Prakash Nair, RA
October 2002
uinns
Beach Primary School in Western Australia is a simple, unassuming campus.
Room designs maximize opportunities for students to mix and collaborate.
Spaces connect directly to outdoor learning and play areas that are usable
throughout the year. Students of various ages work on projects in groups,
creating a quiet buzz of activity. It is common to see older students
mentoring younger ones. Teachers move around to the students and groups
rather than being rooted to a lecturing spot.
Wireless laptops are a mainstay in this school, letting students compute
from nearly anywhere inside or outside the building. To support their
project work, students often access the Internet. They can print their
work wirelessly on one of several high-speed printers located throughout
the small campus. Electrical outlets are plentiful for times when laptop
batteries grow weak. Students with a need to move large files or use applications
that move large amounts of data across the network, such as video editing
or CAD (computer-aided design), can access desktop computers hardwired
to the school's local area network (LAN). These desktop computers constitute
about thirty percent of the school's computers.
In this school, technology compliments the idea that learning is something
personal that cannot be mass- produced, and that computers help students
build the confidence, curiosity, autonomy, and skill to pave their own
unique learning paths. Information technology—which reflects and
supports an economy based on knowledge and requires workers skillful in
using "knowledge tools"—is an integral part of this learning
environment. Best of all for the school's administrators and the community,
the Quinns Beach technology design was affordable enough to become reality.
Quinns Beach and schools in the United States, such as Rye Country Day
School in Rye, New York, exemplify an approach being taken by many school
districts to integrate computers logically and affordably into a school
building's infrastructure. With laptops and other smaller devices quickly
overtaking desktop computers in popularity, wireless networking's promise
to provide ubiquitous computing anywhere, anytime for these portable devices
is hard to ignore.
The local area networks that bring computers alive in school buildings
by providing connectivity between users and the Internet are sprouting
wireless segments at an increasing rate, and for good reasons. Foremost
among these are the freedom and simplicity of working without wires. In
older school facilities or portable classrooms, wireless offers a quick
way—sometimes the only practical way—to get students computing.
Author and educator Jamie McKenzie summarizes in the journal From Now
On why wireless networks utilizing mobile computers are preferable
to the still-prevalent practice of putting desktop machines in each classroom
(McKenzie 2001):
Ease of movement. Untethered laptops can be moved anywhere
in the building and require no special furniture.
Relaxed fit. Laptops are easier to accommodate within
existing classrooms because of their small size.
Strategic deployment. Laptop computers can be deployed
on rolling carts where they are needed most, creating one-to-one learning
opportunities that traditional methods of placing hardwired computers
throughout a school do not provide.
Flexibility. Laptops can be used within existing rooms
and can be configured to fit the teacher's preference and the nature of
the learning experience, whether it is team, group, or individual. Wireless
laptops place no additional demands on furniture or space.
Cleanliness. Elimination of cables and wires means that
twenty-five or even thirty laptops can be accommodated in a room without
creating clutter.
Low profile. Unlike desktops, behind whose large monitors
students may be hidden, laptops have low profiles and allow teachers and
students to make important eye contact.
Convenience. Wireless laptops' ability to be readily
available when needed and easily stowed when not makes them more likely
to be used. There is almost no setup time for wireless laptops. They can
be up and running without students needing to find and connect or disconnect
a wire (as would be required for hardwired network access) and without
students needing to move to a fixed computer workstation. This is a huge
advantage and another way in which the technology itself becomes subordinate
to the task of learning.
Simplicity. The simplicity, comfort, and reliability
of wireless laptops means that teachers and students can focus on learning,
not on hardware. This helps technology attain the use that has been hoped
for but not often realized because of technical difficulties or inconvenience.
A wireless local area network (WLAN) is actually nothing more than an
invisible extension of the visible hardwired network most schools already
have. The wireless links in a wireless network are made possible by two
key sets of components: access points and wireless network adapters. Access
points are radio transceivers operating on one or more frequencies and
acting like satellites to send, receive, and manage information from all
the computers and devices in the network. Wireless network adapters are
radio transceivers housed within each computer that establish communications
with the access points. Signals from an access point can travel roughly
800 feet outdoors and considerably further with add-on antennas. Their
efficacy indoors varies depending on obstructions, the number of users,
and the industry standard they are based on.
