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International Journal of Engineering and Applied Sciences (IJEAS)
ISSN: 2394-3661, Volume-2, Issue-12, December 2015
27 www.ijeas.org
Abstract— The aim of this paper is to evaluate the
throughput and delay performance of IEEE802.11 WLANs
using different network performance monitoring tools. It also
shows detailed procedure on how to use these network
monitoring tools (NetStress, Wireshark and Jperf) to monitor a
real time network. The study was carried out to establish the
effects of varying the number of work stations against the
network performance in a real WLAN environment. The result
shows that maximum throughput and minimum delay can only
be achieved in the non saturated case, that is, it is dependent on
the number of active nodes.
Index Terms—WLAN, Network, Time, delay, throughput,
NetStress, Wireshark, Workstations and Jperf
I. INTRODUCTION
Managing a network without monitoring is similar to driving
a vehicle without a speedometer or a fuel gauge. Network
monitoring is the use of logging and analysis tools to
accurately determine traffic flows, utilization, and other
performance indicators on a network. Good monitoring tools
give you both hard numbers and graphical aggregate
representations of the state of the network. This helps you to
visualize precisely what is happening, so you know where
adjustments may be needed (http://wndw.net).
There are several benefits to implementing a good monitoring
system for your network:
Network budget and resources are justified. Good
monitoring tools can demonstrate without a doubt
that the network infrastructure (bandwidth,
hardware, and software) is suitable and able to
handle the requirements of network users.
Network intruders are detected and filtered. By
watching your network traffic, you can detect
attackers and prevent access to critical internal
servers and services.
Troubleshooting of network problems is greatly
simplified. Rather than attempting "trial and error"
to debug network problems, you can be instantly
notified of specific problems. Some kinds of
problems can even be repaired automatically.
Manuscript received.
Umeh O. A., Electronic and Computer Engineering, Nnnamdi Azikiwe
University, Awka, Anambra State, Nigeria.
Akpado K.A., Electronic and Computer Engineering, Nnnamdi Azikiwe
University, Awka, Anambra State, Nigeria.
Okechukwu G. N., Electronic and Computer Engineering, Nnnamdi
Azikiwe University, Awka, Anambra State, Nigeria.
Ejiofor H. C., Electronic and Computer Engineering, Nnnamdi Azikiwe
University, Awka, Anambra State, Nigeria.
Network performance can be highly optimised.
Without effective monitoring, it is impossible to fine
tune your devices and protocols to achieve the best
possible performance.
Capacity planning is much easier. With solid
historical performance records, you do not have to
"guess" how much bandwidth you will need as your
network grows.
Proper network usage can be enforced. When
bandwidth is a scarce resource, the only way to be
fair to all users is to ensure that the network is being
used for its intended purpose.
Fortunately, network monitoring does not need to be an
expensive undertaking. There are many freely available open
source tools that will show you exactly what is happening on
your network in considerable detail. This paper will help you
identify some invaluable tools and how best to use them
(http://wndw.net).
A number of researches have been done to study the
performance on IEEE 802.11 especially on DCF mechanism
both in real-time and using computer modeling and simulation
technique. The throughput, frame discard probability, and
average frame delay performance of DCF in IEEE 802.11 are
analyzed and evaluated for different parameters in (Chen and
Liu, 2010). In (Amjad & Shami, 2006), the authors propose a
new MAC protocol that modifies the DCF protocol such that
the channel utilization can be improved with successful
packet transmissions, yielding higher throughput
performance. Certain research papers aim to propose new
analytical models for investigating the impact of some factors
on the performance of IEEE 802.11. In Zheng et al., (2006),
the authors provide a new analytical model that considers the
channel error conditions in the unsaturated mode to analysis
delay and throughput performance of IEEE 802.11 DCF
under different incoming traffic conditions. Ivanov et al.,
(2010) consider the 802.11 networks which are defined in
terms of throughput requirements and packet loss probability
limitations and the influence of sizes of packets being
transmitted through the network on the QoS is investigated.
Yang et al., (2009) analyze the goodput of a WLAN with
hidden nodes under a non-saturated condition.
