Lots of 2.4Ghz IoTs, will a 3x3 be better than 2x2?

[snovvman]

I currently have several AC86Us meshed in a large home. I have a lot of 2.4 Ghz IoTs--over a dozen cameras, thermostats, temperature sensors, sprinkler controller, plugs, etc. I am itching to upgrade to 6, 6E or 7 because my phones and computers can take advantage of it. I have 1G Internet service and 2.5G switch with a fully Cat 6 wired home.

Because of all the 2.4 Ghz devices, would keeping a 3x3 2.4Ghz device be helpful? I see many 6, 6E, even 7 APs that only have 2x2 for 2.4Ghz. Would this reduce the performance of my IoTs?

Thanks.

 

[Tech9]

because my phones and computers can take advantage

Computers may take some advantage, phones/tablets - unlikely.

Would this reduce the performance of my IoTs?

Also unlikely. All your IoTs are 1/2-stream low bandwidth devices.

 

[tgl]

Hmm ... probably not, really. "IoT"-class clients are almost certainly non-MIMO or 1x1, so as far as single-client performance goes it's not going to make any difference whether the AP can handle more streams.

In principle, a 2x2 AP can send to two different 1x1 clients concurrently, and a 3x3 AP to three such clients, so the 3x3 AP might be able to handle a lot of clients better than the 2x2. I'm skeptical that that's actually going to happen in your setup though, because according to some googling the AC standard defines MU-MIMO only in the 5GHz band. The AX standard brought it to the 2.4 band, but it's unlikely your existing APs will do that.

It's not clear to me whether an AX AP can do simultaneous transmissions to legacy clients, or whether the clients have to be AX-aware to make that work. If it does work then a 2x2 AX-spec AP could actually outperform your 3x3 AC-spec APs through being able to use concurrent transmissions.

And on the third hand, with these low-spec clients concurrent MIMO transmissions can only be done in the download direction in any case, so it's not going to matter unless you have multiple download-hungry clients. Upload-hungry clients such as security cameras will see no benefit.

 

[Tech9]

In principle, a 2x2 AP can send to two different 1x1 clients concurrently

It can't do that. There is no MU-MIMO on 2.4GHz 802.11n.

How many IoT devices support AX on 2.4GHz with Beamforming (required) and MU-MIMO?

 

[tgl]

It can't do that. There is no MU-MIMO on 2.4GHz 802.11n.

Yeah, that's what I said further down.

How many IoT devices support AX on 2.4GHz with Beamforming (required) and MU-MIMO?

Well, that's the question: do you need AX-aware clients to do MU-MIMO? The stuff I've found is pretty clear that a client needn't have more than one antenna to receive a stream in MU-MIMO, but not so clear on whether it needs other upgrades from 802.11n.

 

[Tech9]

Well, that's the question: do you need AX-aware clients to do MU-MIMO?

For MU-MIMO - 802.11ac Wave 2 or newer AP/clients. Plus client side support is required.

All Apple devices for example don't support MU-MIMO. It's useless in most cases anyway.

 

[snovvman]

Thanks for the discussion and information. I know the AC86U has 3x3 2.4Ghz. From a layperson's perspective, it is like having three lanes of road rather than 2x2 where it is two lanes. This might mean that if there are many 2.4Ghz devices, more of those devices can be serviced by the AP simultaneously (e.g., 3 at a time rather than 2 at a time) leading to less contention and latency. I know the concept of MIMO, but my simple assumption was that each single 2.4Ghz client can talk to one of the 3 2.4Ghz channels even if the client does not support MIMO. Is none of this true?

What is, then? If none of of the 2.4Ghz clients support MIMO, then is 3x3, even 2x2 even useful under AC? Are the clients simply all talking to the AP through a single channel?

My desire for upgrading from AC was that, aside from having something new to play with, that I can move my computers and phones to 6Ghz where it is less crowded.

Thanks again, @Tech9 and @tgl!

 

[tgl]

Per discussion so far, no, your setup probably cannot use MU-MIMO. So the AP's multiple antennas are only useful for boosting the data transfer rate to a single client that is also equipped with multiple antennas (this case is called SU-MIMO). There are 3x3 clients, but they're rare.

 

[snovvman]

Per discussion so far, no, your setup probably cannot use MU-MIMO. So the AP's multiple antennas are only useful for boosting the data transfer rate to a single client that is also equipped with multiple antennas (this case is called SU-MIMO). There are 3x3 clients, but they're rare.

I think I understand now. Unless both the AP and client support MU-MIMO, the communication between non-MU-MIMO clients and AP is through a single channel. The 2x2 and 3x3 are for clients that can communicate through the multiple channels. The 3x3 are not open lanes to multiple, simultaneous non-MIMO clients. Thank you.

 

[Tech9]

How it works with MIMO is the AP serves the clients one by one sharing time with the number of streams available and supported by the client. MU-MIMO in contrast can serve few clients at the same time sharing streams and it's obviously limited by the number of available AP streams. For MU-MIMO though Explicit Beamforming is a requirement. The AP and the client have to support Beamforming and MU-MIMO. This become a standard after 802.11ac Wave 2, but many clients don't support MU-MIMO because the real benefit of it is minimal even if all the requirements are met. It also doesn't work well with clients changing quickly the position relative to the AP.

 

[sfx2000]

In principle, a 2x2 AP can send to two different 1x1 clients concurrently, and a 3x3 AP to three such clients, so the 3x3 AP might be able to handle a lot of clients better than the 2x2. I'm skeptical that that's actually going to happen in your setup though, because according to some googling the AC standard defines MU-MIMO only in the 5GHz band. The AX standard brought it to the 2.4 band, but it's unlikely your existing APs will do that.

Erm - not really as traffic patterns won't trigger MU in any case with IOT devices...