WLAN performance has been shaped by a family of standards under the 802.11
designation developed by the Institute of Electrical and Electronics Engineers,
Inc. (IEEE). Interoperability between products is verified by the Wireless
Ethernet Compatibility Alliance, which grants the use of its Wi-Fi (wireless
fidelity) logo to products that pass its tests. The IEEE 802.11b standard,
a mainstay of WLAN development since 1999, and the soon-to-be-ratified
802.11g standard (see Appendix One for a comparative analysis), permit
access points to transmit over one of three specific channels or frequencies.
This means that, within a given zone, up to three access points can be
installed, each transmitting on a different channel, with the wireless
network adapters inside computers constantly sampling the three channels
and locking onto the one offering the best performance. With the IEEE
802.11a standard, which offers advanced capabilities over the 802.11b
standard (despite its "a" designation), access points can be
set to operate on one of eight discreet channels, with up to eight access
points deployed in a coverage area or zone, such as an auditorium, where
many users might be accessing the network. This is important because,
as with wired networks, the bandwidth available in a given area is shared—that
is, the more users "drawing" from a specific access point in
a given area, the slower the wireless connection. Adding additional access
points to a given area increases the bandwidth available and the performance
for users.
Wireless computing's potential to revolutionize technology access in schools
became evident soon after the first edition of IEEE 802.11 was published
in 1997. Writing for Schoolhouse Journal about the technology's
potential, architect and facilities planner Ed Kirkbride noted, "Wireless
laptop computers reduce the need for and costs of technology cabling and
additional electrical power and wiring, and they reduce the disturbance
to existing construction as well as the environmental hazards and costs
for remediation of asbestos and lead paint" (Kirkbride 1999). Wireless
technology enables every school, new or old, to provide networked computing.
Despite its promise, the early adoption of wireless networking was not
widespread. Concerns included high costs, bandwidth, interference, security,
safety, reliability, and longevity. This next section provides an update
of advances, developments, and concerns in seven key wireless areas:
Bandwidth. As discovered by the millions of home users
who have migrated from 56 kb/s modems to broadband DSL or cable connections,
higher bandwidth means less waiting while your computer accesses information
from somewhere else.
When wireless networking was first introduced into schools, the 1 or 2
Mb/s data transmission rate that the first iteration of the IEEE 802.11
standard offered was a limiting factor. The available bandwidth of an
access point, analogous to water in a pipe, could be diluted beyond ideal
quantities, particularly when users simultaneously browsed websites, opened
large files, or worked with multimedia applications. That problem was
lessened with the IEEE 802.11b standard, which delivered about 7 Mb/s
of a promised 11 Mb/s transmission rate to a single user. Remember that
this is shared bandwidth; the more users that are connected and actively
using the system, the less bandwidth available to each user.
According to Charles Bartel, director of computing services at Carnegie
Mellon University and a pioneer of campus-wide wireless implementations,
the typical user seems to be satisfied with a network speed of about 1.5
Mb/s, which is about the speed offered by a T1 line. Bartel believes that
this speed can be achieved with about one wireless access point per classroom
using a network based on the 802.11b technology (CMU.edu 2000). The adequacy
of this speed is predicated upon the kind of staggered access that enables
workers in large offices to share a single T1 line without experiencing
bandwidth logjams—because users are performing different tasks at
different times. In schools, bandwidth logjams with wireless systems can
similarly be mitigated when computers are used in conjunction with individualized
instruction, where students perform different tasks at different times
and rarely access large files simultaneously from the school network or
Internet.
Even with staggered access, Quinns Beach and other schools with the 802.11b
technology have discovered that higher bandwidth activities like transmitting
large files and viewing full-motion video from a DVD player can overtax
their systems. Newer standards, such as the 54 Mb/s system created by
the IEEE 802.11a and draft 802.11g standards, are helping to meet demand
for increased bandwidth.
From a technological standpoint, wireless networks won't likely supplant
the speed advantage of wired Ethernet networks; moreover, high-performance
desktop computers operating on wired networks for specialized applications
such as CAD and video editing still will be needed. But more and more
applications in schools can and will happen wirelessly, and wireless networks
will flourish, particularly hybrid systems that utilize wired backbones
offering a mixture of wired and wireless segments.
