Wi-Fi — the familiar name of the 802.11xx networking standards — is an essential cord-cutting invention. Just imagine how your smartphone or tablet would be without your home Wi-Fi.
So, in a nutshell, Wi-Fi is an alternative to network cables, allowing devices to connect to a network wirelessly. But the world of Wi-Fi can be confusing due to its many speed standards, frequency bands, features, and, well, other stuff.
This post will help you understand Wi-Fi at least as well as the next guy without getting embroiled in the networking jargon. This sure is a complicated topic, but pay a bit of attention, and you’ll have some fun along the way.
Dong’s note: I originally published this piece on May 6, 2018. It’s one of my first posts on DKT. I wrote it when Wi-Fi 6 had not even been available, and today there’s Wi-Fi 6E. This latest update, published on May 24, 2021, aims to paint an up-to-date picture of home Wi-Fi.
How does Wi-Fi work?
Wi-Fi uses radio frequencies to transmit data. It shares the same principle as any other technologies that use radio waves, including the radio itself.
AM and FM radio broadcasting stations use frequencies measured in Megahertz (MHz), Kilohertz (kHz), or even lower. Wi-Fi, on the other hand, uses much higher rates measured in Gigahertz (GHz).
Specifically, Wi-Fi uses the 2.4Ghz, 5GHz, 6GHz, and (rarely) 60GHz frequency bands. You’ll find more information on these below. To understand frequencies, though, we need to know what Hertz is, specifically what constitutes one Hertz.
What is Hertz?
Heinrich Hertz is a German physicist who conclusively proved the existence of electromagnetic waves in the late 19th century so that now we can take them for granted.
In the simplest terms, Hertz is the number of radio wave crests — or wave cycles — in 1 second.
Fill your bathtub with water. Wait till the surface is completely still. Now, throw in a little rubber duck. Note the waves travels outward. Pick one. Count the number of times the wave reaches its highest point in a second. If it’s once, then you get one Hertz; twice mean you have two Hertz, and so on.
OK, I know it’s hard to be precise on the counting, so don’t try too hard, but you get the idea. And it gets much harder. That’s because Wi-Fi uses frequencies in GHz. For example, 5GHz means there are 5,000,000,000 wave crests in a second. That’d take way too many seconds to tally up, so take my word for it!
In a nutshell, the higher the frequency, the closer the distance between two consecutive wave crests, which translates into a shorter length the wave itself can travel. However, that also means the more information you can put on it.
And this information travels between pieces of Wi-Fi hardware. Let’s find out what they are.
To use Wi-Fi, we need a signal broadcaster and a receiver. They are the two ends of a network connection. Specifically, the former emit Wi-Fi signals for the latter to catch on to form a wireless link.
For this to happen, the broadcaster can make the Wi-Fi an open network so any clients can connect to, or a secure network where only authorized clients can connect via a password. (More on this in the WPA section of each Wi-Fi standard below.)
Though mostly implied, this is called the “infrastructure” mode. In this mode, which is the primary way to use Wi-Fi, one broadcaster can host multiple receivers, but a receiver can connect to just one broadcaster at a time.
(Technically, you can configure two receivers to connect to each other in the “ad-hoc” mode. But this mode has little practical, real-world application.)
Typically, a Wi-Fi broadcaster is always called an access point (AP), a.k.a wireless access point (WAP). However, you more often run into Wi-Fi routers, which are standard routers with built-in AP(s). All home routers nowadays are presumed Wi-Fi routers.
The receiver is always a Wi-Fi adapter. In most cases, you don’t see an actual adapter since it resides inside the device (laptop or smartphone) you’re using. But if you have a computer that doesn’t have built-in Wi-Fi (or Wi-Fi of the standard you want), you can upgrade or change that out fairly easily.
A device, be it a computer or a handheld, with a built-in Wi-Fi adapter is called a Wi-Fi client or just a Wi-Fi device.
All Wi-Fi broadcasters and receivers have antennas. If you don’t see them, that’s because they are hidden on the inside or blended with other (metal) parts of the device.
Once we have a broadcaster and a receiver, the speed of a Wi-Fi connection between them depends on the Wi-Fi standard they use.
