The IEEE 802.11ac physical layer is an extension of 802.11n, thereby maintaining backward compatibility with that existing standard. The theoretical maximum overall data rate for 802.11n is 600 Mb/s using 40-MHz bandwidth with four spatial streams. (Most consumer devices, however, are limited to two streams.) The theoretical 802.11ac maximum data rate is 6.93 Gb/s using 160-MHz bandwidth, eight spatial streams, modulation and coding scheme 9 (MCS9) with 256-state quadrature amplitude modulation (256QAM), and a short guard interval. A more practical maximum data rate for consumer devices might be 1.56 Gb/s, which would require an 80-MHz channel with four spatial streams, MCS9, and a normal guard interval.

2. This is a typical IEEE 802.11ac analysis display.

Both 160-MHz and 80+80-MHz modes are included as optional features in the IEEE 802.11ac standard. However, the first 802.11ac products are using 80 MHz bandwidth and up to 4 antennas. System simulation and test are supersets of existing scenarios. The main additions are the challenges of generating and analyzing higher bandwidths and the split bandwidth modes, and the complexity of the 8x8 MIMO functional test. Figure 2 shows a typical 802.11ac signal as displayed on a vector signal analyzer (VSA).