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O N L I N E  E X C L U S I V E

Affordable Public-Safety Networks at 2.4 GHz

June 17, 2009

 

  

By Rory Conaway

 

Some mesh networks have recently been discredited when unrealistic business plans as part of municipal in partnerships with poorly written proposals failed. The failures were incorrectly attributed to unlicensed 2.4 GHz mesh technology instead of the financial models. The technology worked, but the real cost was never understood by the municipalities. Systems to support automatic meter reading (AMR), automated parking meters (APM), police cars, fire trucks, video analytics and surveillance and low-cost Internet for homes have been delayed because of a false negative impression.

The original designs attempted to provide everything to everybody. Cities wanted the mesh system to provide free or inexpensive Internet to the public, free access to government employees, mobile connectivity for public safety and video surveillance everywhere. In some cases, municipalities wanted vendors to not only pay for all of the equipment and installation, but to also pay rent to use the vertical assets. The models put forth by MetroFi and Earthlink were destined to fail. Free is not a business plan.

Because government agency budgets are crunched, many public-safety officials assume they can’t afford $50,000 to $150,000 per square mile for mesh systems. Fortunately for strapped government agencies, MuniWireless 2.0 has come to market. The release of new, and in many cases, less expensive equipment and more mature firmware is commercially available. New designs using next-generation equipment allow agencies to deploy municipal networks for less and add capacity and capabilities that weren’t considered in the past. These systems cost effectively deliver 100 Megabits per second (Mbps) or more of capacity, something only wired previously could do. When an outdoor access point (AP) for less than $100 can support up to 100 Mbps data speeds, moving vehicles and noninterference environments, the possibilities open up. The design can be deployed in rural areas or major cities.

New Designs

A new design relies on the concept that mesh isn’t the important technology in a municipal wireless system; pseudo mesh firmware can do most of what mesh firmware does for less cost. More equipment is available for the model at far less cost. The next step is a re-analysis of RF needs and what works. Eliminate the need for ubiquitous indoor coverage, and the number of required APs decreases. Combining low-power radios with higher-gain directional and omnidirectional antennas increases range and further reduces costs. Using 802.11n specification radios improves performance. If the goal is outdoor coverage for mobile vehicles, cameras or other needs, the density of the APs is greatly reduced. Coupled with the increased range from better antenna options, as few as four APs could cover 1 square mile and produce bandwidth of 10 Mbps or more. A deployment in Arizona is demonstrating this lower-cost design. A worse-case scenario in areas with high tree density or multifloor family homes made of brick or stucco is 16 APs.

The advantage of technology is that it never sits still. Manufacturers kept reducing the cost of equipment so each AP now costs $100 or less. If you add new technologies, an officer could use his laptop on a street corner with as fast a connection as at the precinct. That makes the starting cost of the deployment $2,400 – $9,000 per square mile for a system with enough bandwidth to support mobile radios and cameras at high resolution and high frame rates. Systems become affordable for both small- and large-sized cities. Throw in the cost of vehicle radios starting at $100 and some small laptops that start at $400, and officers have full network capabilities with speeds up to 40 Mbps or more. Such a system may not have all the bells and whistles of a multiradio mesh system, but at one-tenth the price of current municipal designs, you can’t beat the value and performance. A network can be expanded to support multiple backhauls and bandwidth of up to 80 Mbps of each AP for less than $100 each.

If the system is a multiuse design, the tradeoff is that security may not be as tight as some more expensive radios. Security still won’t be easy to compromise — more mature firmware is helping — but more care must be applied to design and egress access. For example, clients will need virtual private network (VPN) security software and a secure firewall/VPN solution. Laptops can use software solutions, and some car APs can run VPN tunneling software at the hardware level. Cameras can be secured with password protection. Departments can be separated by subnets; and at a minimum, the system should support Wi-Fi protected access (WPA) or advanced encryption standard (AES) level protection. Intrusion detection systems could protect systems. However, security needs to be examined in proportion to cost and application, so cost creep doesn’t compromise the financial goal of the original system.

New systems can also reject communications with any radios except for 802.11n units or those manufactured by a specific manufacturer, eliminating the majority of current Wi-Fi equipment. New 2.4 GHz radios support AES encryption and software and hardware VPN tunnels used by the U.S. Department of Defense. Concern about using 2.4 GHz due to interference can be addressed with more mature firmware, new radio designs and new specifications such as 802.11n. But in high-density areas, 2.4 GHz may have reduced range and multifrequency design using fail-over EV-DO, 4.9 GHz or 900 MHz may be required to guarantee connectivity. A small percentage of U.S. cities may require a more careful engineering study to deploy the technology correctly, but it’s still an option.

Public-safety officials often say they don’t have the money for municipal networks. But at current cost levels, departments can’t ignore the savings a municipal system can provide. For example, vandalism costs in a large city could run $500,000 or more every year. Throw in theft reduction because of cameras, reduced travel time of city employees, force multiplication of public-safety and AMR systems, and a municipal wireless system could pay for itself in months. If the APs are mounted on light poles, a $25 cable can also protect the copper wiring in the poles, which is expensive to replace and a favorite target for thieves.

Other than the obvious savings, the system could also generate revenue by selling subscription use, offsetting more of the costs or possibly turning a profit for a city. Because the cost of the network is low, a city could offer wireless from $5. With unemployment rising, many families are having difficulty affording Internet access at $20 – $60 per month. The system doesn’t have to be free, and users may be required to install radios on their houses to guarantee connectivity, limiting the complaint of lack of indoor coverage.

Multiple departments may have to work together to deploy such a system. The first part of the equation depends on who owns the light poles. If it’s the city, then utilities have to agree to the deployment. From there, information technology (IT) or the primary department should take on management and responsibility of security. If multiple departments are involved and cameras are deployed, agreements must be in place preventing users from saturating the network capacity or planning for expansion to support these needs. Expansion of the network is as simple as adding additional inexpensive radios to the system.

With additional modifications, a similar system could also upgrade supervisory control and data acquisition (SCADA), adding even more savings. SCADA radios range from $1,500 to $3,500. Radios for this system could run from $50 to $150, depending on the design. Either way, this system could provide as much as 1,300 times more capacity for functions such as video, alarms, or water quality or flow management in a system. Security for SCADA applications is even more important, but it’s still well within the capability of the system.

The age-old question of capability versus budget has now hit states and municipalities hard. With out-of-the box thinking, better network and RF design, and new technologies, municipalities can get technology that works for them and their residents. Police officers can be safer, agencies more efficient, residents more connected and everybody wins. It’s time for municipalities to re-evaluate municipal networks.


Rory Conaway is president and CEO of Triad Wireless, an engineering and design firm in Phoenix. Triad Wireless specializes in unique RF data and network designs for municipalities, public safety and educational campuses. E-mail comments to rconaway@triadwireless.net.

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