Fredrik Nilsson is general manager of Axis Communications and an authority on IP surveillance.
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.
Point-to-point - When it is necessary to connect two buildings or sites with a high-speed network, a point-to-point data link capable of long distances and high speeds is required. These connections can be wired -- using fiber cabling -- or wireless, using radio waves or an optical link. Point-to-point can be a good option to consider when you're faced with the challenge of trying to create a central security command center when buildings are spread out among a large campus, or are separated in a town and it suburbs.
Some wireless point-to-point links require direct line-of-sight (LOS) between the two points in order to establish a connection. This means there must be a direct, visible path between the transmitting antenna and the receiving antenna to establish a link. This can prove difficult in mountainous terrain or in urban areas where taller buildings may disrupt LOS. There are cost-efficient solutions for point-to-point in the 900 MHz range that can transmit data a few miles with non-line-of-site (NLOS), and up to 40 miles with LOS.
Point-to-multipoint - Point-to-multipoint distributes data from a single source to multiple targets. The typical range is up to 15 miles at data speeds up to 72 Mbps. Point-to-multipoint links can be done with LOS or NLOS technology, depending on the needs of the surrounding area. Deploying a wireless point-to-multipoint system is much more cost efficient than a wired system that can require laying cabling across vast distances.
Mesh networks - In a mesh networking setup, all or most devices on the network are connected directly to each other. If one device can no longer operate, all the rest still communicate with each other; it's the concept of a "self-healing" network. Mesh networks work well when cameras are located at scattered points, but can be very expensive to establish when using wired connections. A wireless network allows these devices to network together without the need for physical cabling.
Security in Wireless Networks
Wireless networks allow for added flexibility in the placement of cameras and other networked devices throughout the system, but they require added security measures. WLANs are not necessarily bound by the walls of the buildings they serve, which open them up to security issues not faced with wired solutions. Due to the nature of wireless communications, everyone with a wireless device within the area covered by the network can potentially access its applications.
To address these concerns, there are a number of different methods for securing wireless networks, including Wireless Equivalent Privacy (WEP), WiFi Protected Access (WPA), and WiFi Protected Access 2 (WPA2), plus a number of proprietary solutions.
WEP - WEP encrypts data transmitted over the WLAN. Once WEP has been established, other typical LAN security mechanisms such as password protection, end-to-end encryption, virtual private networks, and authentication can be put in place to further ensure privacy. WEP adds encryption to the communication and prevents people without the correct key from accessing the network. However, the encryption code in WEP is static, which makes it vulnerable to attacks with inexpensive off-the-shelf software. Therefore it should not be the only method used to secure a wireless network.
WPA - WPA was created as a response to flaws in WEP. WPA works with most wireless network interface cards. With WPA, the access key is changed with every transmitted frame using Temporal Key Integrity Protocol (TKIP). This makes it much more secure, and it is now considered the basic level of security necessary for wireless networks.
WPA2 - For even higher security, WPA2 should be used. WPA2 uses Advanced Encryption Standard (AES) instead of TKIP. AES is the best encryption available for wireless networks today and is currently being used by the U.S. Government to secure sensitive, but not classified information. WPA2 is also referred to as 802.11i.
Some vendors have established proprietary modes of securing information on a wireless network. While these systems may be very secure, keep in mind that these can become cumbersome and difficult to manage when working with a variety of vendors on an installation.
Wireless networks can have a profound affect when used in areas it would be otherwise impossible to deploy a surveillance system. Ace Internet Solutions (AIS) installed a wireless IP Surveillance system when it moved to an industrial park in Chicago. There had been a rash of vandalism and theft in the area, and to help combat the problem, the company wanted to install a surveillance system to monitor an area which encompassed nine square blocks.
"Because all of the network cameras were set up outdoors, running data cabling to each of them would have been too costly and difficult to maintain," said Jeff Holewinski, president of AIS. "With a wireless connection, the cameras can transmit images no matter where they are, even from the top of light poles."
Using the wireless IP surveillance system, AIS deployed a wireless option and later discovered an extensive drag racing operation that was using the industrial park late at night for races. AIS worked with the Chicago Police Department, which was able to bust the ring, impound more than 100 cars, and make more than 300 arrests.
While wireless networks have many benefits, there are still a few drawbacks. Wireless networks can affect the frame rate and latency of video delivery, and bandwidth is affected by the distance from the device to the access point. Wireless networks are also susceptible to interference by other wireless technologies and systems.
However, wireless networks allow for cameras and other devices on the network to be moved quickly and easily without the need for expensive cabling. While there are still limitations and security concerns, they can still prove advantageous when used correctly for installations that would otherwise be too difficult or costly with wired networks. It is important to understand the benefits and challenges and analyze whether a wireless solution will meet your organization's demands before installing the network.
About the author: As the general manager for Axis Communications, Fredrik Nilsson oversees the company's operations in North America . In this role, he manages all aspects of the business, including sales, marketing, business expansion and finance. He can be reached via email at Fredrik.Nilsson@axis.com.