This paper makes an in-depth investigation into the
performance of Quality of Service parameter (Throughput
and Delay) as the number of host varies. Three different tools
were used to carry out real time network performance
measurement, the tools include; NetSress, Jperf and
WireShark
2.0 Real Time Network Performance Measurement
Throughput and Delay Analysis in a Real Time
Network
Umeh O. A., Akpado K.A., Okechukwu G. N., Ejiofor H. C.
Throughput and Delay Analysis in a Real Time Network
28 www.ijeas.org
Three different networks sniffer software were used to carry
out the measurement. The measurement of throughput and
delay were taken at intervals as the number of users‘ increases
or decreases.
2.1 Experimental Environment
This experiment was carried out at Chams Plc office (Old
Secretariat Building by Arroma Junction) Awka, it‘s an
indoor environment. Three different cases were considered in
the experiment. Their network is divided into three regions
namely; Data Capture Center (Ground Floor), Data Update
Center, and Data upload/card center which also houses the
main Server. These three regions have different ranges from
the access points. Each of these centers houses between 15 to
40 fixed desktop computers and few laptops. Some mobile
smart phones were also used as host. All the systems have
wireless LAN features and are IEEE 802.11 compliant. The
network was transmitted to the three regions, each via
Nanostation M5 radio, which brings the network to the
wireless Cisco Router (Cisco 871 model) and distributed via a
wireless AP, LAN and WLAN switches (LinkSys), Hubs and
so on. These three Centers are located in the same building
but are separated with few meters way from each other.
The measurements are carried out in these three locations. In
all the three regions, three different network sniffers
(NetStress, Wireshark and Jperf) were used to monitor and
take measurement on the network.
Netsreess: NetStress is a tool used to measure network
performance, both wired and wireless. It is a simple tool that
employs bulk data transfer using layer 3 protocols (TCP and
UDP). Network performance is reported in terms of
throughput; that is, bits (or bytes) per second.
In order to test and troubleshoot networks, there is need for
tools that can generate network traffic and analyze the
network's throughput performance. This is true for both wired
and wireless networks. By quantifying the network's
throughput performance, NetStress provides a valuable
metric to assist in monitoring the health of the network or
assist in troubleshooting network problems.
By comparing actual throughput with the theoretical
bandwidth between the transmitter and receiver or with a
measurement taken at an earlier date, it can tell whether the
network is operating as expected. Variations in throughput
may indicate a significant amount of other traffic, overloaded
network equipment, communication errors which cause
packets to be lost or, in the case of wireless networks,
interference from other wireless devices. By performing tests
using different machines on the network, a network engineer
will begin to gain clues as to where the problem lies and which
areas should be examined in greater detail
(http://nutsaboutnets.com/netstress/).
NetStress includes the following features:
single instance of the application (i.e. each instance
can be used as server or server plus client)
supports both TCP and UDP data transfers
supports multiple data streams
variable TCP / UDP segment size
rate of packet transmission (Packets Per Second)
variable Maximum Transmission Unit (MTU)
uplink and downlink modes
auto node discovery
choice of display units (KBps, Kbps, MBps, Mbps)
support for multiple network adapters
2.2 Features of Netstress
Single Instance of the Application (i.e. each instance can
be used as receiver or receiver plus transmitter): The new
version of NetStress follows a transmitter / receiver model,
but there is no need to be concerned with this when
application is launched for the first time. Now, every instance
of the application includes a built-in receiver; that receiver
may lie dormant or respond to transmissions from a
transmitter. Also, every instance of the application can act as a
transmitter. So, this provides a lot more flexibility since each
instance can act as a receiver and, optionally, as a transmitter.
When NetStress is launched, it will be observed that the charts
have been separated as Transmitter and Receiver. When the
built-in receiver receives transmissions from a transmitter
then the results are displayed in the receiver‘s charts, and
when NetStress is transmitting then the results are displayed
in the transmitter's charts.
