (first name belongs to the chairperson of the jury and the second
name belongs to supervisor)
_____________________________
_____________________________
_____________________________
Date:

iii
I hereby declare that all information in this document has been obtained and
presented in accordance with academic rules and ethical conduct. I also declare that,
as required by these rules and conduct, I have fully cited and referenced all material
and results that are not original to this work.
Name, Last name : Salih YANBASTIOGLU
Signature :

iv
ABSTRACT
ANALYSIS OF PERFORMANCE FOR WIRELESS
NETWORKS
YANBASTIOGLU, Salih
B.Sc., Department of Electrical and Electronics Engineering
Supervisor: Asist. Professor Dr. Emir Karamehmedovic
Co-supervisor: Senior Assistant Indira Muhic
June 2013, 80 pages
In this thesis are examined the performances of wireless networking standards for
different applications. Applications of different wireless standards are examined through
different requirements, regarding different and specific data types. In order to achieve this,
sample network structure is established, different standards are involved and at the end
performances different data types are compared. In deep, different standards of wireless
computer networks are modeled with OPNET simulation program.
In the second chapter, the OSI (Open System Interconnection - Open System Architecture)
application model is explained, general networking concepts are introduced, which is used
in the wireless communication standards used in order, from simple to complex
modulation techniques, supported architectures, protocols and sets of frame structures were
investigated.
In the third chapter, mentioned about quality of service (QoS) parameters for the wireless
networks.
In the fourth chapter, different standards of wireless computer networks are modeled with
OPNET simulation program. Also main characteristic and performances for different types
of traffic and applications are investigated.
In the last chapter inculdes overall conclusion related to all chapters.
Keywords: Wireless Network, IEEE 802.11x, QoS, OPNET.

v
ACKNOWLEDGMENTS
First of all, I would like to thank Professor Dr. Emir KARAMEHMEDOVIC for his
all supports in departmant. Besides, I would like to thank my adviser Indira MUHIC for
her support and guidance. Without her I could not have written this thesis. I am also
indebted to Professor Dr. Hakan KAPTAN from Marmara University for his guidance and
wisdom about OPNET in deep detail.
My non-academic thanks go to my family and my friends for making my years in
International University of Sarajevo tolerable.

6
TABLE OF CONTENTS
ABSTRACT ........................................................................................................................................4
ACKNOWLEDGMENTS..................................................................................................................5
TABLE OF CONTENTS...................................................................................................................6
CHAPTER 1 .......................................................................................................................................8
INTRODUCTION..............................................................................................................................8
AIM OF THESIS..............................................................................................................................10
CHAPTER 2 .....................................................................................................................................11
WIRELESS COMPUTER NETWORKS.......................................................................................11
2.1. THE CONCEPT OF COMPUTER NETWORKS..........................................................................11
2.1.1. OSI Reference Model................................................................................................12
2.1.2. Physical Network Topologies...................................................................................15
2.1.3. Communication Mode ..............................................................................................17
2.1.4. Access Methode........................................................................................................18
2.1.5. The ISM Bands .........................................................................................................19
2.1.6. Spread Spectrum ......................................................................................................21
2.2. WIRELESS TECHNOLOGIES (IEEE 802 STANDARDS)..........................................................24
2.2.1. WPAN.......................................................................................................................25
2.2.2. WLAN .......................................................................................................................26
2.2.2.1. IEEE 802.11 Protocol Architecture .............................................................................................27
2.2.2.2. 802.11 Architecture ......................................................................................................................34
2.2.3. WMAN ......................................................................................................................35
2.2.4. WWAN ......................................................................................................................36
CHAPTER 3 .....................................................................................................................................38
QUALITY OF SERVICE (QOS) PARAMETERS .......................................................................38
3.1. QUALITY OF SERVICES IN WIRELESS NETWORKS ..............................................................38
3.2. QUALITY OF SERVICES (QOS) PARAMETERS......................................................................39
3.2.1. Delay ........................................................................................................................39
3.2.2. Jitter .........................................................................................................................40
3.2.3. Packet Loss...............................................................................................................40
3.2.4. Throughput...............................................................................................................41
3.2.5. Bit Error Rate (BER)................................................................................................41

7
CHAPTER 4 .....................................................................................................................................42
COMPARISON OF THE PERFORMANCE OF WIRELESS NETWORKS SIMULATION
METHOD..........................................................................................................................................42
5.1. ABOUT OF SIMULATION PROGRAM ....................................................................................42
4.2. SIMULATION ENVIRONMENT..............................................................................................42
5.2.1. OPNET Tools ...........................................................................................................42
5.2.2. The Modeler Workflow.............................................................................................44
4.3. MODELLING OF THE TOPOLOGIES AND SIMULATION RESULTS ..........................................47
5.3.1. Scenario 1.................................................................................................................47
5.3.2. Scenario 2.................................................................................................................56
5.3.3. Scenario 3.................................................................................................................63
CHAPTER 5 .....................................................................................................................................71
CONCLUSION.................................................................................................................................71
5.1. CONCLUSION .....................................................................................................................71
LIST OF TABLES............................................................................................................................74
LIST OF GRAPHS...........................................................................................................................74
LIST OF FIGURES..........................................................................................................................75
LIST OF ABBREVIATIONS..........................................................................................................76
REFERENCE ...................................................................................................................................78

8
CHAPTER 1
INTRODUCTION
One or more computers and peripherals connected to each other in order to discover other
network devices form computer network. Computer networks offer an environment that
users can make sharing information and data between computers. The main purpose of
computer networks for connected users is to provide and to reach resources and to have
contact with other users.
Through the use of computer networks people save time and resources. Users can access
each other's hard disks and data, software or hardware through share options. Shared
peripherals (printer, scanner, CD-ROM, modems, etc.) can be used by all computers on the
same network.
With the spread of internet on worldwide in all areas, the internet has become a need.
Data traffic, as well as requirements of multimedia applications, such as transfer between
different concepts of speed and quality of service become very importante.
Dynamic business life in the intensive tempo, resource sharing without being tied to an
office or people, led to the need to benefit from services such as Internet access. Despite
the use of Ethernet in broad application areas, wireless LAN technology has started to
become increasingly common at offices, airports, and other public areas.
Usage of wireless network systems is through enterprise applications such as Health,
Education, Manufacturing and Service sectors.
In the field of health in order to facilitate patient, follow-up patients is used for ensuring
their access to information anytime and anywhere in hospitals. The patient bedside or
bracelet-like device information can be transmitted wirelessly to the desired location. In
some hospitals are installed for physician practices wireless controlled robot. In this way,
the doctor can make remote consultation with the patient.
In the field of education, teachers and students are provided with access in order to ensure
access to the internet in any place in the campus such as dormitories, libraries and cafes.

9
Production facilities, Home apliences, automobile and other manufacturing plants are used
in wireless computer networks. In addition, wireless control devices are used in control
systems.
The service sector, in daily life especially in the restaurant and retail stores have become
used in the wireless communication. Restaurants; orders, fast tracking, large warehouses
and stores, merchandise offers tremendous ease of monitoring of inputs and outputs.
Today, free wireless access points are set up and people from the train stations, hotels,
airports, can provide internet access at these places.
There are many different standards for wireless LAN systems. Different protocols and
physical infrastructure should be used in different frequency bands. Using the different
frequencies and standards gives better results depending on the distance, needs and
purpose of use. Developing new technologies, developing with each other and complement
each other rather than to replace. Diversity of existing wireless applications is inevitable.
Due to this diversity, publication of standards resulting confusion is prevented.
Worldwide, the establishment of standards for the purpose of conducting studies in various
organizations. These organizations provides information and classifies technology related
to in many areas such as introduction of systems, equipment compatibility approvals,
access areas, should be provided services, security policies.
WLAN standardization activities, the IEEE (Institute of Electrical and Electronics
Engineers-Institute of Electrical and Electronics Engineers), ETSI (European
telecomunications Institute - European Telecommunications Institute), MMAC
(Multimedia Mobile Access Communication-Multi-Media Mobile Communication) is
carried out by the three main organizations.
Practices and standards developed tremendously raises some problems in practice.
Difficult to determine and implement the most appropriate standard and there are
compliance issues arising from the use of a combination of different standards.
During the preparation of the application of a network there are certain criteria that should
be considered. As an example of these criteria, the data type of the application to be

10
moved, the service will be provided the number of users, the physical dimensions of the
field.
AIM OF THESIS
In this thesis are examined the performances of wireless networking standards for different
applications. Applications of different wireless standards are examined through different
requirements, regarding different and specific data types. In order to achieve this, sample
network structure is established, different standards are involved and at the end
performances different data types are compared. In deep, different standards of wireless
computer networks are modeled with OPNET simulation program.
In the second chapter, the OSI (Open System Interconnection - Open System Architecture)
application model is explained, general networking concepts are introduced, which is used
in the wireless communication standards used in order, from simple to complex
modulation techniques, supported architectures, protocols and sets of frame structures
were investigated.
In the third chapter, mentioned about quality of service (QoS) parameters for the wireless
networks.
In the fourth chapter, different standards of wireless computer networks are modeled with
OPNET simulation program. Also main characteristic and performances for different types
of traffic and applications are investigated.
In the last chapter inculdes overall conclusion related to all chapters.

