"Technology has improved dramatically in recent years for data communications over the cellular network," said Rysavy. "In fact," he added, "the number of people sending and receiving data over the existing cellular network is greater than all of the other wireless networks combined. That makes it the leading wireless data solution out there today."
The newest kid on the block is cellular digital packet data (CDPD), a digital communications service that operates at rates of 19.2K per second. CDPD sends data packets over the existing cellular networks, taking advantage of idle time between voice calls to transmit data.
While it has barely arrived, CDPD is causing quite a stir for several reasons. First, it's twice as fast as packet radio and faster than switched-circuit cellular. It is also built on open standards, including the TCP/IP protocol. "That makes CDPD marketable for those folks who want to get onto the Internet from the field," said James Kobielus, senior telecommunications analyst at LCC Inc., a wireless network design and engineering firm. Kobielus also pointed out that CDPD automatically encrypts its data transmissions, ensuring the confidentiality of wireless data communications.
Because some of the leading communications firms, such as AT&T;/McCaw, Ameritech and Bell Atlantic, are implementing and marketing CDPD, the wireless service is expected to grow rapidly in the next few years.
"Based on marketing, availability, standards and data rates, CDPD stands a good chance of becoming the MS-DOS of wireless data communications," said Kobielus. "It may not be the fanciest or the most sophisticated wireless data protocol in the long run, but it will be everywhere, available to everybody and fairly cheap."
Two other kinds of wireless services could be of special interest to state and local governments for different reasons. Specialized mobile radio (SMR) is a highly secure transmission technology that's often used as a regional service. For those reasons, it has become popular with police departments.
Another emerging service is called spread spectrum, which is described as highly secure and is considered fast for wireless applications. Right now, only one company, Metricom Inc., offers spread spectrum service, and it's available in just a few major metropolitan areas.
What makes spread spectrum of interest to governments is its architecture, which relies on a mesh network of numerous, low-powered, micro-radios located on street lights, utility poles and buildings. Ira Brodsky, president of Datacomm Research Co., a consulting firm for wireless technologies, believes the technology could become a source of revenue as well as serve as a practical, high-speed wireless data communications system. "It would be easy for local governments to set up their own spread spectrum network on top of street lights, and then they could lease it, or they could franchise the poles' rights of way to a provider and use some of the capacity for their own use."
Whichever service a government chooses, they have to be prepared for working within an entirely different environment. "The radio environment is a hostile one," said Rysavy. "The kind of data rates it offers, the problems with drop-outs, interference and fading result in much less predictable data transmission than you would get over a wired connection." He added that wireless service providers compensate for these problems using innovative ways of protecting the data, but the end result is unpredictable delays in data transmission.
Such unpredictability presents special challenges for wireless customers. For example, existing software applications, such as electronic mail or database access cannot be ported directly to a wireless network. They will need to be configured to compensate for the changes in performance and higher costs.
"What you need to do is step back and ask yourself: What do we really need to be doing here?" said Rysavy. "What's the minimum amount of information we