From: A Comparative Survey of Adaptive Codec Solutions for VoIP over Multirate WLANs: A Capacity versus Quality Performance Trade-Off
PLCP preamble & header
192.0 us
MAC Header + FCS
20.4 us
IP/UDP/RTP header
29.1 us
Voice Data
(Voice octets × 8/11)  us
ACK frame
10.2 us