802.11n Wi-Fi Successor: 802.11ac

Over the last couple of years, 802.11n was the Wi-Fi technology everybody was talking about. Now being including in almost any new device there's the inevitable question, what will be next? Sure, 802.11n designs can still be improved on, better antennas, better receivers and so on. But besides a successor is almost ready, 802.11ac. It looks they have run out of single letter characters for the designation but the main technical data is probably worth two characters:

• 80 MHz and 160 MHz channels (up from 20 MHz in 11g and 40 MHz in 11n when used), 5 GHz operation only.

• Two 80 MHz channels in different parts of the band can be bundled (to work around other users of the 5 GHz band, e.g. weather radar).

• 8×8 MIMO (up from 4×4 MIMO in 11n, up from 2×2 used in practice today in the mainstream)

• Multi User MIMO, so the 8×8 array can be used to send data to four 2×2 devices simultaneously, or three devices, one with 4×4 MIMO and two more with 2×2 MIMO. Other combinations are possible, too.

• Beamforming.

• 256QAM modulation (8 bits per transmission step, up from 64QAM in 11g and 11n).

• Theoretical top speed when everything is combined of 6.93 Gbit/s.

• Practical speeds perhaps 4-5 times faster than 802.11n today as most features are not mandatory but optional so they will only come over time if at all.

Here's a link with some more details by Electronics News and here, a first demo of 802.11ac single stream with an 80 MHz channel from the Wi-Fi in a Qualcomm smartphone chipset. 230 MBit/s. Not bad for a single stream transmission! And here's a link to another demo with an 802.11ac Access point by Buffalo, 80 MHz channel, 3×3 MIMO, 800 Mbit/s. Again, quite something and that's not even with a 160 MHz channel yet.