A Link Adaptation Mechanism For 802.11 Wireless LANs
Original Publication Date: 2002-Aug-18
Included in the Prior Art Database: 2003-Jun-20
Abstract: A link adaptation mechanism is described that can be implemented in a compatible way with the current 802.11 specification. Using the mechanism, an 802.11 compliant transmitter is able to detect whether the quality of a link to a certain destination is improving or declining, and based on this information to switch to a higher or lower rate, respectively. Introduction Two wireless broadband LAN standards are being developed in the 5 GHz band, namely IEEE 802.11a and ETSI HIPERLAN/2. The physical layers of both standards are very similar: they both use a modulation technique called "Orthogonal Frequency Division Multiplexing (OFDM)" and can provide several transmission modes with data rates ranging from 6 Mbps up to 54 Mbps. This multi-rate capability enables a WLAN station to select an appropriate transmission mode based on the current radio channel quality to reach the best performance.