Interference. With wireless products crowding the 2.4
GHz frequency on which they operate, WLAN technologies operating under
the IEEE 802.11b and draft 802.11g standards will have to cope with interference.
Wireless signals will not penetrate through metals and other materials
that reflect or absorb them, such as objects with a high water content.
Even people can affect transmission rates. According to Howard Strauss,
technology coordinator for the Corporation for Research and Educational
Networking (CREN) Tech Talk series, "To a microwave oven, cordless
phone or wireless LAN, you are very close to being just a five- or six-foot
mobile column of water, absorbing radiation that was intended for cooking
or communication" (CREN.net 2000). The net effect of interference
is not that data is lost but that the system slows down. Interference
can be minimized by the careful siting and installation of access points
and, in the case of new construction, the design of the building itself.
System design and layout. To create a wireless-friendly
building or campus requires collaboration between WLAN designers and architects
early in the planning and design process. The number of wireless devices
greatly affects system design, layout, and cost, with larger systems presenting
many more challenges. "The best approach," Bartel (2000) advises,
is to predetermine spaces that will have a large number of users, such as large group instruction areas and libraries, that could benefit from additional access points. You also must determine the areas, such as offices, that need to have fail-safe service and might better utilize hardwired connections. Budget constraints may dictate that there be areas where a best-effort coverage is acceptable.
Bartel suggests that
the best design will come from a site survey that includes deploying access
points through an interactive process of sample testing, rough layout
testing, mapping the layout on paper with color-coded coverage patterns,
then retesting to find the best compromise between coverage and capacity.
Testing is done with an RF (radio frequency) test unit during normal hours
to include potential "interferers" as part of the testing process.
A fully occupied space will test differently than one that is empty or
being tested at times other than normal hours. Designing a good WLAN requires
a little "art" along with science and often a bit of tweaking
after the initial installation to get optimum results.
Access points must be carefully located so that users who go beyond the
range of one access point will be switched automatically to the next without
encountering dead zones where signals are too weak. Dead zones can also
occur because of the presence of metals or competing signals from devices
such as microwave ovens, although microwave ovens built to newer specifications
no longer pose a problem.
By providing an adequate number of strategically placed access points,
a good design can reduce significant bandwidth loss caused by too many
people online or by people venturing too far from an access point or getting
too close to more than one access point broadcasting on the same channel.
Security. Since wireless signals use radio waves, there
is always the danger that unauthorized users can tap into a wireless system
more easily than a wired one. But reports of security problems from schools
using WLAN technology are not widespread, and today's wireless standards
offer greater security than earlier versions.
Present wireless security technology, also called wired equivalent privacy
(WEP), offers two levels of encryption: 40 bit and 128 bit, with 128-bit
encryption recommended for applications where greater security is needed.
The trade-off is that higher encryption levels slow down the system, though
not to the point where today's high-speed systems lose significant functionality.
The objective of WEP is to provide security similar to wired networks.
Of course, wired networks have their own security vulnerabilities. For
example, in many schools, it is easy to walk into a public space and connect
a laptop to a jack with no questions asked.
Encrypting signals that traverse the wireless link itself is just one
of several layers of security that a school may provide for its computer
networks. Other appropriate security methods, such as password authentication,
firewalls, and virtual private network solutions, can greatly reduce security
risks for users and for WLAN-based resources (Nair 2001).
Network administration. Network administrators will find
WLAN networks harder to operate, manage, and secure on a daily basis than
wired networks because user mobility means that there is less predictability
about which parts of the network will be more loaded than others at given
times. Jeff Spain, network administrator at Cincinnati Country Day School,
notes that one problem he has with wireless is that he cannot apply quality
of service controls (QOS) to the wireless access point. QOS in a hardwired
network lets users make changes on the fly to optimize performance and
get instant feedback from users' computers—something that wireless
networks do not yet allow.
Occupant health. Studies about potential WLAN health
risks do not find a compelling danger posed by the electromagnetic radiation
from WLAN equipment. The Wireless Networking Industry's Information Source
summarizes the issue (WLANA 2000), noting:
The interpretation of more than four decades of research in this area has led to a scientific consensus on the safety of exposure to radio-frequency electromagnetic fields. This consensus is reflected in the recommendations and standards developed by committees such as the National Council on Radiation Protection and Measurements Scientific Committee 53, IEEE Standards Coordinating Committee 28, International Radiation Protection Association/International Non-Ionizing Radiation Committee, and National Radiological Protection Board. Manufacturers of wireless networking products design them to operate within the guidelines of these standards and recommendations and, therefore, [the products] are considered safe.
