Sometimes wireless solutions are the best and most cost-effective option for IP surveillance installations. For example, wireless networks are a common choice in historic buildings where the installation of cables would damage the interior. Wireless is also a preferred option within facilities where there is a need to move cameras to new locations on a regular basis. The technology can also be used to bridge sites without expensive ground cabling, or to add cameras in difficult to reach locations such as parking lots or city centers.
Using wireless with network cameras and video servers can be done in a few different ways. Some cameras come with built in wireless functionality, but any network camera or video server can be incorporated into a wireless application using a wireless device point -- a device with an Ethernet port and a wireless connection or built-in antenna.
802.11 and WLANs
Wireless local area networks (WLANs) are the basis for most wireless networks. They allow mobile users and devices to connect to a Local Area Network (LAN) through a wireless connection which transmits data using high frequency radio waves. The process is similar to establishing a wireless Internet connection for home computers and laptops; likewise, a company can establish a WLAN allowing devices like computers and network cameras to connect to the network and transmit video.
WLAN standards are well defined, and devices from different vendors can work together, which allows for the vendor neutrality that end-users often request. The most commonly used standard is 802.11g, which provides higher transfer rates over greater distances than 802.11a and 802.11b. While the popular 802.11b has a maximum data rate of 11 Megabits per second (Mbps), the 802.11g provides five times that, with 54 Mbps. These are the maximum data rates, but typical data rates are about half that speed, and the further the device is from the access point the lower the bandwidth will be. 802.11b and 802.11g operate within the 2.4 GHz frequency. Keep in mind that higher frequencies shorten the distance that radio waves can reach.
While 802.11g is sufficient for full frame rate video, it operates at only 25 percent of a typical 100 Mbps wired connection. The next generation WLAN standard will be 802.11n and the "n" standard will greatly increase the speed of wireless data transmissions. This will improve the functionality of wireless IP surveillance systems as it will be possible to transmit video at even higher frame rates.
Alternatives to 802.11
Some solutions use standards other than 802.11, and many of these offerings can provide increased performance and much longer distances in combination with very high security. This includes the use of microwaves and satellites. A microwave link can provide up to 1,000 Mbps at up to 130 miles. Satellite communication allows for even further distances, but due to the way this system operates -- it transmits up to a satellite and then back down to earth -- the latency can be very long. This makes it less suitable for functions like controlling camera movement and video conferencing where low latency is preferred. If larger bandwidth is required, the use of satellite systems also becomes very costly.
WiMAX, or 802.16, is the standard for broadband wireless access. It enables devices with wireless connections to operate within a 30-mile range. It is being utilized for fixed broadband wireless metropolitan access networks (WMANs), including those in development in San Francisco and Milwaukee. WiMAX supports very high uploading and downloading bit rates to handle services such as Voice over IP (VoIP).
Types of Wireless Networks
There are three major types of wireless networks, each providing different benefits and functionalities. All three utilize wireless radio waves as the primary method for transmitting data, although there are a few other means of transmission.