What are the main wifi protocols? All you need to know

On this occasion we explain in detail what the main Wifi protocols are . Until a few years ago it was only possible to interconnect computers using cables. This type of connection is quite popular, but it has some limitations, for example: you can only move the equipment up to the cable's reach limit; High equipment environments may require adaptations in the building structure for the passage of cables; In a home, it may be necessary to drill holes in the wall for cables to reach other rooms; constant or incorrect manipulation can cause the cable connector to be damaged. Fortunately, Wi-Fi wireless networks emerged to remove these limitations.

Index of contents

The use of this type of network is becoming increasingly common, not only in domestic and professional settings, but also in public places (bars, cafes, shopping malls, bookstores, airports, etc.) and in academic institutions.

For this reason, we are going to look at the main characteristics of Wi-Fi technology and explain a little about how it works. As it could not stop being, you will also know the differences between the Wi-Fi standards 802.11b, 802.11g, 802.11n and 802.11ac.

What are the main Wifi protocols? What is Wi-Fi?

Wi-Fi is a set of specifications for wireless local area networks (WLAN), based on the IEEE 802.11 standard. The name "Wi-Fi" is taken as an abbreviation for the English term "Wireless Fidelity", although the Wi-Fi Alliance, the entity primarily responsible for licensing technology-based products, has never affirmed such a conclusion. It is common to find the name Wi-Fi written as "wi-fi", "Wi-fi" or even "wifi". All of these names refer to the same technology.

With Wi-Fi technology, it is possible to implement networks that connect computers and other devices (smartphones, tablets, video game consoles, printers, etc.) that are geographically close.

These networks do not require the use of cables, since they carry out the transmission of data by means of radio frequency. This scheme offers several advantages, among them: it allows the user to use the network at any point within the transmission range; enables quick insertion of other computers and devices on the network; prevents the walls or structures of the real estate property from being plastic or adapted for the passage of cables.

The flexibility of Wi-Fi is so great that it became feasible to implement networks that make use of this technology in the most varied places, mainly due to the fact that the advantages mentioned in the previous paragraph often result in lower costs.

Thus, it is common to find Wi-Fi networks available in hotels, airports, highways, bars, restaurants, shopping malls, schools, universities, offices, hospitals, and many more places. To use these networks, the user only needs to have a laptop, smartphone or any Wi-Fi compatible device.

A bit of the history of Wi-Fi

The idea of ​​wireless networks is not new. The industry has been concerned about this issue for a long time, but the lack of standardization of standards and specifications proved to be an obstacle, after all, several research groups were working with different proposals.

For this reason, some companies such as 3Com, Nokia, Lucent Technologies and Symbol Technologies (acquired by Motorola) came together to create a group to deal with this issue and, thus, the Wireless Ethernet Compatibility Alliance (WECA) was born in 1999, which was renamed the Wi-Fi Alliance in 2003.

As with other technology standardization consortia, the number of companies that join the Wi-Fi Alliance is constantly increasing. WECA went on to work with the IEEE 802.11 specifications, which are actually not very different from the IEEE 802.3 specifications. This last set is known by the name of Ethernet and simply consists of the vast majority of traditional wired networks. Essentially, what changes from one standard to the other are its connection characteristics: one type works with cables, the other by radio frequency.

The advantage of this is that it was not necessary to create any specific protocol for wireless network communication based on this technology. With this, it is even possible to have networks that use both standards.

But WECA still had to deal with another question: an appropriate name for the technology, that was easy to pronounce and that allowed a quick association with its proposal, that is, wireless networks. To do this, it hired a company specialized in brands, Interbrand, which ended up not only creating the name Wi-Fi (probably based on that term "Wileress Fidelity"), but also the technology logo. The denomination has been so widely accepted that WECA decided to change its name in 2003 to the Wi-Fi Alliance, as reported.

Wi-Fi operation

At this point in the text, you're naturally wondering how Wi-Fi works. As you already know, the technology is based on the IEEE 802.11 standard. But this does not mean that all products that work with these specifications will also be Wi-Fi.

In order for a product to receive a seal with this brand, it must be evaluated and certified by the Wi-Fi Alliance. This is a way to guarantee the user that all products with the W i-Fi Certified seal follow functionality standards that guarantee inter-operability with other equipment.

However, this does not mean that devices without a seal will not work with devices that do (still, it's always best to choose certified products to avoid risks and problems).

The 802.11 standard establishes standards for the creation and use of wireless networks. Transmission of this type of network is done by radio frequency signals, which spread through the air and can cover areas in the house of hundreds of meters.

Since there are a wide variety of services that can use radio signals, it is essential that each one act according to the requirements established by the government of each country. This is a good way to avoid inconvenience, especially interference.