11
CHAPTER 2
BACKGROUND
WIRELESS COMPUTER NETWORKS
A computer networks consists of computers with various features and these
computers connecting each other via physical transmission media, communication
and media devices, and the rule sets (protocols). Physical transmission, traditionally
provided by the cable connections. In cases where it is not possible or disadvantages
of cable connection, wireless networks have been preferred.
Nowadays, wireless computer networks have been seeing in all areas where cables
are not required or wiring is difficult and costly. Wireless Applications are being
used efficiently for connecting peripherals to computers or smart phones and mobile
computers or devices include a local area network.
In this section, by giving the general concepts of networking and there are mentioned
the importance of these wireless computer networks. Explained the concepts and
standards used in wireless computer networks.
2.1.The Concept of Computer Networks
In the Network, each computer and peripheral are called the node, computers with
shared resources on a network is called the server.
Mutual availability of computers on the network to transfer data, the signs used
between the transmitter and receiver to work together, to harmonize data formats and
data evaluation methods, a set of rules called protocols. Protocol, all devices on the
network would be communicating with each other determines how.
Network topology is the arrangement of the various elements such as links,nodes and
so on of a computer or biological network. Essentially, it is the topological structure
of a network, and may be depicted physically or logically. Physical topology refers to
the placement of the network's various components, including device location and
cable installation, while logical topology how data flows within a network, regardless
of its physical design. Distances between nodes, physical interconnections,

12
transmission rates, and/or signal types may differ between two networks, yet their
topologies may be identical. [2]
2.1.1. OSI Reference Model
The Open Systems Interconnection (OSI) model is a reference tool for understanding
data communications between any two networked systems. The ISO (International
Organization for Standardization) standard 7498-1 defined this model. This model
allows all network elements to operate together, no matter who created the protocols
and what computer vendor supports them. [1]
The OSI model is a seven-layer structure that specifies the requirements for
communications between two computers. Each layer both performs specific
functions to support the layers above it and offers services to the layers below it. The
three lowest layers focus on passing traffic through the network to an end system.
The top four layers come into play in the end system to complete the process.
Figure 1 OSI Reference Model [5]
A networking model offers a generic means to separate computer networking
functions into multiple layers. Such a model of layered functionality is also called a
“protocol stack” or “protocol suite”. Protocols or rules, can do their work in either
hardware or software or, as with most protocol stacks, in a combination of the two.
The nature of these stacks is that the lower layers do their work in hardware or
firmware (software that runs on specific hardware chips) while the higher layers
work in software.

13
Layer 1: The Physical Layer
The physical layer of the OSI model defines connector and interface specifications,
as well as the medium (cable) requirements. The NIC cards in your PC and the
interfaces on your routers all run at this level since, eventually, they have to pass
strings of ones and zeros down the wire.
In a LAN environment, Category 5e UTP (Unshielded Twisted Pair) cable is
generally used for the physical layer for individual device connections. Fiber optic
cabling is often used for the physical layer in a vertical or riser backbone link. The
IEEE, EIA/TIA, ANSI, and other similar standards bodies developed standards for
this layer. [3]
Layer 2: The Data Link Layer
Data Link Layer defines the access strategy for sharing the physical medium,
including data link and media access issues. Protocols such as PPP, SLIP and HDLC
live here. On an Ethernet, of course, access is governed by a device’s MAC address,
the six-byte number that is unique to each NIC. Devices which depend on this level
include bridges and switches, which learn which segment’s devices are on by
learning the MAC addresses of devices attached to various ports.
This is how bridges are eventually able to segment off a large network, only
forwarding packets between ports if two devices on separate segments need to
communicate. Switches quickly learn a topology map of the network, and can thus
switch packets between communicating devices very quickly. It is for this reason that
migrating a device between different switch ports can cause the device to lose
network connectivity for a while, until the switch, or bridge, re-ARPs (see box on
ARP).. A switch uses this address to filter and forward traffic, helping relieve
congestion and collisions on a network segment. [2] NICs have two parts these are
MAC and LLC.
a)Logic Link Control(LLC)
Allows communication with the upper layers. Access to information from source and
destination layers of network protocols during packaging inserts.

14
b)Media Access Control (MAC)
Addressing the converted frame structure using the system allows you to get the
information to the other side. Enter the computer's network environment, the system
is well organized.
Layer 3: The Network Layer
The network layer of the OSI model, provides an end-to-end logical addressing
system so that a packet of data can be routed across several layer 2 networks
(Ethernet, Token Ring, Frame Relay, etc.). To make it easier to manage the network
and control the flow of packets, many organizations separate their network layer
addressing into smaller parts known as subnets. Routers use the network or subnet
portion of the IP addressing to route traffic between different networks. Each router
must be configured specifically for the networks or subnets that will be connected to
its interfaces.
Routers communicate with one another using routing protocols, such as Routing
Information Protocol (RIP) and Open version of Shortest Path First (OSPF), to learn
of other networks that are present and to calculate the best way to reach each network
based on a variety of criteria (such as the path with the fewest routers).
Routers and other networked systems make these routing decisions at the network
layer. The network layer accomplishes this via a process known as fragmentation. A
router’s network layer is usually responsible for doing the fragmentation. All
reassembly of fragmented packets happens at the network layer of the final
destination system. Some basic security functionality can also be set up by filtering
traffic using layer 3 addressing on routers or other similar devices. [1]
Layer 4: The Transport Layer
The transport layer of the OSI model, offers end-to-end communication between end
devices through a network. Depending on the application, the transport layer either
offers reliable, connection-oriented or connectionless, best-effort communications.
The most common transport layer protocols are the connection-oriented TCP
Transmission Control Protocol (TCP) and the connectionless UDP User Datagram
Protocol (UDP). TCP over IP, since Layer 4 is above (over) Layer 3. It is at this layer

15
that, should a packet fail to arrive (perhaps due to misrouting, or because it was
dropped by a busy router), it will be re-transmitted, when the sending party fails to
receive an acknowledgement from the device with which it is communicating. The
more powerful routing protocols also operate here. OSPF and BGP, for example, are
implemented as protocols directly over IP. [3]
Layer 5: The Session Layer
The session layer, provides various services, including tracking the number of bytes
that each end of the session has acknowledged receiving from the other end of the
session. This session layer allows applications functioning on devices to establish,
manage, and terminate a dialog through a network.
The Session Layer is very important in the E-commerce field since, once a user starts
buying items and filling their “shopping basket” on a Web server, it is very important
that they are not load-balanced across different servers in a server pool.[3]
Layer 6: The Presentation Layer
The presentation layer, is responsible for how an application formats the data to be
sent out onto the network. The presentation layer basically allows an application to
read (or understand) the message. Protocol conversions, encryption/decryption and
graphics expansion all takes place here. [3]
Layer 7: The Application Layer
The application layer, provides an interface for the end user operating a device
connected to a network. This layer is what the user sees, in terms of loading an
application (such as Web browser or e-mail); that is, this application layer is the data
the user views while using these applications. [1]
2.1.2. Physical Network Topologies
Physical topology is about the layout of computers in a network. How computers are
wired and how computers are connected to each other determines the physical
topology. [4] There are six physical network topologies these are; bus, ring, star,
mesh, tree, mesh.

16
Data Bus Topology
In data bus topology computers are connected to each other through a straight line, it
is the simplest connection method. A simple scheme of data bus network topology
can be seen in Figure 2.
Figure 2 : Data Bus Topology [5]
Star Topology
In this topology there is a device like a hub or switch at the center of the network. [6]
The computers that are going to be the part of the network are connected with UTP
(Unshielded Twisted Pair) and STP (Shielded Twisted Pair) cables with RJ-45
connectors to a hub or a switch. Star topology can be seen in Figure 3 [5].
Figure 3 : Star Topology[5]
Ring Topology
In ring topology as is in data bus topology there is no need to make termination, as is
also understood from its name computers are connected in ring shape. Ring topology
is also imaginable as data bus topology which two end of the backbone is connected
to each other. Each computer is connected with the previous and the next computer
[6]. Ring topology is displayed in Figure 4.
Figure 4 : Ring Topology[5]
Like in data bus topology if there is a problem in one node of the ring data transfer in
the whole network will be interrupted.[5]

17
Tree Topology
Tree topology is firmed by adding star shaped stations onto the backbone of the data
bus topology. With this aspect tree topology accommodates all the features of data
bus and star topology. As it is seen from Figure 5 it is exactly like a tree, in this
figure the branches of this tree represents networks that has different topologies and
different networks are connected to each other with tree trunk [6].
Figure 5 : Tree Topology
.
Mesh Topology
In this topology all computers are connected to the other computers with separate
cables. As it is seen in Figure 6 there is no meaningful shape like star, ring or tree
topology. Mesh topology is only used in special cases with low number of
computers, because with the increase of the number of computers the number of
cables will increase incrementally.[6] Each device has dedicated connection to all
other devices on network. In Figure 7, Mesh internetwork has multiple paths between
two destinations using redundant routers.
Figure 6 : Mesh Topology Figure 7 : Mesh Topology 2
2.1.3. Communication Mode
Communication between two devices can be simplex or duplex.
Simplex: In simplex communication, the data flow is one way, data can be
transmitted from the sender to the receiver only. As given example of simplex
communication is TV and Radio broadcast.
Half-Dublex: Only one device can communicate at a time. Two-way data
transmission that is not simultaneous.

18
Full-Dublex: Each device has a separate communication channel.Two-way,
simultaneous data transmission.
2.1.4. Access Methode
Since the medium on a network is shared, when two computers send data at the same
time, a data collision would occur, destroying both data.[13]
Figure 8 : Data Collision
Access methods are designed to ensure that data can be sent successfully over the
shared medium. These methods include CSMA/CD and CSMA/CA.
CSMA/CD
CSMA/CD stands for Carrier Sense Multiple Access with Collision Detection. When
a computer wants to send data, it would listen to the channel. If the channel is free, it
would send the data. After the data is sent, the computer would listen to the channel
again to see whether a collision occurs or not. If there is a collision, it would wait a
random period of time before attempting to re-send the data. A random period is
necessary, otherwise, the cycle “wait-send-collide” would occur repeatedly.
CSMA/CD is the most popular access method and is used by Ethernet networks.
CSMA/CA
CSMA/CA stands for Carrier Sense Multiple Access with Collision Avoidance. The
computer ready to send a data listens to the channel. If the channel is free, it would
send an “intend-to-send” signal and listen to see if another computer has also sent the
“intend-to send” signal. [13]
If it receives an “intend-to-send” signal from another computer, it would wait a
random period of time, and repeat the above process until the channel is absolutely
free. Then, it sends the data.
CSMA/CA is commonly used by wireless LAN where collisions cannot be detected.

