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Wireless Network Technology
Wired networks are present in most buildings. A non-wired solution has substantial value in some cases, both financially and in terms of functionally.
For example, in a building where the installation of cables would not be possible without damaging the interior, or within a facility such as retail outlet where there is a need to move the camera to new locations on a regular basis without having to pull new cables every time.
Another common use of wireless technology is to bridge two buildings or sites together without the need for expensive and complex ground works.
There are two major categories for wireless communications:
- Wireless LAN (also known as WLAN): A LAN is by definition a Local Area Network, i.e. over short distances and normally indoors. Nowadays, the wireless LAN standards are well defined and devices from different vendors work well together.
- Wireless bridges: When it is necessary to connect buildings or sites with high-speed links, a point-to-point data link capable of long distances and high speeds is required. Two commonly used technologies are microwave and laser
Wireless LAN standards
802.11a
The 802.11a standard uses the 5 GHz band and provides up to approximately 24 Mbps actual throughput at up to 30m/100feet in outdoor environments. A limited range of products support this standard. The theoretical bandwidth is 54 Mbps.
802.11b
802.11b is the most commonly used standard, providing up to approximately 5 Mbps actual throughput at up to 100 m/300 feet in outdoor environments. It uses the 2.4 GHz band. Almost all products on the market support this standard. Theoretical bandwidth is 11 Mbps.
802.11g
The 802.11g standard is relatively new standard and provides improved performance compared with 802.11b. Data rates of up to approximately 24 Mbps actual throughput at up to 100 m/300 feet are possible in outdoor environments. It also uses the 2.4 GHz band. Theoretical bandwidth is 54 Mbps.
About security in wireless networks
Due to the nature of wireless communications, everyone with a wireless device present within the area covered by the network will be able to participate in the network and use shared services, hence the need for security. The most commonly used standard today is WEP (Wireless Equivalent Privacy), which adds RSA RC4-based encryption to the communication, and prevents people without the correct key from gaining access the network. The key itself is not encrypted, and it is, therefore, possible to 'pick the lock'. WEP should be seen only as a basic level of security. A WEP key is normally 40, 64 or 128 bits in length. New standards being deployed significantly increase security, such as the WPA (WiFi Protected Access) standard, which takes care of some shortcomings in the WEP standard, including the addition of an encrypted key.
Wireless bridges
Some solutions may also use other standards than the dominating 802.11 standard, providing increased performance and much longer distances in combination with very high security. This also includes the use of other means of Radio Frequency, such as microwave links.
Another common technology is optical systems such as laser links. A microwave link can provide up to 1000 Mbps for distances up to 80 km/130 miles. For locations outside the range of all these systems, there is also the option of satellite communication. Due to the way this system operates, transmitting up to a satellite and back down to earth, the latency can be very long (up to several seconds). This makes it less suitable for functions like manual dome control and video conferencing where low latency is preferred. If larger bandwidth is required, the use of satellite systems also becomes very costly.
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