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.
Not true with newer standards:
> Orthogonal Frequency-Division Multiple Access (OFDMA) is a multi-user wireless transmission technology that divides a single Wi-Fi or cellular channel into smaller subcarriers called Resource Units (RUs), allowing multiple devices to transmit data simultaneously.
[…]
> Instead of one device occupying the entire channel (as in OFDM), OFDMA allows parallel transmissions. As a result, network congestion decreases significantly.
* https://www.netcomlearning.com/blog/what-is-ofdma
* https://airheads.hpe.com/blogs/antar1/2020/10/19/why-is-ofdm...
> In addition, the 802.11ax standard defines the smallest subchannel as a resource unit (RU), which includes at least 26 subcarriers and uniquely identifies a user. The resources of the entire channel are divided into small RUs with fixed sizes. In this mode, user data is carried on each RU. Therefore, on the total time-frequency resources, multiple users may simultaneously send data in each time segment, as shown in the following figure.
* https://info.support.huawei.com/info-finder/encyclopedia/en/...
* https://blogs.cisco.com/networking/wi-fi-6-ofdma-resource-un...
With a 26-Tone RU Type, nine devices can operate simultaneous in even a 20 MHz channel (eighteen in 40 MHz, etc); see Figures 2 and 3:
OFDMA on wifi7/802.11be: https://blogs.cisco.com/networking/wi-fi-7-mru-ofdma-turning...
As a general rule of thumb, the best version of WiFi x will only come with WiFi x+1. So for all the problems to be solved and ironed out on OFDMA it will be WiFi 8 then. And for all the promises of Ultra-High Reliability, it will have to be WIFI 9.
WiFi is clearly moving more towards like 4G and 5G with every version. I just hope someday that it really is good enough where there are many people using it at the same time.
That’s not correct. You and your neighbor can use the same channel at the same time. On your network, the transmissions of the other network appear will appear as noise. As long as the other devices are far enough away, however, your devices will still be able to make out their own signal.
When you and your neighbour _appear_ to be transmitting at the same time, each adapter is actually spending most of it's time waiting for a clear medium and for various backoff timers to expire before attempting to transmit.
"Appear as noise" is not defined for Wi-Fi adapters. There is only "I received a frame addressed to me and acknowledged it" or "I sent a frame and either did or didn't get an acknowledgement back from the receiver". Receivers do not know why they didn't receive a frame, or, if they received a corrupted frame, why it was corrupted. They just wait for a retransmit. Senders ordinarily wait a certain time to receive an acknowledgement, and if they don't, the start the transmit wait cycle again. But they often then reduce the data rate to increase the odds of a successful transmission.
I'm glossing over some complexity here, because there's a sender and receiver to consider, and each has a different view of the RF environment, but the point is always correct when all transmitters and receivers (lets say the 2 APs and each has 1 client) are in audible range of each other. And this is most of the time. Note that "audible range" (where the signal is such that the medium is deemed as busy by the adapter) is much larger than the "usable range" (where data can be transmitted at reasonable speeds). So transmitters create interference in a much larger area than they actually operate in.
That means your neighbour transmitting at 6Mbps to his AP will indeed degrade the performance of your client who wants to transmit at 600Mbps because your client has to wait ~100 times longer for a clear medium.
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.
This is surprising to me. I'd have guessed it decreases quadratically (i.e. due to the inverse square law), not exponentially.
The paragraph below seems to contain an explanation, but I don't really understand it (namely because I don't know what that percentage "Coverage" column actually means, or what we mean with "the total distance at each QAM step").
https://www.wiisfi.com/images/wifi-phy-table.jpg
Basically, it shows how a different encoding scheme/modulation is used based on distance (1024-QAM 5/6 - BPSK 1/2) (https://en.wikipedia.org/wiki/Signal_modulation), which is interesting!
If we think about it, any WiFi adapter (in its most basic core functionality) is just the ability to send/receive radio at a specific frequency, and a modulation (send) and corresponding demodulation (receive) scheme on top of that.
If the modulation/demodulation can be handled by a DSP, FPGA or fast-enough CPU, then all that's really required to create a WiFi device is that and the radio component, and then of course, there are devices like "Cantennas" that could give increased range, although loss of omnidirectionality is the trade-off there...
Anyway, I never thought about the fact that different encoding methods are used relative to distance prior to reading this article (i.e., I learned something!) -- but it makes perfect sense now that I think about it!
