Many obstacles still hinder wireless communications, but expanded service offerings and new development tools are helping
Salvatore Salamone
Connecting to the office from remote locations is certainly easier than it used to be--many hotels catering to business travelers have added dataports to the phones in their guest rooms, and most airport terminals have public phones with modular jacks. But there are still numerous occasions when a wired modem connection is impractical or impossible: if you're visiting a client's office that has a digital PBX, for example, or if you spend much of your workday in a vehicle.
Mobile workers who have experienced the liberation of cellular phones are now demanding the same freedom for their digital communications. The most common need for a wireless link between a mobile worker and the office is to
exchange E-mail. But many companies would also like to use wireless networks to connect outbound employees with corporate data and applications stored on the network servers, minicomputers, and mainframes in the home office.
The expansion of wireless communications from E-mail and fax to remote data access will take some time. One study estimates that by the year 2000 about 25 percent of cellular data users will still be using wireless connectivity only for personal communications (E-mail and faxing). The rest of the market for cellular data services will be split among several distinct types of users (see the figure
"The Changing Mobile Market"
).
For example, service technicians need access to technical documentation or warranty information at customer sites. Delivery and inventory workers need to transmit information gathered about packages or products. And then there are the professionals who require a full mobile office that provides access to remote applications, d
ata, and personal communication services.
The companies that are trying to address this market face a number of obstacles (see
"Wireless Applications Stumbling Blocks"
). Perhaps the most serious problem is that low-bandwidth connections still plague wide-area wireless communications. In many areas, wireless networks are limited to data transfer rates of only 4.8 Kbps, which is much slower than the 14.4- or 28.8-Kbps connections now taken for granted with wired modems and analog phone lines. Wireless WANs look even worse when compared to wireless LANs, which typically deliver transfer rates of 1 to 2 Mbps.
Even if you're willing to settle for low throughput rates, there are still vast areas of the country (albeit mostly rural) that aren't covered by wireless services at all.
Another problem is the lack of standards. Businesses are often dismayed to discover they must use different wireless modems and develop multiple versions of the same remote-access software just t
o access all the different wireless services.
To compound this difficulty, some enterprises must develop their wireless applications to run on a wide variety of mobile platforms--everything from PDAs (personal digital assistants) with limited memory and processing power to Pentium-based laptops that rival high-end desktop systems. And as mentioned before, those mobile devices are increasingly expected to handle a lot more than just E-mail.
All these issues have kept most organizations from deploying wireless applications in any broad manner. Two notable exceptions are United Parcel Service and Federal Express, which use special wireless software and thousands of mobile computers to track all their packages in transit.
Fortunately, some recent developments should make it easier to create and deploy wireless applications. Wireless network providers are boosting their maximum throughput rates, new standards are coming with digital cellular networks, and there is a growing number of middlewar
e products that should ease the chore of developing wireless applications or adapting existing applications to wireless use.
Improved Services
Wireless services are available in virtually every major city in the U.S.--about 90 percent of major metropolitan locations have coverage, according to industry sources. And some kind of wireless service is available in about 30 to 40 percent of the rest of the country. All together, about 80 percent of the U.S. population can get access to wireless networking.
Currently there are four major wireless choices:
-- The existing cellular phone network is the most familiar method, because all you have to do is connect an analog modem to a cellular phone jack.
-- CDPD (cellular digital packet data) is offered by the large telecommunications service providers, including AT&T, Bell Atlantic Mobile Systems, Nynex, GTE, Southwestern Bell, McCaw Cellular, and Sprint.
-- RAM Mobile Data is a service of BellSouth Mobile Sy
stems and RAM Broadcasting.
-- Ardis is a joint venture of Motorola and IBM.
The two leading providers, Ardis and RAM Mobile Data, are constantly expanding their coverage into new sections of the country. That trend is likely to accelerate, thanks to increased competition from CDPD networks.
Less than a dozen cities had CDPD service by the end of 1994. But in January, the CDPD Forum announced that 20 additional cities--including New York, St. Louis, Dallas, and San Diego--would have commercial CDPD service by April. Carriers are expected to announce commercial CDPD services for the top 50 metropolitan areas during the first half of this year.
Despite this progress, CDPD still has quite a bit of catching up to do. Ardis--a two-way, store-and-forward, packet-based wireless network--is available in every state now and reaches more than 80 percent of the U.S. population.
However, don't get caught in a numbers game. Though the established service providers offer more extensive co
verage, they may not cover the geographical regions in which your organization's mobile workers need to roam. Wireless data services are springing up from the cores of metropolitan areas and expanding outward, much in the way cellular phone networks began to spread. This is a logical way for services to grow, but it may not fit the needs of organizations that wish to provide their mobile workers with access to corporate resources from far-flung locations.
For instance, it's not hard to imagine a field service technician at a customer site in a rural area who needs access to technical documentation stored on the LAN back at the office. This is an excellent application for wireless communications, but before a company can rely on it, wireless data services must be deployed across broad regions of the country.
Breaking the Speed Barrier
Another challenge for the wireless data industry is to overcome the traditionally low bandwidths of wide-area communications. Early users h
ad to accept 4.8-Kbps connections, which seemed frustratingly slow compared to wired modems. Ardis now offers speeds of 19.2 Kbps in most large cities, though smaller cities are still limited to 4.8 Kbps. CDPD services and RAM Mobile Data also operate at 19.2 Kbps.
