Multi-bit Rate
802.11 allows for multiple bit rates.
802.11 allows for multiple bit rates.
Specific rates dependent on the version.
Algorithm for selecting the rate is not defined by the standard – left to vendors.
Packets have multi-rate format.
Different parts of the packet are sent at different rates.
Short vs Long preamble.
Preamble allows the received to synchronize with the transmitter.
Additional data is added to the header to help check for transmission errors.
Long.
Older, requires more data to help check for transmission errors (does it better).
Short.
Less data = faster.
802.11b: Long Preamble
Long Preamble = 144 bits.
Interoperable with older 802.11 devices.
Entire Preamble and 48 bit PLCP Header sent at 1 Mbps.
802.11b: Short Preamble
Short Preamble = 72 bits.
Preamble transmitted at 1 Mbps.
PLCP Header transmitted at 2 Mbps.
more efficient than long preamble.
Addressing Fields
Last updated
