What are the types of WiFi

IEEE 802.11 / WLAN basics

IEEE 802.11 is a group of standards for a wireless network based on Ethernet. Wireless LAN (WLAN) based on IEEE 802.11 quickly found acceptance among manufacturers and consumers. In the beginning, PCs and notebooks were equipped with expansion cards. But single chips for notebooks and smartphones were quickly developed. And so a WLAN function is integrated in almost every mobile or computer-like device today. This makes the IEEE 802.11 standard the most widespread wireless network or technology for a wireless local area network (WLAN).

Since 1997 there has been a binding air interface for local radio networks for the first time with IEEE 802.11. Before that, the widespread use of local radio networks was unthinkable due to the lack of standardization and the low data transmission rate. The standard builds on the other standards of IEEE 802. Put simply, IEEE 802.11 is a type of cordless Ethernet. IEEE 802.11 defines the physical layer of the OSI layer model for a wireless LAN. Like any other IEEE 802 network, this wireless LAN is completely protocol-transparent. Wireless network cards can therefore be integrated into any existing Ethernet without any problems. With restrictions (reliability and speed) it is possible to replace a corded Ethernet connection according to IEEE 802.3 with a WLAN connection according to IEEE 802.11.

The original IEEE 802.11 standard has been continuously expanded and improved. Mainly to increase data throughput, efficiency, range and data security and to improve the cooperation between devices from different manufacturers.

WLAN (Wireless LAN) or IEEE 802.11

Occasionally the term "Wireless LAN" and the standard "IEEE 802.11" are mixed up. The difference is very simple. "Wireless LAN" is the general name for a wireless local area network. "IEEE 802.11", on the other hand, is a standard for a technical solution that enables a wireless LAN to be set up. It is therefore quite conceivable that there are other technologies with which a wireless LAN can be set up.
However, it has become generally accepted to designate a local radio network that is based on the "IEEE 802.11" standard as a wireless LAN or WLAN. Internationally, the term "Wi-Fi" is more common for wireless fidelity.

WLAN generations

The ability of WLANs with different standards, names and possible incompatibilities is incomprehensible and difficult to tell apart for normal users. Simpler names should help. Instead of the cryptic IEEE project group names, the WLAN standards also have a consecutive number. Officially, the name begins with “Wi-Fi 4” for the IEEE 802.11n standard.

  • WLAN 1 / Wi-Fi 1: IEEE 802.11 (1999)
  • WLAN 2 / Wi-Fi 2: IEEE 802.11b (1999)
  • WLAN 3 / Wi-Fi 3: IEEE 802.11g (2003)
  • WLAN 4 / Wi-Fi 4: IEEE 802.11n (2009)
  • WLAN 5 / Wi-Fi 5: IEEE 802.11ac (2014)
  • WLAN 6 / Wi-Fi 6: IEEE 802.11ax (2021)
  • WLAN 6E / Wi-Fi 6E: IEEE 802.11ax in the 6 GHz frequency range
  • WLAN 7 / Wi-Fi 7: IEEE 802.11be (?)

Unfortunately, this information is completely inadequate. Because the standard alone is not the only parameter that has an influence on the speed and performance of WLAN technology. The number of MIMO data streams supported and the number of antennas used are just as important. This allows you to differentiate between slow and fast devices much better. But it is precisely this information that is omitted from all packaging. Without a data sheet and the correct interpretation of the information contained therein, it is not possible to assess the possible speed of WLAN devices.
The speed and performance also depend on the channel width configured in the access point.