In case someone is interested, I got Claude to create a small Linux tool that analyze the capabilities of your WiFi adapter + the current established Wifi link, and explain each of them based on wiisfi.com: https://gist.github.com/severin-lemaignan/d3f854f6111e8275ae...
The 4x4 makes all the difference. Sitting in my car the 6+ would fight with my 4G for internet and cause maps to be super slow; now I'm off the property before its unusable.
I had intended to put APs in multiple rooms, but there doesn't seem like much point now.
Now every other brand is dead to me.
I've stuck with my Eero Pro 6 because it has 4x4 at 5GHz and the Pro 6E and 7 trade that for 2x2 at both 5GHz and 6GHz. The Max 7 has 4x4 on both 5Ghz and 6Ghz, but for a 3-pack for my house, the current pricing on amazon.ca is $2300, compared to the $650 I paid for the Pro 6 3-pack. (And the Pro 6 seems to have notably lower power draw than the Max 7.)
Otherwise you just have to run a wire through the wall and put an AP in the room. Your clients can still be wireless for the last few feet, which preserves the convenience of usage, just not the convenience of deployment.
Far (QPSK) 4(20Mhz)/5(80Mhz)/6(160Mhz)/7(320Mhz): 28.8/130/288.23/576.47
Near (64QAM) 4(20Mhz)/5(80Mhz)/6(160Mhz)/7(320Mhz): 144.4/650/1,441.17/2,882.35
Not bad for throughput increases, though most of the increases come from more spectrum, and the reliability comes from more MIMO antennas/streams. I've had WiFi 4/5 2x2 routers and something tells me I won't see much more than what's listed above for 7. Buying a 4x4 does get you a generation of throughput in advance pretty much, if you need it.
For contention between nearby Wi-Fi networks the BSS coloring feature is more directly relevant.
Finding it increasingly difficult to avoid bottlenecks though. Even with wifi 7 I still get 1.3 on my mac and 0.5 on iphone. More than enough realistically, but upstream internet is 1.7 so tiny bit unfortunately
Think I'm just going to wire the place with 10 gig fiber
>The speed advantages that Access Points have over mesh systems will become much more obvious with Wi-Fi 7.
From what I've read mesh devices generally can detect when they've got wired backhaul so they can stay in mesh mode for the clean handovers while not relying on it for actually moving data
Okay, we have wifi 6, now we're adding 6GHz. How do you know if you have 6GHz? You check if it says 6...e. And is wifi 7 an upgrade to that? Lol who knows, depends on the individual device specs. Check if it says tri-band, that will tell you it supports 6GHz... OR that it can support two simultaneous networks on one of the other frequencies.
802.11 is in general a vast swag of cool tricks, and when enough ideas are thrown at a wall, many do end up sticking, but for the most part the benefits are cumulative. MIMO being one major exception.
Another thing is that features like beamforming and higher QAM, let's say, are going to matter more in ideal scenarios where APs are in their sweet spot relative to clients, and you get to take advantage of high SNRs. Is that going to help when someone buys a Netgear Wifi 7 AP only to flip it upside down behind the couch in their apartment in an environment where 2.4 and even 5 ghz are basically gone from all their neighbors' use? Still, faster data rates mean clients get on and off the air quicker overall, saving airspace and battery if applicable. So, I think there's mainstream and highly specialized features rolling out simultaneously.
I think part of it is that if there isn't a regular and practiced process for bumping standards, then gaps between revisions can grow quite large and stagnation can set in, and if there are any significant improvements it'll take longer for them to come to fruition than if there were regular revisions that are only modest most of the time. Looking at a few other things that come to mind: USB had an 8 year gap between 2 and 3 as well, PCIe had a 7 year gap between 3 and 4 (albeit while they only had a 3 year gap between the specification for 5 to 6, it still took 3 more years (2025) for the first pcie6 devices, and I still can't buy a consumer-level pcie6 motherboard, it's a separate mess), C++ had an 8 year gap between C++03 and C++11, Java had a 5 year gap between 6 and 7 (and another 3 years after 7 to get to Java 8); all of these things now have more rapid cycles.
Just taking a swing at it, but I don't play that sport so probably a big whiff
The "old" cellular bands aren't generally open, at least in the States. We tend to use them for newer licensed stuff in cellular-land instead of the old licensed stuff we used to do. (Old modulation techniques die out and get replaced, but licensed RF bandwidth is still licensed RF bandwidth.)
Each data rate in the standard uses a different encoding technique. "Faster" encoding techniques cram more data into a given transmission interval but require a higher signal to noise ratio to be received without error. Since SNR declines with distance you can have a rough idea at what distance from a transmitter you will be able to receive at what data rate.