19
2.1.5. The ISM Bands
In 1985 the Federal Communications Commission issued rules permitting
“intentional radiators” to use the “ Industrial, Scientific and Medical (ISM) Bands
(902-928, 2400-2483.5, 5725-5850 Mhz) at power levels of up to one Watt without
end-user licenses. Originally these bands had been reserved for unwanted, but
unavoidable emissions from industrial and other processes, but they also supported a
few ( often military) communications users.
Figure 9 : Frequency Bands
The new rules led to the development of a large number of consumer and
professional products and is considered to be an important step towards the
development of wireless computing or multimedia applications.
Applications in the ISM band include, wireless LANs, short range links for advanced
traveller systems ( electronic toll collection), garage door openers, home audio
distribution, cordless phones, private point to point links, remote control, wireless
telemetric systems ( e.g electrical power consumption monitoring) etc. Applications
seem to be limited by the imagination rather than technology. A drawback of the
ISM band is lack of any protection against interference. In particular microwave
ovens limit the useful range of such communications devices. [14]
Unlicensed Band Frequency Total Bandwidth Common Uses
Industrial, Scientific and
Medical (ISM)
902-928 MHz
2.4-4835 GHz
5.725-5.85 GHz
234.5 MHz Cordless phones,WLANs,
wireless public branch exchanges
Unlicensed Personal
Communications Systems
1910-1930 MHz
2390-2400 MHz
30 MHz WLANs, wireless public branch
exchanges
Unlicensed National
Information Infra-structure
(U-NII)
5.15-5.25 GHz
5.25-5.35 GHz
5.725-5.825 GHz
300 MHz WLANs, wireless public branch
exchanges, campus applications,
long outdoor links
Millimeter Wave 59-64 GHz 5 GHz Home networking applications
Table 1 : Unregulated (Unlicensed) Bands

20
Why use the 2.4 or 5.8 GHz bands if a signal in the 900 MHz band goes farther and
is better at penetrating solid objects?
The reason is that more data can be sent faster in the higher frequencies. Which band
is best depends on the application. A wireless link sending network data needs as
much bandwidth as possible. On the other hand, a wireless signal controlling a pump
two miles away has to contend more with the challenges of distance than the speed or
the amount of data being sent. The choice of which band to use is not determined by
the user. Public wireless standards specify the frequency band to be used. The band
for a proprietary device is selected by the manufacturer for the intended application.
A key difference between the 2.4 and 5.8 GHz bands is channel allocation. When
used for Wi-Fi, the bands are segmented into sections called channels. In the 2.4
GHz band there are 11 channels available for use in the U.S. Of the 11, only three do
not overlap. Communications on overlapping channels can interfere with one another
and diminish performance of wireless transmissions. The 5.8 GHz band has eight
channels. None overlap. The 5.8 GHz band offers the flexibility of having multiple
networks that do not interfere with each other. However, there is greater attenuation
in the 5.8 GHz band, resulting in potentially shorter transmission distances than in
the 2.4 GHz band.
As stated previously, the 2.4 GHz band generally is allocated for license-free
transmissions throughout the world. Many wireless devices operate in this band. In
addition to wireless standards such as Ethernet and Bluetooth, many cordless phones
and even microwave ovens operate in the 2.4 GHz band. As a result, congestion
could be a potential issue for new or future installations. Regardless of the source,
high concentrations of RF energy translate into possible interference for wireless
devices. Different wireless technologies deal with interference in different ways.
Knowing how the different wireless “engines” work is useful in understanding why
different wireless technologies perform differently, and why one technology may be
better than another for a given application.[15]

21
2.1.6. Spread Spectrum
License-free wireless transmissions in the ISM bands require the use of one of the
spread spectrum technologies. Spread spectrum refers to a method of transmitting a
signal by “spreading” it over a broad range of frequencies, much wider than the
minimum bandwidth needed to transmit. The benefits of spread spectrum technology
are:
 Increased transmission speed for faster throughput.
 Operation of multiple networks in the same area for greater flexibility in
system layout and expansion.
 Minimized impact on performance due to interference.
 Reduced power consumption for battery- or solar-powered installations.
Three wireless technologies come under the spread spectrum umbrella. [15]
Table 2 : Spread Spectrum
OFDM
Orthogonal frequency division multiplexing (OFDM) is a type of multicarrier
modulation. OFDM uses overlapped orthogonal signals to divide a frequency-
selective channel into a number of narrowband flat-fading channels. Instead of
transmitting the data symbols sequentially at a high symbol rate on a single carrier, a
block of symbols is encoded using the Fast Fourier Transform (FFT), and transmitted
in parallel over a number of subchannels. The subchannels are spaced by the inverse
of the symbol time, so making them orthogonal. Individual subchannels will have a
symbol period longer than the multipath delay spread, and so OFDM is useful for
avoiding multipath interference. If a particular subchannel has high noise or
interference, then it can be deactivated, so reducing the effects of fading and
interference.
Spread
Spectrum
OFDM
(Orthogonal Frequency
Division Multiplexing)
FHSS
(Frequency-
Hopping Spread
Spectrum)
DSSS
(Direct-Sequence
Spread Spectrum).

22
Figure 10 : Typical 802.11 OFDM channel showing subcarriers and spectral mask [20]
OFDM technology is still under development, and there are a number of problems to
be solved. Firstly, the guard bands and cyclic prefix reduce data throughput.
Frequency offsets between transmitter and receiver must be removed with automatic
frequency control (AFC), otherwise the subcarriers will no longer be orthogonal.
Synchronization of multicarrier schemes is more difficult than single carrier because
there may be hundreds of samples per multicarrier symbol. Finally, because there are
a large number of subcarriers, the combined signal has a very large peak-to-average
power ratio (PAPR), and to maintain linearity over this range, the power amplifier
(PA) requires back-off by as much as 10dB.
OFDM is very attractive for mobile radio transmission where multipath interference
is severe. It is shown in that the BER performance of an OFDM system is very
similar to that of a single-carrier system. OFDM performance can be improved
through the use of channel coding and PAPR reduction techniques (although this
introduces more complexity).[16] In the Table 3, advantages and disadvantages of
Orthogonal Frequency Division Multiplexing.
OFDM
Advantages Disadvantages
Mitigates multipath High complexity and deployment costs
Guard bands reduce efficiency
Frequency offsets require accurate AFC
Synchronization is difficult
High peak-to-average power ratio
requires PA back-off
Table 3 : Advantages and Disadvantages of OFDM

23
FHSS
Frequency-hopping spread spectrum systems place data in a narrow band but
modulate that carrier frequency in a defined pattern often referred to as a code or
hopping sequence . In order to make rapid and frequent changes to the carrier
frequency, both the transmitting and receiving device must share the same code and
be designed for rapid frequency changes. The transmitted signal is left unaltered
other than to change the carrier frequency.
Figure 11 : FHSS Frequency Band [20]
By changing the carrier frequency, interference is averaged between channels instead
of directly affecting one channel more than any other. FHSS systems are very
common in military applications where a high immunity to signal jamming in
required. [18] In the Table 4, advantages and disadvantages of Frequency Hopping
Spread Spectrum.
FHSS
Simple frequency planning Low bit rates
Good interference rejection
Low-power, low-cost radios
Table 4 : Advantages and Disadvantages of FHSS
DSSS
In contrast, Direct-sequence spread spectrum systems spread the information signal
or baseband signal about a fixed frequency carrier signal which has much wider
bandwidth than the original signal. This is accomplished by taking the exclusive
disjunction or XOR of the original signal with the spreading code. The transmitted
DSSS waveform is usually spread across such a large frequency range that the
resulting waveform is not distinguishable from the surrounding ambient noise.
Encapsulating data in a wide frequency band also allows for narrow band
interference to be easily rejected.[18] However, if the interference is at a high energy
level, DSSS systems will completely fail.[19]

24
Figure 12 : DSSS Frequency Band [20]
Lastly, since DSSS systems broadcast low amounts of energy over a wide range, they
work better in situations where there are many users sharing the same portion of the
spectrum. In the Table 5, advantages and disadvantages of Direct Sequence Spread
Spectrum.
DSSS
Simple frequency planning Medium bit rates (up to 11Mbps)
Good interference rejection
Very low access delay
Table 5 : Advantages and Disadvantages of DSSS
2.2.Wireless Technologies (IEEE 802 Standards)
A wireless network enables people to communicate and access applications and
information without wires. This provides freedom of movement and the ability to
extend applications to different parts of a building, city, or nearly anywhere in the
world. Wireless networks use either radio waves or infrared light for communication
between users, servers, and databases. This type of communication is invisible to the
human eye. In addition, the actual medium (air) is transparent to the user. There are
four types of wireless topologies.
Figure 13 : Wireless Technologies
Wireles
Technologies
WPAN WLAN WMAN WWAN
Bluetooth
802.15.1
Home
RF
WIFI
802.11
HiperLAN
I/II ETSI
WLL
802.16
GSM
2G
GPRS
EDGE
2.5G
WiMAX
802.16
HiperMAN UMTS
3G

25
2.2.1. WPAN
Wireless personal area networks (WPANs) are used to convey information over short
distances among a private, intimate group of participant devices. Unlike a wireless
local area network (WLAN), a connection made through a WPAN involves little or
no infrastructure or direct connectivity to the world outside the link. This allows
small, power-efficient, inexpensive solutions to be implemented for a wide range of
devices [23]
Figure 14 : ISM Bands for WPAN [24]
The main WPAN technology is Bluetooth, launched by Ericsson in 1994, which
offers a maximum throughput of 1 Mbps over a maximum range of about thirty
metres. Bluetooth, also known as IEEE 802.15.1, has the advantage of being very
energy-efficient, which makes it particularly well-suited to use in small devices.
HomeRF (for Home Radio Frequency), launched in 1998 by HomeRF Working
Group (which includes the manufacturers Compaq, HP, Intel, Siemens, Motorola and
Microsoft, among others) has a maximum throughput of 10 Mbps with a range of
about 50 to 100 metres without an amplifier. The HomeRF standard, despite Intel's
support, was abandoned in January 2003, largely because processor manufacturers
had started to support on-board Wi-Fi (via Centrino technology, which included a
microprocessor and a Wi-Fi adapter on a single component).
The technology ZigBee (also known as IEEE 802.15.4) can be used to connect
devices wirelessly at a very low cost and with little energy consumption, which
makes it particularly well-suited for being directly integrated into small electronic
appliances (like home appliances, stereos, and toys). Zigbee, which operates on the
frequency band of 2.4 GHz and on 16 channels, can reach transfer speeds of up to
250 Kbps with a maximum range of about 100 metres.

