The Analysis and Design Strategy in the Deployment of
Wireless Communications for Innovative Campus
Networks
Jamaludin Sallim
Faculty of Computer Systems & Software Engineering,
University College of Engineering & Technology Malaysia
Locked Bag 12, 25000 Kuantan, Pahang, Malaysia.
Abstract. This
paper describes the fundamental concept of analysis and design
strategy for an effective deployment of wireless communications for innovative
universities or colleges campus that insistently deploys the wireless networks.
The extensive use of wireless technologies in university campus has made
various respective computer applications such as electronic transactions and
electronic learning (e-learning) environments become more energetic. Usually,
for the innovative campus network, when deploying wireless communications,
most IT Managers/Engineers begin the project by jumping into technical
matters, such as deciding upon which approach, technique or standard to use,
which vendor to select, and how to overcome the various limitations. These are
important elements of implementing wireless communications for innovative
campus; however prior to getting too far with the project, the respective IT
Managers/Engineers must give vigilant attention to analysis and design strategy
in order to wind up with an effective deployment.
1 Introduction
Innovative campus doesn’t mean ‘new campus’ but it refers to learning and teaching
environment that desires sophisticated infrastructure and electronic-based transactions
with latest and appropriate technology. Supported by advanced technologies, an
innovative campus is designed to optimize efficiencies of management, education,
and research productivity of the campus, through systematic management of campus
information flows.
The innovative universities, with many students, should deploy sufficient wireless
com
munications throughout the campus. Students and faculty are able to take
advantage wireless solution. Since the usage at the various faculties growing rapidly,
officials needed to ensure students and faculty had enough bandwidth to do research
and studies now and into the future. The wireless network covers much, but not all of
the campus, including many open spaces, because of leakage from surrounding
buildings. It is possible to walk across campus without losing connection. If the
connection is lost, eg, when changing floors within a building, then it is automatically
restored without needing to log on again.
Sallim J. (2005).
The Analysis and Design Strategy in the Deployment of Wireless Communications for Innovative Campus Networks.
In Proceedings of the 4th International Workshop on Wireless Information Systems, pages 124-137
DOI: 10.5220/0002572101240137
Copyright
c
 SciTePress

Higher bandwidth applications are needed to support the broad variety of
academic programs at the university. In campus, wireless communications also
encourages students to use laptops so the freedom to move around in a lab or other
locations and still have access to the intranet or internet from anywhere is critical.
Requirements analysis of wireless deployment in campus includes immediate and
future needs of the users, university, and the existing information system.
Requirements analysis are what the wireless communications must comply with, such
as range, throughput, security, battery longevity, application software, operating
systems, end-user hardware, etc. Some of these requirements are obviously different
and more complex than what we need to consider for wired networks, so we should
pay closer attention when deploying wireless solutions.
Keep in mind that the intent of defining the requirements is to determine what the
wireless communications must do, not how it will do it. Avoid making technical
decisions when defining requirements unless there is company mandates in place that
tell us otherwise. For example, the selection of 802.11b over 802.11a is likely not a
requirement. Our choice of 802.11b in the requirements stage could limit the ability to
support other requirements not yet known. Before making that selection, we first need
to fully understand other requirements, such as throughput requirements of
applications, number of end-users, ranges, etc. It's best to leave the technical decisions
to the design stage after all requirements are well defined and agreed upon.
After we have a firm set of requirements then we will focus on design. This
determines how we are going to satisfy requirements with least cost. Consider
technical alternatives for satisfying the requirements by choosing appropriate
standard, selecting a vendor, identifying access point locations, assigning channels to
access points, choosing security mechanisms, etc. The design should fully describe
what components and configurations are necessary to satisfy the requirements.
Through the design process, produce a design specification that highlights the
chosen design elements and provides a diagram indicating the placement of access
points within the facility. For smaller networks, we may only spend a day or so
designing the solution. In larger implementations, it may take weeks or months to
fully define enough technical detail before moving forward with the acquisition of
hardware and installation services. These larger projects will likely benefit from
simulation, prototyping, or pilot testing as part of the design to ensure we have made
the right choices and the requirements are fully realizable.
2 Campus Wireless Deployment Considerations
Ahead of deploying a wireless installation in campus, a typical study should be made
by obtaining the feedback from other campuses or educational institutions that already
deployed wireless communications at their premises. This is very important in order
to identify the deployment considerations such as RF interference, poor performance,
and security holes will wreak havoc. By handling considerations during the early
phases of the deployment, we will significantly increase the success of an innovative
campus wireless communications. With a firm understanding of requirements, we
should consider the following elements when evaluating and resolving considerations
for deploying wireless communications:
125

