An impressive attempt to summarise Wi-Fi which is a very deep topic. However I think the executive summary already missed the most critical thing about Wi-Fi:

only 1 transmitter at a time per channel - across all WLANs, yours and your neighbours, with no deterministic way to avoid collisions.

It's a shared medium and it's not even half duplex, unlike the dedicated full duplex you would typically get with an ethernet cable to a switch port.

The fact that Wi-Fi achieves what it does with this limitation, and how it co-ordinates the dance of multiple unknown clients using the same medium - and in the presence of other RF technologies to boot - is indeed an incredible technology story, but this achilles heel is the single most defining thing about Wi-Fi performance.

▲

Onavo 2 hours ago | parent [-]

Well the newer WiFi standards on 6Ghz support a lot more channels. Not a perfect work around by any means but it does significantly reduce congestion.

	▲	niobe an hour ago \| parent [-]
		Yes, that helps quiet a lot in practice because in most places there's limited "frequency-domain" capacity (i.e. free channels) but plenty of "time-domain" capacity, (i.e. free air-time). So even if you are sharing a channel with 4 other APs and their users, everybody may subjectively feel the network is fast. When chopping up the time domain into nanoseconds there's just a lot of idle time available, even if clients are pulling down files at 600Mbps. But at a fundamental level, the channel space (~60 across all bands best case) is extremely limited but the potential growth in transmitters is unbounded. It's like a linear hack to an exponential problem. It seems to work at first, but under very high load conditions performance still degrades ever faster until it falls off a cliff. Then there's all sorts of complex dynamic behaviour like the hidden node problem to add to this, but it all boils down to needing air-time and SNR.