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February 2001
Proven and Promising Mobile Technologies
by Lowell Rapaport
More than 1.4 billion people will access the Internet wirelessly by
2004, according to Cahners In-Stat Group. In this promise, many see the
makings of a whole new platform for business computing. A new generation
of handheld computers, mobile phones and laptops will empower mobile
executives, sales people, service people and customers who are ready to
do business wherever they may be.
Today, digital wireless communication is in its infancy, and
bandwidth limitations keep applications quite simple. For example,
wireless Internet access from cell phones is largely confined to email,
text messaging and text-only Web surfing. Wireless local area network
(LAN) applications are more robust because they are based on mature
technology.
The major limiting factors on wireless data communications are range
and bandwidth. Range limitations can be mitigated somewhat by using
higher-frequency radio communications and by enabling roaming, the
ability for communications to a wireless device to be handed off from
one stationary transmitter to another. Roaming is a necessary feature of
cell phone networks and is beginning to be made available to wireless
LANs through HiperLAN (High-Performance Radio Local Area Network)
technology.
Even when roaming is supported, range is still important to LANs.
Longer-range devices permit greater freedom of movement, improve
communication through obstacles like building walls, and permit mobile
station operations where the LAN itself can be made portable.
Bandwidth limitations are improving as more efficient wireless
protocols and better-quality technology becomes available. Just as
ordinary wired networks get faster as Ethernet cable improves, wireless
networks get faster as they are assigned more bandwidth and as data
compression becomes more efficient.
The ultimate in mobile wireless communications will combine a
long-range portable LAN with shared wireless broadband access to the
Internet. With this combination, a powerful server could be installed on
a vehicle and made available to several users conducting field
operations.
One application for this wireless architecture would be to provide
Internet access to passengers on a moving vehicle, such as an aircraft
or train. Another would be to provide remote access to mobile work
teams, such as the doctors and nurses of the Children's Hospital of
Greenville, SC, featured in "Medicine Goes Mobile," page 47. This
medical-records application employs a mobile LAN, but current range and
bandwidth restrictions necessitate daily synchronization of a van-based
server rather than continuous connectivity.
An alternative architecture lies in the development of more powerful
handheld devices. As the bandwidth limitations on cell phone networks
ease, handheld devices can mature in two directions. They can become
more capable devices, able to run a wider array of applications and
supporting more elaborate user interfaces. At the same time, they'll
become "thinner" in terms of processing, relying more on remote servers
for data storage and server-side processing.
In such an environment, a handheld computer could trade away memory
capacity for processing power and battery endurance; a high-speed
wireless network makes it unnecessary to store data on the device
itself.
This approach would bring a next-generation advance to applications
such as the McKessonHBOC/AvantGo paperless proof-of-delivery application
featured in "Mobile Commerce: Moving From Paperless to Wireless," page
40.
McKesson is empowering drivers by packing shipping manifests, driving
directions, barcode scanning and signature capture into handheld
computers based on the Palm operating system. Current bandwidth and
range restrictions make wireless access impractical, so the mobile
devices are synchronized with the server at the beginning and end of
each workday.
Before more capable devices can be developed, wireless technologies
will have to deliver more reliable, higher-speed, longer-range
networking. Detailed below is a review of the existing and anticipated
technologies. They range from simple point-to-point communications to
long-range digital phone networks. With the exception of infrared, all
wireless communication technologies listed below use radio waves.
Infrared
One of the most ubiquitous wireless technologies, infrared has been
widely deployed on portable computers, handheld devices and printers
(though their infrared ports often go unused). Most people are familiar
with infrared technology since it is widely used by handheld remote
controls. Infrared waves occupy the frequency and wavelength band just
below that of visible red light.
The infrared protocol used for exchanging computer data is IrDA
(Infrared Data Association). IrDA has a communication speed roughly
equal to that of a parallel port or universal serial bus - about 1.2
megabytes to 1.5 megabytes per second. This is more than fast enough for
Web and Internet access. However, infrared has serious limitations. It
has an effective range of just 3 feet to 6 feet and can only communicate
over direct line-of-sight. This means that infrared connections are only
practical for short-term connection applications like synchronizing a
handheld computer with a database or quickly printing out a file.
Another familiar application used frequently at trade shows is to "sync
up" two handheld computers to transfer product information from a
company representative to a prospective customer.
IrDA users at least have relatively high security for a wireless
protocol. The short range and line-of-sight restrictions mean it is
highly unlikely that infrared communications will be intercepted.
Wireless Ethernet
Wireless Ethernet has been around for more than 10 years, but only
within the last two years has it become fast enough to be practical.
Wireless Ethernet is available in two protocols. The original protocol,
802.11, supports communication speeds of 1.6 megabits per second. This
is roughly equivalent to 200 kilobytes per second or the speed of a 1X
CD-ROM drive.
It is the newer protocol, 802.11b, that has made Wireless Ethernet
practical; it supports a full 11 megabits per second, a little faster
than 10BaseT Ethernet's 10 megabits per second. A third, even faster
protocol, 802.11a, has been specified, but as yet there are no suppliers
of 802.11a equipment.
Wireless Ethernet can be used anywhere 10BaseT or 100BaseT Ethernet
can be used, including offices, warehouses, campuses and even private
homes. Wireless network interface cards cost about $100 per computer and
wireless hubs about $300. The wired alternative can cost as little as
one-tenth as much, but then again, wireless Ethernet users save on the
cost of Category 5 cable and installation.
