How to Buy Mobile Data Products

Have you ever played Technology Buzzword Bingo, or wanted to? It works like this: You get a bingo card with words instead of numbers in the boxes. The words include robust, mesh, cloud, scalable, 3.0, WiMAX, and WAN. Mark off a square every time you hear the salesman say one of the words. The first one to check off five in a row gets to throw the salesman out.

Tim Dees Headshot

Have you ever played Technology Buzzword Bingo, or wanted to? It works like this: You get a bingo card with words instead of numbers in the boxes. The words include robust, mesh, cloud, scalable, 3.0, WiMAX, and WAN. Mark off a square every time you hear the salesman say one of the words. The first one to check off five in a row gets to throw the salesman out.

This is the problem when cops go shopping for mobile data systems. Most cops don't have technical backgrounds, and they're easily snowed by the sales rep with the snazziest PowerPoint show. Coming up to full speed on the technobabble is probably more work than you want to do, but you can still be an informed customer and not totally at the mercy of the snake oil merchants.

Scoops and Flavors

Buying mobile data is a bit like ordering an ice cream cone-quantity and type are critical factors. The most common model allows officers in the field to make queries of wanted persons and property databases, motor vehicle bureau files, and maybe criminal histories from a laptop computer mounted in a patrol car. This reduces traffic on the voice channels and decreases the workload on the dispatcher. However, some agencies want to take this a step further and send call for service information directly to the officer's computer, and allow the officer to report status changes-call acknowledged, arrived on scene, assignment completed, and an emergency "panic button"-directly from the keyboard or a touchscreen.

Other applications include car-to-car text communications, access to unit status and calls pending screens, automatic vehicle location, e-mail, report writing and filing, two-way image and/or video transmission, and regular Internet access. All of these things are available with commercial-off-the-shelf (COTS) technology, but each requires bandwidth.

Bandwidth, in this context, is the size of the "data pipe" needed to support one of the aforementioned functions. Technologies that compress a lot of information into a small package have dramatically increased the amount of data a radio channel can handle, but there are limits to anything. Sending text, such as NCIC and motor vehicle inquiries and responses, requires the least bandwidth. Sound requires considerably more, and images and video even more, the last two heavily dependent on the resolution (fineness) used. This means that you're going to have to decide early on how you are going to get the data from your headquarters to the officer in the field.

Any existing computer-aided dispatch (CAD) or records management system (RMS) software will figure heavily into your mobile data decisions. The most efficient setup will dovetail with whatever you have. If not, consider what it will take to get your existing paper or electronic records into a new system, and how critical it is that mobile users have access to that information.

Cellular Network Providers

The radio spectrum is a crowded place, more so now than ever before. Consumer appetites for cell phones, wireless computer connections, high-definition television and radio, and all sorts of other gadgets have taxed the airwaves like never before. Fortunately, technology has kept pace with the demand by making it possible to fit more information into smaller data pipes. The bad news is that the channels are pretty much all spoken for, and you're going to have to use what's available. Sometimes, this means renting space from someone else.

Cellular telephone providers like Sprint, AT&T, and Verizon have claim to certain frequency bands, primarily for their cell phone subscribers. The all-digital technology of cellular phones allows for these channels to be used far more efficiently than was possible in the analog days. There is plenty of room for public safety data, almost as much as you could generate. Of course, you have to pay for it.

Chances are your agency is licensed to broadcast on certain radio channels dedicated for your use. Your outfit might not be the only one using those channels, but anyone else licensed for them is too far away to interfere with your communications. Because this is the model that most outfits have used for radio/wireless communications, it goes against the grain to pay for airtime on a recurring basis. This is mainly an issue of perception. We all pay for telephone service, power, heat, etc., on a recurring basis, and most of us pay a cell phone bill as well. Renting bandwidth for data communications is just an extension of that plan.

A significant advantage of running your data network over a commercial wireless carrier is that the carrier is responsible for the upkeep. A carrier with a lot of subscribers in a community has a strong incentive to build in redundancy and maintain the towers and other facilities they use. Depending on what kind of deal you work out with them, they may also have responsibility for the hardware at your headquarters and in your cars. There is considerable cost savings in not having to train technicians and keep them on staff, relying instead on your data carrier contractor. Of course, you are going to want them to guarantee performance and response times, because you will need them at the worst possible moments, when demands on both you and them are highest.