2.1 RF interference
RF interference is still plaguing wireless communications deployments. Many
universities have gotten by without any problems, but some have installations that
don't operate as well as planned. The perils of interfering signals from external RF
sources are often the culprit. As a result, it's important that we're fully aware of RF
interference impact and avoidance techniques.
2.2 Interoperability issues
For huge campus that have various building infrastructure, multi-type of user, access,
applications and already deployed various wireless product will contribute to this
considerations. The lacks of interoperability among various wireless standard such as
802.11 FHSS, 802.11b DSSS, and 802.11a OFDM causes problems in some cases.
Even though these standards are all 802.11, they don't interoperate with each other.
With so many standards, we run the risk of not allowing some users on the wireless
communications.
2.3 Security issues
Security is essentially one of the crucial issues related to the project. The avenues of
attack and considerations which involves physical security, network security and
application security are the main issues in wireless communications. Many
universities use wireless Ethernet as a drop-in replacement for Ethernet when mobility
is needed or when wiring is difficult or impossible. Some historic or old building are
very limited in wiring possibilities so wireless Ethernet in the only option for network
communications. Network that permit roaming are often large and cover vast
distances. Furthermore the potential for an unauthorized person accessing corporate
information is a significant threat for wireless communications.
2.4 Applications interfaces
In some cases, interfaces with applications located on various hosts and servers can
bring about major problems when using a wireless communications. A relatively short
loss of communications due to RF interference or poor coverage area causes some
applications to produce errors. This occurs mostly with legacy applications lacking
error recovery mechanisms for wireless systems.
2.5 Unclear requirements
The deployment of campus wireless communications without first clarifying
requirements, then the wireless connection may not satisfy the needs of the users. In
fact poor requirements are often the reason why information system projects are
unsuccessful. For instant, The Engineering School was one of the first buildings to be
126

wired, and now requires its students to have laptops. Many of the 800 students are
now moving to wireless, but the building was designed for 2 Mb/s. They have 16
access points in the building; but are looking to redesign the network. Thus, this type
of requirements must be identified clearly.
2.6 Product availability
Solid requirements and an effective design significantly reduce most deployment
considerations, assuming the design specifies products that are actually available
when we need them. The trouble is that vendors often miss projected release dates and
have limited volumes when the products are first available.
3 Deployment Analysis
For the innovative campus network, there is some common wireless communications
requirements analysis in the order in which we should define them:
3.1 Facility
A facility describes what the universities provide that includes the floor plan, type
construction, and possible locations for mounting access points. All of this will
capture the environment in a way that will help us choose the right design
alternatives. Wireless communication is perceived as more flexible and convenient for
campus based students and good preparation for the realities of mobile computing in
real working life. Also, staff perception of wireless communication is that it is just an
access technology and that the major pedagogical change was the move to laptops.
There seems little overt thinking about new pedagogical opportunities created by
mobile computing, although some developments in Equine Studies, using PDAs to
collect data and feed it into the network are evidence of creativity.
3.2 Applications
Ultimately, the wireless communications must support electronic based transaction,
teaching and learning applications, so be sure to fully define them in the requirements.
This could be general office application, such as web browsing, email, and file
transfer. Application requirements enable we to specify throughput and data rates
when designing the system.
3.3 Users
There are various type and number of users (students, lecturers and staff) who will use
the wireless services. It is required to identify whether users are mobile or stationary,
127