Technology consultant
Keith Lightbody suggests that it is important to consider the level of
radiation in the school environment, given that students are in school
for about 12,000 hours of their lives. Electromagnetic radiation is emitted
by many familiar devices, including computers, cordless phones, microwave
ovens, and fax machines. For purposes of comparison, Lightbody provides
the following chart that ranks radio emissions from WLAN systems and other
devices encountered in daily life:
|
| Wireless access point 30 mW |
| Mobile (cellular) 600 mW |
| Mobile (cellular) phone car kit 3,000 mW |
| (mW = milliwatt, one thousandth of a watt) |
In a study conducted
at Quinns Beach Primary School and Seven Oaks Senior College, in Perth,
Western Australia, Lightbody noted that the wireless networking equipment
used in these schools has radiation levels 400 times lower than the limit
specified in Australian standards.
Vandalism. With schools' increased expenditures for high-technology
equipment and infrastructure, the potential for vandalism requires careful
consideration. As aptly reported in Education Week, "These
days, a single case of vandalism can carry an especially hefty price tag—thanks
to increased presence of computers, telecommunications devices, broadcasting
and recording equipment, and other expensive technology on school campuses
(Bowman 2002)." The extent to which a WLAN system is susceptible
to vandalism depends on how it is deployed. The most common type of installation
in schools is the rolling cart, where the wireless access point is contained
within the cart, and safety depends on how securely the cart is stored
after hours. Another typical installation is an add-on system, where wireless
transceivers or access points are plugged into existing network connections
to extend the reach of the wired network. These add-on systems are vulnerable
to vandalism because the access points are often placed in visible locations,
as are other devices such as extender antennas, which literally extend
the reach and strength of signals to and from an access point. Such devices
can be easily detached and stolen, and building owners are beginning to
enclose them in protective cages to prevent loss. A third common type
of wireless installation is the integrated system, where the wireless
infrastructure is installed when the building is constructed—though
such an integrated approach is also possible in retrofit situations. In
these cases, access points can be hidden from view within ceiling plenums
and connected to invisible extender antennas integrated into the ceiling
systems. At least one manufacturer (Armstrong Industries) now offers wireless
extender antennas disguised to look like ceiling tiles. Under this scheme,
no part of the wireless infrastructure is visible to building users.
WLANs offer some advantages that reduce the possibility of vandalism while
improving functionality. For example, schools can install brackets that
permit the easy installation and removal of data projectors. This is more
realistic for projectors that come wireless-ready, because wireless projectors
reduce the time and expense of setup and takedown and can be installed
anywhere. The improved functionality derives from the fact that students
and staff can easily "beam" their signals from untethered laptops
to data projectors via the WLAN. This not only speeds up connection time
but also means that presenters can be located anywhere in the room and
not be hostage to a location dictated by the reach of cables required
to connect their laptop to the projector.
Wireless computing is changing many traditional learning environments
because of its reach and convenience. Higher education campuses, the earliest
WLAN users, have documented WLAN's effects on student learning and behavior.
As noted by Educause (2002), a nonprofit association dedicated to advancing
higher education by promoting the intelligent use of information technology,
Students entering higher education in the next few years may take for granted the idea of a wireless campus—a place [where] they may never have to worry about finding a phone jack or a data line to connect to the school's network. They will have the ability to use their laptops and handheld devices—whether to e-mail a paper, do library research, or participate in a class online discussion—anywhere on campus, without having to worry about physically plugging in their hardware.
Beth Blackwood, principal of the K 12 Presbyterian Ladies College in Perth, Western Australia, says WLAN technology has absolutely changed the way her teachers teach and her students learn:
Prior to wireless, it was very difficult to access information online. Each classroom was networked, but at best we could only daisy-chain a few laptops at a time from the connection. It is now possible for 600 students to access e-mail and the Internet across the campus. Since wireless networking, there has been a proliferation of teachers designing digital curriculums—using links, the intranet, and the Internet—and seeking to have queries and assignments e-mailed to them.
