Today, 4.9 GHz public-safety wireless networks finally have moved away from theoretical deployments to the real thing, paving the way for endless applications, ranging from instant database access, field reporting and mapping to automated vehicle location, photo transmission and even streaming video.

It appears to be a win/win situation: Public-safety entities now can leverage commercial mesh Wi-Fi solutions while getting the high-speed data services they have been clamoring for in order to access more timely and accurate information. However, as obvious as these efficiencies and capabilities are, their actual performance hinges on how well the high-speed networks work. When inevitable coverage limitations or technological glitches become a factor, ensuring that basic communications between first responders continues uninterrupted takes priority.

When it comes to 4.9 GHz networks, coverage limitations are inevitable because of the nature of a mesh network. The propagation characteristics of the 4.9 GHz band mean a serial data network will require a significant amount of nodes, whether on the base-station side or on the client end. Therefore, blanketing a metropolitan area with a mesh network is cost-prohibitive for many municipalities.

Instead, they typically choose to provide services in the most active areas for the police and fire departments and use their 800 MHz voice solutions as a backup data alternative, which means the loss of data as first responders move out of the coverage area. Even if coverage is quite significant, first responders may roam across a plethora of 4.9 GHz networks in different municipalities.

These coverage issues have led to the emergence of applications that provide security and session persistence and allow users to seamlessly switch networks — resulting in a ubiquitous data network. This capability is quickly becoming a prerequisite for public-safety agencies building mesh networks.

“There simply is no one wireless technology that addresses all of the needs everywhere,” said Larry LeBlanc, chief technology officer with mobile gateway provider In Motion Technology. “The 4.9 GHz band is a fabulous answer for public-safety personnel, but the footprint isn't big enough. Fire trucks and ambulances are roaming across all coverage areas, and they need something to fall back on.”

In Motion recently teamed with mesh vendor SkyPilot Networks to approach municipalities with an end-to-end solution that builds 4.9 GHz mesh connectivity but also allows roaming onto commercial high-speed data networks such as CDMA 1xEV-DO or wideband-CDMA/HSDPA — networks that also are quickly proliferating.

In Motion already has a significant footprint in the emergency medical technician (EMT) segment. Its onBoard Mobile Gateway (oMG) 1000 allows EMTs to communicate with hospital personnel by providing a wireless local area network extension over commercial high-speed wireless data networks. And they can access information stored on the gateway's hard drive. As part of the complete mobile service delivery platform with SkyPilot, the oMG will transparently enable multiple Ethernet, Wi-Fi or serial devices in the vehicle to connect securely with the agency's headquarters over SkyPilot's 4.9 GHz technology or commercial data networks, based on available coverage.

“For the delivery of 4.9 GHz wireless access to be effective, the overall mobile data experience needs to be extremely robust,” said Brian Jenkins, vice president of product management for SkyPilot. “There's a lot of talk about the applications for 4.9 GHz, but the next step is having that same network allow for what looks like a glorified hotspot by allowing the ability to roam across a number of 4.9 GHz networks.”

Adding 4.9 GHz spectrum into its mesh product, SkyPilot recently launched the SkyExtender TriBand targeting the public-safety market. But it did so with a twist. SkyPilot's product launch included a new set of solution partners such as mobile virtual private network (VPN) provider Padcom, Ubiquity — which offers a 4.9 GHz laptop — and In Motion.

While municipalities are looking for mesh solutions rather than just mesh products, they don't necessarily have the resources to pull the various portions of the solution together. That need has given rise to 4.9 GHz ecosystem partners that support service launches in the band to help municipalities and their public-safety agencies get up and running. Ecosystem support is particularly important in the 4.9 GHz space, where off-the-shelf products aren't available as they are for standard Wi-Fi.

In the past, VPN solution providers such as Padcom and NetMotion Wireless have partnered with vendors on a project-by-project basis. For instance, Padcom partnered with Tropos Networks in Oklahoma City in January 2005 to deploy a solution that lets first responders access headquarters databases via the city's downtown Wi-Fi network. When first responders venture outside of the network's range, they are seamlessly switched to the M/A-COM EDACS network that blankets the city. Now, however, it appears that the public-safety community is leaning toward a one-stop solution.

Motorola has recognized the burgeoning desire for a full 4.9 GHz solution approach. In March, the vendor giant rolled out Multi-Net Mobility, a mobile VPN solution that complements its MotoMesh network solution, which is designed to deliver secure connectivity, session persistence and intelligent routing for wireless network users (MRT, April, page 66). The key to the platform is its unique ability to provide all three attributes, said Mike Fabbri, director of Motorola data solutions operation.

“We've partnered with companies like Padcom, but what drove us to develop our own [solution] is the fact that customers were saying there was no one provider able to meet all of three of these,” Fabbri said. “Some have one or two, such as security with session persistence.”

The Multi-Net Mobility system consists of a client application that resides in the customer's ruggedized laptop and a server application that sits in the core network. The client application constantly monitors the wireless applications available and facilitates intelligent routing as the user moves between networks. Meanwhile, the server application ensures the connection is secure.

Intelligent routing is particularly important when running applications such as full streaming video. Although users wouldn't want to run such an application on a low-bandwidth network, they also might want to avoid streaming video over a commercial carrier's network, to avoid incurring heavy access charges. In addition, most high-speed commercial carriers have strict regulations about what applications can travel over their networks for fear that bandwidth-intensive traffic might cause crippling congestion.

Although it seems clear that 4.9 GHz is not the panacea for wide-area broadband wireless coverage, it could come close once a host of municipalities roll out networks and enable roaming. There is a significant amount of work to be done logistically. Cooperation among various jurisdictions will be required to actually enable roaming and authentication. Plus, the desire for secure communications means that infrastructure must be built out, including authentication-management tokens as a way to assign use. That will require agreements to pass on common tokens to another jurisdiction's vehicles, for instance.

“There's a lot of work to be done, and we're actively pursuing the management of all this,” In Motion's LeBlanc said. “There's the back-office interconnect to get agencies to work with each other, and a lot of discussion is needed to get radios to interoperate in neighboring jurisdictions. Obviously, it's not a technical problem, because of IP, but we have an administration interoperability problem. Undoubtedly, there is going to be some hiccups.”