which provides a basis for including roaming in the design. Mobile users will move
about the facility and possibly roam across IP domains, creating a need to manage IP
addresses dynamically. Some users, however, may be stationary, such as wireless
desktops.
3.4 Coverage Areas
This is most important requirement that extremely affects the deployment design. The
coverage area can be split to two elements as described as follows:
Coverage from a Single AP
The data rate is a function of distance, so the farther a user is from the AP, the weaker
the signal and the lower the data rate. The distance at which a particular throughput
can be achieved will vary with IEEE 802.11a or 802.11b WLANs. 802.11b has a data
rate of 11 Mbps and a radius of 30 meters (100 feet) when indoors. 802.11a is so new
that detailed measurements on coverage are scarce, but the radio manufacturers
expect that we should be able to get 36 Mbps at a 23-meter (75-feet) radius.
Data Rate
Many APs have an auto-step feature that will automatically decrease their data rates
as the RF signal degrades. So an 802.11b AP is expected to step down from 11 Mbps
to 5.5 Mbps to 2 Mbps to 1 Mbps. Similarly, an 802.11a AP is expected to step down
from 54 Mbps to 36 Mbps to 24 Mbps to 12 Mbps to 6 Mbps. Figure 1 shows the
relationship between data rate and coverage.
Fig. 1. 802.11 association rates are highest closest to the access point
With IEEE 802.11a WLANs we must be in very close range of an access point to
maintain an association rate of 54 Mbps. It’s most realistic that the average user will
be within 15 meters (50 feet) of an access point, which would allow them to maintain
an association rate of 36 Mbps. On the other hand 802.11b will allow a user to
maintain the maximum 11 Mbps association rate at a range of up to 23 meters (75
feet). [4]
128

User Density and Cell Size
The number of users and their applications are major drivers of bandwidth
requirements. The network architect must account for the number of users within the
AP’s cell diameter. In a large office or where user density is high, we should design
smaller cells to achieve a higher data rate, since walls and other objects will not
naturally define the cells. With smaller cells, we will need to re-use frequencies more
often and thus ensure that the channels do not overlap. Figure 2 shows how different
cell sizes will increase throughput and improve the user experience. [4]
100 users per office
11 Mb/s peak 802.11b
3 APs per office
17 Mbps total throughput
100 users per office
11 Mb/s peak 802.11b
5 APs per office
55 Mbps total throughput
Fig. 2. Smaller cells will achieve a higher throughput
2.5 Security
This is a requirement that describe the sensitivity of the information being stored and
sent over the wireless campus network. We might need to identify a need for
encryption if users will be transmitting sensitive information over the wireless
communications.
2.6 End User Devices
It is required to specify the end user devices (e.g., hardware and operating system) to
ensure the solution accommodates them. For instance, we should specify that users
will have laptops running Windows XP or any operating system that have various of
interfaces. This provides a basis for deciding on the type of 802.11 NIC and drivers to
use, as well as assessing the type of middleware that we can use.
2.7 Battery Longevity
The 802.11 NIC will draw current at a couple hundred milliamps and batteries under
this load will last from a couple hours to a day or so, depending on the size of the
battery. These are constraints for most applications, but it's beneficial to indicate the
129

amount of battery life that users will realistically need. The most relevant metrics in
wireless networks is power. Experimental measurements indicate that communication
cost in wireless ad-hoc networks is at least two orders of magnitude higher than
computation costs in terms of consumed power. Note that the coverage problem is
intrinsically global in the sense that, lack of knowledge of location of any single node
implies that the problem may not be solved correctly. Therefore, any algorithm which
aims to provide correct solution must inherently use all location data. [5]
2.8 System Interfaces
In most cases, users will need to access information located in servers on the wired-
side of the system. It is required to describe applicable end-systems and interfaces so
that we can properly design the wireless system interfaces.
2.9 Funding
The requirements stage of a wireless project is a good time to ask how much money is
available. If funding limits are known, then we will know how much we have to work
with when designing the system. In most cases, however, the university management
will ask how much the system will cost. We will then need to first define the
requirements and design the system before giving a cost estimate.
2.10 Schedules
It is required to nail down a realistic completion date, though, and plan accordingly.
For instance, we may be defining our requirements in January, and a retail store will
likely demand that a wireless price marking application be installed by the end of
March.
2.11 Coverage and physical installation restrictions
Part of the end user requirement is a desired coverage area, and possibly some
physical restrictions to go along with it. Physical restrictions, such as a lack of
available electrical power and network connections, can be mundane. Some
universities may also require that access points and antennas are hidden; this may be
to maintain the physical security of the network infrastructure, or it may be simply to
preserve the aesthetic appeal of the building. Some universities may want to provide
coverage outdoors as well, though this is confined to mild climates. Any equipment
placed outdoors should be sturdy enough to work there, which is largely a matter of
waterproofing and weather resistance.
130