Home Wi-Fi explained and their standards
Wi-Fi standards are the way we manipulate the frequencies mentioned above. This is necessary partly because we can’t use just any frequencies. They are regulated — the hardware you buy is restricted to a certain spectrum.
And the regulation is a good thing because to communicate via radio successfully, devices have to agree on many standardized procedures.
(Sure, you can buy your own ham radio and make it use any frequencies, but in this day and age, that’s illegal. Also, your device might be useless since nobody uses the same frequencies to communicate with you.)
So, Wi-Fi standards are specific spectrums determined by the Institute of Electrical and Electronics Engineers (IEEE). Each time a spectrum is available for Wi-Fi use, we have a new standard.
Since 1999 there have been six major Wi-Fi standards: 802.11b, 802.11a, 802.11g, 802.11n, 802.11ac, and 802.11ax.
Newer standards are always faster than the older ones but are also backward compatible if they use the same frequency. Consequently, for the most part, you can use Wi-Fi devices of different generations together.
(Keep in mind that wireless devices connect using the standard they support, and you can’t tell which one they use unless you test the speed, use specific equipment, or view its status via an application. Wi-Fi signals are invisible. Literally, you can’t tell them apart by looking at the air.)
If you find the Wi-Fi standards’ name above weird and hard to pronounce, you’re not alone. The way they are, it’s hard to tell which is which, and they are all a mouthful to say to begin with.
This is where the new naming convention comes into play.
Wi-Fi naming convention
On October 3, 2018, the Wi-Fi Alliance introduced a new Wi-F naming convention using simple numbers.
Specifically, 802.11ax is called Wi-Fi 6 (because it’s the 6th generation of Wi-Fi), 802.11ac is now Wi-Fi 5, etc.
This new naming convention is a welcome change. You don’t need to wonder which is better between ac, n, or ax anymore. And it just makes sense that a higher number of Wi-Fi means a newer and faster standard.
Some Wi-Fi clients even show their connection with this new convention, Wi-Fi 6, Wi-Fi 6E, Wi-Fi 5, or Wi-Fi 4. Specifically, you right see a little number (be it 4, 5, 6, or 6E) next to the Wi-Fi symbol on your devices. Consequently, when there are multiple Wi-Fi networks of different Wi-Fi standards at a location, you can pick one that best matches your device.
(Keep in mind, doing that doesn’t mean you’d necessarily get faster Internet because Wi-Fi and the Internet are two different things.)
By the way, the first three standards (802.11b, 802.11a, and 802.11g) are now obsolete. And that’s great because you only need to care about Wi-Fi 4 (802.11n) and later.
Wi-Fi standards in brief
The table below includes all Wi-Fi standards and their brief attributes. Note that the Wi-Fi speeds mentioned here are all theoretical. The actual speeds vary greatly and are always much lower due to interference, distance, device compatibility, and overheads.
In my experience, in real-world usage, you’ll generally get about two-third of the theoretical speeds, at most.
|Common Name||Standard||Availability||Top Speed per Stream||Operating |
|Security Protocol||Frequency Bands||Status|
|N/A||802.11g||2003||54Mbps||20 MHz||Open |
or Wireless N
|60 GHz||Limited Use|
A Wi-Fi connection’s speed between two parties shares the same principle of a network connection — it’s always that of the slowest party. For example, if you use a Wi-Fi 6 client with a Wi-Fi 5 router, the connection speed will be that of the latter.
As you can see on the table above, each Wi-Fi standard uses its Wi-Fi band or bands differently. So to understand the significance of each standard, we need to know how each Wi-Fi band does its business.
Wi-Fi bands and their intricacies
Wi-Fi bands are the radio frequencies on which the Wi-Fi signals travel between an AP and a client. When it comes to Wi-Fi, we need to know the following bands: 2.4GHz, 5GHz, 6GHz, and 60GHz.
Common attributes of Wi-Fi bands
Each requires a specific hardware component. In other words, they don’t work interchangeably, and they are not available in all Wi-Fi standards.
But they have a few things in common:
Higher Hz numbers generally mean faster speeds and shorter ranges. It’s tough to determine the actual range of each frequency band because it fluctuates a great deal and depends heavily on the environment. Below are my estimates via personal experiences.