There are, however, some frequency segments that can be used without the need for direct approval from the appropriate entities of each government: the ISM (Industrial, Scientific and Medical) bands, which can operate, among others, with the following intervals: 902 MHz - 928 MHz; 2.4 GHz - 2.485 GHz and 5.15 GHz - 5.825 GHz (depending on the country, these limits may vary).

SSID (Service Set Identifier)

We are going to know the most important versions of 802.11, but before, to facilitate understanding, it is convenient to know that, for such a network to be established, it is necessary that the devices (also called STA) be connected to the devices that facilitate the access. These are generically called Access Point (AP). When one or more STAs connect to an AP, there is therefore a network, which is called the Basic Service Set (BSS).

For security reasons and the possibility that there is more than one BSS in a certain place (for example, two wireless networks that were created by different companies in an event area), it is key that each receive an identification called Service Set Identifier (SSID), a set of characters that, after defined, is inserted into the header of each data packet on the network. In other words, the SSID is the name given to each wireless network.

Wi-Fi protocols

The first version of the 802.11 standard was released in 1997, after approximately 7 years of studies. With the emergence of new versions (to be addressed later), the original version became known as 802.11-1997 or 802.11 legacy.

As it is a radio frequency transmission technology, the IEEE (Institute of Electrical and Electronic Engineers) determined that the standard could operate in the frequency range of 2.4 GHz and 2.4835 GHz, one of the aforementioned ISM bands.

Its data transmission rate is 1 Mb / s or 2 Mb / s (megabits per second), and it is possible to use the Direct Sequence Spread Spectrum (DSSS) and Frequency Hopping Spread Spectrum (FHSS) transmission techniques.

These techniques allow transmissions using multiple channels within a frequency, however DSSS creates multiple segments of the transmitted information and simultaneously sends them to the channels.

The FHSS technique, in turn, uses a “frequency hopping” scheme, where the transmitted information uses one frequency in a certain period and, on the other, uses another frequency.

This feature makes the FHSS have a slightly lower data transmission rate, on the other hand, it makes the transmission less susceptible to interference, since the frequency used constantly changes. DSSS ends up being faster, but is more likely to suffer interference, once all channels are used at the same time.

802.11b

An update to the 802.11 standard was released in 1999 and was called 802.11b. The main feature of this version is the possibility of establishing connections at the following transmission speeds: 1 Mb / s, 2 Mb / s, 5.5 Mb / s and 11 Mb / s.

The frequency range is the same used by the original 802.11 (between 2.4 and 2.4835 GHz), but the transmission technique is limited to the spectrum spread by direct sequence, since the FHSS ends up not taking into account the standards established by the Federal Communications Commission (FCC) when used in transmissions with rates greater than 2 Mb / s.

To work effectively at speeds of 5.5 Mb / s and 11 Mb / s, 802.11b also uses a technique called Complementary Code Keying (CCK).

The coverage area of ​​an 802.11b transmission can theoretically be up to 400 meters in open environments and can reach a range of 50 meters in closed places (such as offices and homes).

It is important to note, however, that the range of the transmission may be influenced by a number of factors, such as objects that cause interference or impede the propagation of the transmission from where they are.

It is interesting to note that, to keep transmission as functional as possible, the 802.11b standard (and successor standards) can cause the data transmission rate to decrease to its minimum limit (1 Mb / s) as a station is further from the access point.

The reverse is also true: the closer to the access point, the higher the transmission speed can be.

The 802.11b standard was the first to be adopted on a large scale, being, therefore, one of the people responsible for the popularization of Wi-Fi networks.

802.11a

The 802.11a standard was released in late 1999, around the same time as the 802.11b version.

Its main characteristic is the possibility of operating with data transmission rates in the following values: 6 Mb / s, 9 Mb / s, 12 Mb / s, 18 Mb / s, 24 Mb / s, 36 Mb / s, 48 Mb / s and 54 Mb / s. The geographical range of its transmission is approximately 50 meters. However, its operating frequency is different from the original 802.11 standard : 5 GHz, with 20 MHz channels within this range.

On the one hand, the use of this frequency is convenient because it presents less possibilities of interference, after all, this value is little used. On the other, it can bring certain problems, since many countries do not have regulations for that frequency. Additionally, this feature can cause communication difficulties with devices that operate on 802.11 and 802.11b standards.

An important detail is that instead of using DSSS or FHSS, the 802.11a standard makes use of a technique known as Orthogonal Frequency Division Multiplexing (OFDM). In it, the information to be transferred is divided into several small data sets that are transmitted simultaneously on different frequencies. These are used in such a way that one interferes with the other, making the OFDM technique work quite satisfactorily.

