[Make-wifi-fast] [Cerowrt-devel] [tsvwg] Comments on draft-szigeti-tsvwg-ieee-802-11e

[Jonathan Morton]

Most of the overhead is waiting for the channel, negotiating for the
channel (RTS/CTS) which happens at the multicast rate, then syncing the
receiver (a constant time operation), signalling what rate *will* be used
for the data portion, and finally letting other stations know, at multicast
rate again, that the transmission is ending, and powering down the
transmitter. This is then immediately followed by the receiving station
transmitting an ack (hopefully).

During the above, both stations involve have to switch on, tune, use, then
switch off their transmitters twice.  This is a nontrivial task, for which
time is included in the protocol.  I believe the times have been shaved as
technology generally improves.

There is also some framing overhead which is transmitted at data rate, but
that vanishes next to the MAC overheads listed above.

- Jonathan Morton
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