Despite the wide range of options for wirelessly connecting video surveillance cameras, video professionals agree on one thing. Where it is feasible to use a wired solution, integrators should choose that option, they say. As John Estrada, CEO of Cernium, explains, “If you already have wiring, you should use it; it’s more reliable.” Cernium is a Reston, Va.-based video camera manufacturer that does business as CheckVideo and offers both wired and wireless products.

There are times, however, when one or more cameras need to be installed in an area in which it would be difficult or impossible to run wire.

One commonly used option for wirelessly connecting video cameras is WiFi. Originally developed to enable laptop computers to connect to local area networks and the Internet, the technology also has found its way into some video surveillance cameras. Alternatively, cameras designed to communicate using IP can be plugged in to WiFi or other wireless equipment, although camera manufacturers may recommend the use of specific products from specific manufacturers for this purpose. At least one manufacturer — Cernium — also makes a gateway that wirelessly communicates images from up to four analog video cameras that are plugged into it.

One advantage of WiFi is that business customers often have already installed wireless LANs, minimizing the amount of investment the customer must make to support wireless camera connectivity. If dealers choose this option, however, they should consider establishing a virtual local area network (VLAN) for the video traffic, advises Edward Wassall, chief technology officer for Samsung Techwin America, a Ridgefield Park, N.J.-based WiFi equipment manufacturer.

“There are meters and tools that dealers can use to gauge how full the network is today,” Estrada describes. “You can do an analysis to determine if it will be able to handle the additional level of traffic.”

There are three different WiFi standards that are commonly used for video surveillance, all of which operate in unlicensed spectrum bands. Two of the standards — 802.11b and 802.11g — operate in the 2.4 GHz spectrum band. Equipment supporting the 802.11b standard supports a maximum data throughput rate of 11 Mbps, while 802.11g equipment transmits data at rates as high as 54 Mbps. The third standard — 802.11a — operates in the 5 GHz spectrum band and supports data rates up to 54 Mbps.

Where systems integrators have a choice of which type of WiFi to use — such as when they need to install a new WiFi network — they should seriously consider equipment operating at 5 GHz, advises Ebony Huang, CEO of Brickcom Corp., an Anaheim, Calif.-based manufacturer of WiFi and other wireless video cameras. The 2.4 GHz spectrum band is “nowadays widely used” notes Huang and may be “too noisy for video surveillance.”

It’s important to note that the 11 Mbps and 54 Mbps WiFi throughput numbers are maximum numbers. WiFi networks typically provide less bandwidth; the more interference encountered from other devices operating in the same band, the less throughput a network will support.

How many video cameras an individual WiFi access point can support depends on a variety of factors, explains Vince Ricco, North American business development manager for the technology partner program at Chelmsford, Mass.-based video camera manufacturer Axis Communications. These include the frame rate, the camera resolution and the type of compression used.

Ricco offers his advice on how to minimize bandwidth requirements without compromising quality. The human eye perceives motion at the equivalent of about 17 frames per second, Ricco explains. He notes, though that, “It’s hard to perceive the difference between seven frames per second and 17 frames per second from a loss-prevention standpoint.”  Depending on the distance between the subject and the camera, VGA resolution should provide sufficient clarity, Ricco asserts. If the background of the image is not constantly changing, Ricco recommends H.264 compression, which “only captures changes in the field of view.” Motion JPEG compression, on the other hand, refreshes each frame in its entirety, he says.

Wassall says he’s never seen more than four cameras work effectively on a single WiFi access point at 5 GHz. At 2.4 GHZ, he suggests dealers use no more than “one or two, tops.”

One way to minimize the amount of bandwidth required for video transmission is to store video on the camera itself and to stream images only when the system senses motion. That’s the approach that CheckVideo uses for its wireless video cameras, which use a combination of WiFi and cellular connectivity to stream a 10-second clip to a remote data center only when motion is sensed. With CheckVideo’s sytem, however, authorized end users are able to check in on cameras whenever they want to — and as Estrada notes, that option requires considerable throughput.

WiFi equipment, like other equipment operating in unlicensed frequency bands, may be subject to interference from other devices operating in the same band. Accordingly, its range is less than for some other wireless options. “Outdoors you can probably get 1,000 to 1,500 feet if there’s not a lot of blockage,” Estrada notes. “Indoors, if it’s placed properly you can probably get 30 to 50 feet down a hall.”

Alternatives to WiFi

Alternatives to WiFi for transmitting surveillance video include licensed and unlicensed options.

On the unlicensed side, San Diego-based MicroPower Technologies offers equipment that operates in that same 2.4 GHz band yet claims considerably more range — half a mile using line-of-sight transmission, according to CEO Jon Siann. As he explains, the company’s equipment is able to achieve that because it avoids data collision with other devices because it is “aware of what’s going on.” Each MicroPower hub can support four to six cameras and as many as three hubs can be installed in the same area, Siann states.

Another notable aspect of the MicroPower solution is that it does not require power to each camera, but instead is solar-powered. “The real innovation is that we have reduced power consumption to a level where solar power becomes practical,” Siann explains.

Boston-based Fluidmesh Networks offers wireless equipment at several licensed and unlicensed frequency bands that uses a proprietary transmission protocol and can be used with video cameras or access control readers (see related article, “Wireless Options in Access Control” on page xx). The equipment can be installed in point-to-point or point-to-multi-point configurations.

A third option is a mesh configuration, which according to Cosimo Malesci, Fluidmesh’s vice president of marketing, is the wireless equivalent of a fiber loop. Communications are transmitted from one camera to another to the head-end, adding redundancy to the system.

Licensed options are popular primarily with municipalities, which want the extra throughput they allow, Malesci says. The number of users at licensed frequencies is controlled through the licensing process, minimizing interference problems and enabling users to transmit at higher power levels. Malesci notes, though, that licensed options can cost 10 times as much as unlicensed options.

Another company that offers a licensed option for wirelessly transmitting video images or access control data is Orlando, Fla.-based Parseous Systems. The company uses spectrum in the 217-220 MHz band, which years ago was divided up into a large number of narrow channels intended for voice communications in industrial settings. Parseous has developed technology that aggregates up to 40 of these channels, which do not have to be contiguous, in order to support higher bandwidth communications over distances as great as nine miles, explains Parseous’ president and CEO, Brian Andrew. He cautions, however, that video cameras should not be set up for continuous streaming, but instead should transmit video only when motion is detected.

Customers must purchase licenses for every base station used, but each license costs just $100 for 10 years, Andrew says, adding that the signals are able to penetrate trees and other objects that might block other types of radios.

Some manufacturers also have begun to offer wireless equipment that works over cellular radio networks. The challenge with these systems is that traditional cellular rate plans are designed for consumer data and voice communications, which may not be appropriate for communications required for video and access control.

Ricco notes, however, that wireless network operators are beginning to recognize that they may need to develop special rate plans for the security industry. “They’re still grappling with it,” Ricco observes. “They’re talking to us.”