Subject: [NEXTEL-1] Private Mobile Data: Mission Impossible?

From: [email-masked]
Date: Sat, 27 Sep 2003 22:01:38 -0400

Private Mobile Data: Mission Impossible?

By Todd Ellis
Consultant

From Private Wireless Magazine
September 2003

Of the many aspects our clients have asked about in regard to implementing
mobile data, surprisingly, many think about how the end product should work
without considering the logic of how to get from "Information Technology'
issues to the in-vehicle radio product. As a result, many
in the two-way radio field misread this as confusion and spend a lot of time
looking for that elusive "killer app." And, many wind up abandoning
the idea.

Mobile data can be segmented into three distinct groups of use: short
message data, minimized data, and, unlimited data. Short message data
is the most common use today. Products offered by many in the marketplace
fulfill this requirement. Status boxes, vehicle location products and
message displays from companies like CES Wireless are designed for such use.
These products interface easily into many products, and are marketed
horizontally to fit the needs of many different industries. They work well
over conventional and trunked radio systems, and in some
cases - like the MPT-1327 trunking format - they permit data transfer over
the control channel rather than use voice channels. The cost is relatively
low and interfacing is not difficult, but depth in features is lacking.

Minimized data is an important technique that is getting more attention from
system developers. Where software vendors strove for a "thin client"
environment that kept most of the data at the server side, minimized data
calls for a "thick client" - the applications are kept at the client side.
In
this way, smaller messages are sent to the client system in order to reduce
the amount of data transfer and minimize airtime. Once this concept
is embraced, exciting applications like graphical information systems (GIS)
and other complicated software products can be implemented in a
mobile wireless environment. This also leads to other software solutions
used to enhance workforce productivity.

The third technique is unlimited data access. This is simply web browsing on
a wide-open wireless connection. However, this method is not only
inefficient, it is also expensive to implement. If using public wireless
systems, the per-minute or per-packet cost can be very high. If using a
private wireless system, the cost of implementing a high-speed data system
to accommodate this kind of unnecessary throughput can be frightful. In
fact, many mobile productivity companies are offering products that are less
reliant on unlimited data, as unforeseen problems in the network can bring
operations to a thudding halt. At least with a thin client, the mobile user
can still use the on-board applications, such as mapping, report writing and
inventory control.

So - is there a "killer app" that fulfills a minimized data, thin client
environment, one that can work on a variety of mobile data radio systems?
The answer is yes. The application that everyone wants but doesn't know how
to label is called workforce management (WFM). This application is designed
to give mobile users access to back-office systems both to reference and to
interchange data between the mobile user and the office systems.

A Need for Back-Office Information

After interviewing more than 300 utility managers across the country, a
consensus was reached - field users need to see maps, to have access to
customer information and to dispatch work remotely. Additionally,
dispatchers need to utilize vehicle location to optimize assets for
dispatched work. WFM applications offer these kinds of features, and in some
cases, more. ViryaNet, based in Massachusetts, offers a well-designed
package that implements all of these features plus many more.

Once the application needs are defined, software specialists have to
integrate the existing back-office applications with the WFM application.
This task can sometimes be daunting, and in some situations, integration
costs can overshadow the benefits of having a WFM system. It also takes
time, anywhere from 30 days to two years depending on the complexity of the
applications. Yet many back-office software vendors are designing their
products for data portability so their customers can enjoy the advantage of
simpler integration with other programs.

Most of the software packages that utilize communications are designed for
TCP/IP, This protocol was designed with fullduplex wireline communications
in mind - not wireless or half-duplex channels. In many circles, software
designers think purely cellular communications and full-duplex techniques.
Although this works in metropolitan areas, it doesn't work in more rural or
suburban areas where a commitment to advanced technology and investment in
new infrastructure is lacking or non-existent. Furthermore, in the absence
of public data systems, private data systems require licensing and clear
channel use. And if these restrictions weren't swaying potential users to
depart at this point, operational data speeds on private data systems can be
so slow that practical use of the WFM system is negligible. Don't forget the
cost issues either!