26
Figure 15 : WPAN[23]
Infrared connections can be used to create wireless connections over a few metres,
with speeds than can reach a few megabits per second. This technology is widely
used in home electronics (like remote controls), but light waves can interfere with the
signal. irDA (Infrared Data Association), formed in 1995, has more than 150
members.
Finally, Ultra-Wideband (UWB) wireless is a rapidly growing technology that
promises to revolutionize low power, short-range wireless applications. UWB has
quickly emerged as the leading technology for applications like wireless Universal
Serial Bus (USB) and short-range ground penetrating radars. UWB radios differ from
conventional narrow-band radios, with a variety of specialized test demands.
2.2.2. WLAN
In the last few years a new type of local area network has appeared. This new type of
LAN, which is the wireless LAN, provides an alternative to the traditional LANs
based on twisted pair, coaxial cable, and optical fiber. The wireless LAN serves the
same purpose as that of a wired or optical LAN: to convey information among the
devices attached to the LAN. But with the lack of physical cabling to tie down the
location of a node on a network, the network can be much more flexible moving a
wireless node is easy. As opposed to the large amount of labor required to add or
move the cabling in any other type of network. Also going wireless may be a better
choice where the physical makeup of the building makes it difficult or impossible to
run wire in the building. [23]

27
Figure 16 : WLAN[21]
Wireless networks are ideal for portable computers. Using wireless connections
allows portable computers to still be portable without sacrificing the advantages of
being connected to a network. These machines can be setup virtually anywhere
within the building. Wireless networks can be used in combination with cabled
LANs. In that all the machines that will require relative mobility will be connected
wirelessly, while the stations that are for the most part permanant can be connected
through cable.[21]
2.2.2.1. IEEE 802.11 Protocol Architecture
The 802.11 standards are a group of evolving specifications defined by the Institute
of Electrical and Electronic Engineers (IEEE). Commonly referred to as Wi‐Fi the
802.11 standards define a through‐the‐air interface between a wireless client and a
base station access point or between two or more wireless clients. There are many
other standards defined by the IEEE. These standards are a set of specifications that
all manufacturers must follow in order for their products to be compatible. This is
important to insure interoperability between devices in the market. Standards may
provide some optional requirements that individual manufacturers may or may not
implement in their products.
The physical layer defines the frequency band, data rate, and other details of the
actual radio transmission.In the Table 6 shows, IEEE 802.11 standards.

28
802.11 802.11a 802.11b 802.11g
Available
Bandwidth
83.5 MHz 300 MHz 83.5 MHz 83.5 MHz
Unlicensed
frequency of
operation
2.4-2.4835 GHz
DSS, FHSS
5.15-5.35 GHz
5.725-5.825 GHz
OFDM
2.4-2.4835 GHz
DSSS
2.4-2.4835 GHz
DSSS, OFDM
Number of non-
overlapping
channels
3(indoor/outdoor) 4(indoor/outdoor) 3(indoor/outdoor) 3 (indoor/outdoor)
Data rate per
channel
1,2 Mbps
6,9,12,18,24,
36,48,54 Mbps
1,2,5.5,11 Mbps
1,2,5.5,6,9,12,18,
24,36,48,54 Mbps
Compatibility 802.11 Wi-Fi5 Wi-Fi
Wi-Fi at 11 Mbps
and below
Table 6: IEEE 802.11 Standard
802.11a
Ratification of 802.11a took place in 1999. The 802.11a standard uses the 5 GHz
spectrum and has a maximum theoretical 54 Mbps data rate. 802.11a was the first
standard aimed at enterprise-class wireless LAN technology, offering many
advantages over previous options. At speeds of up to 54 Mbps, 802.11a provides
higher throughput over the entire coverage area. The 5 GHz band that 802.11a
operates in is not highly populated, so there is less congestion to cause interference
or signal contention. 802.11a is a reliable and efficient medium for accommodating
high-bandwidth applications for numerous users.
Devices utilizing 802.11a are required to support speeds of 6, 12, and 24 Mbps.
Optional speeds go up to 54 Mbps and include 48, 36, 18 and 9 Mbps throughput
rates. These differences are the result of implementing different modulation
techniques. As an 802.11a client device travels farther from its Access Point (AP),
the connection remains intact but speed decreases or “falls back.” [28]
Pros: Fast maximum speed and regulated frequencies prevent interference from
other devices.
Cons: Higher cost, shorter range and a signal that is easily obstructed.
802.11b
The IEEE established 802.11b in 1999 to improve the data rate of the original 802.11
standard – definingrates up to 11 Mbps. 802.11b devices suffer from interference
from other products operating in the 2.4 GHz band. Devices operating in the 2.4 GHz

29
range include microwave ovens, Bluetooth® devices, baby monitors and cordless
telephones.
IEEE 802.11b is an extension of the IEEE 802.11 DSSS scheme, providing data rates
of 5.5 and 11 Mbps. Each channel requires the same 11-MHz bandwidth as an
802.11 DSSS channel. To achieve a higher data rate in the same bandwidth, the
standard employs a modulation schemecalled complementary code keying. IEEE
802.11b is currently the most commonly used 802.11 standard in commercial
products.[28]
Pros: Low cost, good signal range.
Cons: Slowest maximum speed, interference with other home appliances on the
unregulated frequency band.
802.11g
In 2003, the IEEE ratified the 802.11g standard with a maximum theoretical data rate
of 54 megabits per second (Mbps) in the 2.4 GHz ISM band. As signal strength
weakens due to increased distance, attenuation (signal loss) through obstacles or high
noise in the frequency band, the data rate automatically adjusts to lower rates
(54/48/36/24/12/9/6 Mbps) to maintain the connection. When both 802.11b and
802.11g clients are connected to an 802.11g router, the 802.11g clients will have a
lower data rate. Many routers provide the option of allowing mixed 802.11b/g clients
or they may be set to either 802.11b or 802.11g clients only.
802.11g works in the 2.4 GHz band (like 802.11b), but additionally includes the
same OFDM based transmission scheme as 802.11a. It operates at a maximum
physical layer bit rate of 54 Mbit/s, exclusive of forward error correction codes,
providing about 22 Mbit/s average user-level data throughput. 802.11g hardware is
fully backwards compatible with 802.11b hardware.
To illustrate 54 Mbps, if you have DSL or cable modem service, the data rate offered
typically falls from 768 Kbps (less than 1 Mbps) to 6 Mbps. Thus 802.11g offers an
attractive data rate for the majority of users. The 802.11g standard is backwards
compatible with the 802.11b standard. Today 802.11g is still the most commonly
deployed standard.
Pros: Fast maximum speed, good signal range and is not easily obstructed.

30
Cons: More expensive than 802.11b and home appliances may interfere with this
unregulated frequency. [30]
802.11n
In January, 2004 the IEEE 802.11 task group initiated work. The goal of 802.11n is
to significantly increase the data throughput rate. While there are a number of
technical changes, one important change is the addition of multiple‐input
multiple‐output (MIMO) and spatial multiplexing. Multiple antennas are used in
MIMO, which use multiple radios and thus more electrical power.
802.11n will operate on both 2.4 GHz (802.11b) and 5 GHz (802.11a) bands. This
will require significant site planning when installing 802.11n devices. The 802.11n
specifications provide both 20 MHz and 40 MHz channel options versus 20 MHz
channels in 802.11a and 802.11b/g standards. By bonding two adjacent 20 MHz
channels, 802.11n can provide double the data rate in utilization of 40 MHz
channels. However, 40 MHz in the 2.4 GHz band will result in interference and is
not recommended nor likely which inhibits data throughput in the 2.4 GHz band. It is
recommended to use 20 MHz channels in the 2.4 GHz spectrum like 802.11b/g
utilizes. For best results of 802.11n, the 5 GHz spectrum will be the best option.
Deployment of 802.11n will take some planning effort in frequency and channel
selection. Some 5 GHz channels must have dynamic frequency selection (DFS)
technology implemented in order to utilize those particular channels.
Another consideration of 802.11n is the significantly increased electrical power
demand in comparison to the current 802.11b/g or 802.11a products. This is
primarily due to multiple transmitters.
The Wi‐Fi Alliance is testing and certifying compatibility of 802.11n radio draft 2.0
specifications. There are several realities to consider. They are only testing against
some basic criteria and interoperability points. Also the number of devices being
tested against each other is low. This certification does not provide any protection
against changes to the 802.11n standard prior to ratification.
802.11n is a recent amendment that improves upon the previous 802.11 standards by
adding multiple-input multiple-output antennas (MIMO) and many other newer

