Introduction to Wireless Networking

What is WiFi?

WiFi is a family of wireless network protocols that are based on the IEEE 802.11 standards, all of which are commonly used for spreading a Local Area Network (LAN) to devices requiring internet access. A wireless LAN stands out in that it uses radio waves rather than fixed copper or Fibre cabling.

Statistically, WiFi networks are the most widely used computer networks in the world, used globally in homes, small offices and enterprises to link client devices such as laptops, tablets, mobile phones, smart TVs and printers via a wireless router or Access Point to an Internet or intranet service.

WiFi primarily uses two frequencies, 2.4GHz (Gigahertz) and 5GHz, both of which are subdivided into multiple channels that can be shared between networks. However, only one transmitter can transmit locally on a single channel at a time. When deciding between using 5GHz or 2.4GHz, you must consider the environment: 2.4GHz has greater range and surface-penetration, owing to its lower frequency, so it can perform better across longer distance and through multiple walls. The trade-off however is a lower throughput capacity and wireless channel congestion when there are several clients connecting to the network.

5GHz is better suited for faster throughput requirements, and preventing channel congestion, which is possible due to using a higher frequency. This does however mean that more power is required and the signal is also not as good at penetrating through solid objects such as 2.4GHz. It’s worth noting that 5GHz radiates in a scatter format so it can provide better coverage, at least when you are close to the original wireless signal, whereas 2.4GHz tends to be more directional in coverage.

Most modern devices support both 2.4GHz and 5GHz (referred to as dual-band). Typically, what happens is that when you’re close-by to a wireless signal, your device will choose the 5GHz SSID and then switch to the 2.4GHz SSID as you move away and the signal degrades (presuming both SSIDs are remembered by the device). When WiFi is used to provide a wireless link between two points it is recommended to use 5GHz as you are less likely to encounter objects and thus maintain a higher amount of throughput.

WiFi Standards

WiFi has been based on various standards over the years, beginning with WiFi 1 (802.11a) and currently culminating with the newest standard, WiFi 7 (802.11be).

The 3 standards most commonly seen nowadays are WiFi 5, WiFi 6 and WiFi 7 – all of which are at least dual-band and so use both 2.4GHz and 5GHz. There are various technical differences between the standards but probably the simplest and most obvious difference is that newer standards have much faster throughput speeds. Note that a WiFi standard needs to be supported by a client device as well as the wireless transmitter in order to work to its highest level, meaning for example; you cannot achieve WiFi 7 speeds if your laptop only supports up to WiFi 5.

Typical Wireless Usage

The two primary uses for WiFi are for spreading wireless signal around a local area, like a building or garden, and for creating a long-range point-to-point network link, such as when trying to get internet to an outbuilding several hundred metres away. Unobstructed line-of-sight is crucial with these point-to-point links because obstructions can prevent the signal from reaching its intended destination. Some surfaces will reflect signals whilst others tend to absorb them – even putting your hand in between some of these directional links can be enough to block the connection.

Obstructions are still a problem that WiFi has to deal with for omni-directional spread, such as when being used in a house and spreading across multiple rooms. Sometimes multiple WiFi transmitters will be needed to spread the signal sufficiently around a building – you could use WiFi Access Points for this. When it comes to setting up these kinds of networks, WiFi transmitters capable of broadcasting 5GHz signals will usually outperform 2.4GHz-only devices, 5GHz signals have better scatter making it theoretically better for indoor operation where it needs to reach remote rooms. You can read more information on 5GHz wireless in our "5GHz Frequency Bands" Article.

If you don't have line of sight, it is possible to bridge using omni-directional bridging units, but the success of the wireless link will be incredibly environmental dependent.

Wireless Range

You will see specifications for different brands of wireless networking devices quoting wildly different ranges but take these claims of huge range with a pinch of salt, as unless the manufacturers have got something very wrong, or are operating at illegal power output levels, then products from different sources will behave pretty much the same within similar parameters. Any variations in the true range between products, assuming the comparison is done with products running at similar power levels, comes down to factors such as antenna gain, as this alters beam spread and receive sensitivity. The receive sensitivity refers to the ability to cope with multi-path reflection effects, for more information please see our article about line-of-sight signal propagation.

