Ziad Hunaiti, Ammar Rahman, Wamadeva Balachandran
School of Engineering and Design,Brunel University,Cleveland Rd.,Uxbridge,UB8 3PH UK
Zayed Huneiti
Hail Community College,King Fahad University of Petrolume and Minirals, Saudi Arabia
Keywords: WiFi, Hotspots, VPN.
Abstract: This paper will discuss the results obtained from testing and evaluating the performance of public Wireless
local Area Network (WLAN) hotspots in real life. A fully detailed analysis of a specially constructed test-
bed will be given. The construction was based on standard user equipments and provided near reality
performance results. The paper will also present an overview of the bandwidth and quality of
communication received by end-users. BT Openzone was chosen as the Hotspot provider to implement and
carry out the tests. The results of these tests have shown the suitability of the public wireless networks in the
United Kingdom to quality-critical applications.
In recent years, many countries around the globe
have started to deploy wireless broadband
technologies. This allowed Internet users to have
high speed Internet access over wireless networks
(i.e. Hotspots). These are available in different
places including public and private networks.
Hotspots are wireless Internet access places which
offer broadband Internet access. Using a wireless-
enabled laptop or a Personal Digital Assistant
(PDA), users can access the Internet and Internet
associated services via hotspots in cafes, motorway
service stations, conference centres, hotels, shopping
centres and airports world wide at considerably
higher speeds than conventional modems. Combined
with other technologies such as Virtual Private
Networks (VPN) , the concept of the office has been
redefined for many of the businesses. With most of
the information being digital a business deal can be
made on coffee shop table or alternatively, the
company’s financial reports can be revised while
waiting for a flight in the airport. The amount of
possible application is massive if these Hotspots can
deliver what they promise (Iyer et al. 2003)
2.1 Public WLAN Hotspot
As the demand for digital data increases the demand
for methods to access this data anytime and
anywhere increases. With the advancement of
mobile technology, the perception of mobility has
changed from user mobility across computers to the
computer being mobile with the user. Subsequently,
data access technologies have moved from wired to
publicly available wireless networks. Several
companies have started to deploy Public Wireless
Local Area Network (WLAN) known as Hotspots
around the globe. BT is one of the companies that
started the implementation of Hotspots in the UK.
Currently available BT public hotspots are designed
to provide access to the internet at speeds of up to
500 kbps which is almost 10 times faster than a
standard 56K modem. With such speeds, users can
send and receive large quantities of information at
broadband speed. A single access point can cover an
area up to 100 meters away from it. BT hotspots are
currently based on the IEEE 802.11b Wireless LAN
protocol which used the 2.4GHz radio frequency.
These can be used to wirelessly access public
internet services in addition to private corporate
Hunaiti Z., Rahman A., Balachandran W. and Huneiti Z. (2005).
In Proceedings of the Second International Conference on e-Business and Telecommunication Networks, pages 138-141
DOI: 10.5220/0001407701380141
networks using Virtual Private networks (VPNs)
(Iyer et al. 2003)(BTOpenZone ).
2.2 Virtual Private Networks (VPN)
Since the first deployment of data networks in
corporations, the need for intercommunication
between them has came into attention. Companies
have historically used leased lines and ISDN
internetworking solutions between its offices to
make a Wide Area Networks (WANs). WANs had
obvious advantages over dialup servers such as
reliability, security and performance. Unfortunately,
WANs had two main disadvantages; the first being
is the inflexibility of such a solution. Access to such
network is restricted from sites where the leased line
is connected or where there is ISDN on that site. The
second disadvantage is the overhead costs for
maintaining such networks. This took WAN out of
the solutions list for small and medium enterprises.
During the last few years, companies have
started implementing their own Virtual Private
Networks (VPNs). These are private networks that
use public networks (usually the internet) as an
intermediate communication medium. It creates a
virtual tunnel between different company’s sites.
Every user is authenticated separately in a very
secure manner. VPN security provides four different
layers of security which makes it a very safe option
for corporations. In general VPNs offeres a cheaper
and more flexible alternative to WANs without
jeopardising the security of the firm. It provides a
lower cost of ownership and maintenance, which
leads to a faster return on investment. It also
provides flexibility on different levels. Once a VPN
is established, the number of users can be easily
increased according to the organization needs at a
very low cost. Geographically speaking, a VPN
using the Internet as a medium can theoretically be
accessed from anywhere in the world at a very low
cost. This became very useful for companies with a
high global coverage, where connecting a WAN to
hundreds of small offices and branches was
financially unfeasible. Another major application
came with the spread of mobile computing. Users
can now connect to their corporate networks while
they are travelling using Hotspots or widely
available mobile phone networks (Strayer 2004)
(Andersson 2001).