Overview: A comparison of current WLAN standards

WLAN generationWi-Fi 4Wi-Fi 5Wi-Fi 6 / 6E
IEEE standardIEEE 802.11nIEEE 802.11acIEEE 802.11ax
Maximum transfer rate *600 Mbit / s6,936 Mbit / s9,608 Mbit / s
Theoretical transfer rate **300 Mbit / s867 Mbit / s1,200 Mbit / s
Maximum range100 m50 m50 m
Frequency range2.4 + 5 GHzonly for 5 GHz2.4 + 5 GHz + 6 GHz
Maximum send / receive units4 x 48 x 88 x 8
Antenna technologyMIMO(MU-MIMO)MU-MIMO
Maximum channel width40 MHz160 MHz160 MHz
Modulation method64QAM256QAM1024QAM

* The specified maximum transmission rate corresponds to the computational maximum of the theoretical transmission rate taking into account all performance features that are provided in the respective standard. In the practical implementation, however, there are restrictions due to which this transmission rate cannot be achieved. To compare the WLAN standards, a theoretical transmission rate that is closer to the WLAN equipment in practice is more suitable.

** The specified theoretical transfer rate corresponds to the transfer rate that is usually possible with devices that can be purchased. Two antennas and a channel width of 80 MHz in the frequency range of 5 GHz are taken into account. Depending on the equipment, the value of this theoretical transfer rate can also be higher or lower.

Overview: transmission speed

default
(IEEE)
frequency
StreamsData rate with channel width
20 MHz40 MHz80 MHz160 MHz
802.112.4 GHz12 Mbit / s   
802.11b2.4 GHz111 Mbit / s   
802.11a / h / j5 GHz154 Mbit / s   
802.11g2.4 GHz154 Mbit / s   
802.11n2.4 GHz
5 GHz
1
2
3
4
75 Mbit / s
150 Mbit / s
225 Mbit / s
300 Mbit / s
150 Mbit / s
300 Mbit / s
450 Mbit / s
600 Mbit / s
  
802.11ac5 GHz1
2
3
4
5...8
  433 Mbit / s
867 Mbit / s
1,300 Mbit / s
1,733 Mbit / s
3,400 Mbit / s
867 Mbit / s
1,733 Mbit / s
2,300 Mbit / s
3,500 Mbit / s
6,936 Mbit / s
802.11ax2.4 GHz
5 GHz
1
2
3
4
5...8
144 Mbit / s
287 Mbit / s
432 Mbit / s
574 Mbit / s
287 Mbit / s
574 Mbit / s
861 Mbit / s
1,144 Mbit / s
600 Mbit / s
1,201 Mbit / s
1,801 Mbit / s
2,402 Mbit / s
up to 4,804 Mbit / s
1,201 Mbit / s
2,402 Mbit / s
3,603 Mbit / s
4,804 Mbit / s
up to 9,608 Mbit / s

Explanation of the data rates of WLAN

If you look at the information provided by manufacturers and retailers on the gross data rate of their products and compare the values ​​that are achieved in practice, it almost smells like a reason for a complaint. The fact is that the gross data rates as indicated on the product packaging and by the standard can never be achieved in practice.

You have to know that all WLAN standards of the IEEE are specified with their theoretical maximum transmission speed. In practice, however, the specified transfer rates are much lower than specified. WLANs according to IEEE 802.11g with 54 Mbit / s rarely reach more than 16 Mbit / s in practice. A WLAN according to IEEE 802.11n with 150, 300, 450 and 600 Mbit / s rarely reaches more than half of this. The IEEE 802.11ac standard promises a gross data rate of 7 GBit / s. But these values ​​depend on which radio channel width, transmission type and the number of antennas are used. But that too is pure theory. Because in practice every radio technology has to struggle with further restrictions. In practice, the typical data rates are far lower due to specific radio conditions. But even these are only guidelines. What is really possible in practice depends on the local conditions. Ceilings, walls, furniture and other wireless networks interfere with the wireless transmission of a WLAN. Depending on the environmental conditions, the number of participating stations and their distance, only a fraction of the typical data rate can be achieved.

The difference between the gross transmission speed and what is actually possible in practice is due to the fact that WLAN radio technology is a shared transmission channel that several participants must use at the same time and therefore a special procedure for access negotiates on it. The procedure called CSMA / CA regulates when a station is allowed to transmit. The other stations have to wait during this time. Then there is a break. The radio interface can therefore never be 100% assigned. For each individual participant, this means that only a fraction of the typical transmission speed remains.