However, people and vendors focus far too much on maximum throughput. I've seen data showing that even in the best conditions, clients spend about 1% of their time transmitting or receiving at the highest data rates. Because they are dynamically adjusting the data rate based on the perceived SNR.
Individual clients' peak throughput also works against _aggregate_ throughput when talking about wireless networks with multiple users. If you have 100 clients, do you want one to be able to dominate the others or everyone get a more or less equal share? These peak speeds assume configurations that I would never deploy in practice, because they favour individual users and cripple aggregate throughput - things like 160 MHz wide channels.
But the sticker speed is what sells..
Correlated, but obviously bad code can really fuck with neighbors. And each client has an incentive to be greedy so users of that client get a better experience. So you fall back again to QOS for what you care about..
But you're technically correct!
But then again, the sentence uses the term "signal strength", not "throughput", so that would suggest quadratically. But I guess "signal strength" could be meant colloquially and mean more than just the raw signal power received by the antenna, here.
It's all very fuzzy to me, as it stands.
Where is it pretty common? I have never heard that (outside of being a mistake)
Because the variable is the base, not exponent.
I have a Netgear WAX218, one of the last cheap business-class APs I could find that don't require a cloud service to manage. WAY better than the pro-sumer wifi routers I was running before in access point mode. I'll have to look into Zyxel offerings a bit more when I'm ready to replace my Netgear.
> But as a very significant bonus, the 'extra' antennas if there is a mismatch in MIMO levels between the client and router do not go unused, but are used for 'diversity' and 'beamforming', which extends range, and improves speed at range.
You don't get higher max speed, but you do get better performance in general. I hadn't expected it to be drastic - I had thought it would be more theoretical than practical - so I had been planning on adding some 2x2 APs in a few months; but I don't think I need to now.
The original drive was because I have 4x4 on my desktop which won't get wired in for at least a year now; and my homelab is wired in.
And yeah, you pretty much already have to have a visible line of sight to get anything even close to 1 Gbps. And still be on channels with little interference. (DFS helps if you're not near radar, which intentionally causes you to get kicked off those channels and lose connection entirely.) And even then you might have to mess about a lot with positioning, because of reflections and generally multipath propagation.
I'd say it's not worth the headache. I would love to lay down Ethernet cable, even if it was just cabling only suitable for 1 Gbps (for which there's no good reason to, might as well do 10 Gbps).
But yeah, any mesh system worth its salt figures out the topology and absolutely favors wired links over WiFi for the back haul. Anything else wouldn't make any sense at all, there is basically no situation where you'd prefer an RF channel over a wire, unless the wire is maybe made of wet string.
If one considers that the higher speeds in 802.11ac and 802.11be require 256QAM modulation or better, this is completely expected (assuming 5 GHz band of course, which doesn't go through material very well at all). If you've sen a live eyeball chart of a 256QAM or 1024QAM constellation on test equipment for clear-air microwave link purposes, and seen how quickly it can degrade or get fuzzy if there's anything in the way of the link, it becomes more readily apparent. MCS levels 8 and onwards here:
https://en.wikipedia.org/wiki/Wi-Fi_7
"Clean" eyeball example of 256QAM: https://www.everythingrf.com/community/what-is-256-qam-modul...
examples of "fuzzy qam" in 16QAM, same principle applies to denser QAM
https://www.researchgate.net/figure/Typical-eye-diagram-Symb...
https://www.hp.com/us-en/shop/tech-takes/what-is-a-powerline...
If you have a set of full capability 802.11be clients you'll see the best performance with a 3x3 AP and 160 MHz channels.
It's unfortunately consumer grade tp-links so while they have actually been pretty good...you don't get a lot of knobs to tweak.
Still need to try MLO at some stage and they're currently acting as a bridge so (i.e. wifi backhaul) so think it might get better once I've laid fiber backhaul between them
On openwrt, DAWN or usteer can both help your APs to get sounding maps from clients and to tell them which AP to join. Looking at the sounding maps is very fun data to see: highly tecommend! The settings aren't the world's greatest but they are pretty good starts! https://github.com/berlin-open-wireless-lab/DAWN https://openwrt.org/docs/guide-user/network/wifi/dawn
Multiple APs are really nice because you can turn down the AP power, ideally, as you add more stations. Unfortunately I don't think you can tell a client to be quieter though; someone's laptop can be at 200mW tearing the hell out of the spectrum when everyone else is nicely conversing at 10-20mW.