31
features. Two-stream (or two antenna) MIMO defines data rates up to 300 Mbps,
three-stream up to 450 Mbps and four-stream up to 600 Mbps.
Pros: Fastest maximum speed, best signal integrity, resistant to signal interference
from outside sources.
Cons: More expensive than 802.11g and use of multiple channels may interfere with
other 802.11 b/g networks.
Other IEEE 802.11 standards
The standards discussed so far provide specific physical layer functionality, but
several other 802.11 standards are in place or in development, as Table 7 shows.
IEEE 802.11c covers bridge operation. A bridge is a device that links to LANs with a
similar or identical MAC protocol. It performs functions similar to those of an
Internet Protocol (IP)-level router, but at the MAC layer. Typically, a bridge is
simpler and more efficient than an IP router.
In 2003, the 802.11c task group completed its work on this standard, which folded
into the IEEE 802.1d standard for LAN bridges. IEEE 802.11d is a regulatory
domain update. It covers issues related to regulatory differences in various countries.
IEEE 802.11e revises the MAC layer to improve QoS and address MAC
enhancement. It accommodates time scheduled and polled communication during
null periods when no other data is moving through the system.
Standard Data issued Scope
802.11c 2003 Bridge operation at 802.11 MAC layer
802.11d 2001
Physical layer:Extend operation of 802.11 WLANs to new regulatory
domains
802.11e Ongoing MAC: Enhance to improve QoS and security mechanisms
802.11f 2003 Recommended practices for multivendor access point interoperability
802.11h 2003
Physical or MAC: Enhance IEEE 802.11a to add indoor and outdoor
channel selection and improve spectrum and transmit power
management
802.11i Ongoing MAC: Enhance security and authentication mechanisms
802.11j Ongoing Physical: Enhance IEEE 802.11a to conform to Japanese requirements
802.11k Ongoing
Radio resource measurement enhancements to provide interface to
higher layers for radio and network meausurement
802.11m Ongoing
Maintenance of IEEE 802.11-1999 standard with technical and
editional corrections
802.11n Ongoing Physical or MAC: Enhancements to enable higher throughput.
Table 7 : Other IEEE 802.11 standards. [28]

32
In addition, IEEE 802.11e improves polling efficiency and channel robustness. These
enhancements should provide the quality necessary for services such as IP telephony
and video streaming. A QoS station is any base station implementing 802.11e.
IEEE 802.11f addresses interoperability among access points from multiple vendors.
In addition to providing communication among WLAN stations in its area, an access
point can function as a bridge that connects two 802.11 LANs across another type of
network, such as an Ethernet LAN or a wide area network. So IEEE 802.11f
facilitates the roaming of a device from one access point to another while ensuring
transmission continuity. IEEE 802.11h covers spectrum and power management. The
objective is to make 802.11a products compliant with European regulator
requirements.
The European Union military uses part of the 5-GHz band for satellite
communications. The standard includes a dynamic channel selection mechanism to
prevent selection of the frequency band’s restricted portion. The standard’s transmit-
power-control features adjust power to EU requirements. IEEE 802.11i defines
security and authentication mechanisms at the MAC layer. This standard addresses
security deficiencies in the Wired Equivalent Privacy (WEP) algorithm originally
designed for the MAC layer of 802.11. The 802.11i scheme’s stronger encryption
and other enhancements improve security. IEEE 802.11j addresses 4.9- and 5-GHz
operation in Japan. IEEE 802.11k defines enhancements that provide mechanisms
available to protocol layers above the physical layer for radio resource measurement.
The standard specifies what information should be available to facilitate the
management and maintenance of wireless and mobile LANs, including the
following:
 To improve roaming decisions, an access point can provide a site report to a
mobile device when the Access point determines that the mobile device is
moving away from it. The site report lists access points—from best to worst
service—that a mobile device can use in changing over to another access
point.

33
 An access point can collect channel information from each mobile device on
the WLAN. Each mobile device provides a noise histogram that displays all
non-802.11 energy on that channel as perceived by the mobile device. The
access point also collects statistics on how long a channel is in active use
during a given time. This data enable the access point to regulate access to a
given channel.
 Access points can query mobile devices to collect statistics, such as retries,
packets transmitted, and packets received. This gives the access point a more
complete view of network performance.
 802.11k extends the transmit-power-control procedures (defined in 802.11h)
to other regulatory domains and frequency bands, to reduce interference and
power consumption, and to provide range control.
IEEE 802.11m is an ongoing task group activity to correct editorial and technical
issues in the 802.11 standard. The other task groups generate documents, and the
802.11m task group reviews those documents to locate and correct inconsistencies
and errors in the 802.11 standard and its approved amendments. The IEEE 802.11n
task group is studying various enhancements to the physical and MAC layers to
improve throughput. These enhancements include such items as multiple antennas,
smart antennas, changes to signal encoding schemes, and changes to MAC protocols.
The task group’s current objective is a data rate of at least 100 Mbps, as measured at
the interface between the 802.11 MAC layer and higher layers. The motivation for
measuring at the upper interface to the MAC layer is that a user can experience a
data rate significantly less than that of the physical layer. Overhead includes packet
preambles, acknowledgments, contention windows, and various interface spacing
parameters. The result is that the data rate coming out of the MAC layer could be
about one-half of the physical-layer data rate. In addition to improving throughput,
802.11n addresses other performance- related requirements, including improved
range at existing throughputs, increased resistance to interference, and more uniform
coverage within an area.[28]

34
2.2.2.2. 802.11 Architecture
The 802.11 specification defines two types of operational modes: ad hoc (peer-to-
peer) mode and infrastructure mode.
In ad hoc mode, the wireless network is relatively simple and consists of 802.11
network interface cards (NICs). The networked computers communicate directly
with one another without the use of an access point.
In infrastructure mode, the wireless network is composed of a wireless access
point(s) and 802.11 network interface cards (NICs). The access point acts as a base
station in an 802.11 network and all communications from all of the wireless clients
go through the access point. The access point also provides for increased wireless
range, growth of the number of wireless users, and additional network security.
Ad Hoc Mode
In ad hoc mode, also known as Independent Basic Service Set (IBSS) or peer-to-
peer mode, all of the computers and workstations connected with a wireless NIC card
can communicate with each other via radio waves without an access point. Ad hoc
mode is convenient for quickly setting up a wireless network in a meeting room,
hotel conference center, or anywhere else sufficient wired infrastructure does not
exist. [31]
Infrastructure Mode
In infrastructure mode, all mobile and wireless client devices and computers
communicate with the access point, which provides the connection from the wireless
radio frequency world to the hard-wired LAN world. The access point performs the
conversion of 802.11 packets to 802.3 Ethernet LAN packets. Data packets traveling
from the LAN to a wireless client are converted by the access point into radio signals
and transmitted out into the environment. All wireless clients and devices within
range can receive the packets, but only those clients with the appropriate destination
address will receive and process the packets. A basic wireless infrastructure with a
single access point is called a Basic Service Set (BSS). When more than one access
point is connected to a network to form a single sub-network, it is called an Extended
Service Set (ESS).

35
Figure 17: Ad-Hoc Mode[31] Figure 18: BSS and ESS [31]
The 802.11 specification includes roaming capabilities that allow a client computer
to roam among multiple access points on different channels. Thus, roaming client
computers with weak signals can associate themselves with other access points with
stronger signals. Alternately, by setting up multiple access points to cover the same
geographic area and by client workstation networking loads can be better balanced.
A wireless LAN NIC may decide to “reassociate” itself with another access point
within range because the load on its current access point is too high for optimal
performance. These capabilities can have a positive impact on overall network
performance [31]
2.2.3. WMAN
Fast communications of network within the vicinity of a metropolitan area is called
WMAN, that put up an entire city or other related geographic area and can span up to
50km. WMAN designed for a larger geographical area than a LAN. The standard of
MAN is DQDB which cover up to 30 miles with the speed of 34 Mbit/s to 155
Mbit/s.1t is more common in schools, colleges, and public services support a high-
speed network backbone. WMAN is a certified name by the IEEE 802.16 that
functioning on Broadband for its wireless metropolitan. WMAN have air interface
and a single-carrier scheme intended to activate in the 10-66 GHz spectrum, supports
incessantly unreliable transfer levels at many certified frequencies.

36
Figure 19 : WMAN[22]
WMAN opens the door for the creation and Provide high-speed Internet access to
business subscribers.It can handle thousands of user stations with prevents collisions
and support legacy voice systems, voice over IP, TCP/IP. WMAN offer different
applications with different QoS requirements. The technology of WMAN consist of
ATM, FDDI, and SMDS. WiMAX is a term used for Wireless metropolitan area
network and plinth on the IEEE 802.16. [22]
2.2.4. WWAN
A wireless wide area network (Wireless WAN), covers a much more extensive area
than wireless LANs. Coverage is generally offered on a nationwide level with
wireless network infrastructure provided by a wireless service carrier (for a monthly
usage fee, similar to a cellular phone subscription). While wireless LANs are used to
allow network users to be mobile within a small fixed area, wireless WANs are used
to give Internet connectivity over a much broader coverage area, for mobile users
such as business travellers or field service technicians.
Wireless WANs allow users to have access to the Internet, e-mail, and corporate
applications and information even while away from their office. Wireless WANs use
cellular networks for data transmission and examples of the cellular systems that are
used are: CDMA, GSM, GPRS, and CDPD. A portable computer with a wireless
WAN modem connects to a base station on the wireless networks via radio waves.
The radio tower then carries the signal to a mobile switching center, where the data is
passed on to the appropriate network. Using the wireless service provider’s
connection to the Internet, data communications are established to an organization’s
existing network. Wireless WANs use existing cellular telephone networks, so there

37
is also the option of making voice calls over a wireless WAN. Both cellular
telephones and wireless WAN PC Cards have the ability to make voice calls as well
as pass data traffic on wireless WAN networks.[27]
Figure 20 : WWAN[27]
Wide Area Network connectivity is often necessary and nearly always expensive.
Broadband is recognised as the low cost solution but often does not provide the
required bandwidth. Many organisations therefore install wired leased lines, and
because of the cost, have to compromise on bandwidth. Siracom offers a variety of
wireless solutions offering more bandwidth for less money and eliminating recurring
revenue costs. Unlicensed 5GHz point to point and point to multi-point solutions
from Proxim are suitable replacements for 100Mb/s full duplex lines and support
distances upto 20 Miles. Unlicensed 60GHz and 80GHz solutions from Bridgewave
replace full duplex gigabit solutions operating at this speed at distances of five
miles.[27] In most cases full line of sight or near line of sight is required.

