Frame Tx Time Calculation for IEEE 802.11a/b/g/n/ac

1. IEEE 802.11b @ 20 MHz 
TXTIME = PreambleLength + PLCPHeaderTime + Ceiling(((LENGTH+PBCC) × 8) / DATARATE)

• PreambleLength = 144 us if using "Long Preamble"
                             = 72 us if using "Short Preamble"
• PLCPHeaderTime = 48 us if using "Long Preamble"
                                = 24 us if using "Short Preamble"
• LENGTH is number of bytes for Transmission Frame
• PBCC = 1 if using PBCC, otherwise is 0.
• DATARATE is data rate in bps for 802.11 (e.g., 1, 2, 5.5, 11 Mbps)

2. IEEE 802.11a @ 20 MHz 
TXTIME = T_PREAMBLE + T_SIGNAL + T_SYM × Ceiling ((16 + 8 × LENGTH + 6)/N_DBPS)
                = 16 us + 4 us + 4 us × Ceiling ((16 + 8 × LENGTH + 6)/N_DBPS)

3. IEEE 802.11g @ 20 MHz 
TXTIME = T_PREAMBLE + T_SIGNAL + T_SYM × Ceiling ((16 + 8 × LENGTH + 6)/NDBPS)
+ Signal Extension
                = 16 us + 4 us + 4 us × Ceiling ((16 + 8 × LENGTH + 6)/N_DBPS) + 6 us

4. IEEE 802.11n @ 20 MHz 
4.1 HT-mixed mode with short Guard Interval (GI)
TXTIME = T_{LEG_PREAMBLE} + T_{L_SIG} + T_{HT_PREAMBLE} + T_{HT_SIG} + T_SYM × Ceiling (T_SYMS × N_SYM / T_SYM) + SignalExtension

4.2 HT-mixed mode with normal GI
T_{LEG_PREAMBLE} + T_{L_SIG} + T_{HT_PREAMBLE} + T_{HT_SIG} + T_SYM × N_SYM + SignalExtension

4.3 HT-greenfield with short GI
TXTIME = T_{GF_HT_PREAMBLE} + T_{HT_SIG} + T_SYMS × N_SYM + SignalExtension

4.4 HT-greenfield with normal GI
TXTIME = T_{GF_HT_PREAMBLE} + T_{HT_SIG} + T_SYM × N_SYM + SignalExtension

5. IEEE 802.11ac @ 20 MHz