Might try it again though, I'd love for it to work. And I was also dealing with some baseline wifi instability that I think firmware updates has resolved.
The point is that wireless networks can use not only the channel dimension, but the spatial dimension. That’s the basis of things like MIMO.
Per this May 2025 Juniper presentation, half of their deployed APs have 6 GHZ enabled, and at least 20%—but as much as 50% depending on the environment—of clients have 6 GHz:
* https://www.youtube.com/watch?v=sV-3gA0OP9s
Corporate environments (where client hardware is more standardize) has higher 6 GHz adoption, BYOD (universities) environments have lower adoption.
So I'm not sure how you define "a while" as, but it's probably already the majority at most workplaces, and will be for personal stuff with-in a year or so.
Yes, and? If a device only needs 26 tones, that's what will be assigned; if it needs 52 or 106, then that will assigned:
> RU allocations can happen with a combination of tones. For example – if there are three stations associated, then the AP can assign 106 tones to the first two users and 26 tones to the third user. The AP can also assign 52 tones to the third user. These RU allotment decisions are dynamically made by the AP based on the client’s traffic type and its available amount for transmission. The AP learns the client’s buffer status by using a periodic sounding mechanism.
* https://blogs.cisco.com/networking/wi-fi-6-ofdma-resource-un...
Scheduling is not static; Figure 4:
> In the first scheduling interval, the AP allocates the whole 20 MHz channel—a single, 242-tone RU—to Client 1. And in the third interval, it allocates two 106-tone RUs to Client 2 and Client 3.
* https://www.arista.com/assets/data/pdf/Whitepapers/WiFi-6.pd...
And can even be done on a per frame/PPDU basis:
* https://assets.ctfassets.net/wcxs9ap8i19s/2cAbZviv89ZKQZrXo9...
Why give one client more than it needs (when another client can also share the transmission time slot)? If it happens to need the entire x MHz channel, it may be given it (all the RU tones).
You’re overlooking the spatial dimension: https://en.wikipedia.org/wiki/Spatial_multiplexing
OFDMA was first used with Wifi 6:
* https://blogs.cisco.com/networking/wi-fi-6-ofdma-resource-un...
That's not correct. WiFi is "listen before talk." Radios listen to the channel, trying to decode preambles from other networks, before transmitting. In that process, they can detect other signals well below the threshold where they'll consider the medium in use (the CCA threshold). If you have an otherwise clean channel, the noise floor might be -95 dBm. Radios typically can decode the preambles 3-4 dB above the noise floor. Conventionally, the WiFi standards set the CCA threshold at -82 dBm. So the radio can "hear" a lot of signals that won't cause it to trigger collision avoidance. More recent standards allow using a CCA threshold as high as -62 dBM under certain circumstances to facilitate spatial reuse: https://arista.my.site.com/AristaCommunity/s/article/Spatial....
Also, what the Wifi standards do is less aggressive than what radios could do. The CCA thresholds are set to facilitate orderly use of the spectrum--they're not physical limits. To receive a transmission, you just need sufficient signal-to-noise ratio. An adjacent network transmission raises the noise floor, but if your radio is close enough to your AP, you might still have sufficient SNR.
If you have a good connection and are successfully able to transmit packets to your AP at 600Mbps, and your neighbour has a poor connection and is transmitting at 6Mbps to his AP at that moment, you literally have to wait ~100 times as long for a free medium before you can attempt to transmit. And that's for every single frame. Then you have to hope his client is well-behaved enough not to transmit while you are transmitting. Otherwise you end up having to wait again and retransmit anyway.
You might not notice this with only 2 clients. It might be the difference between a 80MBps and a 50MBps download for example. But it decays exponentially with the number of clients.
This is also why it's often better if everyone uses lower transmit power (while still retaining coverage), as networks farther away will see less interfering networks.
Agreed that signals like RSSI are device dependent. And open source software like DAWN is not the best at adjusting to this automatically. But in principle, most devices will give your AP a sounding map on request, and most clients will obey instruction to move to a different AP. Even really bad devices have generally worked ok for me at this.
The counter advice if use the minimum number of APs leaves pretty large zones of bad reception, and still already accepts the problem of roaming for many people. It's my hope that open source et al get better, get more competitive with what is clearly possible, especially given that we seem so well positioned to have control that could make good decisions here. To give up, when we have so much rich data & options, does not tempt me.
Even with many walls I was getting 300-400mbit/sec on WiFi vs 100mbit/sec on powerline.