When asked if students connected to the network or Internet from locations other than their classroom, Blackwood replied,
The students access the network across the campus. It is not unusual to see the girls using their laptops on the grounds after school while they are waiting to be picked up by their parents. They utilize the laptops in the boardinghouse, at sports for recording trials and scores, and at recess and lunchtimes. None of this was possible before wireless. We have a student who lives directly across the street from the school. I often see her sitting on the sidewalk outside her house with her iBook® on a weekend or early evening—the sidewalk is close enough to access our wireless network.
Educators like Blackwood
are seeing the liberating power of the wireless network, understanding
how it represents a culture change. As author Terian Tyre notes, "WLAN
technology also uniquely enables ad-hoc networks. These may be quickly
set up in standalone, peer-to-peer mode, with or without a connection
to the school or district LAN. Teacher training, student workgroups, PTA
nights, science fairs, and board meetings, to name just a few examples,
could all benefit from such on-the-fly connectivity."
Though some believe WLANs are more an add-on technology than a factor
necessary for the conceptualization and design of school facilities, it
is easy to envision WLANs in a variety of roles. WLAN technology offers
great flexibility and functionality in retrofit situations as well as
an excellent complement to learner-centered design features that some
schools are adopting. A few examples include (Nair 2002):
Learning studios. Multipurpose learning studios, where
different children can engage in different tasks in various activity zones
or areas, would benefit greatly from a WLAN. Unlike a scheme requiring
each computer to be tethered to a network with wires, the wireless approach
is unobtrusive, complementing the idea of personalized learning.
Kivas, atriums, and "learning streets" instead of corridors.
The value of these kinds of informal places that stimulate social interaction
and learning is greatly enhanced by the ready accessibility to the world
of information that mobile students can attain via a WLAN.
Resource areas. WLAN technology can readily deliver the
resources that help maximize the utility of the school library, media
center, cafeteria, and fitness center as learning areas that students
can use as they see fit—not on some predetermined schedule as may
be required in a computer laboratory. With WLAN technology, all of these
areas and others can easily serve as formal and informal learning laboratories.
Unfettered access. Wireless technology will be an important
part of the student and teacher empowering process. Once students get
used to the idea of ubiquitous access to the Internet, the school intranet,
and to each other from any location in the school, it is more likely that
they will want to continue such access outside school. Having their own
portable computing devices will help foster that kind of anytime, anywhere
learning, which can continue at home, where students and teachers can
talk to each other by e-mail as well as by audio and video chat sessions.
Living, not static, architecture. Wherever maximum flexibility
for change is desired, which includes having the ability to rearrange
spaces, move walls, as well as furniture and equipment to create a variety
of teaching environments, WLAN technology provides the maximum amount
of flexibility from the perspective of electronic communications and student
access to information.
According to Scott Carlson (2000), "The technology is good for the
bottom line. Wireless technology often is less expensive than standard
wire-and-wall-jack installation. In older buildings, wireless access may
cost only a fifth of what an institution would spend on standard hookups."
In some cases, universities have actually equipped desktop computers with
wireless access because of its convenience at a reasonable cost. The computers
can be rolled out into lobbies and common areas and be used for student
registrations and other temporary tasks requiring network access. While
K 12 needs are somewhat different, there is no question that wired systems
that try to create the ubiquitous computing environment permitted by wireless
technology will be substantially more expensive.
One benefit of wireless that often goes unnoticed is its ability to connect
portable classrooms with the school network and the Internet. By beaming
signals wirelessly to these temporary units, schools save the cost of
wiring these buildings. Many school districts have chosen to leave their
portables unwired, creating a situation of technology haves and have-nots.
By extending both network and Internet connections to the portables by
wireless means, schools can ensure that equitable technology access is
available to all. Thousands of portable classrooms can benefit in this
manner.
In the future, more schools will be designed with the understanding that
learning does not begin or end within the classroom. Wireless devices
are but one means of freeing teaching and learning from the confines of
the classroom and making education truly an anywhere,
anytime enterprise.
The question for educators contemplating investments in technology is
not so much whether wireless is a good option but how to make it an effective
tool in the creation of student-centered learning environments. This means
thinking about ways in which to integrate wireless solutions into the
overall scheme of learning.