(Some might think these numbers are largely exaggerated, for others they are too conservative. Again, they are estimates.)
- 60GHz: This band’s range is extremely short that it has very few real-world applications — more in the section of the 802.11ad Wi-Fi standard below.
- 2.4GHz: This band has the best range, up to 175 ft (55m). However, this is the most popular band, which is also used by non-Wi-Fi devices like cordless phones or TV remotes. Its real-world speeds suffer severely from interference and other things. As a result, this band now works mostly as a backup, where the range is more important than speed.
- 5GHz: This band has much faster speeds than the 2.4GHz band but shorter ranges that max out at around 150 ft (46 m).
- 6GHz: This is the latest band, available with Wi-Fi 6E (more below). It has the same ceiling speed as the 5GHz band but with less interference and overheads. As a result, its actual real-world speed is faster. In return, it has just about 70% of the range, which maxes out at about 115 ft (35 m).
The actual Wi-Fi speeds are also determined by the number of partial streams and channel bandwidth being used. That said, let’s find out more about Wi-Fi channels and Wi-Fi streams.
Wi-Fi channels, in a nutshell, are a small section of each Wi-Fi band. They are like lanes on the road.
A Wi-Fi connection must use a particular channel at a given time. The channel width (or bandwidth) decides how fast a link is. It’s like a bike lane is slower than a car lane but faster than the sidewalk for pedestrians.
Channels are measured megahertz (MHz). There are four width levels, including 20MHz, 40MHz, 80MHz, 160MHz.
We need multiple contiguous channels to make up a wider channel. So a 40GHz channel includes two consecutive 20GHz channels, an 80MHz channel require two contiguous 40GHz channel (or four 20MHz ones), and so on.
As a result, a Wi-Fi band can deliver more lower channels or fewer higher channels. The 160MHz channel width is so wide that we can have only two out of the 5GHz band. Most importantly, both require the use of DFS channels.
Dynamic Frequency Selection (DFS) channels
Only available on the 5 GHz band, DFS channels are special ones that share the air space with radar signals.
Normally, these channels work just like any other channel. However, when radar signals are present, which often happens if you live within tens of miles from an airport or weather station, the router will move its signals to the next unoccupied DFS channel. During this process, your device might get disconnected briefly.
Not all clients support DFS, so most routers don’t use these channels by default for compatibility reasons.
160MHz vs. 160MHz (80+80) channels
A pure 160MHz channel includes continuous space, and as mentioned above, and needs to use DFS air space.
To avoid DFS, some Wi-FI chips have the 160MHz (80+80) mode, where it combines two non-contiguous 80MHz channels into a single one. This is somewhat of a hack and doesn’t deliver the same performance as a real 160MHz channel.
Over-lapping channels are those that multiple types of traffic can use — it’s like a bike can go on a lane designed for cars — and tend to be more susceptible to interference. On the other hand, non-over-lapping channels are like lanes explicitly intended for a type of traffic, such as a railroad or a car-pool lane.
Wi-Fi streams — often referred to as spatial or data streams — are how a Wi-Fi signal travels. A stream determines the base speed of a frequency band in a Wi-Fi standard. The more streams a band can handle, the faster its rate is.
You can think of the streams as the vehicle that uses the road. Depending on its size of the cargo space, it can move more or fewer goods per single trip.
Depending on the hardware specs, a Wi-Fi connection uses a single stream, dual-stream (2×2), three-stream (3×3), or four-stream (4×4). Right now, 4×4 is the highest, though there might be even more in the future.
Each Wi-Fi band and standard have a different base single-stream speed, as you can see in the table above. But in all cases, the concept of multiple streams remains the same.
Importantly note: In a particular Wi-Fi connection, the amount of streams being used is the lower number of the parties involved. For example, if you use a 4×4 router with a 2×2 client, you’ll have a 2×2 connection.
Bands vs. Channels vs. Streams
Bands, channels, and streams are items that make Wi-Fi confusing. So here’s my crude analogy:
A Wi-Fi band is like a road, where channels are lanes and streams are vehicles. On the same road, wider lanes are for larger vehicles. Vehicles with larger cargo spaces (2×2, 3×3, etc) can carry more goods (data) per trip (connection).