4 Deployment Design
Designing wireless network for innovative campus is a new craft, even for many
experienced network architects. When it comes to designing a wired network, most IT
managers or engineers are familiar with the steps to ensure sufficient capacity for the
users and applications. With IEEE 802.11 wireless LANs, a new factor comes into
play: The tradeoff between radio-frequency (RF) coverage and capacity.
4.1 Designing for Signal Loss Factors
A major difference between designing for wired and wireless communications is the
RF signal loss caused by attenuation from walls, doors, windows and other objects in
the building. The building construction also has an impact: Concrete absorbs more
signal than plaster. For instance, a cloth cubicle partition has less attenuation than a
concrete wall.
If we are building an 802.11b network, avoid placing APs within a few feet of
devices that transmit within the same 2.4 GHz frequency, such as the microwave oven
in the lunchroom, any 2.4 GHz cordless phones and Bluetooth devices. 802.11a has
fewer interference problems.
4.2 Computing the Number of APs
Once we know the expected total bandwidth, we need to define a minimum over-the-
air rate at which the system should function. Some locations may exceed that baseline
rate, but we must design for the minimum data rate. For campus-style deployments, a
good rule of thumb is to set these baseline association rates as 11 Mbps for 802.11b
and 36 Mbps for 802.11a. From there, we can compute the number of APs required
for a given service area using the following equation:
Bandwidth x Number of Users x % Activity Rate per User
% Efficiency x Baseline Association Rate per AP
where Percentage Efficiency represents the overall overhead efficiency factor,
including MAC inefficiency and error correction overhead. For instance, using
802.11b technology, a medium-sized call center wants to provide 500 kbps bi-
directional data for 100 employees where the activity rate per user is high throughout
the day. The company wants the maximum association rate per AP – with 802.11b
technology that translates as 11 Mbps up to 23 meters (75 feet) – and the network is
running at 50% efficiency.
The numbers would run like this (multiplying bandwidth by 2 for bi-directional
data):
(2 x 500 kbps) x 100 x 25%
50% x 11 Mbps
131

(1 Mbps) x 100 x 25%
5.5 Mbps
25 Mbps
5.5 Mbps
4.5 = 5 APs needed
Always round up the total to the next whole number to ensure adequate capacity.
Therefore, in this example, five APs are needed to meet the demands of the call-
center’s wireless network capacity. Once we have computed the number of APs
required based on capacity, we need to calculate how many APs are required for
adequate coverage. For high-speed campus deployments, expect that capacity will
exceed coverage. We can compute the extent of the AP’s coverage at a particular
association rate using the receiver sensitivity of the receiving device in conjunction
with propagation analysis.
4.3 Placement and Final Settings of APs
Once we know the number of APs required, we can place them appropriately in the
coverage area and configure their channel assignments. When allocating channels to
the APs, be sure that adjacent APs use non-overlapping channels. 802.11b provides
three non-overlapping channels, while 802.11a offers eight or more, depending on the
country. For high-speed campus deployments, because the number of APs required
for proper capacity is likely to be greater than the number for coverage alone, we will
want to lower the AP’s transmitted power or set the AP’s transmit power
appropriately. This will enable us to re-use frequencies while reducing co-channel
interference (CCI). Be sure that the chosen brand of APs allows the transmit power to
be easily modified from its default (typically maximum) value.
4.4 The Topology Archetype Design
Figure 3 shows how many wireless communications deployments evolve.
132