Today, wireless systems no longer are experimental or risky. In fact,
a well-designed wireless network represents a good measure of "future
proofing" a facility. It allows the next generation of handheld devices,
tablet computers, high-powered laptops, data projectors, printers, scanners,
video cameras, and various other WLAN-compliant devices to connect to
the network and each other while giving administrators, teachers, and
students a greater measure of freedom and flexibility. In this fast-changing
technological world, wireless systems will play an increasingly vital
role.
LAN. Local area network. A communications network of
computers or other electronic equipment in a local area such as a school
or office.
MAN. Metropolitan area network. A communications
network designed for a city or town that is larger than a local area network
but smaller than a wide area network.
WAN. Wide area network. A communications network utilizing
devices such as telephone lines, satellite dishes, antennas, and microwaves
to span a larger geographic area than can be covered by a local or metropolitan
area network.
WLAN. Wireless local area network. The extension of a
wired LAN (see LAN) through radio transmissions to permit mobile users
to connect their laptop computers or other wireless-enabled digital devices
to a LAN.
WWAN. Wireless wide area network. A wide area network
that uses wireless radio signals to connect two or more LANs located within
different buildings.
kb/s. Kilobits (one thousand bits) per second.
Mb/s. Megabits (one million bits) per second; one thousand
times faster than a kb/s.
Gb/s. Gigabits (one billion bits) per second; one million
times faster than a kb/s.access point. An antenna that transmits and receives
signals over the airwaves and thereby serves as the interface between
a wired network and wireless LAN adapters installed in laptop computers
or other wireless devices (see definition for wireless network adapters).
backbone. The principal or main transmission line in
a network that carries data gathered from smaller wires or cables that
interconnect with it.
bandwidth. The amount of data that can pass along a communications
channel in a given time period.
bit. A unit of information that has the value 0 or 1;
short for binary digit.
byte. A unit of information comprising eight bits, generally
used to signify a letter of the alphabet.
CAD. Computer-aided design. A hardware and software system
that permits its users to automate the development of design representations,
drawings, and related documents. CAD systems require high-definition monitors,
powerful processors, and other special equipment.
encryption. Use of code to obscure communications. The
numbers, such as 128- or 40-bit encryption, refer to the size of the key
used to encrypt the message. Encryption with a 128-bit key requires many
times more computer power to decipher than encryption with a 40-bit key.
Ethernet. A popular apparatus for enabling communications
between two or more computers over a communications cable. Ethernet supports
data transfer rates of 10 Mb/s. Fast Ethernet, a newer version, supports
transfer rates of 100 Mb/s. Evolving 10 Gigabit Ethernet systems support
transfer rates of 10,000 Mb/s. Faster systems are being developed.
fiber optic cable. A thin strand of very pure glass covered
in plastic developed to supercede the use of copper cable for transmitting
great quantities of information encoded as pulses of laser light.
firewall. A security plan intended to prevent unauthorized
users from accessing a computer network.
GHz. A unit of electromagnetic wave frequency equal to
one thousand million hertz (1,000,000,000 Hz). The gigahertz is used as
an indicator of the frequency of ultra-high-frequency microwave signals.
hardwire. To connect (computer components, for example)
by electrical wires or cables.
IEEE. Institute of Electrical and Electronic Engineers,
Inc., an international standards organization.
interoperability. The harmonious working together of
different types of computer hardware and software.
PDA. Personal digital assistant. A handheld computer
that can upload and download information from a desktop computer and other
devices. Some PDAs have wireless capability and also can access the Internet.
T1. A leased telephone connection popular with businesses
and schools for connecting to the Internet. Provides data transmission
rates of 1.544 million bits per second (1.5 Mb/s).
virtual private network. A private network that uses
the Internet to connect remote sites or users while utilizing advanced
security techniques to create secure communications.