A Wi-Fi connection takes place on a single channel (lane) at a time, but the more channels there are, the more options hardware devices have to deliver better speeds.
The evolution of Wi-Fi
Now that you know Wi-Fi works let’s find out how it progresses via different standards. Other than faster speeds, each new revision of Wi-Fi gets more features and better security.
Again, since the older standards are now obsolete, we’ll start with Wi-Fi 4.
Wi-Fi 4 (802.11n)
Wi-Fi 4, also known as Wireless-N, uses 20MHz and 40MHz channel widths and up to three streams (3×3). A single stream delivers 150Mbps (40MHz).
Wi-Fi 4 is when we also have:
- The designations of combined speeds
- The popular use of WPS and Wi-Fi Protected Access (WPA) security method.
This is when a Wi-Fi device operates in 2.4GHz and/or 5GHz at a time.
Dual-band is a compatibility necessity. Some Wi-Fi devices only use the 2.4GHz band, and others use the 5GHz. So for devices to work interchangeably, regardless of their standard, dual-band support is a necessity.
A dual-band broadcaster has two access points, one for each band. A dual-band client similarly has two wireless receivers.
Keep in mind that “dual” doesn’t mean you’ll see two hardware units. Instead, one physical access point (or router or adapter) has two hardware components on the inside.
Dual-band broadcasters (routers, access points) are generally concurrent (or true) dual-band, meaning they can work on both bands simultaneously. There were once selectable dual-band broadcasters — supporting the obsolete 802.11a and 802.11b/g standards — that operate on one band at a time.
All receivers (adapters/clients), dual-band or not, can only connect to a broadcaster using one band at a time.
Combined speed designation
With Wi-Fi 4, networking vendors use the N designations, where N is short for 802.11n.
For example, they called a dual-band dual-stream (2×2) Wi-Fi 4 router an N600 router. The number following N is the combined ceiling speeds of both bands (300Mbps on the 2.4Ghz and 300Mbps on the 5Ghz). Similarly, three-stream (3×3) routers are now classified as N900.
This type of naming continues with newer Wi-Fi standards.
MIMO stands for multiple-input and multiple-output. It allows a pair of broadcaster and receiver to handle multiple data streams at a time. The more streams there are, the faster the connection is.
Again, MIMO started with Wi-Fi 4 (802.11n) and works on both 2.4GHz and 5GHz frequency bands. Later on, MIMO is often referred to as single-user MIMO or SU-MIMO, thanks to the introduction of MU-MIMO or multi-user multiple-input and multiple-output in Wi-Fi 5.
Wi-Fi Protected Setup (WPS)
First introduced in 2006 by Cisco, WPS became popular with Wi-Fi 4. This is a quick way to allow a client to connect to a Wi-Fi network via a press of a button on the router and then on a client.
WPS saves you from the hassle of manually typing in the Wi-Fi password, but in some instances, it could pose security risks. Nonetheless, it’s available in later standards.
Wi-Fi Protected Access (WPA)
Wi-Fi 4 is also when the new Wi-Fi protected setup Wi-Fi Protected Access (WPA) became widely adopted.
Officially available in 2003, WPA replaced the Wired Equivalent Privacy (WEP) security method laden with vulnerabilities.
WPA uses a common configuration called WPA-PSK (Pre-Shared Key). The security keys used by this method are 256-bit in length, much better than the 64-bit and 128-bit keys of WEP.
Initially, for encryption, WPA uses the Temporal Key Integrity Protocol (TKIP), which employs a dynamic per-packet key system that’s more secure than WEP’s fixed key system. Later on, WPA gets an even better encryption standard called Advanced Encryption Standard (AES).
During its entire life, WPA allows users to choose between TKIP and AES. Besides WPA, Wi-Fi 4 hardware also supports WEP for backward compatibility since some legacy clients don’t support WPA.
While secure, WPA is vulnerable to hacking, especially via Wi-Fi Protected Setup (WPS) mentioned above.
Wi-Fi 5 (802.11ac)
This standard operates only on the 5GHz band and the base single stream speed of around 433Mbps (80MHz) and can deliver up to four streams at a time (4×4), hence up to around 1733Mbps (4 x 433Mbps) speed.
