IEEE 802.11h

From ArticleWorld

The IEEE 802.11 is a set of IEEE standards that defines regulations for methods of wireless networking transmission. The versions of this set of standards commonly used are the 802.11a, 802.11b and 802.11g in order to provide wireless connectivity in the home, the office or the commercial environments where such a standard is used.

The International Telecommunication Union (ITU) recommended a set of rules so that wireless-LANs could share the 5GHz spectrum with important devices like military radar. Thus, the IEEE 802.11h was approved by the ITU. It refers to the IEEE standard for Spectrum and Transmit Power Management Extensions. It takes into consideration problems like interference with satellites and radar that happen to use the same frequency band of 5 GHz. The IEEE 802.11h standard provides Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC) to the IEEE 802.11a MAC.

In order to avoid radar and satellite interference, the DFS ensures that channels containing radar signals are avoided by an access point and that the energy is spread across the band so as to reduce interference to satellites. The TPC makes sure that satellite interference is brought down with the average power lowered below the regulatory maximum. Thus the power transmitted is limited to the minimum that is required to reach the farthest user.

This standard is meant as a supplementary to the MAC layer for 5GHz wireless LAN products. Originally meant to comply with European regulations, the standard is used in many other countries as well. With the development and implementation of these standards, access of the Internet over wireless devices such as cell phones, personal digital assistants ( PDAs) and laptops has becomes easier. Subsequently, the adoption of these standards has gained momentum.