As the saying goes “home is where Wi-Fi connects automatically”. As much focus as smartphone manufacturers put into advertising the next generation of cellular connectivity on their phones, many of us spend most of our day connected to the Internet via Wi-Fi.
Wi-Fi is certainly not the first method of transferring data between nearby devices wirelessly. Early PDAs used infrared, which allowed them to synchronize calendar appointments and e-mail inboxes, for example. However, infrared is directional, so to connect your PDA and PC, you had to aim at the IR adapter and hold still for several seconds. The easiest way to do this was to have both the device and the adapter stationary on a desk. Technically, no wires were connected, but there was little difference in mobility.
PDAs were among the first pocket devices to get Wi-Fi connectivity, although they didn’t always come with that feature from the factory – CF and SD cards were used as modular add-ons that could enable Wi-Fi, GSM, Bluetooth and other functionality.
Not surprisingly, the first mobile devices to have Wi-Fi on board were Windows Mobile PDAs. Wi-Fi connected you to the Internet (and the company intranet) and could sync emails, calendars, and so on, mostly business-related tasks.
Bluetooth is another early local wireless connectivity option. However, it was slower than Wi-Fi (which mattered more to laptops than PDAs, but still) and had lower range (at least with the commonly available adapters).
Wi-Fi is limited by law to 100mW transmit power, and the rule of thumb is that you can get up to 100m of range under ideal conditions (ie outdoors with a clear view). Interesting note – in 2007 researcher Ermanno Pietrosemoli managed to transmit 3MB of data at a speed of 3Mbps between the mountain peaks of El Aguila and Platillon in Venezuela, which are separated by 382km/238mi. Some long-range Wi-Fi connections are in use today to connect remote locations in the mountains, but these are the exceptions to the rule.
A 382 km long link between the peaks of El Águila and Platillon was established in 2007
Before we continue, we should cover the naming of Wi-Fi. First, “Wi-Fi” stands for “Wireless Fidelity” (similar to Hi-Fi) and was invented by a brand consulting firm that was hired to come up with something “a little catchier than ‘IEEE 802.11b Direct Sequence'”. The technology is part of the IEEE 802.11 family and different versions attach a letter, e.g. 802.11b.
But it’s not very catchy, is it? Then in 2018 the Wi-Fi Alliance changed things to a simpler and more user-friendly naming scheme – Wi-Fi 802.11n became Wi-Fi 4 and versions after that adopted subsequent numbers. Check the table below. Note that 802.11g and earlier were retroactively renamed, since “Wi-Fi 4” doesn’t make much sense without them.
| Generation | IEEE standard | Accepted | Maximum connection speed (Mbit/s) | Radio frequency (GHz) |
| WiFi 1 | 802.11b | 1999 | 1 to 11 | 2.4 |
| WiFi 2 | 802.11a | 1999 | 6 to 54 | 5 |
| WiFi 3 | 802.11 g | 2003 | 6 to 54 | 2.4 |
| WiFi 4 | 802.11n | 2008 | 72 to 600 | 2.4/5 |
| WiFi 5 | 802.11ac | 2014 | 433 to 6,933 | 5 |
| WiFi 6 | 802.11ax | 2019 | 574 to 9,608 | 2.4/5 |
| Wi-Fi 6E | 2020 | 6 | ||
| WiFi 7 | 802.11be | 2024 | 1,376 to 46,120 | 2.4/5/6 |
Let’s look at some of the major developments in Wi-Fi. Early versions operate in the 2.4GHz band, the so-called ISM radio band (ISM stands for Industrial, Scientific and Medical, as these were the first uses for the band). Since the rules in this band are quite loose, there are many units that work there. Including microwave ovens, which is at least part of the reason why 2.4GHz is the wild west of wireless. Early on, when a microwave started blasting 1000W at your lunch, Wi-Fi and Bluetooth connections became briefly unreliable. Modern units are much more resistant (and modern ovens are better insulated).
Wi-Fi 4 (802.11n) is probably the biggest improvement to Wi-Fi since its inception. Most Wi-Fi before 2008 operated in 2.4 GHz, although 5 GHz was supported from the beginning – Wi-Fi 1 (802.11b) operated in 2.4 GHz, Wi-Fi 2 (802.11a) in 5 GHz. Both standards date from 1999, although 2.4GHz was the most widely used band. But as mentioned above, it got very, very crowded and the connection suffered.
Wi-Fi 4 reintroduced support for the 5GHz band. It was less crowded and could fit larger channels. Initially, channels in the 2.4 GHz band were only 5 MHz wide, later support for 20 MHz channels was added. That created a problem, but only four 20Mhz channels can fit in the 2.4GHz band without overlapping (ie without interfering with each other).
This is why you should position your Wi-Fi channels – the best channels to choose are 1, 6 and 11 (there are channels 12 and 13, but they are not available everywhere). In comparison, the 5GHz band has enough room for at least 23 non-overlapping 20MHz channels.
Anyway, Wi-Fi 4 added support for pairing two 20MHz channels to double the speed. Then came Wi-Fi with additional support for 80MHz channels and the ability to combine two such channels for a total of 160MHz. Of course, it only worked in 5GHz, since 160MHz is more than the total bandwidth allocated to Wi-Fi in the 2.4GHz band.
Wi-Fi 4 also introduced support for Multiple Input, Multiple Output, aka MIMO. This allowed devices (both transmitters and receivers) to have multiple antennas, which had two major advantages – it increased range and speed.
These days, even the 5GHz band is pretty crowded, so Wi-Fi 6 moved up and opened up the 6GHz band. This technology is called Wi-Fi 6E and in the US (it varies slightly from country to country) it has access to a full 1,200 MHz bandwidth. There’s plenty of room here, the 6E fits seven 160MHz channels, although the range is limited at lower frequencies. This is a blessing and a curse – it helps ease congestion, but low range means you may need more access points or to build a mesh network.
There’s a lot of cool technology that we haven’t covered here. For example, Wi-Fi 6 introduced Target Wake Time, which reduces power consumption by ensuring that the mobile device is only awake when it needs to send or receive data and can immediately go back to sleep afterwards.
There’s also the topic of security, from the woeful WEP to the WPA standards that replaced it. The convenient WPS feature also had its problems (WPS allows users to connect a new device to the network by simply pressing a button on the access point and the device).
We also haven’t covered WiGig, a 60GHz standard that we’ve seen in some mobile devices as a way to transmit high-resolution, low-latency video to a screen without the use of wires. But this post is already getting pretty long, so we’ll leave that for another time.
The most interesting thing on the horizon is Wi-Fi 7. Chipmakers like Qualcomm and MediaTek are already preparing for it, and we may see the first devices as early as this year. Snapdragon 8 Gen 2 and some phones powered by it claim to support Wi-Fi 7, although the standard is still in draft stages and is expected to be finished in 2024. This has happened before, the first Wi-Fi 4 devices also launched based on a draft specification of the standard. Wi-Fi 7 will provide support for 320 MHz bandwidth and speeds of up to 30 Gbps.
Do your phone and access point at home support the latest Wi-Fi version? And is it something you care about or are you happy using an older version?