Some Wi-Fi 5 broadcaster support the new 160MHz to deliver even faster speed. However, very few Wi-Fi 5 clients support this channel width.
On the 5GHz band, the standard is backward compatible with Wi-Fi 4. Also, a Wi-Fi 5 router/access point always includes a Wi-Fi 4 access point on the 2.4GHz band. For this reason, any Wi-Fi 5 broadcaster will support all existing Wi-Fi clients.
With Wi-Fi 5 comes the addition of:
- Traditional Tri-band
- Beam Forming
- The adoption of the WPA2 security method
- Wi-Fi mesh system
Generally, this means a broadcaster has three access points of different bands.
Traditionally, this means it has one 2.4GHz band and two of 5GHz bands, all working simultaneously. A tri-band broadcaster can serve more 5GHz clients at the same time than a dual-band router before slowing down.
There’s now a new type of tri-band with the introduction of Wi-Fi 6E — more below.
Wi-Fi 5‘s AC designations
Similar to the N designations above, networking vendors now combine the speeds of all bands into new names for Wi-Fi 5 routers. These names start with AC, where AC is short for 802.11ac.
Different vendors might use different numbers depending on how they decide to round up (or down) the total bandwidth, mostly for marketing purposes. So, they are not consistent throughout the industry.
Keep in mind that the numbers following AC are not the top speed of a single connection but the total bandwidth of all bands.
That’s like calling your flying car (when you have one!), which can run at 60 miles per hour and fly at 120Mph, a a180Mph vehicle. That is misleading since the car can only run or fly at a time. But networking vendors love to use this as a marketing ploy.
Beamforming is a feature where the broadcaster automatically focuses its signals in a specific direction of a receiver to increase efficiency and, therefore, speed.
Beamforming is only available on the broadcaster side, and it’s generally hard to gauge its effectiveness.
Commercially available in 2006, the WPA2 is an improved version of WPA. The Biggest change is the mandatory use of the AES encryption method and the introduction of the Counter Cipher Mode with Block Chaining Message Authentication Code Protocol (CCMP) as the replacement for TKIP.
Wi-Fi 5 hardware still supports WPA for backward compatibility. The support for WEP was also available initially but slowly phased out in newer hardware.
While WPA2 is much more secure than WPA, it’s not 100% hack-proof and is also succeptible to hacking, again via the use of WPS. The chance of getting a WPA2 security method hack is minimal, however.
This feature is part of Wi-Fi 5 Wave 2 — an enhanced version of 802.11ac. MU-MIMO allows multiple devices to receive various data streams at the same time.
More specifically, in a MIMO network, the broadcaster handles just one Wi-Fi client at a time, first come first served. So if you have multiple clients, they have to stay in line and take turns to receive data packages. It’s like when there’s just one bartender in the club.
On the other hand, in an MU-MIMO network, the broadcaster can serve up to four (possibly more in the future) Wi-Fi clients simultaneously. It’s like having a few bartenders in the club.
That said, it’s important to note that even in a MIMO network, a router can switch between clients quite fast, and most of the time, you won’t experience any delay or slow down at all.
Consequently, unless you have many — a dozen or so — simultaneously active clients, you won’t see the benefit of MU-MIMO. Also, this feature only works on the downlink and only on the 5GHz band.
Most routers, if not all, new router and access points support MU-MIMO.
Wi-Fi mesh system
Wi-Fi mesh systems are when you use multiple broadcasters together to form a seamless network to cover a large property. This type of Wi-Fi solutions starts with Wi-Fi 5, specially with the eero which was first introduced in 2016.
Mesh systems comes in all different flavors to deliver different speed and coverage grades to fit different needs. You can read more about them in this post.
First introduced in 2009 as WiGig, this standard was initially one on its own and didn’t become part of the Wi-Fi ecosystem until 2013.
802.11ad operates at 60 GHz and has super-fast wireless speeds of up to 7 Gbps.
However, it has a concise range of fewer than 10 feet (3m). It also can’t penetrate walls or objects, making it impractical as a wireless networking standard.