TCP and/or UDP -- plus multiple data streams: Supports
TCP transmissions, UDP transmissions or both
(concurrently). Furthermore, you can specify from 0 to 8 data
streams for each protocol. These are configured using the
Settings dialog. In addition, the timecourse results are broken
down accordingly:
Total: The chart labelled Timecourse (Total) shows (a) the
total throughput (both TCP plus UDP), (b) TCP alone (total
of all the TCP data streams), and (c) UDP alone (total of all
the UDP data streams).
TCP: The chart labelled Timecourse (TCP) shows the
throughput results for each of the TCP data streams.
UDP: The chart labelled Timecourse (UDP) shows the
throughput results for each of the UDP data streams.
The default setting is to test throughput performance using a
single TCP data stream; this is the most common scenario.
Packet Size: Supports TCP and UDP packet size. Using the
Settings dialog you can configure the packet size of the TCP
and UDP data streams. Turns out this can have a slight effect
on throughput.
Rate of Packet Transmission: Supports Packets Per Second
(PPS) "throttle" for the transmission side. Using the Settings
dialog you can configure 'packets per second' for both TCP
and UDP data streams. This is useful in emulating voice and
other timed applications.
International Journal of Engineering and Applied Sciences (IJEAS)
ISSN: 2394-3661, Volume-2, Issue-12, December 2015
29 www.ijeas.org
Maximum Transmission Unit (MTU): Using the Settings
dialog you can configure the MTU for the current interface
adapter. Typically, the operating system will optimize this
value when it first boots. This is not a parameter that
Microsoft readily exposes since a bad value can dramatically
degrade network performance -- so, experiment with it at your
own risk. Though NetStress allows you to change this
parameter while the application is running, it will restore the
MTU to its original value when the application exits.
Microsoft Windows computers default to an MTU of 1500
bytes for broadband connections and 576 bytes for dialup
connections.
Display Units: Using the Settings dialog you can configure
which units NetStress should use when displaying the data:
e.g. KBps (KBytes per sec), Kbps (Kbits per sec), MBps
(MBytes per sec) or Mbps (Mbits per sec).
2.3 Using Netstress
In order to measure throughput performance between two
nodes on a network we need a transmitter and receiver.
Packets are transmitted to the receiver, and the receiver, in
turn, sends the result back to the transmitter. The results
represent a quantifiable metric that reflects the performance
of the path between the transmitter and receiver machines. By
selecting the transmitter and receiver machines at various
points within the network one can analyze critical portions of
the data path.
Each instance of NetStress can run as both a transmitter and
receiver, or just as a receiver. If you wish for a particular
instance of NetStress to run just as a receiver then it is not
necessary to specify a remote receiver IP address. On the
other hand, if you wish for a particular instance of NetStress
to run as both a transmitter and receiver, then use the 'Remote
Receiver IP' button along the main menu to select or enter the
IP address of a remote receiver. NetStress uses a UDP
broadcast mechanism to automatically discover other
instances of NetStress on the network that can act as a remote
receiver. If no remote receivers are listed below this is
probably because NetStress is not running on another
machine. Then the IP address of the remover receiver can be
entered manually. There is one requirement, that is the
remote receiver must be reachable from the transmitter using
ICMP (i.e. ping).
2.4 Procedure for Running NetStress
1) Launch NetStress on station A; call this "Node A". A
dialog appears with a list of available network interfaces,
choose one.
2) Launch NetStress on station B; call this "Node B". A dialog
appears with a list of available network interfaces, choose
one. Be aware that in order for the two instances of NetStress
to be able to communicate then the interfaces you've selected
must be on the same network. If there is only one network and
each machine has only one NIC, then that is not a problem.
But in the case of multiple networks and/or NICs then it is
necessary to pay attention to this detail.
3) Let's say "Node A" will be a transmitter, then it is necessary
to select a remote receiver node. Along the menu bar you'll
see the label "Remote Receiver IP" and an IP address of
0.0.0.0. The star that moves from side-to-side is a visual cue
that a remote receiver needs to be selected if this instance of
NetStress is to act as a transmitter. Select the blinking '0.0.0.0'
and the 'Select Remote Receiver dialog box will appear.
Select the IP address of one of the remote receivers and press
'OK'.
