For video surveillance applications, wireless technology offers a flexible, cost-efficient and quick way to deploy cameras, particularly over a large area as in a parking lot or a city center surveillance application. There would be no need to pull a cable through the ground. In older, protected buildings, wireless technology may be the only alternative if standard Ethernet cables may not be installed.
Axis offers cameras with built-in wireless support. Network cameras without built-in wireless technology can still be integrated into a wireless network if a wireless bridge is used.
802.11 WLAN standards
The most common wireless standard for wireless local area networks (WLAN) is the 802.11 standard by IEEE. While there are also other standards as well as proprietary technologies, the benefit of 802.11 wireless standards is that they all operate in a license-free spectrum, which means there is no license fee associated with setting up and operating the network. The most relevant extensions of the standards are 802.11b, 802.11g, 802.11a and 802.11n.
802.11b, which was approved in 1999, operates in the 2.4 GHz range and provides data rates up to 11 Mbit/s. Until 2004, most WLAN products sold were based on 802.11b.
802.11g, which was approved in 2003, is the most common 802.11 variant on the market. It operates in the 2.4 GHz range and provides data rates of up to 54 Mbit/s. WLAN products are usually 802.11b/g compliant.
802.11a, which was approved in 1999, operates in the 5 GHz frequency range and provides data rates of up to 54 Mbit/s. An issue with the 5 GHz frequency range is that it is not available for use in parts of Europe where it is allocated for military radar systems. In such areas, 5 GHz WLAN components should conform to 802.11a/h standard. Another disadvantage with 802.11a is that its signal range is shorter than 802.11g’s because it operates on a higher frequency; consequently, many more access points are required for transmission in the 5 GHz range than in the 2.4 GHz range.
IEEE 802.11n is the new generation standard (ratified October 2009) to improve network throughput over the previous standards with a significant increase in the maximum raw data rate from 54 Mbit/s to 600 Mbit/s with the use of four spatial streams at a channel width of 40 MHz.
When setting up a wireless network, the bandwidth capacity of the access point and the bandwidth requirements of the network devices should be considered. In general, the useful data throughput supported by a particular WLAN standard is about half the bit rate stipulated by a standard due to signaling and protocol overhead. With network cameras that support 802.11g, no more than four to five of such cameras should be connected to a wireless access point.
Due to the nature of wireless communications, anyone with a wireless device that is present within the area covered by a wireless network can share the network and intercept data being transferred over it unless the network is secured.
To prevent unauthorized access to the data transferred and to the network, some security technologies such as WEP and WPA/WPA2 have been developed to prevent unauthorized access and encrypt data sent over the network.
WEP (Wired Equivalent Privacy)
WEP prevents people without the correct key from accessing the network. There are, however, weaknesses in WEP.
They include keys that are relatively short and other flaws that allow keys to be reconstructed from a relatively small amount of intercepted traffic.
WEP today is no longer considered to provide adequate security as there are a variety of utilities freely available on the web that can be used to crack what is meant to be a secret WEP key.
WPA/WPA2 (WiFi Protected Access)
WPA significantly increases security by taking care of the shortcomings in the WEP standard. WPA adds a standard way for distributing encrypted keys.
Some security guidelines when using wireless cameras for surveillance:
- Enable the user/password login in the cameras.
- Enable the encryption (HTTPS) in the wireless router/cameras. This should be done before the keys or credentials are set for the WLAN to prevent unauthorized access to the network with stolen credentials.
- Ensure that wireless cameras support security protocols such as IEEE 802.1X and WPA/WPA2.
Some solutions may use other standards than the dominating IEEE 802.11, providing increased performance and much longer distances in combination with very high security. Two commonly used technologies are microwave and laser, which can be used to connect buildings or sites with a point-to-point high-speed data link.