802.11h

---

This specification addresses the requirements of the European regulatory bodies in that it attempts to add better control over transmission power and radio channel selection to 802.11a. As such, 802.11h is actually "spectrum managed 802.11a."

In Europe (and elsewhere), there's worry about 802.11a transmissions interfering with satellite communications, which have "primary use" designation-most countries authorize WLANs for "secondary use" only.

European radio regulations for the 5 GHz band require products to have transmission power control (TPC) and dynamic frequency selection (DFS). TPC limits the transmitted power to the minimum levels needed to reach the farthest user. DFS selects the radio channel at the access point to minimize interference with other systems, particularly radar. Thus 802.11h is being written to avoid interference through the use of DCS and TPC, which makes it similar to HiperLAN/2, the dormant European-based competitor to 802.11a. To implement DCS and TPC, the 802.11h Task Group has developed associated practices that affect both the MAC and the PHY.

Ratification of 802.11h will provide better acceptability within Europe for IEEE-compliant 5 GHz WLAN products. (OEMs and systems firms including 802.11 interfaces in their products hopefully can expect pan-European approval of 802.11h sometime during the second half of 2003.)

Although European countries, such as the Netherlands and the U.K., currently allow the use of 802.11a under the condition that TPC and DFS must also be present, pan-European approval of the 802.11h standard (along with 802.11e) could be just the ticket to making 802.11a acceptable to many, if not all, local regulatory bodies.

---