Local government agencies across the country are catching onto the benefits of wireless mesh networks. Some are looking to provide citizens with free or low-cost Internet access. Others have found that the networks can reduce labor costs by automating tasks such as reading utility meters. And many have found wireless networks to be ideal for sending data, such as mugshots and floor plans, to first responders equipped with computers in the field.
These networks are also proving to be very useful in transmitting and recording video for public safety and other purposes. Here are a couple examples:
• The town of Ripon, Calif., an upscale suburban community located near Stockton, has installed a wireless mesh network from Motorola that transmits video from more than 20 cameras installed in parks and in commercial and high-traffic areas. In addition to having recorded video for investigative purposes, the police department uses the network to access GIS maps, hazmat and homeland security information, and warrants.
• In Rockford, Ill., the housing authority teamed with the police department to install 16 wireless nodes from Firetide — each with its own camera, lighting and emergency intercom systems — to capture useful video for prosecution purposes and serve as a deterrent to crime.
Law enforcement, in particular, is turning to video transmitted via wireless mesh networks for traffic control, crime reduction, public safety at special events and for homeland security applications. Other departments such as transportation, utilities, and parks and recreation can also use the video.
Wireless Mesh: The Basics
A wireless mesh network consists of radio nodes working together to transmit video or other data. The data hops from node to node until it reaches its destination — most often a central monitoring station. One of the advantages of such a network is its redundancy — if one node fails, the others continue to communicate either directly or through intermediate nodes.
Mesh networks can work in areas where cabling would be prohibitively expensive or impossible to install, can be set up relatively quickly and be reconfigured or expanded to meet the changing needs of an end-user. The latter factor is a key element in any network design, as it also helps keep technologies current.
As a member of Security-Net’s TechNet group, I have had the opportunity to study and share wireless mesh network experiences with my colleagues across the country. Despite the technology’s many advantages for transmitting and recording video, we are all careful to complete a thorough site analysis to make sure a mesh network is really the right solution for each customer and its needs.
There are many potential problems that can affect a wireless mesh network. Trees, tall buildings and large bodies of water are a few of the topographical issues that might cause trouble in getting a video signal from the camera to the recorder.
“There are so many variables that you have to deal with when using mesh networks — it is not as controlled as setting down a length of fiber,” says Charlie Powell, of Indianapolis-based Koorsen Fire & Security. “The wireless mesh system that performs well transmitting over grass during the summer may have problems come winter, when highly reflective snow covers the ground.”
An experienced system integrator looking to design and install wireless mesh networks will invest in survey gear. I have a test kit that I use before installing, or even fully designing a mesh network. It consists of a couple of radio nodes, different types of antennas and tripods, a laptop computer and an IP camera or two. This gives a good indication if a mesh network is feasible for a particular site. But it is important to consider the environmental and other factors that may change over the coming months or years that could significantly impact a network’s performance.
Tom Horgan of InterTECH Security, based in Warrendale, Pa. says he has been working with a mesh networking solution from one manufacturer that preloads test modules into its offerings: “It includes a spectrum analyzer and is extremely easy to set up and test for electronic interference or other environmental issues you may run into,” he says. “The equipment is specifically designed to push video across the network.”
Professionally installed in the proper setting, a wireless mesh network should deliver video for recording at the same quality as that transmitted via fiber.
However, wireless mesh is not the right answer for all situations. Along with the environmental conditions, there are also bandwidth issues to consider when considering a mesh network.