In any kind of disaster situation, the cellular networks will be saturated with traffic. Your emergency communications will have to stand in line with all the others if the carrier doesn't give you priority access to the channel. If power goes out, or a tower is brought down by wind or water, you'll need an alternate path to the network. Cellular providers have self-powered portable cell towers they can bring in for these situations. Find out how far away these portable towers are stored, and how long it will take to get one in service in a crisis. Don't forget that you will need some alternate method of communicating to the cellular provider that you need the emergency assistance.





Satellite Networks

Your service area may include regions where there is no cellular coverage. If the officers operating there need mobile data, one solution is to bring it from above. Satellite data communication is probably the most expensive alternative to conventional radio, but it's also one of the most bulletproof. Barring an electronics-frying nuclear explosion or a foreign power knocking a satellite out of the sky, your data network is reliable.

Most satellite network providers can give you voice and data in the same package. The hardware is fairly specialized, and chances are you will be single-sourcing your hardware and network with the provider. External antennas range from a roof-mounted dish about the size of a car door to a dome not much bigger than a pizza box. The topology, or shape/design of these networks, is often hybrid, with a land-based ("terrestrial") network mated with the satellite link. The satellite portion gets your data to and from the regional and national databases, and your local network distributes it from there. If your data pipeline to the national and global network is unreliable-for instance, if your headquarters is in a remote location-satellite might be your first choice for that portion of your network.


WiMax, or Worldwide Interoperability for Microwave Access, provides high-bandwidth data over a wireless connection. If you have seen "wireless broadband" advertised in your area, there is probably a WiMAX provider operating. Because WiMAX is deployed mainly in urban environments and can have spotty coverage, it's not often used for public safety communications. If you do have a WiMAX provider in your area, it's worthwhile to see if this data pipe can work for you, either as a primary source or as a backup data network.

Wide-Area and Mesh Networks

Cellular, satellite, and even a dedicated radio channel for data and/or voice can be combined with a wide-area network, or WAN. WAN is a large-scale version of the "Wi-Fi" wireless networks in airports, coffee shops, and many homes. Instead of a single low-power wireless access point at the computer, you place access points around town, on utility poles, and in cooperating businesses, so a mobile unit is within range of at least one access point some or all of the time. When it's not possible to get 100 percent coverage, officers go to areas where they know they can "hit" an available access point, and upload and download reports and make system inquiries.

After the 9/11 attacks, the FCC recognized public safety's need for bandwidth for mobile data, and allocated 50 MHz of spectrum in the 4.9 GHz band exclusively for fire, police, and EMS operations. These channels reside adjacent to the public Wi-Fi bands, so agencies use inexpensive COTS hardware for access.

Mesh networks are an expansion of this design. In a mesh network, every user terminal is also an access point. If Unit A is in range of an access point, and Unit B isn't, but is in range of Unit A, Unit A acts as a kind of relay for Unit B. The network is extendable as far as you can supply fixed point or mobile units as access points.

Mesh networks are also described as "self-healing," as the only single point of failure is the connection between the local network and the uplink, usually a hardwired, cellular or satellite line to the source national and global network. If any of the local access points goes out of commission, the others can fill in so long as at least one is connected to the source.

There are significant advantages to WAN and mesh networks. They allow you to start small, installing a few access points and expanding as your funds and ambition allow. Positioning access points in "dead zones" like large buildings and areas where radio signals are masked by terrain features gives coverage that a radio or cellular tower can't provide. It's easy to find sites for new access points, as businesses enjoy having officers parked nearby while they do their paperwork. Access points have minimal space and power requirements. And, of course, combining a WAN or mesh network with a data pipe from a hardline, cellular provider, and/or satellite to make a hybrid provides redundancy and eliminates a single point of failure.


Sometimes your data network provider gets to determine the hardware (computers, phones, PDAs, etc.) that will work with their network. When you do have some flexibility in purchase decisions, make sure the gear you choose is up to the job. Shock, vibration, and dust are hazards for any vehicle-mounted equipment. The climate in your operating area dictates the temperature extremes and moisture the electronics will have to tolerate. Spending money on a computer designed for a military MRAP vehicle is overkill, but expect to spend at least 50 percent to 100 percent more for a ruggedized machine comparable to a consumer-grade laptop.

Ergonomics are critical. If your officers have to twist and contort to use their computers in the car, you will pay out far more money on injured-on-duty back, neck, and repetitive stress injuries than you saved with a cheap mount. Do field tests with your largest and smallest cops to see what works. It's their office-and their lifeline.





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Tim Dees is a retired police officer and the former editor of two major law enforcement Websites. He can be reached at

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