4) Once a remote receiver has been selected, then the
'Settings' and 'Start' buttons along the top menu are activated.
The 'Settings' dialog box allows you to control the following
parameters: TCP vs UDP, Number of data streams, TCP
Packet Size, UDP Packet Size, Rate of Packet Transmission
(Packets Per Second), Data Flow, MTU, Display Units etc.
5) While transmitting, certain buttons on the main menu
change state, for example the Stop button now becomes
active. The Settings, ‗Start‘, and 'Remote Receiver IP' buttons
are temporarily deactivated.
6) To stop transmitting, press the Stop button.
7) Below the main menu there are two main windows , that is
'Transmitter' and 'Receiver'. When NetStress is acting as a
transmitter then the timecourse charts in the upper window
will display the results. When NetStress is acting as a remote
receiver then the lower window will display the results
(https://nutsaboutnets-documentation.s3.amazonaws.com/Ne
tStress).
Figure 1: Pictorial Diagram of Throughput Measurement
Wireshark: Wireshark is the world's foremost open-source
packet/network protocol analyzer. It is used for network
troubleshooting, analysis, software and communications
protocol development, and education. It lets you see what's
happening on your network at a microscopic level. Originally
named Ethereal, the project was renamed Wireshark in May
2006 due to trademark issues.
Wireshark is cross-platform, using the GTK+ widget toolkit
in current releases, and Qt in the development version, to
implement its user interface, and using pcap to capture
Throughput and Delay Analysis in a Real Time Network
30 www.ijeas.org
packets; it runs on Linux, OS X, BSD, Solaris, some other
Unix-like operating systems, and Microsoft Windows.
Wireshark, and the other programs distributed with it such as
TShark, are free software, released under the terms of the
GNU General Public License (https://www.wireshark.org).
Features: Wireshark is software that "understands" the
structure (encapsulation) of different networking protocols. It
can parse and display the fields, along with their meanings as
specified by different networking protocols. Wireshark uses
pcap to capture packets, so it can only capture packets on the
types of networks that pcap supports.
Data can be captured "from the wire or wirelessly" from a live
network connection or read from a file of already-captured
packets. Live data can be read from a number of types of
network, including Ethernet, IEEE 802.11 or PPP. Captured
network data can be browsed via a GUI, or via the terminal
(command line) version of the utility, TShark.
Wireshark has other rich feature which includes the
following:
Deep inspection of hundreds of protocols, with more
being added all the time
Live capture and offline analysis
Standard three-pane packet browser
Multi-platform: Runs on Windows, Linux, OS X,
Solaris, FreeBSD, NetBSD, and many others
Captured network data can be browsed via a GUI, or
via the TTY-mode TShark utility
The most powerful display filters in the industry
Rich VoIP analysis
Captured files can be programmatically edited or converted
via command-line switches to the "editcap" program. Data
display can be refined using a display filter.
VoIP calls in the captured traffic can be detected. If encoded
in a compatible encoding, the media flow can even be played.
Raw USB traffic can also be captured. Wireless connections
can also be filtered as long as they transverse the monitored
Ethernet.
Various settings, timers, and filters can be set that ensure only
triggered traffic will appear.
Wireshark's native network trace file format is the libpcap
format supported by libpcap and WinPcap, so it can exchange
captured network traces with other applications that use the
same format, including tcpdump. It can also read captures
from other network analyzers, such as snoop, Network
General's Sniffer, and Microsoft Network Monitor
(https://en.wikipedia.org/wiki/Wireshark).
2.5 Colour Coding
Wireshark uses colours to help you identify the types of traffic
at a glance. By default, green is TCP traffic, dark blue is DNS
traffic, light blue is UDP traffic, and black identifies TCP
packets with problems — for example, they could have been
delivered out-of-order.
Figure 2: Pictorial diagram of Network parameter
measurement
Jperf: Jperf is a tool to measure the bandwidth and the quality
of a network link. Jperf can be associated with Iperf to
provide a graphical frontend written in Java. The network link
is delimited by two hosts running Iperf.
The quality of a link can be tested as follows:
The bandwidth is measured through TCP tests.