WEP. Wired equivalent privacy, a data privacy mechanism
for wireless networks described in the IEEE 802.11 standards. Its purpose
is to simulate in wireless networks the same security features of a wired
network.
wireless network. The extension of a LAN or WAN without
wiring so that devices equipped with wireless network adapters can communicate
with the wired network via the airwaves.
wireless network adapters. Electronic devices in laptop
computers, notebook computers, and handheld devices that give users the
ability to move freely within a campus or building environment while maintaining
an uninterrupted connection to a network (also see access point).
| Standard: | Bandwidth: | Advantages: | Disadvantages: | Comments: |
| IEEE 802.11 (1997) |
1
Mb/s to 2 Mb/s |
This standard is effectively obsolete, but it paved the way for the standards that followed. | Early wireless adapters for computers were expensive; security was a problem. | Bandwidth limitations did not allow widespread use in schools. |
| 802.11b (1999) Bandwidth |
5
Mb/s to 11 Mb/s |
Provides
sufficient bandwidth to satisfy a majority of applications in schools. Improved security. Products available from multiple vendors. Interoperability assurance between products offered by Wireless Ethernet Compatability Alliance. Can be less expensive than wired systems, particularly for older or historic buildings. Good outside range (about 800 feet); permits campus-wide installations. Transmissions automatically switch among one of three channels. |
Potential
interference from other products such as microwaves, cordless phones,
and Bluetooth devices that operate on the unlicensed 2.4 GHz frequency
band. Effective bandwidth is usually only 7 Mb/s, not sufficient for bandwidth-hungry applications such as video conferencing and DVD transmissions. Effectiveness is reduced in densely populated areas that have hundreds of users, such as school auditoriums. |
802.11b is a widely accepted standard that most schools are satisfied with both for indoor and campus-wide applications. |
| Standard: | Bandwidth: | Advantages: | Disadvantages: | Comments: |
| IEEE 802.11a (1999) |
54 Mb/s | Supports
the transmission of video, voice, and other large files. Transmissions in the 5 GHz band ensure lack of interference from a host of devices such as cordless phones that share the 2.4 GHz frequency. Works well in densely populated areas because eight-channel operability means more access points can be deployed within the same space than with an 802.11b system. In some configurations, bandwidth of up to 108 Mb/s may be achievable. Speed decreases with increased distance at a lesser rate than with 802.11b systems. This means, as a user gets farther from an access point, an 802.11a access point will still deliver up to 12 Mb/s, whereas the 802.11b system delivers just 2 Mb/s. |
Not
backward compatible with existing 802.11b systems. This means that
schools significantly invested in 802.11b technology should think
carefully before migrating to the 802.11a standard. However, there
are indications that dual compatibility access points may soon be
offered, effectively eliminating this disadvantage. Prices for 802.11a access points and peripherals will be higher in the short run. Effective range of 5 GHz systems is less than 2.4 GHz systems. This means more 802.11a access points will be needed to cover the same area than 802.11b access points. This is an issue that is more relevant to large campus settings. Lower range means that 802.11a systems will be more costly to install, though users will benefit from the higher bandwidth these systems offer. Most 802.11a access points do not permit the use of replacement antennas. Some of the frequencies used by 802.11a devices are not licensed for outdoor use. |
In
the long run, there seems little question that the newer, higher bandwidth
802.11a and draft 802.11g standards (see below) have many advantages
over the older 802.11b standard. Dual-compatibility systems will also
probably hasten the demise of 802.11b systems — particularly
in the K 12 market, which is not already heavily invested in the older
standard. It is hard to tell which of the two newer standards, 802.11a or 802.11g, will prevail in the long run or if they will coexist. In any event, it would appear that schools choosing either standard can avail themselves of the full benefits of high-speed mobile computing. |
| Standard: | Bandwidth: | Advantages: | Disadvantages: | Comments: |
| IEEE 802.11g (draft) |
54 Mb/s | Essentially,
this is similar to the 802.11b standard because it operates on the
2.4 GHz frequency band. All the advantages noted previously for the 802.11b standard apply. The 802.11g standard is backward compatible with the older 802.11b standard that many users are heavily invested in. This standard can compete more effectively with the 802.11a standard because it offers the same higher 54 Mb/s bandwidth. Offers greater range than the 802.11a standard, which means larger installations will be less expensive than for the 802.11a standard. |
Not
a standard yet. 802.11g products may require upgrades when the standard
is released. Potential interference from other products such as microwaves, cordless phones, and Bluetooth devices that operate in the unlicensed 2.4 GHz band. Potential to increase bandwidth to 108 Mb/s (as with the 802.11a standard) has not been demonstrated. |
See previous comments. |
| Wireless technology
is now sufficiently mature that its use in schools is becoming common.