Some service providers hope to carve out a niche market for higher-speed wireless services. For example, Metricom plans to introduce a 100-Kbps wireless service in five U.S. cities (Atlanta, Boston, Chicago, Seattle, and Washington, D.C.) by the end of this year. Metricom already offers a 77-Kbps service in parts of Silicon Valley.
Most users want the highest speed available when connecting from the field. When two wired modems or fax machines establish a link over an analog phone line, they automatically negotiate the fastest common speed they can support. After the link is negotiated, away you go. Ideally, wireless connections would work the same way. If Metricom's 77-Kbps service were available, your wireless device might choose th
at. If not, maybe it would route your connection through a CDPD link at 19.2 Kbps. And if you're in a small town and neither service is available, perhaps it would fall back on the 4.8-Kbps Ardis network.
Unless you've got a trunkload of wireless modems, however, your chances of accomplishing such a feat are small. Each type of wireless service requires a different type of modem. Even though all the major wireless networks--including Ardis, CDPD, and RAM Mobile Data--operate in adjacent parts of the 800-MHz to 900-MHz frequency bands, they each use different modulation and transmission methods. That means users must have a different proprietary modem to tap into each service.
And that was no joke about a trunkload of modems. Until recently, wireless modems were about the size of a brick. Carrying several of them wouldn't be practical for most people.
In March, the first PCMCIA wireless modems were introduced at the Mobile '95 show in San Jose, California. Both IBM and Motorola exhibited r
adio modems in the form of PCMCIA Type III cards. IBM also announced a modem that supports both CDPD and circuit-switched cellular service in a single device, providing mobile users with access to two wireless options. However, it's still a far cry from the level of standardization that lets you connect any wired modem to any modular phone jack and place a call over any local or long-distance telephone network.
There is, at least, some movement toward standardized command sets and common APIs for wireless modems. The PCCA (Portable Computer and Communications Association) has defined a set of extensions to the traditional TIA-602 AT (Hayes) modem commands. Any wireless modem, regardless of the service to which it's connected, can use these extensions.
In addition, the PCCA and the WINSock Forum are developing wireless extensions for the two most common network adapter drivers: NDIS (Network Driver Interface Specification) and ODI (Open Data-Link Interface). Their goal is to specify common APIs t
hat will make it easier to run LAN-based applications over wireless networks.
Wireless applications would be network-independent, so users could link their computers to any network. A single user could have access to several networks, or multiple users in different locations could have access to whatever services are available in their regions. In all cases, the same access methods would be used for any particular application.
Tightening Integration
Several vendors--including Motorola, CE Software, Oracle , Racotek, and Xcellnet--are concentrating on middleware that more tightly integrates existing applications with wireless networks. Their goal is to minimize the liability of restricted bandwidth.
For example, Oracle in Motion is a network-independent tool that lets a company develop Windows-based wireless applications. It uses agents to reduce the back-and-forth packet traffic that is common with LAN-based client/server software. In this case, Oracle in Motion u
ses an agent on the LAN to query a host.
Some of this middleware makes existing Windows applications compatible with wireless networks. For example, RadioMail Connection for Windows--developed by RadioMail and ConnectSoft--provides mobile messaging capabilities for Windows users. It's actually a wireless version of ConnectSoft's E-Mail Connection. With help from products like this, companies don't necessarily have to develop new wireless applications from scratch. Many existing applications can be used with little or no modification.
Thanks to new middleware, standardized command sets, common APIs, expanded geographical coverage, and improved transfer rates, the move to wireless WANs should be a much more manageable task.
WHERE TO FIND
Ardis
Lincolnshire, IL
(708) 913-1215
fax: (708) 913-4700
CE Software Inc.
West Des Moines, IA
(515) 221-1801
fax: (515) 221-1806
E-mail:
cesoftware@mcimail.com
ConnectSoft
Bellevue, WA
(800) 234-9497
(206) 827-6467
fax: (206) 822-9095
GTE Telecommunications
Atlanta, GA
(404) 391-8000
IBM
Armonk, NY
(800) 426-3333
(914) 765-1900
Metricom, Inc.
Los Gatos, CA
(800) 556-6123
(408) 399-8200
Motorola, Inc.
Wireless Data Group
Schaumburg, IL
(800) 233-0877
(708) 576-1600
fax: (708) 576-0710
Oracle
Redwood Shores, CA
(800) 633-0596
(415) 506-7000
fax: (415) 506-7200
Racotek, Inc.
Minneapolis, MN
(612) 832-9800
fax: (612) 832-9383
RadioMail Corp.
San Mateo, CA
(415) 286-7800
fax: (415) 286-7801
E-mail:
info@radiomail.net
RAM Mobile Data
Woodbridge, NJ
(908) 602-5500
Xcellnet
Atlanta, GA
(800) 322-3366
(404) 804-8100
fax: (404) 804-8102
-- Wireless networks must support increasingly complex applications
-- Low throughput rates
-- Support for a wide variety of mobile platforms
-- Service not ubiquitous
-- Lack of standardization
illustration_link (16 Kbytes)
By the year 2000, mobile workers will enjoy much more access to remote data and applications. That's in contrast to today's mobile market, in which wireless communications are primarily used for E-mail.
Source: McLaughlin & Associates (Chicago)
Salvatore Salamone is a BYTE news editor based in Manhattan. You can reach him on the Internet or BIX at
ssalamone@bix.com
.
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