Latency (response time or RTT): can be measured
with the Ping command.
Jitter (latency variation): can be measured with an
Iperf UDP test.
Datagram loss: can be measured with an Iperf UDP
test.
2.6 How to Measure Network Throughput Using Jperf
JPerf is a graphical front end for the popular network testing
tool Iperf. Using JPerf you can quickly test a WAN or LAN
connection to determine the network throughput and delay.
The test results are automatically graphed and presented in a
format that is easy to read. JPerf can also be used to detect
packet loss, delay, jitter, and other common network
problems.
In WLAN, JPerf testing can also be used to perform; site
surveys, validate client performance, verify throughput across
802.11 bridges and access points.
JPerf provides many benefits over Iperf which is a command
line only application. Jperf is reliable and easy to use. The
utility is fully operational on both Windows and Linux
systems.
International Journal of Engineering and Applied Sciences (IJEAS)
ISSN: 2394-3661, Volume-2, Issue-12, December 2015
31 www.ijeas.org
Whether you're trying to diagnose a problem in your home
network or troubleshoot the performance of a WLAN link,
JPerf can handle the task (https://code.google.com/p/xjperf/).
2.7 Installing JPerf on Windows
JPerf requires that Java version 1.5 or newer is installed
before it will run. You can visit Java.com to download the
latest version or verify if it is correctly installed on your
computer.
To get JPerf running you will need to download the
jperf-2.0.2.zip file from the JPerf Google code page. There
isn't an installer so simply extract the contents of the zip file to
a location on your computer such as C:\JPerf. To launch the
JPerf utility run ‗jperf.bat‘.
2.8 Setting up a JPerf Server
JPerf is designed to run as a client/server application. To run a
test you will need to set up a JPerf server on your network.
Then you can run a JPerf client from another location on the
network which will connect to the remote server.
To start the JPerf server select the radio button labelled server
then click Run IPerf. By default JPerf runs in TCP mode and
listens on port 5001
(www.techrepublic.com/using-jperf-to-check-network-perfor
mance/).
2.9 Connecting a client to the server
To connect to the JPerf server to run a test there is need to first
select the client radio button. In the server address field type
in the IP address of the computer running the JPerf server. To
begin the test click on run iPerf in the upper right hand corner
of the app.
By default JPerf will run a 10 second TCP test using 1 stream.
While the test is running the graph will update in real time to
reflect the results.
There are several options that can be adjusted to modify the
parameters of the test, these may include;
no arg. Default settings
-b Data format
-r Bi-directional bandwidth
-d Simultaneous bi-directional bandwidth
-w TCP Window size
-p, -t, -i Port, timing and interval
-u, -b UDP tests, bandwidth settings
-m Maximum Segment Size display
-M Maximum Segment Size settings
-P Parallel tests
-h help
More so, there are several TCP options that can be modified
such as buffer length, window size, and Round trip Time.
JPerf can also function in UDP mode, although the server
must be operating in UDP mode in order for this test to work.
2.10 Application layer options in Jperf
Transmit - Run the test for a specified number of seconds, or
until a certain amount of bytes have been transferred.
Output Format - Test results can be changed to display bits,
bytes, kbytes, etc.
Report Interval - This adjusts how often the graph results are
updated.
JPerf Tips: Below are a few useful tips for improving your
JPerf results;
Use Parallel streams - The bandwidth of a single TCP
session is limited by several factors. By using parallel streams
you can easily saturate a very high bandwidth connection. In
the JPerf client settings you can specify the number of streams
to use. 10 is found to be a good number.
Run a Bi-Directional Test - By default JPerf transmits data
from the client to the server. By selecting the dual testing
mode under application layer options JPerf will send data in
both directions at the same time.
Use a representative file - JPerf has a cool ability that allows
you to select a file to be transmitted to the server during the
test. This function allows you to simulate a real world data
transfer across your network in a controlled manner.
Use JPerf to create iPerf commands - Since JPerf uses iPerf
as a back end to run all of the tests you can use JPerf to help
you build useful iPerf commands. Select the test options you
want using the GUI and then copy the command it created
from the box at the top of the application (www.firewall.cx).