The technology owes its development to the advance of standards that
enable the marketplace to produce interoperable wireless products
and equipment. As the following discussion about Bluetooth and 3G
(third generation) illustrates, there are some areas of overlap between
these standards and WLAN technology based on the IEEE 802.11 family
of standards. All indications are that over the next several years,
Bluetooth, 3G, and 802.11 standards will coexist. WLAN designs for
schools should not be significantly affected by the emergence of Bluetooth
and 3G. What Is Bluetooth? Essentially, Bluetooth is a cable replacement technology in the form of a standard specification that permits electronic devices such as camcorders, PDAs, and computers to establish a wireless link for convenient data exchange. A typical application would be to walk up to a printer and beam the document you want printed directly from your laptop. The Bluetooth standard is supported by the Bluetooth Special Interest Group, a trade association with more than 2,000 members, including IBM, Intel, Microsoft, and Nokia. Bluetooth-equipped devices transmit data to each other within a 30-foot distance at about 1 or 2 Mb/s utilizing the 2.4 GHz frequency band. This is the same band on which the IEEE 802.11b wireless systems operate, posing the potential for signals to interfere with each other, though technologies currently exist to minimize such interference. Bluetooth devices also may beam signals to each other to create what is sometimes called a "personal area network," though such a network cannot offer the robust operations provided by networks based on the IEEE 802.11 family of standards. At the present time, schools should not do anything different when it comes to designing their IEEE 802.11 networks to accommodate Bluetooth technology. At some future date, when and if all computers and peripherals are Bluetooth-compatible, students may choose to access desktop computers or other devices such as printers and scanners directly from their laptops, PDAs, or cell-phones, rather than through a network based on one of the IEEE 802.11 standards. What Is 3G? 3G is the technology that is going to bring high-bandwidth applications to your cell phone, PDA, and other wireless-enabled digital devices such as tablet computers. The advantage of 3G over the IEEE 802.11 standards and Bluetooth is that it will provide truly ubiquitous wireless access. This means that a 3G device will keep you in touch with the Internet and all your information anywhere you go, not just within a building or campus that is wired for WLAN. While still several years away from being fully implemented in the United States, 3G devices will eventually access data at the rate of about 2 or 3 Mb/s. The huge sums of money being invested in the development and rollout of 3G networks means that access will not be cheap, and users probably will try to access their information in other ways, such as by getting within the range of existing WLAN networks that are proliferating in schools, airports, and shopping centers. Despite competition from WLAN, 3G is expected to be adopted and accessed widely in the United States by 2006. In the meantime, the use of Internet-accessible phones and PDAs operating at lower bandwidths continues to grow exponentially. For schools contemplating wireless, 3G is not likely to be an important factor in the design scheme for at least the next several years. Yet because planning requires foresight, looking ahead at these technologies is a good idea. |
|
|
||
| Year | Students Per Computer | Students Per Multimedia Computer |
| 1992 | 18 | |
| 1993 | 16 | |
| 1994 | 14 | |
| 1995 | 12 | |
| 1996 | 10 | |
| 1997 | 7.3 | 21.2 |
| 1998 | 6.3 | 13.5 |
| 1999 | 5.7 | 9.8 |
| 2000 | 5 | 7.9 |
| 2001 | 4.2 | 6.9 |
| Sources: Market Data Retrieval, Quality Education Data, and NoteSys, LLC [NoteSys ceased business operations.] | ||
The goal of many educators is to have each student possess a multimedia-capable laptop computer so that, at any given time, all students in a selected location can be working on a laptop. Classrooms that have four or five fully multimedia computers do not make this possible. |
||
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Prakash Nair, RA, REFP, is an international school planning consultant and architect. He is president of Urban Educational Facilities for the 21st Century and principal of Prakash Nair Consulting. He can be reached at prakash@designshare.com.
The author thanks Keith Lightbody for his help and guidance with the preparation of this publication.
Ed Brzezowski, Eric Flack, Walter Horowitz, Glenn Meeks, Chuck Philips, Andrew Seybold.
Published by the National Clearinghouse for Educational Facilities (NCEF), an affiliate clearinghouse of the Educational Resources Information Center (ERIC) of the U.S. Department of Education. 2002 by the National Clearinghouse for Educational Facilities.
All rights reserved.
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