It is 16usec. The 802.11a PLCP preamble is comprised both Short training symbol(STS) and Long training symbol(LTS). STS using for signal detection, freq. offset estimation, and AGC has 10 symbols of 0.8us each. LTS using for channel estimation has 2 symbols of 3.2us + 1.6us guard interval. -- Masafumi OE, NAOJ. -----Original Message----- From: ietf [mailto:ietf-bounces@xxxxxxxx] On Behalf Of sdrb Sent: Sunday, November 2, 2014 7:43 PM To: ietf@xxxxxxxx Subject: 802.11a preamble Hello, I'm reading 802.11a specs and trying to understand how long in microseconds is the 802.11a preamble. I know that 802.11a preamble is 12 symbols long plus one symbol for SIGNAL. But how can I convert it to time? I need to know how many data (counted in time) are added to 802.11 frame to be ready to transmit by hardware.