'Plain' Wifi 6 (non-E) had zero 6 GHz. If you think otherwise can you produce a citation?
Edit:
I'd like to choose option C: I thought otherwise, and I was wrong in thinking that. I'd like to submit my previous comment, just above, as a citation demonstrating the incorrect thought process. ;)
Basically this. They way we usually put it is that we want clients to "get on and off the channel as quickly as possible". That requires all clients in range of each other to be behaving (respecting the rules) and using fast enough data rates to minimise their consumption of precious air-time.
Under the hood though, it's a very granular frame-by-frame, almost nanosecond-by-nanosecond thing that leads to the overall throughput at a human timescale. To give you a sense, let me try to summarise the factors affecting throughput this way:
- Data Rate: the transmitting client can adjust the data rate of each frame up or down per frame if they want. For example, a single TCP session on a 2.4GHz channel could in theory see data rates everywhere between 1Mbps and 450Mbps. But in practice most drivers I've seen adjust up or down incrementally. And in a healthy network, they usually hover around the top 25% of the mutually supported data rates (but they also spend very little time at the highest data rate, typically less than 1%). Also the AP could be using different data rate to the client, and usually is. The rx and tx directions are effectively separate streams and data rate is always chosen solely by the transmitter.
- Block Size: Similar to TCP windowing. Data can be sent in multi-frame 'bursts' before an acknowledgement is required by the transmitter for it send more. In the original Wi-Fi, every frame had to be acknowledged. Later standards introduced this idea of block acknowledgements.
- Re-transmits: Whenever acknowledgements are not received, the data has to be resent. Block size will be reduced, possibly to 1, so it will also take longer. Note that re-transmits are expected and very routine in Wi-Fi, whereas in TCP they are usually considered more of an exception (except on the internet). I've observed re-transmit rates of 20% in networks where no user is perceiving any sort of issue at all. So Wi-Fi is very robust to frame loss, up to a point, but even so, re-transmits do end up having a large impact on the aggregate throughput.
- Clear channel wait time: It's no exaggeration to say that transmitters spend most of their _waiting_ to transmit. And a big chunk of that wait time is just waiting for the medium to be clear - the clear channel assessment. If the client thinks there is a transmission going on, it just has to kill time.
- Other wait times: Even when the channel seems clear, there are various requirements to do nothing before and after transmitting. For example, the inter-frame spacing interval and the random back-off interval. These are just the rules of play. In fact, congestion avoidance on Wi-Fi could be said to be entirely a matter of timing.
Note that these are a simplification and clearly I can't mention everything or cover all the nuances. But, in the way I've framed it here, the clear-channel wait time and the re-transmit rate do basically encapsulate the impact of intangibles I didn't mention, like congestion and noise/interference.
TLDR; Wi-Fi transmissions are extremely lumpy at their native timescale, but many seem a lot smoother than many TCP transmissions at human timescales.
> Correlated, but obviously bad code can really fuck with neighbors.
Also true. Bad code is usually exemplified in Wi-Fi by bad drivers (looking at you Broadcom). These will cause clients to "stick" to bad APs when they should roam, or pick the wrong channel/AP/band in the first place. Intel is generally very good.
> And each client has an incentive to be greedy so users of that client get a better experience.
Greed is good in the sense that clients want to transmit their data as soon and as fast as possible and we want them too! But they have to respect the rules. Of course there's only a handful of chipset vendors so they mostly do. But within that, there's still plenty of room for clients and APs to do things that are _sub-optimal_ even if they are Wi-Fi legal, as per the sticky client example I mentioned.
> So you fall back again to QOS for what you care about..
Wi-Fi does indeed have its own implementation of QoS which is of course a timing dance! But I think you're referring to QoS in higher layers like IP. So it's worth mentioning that this WiFi stuff is all happening at layers 1 & 2. All the congestion detection and re-transmissions and so on that may be happening in higher-layer protocols like TCP are happening _in addition_ to what is going on at the WiFi layers.
The ones I have seem to be 2x2...with backhaul on wifi the 1.3 I'm seeing is probably just 1 then.
Aware of ubiquiti popularity in homelab circles. It's not for me tbh.
I've been through a couple of iterations of wifi gear - including a mainland china no-english Xiaomi...that was an adventure.
At this stage I don't think I'm tearing it out and buying new. "slow" gigabit internet on mobile device is an annoyance to my perfectionist side but I'll survive. And with a bit of luck adding fiber backhaul gets me above internet speed.
