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.
4096-QAM MCS indexes, credit to http://mcsindex.net
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.
High Tx (transmit) and Rx (receive) rates
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.
iPhone 16 supports tri-band Wi-Fi 7 and Multi-Link Operation (MLO). More specifically, the Enhanced Multilink Single‐Radio (EMLSR) mode. The client connects using 2 different Wi-Fi bands, only actively uses 1 of them and listens on both bands simultaneously. Let’s enable it on an access point and verify that it works.
Multi-Link Operation
We have a 320 MHz channel configured on the 6 GHz radio. This is for experimental purposes only. Please use narrower channel in production to avoid adjacent channel interference with other 6 GHz access points.
The tri-band SSID is announced in 2.4 GHz, 5 GHz and 6 GHz bands. It is up to the client device to choose the preferred band. MLO-capable Wi-Fi 7 clients can also enable the MLO feature.
Although iPhone 16 supports MLO, the phone itself doesn’t indicate if MLO is active or not. So our only option is to monitor it from the access point’s side. This is a consumer access point and it doesn’t provide a huge amount of detail. I am hoping to retest this with a proper enterprise-grade AP when I can.
Single band at a time
From the Association Request sent by the iPhone to the access point, we can see that it advertises support for only one band at a time.
With the default settings of the TP-Link Deco BE85 Wi-Fi 7 access point in place, the iPhone establishes MLO using 2.4 GHz and 6 GHz. It actively uses 6 GHz. 2.4 GHz is there for backup purposes.
TP-Link Deco app shows MLO using 2.4 GHz and 6 GHz
The iPhone uses its 160 MHz wide channel capability and actively pushes all data using the 6 GHz channel 69 as I am trying to demonstrate below using Oscium WiPry Clarity spectrum analyser. Check the “waterfall diagram” that shows the top 160 MHz of the 320 MHz channel being busy processing the data transmission.
MLO in action with iPhone primarily using 6 GHz band
The 2.4 GHz link just sits there in the background, unused. Using the same method, I verified that there is no spectrum utilisation whatsoever on the 2.4 GHz channel.
5 GHz and 2.4 GHz EMLSR MLO mode
When we change Preferred Wi-Fi Band setting to 5 GHz, the iPhone establishes 5 GHz active MLO link and 2.4 GHz as backup.
TP-Link Deco app
6 GHz and 5 GHz EMLSR MLO mode
Now, how do we force MLO using the two modern bands? For the purposes of the demo, I simply disable 2.4 GHz radio on the access point.
Disable 2.4 GHz using TP-Link Deco app
The phone establishes 6 GHz active data connection and uses the 5 GHz band as a backup. How can I be so sure? I watched the spectrum and generated nearly 900 Mbps of data over the wireless link. While the 6 GHz channel shows high utilisation, the 5 GHz channel shows no signs of use.
TP-Link Deco app shows 6 GHz and 5 GHz MLO
On the iPhone, we see active channels 69 in the 6 GHz band. That matches what I’ve just seen using the spectrum analyser.
Active 6 GHz channel 69 using max iPhone 16 channel width 160 MHz
How to trigger MLO band change?
Now, I connect the iPhone using 5 GHz channel. I am going to saturate the channel with other client’s traffic. My hope is that high channel utilisation makes the iPhone stop using the 5 GHz channel and switch to the backup 2.4 GHz channel.
And the result? It correctly detected and reported high channel utilisation, but the MLO band change did not happen.
High channel utilisation
So channel utilisation on its own did not do the trick for me. Perhaps the algorithm penalises and tries to avoid the 2.4 GHz band which is typically in a much worse condition than 5 GHz? Or high channel utilisation must persist for a longer period of time? Time will tell.
What chipset does it use? To find out we are going to enable Personal Hotspot on the iPhone and see what information we can get from the information elements it broadcasts in its beacons.
As we can see here, iPhone 16 uses Broadcom Wi-Fi 7 chip. That’s about the level of detail we can capture from the beacon frames it sends.
Broadcom chip
Continue reading
Does the iPhone 16 support Multi-Link Operation? Check this blog post.
All iPhone 16 models support tri-band Wi-Fi 7 as you might have seen here. But what is the maximum channel width they support in the 6 GHz band?
iPhone 16
Although my Wi-Fi 7 access point uses 320 MHz wide channel, the maximum 6 GHz channel width iPhone 16 supports is 160 MHz.
AP using 320 MHz wide channel
Here is the client view of the world.
iOS Wi-Fi Diagnostics profile provides extra information
Spectrum view
I am using Oscium WiPry Clarity 6 GHz spectrum analyser to see the spectrum. When we run a WAN speed tool Speedtest.net (it is not designed to be a Wi-Fi test tool) to generate some traffic here and see how it utilizes the 160 MHz channel.
Outside of that, I also checked the 2.4 GHz channel. There was no activity there. So that proves that only one of the 2 bands involved in MLO is active at a time.
Only the 6 GHz channel is active during data transfer, 2.4 GHz isn’t actively used
Updated: Apple’s iPhone 16 Wi-Fi specification
New documentation is now available directly from Apple. Note that 160 MHz is the maximum channel width for all models.
iPhone 16 Wi-Fi specification published by Apple
You normally won’t use 320 MHz wide channel anyway in Europe
Having said that, at least in Europe, we only have one 320 MHz wide channel available. So by the time you add a second access point you will have to downgrade to 160 MHz channels or narrower. That is to prevent the 2 APs from stepping on each other’s toes and causing adjacent channel interference. No support for 320 MHz channel width on the iPhone is not really a problem.
If you were considering using 320 MHz channels, or if your vendor uses that as a factory default setting, please be a good citizen and don’t.
All iPhone 16 models now support Wi-Fi 7 and come with 2×2 MIMO 2-Spatial Stream radio configuration. But Wi-Fi 7 doesn’t make support of 6 GHz band mandatory. So technically there could be Wi-Fi 7 clients that only support 2.4 GHz and 5 GHz.
Do iPhones 16 support all three 2.4 GHz, 5 GHz and 6 GHz Wi-Fi bands?
I tested a standard non-Pro iPhone 16 model.
It indeed supports all three Wi-Fi bands. Here is a proof of iPhone 16 connected to a Wi-Fi 7 access point using 6 GHz channel 69.
iPhone 16 connected using the 6 GHz Wi-Fi band
Using the My Wi-Fi Apple Shortcut we can look into another level of detail. In this case the iPhone is using the 802.11be Wi-Fi 7 standard to communicate with the access point.
iPhone 16 using Wi-Fi 7 802.11be standard
Association Request
As the iPhone associates to the AP, it announces no support for 320 MHz channel width.
