Apple has just published a new and very useful Wi-Fi specification document which answers this question.
What is 4096-QAM?
It is the latest modulation technique that allows the access point and Wi-Fi client to send even more data over the air than ever before. Effectively, it adds 2 new MCS indexes 12 and 13 and unlocks faster data rates.
Achieving it is challenging as it requires very high Signal to Noise Radio (SNR) – that’s very strong signal and low noise. So in practical terms, it is only used quite rarely.
For context, with another client device using Intel BE200 Wi-Fi 7 adapter, I hit MCS 12 with SNR about 60-62 dB. In other words, if my noise floor was -95 dBm, my signal would have to be about -35 dBm.
Does iPhone 16 support it then?
According to the above spec sheet, the maximum Extremely High Throughput (EHT) the iPhone can achieve is MCS 11. 4096-QAM only uses MCS indexes 12 and 13. Check the mcsindex.net site.
So, the answer is no, it doesn’t.
Is it a dealbreaker?
From data rate perspective, even without 4096-QAM, and using 160 MHz wide channel, we are talking 2000+Mbps! Obviously depending on how far you are from the access point.
So I personally can’t complain. I value access to the clean 6 GHz spectrum, low latency and low retransmissions rate over maximum throughput.
My WAN link speed of 900 Mbps is my personal bottleneck and I usually don’t transfer huge amounts of data from the phone.
On a laptop, I can imagine 4096-QAM to deliver much more value when it comes to performing backups for moving very large software image or video files. Having said that, don’t forget that there is 2.5, 5 or 10 Gigabit Ethernet for that.