Catch a Mobile Data Network to Go

Choosing between private and commercial mobile data networks.

by , / July 31, 1998
Many jurisdictions around the country are realizing the benefits of public-safety mobile data systems. "Mobile data" refers to a vehicle-based computing device that communicates wirelessly with a host computer system. Installing computers in police vehicles gives law enforcement personnel access to "silent" dispatch and status messages; local, state and national crime database information; vehicle-to-vehicle text messaging; and report writing and processing. Likewise, fire and EMS personnel can use mobile data for dispatch and status messaging and automated vehicle location as well as accessing pre-fire building plans, inspection history, HAZMAT information or other database information. In short, wireless mobile computing provides access to more complete and timely information, which enables police, fire and EMS staff to perform more effectively.

Since wireless networks are a critical component of mobile data systems, public agencies must decide how best to connect users in the field to host computers. Until recently, the decision was clear: Construct a private-data radio network -- vendor built, and government owned and operated -- to be used exclusively by a single agency or department. Today, commercial-data radio networks are becoming viable for law enforcement use. Government agencies now have the option of leasing a wireless network infrastructure and services, much as they would lease a wired network from the telephone company.

As with any technology investment decision, there are important factors to consider in assessing whether to build a private wireless data network or lease a commercial one: Cost, performance, security, flexibility and priority access must be considered.

What Is a Private Mobile Data Network?

Private wireless data backbones provide a dedicated network tailored to the specific needs of a public safety community. This approach requires your agency or jurisdiction to construct and operate its own wireless data network backbone, with responsibility for implementation, funding, operations and maintenance of the backbone infrastructure. You would also be responsible for licensing frequencies to be used for mobile data transmissions. Design and construction of a private-network infrastructure entails significant initial costs. However, these may be reduced through the strategic use of existing infrastructure, such as radio sites and towers.

Mobile data applications are typically implemented together with the private network as a single, integrated solution, although some systems integration is required for computer-aided dispatch and records-management systems (CAD/ RMS). Current private networks provide up to 19,200 bits per second (bps) data throughput per channel, sufficient for most text-based public-safety applications. They are designed to be secure and provide priority access to public-safety users. Private networks have a proven track record for public safety; most public safety mobile data systems operate on private wireless networks.

What Is a Commercial Mobile Data Network?

Commercial mobile data networks provide wireless data access to subscribers, including governmental and non-governmental organizations, using a variety of communication technologies, including specialized mobile radio (SMR), spread spectrum, cellular digital packet data (CDPD), satellite and others. Each relies on a terrestrial network for connectivity with host computers.

By using a commercial wireless provider, your agency avoids investing significant cost and time constructing a fixed, private infrastructure (for most private systems, the fixed infrastructure can account for 40 percent to 60 percent of the total one-time costs of a wireless data system). However, commercial wireless networks entail significant monthly subscriber fees per user. These recurring costs typically lead to higher system lifetime costs.

Many commercial wireless networks employ open protocols, support a variety of user devices and are easily scalable to allow for expansion. Nevertheless, significant systems integration is required to develop interfaces among applications and between the wired network infrastructure and the commercial wireless network.

One of the distinct advantages of commercial wireless networks is the increased bandwidth and data throughput they provide (up to 28,800 bps throughput per channel). Since commercial networks typically have more sites and channels than a private system, the design of commercial networks allows for more users to gain access at these higher speeds. In the future, commercial networks could more easily support data-intensive applications, such as mapping, digital mugshots and automated fingerprint identification.

Most commercial networks provide some security features, though many do not offer the ability to prioritize among all subscribers. As a result, during periods of high demand, public safety users could experience delays in transmissions as they compete with other users for air time. Presently, many commercial wireless networks in the United States have more than adequate capacity and, for many providers, the ability to easily add capacity.

Since most commercial wireless-network services have only recently become viable for mobile data applications, there are relatively few implementations, with data inquiry the most common application. Although a few small agencies have used commercial services for dispatch and status messaging, commercial networks are nonetheless considered to be untested for such mission-critical public safety applications.

