IEEE 802.11b-1999

The project will evaluate the possibility orf taking advantage of the provisions for rate expansion that are in place on the current standard PHYs. The 802.11 MAC defines a mechanism for operation of stastions supporting different data rates in the same area. The current 802.11 standard already defines the basic rages of 1Mbit/s and 2 Mbit/s for both Frequency Hopping *FH) and Direct Sequence (DS) PHYs. The two rates are supported by having same header for both rates with length and rate information passed in the header at the lowest ("basic") rate; then the body of the packet is transmitted at the rate chosen and with the corresponding modulation method. The header structure of the two PHYs already supports passing rate information up to 4.5 Mbit/s (in 0.5 Mbit/s increments) for FH and up to 25.5 Mbit/s (in 0.1 Mbit/s increments) for DS. The proposed PAR targets further developing the provisions for enhanced data rate capability of 802.11 networks. The 802.11 MAC incorporates already the interpretation of this information and the computation of expected packet duration even if the specific station does not support the rate at which the packet was sent. The 802.11 MAC is compatible and will accommodate the higher PHY rates.