Below are some examples of expected distances in an outdoor scenario with clear line of sight, although there can be no guarantee that you will achieve these numbers, nor that the figures represent maximum or minimum limits, because environmental factors vary unpredictably and will always have an impact. The examples are what you might expect to achieve using 'off-the-shelf' wireless devices and a standard 100mW access point with a given antenna gain at both ends, with an assumed receiver sensitivity of about –83dB.

The effective gain considers the antenna gain and any losses in cabling. For instance, if you have a 12dB antenna but lose 5dB in the cable leading from it then you now have an effective gain of 7dB.You should also ensure that you do not exceed any legal power density limits which apply in your region.

Metal external antennas can make great lightning conductors, so consider what equipment you are putting at risk if you choose not to invest in a lightning arrester. On paper, the distance figures for 5GHz operation may not look that much better when compared to 2.4GHz but it's worth remembering that the permitted power output levels for 5GHz are 10 times those for 2.4GHz wireless (100mW vs 1W), which means that if you stick to the legal power limits, then the practical range for 5GHz devices is further than the equivalent 2.4GHz equipment.

Antenna Gain

An antenna produces gain by focusing the available radio energy in one direction, meaning that the more gain an antenna has, the thinner the beam angle. This is ideal for directional antennas pointing at a specific target within visible range, for example an outbuilding across a field, but can be unreliable in urban scenarios where there are plenty of objects for the signal to reflect off.

Alternatively, an omni-directional antenna radiates around itself in a disc pattern, stealing power from above and below, making it better suited in areas with lots of objects because it can pick up signals deflected from all sorts of angles. Omni-directional antenna are ideal for most scenarios where WiFi needs to be broadcasted for devices like phones and laptops to connect to, because the signal will be spread across a wide area rather than a single narrow line.

As an example of the shapes of these antenna radio patterns, an 0dB antenna radiates equally over a complete sphere. 3dB represents a doubling of radiated power, so you could have a 3dB directional antenna radiating its signal into one half of that sphere. In other words, a 3dB omni-directional antenna would have a radiation pattern in the shape of a sphere with a cone removed from the top and bottom.

MIMO Receivers

Unlike older wireless standards such as WiFi 2 or WiFi 3, newer WiFi standards have the capability to use multiple streams for sending and receiving signals simultaneously using a technology called MIMO (Multi In Multi Out). This means that, for example, WiFi 5 devices using 80MHz channels can have 433Mbps per channel.

There are several advantages to breaking the signal up like this, such as reducing packet collision when multiple data streams are happening concurrently. Different modes implement the signal differently; some modes send the same stream over each antenna in order to improve signal reliability, and other modes split the data stream in order to improve throughput. The method that the signal is split or implanted is set by the MCS number, which is normally left as 'Auto' and a WiFi unit will choose the mode that is best for speed and stability.

WiFi 7 - 802.11be

WiFi 7, also known as 802.11be, is the newest wireless standard at the time of writing, releasing in late 2024, and features several impressive technical upgrades from its predecessors. The most significant technical difference is that WiFi 7 uses a third frequency band, 6GHz, on top of the usual 2.4GHz and 5GHz. As a higher band, not only is 6GHz capable of much faster data rates but it’s also a much lesser-used spectrum and therefore will encounter much less radio interference.

There are various other key improvements with WiFi 7 on top of this, such as being able to use all three bands simultaneously and supporting 16x16 MU-MIMO for faster speeds when being used by many different devices at once. All of this adds up to the simplest way of measuring how powerful it is compared to other WiFi standards – while WiFi 5 can achieve maximum speeds of 3.5Gbps and WiFi 6 can reach 9.6Gbps, WiFi 7 can reach maximum speeds of 46Gbps which is 4.8 times faster. It will take a bit of time before WiFi 7 becomes widespread among both WiFi transmitters and client devices that receive the WiFi, but when it does it will surely revolutionise the performance of WiFi both domestically and professionally.

Last updated January 2025.