Figure 3: Pictorial Diagram of Bandwidth Measurement
Throughput and Delay Analysis in a Real Time Network
32 www.ijeas.org
Figure 4: Pictorial Diagram of Bandwidth and Jitter
Measurement
3.0 Test bed Environment
Test bed one: Data upload/card Center: The first
experiment was carried out in Data upload/card Center which
houses the main servers. The Data upload/card Center is
located on the first floor of the old secretariat two storey
building and was used for the measurements; first was with
five hosts, second was with ten host, third was with 15 and it
continues in that order till we have fifty work stations. The
measurements of throughput and delay/jitter were carried out
using the three different network sniffers one at a time.
Test bed Two: Data Update Center: The second
experiment was carried out in Data Update center, which is
about 50meters from the data upload center. It‘s also located
at the 2nd floor of the building. The same procedure was also
used here to carry out measurements in this center. In the first
scenario, five hosts were used; as the second ten were used; in
the third fifteen were used and so on up to fifty work stations.
The readings were recorded in table 4.8 (throughput) and 4.9
(mean delay).
Test bed Three: Data Capture center: The third
experiment was carried out in the data capture center which is
located at the ground floor of the building. It‘s about
100meters away from the access point. Signal measurements
were taken and recorded accordingly as shown in table 4.8
and 4.9. Five host were used in the first scenario; ten were
used in the second scenario while fifteen, twenty, and up to
fifty work stations were used respectively.
Measurements were carried out on each of the test beds using
three network sniffers viz; NetStress, Whireshark and Jperf.
The settings of the access point (Wireless Router) have been
pre-configured and the network sniffer was used to measure
the network throughput and delay.
Network packet delay was considered as being comprised of
packet access delay, propagation delay and processing delays.
The average delay was processed as expressed in equation (1)
below (Klenrock and Tobagi, 2010).
Where,
M = Total number of packets transmitted.
THROUGHPUT FOR THE
THREE TEST
No of work stations
THR1
THR2
THR3
2
5.295
5.003
4.963
5
4.283
4.532
4.185
10
3.743
4.009
3.861
15
3.364
3.736
3.375
20
2.571
3.072
2.843
25
2.295
2.654
2.579
30
1.782
1.849
1.943
35
1.023
1.329
1.465
40
0.743
0.843
1.275
45
0.532
0.437
0.732
50
0.529
0.419
0.529
Data
Uplo
ad/ca
rd
cente
r
Data
Capt
ure
cente
r
Nan
osta
tion
M5
5.8
GH
z
Data
Upda
te
cente
r
Na
nos
tati
on
N2
2.4
GH
z
P
o
l
e
C
at
6
ca
bl
e
Figure 5:
Experimental
Network
Architecture.
International Journal of Engineering and Applied Sciences (IJEAS)
ISSN: 2394-3661, Volume-2, Issue-12, December 2015
33 www.ijeas.org
Also recall that;
Note also that;
Equations (1, 2, 3 and 4) were used to compute the
Transmission Delay for a particular packet. If the Date size
and Bite rate are known, the Transmission Delay can be
calculated.
Throughput is defined as the number of bits passing through a
point in a second or it is defined as the number of packet
passing through the network in a unit time (Klenrock and
Tobagi, 2010), it can also be stated as;
)
Also,
Therefore,
Equations 4 to 8 are used to manually compute the
Throughput value of a particular traffic or packet, be it TCP
or UDP traffic pattern; this was done to verify the measured
data. The maximum throughput which is sometimes regarded
as the bandwidth is always less than the network performance
throughput.
The reading for Throughput was recorded, transferred to
Microsoft Excel spreadsheet program for more clarity as
shown in table 1 below.
Table 1: Table of values for throughput against number of
workstations in the three regions
From the above reading, the graph of Throughput was plotted
against the number of work stations using Microsoft Excel;
the graph is as shown in figure 6 below. The graph shows the
effect of number of work station against network throughput.
Figure 6: Graph of Throughput against Number of Work
Stations in the three Regions
Delay reading was also collated and recorded, transferred to
Microsoft Excel spreadsheet program for more clarity as
shown in table 2 below.