Fig. 3. Standard wireless deployment topology
Some deployments may look like multiple instances of Figure 3. The topology shown
in the figure provides seamless mobility between the access points connected to the
access point backbone network. In very large deployments, such as a campus-wide
deployment across a large number of buildings, it may be desirable to limit the
coverage areas in which seamless roaming is provided. One common strategy is to
provide seamless mobility within individual buildings, but not provide roaming
between buildings. Each building would have a wireless LAN that looked something
like Figure 3, and all the access point backbone networks would ultimately connect to
a campus backbone.
4.5 Roaming and Mobility Design
In Figure 3, the network linking all the access points, which we call the access point
backbone, is a single IP subnet. To allow users to roam between access points, the
network should be a single IP subnet, even if it spans multiple locations, because IP
does not generally allow for network-layer mobility. To understand this design
restriction, it is important first to appreciate the difference between true mobility and
mere portability. The "single IP subnet backbone" restriction of the design in Figure 3
is a reflection on the technology deployed within most campuses.
133

4.6 Limits on mobility
The access point backbone network must be a single IP subnet and a single layer-2
connection throughout an area over which continuous coverage is provided. It may
span multiple locations using VLANs. Large campuses may be forced to break up the
access point backbone network into several smaller networks, each of which
resembles Figure 3. 802.11 allows an ESS to extend across subnet boundaries, as in
Figure 4.
Fig. 4. Non-contiguous deployments
When a campus is broken into several disjointed coverage areas as in Figure 6, be
sure to preserve the mobility most important to the users. In most cases, mobility
within a building will be the most important, so each building's wireless network can
be its own IP subnet. In some environments, mobility may be restricted to groups of
several buildings each, so the islands in Figure 6 may consist of multiple buildings.
4.7 Address assignment through DHCP
Multiple independent data sets that must be synchronized are an accident waiting to
happen in any field. With respect to wireless LANs, they present a particular problem
for DHCP service. To make life as easy as possible for users, it would be best if
stations automatically configured themselves with IP network information. DHCP is
the best way to do this. Access points frequently include DHCP servers, but it would
be folly to activate the DHCP server on every access point.
4.8 Mobile IP and Roaming
Instead of being fixed in a set location, however, access points note when the mobile
station is nearby and relay frames from the wired network to it over the airwaves. It
does not matter which access point the mobile station associates with because the
appropriate access point performs the relay function. The station on the wired network
can communicate with the mobile station as if it were directly attached to the wire.
Within the context of Figure 3, there are two places to put a DHCP server. One is on
the access point backbone subnet itself. Use a single DHCP server per access point
backbone or DHCP relay at the access point network router to assign addresses to
wireless stations.
134