38
CHAPTER 3
QUALITY OF SERVICE (QoS) PARAMETERS
3.1.Quality of Services in Wireless Networks
‘Quality of Service(QoS) is defined as the ability of the network to provide a service
at an assured service level’.[42]
QoS is the ability to provide a level of assurance for data delivery over the network.
For example, traffic of different classes or traffic with different requirements
receives differen levels of QoS assurance. Therefore, the term QoS support
mechanism to refer to any mechanism that is equipped by any kind of QoS support.
The term QoS guarantee will be referred to a mechanism that can provide guaranteed
support. The objectives of QoS provision can be categorized into:
 Prioritized QoS Support
 Parameterized QoS Support
Prioritized QoS support aims at providing different level of QoS support for
different classes of traffic, e.g. , high priority traffic receives better throughput and
delay than low priority class traffic. Prioritized QoS support is also known as
differentiated QoS support.
Parameterized QoS support aims at providing a specific level of QoS support, e.g.,
at least 64 Kbps and delay less than 30 ms,on average. Parameterized QoS support is
also known as specific QoS support. Under prioritized QoS support, scheduling
mechanisms classify packets into different priority classes. Under parameterized
QoS support, scheduling mechanisms consider the requirement of a particular packet
and provide the appropriate treatment.
The wireless communication was originally developed for army use, because of its
ease of mobility , installation and flexibility; later on it was made available to
civilian use also. With the increasing demand and penetration of wireless services,

39
users of wireless network now expect QoS and performance comparable to what is
available from fixed networks.[42]
3.2.Quality of Services (QoS) Parameters
To provide and sustain QoS, resource management must be QoS-driven. To allocate
resources, the resource management system must consider different parameters:
 Resource availability;
 Resource control policies, including Service Level Agreements(SLA);
 QoS requirements of applications, whichare quantified by QoS
parameters(e.g. Jitter, Delay, Packet Loss),
To keep tracj if the contracted QoS are being met, the QoS parameters must be
monitored and resources reallocated in response to system anomalies. Application
layer must ensure that the required QoS parameters can be satisfied(through QoS
negotiation signaling) prior to the reservation of resources. If negotiation is agreed,
the session starts. If a change of state happens i.e. degradation in the QoS, and the
resource manager cannot make resource adjustment to compensate, the application
can either adapt to new level of QoS or degrade to a reduced level of service. The
measurement of QoS is based on parameters like delay, jiter, packet loss, throughput
and many others, depending on the application and management scheme.
3.2.1. Delay
Delay is intrinsic to communications, since the end points are distant and the
information will consume some time to reach the other side. Delay is also referred as
to latency. Delay time can be increased if the if packets face long queues in the
network (congestion), or crosses a less direct route to avoid congestion. The delay
can be measured either one-way (the total time from the source that sends a packet to
destination that will receive it), or round-trip (the one-way latency from source to
destination plus the one-way latency from the destination back to source). Round-trip
delay is used frequently, because it can be meaused from a single point using the
‘Ping’ command. The round trip delay is a relatively accurate way of measureing
delay, because it excludes the amount of time that a destination system spends
proccessing the packet. The ‘Ping’ command performs no packet processing. It only

40
sends a response back when it receives a packet. In the case for having a more
accurate delay measure, then it is needed the measure in both points of the network.
The final result is the minimum delay time possible in that link for sending a packet
from a source to the destination. [45]
3.2.2. Jitter
Jitte is the delay variation and is introduced by the variable transmission of delay of
the packets over network. Thiscan occur because of routers’ internal queues behavior
in certain circumstances (e.g. flow congestion), rouring changes, etc. This parameter
can seriously affect the quality of steaming audio and/or video. To handle jitter, it is
needed to collect packets and hold them long enough until the slowest packets arrive
in time, rearranging them to be played in the correct sequence. Jitter buffers can be
observing when using video or audio streaming websites(e.g. YouTube) and are used
to counter jitter introduced by the internet so that a continuous playout of the media
transmitted over the network can be possible. When clicking in a link to play the
video, buffering starts before the media stream actually does. This procedue causes
additional delay, but is necessary in case of jitter sensitive applications.[45]
3.2.3. Packet Loss
Packet loss happens when one or more packets of data being transported acress the
internet or a computer network fail to reach their destination. Wireless and IP
networks cannot provide a guarantee that packets will be delivered at all, and will fail
to deliver (drop) some packets if they arrive when their buffers are already full. This
loss of packets can be caused by other factors like signal degradation, high loads on
network links, packets that are corrupted being discarded or defect in network
elements.
Wireless networks have higher probability of loss that is introduced by the air
interface (e.g. interference caused by other systems, multiple obstacles (buildings,
environment) in the path, multipath fading, etc. ). Some transport protocols such as
Transfer Control Protocol (TCP) make delivery control by receiving
acknowledgments of packet receipt from the receiver. If packets are lost during

41
transfer. TCP will automatically resend the segments which were not acknowledged
at the cost of decreasing the overall throughput of the connection.
3.2.4. Throughput
Throughput is the amount of data which a network or entity sends or receives data, or
the amount of data processed in one determined time space. It has as basic units of
measures the bits per second (bit/s or bps). The throughput can be lower of the
channel capacity of a communications link. A good example of throughput measure
is performed by a bandwidth meter (which is used for measuring the real transfer rate
that a DSL connection has). The bandwidth Meter estimates the current throughput
of a DSL connection by calculating the rate at which a test file is delivered to the
computer for a particular Server. Paying for a 1000 kbps in the means that the
bandwidth available for this connection is up to this 1000kbps in the access network.
A bandwidth meter tool reliably measures the speed with which a user can download
information from particular servers. However, it may not reflect users’ experience
downloading particular pages on the Internet. There are many factors which affect
the rate at which webpages and files download, regardless of connection type.[45]
These factors include:
 The load on the servera a user is accessing.
 The remote server’s ‘distance’ from the measured system (in terms of
network hops (routers)).
 The speed of the computer.
 The number of programs running on the computer.
 The configuration of the network.
3.2.5. Bit Error Rate (BER)
Bit Error Rate testing is one way to measure the performance of a communications
system. The standard equation for a bit error rate measurement is: Common
measurement points are bit error rates of: BER = Errors / Total Number of Bits

42
CHAPTER 4
COMPARISON OF THE PERFORMANCE OF WIRELESS
NETWORKS SIMULATION METHOD
In this section, applications of wireless local area networks of different standards and
different forms of the various connections are modeled with the help of a simulation
program performance is compared with the services. Network modeling systems is usually
carried out by subtracting the analytical mathematical model. However, the simulation
method is used for the mathematical model of complex systems that are difficult to
remove.
4.1.About of Simulation Program
OPNET (IT Guru Academic Edition 9.1) is used to design and study sommunication
networks, devices, protocols and applications. It providedes a graphical editor interface to
build models for various network entities from physical layer modulator to application
processes [41]
IT Guru Academic Edition limitations:
 Limited import and export capabilities
 Limited wireless functionality
 Other product modules are not supported
 The maximum number of simulation events is limited by 50 million
 The maximum number of intermediate nodes is limited by 20
4.2.Simulation Environment
4.2.1. OPNET Tools
OPNET supports model specification with a number of tools, called editors. These editors
handle the required modeling information in a manner that issimilar to the structure of real
network systems. Therefore, themodel-specification editors are organized hierarchically.
Model specifications performed in the Project Editors are used to define various
datamodels, new links and nodes, etc. This organization isdescribed below. [41]

43
Project Editor
Project Editor is used to develop network models. Network models are made up of subnets
and node models. This editor also includes basic simulation and analysis capabilities. The
Project Editor is the main staging area for creating a network simulation. From this editor,
you can build a network model using models from the standard library, choose statistics
about the network, run a simulation and view the results.It is also possible to create node
and process models, build packet formats, and create filters and parameters, using
specialized editors that you can access from the Project Editor. In the following Figure an
exapmle of the project editor view of a Sample Network is shown. [41]
Figure 21 : Project Editor- view of sample network
Node Editor
Node editor is used to to develop node models. Node models are objects in a network
model. They are made up of modules with process models. The Node Editors lets you
define the behavior of each network object. Behavior is defined using different modules,
each of which models some internal aspect of node behaviour such as data creation, data
storage, etc. A network object is typically made up of multiple modules that define its
behavior. In the following figure, there are some parts of a router ‘s internal structure,
such as a TCP module, an UDP module, an UDP module and an IP module and an IP
module.

44
Process Model
Process Editor is used to develop process models. Process models control module
behaviour and may reference parameter models. This editor lets you create process models,
which control the underlying fonctionality of the node models created in the Node Editor
[41]. Process models are represented by finite state machines (FSMs), and are created with
icons that represent states and lines that represent transitionsbetween states. Operations
performed in each state or for a transition are described in embedded C or C++ code
blocks.
4.2.2. The Modeler Workflow
This section outlines the workflow when using OPNET.
Figure 22 : Workflow Model [41]
Create Network Model
The first step is to create the networks model. It is necessary to generate the network to
simulate in any of the following three ways:
 Placing individual nodes from the object palette into the workspace.
 Using the rapid configuration tool.
 And/or importing the network from an external data.
Furthermore, you have to introduce the traffic you want to run through the network.
There is two main ways of putting traffic in the model:
 Importing
 Manually specifying
Choose Statistics
Afterwards and before running a simulation, it is necessary to choose the statistics we want
to collect. OPNET does not automatically collect all statistics in the system because there

45
are so many available that you may not have enough disk space to store them. Specifying
statistics is a straightforward task which is performed through the GUI [41].
Run Simulation
The third thing to set is configuring the parameters of the simulation and running them.
Running simulations is typically thought of as the next-to-last step in the simulation and
modeling process, the last step being results analysis. However, simulation is typically
done many times in the modeling process to check the rightness of the generated network.
There are different kinds of analysis that can be done in OPNET.
 Discrete Event Simulation (DES)
 Flow Analysis
 ACE QuickPredict
 Hybrid Simulation (within the DES environment)
Discrete event simulation provides the most detailed results but has tha longest running
times. This is because it does a more through analysis than the others, handling explicit
traffic, conversation pair traffic, and link loads. [41].
Flow Analysis uses analytical techniques and algorithms to model steady-state network
behavior. Flow Analysis does not model individual protocol messages or packets, therefore
it does not generate results for transient network conditions. It can be used to study routing
and reachability across the network in steady state, and in scenarios with one or more
failed devices. Execution runtimes can be significantly faster as compared with DES
ACE QuickPredict uses an analytical technique for studying the impact on application
response time of changing network parameters (e.g., bandwidth, latency, utilization, packet
loss). This technique is supported within the OPNET Application Characterization
Environment (ACE)
Hybrid simulation combines 2 distinct modeling techniques (analytical and discrete) to
provide accurate, detailed results for targeted flows.
Hybrid simulation relies on background and explicit traffic:
 Background traffic is used to represent most of a network's ambient load at an
abstract level