A testbed has been constructed as shown in figure
using the available infrastructure of Brunel
University network and BTopenzone in order to
collect real results from a live network. A mobile
terminal (laptop) running VPN client software was
connected to a BTOpenZone hotspot access point
via WLAN 802.11b network card. Access to Brunel
University FTP and web servers was established via
a VPN tunnel. The testbed setup has been chosen in
a way to reflect a real-live scenario, covering a wide
range of possible applications.
In order to evaluate the general performance of
the network, test has been performed to assess the
main link characteristics (Hunaiti et al.
2004)(Chakravorty, Pratt 2002)(Chakravorty, Clark
& Pratt 2005), which include: upload throughput,
downlink throughput, Round-Trip Time (RTT) and
packet loss. These parameters can reflect the
performance of the majority of applications. For
measuring uplink and downlink throughput,
Microsoft network performance analyzer was used.
This allowed the capture of both uplink and
downlink traffic between the mobile terminal and
the FTP server. For measuring Round-Trip Time
(RTT) and packet loss, ping command from DOS
command prompt has been used. Pinging Brunel
University web server “www.brunel.ac.uk"
presented the round trip delay and the percentage of
lost packets between the mobile terminal and the
web server.
Throughput test: The throughput test was
performed to investigate the real data transfer speed
that can be achieved over a real life hotspot. Both
uplink and downlink throughputs were tested.
Throughput measurements were based on measuring
the transfer speed between the mobile terminal (the
Figure 1: Testbed
WLAN 802.11b
VPN Client
BT OpenZone
Public Internet
FTP Server
Web Server
Brunel University
100 Mbps
VPN Gateway
VPN Tunnle
Access Point
laptop) and the FTP server. For uplink throughput
test files were sent from the mobile terminal to the
FTP Server. The sent data was captured by
Microsoft network performance analyzer. As Figure
2 shows that uplink transfer speed ranged between
7669 to 28409 bytes/s with average speed of 19891
In the second part of the throughput test, the
downlink throughput was measured by downloading
files from the FTP sever to the mobile terminal unit.
The received data was captured by Microsoft
network performance analyzer, downlink speed test
results are shown in figure 3. The minimum
recorded downlink speed was around 39868 bytes/s,
the maximum speed achieved was 59632 bytes/s
with an average of 56736 bytes/s.
Latency: For testing the latency Round-Trip
Time (RTT) test was performed. RTT indicates the
time that a message takes to get to the destination
receiver and back again to the sender. RTT test was
undertaken to measure the latency between the
mobile terminal and Brunel University web server
(www.brunel.ac.uk). RTT test was undertaken using
the ping command from DOS command prompt
under Windows XP operating system. Ping
command basically sends an Internet Control
Message Protocol (ICMP) to the destination server
and awaits the results. This particular type of
messages does not require any processing at the
destination server, and the time that it takes to go
back and forth should reflect the total time that it
takes to travel that distance twice. The result in
Figure 4 shows that latency was between 37 and
270ms with an average round-trip latency of 108ms.
Packet loss: The packet loss test was conducted
in order to find the amount of lost packets within the
link between the mobile terminal and the web server.
The test was performed in the same way as in the
latency test. Once again ping commands was
employed. In each ping command 100 packets were
sent to the web server. The report includes the
percentage of lost data. Our test resulted in no lost
packets at all. This shows that the Hotspot provided
an optimum communication medium. This result
could be a result of the Hotspot being in an optimal
scenario i.e. The distance to the access point was
relatively close in addition to the low load on that
particular Hotspot.
The evaluated parameters of network performance
were chosen on the basis of their importance of them
to the majority of applications. Bandwidth tests,
showed high enough average throughput for the
majority of applications on both uplink and
downlink channels. The results also show that
fluctuation around the average is not very high. This
indicates the reliability and the stability of these
channels. The results from the latency test have
shown that the incurred delays were reasonable. The
average RTT was 108 ms, which could be
considered a low delay for a wireless channel. This
also shows the suitability of hotspots for real-time
Hotspot Upload
1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106 113 120 127 134 141 148 155 162 169 176 183 190 197 204 211 218 225 232
Figure 2:. Upload throughput
Hotspot Download
1 13 25 37 49 61 73 85 97 109 121 133 145 157 169 181 193 205 217 229 241 253 265 277 289 301 313 325 337 349 361 373 385
Time [Sec]
Figure 3:. Download throughput
Hotspot latancey
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300
ICMP seq.no
RTT [ms]
Figure 4. Round-trip latency
At this paper performance evaluation has been
conducted on the commercially available BT WLAN
hotspot. The outcome from tests has shown a highly
appraisable performance of this technology. That
makes it a very suitable solution for corporate
applications. As it is demonstrated in the testbed,
WLAN Hotspots can make a valuable extension for
the corporate networks by using VPN technology
access to the enterprise local network. This provides
the employees with the extra freedom they need to
accomplish their jobs wherever they are.
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