The spectrum differences
The 2.4 spectrum is the world's default frequency for WiFi communications. It's used by a variety of devices for a variety of purposes. When connecting to a "hotspot" at Starbucks, talking on a cordless phone, turning on the microwave oven or connecting to the office WiFi network, you're likely using 2.4. The advantage of 2.4 is that it's free, unlicensed and unmanaged spectrum... anyone can use it. The disadvantage is that it's free, unlicensed and unmanaged, and just about everyone uses it. Use a laptop to search for WiFi networks, and depending on location, you may "discover" 10 or 20 WiFi networks, all generating "noise" that clutters the spectrum.
As a result, 2.4 is a very crowded spectrum and, while it's fine for sending e-mail from Starbucks, it doesn't work well for mission- critical public safety applications. In a critical situation when an officer tries to connect to a 2.4 network, the result may be a complete failure due to range, coverage, interference and bandwidth limitations.
The 5.0 spectrum isn't much different. Like 2.4, it's free, unlicensed and unmanaged spectrum. While it's not presently as widely used as 2.4, it will soon face the same challenges.
Most 2.4 and 5.0 networks can provide up to 54 megabits-per-second (Mbps) maximum throughput.
The best choice for law enforcement
Fortunately, in America there is a better solution. The Federal Communications Commission (FCC) realized that 2.4 and 5.0 don't provide a viable option for public safety. In 2003, the FCC took action to solve this problem by dedicating 50 MHz of bandwidth in the 4.9 slice of the spectrum pie to public safety.
4.9 is licensed, controlled spectrum that is available exclusively for public safety use. As a result, it is clean, clutter-free spectrum that can support mission-critical public safety applications. In addition, 4.9, which also can provide up to 54 Mbps throughput, can be used at a higher power level, further improving its range and capabilities.
PacketHop, a provider of mobile-mesh broadband WiFi solutions supporting the 4.9 spectrum, has done range and performance tests that demonstrate the superior capabilities of 4.9.
In theory, 2.4 spectrum has a range in the thousands of feet between devices. However, in practice, the useful range of commercial 2.4 or 5.0 networks is much less - typically between only 50 and 500 feet - due to the interference resulting from the widespread use and limits on transmission power.
By comparison, PacketHop, located in Redwood City, California, has tested 4.9 networks with high-bandwidth applications to work beyond 3,400 feet - that's more than half a mile or 10 typical city blocks. For responding to a catastrophe, or just for everyday use, this 6x or better performance improvement could make the difference in successfully resolving an incident.
Municipal WiFi networks
Many cities are deploying or planning a WiFi network, often to provide the public with free or low-cost access to broadband Internet to bridge the digital divide. Improving the delivery of public services and public safety are frequently secondary motivations - when taken into account at all.
Most municipal WiFi networks are composed of a grid of access points (often mounted on light poles) to provide coverage. These access points are typically located within 500 to 1,000 feet of one another to create many interlinked WiFi hotspots. Most municipal WiFi networks use 2.4, and there may be dozens or even hundreds of people using a particular access point, creating a lot of WiFi traffic. This limits the bandwidth and connectivity available, making it unsuitable for law enforcement.
Some municipalities are planning ahead and incorporating 4.9 into their WiFi network plans so that public safety has the communications capabilities it needs. However, the onus may be on law enforcement to take the lead and address the issue with government officials - typically the IT director - to support 4.9.
How many agencies are using 4.9?
Interest in using 4.9 for public safety applications is growing. In the second half of 2006, more than 400 licenses were filed to use 4.9. However, based on a recent PacketHop survey of public safety/law enforcement done in conjunction with Officer.com, only a small percentage of the eligible public safety agencies have applied for a license. Of 418 people that participated in the survey:
- Only 7.7 percent currently have a 4.9 license;
- 6.7 percent plan to apply for a license within the next year; and
- 5.7 percent plan to apply for a license a year or more from now.