46
 Selected network application flows are represented in detail, using the explicit
traffic models
Execution runtimes can be signifcantly faster as compared with DES
View and Analyze Result
It is the last step of simulation. The results can be watched from the Project Editor or from
the Analysis Tool. The Analysis Tool provides the capability to extract data from
simulation output files, and to manipulate and display it according to various plotting
methodes. Data can be manipulated through built-in operations in a different way to get
wanted information.[42]
Hence, the final workflow of a project could be as follows:
 Create project
 Create baseline scenario
o Import or create topology
o Import or create traffic
o Choose results and reports to be collected
o Run the simulation
o View results and analyze them
Iterate by duplicating the scenerio and changing parameters.
OPNET uses a project and scenario approach to model networks. Project is a collection of
related network scenario in which each explores a different aspect of network design.
A project contains at least one scenario and a scenario is a single instance of network
containing all the information. It is possible to run all scenarios of the network at the same
time and compare the results of each one. This allows the scenarios to check if server will
support and increment of the traffi, the effect of the increment of the traffic in a link in the
response of a service, etc [43]
Available Analyze Statistics
To analyze the performance of the WLAN protocol, several statistics can be collected
during simulation execution. Statistics can be collected on a per-node or a per-module
basis. [44]

47
The available node statistics are:
Delay: Time it takes to successfully deliver data (including buffer delay). End-to-end delay
of all packets received by the node’s wireless LAN MAC and forwarded to the higher
layer. Time it takes to successfully deliver data (including buffer delay)
Load: Rate at which data is sent by the wireless LAN source. Total number of bits received
from the higher layer. Packets arriving from the higher layer are stored in the higher layer
queue.
Media Access Delay: Time it takes to successfully deliver a frame.Total time (in seconds)
that the packet is in the higher layer queue, from arrival to the point when it is removed
from the queue for transmission.
Throughput: Rate at which data is received by the wireless LAN destination. Throughput
is the average rate of successful bits delivery over a communication channel. The
throughput is usually measured in bits per second (bit/s or bps), and sometimes in data
packets per second or data packets per time slot. The system throughput or aggregate
throughput is the sum of the data rates that are delivered to all terminals in a network. Rate
at which data is received by the wireless LAN destination.
4.3.Modelling of the Topologies and Simulation Results
From the simulated configuration shown above it is interesting to consider following
parameters in order to show quality of service parameters. The scenario consists of a
wireless and a wireline network. The purpose of the scenario is to demonstrate the inter
communication between the wireless and wireline network through the internet backbone.
4.3.1. Scenario 1
For the choosen scenario two sites have diffeent parameters. Site 1 has data rate of 1Mbps
and site 2 has 11 Mbps. Here are supported two types of traffic http and ftp with different
data. From simulation is taken traffic as File Transfer(Light-FTP) and Web Browsing
(Light-HTTP). The site-1 and site-2 subnets each contain 20 wireless stations; all stations
comply with the wireless LAN (802.11) protocol. The clients in the Wireless LAN are
trying to communicate with servers at the remote site via IP cloud.

48
Figure 23 : WLAN-Scenario-1
On both sides, half of all workstations carry FTP traffic and the others HTTP traffic. The
Access Point nodes in site-1 and site-2 connect each subnet to the wireline network as
following two of figures. Workstations communicate with each other and with nodes
outside their LAN through the Access Point (AP).
Sites Nodes Data Rates FTP clients Traffic HTTP Clients Traffic
Office 1 Clients :FTP,HTTP 1 Mbps FileTransfer (Light) Web Browsing (Light)
Office 2 Clients :FTP,HTTP 11Mbps FileTransfer (Light) Web Browsing (Light)
Table 8: Parameters of scenario-1
Simulation Parameter
Simulation Parameter Value
Simulator
IT Guru Academic
Edition 9.1
Network type Office
Network Size 46 Nodes
Mobility Model Random way point
Traffic type HTTP, FTP
Simulation Time 1000 sec
Table 9 : Parameters of simulation 1-2

49
Figure 24 : Office Network, Site-1 Figure 25 : Office Network, Site-2
Site 1 has data rate of 1Mbps and site 2 has 11 Mbps. These data rates are modeled as the
speed of the transmitter and receiver connected to the WLAN MAC process. Each data rate
is associated with a separate channel stream, from the MAC process to the transmitter and
from the receiver to the MAC process. A station can transmit data packets only at the
configured data rate.
HTTP and FTP clients traffic received
Graph 1 : Client Traffic Received (HTTP-FTP)
It is interesting to evaluate performances of HTTP and FTP traffic, from the aspect of sent
and received traffic. Here for this cencarion received traffic for HTTP is higher from the
traffic received. This graph is related with number of packets sent. From this can be found
number of errors received in sequence.

50
HTTP and FTP clients traffic sent
Graph 2 : Client Traffic Sent (HTTP-FTP)
The results shown on the graph above clearly show the difference in sent traffic, since two
sites are configured to support different data rates.Site 1 supports data rate of 1Mbps and
site 2 supports 11 Mbps. Data are sent randomly and site with higher data rate has more
bandwith and sents more traffic.
Delay for HTTP clients and Access Points
Graph 3 : WLAN-Delay for different data rate between AP and WS (HTTP)

51
From the graph above is observed that delay is affected with different data rate and
different traffic type. Site 1 supports 1Mbps site 2 supports 11Mbps which causes higher
delay in transmission of the packets. This means that shown above is clearly seen that for
lower data rate for the same type of traffic delay will be higher compared to the
transimission on higher data rate. Also, both of access point has a different delay because
they have different data rate and they provide service for many workstations
simultaneously.
Delay for HTTP clients
Graph 4 : WLAN-Delay for different data rate (HTTP)
For HTTP traffic is choosen light version. Delay is measured between two workstation on
different sides. From the graph shown above is clearly seen that for lower data rate for the
same type of traffic delay will be higher compared to the transimission on higher data rate.

52
Delay for FTP clients and Access Point
Graph 5 : WLAN-Delay for different data rate between AP and WS (FTP)
On this graph is shown delay for FTP traffic. Light version of traffic is choosen, with
delay between access point in one network and workstation in the same network. Also here
is noticable higher delay with lower data rate.
Load for FTP clients and Access Point
Graph 6 : WLAN-Load for different data rate between AP and WS (FTP)

53
From the graph can be seen that load of the links is higher for higher bandwidth. This also
shows that between access point and workstation load is much higher since total bandwith
is shared among workstations.
Load for FTP clients
Graph 7 : WLAN- Load for different data rate (FTP)
For FTP clients, the graph is shown that load of the links is higher for higher bandwidth.
That’s means site-1 has 1 Mbps data rate so there will be observed more slowly data
stream than site-2. Also, packets arriving from the higher layer are stored in the higher
layer queue. Due to the data rate occurs more data queues. If quality of service parameters
can be designed carefully, ftp and http are used to be bandwidth more effectively by using
queuing techniques.

54
Load for HTTP clients
Graph 8 : WLAN- Load for different data rate (HTTP)
On this graph is shown load for HTTP traffic. HTTP clients are transferred bits more than
FTP. For a single shot small file, you might get it faster with FTP (unless the server is at a
long round-trip distance). When getting multiple files, HTTP should be the faster one.
There will be seen same differences between of site-1 and site-2 load because of data rate.
For HTTP, pipelining makes asking for multiple files from the same server faster. Also,
compression(automatic) makes less data for sent.

55
Throughput for FTP clients
Graph 9 : WLAN-Throughput for different data rate (FTP)
For FTP clients, the graph is shown that throughput of the links is higher for higher data
rate. As seen on graph, throughput is the average rate of successful bits delivery over a
communication channel so site-2 is more successful in delivering bits.
Throughput for HTTP clients
Graph 10 : WLAN-Throughput for different data rate (HTTP)

56
On this graph is shown througput for HTTP traffic. HTTP clients are transferred bits more
than FTP. There will be seen same differences between of site-1 and site-2 throughput
because of data rate. FTP is a two-way system as files are transferred back and forth
between server and workstation. On the other hand HTTP is a one-way system as files are
transported only from the server onto the workstation's browser. Therefore HTTP is using
bandwidth more efficintly.
4.3.2. Scenario 2
For the choosen scenario two sites have same parameters. Site 1 and site 2 have same data
rate of 11Mbps. Here are supported two types of traffic http and ftp with different data.
From simulation is taken traffic as File Transfer (Light-FTP) and Web Browsing (Light-
HTTP). The site-1 and site-2 subnets each contain 20 wireless stations; all stations comply
with the wireless LAN (802.11) protocol. The clients in the Wireless LAN are trying to
communicate with servers at the remote site via IP cloud.
Sites Nodes Data Rates FTP clients Traffic HTTP clients Traffic
Table 10: Parameters of scenario-2
This scenario has a one different thing from previous scenerio that is data rate.
HTTP and FTP clients traffic received
Graph 11 : Client Traffic Received same data rate (HTTP-FTP)

57
From the graph shown above can be noted that traffic received by client station for http is
much higher than traffice received by ftp clients. This is choosen randomly. FTP is a
protocol used to upload files from a workstation to a FTP server or download files from a
FTP server to a workstation. HTTP, is a protocol used to transfer files from a Web server
into a browser in order to view a Web page that is on the Internet. By nature it can contain
more data than FTP.
FTP file uploaded is used in cases when the file size is more than 70 MB HTTP upload is
used for smaller files.
HTTP and FTP clients traffic sent
Graph 12 : Client Traffic Sent same data rate (HTTP-FTP)
This graph is related to the graph 11, where is shown traffic received. In this case is shown
sent traffic by clients and is higher for http . But it is interesting to show number of packets
loss.