So, the 802.11ad was available briefly as a docking solution for a laptop — a quick way to connect devices at a close distance, within a line of sight. Due to this extreme shortcoming, this standard has suffered from low adoption rates.
An 802.11ad router, such as the Netgear Nighthawk X10, always includes an 802.11ac and 802.11n access points to work with existing Wi-Fi clients. But, generally, you can probably skip this standard.
Wi-Fi 6 (802.11ax)
802.11ax is the latest generation of Wi-Fi and became commercially in early 2019.
This new standard operates in both 5GHz and 2.4GHz bands. On the former, it supports the 160MHz channel and has the base sing-stream speed of 600Mbps.
So far, on the broadcaster side, we have a 4×4 routers that can deliver up to 4800Mbps of wireless bandwidth. On the receiver side, tough, we only have a 2×2 adapter.
The speeds of Wi-Fi 6 are a complicated matter, and I wrote a long post on the subject. Other than that, with this standard, there are a few new noteworthy features, including
- Target Wake Time
OFDMA – More efficiency
Wi-Fi 6 uses new a new technology called orthogonal frequency-division multiple access (OFDMA), which is a mouthful for frequency division multiplexing.
Specifically, the technique divides each channel into many sub-channels of different frequencies of their own. These “mini” frequencies stack on top of one another to deliver much better efficiency.
You can think of OFDMA as an enhanced version of MU-MIMO. If MU-MIMO is like having multiple bartenders (instead of just one as in MIMO), OFDMA takes it up a considerable notch by using robotic bartenders; each can serve numerous customers at a time.
Target Wake Time – Better battery life
Wi-Fi 6 further improves battery life compared to Wi-Fi 5 (802.11ac) partly because it requires less time to transmit the same amount of data. Most significantly, however, it has a new feature calledWake time scheduling orTarget Wake Time (TWT).
TWT allows a Wi-Fi adapter to quickly go to sleep when idle (even for a very brief time) and automatically wake up when needed. It’s similar to having a car that automatically turns off its engine at a red light and automatically starts when you step on the gas.
This is the latest security method that was introduced in 2018 to do away with WPA2. Initially, not all Wi-Fi 6 devices support WPA3 but all will via firmware update. Some latest Wi-Fi 5 hardware also support this method as an option.
Wi-Fi 6E is the latest Wi-Fi standard that was commerically avaliable in 2021. It’s not really stadnard of itself but rather an extension of Wi-Fi 6.
Wi-Fi 6E has all the attributes of Wi-Fi 6 but with one exception: It uses an entirely new 6GHz frequency band. As a result, it has more spectrum space and can deliver up to seven 160MHz channels, or fourteen 80MHz ones.
In terms of speed, Wi-Fi 6E has the same ceiling speed as Wi-Fi 6, but it can deliver this speed more easily. In return, Wi-Fi 6E has a shorter range than Wi-Fi 6.
Like the move to the 5GHz band in Wi-Fi 4, Wi-Fi 6E requires new hardware. As a result, we now have a new type of tri-band where hardware devices need to include all three bands (2.4GHz, 5GHz, and 6GHz) to make sure they can work with one another.
Mandatory WPA3 and Enhance Open (OWE) protocol
In terms of security, with Wi-Fi 6E, WPA3 is now mandatory. All 6GHz devices must use it and no longer support WPA2 or any earlier security method. Wi-Fi 6E broadcaster still supports WPA2 and even WPA for their 5GHz and 2.4Ghz bands, however, for backward compatibility.
On top of that, for those who don’t need or want to password-protect their Wi-Fi network, Wi-Fi 6E now uses Wi-Fi Alliance’s Wi-Fi CERTIFIED Enhanced Open protocol, which “provides protections in scenarios where user authentication is not desired or distribution of credentials impractical.”
Examples of such places are hotels, cafes, or airports. The idea of Enhanced Open, also called Opportunistic Wireless Encryption (OWE) per some vendors, is that it encrypts each connection to an open Wi-Fi network with a known cryptography mechanism. As a result, OWE-supported parties get protection against hacking. However, when a non-OWE client connects to an OWE broadcaster, it’ll treat it as a normal open network.
Wi-Fi 6E is slated to be widely available starting in late 2021. For more, I wrote about it in great details in this post.