WLAN standards from IEEE 802.11

Local Area NetworkRoom / Desk Area NetworkM2M & IoTV2V & V2I
IEEE 802.11ax (Wi-Fi 6 / 6E)
IEEE 802.11ac (Wi-Fi 5)
IEEE 802.11n (Wi-Fi 4)
IEEE 802.11ay
IEEE 802.11aj
IEEE 802.11ad
IEEE 802.11ah
IEEE 802.11af
IEEE 802.11p

In September 1990, an IEEE working group began to work on a standard for wireless networks with 1 Mbit / s in the 2.4 GHz frequency range. This created a protocol and transmission method for wireless networks. The IEEE 802.11 standard was quickly accepted and spread rapidly.
Within a few years, extensions to radio technology emerged, which above all, but not only, increased the transmission rate on the radio interface.

Wi-Fi - Wireless Fidelity / WFA - Wi-Fi Alliance

In connection with IEEE 802.11 and Wireless LAN, the term "Wi-Fi", which stands for "Wireless Fidelity" and is communicated by the Wi-Fi Alliance (WFA), is used very often. The Wi-Fi Alliance (WFA) is a manufacturer association that voluntarily tests WLAN devices for conformity with the IEEE standards and for interoperability. The devices then went through a kind of TÜV. This ensures that the devices work together between different manufacturers. The tested devices are then marked as IEEE 802.11 compatible with the Wi-Fi logo.

WLAN transmission technology

The transmission technology of IEEE 802.11 provides for the uncoordinated, unplanned and spontaneous operation of a WLAN. In practice, it means that anyone can put a WLAN base station into operation without having precise technical knowledge of how it works. This means that the radio systems operated in this way must master techniques and measures for coexistence. Usually CSMA / CA is used for this.

WLAN frequencies and WLAN channels

  • below 1 GHz
  • 2.4 GHz (main frequency range)
  • 5 GHz
  • 6 GHz
  • 60 GHz

Several frequency ranges are available for WLAN. The most used range is 2.4 GHz, the second at 5 GHz. There are other frequency ranges that are often only of regional relevance. Furthermore, the use of the frequency ranges for WLAN according to IEEE 802.11 is regulated very differently in different regions.

WiFi security

Radio signals move in free space. This means that anyone who can receive a radio signal can intercept or manipulate the radio signals sent. It is practically impossible to prevent wiretapping of a radio link. This is why WLANs must be operated with authentication and encryption.
Another sticking point is the use of the WLAN and the use of the Internet connection provided by it by strangers. The operator of an unsecured WLAN can be held legally responsible and therefore liable if people unknown to him misuse his Internet access to violate the law. The regional courts of Hamburg (2006) and Düsseldorf (2008) have ruled on this. There are also contrary judgments. But it is advisable to always have the encryption activated. Preferably with WPA3. Older security procedures such as WEP, WPA and WPA2 should no longer be used. WLAN devices that do not support at least WPA2 should be replaced urgently.

WLAN authentication

Strangers should not be allowed to use your own WLAN. Therefore, access to the WLAN should at least be restricted with a password. The password is then only given to people and devices that are allowed to access the WLAN. But once the password is known, access is unsecured.
In the case of larger WLANs with many users and access points, authentication can also be integrated with the IEEE 802.1x protocol, for which each user needs their own access data (user name and password). Access can easily be released or restricted at a central point.

IEEE 802.11 vs. Bluetooth

During the development of the WLAN standard IEEE 802.11 and Bluetooth, similarities quickly emerged. Both radio standards work in the 2.4 GHz frequency band and are intended to connect different devices to one another via radio. Both standards are characterized by their individual strengths and are therefore available on the market in different devices.
Wireless LAN exceeds Bluetooth in its range and transmission speed and is therefore used in local networks.
With low hardware costs, low power consumption and real-time capability, Bluetooth is better suited for voice transmission, audio-video solutions and ad hoc connections between small devices.

Tasks and exercises with the Raspberry Pi

WLAN technology

WLAN topology

Transmission technology

WiFi security

WLAN extensions

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