EVALUATING THE USAGE OF WIRELESS BROADBAND

HOTSPOTS

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.

1 INTRODUCTION

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 BACKGROUND

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

136

Hunaiti Z., Rahman A., Balachandran W. and Huneiti Z. (2005).

EVALUATING THE USAGE OF WIRELESS BROADBAND HOTSPOTS.

In Proceedings of the Second International Conference on e-Business and Telecommunication Networks, pages 138-141

DOI: 10.5220/0001407701380141

 SciTePress

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).

3 TESTBED

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.

4 EXPERIMENTS AND RESULTS

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

www.brunel.ac.uk

Brunel University

Network

Firewall

100 Mbps

VPN Gateway

VPN Tunnle

WLAN

Access Point

EVALUATING THE USAGE OF WIRELESS BROADBAND HOTSPOTS

137

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

bytes/s.

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.

5 DISCUSSION OF RESULTS

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

applications.

Hotspot Upload

5000

10000

15000

20000

25000

30000

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

seconds

Bytes

Figure 2:. Upload throughput

Hotspot Download

10000

20000

30000

40000

50000

60000

70000

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]

Bytes

Figure 3:. Download throughput

Hotspot latancey

100

150

200

250

300

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

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138

6 CONCLUSIONS

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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Available:

ttp://www.btopenzone.com/find/hotspots_explained.js

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