Hacker News Reader

Nobody uses 512-QAM for WiFi, and for some good reasons:

1) it's not part of any current or draft standard;

2) it only encodes 9 bits vs. 8 bits for 256-QAM. Plugging this into GP's formula gives us:

1/3.6e-6 × 468 × 9 × 5/6 = 975 Mbit/s

3) current WiFi QAM constellations are all square [1,2], and there is no way to arrange 512 points into a square.

4) that would require an unrealistically clean channel, and give no advantage over lower-order modulations otherwise [3]