Any device capable of supporting a network interface card (NIC) can
use wireless Ethernet. This includes portable and desktop computers,
handheld computers and even network attached devices. The range of a
wireless Ethernet hub is about 150 feet, and roaming from one hub to
another is not supported. Wireless Ethernet is used for data and file
transfers and any other LAN communication. Wireless Ethernet equipment
is available from a number of network equipment manufacturers, including
Lucent, Murray Hill, NJ, and 3Com, Santa Clara, CA.
Bluetooth
One of the newest wireless connectivity technologies, Bluetooth, was
originally designed to allow cell phones to connect to accessories
without plaguing users with a nest of cables. The technology is being
adapted to a wide range of devices and applications. Bluetooth
technology is still in the developmental stage, and it will be some time
before the devices become widely available.
Bluetooth has a range of about 30 feet, though there is a version
with a range of up to 300 feet. The bit rate is between 1.0 megabits and
2.0 megabits per second - comparable to infrared or 802.11 connections.
It is sufficiently fast for Web surfing and for transferring audio
signals.
Since Bluetooth was originally designed to connect cell phones with
accessories, it demands little power. Bluetooth transmitters will be
able to detect the signal strength when connecting to a Bluetooth
device. If the signal strength is strong, the transmitter reduces power
to save battery life. Battery-operated devices like laptop and handheld
computers, cell phones and portable printers are expected to be the
first devices to take advantage of this technology.
Many Bluetooth products are on the verge of introduction. Expect
peripheral products, access points, and network routers that bridge LANs
and Bluetooth devices to debut this year. Some of these products are
already available from Ericsson, Richardson, TX, the cell phone
manufacturer and inventor of Bluetooth.
High-Performance Radio LAN
HiperLAN is intended to compete with and replace 802.11 networks
because of a number of advantages. With a sustained throughput of up to
20 megabits per second, HiperLAN is nearly twice as fast as 802.11b
Ethernet. The range of an individual HiperLAN access point is up to 450
feet, though this is not critical since the technology supports roaming.
With 802.11, you can't move from one wireless hub (called an access
point) to another without either logging off the network and
reconnecting, or just losing contact. HiperLAN automatically transfers
you from one access point to the next as you move through the network's
service area, just as a cell phone keeps you connected as you move from
one cell phone transmitter to the next.
HiperLAN's advantages make it a superior technology to 802.11 for
sprawling colleges, medical facilities, office complexes and factories.
It can be used for any type of communications normally conducted on a
wired LAN - file transfer, Web surfing, email, etc. Products based on
HiperLAN1, a slower version of the HiperLAN protocol, are available from
vendors such as Proxim, Sunnyvale, CA.
Cellular Technologies
There are three common types of cellular networks that employ two
approaches to data communication. Code Division Multiple Access (CDMA)
and Global System for Mobile Communication (GSM) are voice networks that
can be made to carry data. Cellular Digital Packet Data (CDPD) is a pure
data network technology. CDPD users connect directly to the Internet.
One analogy is that if the architecture of a CDMA or GSM network is like
dial-up access, then a CDPD connection is like having a dedicated
digital connection, such as an ISDN line.
In theory, CDPD networks offer better speed and quality of service
than connecting via a voice network. In practical terms, however, all
three approaches - and other variants including TDMA and PCS - are
generally limited to about 19.2 kilobits per second - about the same as
a slow modem connection. This type of connection is fast enough for
accessing email and light-duty Web surfing. The range is whatever the
cell phone network can support, and users can move around from one
location to another.
The advantage of using cellular networks for data interchange is that
they are available over wide geographic areas. This allows users to
remain connected while roaming over large areas. Limitations include
cost (connect charges can add up quickly) and limited bandwidth. You
also experience the usual problems with cellular networks, like blind
spots, interference from large structures, dropouts that occur as the
user moves from one cell to another and the lack of cell phone channels
when the system is under heavy use.
Applications of cellular wireless networks include email access,
instant messaging and transferring small text files. It is possible, but
not efficient, to surf the Web over a cellular network.
To make Internet access over cellular networks practical, Wireless
Access Protocol (WAP) and Wireless Markup Language (WML) have been
developed. These are protocols for transferring and rendering text on
the small displays commonly found on mobile phones and handheld
computers. They purposely exclude bandwidth-intensive multimedia
content. WAP and WML face competition from XHTML as well as I-Mode, a
proprietary standard developed by NTT DoCoMo, of Japan.
Ricochet
Ricochet is an alternative to digital cellular technologies like
CDPD, CDMA and GSM. It is a 128 kilobit-per-second wireless network that
has the same potential geographic coverage advantages of cellular
networks, but with bandwidth on par with ISDN lines.
Ricochet's major disadvantage is that the network is only deployed in
about 20 metropolitan areas nationwide. Ricochet is being deployed by
Metricom, San Jose, CA. End users purchase service and obtain wireless
modems from Ricochet service providers. The business relationship is
similar to that made with digital subscriber line customers, with
Metricom providing the network and individual service providers
supplying the connection to the Internet and account services. The
service offers ISDN speeds; unlimited service contracts cost about $75
per month. This makes it a potential competitor to wired DSL networks as
well as to other wireless services.
Applications for Wireless
No matter which technologies prevail, there's no question that rich
possibilities exist for mobile applications. In the pages that follow,
we share several examples of organizations that are empowering employees
and customers with mobile access to information. In most cases, these
applications rely on proven wireless LANs or untethered mobile computers
that are periodically synchronized with wired servers.
Until the future arrives and we can all enjoy broadband access to the
Internet, organizations can take the first steps with proven
technologies and simple-yet-practical computing tasks. As you'll
discover, companies can replace paper- and cost-intensive processes and
change the way they do business.
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