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Wi-Fi basically replaces a cabled Ethernet connection with a wireless device. Current Wi-Fi systems operate in two unlicensed radio frequencies, 2.4 GHz and 5 GHz. The Institute for Electrical and Electronics Engineers (IEEE) has set four standards for Ethernet communications via these frequencies which are commonly referred to as 802.11a, 802.11b, 802.11g, and the latest, 802.11n. 802.11n has a throughput of 110 Mbps.

The user's distance from the Wi-Fi antenna, the uses of the same unlicensed frequencies by other devices, and the obstacles within and the structure of buildings which could interfere with the radio signals all affect the communications bandwidth received from the Wi-Fi antenna. Typical coverage areas indoors for omni-directional Wi-Fi antenna are 100 to 300 feet.

In the past, the typical use of Wi-Fi in buildings has coexisted with other wireless systems using the 2.4 GHz radio frequency such as Zigbee and Bluetooth. However, Wi-Fi has started to gradually move into the building control systems. Examples include Wi-Fi temperature sensors (tem- perature@lert product), Wi-Fi CO2 sensors (AirTest Technologies), Ethernet field panels with capability to use Wi-Fi transceivers to establish wireless connectivity (Siemens), and Real Time Location Systems (RTLS) (Cisco).

With more sensors, meters, and control devices generally needed in buildings, expect the adoption of wireless buildings systems to accelerate.

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