58
Delay for HTTP and FTP clients
Graph 13 : WLAN-Delay for same data rate between AP and WS (HTTP)
From the graph above is observed that delay is affected with same data rate for HTTP data
traffic. Both of sites support 11Mbps data rate. As shown above is clearly seen that for
same data rate and same type of traffic delay will be same ratio. Also, both of access point
has a approximately same delay because they have same data rate and they provide service
for many workstations simultaneously.

59
Delay for HTTP clients
Graph 14 : WLAN-Delay for same data rate (HTTP)
For HTTP traffic is choosen light version. There were only workstation’s delaying curves.
Delay is measured between two workstation on different sides. From the graph shown
above is clearly seen that for the same data rate and same type of traffic delay will be same
curves.
Delay for FTP clients
Graph 15 : WLAN-Delay for same data rate (FTP)

60
On this graph is shown delay for FTP traffic. Light version of traffic is choosen, with delay
between two site networks and workstations. As can be seen, system has a delay under the
20ms. These delays can be tolerated easly. FTP has a bi-directional file transfer system
that’s why FTP has more different delay time than HTTP.
Graph 16 : WLAN-Load for same data rate (FTP)
For FTP clients, the graph is shown that load of workstations in both of sites. There will be
observed the same data stream on each site because both of them have 11 Mbps data rate.
There are transferred data from clients to server and from server to clients that's why FTP
has less ratio of bits than HTTP.

61
Graph 17 : WLAN-Load for same data rate (HTTP)
As shown this graph, load for HTTP traffic. HTTP clients are transferred bits more than
FTP. For HTTP communication, a client can maintain a single connection to a server and
just keep using that for any amount of transfers. Although, FTP must create a new one for
each new data transfer. Repeatedly doing new connections are bad for performance due to
procedure called handshakes/connections all the time and redoing the TCP slow start
period and more.

62
Load for HTTP and FTP clients and Access Points
Graph 18 : WLAN-Load for same data rate (HTTP-FTP)
On this graph is shown load for HTTP and FTP traffic. HTTP clients are transferred bits
more than FTP. For a single shot small file, you might get it faster with FTP. When getting
multiple files, HTTP should be the faster one.
Throughput for FTP clients
Graph 19 : WLAN-Throughput for same data rate (FTP)

63
For FTP clients, the graph is shown that throughput of the links is the same for same data
rate. As seen on graph, throughput is the average rate of successful bits delivery over a
communication channel so most of them has close together.
Throughput for HTTP clients
Graph 20 : WLAN-Throughput for same data rate (HTTP)
On this graph is shown througput for HTTP traffic. HTTP clients are transferred bits more
than FTP. There will be seen same ratio between of site-1 and site-2 throughput because of
data rate. HTTP is a one-way system as files are transported only from the server onto the
workstation's browser. Therefore HTTP is using bandwidth more efficintly and transfering
more data in per second.
4.3.3. Scenario 3
For the choosen scenario four sites have diffeent parameters. Sites have as seen parameters
following on the table. Here are supported three types of traffic http, ftp and voice with
different data rate. From simulation is taken traffic as File Transfer(Heavy-FTP) , Web
Browsing (Heavy-HTTP) and Voice Traffic (G.711, G.723.1) . The office-1 and office-2
subnets each contain 3 wireless stations also each site has 1 server ; all workstations
comply with the wireless LAN (802.11) protocol. The clients in the Wireless LAN are
trying to communicate with other sites via four routed networks.

64
Figure 26 : WLAN-Scenario-3
On all of sides, each workstations carry different traffic such as FTP traffic, HTTP traffic
and Voice traffic. All office networks connected to each other with routed wired network.
The Access Point nodes in all sites connect each subnet to the wired network as following
figures. Workstations communicate with each other and with nodes outside their LAN
through the Access Point (AP).
Sites Nodes
Data
Rates
Voice
clients
FTP clients
Traffic
HTTP Clients
Traffic
Office
1
Clients :FTP,HTTP,VOICE
Server : HTTP
1 Mbps G.711
FileTransfer
(Heavy)
Web Browsing
(Heavy)
Office
2
Server : FTP
11
Mbps
G.723.1
FileTransfer
(Heavy)
Web Browsing
(Heavy)
Office
3
Clients :FTP,HTTP,VOICE 1 Mbps G.711
FileTransfer
(Heavy)
Web Browsing
(Heavy)
Office
4
11
Mbps
G.723.1
FileTransfer
(Heavy)
Web Browsing
(Heavy)
Table 11 : Parameters of scenario-3

65
Site 2 and Site 4 has 11 Mbps data rate.
Figure 27: Office Network, Site 1 Figure 28 : Office Network, Site 2
Site-1 and Site-3 has 1 Mbps data rate.
Figure 29 : Office Network, Site 3 Figure 30 : Office Network, Site 4
Simulation Parameter
Table 12: Parameters of simulation 3
Simulation Parameter Value
Simulator IT Guru Academic Edition 9.1
Network type Office
Network Size 22 Nodes
Traffic type HTTP, FTP,VOICE
Simulation Time 10 min

66
Throughput for HTTP-FTP-VOICE clients
Graph 21 : WLAN-Throughput of Office-1 for Http-Ftp-Voice Traffic
On this graph is shown througput for FTP, HTTP and VOICE traffics. Naturally, As we
have seen VOICE client is transferred bits more than FTP and HTTP. There will be seen
same differences between of other sites throughput because of data rate. In the site-1, the
Voice codec being used was G.711, which requires 64 Kbps of throughput per call so each
voice call using the G.711 codec and a 20 msec sample size requires at least 80 Kbps of
throughput. Also, as seen on graph FTP client has more stable data transfer rate because it
does only way transfer. On the other hand, HTTP client has an increasing and changing
bandwidth rate because web browser include different type of data.

67
Throughput for VOICE traffic
Graph 22 : WLAN-Throughput of Voice Traffic
For 2 different data rate and voice codec, site-4 has 11Mbps data rate and G.723.1 voice
codec therefore as can be seen that has the most efficient packet delivery success rate.
G.723.1 Voice codec has two bit rates associated with it. These are 5.3 kbps and 6.3 kbps.
The higher bit rate has greater quality. The lower bit rate gives good quality and provides
system designers with additional flexibility. Both rates are a mandatory part of the encoder
and decoder. It is possible to switch between the two rates at any 30 ms frame boundary.
Site-1 and Site-3 has 1Mbps transmission rate and there are G.711 (PCM) voice client so
as seen on graph these two sites are more inefficient.

68
Load for HTTP traffic
Graph 23 : WLAN-Load for Http Traffic
On this graph is shown load for HTTP traffic. HTTP clients are transferred bits more than
FTP. Site-1 and Site-3 also HTTP server support 1Mbps data rate so there will be
overloaded but as seen on the graph site 2 has a top level because this site 11 Mbps
transmissin rate so there will be seen more data queue.
Delay for VOICE traffic
Graph 24 : WLAN-Delay for Voice Traffic

69
From the graph above is observed that delay is affected with different voice codec and
different data rate. Site-1 supports 1Mbps site-2 and site-4 support 11Mbps which causes
higher delay in transmission of the packets. As shown above is clearly seen noticable delay
for PCM packets. Both of data rate and compression protocol affects packet transmission
time and delay.
End-to-End Delay for Voice Packet
Graph 25 : WLAN-Packet Voice End-to-End Delay
On this graph is shown packets of voice End-to-End Delay ,End-to-End delay refers to the
transmission time of a packet across a network from its source to its destination. As can be
seen the effects of different type of compression codecs on End-to-End Delay. Site-1 has
less data transmission ratio than site-4 so there are significant differences between two site.

70
Delay Variation for Voice Packet
Graph 26 : WLAN-Packet Voice Delay Variation
As shown this graph, Site-1 has the biggest packet delay variation points because this site
has 1 Mbps transmissin rate. In addition, PCM voice packet frame bigger than GSM voice
packet , so there are too much differences as seen Graph 26 . As known, Packet Delay
Variation is a measure of the difference in the End-to-End delay between packets in a flow,
ignoring any packets that have been lost. Also in OPNET, PDV corresponds to the
variance of the delay.

71
CHAPTER 5
CONCLUSION
5.1.Conclusion
Thanks to the conveniences of wireless computer networks of areas of use widespread.
However, a new and different technologies are being developed day by day. This
development has led to improve new standards for overcome of different needs. The
purpose of use, depending on the distance and needs to be moved data gives better results
than the use of different frequencies and standards. Developing new technologies,
developing with each other rather than to replace, and becoming complementary. In the
computer system used wireless communication standards: IEEE 802.11, 802.11a, 802.11b,
HiperLAN ETSI standards are used for wireless local area networks. Apart from these,
there are some kinds of standarts such as Bluetooth, ZigBee, HomeRF and so on.
In this thesis, all of these standards are classified according to application areas. For three
scenarios are simulated and analyzed by computer simulations. In third chapter, thanks to
the OPNET IT Guru Academic Edition, three different scenarios are modeled and
compared perfomance’s for different parametric value and traffics. These parametric
values are data rates such as 1Mbps and 11Mbps.
The ratio of packet transmissions at 11 Mbps and 1 Mbps are high for all congestion levels.
For high congestion points, the time to successfully transmit a small data packet sent at 1
Mbps is bigger than large data packet sent at 11 Mbps. Also, the time elapsed by packets
transmitted at 11 Mbps is just about half the time elapsed by packets transmitted at 1
Mbps. So, the number of bytes transmitted at 11 Mbps is approximately 2 or 3 times more
than at 1 Mbps.
Each site has a different data rate which causes higher delay in transmission of the packets.
This means that shown above is clearly seen graphs of delay for lower data rate for the
same type of traffic delay will be higher compared to the transimission on higher data rate.
Also, all of access point has a different delay because they have different data rate and they
provide service for many workstations simultaneously.

THESIS_Salih Yanbastioglu(IUS)

THESIS_Salih Yanbastioglu(IUS)

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