Food for Thought

When comparing private to commercial approaches, keep the following issues in mind:

* Costs -- Public safety mobile data systems can be expensive, but they are one of the most important investments a government can make. They provide fire and police personnel with timely, direct access to information and enable law-enforcement officers to spend more time policing the streets.

The cost of any mobile data solution can vary greatly based on factors such as coverage, geography, topography, number of users, applications and the local market for wireless-data vendors.

Due to the differences between private- and commercial-network cost structures, governments must consider the full life-cycle costs when considering potential systems investments.

The continued proliferation of commercial network alternatives should drive down the price-to-performance ratios of all wireless network providers, both private and commercial.

* Performance -- Public safety users like the reliability and proven performance of private-network mobile data systems.

For private-data networks, additional users and applications can require the construction of new infrastructure or the addition of frequencies, which are expensive and difficult propositions.

In assessing network alternatives, agencies should consider long-term performance needs. Whether private or commercial, a network should support the addition of new users, as well as new applications, several years into the future.

Commercial wireless networks are pushing the limits of wireless network bandwidth and data throughput, providing an attractive alternative for data-intensive applications.

Many agencies are employing hybrid solutions that use commercial wireless networks for high-bandwidth applications and the tried-and-true private networks for mission-critical public safety messaging applications.

* Flexibility -- Due to their use of open protocols, the cost of switching between most commercial networks is relatively low. By contrast, the investment in a private-network infrastructure increases the cost of switching from one private-network vendor to another.

With the pace of change in technology today, governments desire technology investments with low-cost migration paths that allow them to easily take advantage of advancements in technology.

Governments typically rely on their chosen vendor to provide a migration path for proprietary private networks. In some cases, vendors have ceased to support a protocol, leaving agencies with an obsolete system.

* Application Integration -- Private-network vendors typically offer a fully integrated suite of mobile data systems; they have implemented such systems in hundreds of jurisdictions. This track record ensures public safety agencies of not only seamless integration, but proven reliability and technical support.

There have been relatively few implementations of fully integrated mobile data applications on a commercial network.

* Access -- With a limited, defined group of users, owners of a private network can predict how their system will react during peak usage (e.g., emergencies) and plan accordingly.

Commercial infrastructures have many different users besides public-safety agencies. Without priority access, corporate and individual users may "crowd out" public safety users, causing unacceptable delays for public safety users.

* Security -- Many public-safety agencies prefer to own their data networks for security reasons, feeling that it is too important to trust to anyone else.

While commercial networks offer many security features, skepticism among public safety agencies is likely to continue until commercial networks are fully proven in the field.

Not "Bleeding" Edge

Implementing a public-safety wireless data infrastructure is a complex proposition for any agency. Both private and commercial networks have benefits and drawbacks -- the relative weights of which will vary from agency to agency. While all of the above factors should be given due consideration, one of the most important considerations is risk.

Public-safety agencies are not inclined to utilize technology that has not repeatedly proven itself in the field. Many have taken a "wait-and-see" approach, delaying the purchase of new systems until commercial networks have been field-tested for all public safety applications. Gradually, more agencies have begun to test the waters of commercial wireless networks, but few are ready to take the full plunge.

Comparison Between
Private and Commercial
Wireless Data Networks Private
Networks Commercial
Major vendors National Some national,
most regional
Public-safety implementations Yes Yes
Public-safety dispatch
implementations Yes Few
System design To agency's
needs For broadest use
Control over prioritization Agency Vendor
System design Proprietary Proprietary &
Frequency ownership Agency Vendor
Coverage area Customized Varies
by vendor
Data rate Up to
19,200 bps Up to
28,800 bps
Measured reliability About 99 percent 95 percent
and greater
Time to implement Long Short
Over the air Provided
by vendor Provided
by vendor
Network Controlled
by agency Controlled by
vendor and agency

Andrew Anagnos and Martin Lind are consultants with The Warner Group, a Woodland Hills, Calif.-based management consulting firm specializing in the public sector. They can be reached at 818/710-8855.

The authors thank Greg Walker, a consultant with The Warner Group, for his contributions to this article.

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