A Mobile Data Makeover

Case in point - an electric utility wanted to implement a mobile data system
using an existing analog trunked radio system. This system offered a
non-TCP/IP data handling technique that allowed for long data messages
(packets of 512 bytes) to be sent over voice channels, while the
acknowledgement packets were sent across the control channel. The raw data
rate was 1,200 baud, but because of the trunking protocol and associated
overhead, the real net data rate was less than 150 baud. Aside from the
conversions to the software to accommodate non-TCP/IP "datagrams, the
software vendor was forced to find ways to minimize data content to the
extreme. At 150 baud, dispatches were taking minutes to transmit; and yet
the WFM system was reducing voice radio traffic by nearly 90 percent.

Time for a mobile data makeover! First, in this situation, the trunked radio
system fell by the wayside. A better solution would be to use something like
the Dataradio Gemini product line on a series of UHF channels. Through ITA,
protected UHF FB8 channels may be coordinated and utilized for this kind of
use. The Dataradio product is designed to operate in a multi-channel
pseudo-trunked configuration, where the radio scans a channel list for
available base stations without user intervention.

The Dataradio product has a unique method of what is called "IP spoofing."
The field user's Internet protocol address is used to communicate with the
Dataradio mobile product where the computer thinks it is communicating with
a full-duplex TCP/IP connection. However, it is cutting up the incoming data
into packets and sending the data over half-duplex channels. To add to its
versatility, the Dataradio product line utilizes a patented dual-receiving
decoding feature that reviews every incoming bit twice for accuracy. Using
this circuitry, this product boasts raw data speeds approaching 31 kilobits
per second (kbps) and practical rates of 26 kbps. This is a far cry from the
150 baud solution and leaps and bounds over non-TCP/IP compatible solutions.
Even better, software vendors can concentrate their efforts on other areas
aside from TCP/IP issues, and can optimize their systems to a more tolerable
data rate.

Another private wireless technique involves 802.11 unlicensed "hot spots" on
2.4 and 5.8 GHz. Hot spots are small footprints where mobile users can reach
access points. or small base stations that are connected to a centralized
network server. Hot spots can be located almost anywhere, and generally cost
significantly less to implement over other licensed technologies. However,
range is much smaller, and thus more hot spots need to be installed to cover
a geographical area. A side benefit of 802.11 implementation is that mobile
equipment costs are low. System providers like Cisco/Aironet offer complete
packages for access points, backbone circuits and mobile equipment.

Last, mobile users need computing equipment designed for their environment.
Panasonic manufactures a line of ruggedized computers for this kind of harsh
abuse. Consumer products simply Don't hold up, so avoid buying a cheap
alternative - experience demonstrates that it won't save a penny, and the
resulting downtime is unavoidable.

USAT of Chapel Hill, North Carolina, is a reseller for Panasonic computing
platforms and offers installation hardware for nearly any vehicle.
Concentrating on the utility market, these computers are being installed in
a wide variety of heavy equipment. USAT also provides a unique replacement
service whereby they can create a duplicate image of a customer's hard
drive, and place a spare on the shelf for their later use. In the event of
system failure or damage, downtime is minimized; the hard drives are modular
and easily replaced in the field, and can be sent by overnight courier
anywhere in the country.

Conclusion

So what is your preference: short message data, minimized data or unlimited
data? Or maybe the better question is, "how do I get there from here?" Each
one has its own complexities, upsides and downsides. But it is critical for
you to carefully choose the implementation route that is best for your
company's budget, timetable and work applications. With the guidance of a
qualified integrator, you can make mobile data work for you.

AUTHOR BIO

Todd Ellis has more than 15 years of experience in the computing and
communications industries. Throughout his career, he has worked with
companies providing various mobile data and computing system-level projects.
Ellis has conducted extensive business in the form of consulting,
contracting, system design, and project management both domestically and
internationally. He can be reached at 919.467.8160.

http://www.ita-relay.com/wireless.htm

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