Improving Security with Wi-Fi Video Surveillance
October 11, 2005
Installing wireless video cameras is easy, and can improve the physical security of your facility. Learn what you need in order to deploy video surveillance solutions over wireless networks.
There are several companies, such as D-Link and Linksys, selling small video cameras that relay moving images to monitors and recording devices over Wi-Fi networks. The installation of these cameras is much easier than traditional units because theres no need to run wires between them and the companys network. The video signals flow over a wireless LAN and into a video server or PC. As a result, a company can set up a Wi-Fi video surveillance system much faster and in scenarios where its not feasible to install traditional wired cameras.
Wireless video surveillance is beneficial for many industries. For example, in California, San Mateo County installed Wi-Fi video cameras around the courthouse while the Scott Peterson trial was taking place. With this system, security officials could keep a continual eye on crowds and their behavior. In addition, public facilities such as hotels and shopping malls utilize Wi-Fi cameras to watch over shopping areas, elevators, and exit doors. Enterprises are also taking advantage of Wi-Fi cameras to monitor lobby entrances and parking lots.
- Identify electrical power sources. Video cameras are active devices and rely on electrical power to make them run. Many of the Wi-Fi cameras run on battery power, but keep in mind that youll need to replace the batteries periodically. So, determine whether this will work for your application or whether its more practical to utilize an AC power source. The use of AC, however, means that youll need to run wires to an electrical outlet, which will likely reduce the benefits of using a wireless camera.
- Be wary of water intrusion. Most Wi-Fi cameras are designed for indoor use. If youre mounting them outside, then place the cameras inside weatherproof enclosures or utilize cameras designed for outdoor use. Any water getting into the cameras electronics could disable the camera, and even water covering the cameras lens can significantly distort video images.
- Check for potential RF interference. As with any wireless LAN deployment, you should determine whether theres any potential RF interference that will degrade the operation of your wireless application. For example, a nearby microwave oven or cordless phone can dramatically slow down and even block the transmission of data over a wireless LAN, which negatively impacts the ability of the video signals to get between the camera and the network.
- Implement encryption and authentication. Weve all seen movies where thieves hack into the video surveillance system of a bank or hotel and fool the security people watching the camera monitors. The thief disables the video cameras and introduces a fake video stream that keeps security folks from seeing whats actually taking place next to doors, inside elevators, and inside rooms throughout the building. The thief can go about stealing things without anyone taking notice. Keep this from happening by choosing cameras that must authenticate properly with the network, and implement WPA or 802.11i encryption.
Potential Denial of Service
When deploying a Wi-Fi video surveillance system, you must be aware that its possible to deny the service of a WLAN. Someone, for example, could transmit a jamming signal that prevents the video cameras from transmitting. The 802.11 Medium Access Control (MAC), which Wi-Fi is based upon, is very polite. Radio cards in user devices take turns transmitting over a common RF channel. If another radio card is transmitting, or an interfering (or jamming) signal is present, then all radio cards will hold off from transmitting. This situation will disrupt the video camera signals. As a result, be very careful of not depending too heavily on Wi-Fi video cameras, especially if serious risks will result should the cameras stop working!
Jim Geier is the principal of Wireless-Nets, Ltd., a consulting firm focusing on the implementation of wireless mobile solutions and training. He is the author of the books Wireless LANs (Sams) and Wireless Networks - First Step (Cisco Press).