4.9 Deterministic Coverage
In order to achieve deterministic coverage, a static network must be deployed
according to a predefined shape. The predefined locations of the sensors can be
uniform in different areas of the sensor field or can be weighted to compensate for the
more critically monitored areas. An example of a uniform deterministic coverage is
the grid-based sensor deployment where nodes are located on the intersection points
of a grid. In this case, the problem of coverage of the sensor field reduces to the
problem of coverage of one cell and its neighborhood due to the symmetric and
periodic deployment scheme. [5]
An essential goal in wireless deployment is to ensure all areas are adequately
covered. The coverage of each wireless cell depends on the location of the access
point and the antenna used. Office spaces often have internal walls and obstacles and
are rarely circular. A careful plan is necessary to maximize coverage and performance
with the fewest possible access points and least susceptibility to co-channel
interference. Due to variability in the composition and thickness of building materials
the only guaranteed way of determining the cell coverage area of an access point is by
on-site measurement. However, there are some general guidelines that will help with
planning: [13]
a. In an open plan office such as those with cubicles, there should be little
attenuation of the radio signal. An 802.11b or 802.11g access point with an omni
directional antenna will provide a cell with radius of around 328ft/100m
(100ft/30m of this at maximum data rate). An 802.11a access point will cover an
area with an approximate radius of 164ft/50m (30ft/10m at the maximum data
rate). [13]
b. 2.4 GHz (802.11b and 11g) wireless signals will generally penetrate internal
walls although there may be some signal attenuation, especially if the walls are
made from cinderblock. It is worth noting that internal walls often have part-
metal construction and this can increase signal attenuation, too. [13]
c. 5 GHz (802.11a) signals do not penetrate interior walls well and this should be
taken into account when planning. [13]
d. In a multi-floor building, there may be some signal leakage between floors. For
example, an access point mounted midway between the floor and ceiling on the
second floor may radiate signals through to adjacent floors depending on the gain
and coverage of the antenna. This can be especially relevant for the floor above a
ceiling-mounted antenna. [13]
5 CONCLUSION
Colleges and universities are embracing wireless-networking technology with an
enthusiasm that gives new meaning to the term "academic freedom”. Wireless campus
networks require elegant deployment planning, analysis and design because every
faculty, centers has its own requirements. Wireless campus networks depend on
having a solid, stable, well-designed wired network in place. If the existing network is
not stable, chances are the wireless extension is doomed to instability as well.
135

Wireless communications must scale to meet universities demands, ensuring high
throughput, secure mobility, and a seamless integration with the wired network.
ACKNOWLEDGEMENT
This study is based on author’s experiences, observations and findings when studying
and working in few universities and companies since four years ago. With reviewing
some of wireless conference and white papers, a lot of useful ideas had been taken to
emerge a fundamental exercise for IT Managers/Engineers in universities in
deploying wireless communications in their campus. The author would also like to
thanks to all parties who give a generous and brilliant ideas in producing this paper.
REFERENCES
1. Shotsberger, P, G, Vetter, R, “Teaching and learning in the wireless classroom”, Computer,
Vol, No 34, March 2001, pp 110-111.
2. Holmes, A, Schmidt, K, J, “Do mobile and wireless technologies add value to higher
education”, In Proceedings of Frontiers in Education (FIE), Boston MA. Vol, No 1,
November 2002, pp 455-458.
3. J. Geier : WLAN Deployment Risks. White Paper, Wi-Fi Planet, USA, 2004.
4. “Designing WLANs”, White Paper, Trapeze Networks, USA, 2004.
5. Seapahn Meguerdichian, Farinaz Koushanfar, Miodrag Potkonjak, Mani B. Srivastava,
“Coverage Problems in Wireless Ad-hoc Sensor Networks”, Infocom 2001.
6. S. Arnesen and K . Haland, “Modeling o f Coverage in WLAN,” PhD Thesis , Agder Univ
ersity, 2001.
7. M. Haenggi, “Analysis and Design of Diversity Schemes for Ad Hoc Wireless Networks”,
IEEE Journal on Selected Areas in Communications, 2004. Accepted for publication.
8. Koo, S. G. M., Rosenberg, C., Chan, H. -H., and Lee, Y. C. , “Location Discovery in
Enterprise-based Wireless Networks: Implementation and Applications”, In Proceedings of
the 2nd IEEE Workshop on Applications and Services in Wireless Networks (ASWN
2002), Paris, France, Jul 3-5, 2002.
9. J. N. Laneman and G. W. Wornell, “Energy-Efficient Antenna Sharing and Relaying for
Wireless Networks”,' in Proc. IEEE Wireless Comm. and Networking Conf. (WCNC),
Chicago, IL, Sept. 2000.
10. V. Erceg et al, “Channel Models for Fixed Wireless Applications,” IEEE 802.16a standards
document, July 2001.
11. Maxim, M, Pollino, D, “Wireless Security”, 1st ed., McGraw-Hill/Osborne: pp.191-195.
12. Franklin, Tom, “Wireless Local Area Networks”, White Paper, TechLearn,.
13. “Deploying 802.11 Wireless LANs”, 3Com White Paper. www.3Com.com/wireless
136