802.11ac (aka VHT, Very High Throughput) devices are required to support 20, 40,and 80 MHz channels and 1 spatial stream. Several optional features are also defined in 802.11ac:
Wider channel bandwidths (160 MHz)
Higher-order modulation support (optional 256QAM)
More spatial streams and antennas (up to 8)
400 ns short guard interval
Multi-User MIMO
STBC (Space Time Block Coding)
LDPC (Low Density Parity Check)
Table 1 Key features of 802.11ac
|
Feature |
Mandatory |
Optional |
|---|---|---|
|
Channel bandwidth |
20 MHz, 40 MHz, 80 MHz |
160 MHz, 80+80 MHz |
|
FFT size |
64, 128, 256 |
512 |
|
Data subcarriers / pilots |
52 / 4, 108 / 6, 234 / 8 |
468 / 16 |
|
Modulation types |
BPSK, QPSK, 16QAM, 64QAM |
256QAM |
|
MCS supported |
0 to 7 |
8 and 9 |
|
Spatial streams and MIMO |
1 |
2 to 8 Tx beamforming, STBC Multi-user MIMO (MU-MIMO) |
|
Operating mode / PPDU format |
Very high throughput/VHT |
|
A resonable case would be with 80 MHz bandwidth, 4 Tx beamforming and MCS9, and the data rates could be 1.56 Gbps; If the best case is configured with 160 MHz bandwidth, 8 Tx beamforming, MCS9 and short GI, the data rates could achieve 6.93 Gbps.