Despite offering higher transmission rates, the 802.11a standard did not become as popular as the 802.11b standard.

802.11g

The 802.11g standard was released in 2003 and is known as the natural successor to the 802.11b version, as it is fully compatible with it.

This means that a device that works with 802.11g can communicate with another one that works with 802.11b without any problem, except for the fact that the data transmission rate obviously limits the maximum allowed by the latter.

The main attraction of the 802.11g standard is to be able to work with transmission rates of up to 54 Mb / s, as it happens with the 802.11a standard.

However, unlike this version, the 802.11g operates at frequencies in the 2.4 GHz band (20 MHz channels) and has almost the same coverage power as its predecessor, the 802.11b standard.

The transmission technique used in this version is also OFDM, however, when communicating with an 802.11b device, the transmission technique becomes DSSS.

802.11n

Development of the 802.11n specification began in 2004 and ended in September 2009. During this period, various devices compatible with the unfinished version of the standard have been released.

The main feature of the 802.11n protocol is the use of a scheme called Multiple-Input Multiple-Output (MIMO), capable of considerably increasing data transfer rates by combining various transmission routes (antennas). With this, it is possible, for example, the use of two, three or four transmitters and receivers for the operation of the network.

One of the most common configurations in this case is the use of access points that use three antennas (three transmission paths) and STAs with the same number of receivers. Adding this feature in combination with refining its specifications, the 802.11n protocol is capable of transmitting in the 300 Mb / s range, theoretically, it can reach speeds of up to 600 Mb / s. In the simplest transmission mode, with one transmission path, 802.11n can reach 150 Mb / s.

Regarding its frequency, the 802.11n standard can work with the 2.4 GHz and 5 GHz bands, which makes it compatible with the previous standards, even with 802.11a. Each channel within those tracks is, by default, 40 MHz wide.

Its standard transmission technique is OFDM, but with certain modifications, due to the use of the MIMO scheme, being, therefore, often called MIMO-OFDM. Some studies suggest that its coverage area can exceed 400 meters.

802.11ac

The successor to 802.11n is the 802.11ac standard, the specifications of which have been almost fully developed between 2011 and 2013, with the final approval of its characteristics by the IEEE in 2014.

The main advantage of 802.11ac is in its speed, estimated at up to 433 Mb / s in the simplest mode. But, in theory, it is possible to make the network exceed 6 Gb / s in a more advanced mode that uses multiple transmission paths (antennas), with a maximum of eight. The trend is for the industry to prioritize equipment with the use of up to three antennas, making the maximum speed around 1.3 Gb / s.

Also called WiFi 5G, 802.11ac works on the 5 GHz frequency, being that, within this range, each channel can have, by default, the width of 80 MHz (160 MHz optional).

The 802.11ac protocol also has the most advanced modulation techniques. More precisely, it works with the MU-MUMO (Multi-User MIMO) scheme, which allows signal transmission and reception from various terminals, as if they were working collaboratively, on the same frequency.

It also highlights the use of a transmission method called Beamforming (also known as TxBF), which is optional in the 802.11n standard: it is a technology that allows the transmitting device (such as a router) to evaluate communication with a client device to optimize transmission in your direction.

Other 802.11 standards

The IEEE 802.11 standard has had (and will have) other versions in addition to those mentioned above, which have not become popular for various reasons.

One of them is the 802.11d standard , which is applied only in some countries where, for some reason, it is not possible to use some of the other established standards. Another example is the 802.11e standard, whose main focus is the QoS (Quality of Service) of transmissions, that is, the quality of service. This makes this model interesting for applications that are severely affected by noise (interference), such as VoIP communications.

There is also the 802.11f protocol, which works with a scheme known as a relay that, in short, makes one device disconnect from a weak signal Access Point and connect to another, stronger signal Access Point, within the same network. The problem is that some of the factors can cause this procedure to not take place properly, causing inconvenience to the user. 802.11f specifications allow for better interoperability between access points to lessen these problems.

The 802.11h standard also deserves to be highlighted . Actually, this is just a version of 802.11a that has control and frequency modification capabilities. This, because the 5 GHz frequency (used by 802.11a) is applied in a variety of systems in Europe.

There are several other features, but unless for specific reasons, it is advisable to work with the most popular versions, preferably with the most recent one.

Final words

This article made a basic presentation of the main features that Wi-Fi implies. Their explanations can help anyone who wants to understand a little more about the operation of wireless networks that are based on this technology and that can serve as an introduction for those who want to go deeper into the subject.

As you always know, we recommend reading the best routers on the market and the best PLCs of the moment. They are fundamental readings to acquire a good wireless Wi-Fi system. What did you think of our article on Wifi protocols? Which one do you currently use at home or work?