 

[sfx2000]

Thanks for the discussion and information. I know the AC86U has 3x3 2.4Ghz. From a layperson's perspective, it is like having three lanes of road rather than 2x2 where it is two lanes. This might mean that if there are many 2.4Ghz devices, more of those devices can be serviced by the AP simultaneously (e.g., 3 at a time rather than 2 at a time) leading to less contention and latency. I know the concept of MIMO, but my simple assumption was that each single 2.4Ghz client can talk to one of the 3 2.4Ghz channels even if the client does not support MIMO. Is none of this true?

No - not how it works...

The client STA's see a single SSID and radio path...

Devices that support two radios, they will do MIMO, but this is a combined stream out of the baseband - a 3x radio isn't going to offer much here, but there is a diversity gain improvement, about 1.5 dB on both the uplink and downlink.

So a 3-stream radio will extend range a bit - what is more important is to reduce overhead and latency in 2.4 - best thing there at the moment is actually disable 11ax and 11b - 11ax has a fair amount of overhead, and with b/g/n/ax, this all happens at the lowest basic rate, which in 2.4 is 1 Mbps...

Yeah...

By disabling 11b, we bring the basic rate up to 6 Mbps, and we only use the OFDM rates, and this saves a shedload of airtime...

And as a pragmatic/practical view - there is little that 11ax currently offers to 2.4Ghz clients, as most of them do not suppot 11ax, and the few that do, the extra overhead in the shared medium isn't going to benefit any of the clients.

 

[snovvman]

- a 3x radio isn't going to offer much here, but there is a diversity gain improvement, about 1.5 dB on both the uplink and downlink.

So a 3-stream radio will extend range a bit - what is more important is to reduce overhead and latency in 2.4 - best thing there at the moment is actually disable 11ax and 11b

Thanks for the tips. I have disabled 11b. Since my AC86Us don't support AX, I won't have to worry about that for now.

I am curious about how a 3-stream can extend the range via diversity gain. Maybe that's why the AC86U still outperforms so many newer APs when it comes to range.

Thanks

 

[Tech9]

Maybe that's why the AC86U still outperforms so many newer APs when it comes to range.

If you are comparing to SMB APs - they are designed to work in groups and many have slightly directional radiation pattern. Home routers are designed to work as single AP with mostly omnidirectional radiation pattern. Different class devices with different target market.

 

[snovvman]

If you are comparing to SMB APs - they are designed to work in groups and many have slightly directional radiation pattern. Home routers are designed to work as single AP with mostly omnidirectional radiation pattern. Different class devices with different target market.

I'm comparing the likes of Asus AC86/88 type of APs with the Linksys Velop or TP-Link Decos. The Asus consistently has longer reach.

 

[Tech9]

Linksys Velop and TP-Link Deco are in "mesh" systems market where maximum range from a single unit is not the main objective. Now discontinued TP-Link Archer AC2300 was built around the same hardware as RT-AC86U and had similar range in AIO routers market. One of the best AC-class AIO routers for range was Netgear R7800.

 

[snovvman]

Linksys Velop and TP-Link Deco are in "mesh" systems market where maximum range from a single unit is not the main objective. Now discontinued TP-Link Archer AC2300 was built around the same hardware as RT-AC86U and had similar range in AIO routers market. One of the best AC-class AIO routers for range was Netgear R7800.

I see your point. Running the AC86U in a mesh gives better range all around, except I wish there was a Wi-Fi 7 successor to the AC86U/AX86U line. I want to be able to run 6Ghz on some of my devices.

 

[coxhaus]

I am no expert in radios but from my testing with an iPhone and a Cisco 4x4AC vs 2x2ax I was getting better coverage and a little longer distance out of my Cisco 4x4AC. It was not enough for me to stay with the 4x4AC as they cost a lot more. I can buy more 2x2ax APs for the same money and have better coverage using more devices. My IOT devices don't move so to me they either work or don't. If you are seeing lots of drops it could be you are overloading your AP which would mean that more APs would outperform 1 AP. An AP only supports a certain number of active talkers in which case you need more APs to carry the load. APs are not all designed the same and they have different power requirements. I would assume consumer APs are at the bottom.
The other thing that may make a difference is the power requirements. APs have 3 input power levels. There is POE, POE+, and POE++. My Cisco 4x4 required more power than my Cisco 2x2 so they may be able to create a better pattern with more power.
I did see issues with higher power levels and cables. I had to replace a CAT6 cable as it was making one of my APs run hot. My guess is the cable did not really meet spec. It was ordered off Amazon. I don't buy CAT cables off Amazon any more.

 

[Tech9]

I have 1G Internet service and 2.5G switch with a fully Cat 6 wired home

Since you already have investments in wired infrastructure I would suggest exploring SMB gear options and moving away from consumer products. You'll be happier in a long run with more configurable and expandable system with longer usable life. For lower cost and user friendliness replacing your routers with RT-AX86U Pro model will give you 3-4 years support extension with some extra configuration options around VLAN support in the new Asuswrt 5.0 firmware.

This new Asuswrt 5.0 firmware is too young though (initial release for RT-AX86U Pro at the moment) and don't expect everything working properly right from the start. It will take Asus perhaps 2 years to fix the issues and after 2 more years your hardware may land on End-Of-Life list. Some folks expect 7-10 years of support based on experience with AC-class products, but this is unlikely to happen in the transition period to Wi-Fi 7 plus the business model is different now.

 

[coxhaus]

Personally, I think it is too early for 2.5 gig connections. You don't gain that much over 1 gig connections with our current internet connections. Maybe in a small business. Some of the first Cisco small business switches supported 5 gig connections as I remember but they were not big sellers. The world was not ready 20 years ago. The world was too heavily vested in 10 gig.