Table 2: Table of Values for Mean Delay against Number of
Workstations in the three Regions
From the above reading, the graph of Delay was plotted
against the number of work stations using Microsoft Excel,
the graph is as shown in figure 6 below. The graph shows the
effect of number of work station against network Delay.
Delay for the three regions
Number of Work Stations
D1
D2
D3
5
0.257
0.401
0.448
10
0.474
0.504
0.621
15
0.671
0.811
0.883
20
0.894
1.16
1.207
25
1.083
1.24
1.282
30
1.16
1.237
1.294
35
1.236
1.247
1.253
40
1.252
1.269
1.301
45
1.312
1.326
1.337
50
1.354
1.377
1.398
Throughput and Delay Analysis in a Real Time Network
34 www.ijeas.org
Figure 6: Graph of Mean Delay against Number of work
stations in the three regions
4.0 Measurement Analysis
When we ran the software(s) on the network, the results
reported a throughput of approximately 694,030 to 54,920
bytes- per-second. So, how does this compare with the
theoretical maximum of 11 Mbps? 11 Mbps is equivalent to
1,441,792 bytes-per-second (11 x 1024 x 1024 bits / 8 bits /
byte). So, is our actual throughput (which is roughly 48% to
3.8% of the theoretical) reasonable? The short answer -- yes.
The 11 Mbps is the theoretical maximum of what the
hardware and medium are capable of. There are numerous
factors that can contribute to the difference -- including
network traffic, interference from other wireless devices and,
equally important, the overhead of the 802.11 and TCP
protocols. The throughput we measure doesn't take into
account that every 802.11 packet includes additional bytes
besides the data payload.
Figure 6 however, shows that increase in the number of work
station(s) will increase the mean delay of a wireless network.
5.0 Conclusion
The objective of this research is to carry out a real time
performance monitoring of IEEE 802.11 compliant network,
by investigating the effect of varying the number of work
stations on the Quality of Service parameter on WLAN.
We have concluded that the throughput and delay
performance strongly depends on the number of stations of
the wireless network. Moreover, if the network is composed
of a small number of stations and for small length frames, the
network will have better performance.
In this thesis, however, if the number of workstations
increases to the point of network saturation, both mean packet
delay and throughput performance of the IEEE 802.11
protocol degrades significantly. Similarly, it was also shown
that the mean packet delay of arrived packets increases as the
number of workstations increases at saturation.
Therefore, to achieve a better enhanced network performance,
it was observed that the IEEE 802.11b WLAN requires an
improvement on its window back off algorithm and fairness.
More so, future work can include the throughput and delay
analysis including the effect of hidden stations. Another
possible area of research is a consideration of an erroneous
wireless channel.
References
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Performance of IEEE 802.11 Distributed Coordination Function.
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[2] Chen, R., and Liu, X. (2010). Performance Evaluation over IEEE
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[3] https://code.google.com/p/xjperf/
[4] https://en.wikipedia.org/wiki/Wireshark
[5] http://nutsaboutnets.com/netstress/
[6] https://nutsaboutnets-documentation.s3.amazonaws.com/NetStres
s
[7] http://wndw.net/pdf/wndw3-en/ch16-network-monitoring.pdf
[8] https://www.wireshark.org
[9] Ivanov, S., Botvich, D., and Balasubramaniam, S. (2010). Joint
Throughput and Packet Loss Probability Analysis of IEEE
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Communications, pp. 673-676.
[10] Klenrock L. and F. Tobagi, ―Packet Switching in Radio Channel:
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[11] www.firewall.cx/Downloads/Administrator Utilities
[12] Yang, J. W., Kwon J. K,. and Hwang, H. Y. (2009). Goodput
Analysis of a WLAN with Hidden Nodes under a Non-Saturated
Condition. IEEE Transactions on Wireless Communications,
8(5), pp. 2259 -2264.
[13] Zheng, Y., Lu, K., Wu, D., and Fang, Y. (2006). Performance
Analysis of IEEE 802.11 DCF in Imperfect Channels. IEEE
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