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(Summary description)Definition: defines a series of standards for wireless local area network technology. Developed by the Institute of Electrical and Electronics Engineers (IEEE), this standard includes 802.11a, 802.11b, and the emerging 802.11g. The 802.11h and 802.11i standards are still in development at the time of this publication.


(Summary description)Definition: defines a series of standards for wireless local area network technology. Developed by the Institute of Electrical and Electronics Engineers (IEEE), this standard includes 802.11a, 802.11b, and the emerging 802.11g. The 802.11h and 802.11i standards are still in development at the time of this publication.

  • Categories:Knowledge
  • Author:
  • Origin:
  • Time of issue:2019-01-29 14:40
  • Views:

Definition: defines a series of standards for wireless local area network technology. Developed by the Institute of Electrical and Electronics Engineers (IEEE), this standard includes 802.11a, 802.11b, and the emerging 802.11g. The 802.11h and 802.11i standards are still in development at the time of this publication.

802.11 is an industry standard for wireless network communication defined by IEEE in 1997 for Wireless LAN (无线局域网络). Since then, this standard has been continuously supplemented and improved to form the 802.11x standard series. The 802.11x standard is the mainstream standard for wireless local area networks and the technical foundation of Wi-Fi. At present, there are mainly two standards in the WLAN field: the IEEE 802.11x series and the HiperLAN/x (European wireless local area network) series.


Among the following standards, 802.11a/b/g should be the most commonly used three standards, which have been widely used; As of May 2006, the standard has not been adopted.



802.11 is a wireless local area network standard originally formulated by IEEE. It is mainly used to solve the wireless access of users and user terminals in office local area networks and campus networks. The business is mainly limited to data access, and the maximum rate can only reach 2Mbps. Since it cannot meet people's needs in terms of speed and transmission distance, the IEEE group has successively launched two new standards, 802.11b and 802.11a. The former has become the current mainstream standard, while the latter is also favored by many manufacturers.



The 802.11a (Wi-Fi5) standard is the successor to the widely used 802.11b standard. It works in the 5GHz U-NII frequency band, the physical layer rate can reach 54Mbps, and the transport layer can reach 25Mbps. It can provide 25Mbps wireless ATM interface and 10Mbps Ethernet wireless frame structure interface, as well as TDD/TDMA air interface; support voice, data, and image services; one sector can access multiple users, and each user can carry multiple user terminal.


802.11b is Wi-Fi, which uses the 2.4GHz frequency band, and the 2.4GHz IXXXXXX frequency band is common to most countries in the world, so 802.11b has been the most widely used. Its maximum data transfer rate is 11Mb/s, without straight line propagation. During dynamic transrating, the data rate can be reduced to 5.5Mb/s, 2Mb/s, and 1Mb/s if the radio conditions deteriorate. The supported range is 300 meters outdoors and up to 100 meters in an office environment. 802.11b uses a connection protocol and packet acknowledgment similar to Ethernet to provide reliable data transfer and efficient use of network bandwidth.


802.11c expands on the medium access control/link connection control (MAC/LLC) level, aiming to formulate a standard for wireless bridging operation, but later the standard was added to the existing 802.1 to become 802.1d.


Like 802.11c, it expands on the media access control/link connection control (MAC/LLC) level, corresponding to the 802.11b standard, and solves the problem of use in countries that cannot use the 2.4GHz frequency band.


802.11e is a WLAN standard formulated by IEEE to meet the requirements of quality of service (QoS). In the transmission of some voice, video, etc., QoS is a very important indicator. In the 802.11MAC layer, 802.11e adds the QoS function. Its distributed control mode can provide stable and reasonable service quality, while the centralized control mode can flexibly support a variety of service quality policies, so that audio and video transmission can be timely, quantitative, and ensure multimedia quality. Smooth application, WIFI Alliance calls this WMM (wi-fi multimedia).


802.11f adds the IAPP (inter-access point protocol) protocol to ensure that the client roams between different access points, allowing the client to switch access areas smoothly and invisible. The 802.11f standard defines the login of access points within the same network and the exchange of information when a user switches from one access point to another.



802.11g is a standard developed to improve a higher transmission rate. It uses the 2.4GHz frequency band and uses CCK technology to be backward compatible with 802.11b (Wi-Fi). At the same time, it supports data up to 54Mbit/s by using OFDM technology. stream, which provides 1.5 times the bandwidth of 802.11a. From 802.11b to 802.11g, we can find the track of the continuous development of WLAN standards: 802.11b is the cornerstone of the evolution of all WLAN standards, and many systems in the future need to be backward compatible with 802.11b. It is not backward compatible with 802.11b, but uses OFDM technology to support data streams up to 54Mbit/s, providing several times the high-speed channels of 802.11b/g, such as 802.11b/g providing 3 non-overlapping channels up to 8-12 indivual;

It can be seen that there is a gap in compatibility with Wi-Fi between 802.11g and 802.11a. Therefore, a dual-band technology to bridge this gap has emerged - dual-band 802.11a+g (= b), it integrates 802.11a/g technology well, works in 2.4GHz and 5GHz frequency bands, complies with 802.11b/g/a and other standards, and is backward compatible with 802.11b, allowing users to simply connect to existing or The 802.11 network of the future is possible.


It is a revised standard to coordinate with Europe's HiperLAN2. There are differences in the planning and application of the 5GHz frequency band in the United States and Europe. The purpose of this standard is to reduce interference to radars in the same 5GHz frequency band. Similar to 802.16 (WIMAX), 802.16B is formulated for coordination with Wireless HUMAN.

802.11h involves two technologies, one is Dynamic Frequency Selection (DFS), where the access point constantly scans the channel for radar, and the access point and associated base stations change frequencies at any time to minimize interference and distribute WLANs evenly traffic; another technique is Transmit Power Control (TPC), which reduces the total transmit power or interference by 3dB.


802.11i is an important standard for wireless local area networks, also known as Wi-Fi Protected Access, which is an access and transmission security mechanism. Equivalent Privacy) WPA (WI-FI Protected Access) with higher protection, so 802.11i is also called WPA2.

WPA uses the Key Integration Protocol at the time for encryption, the algorithm is the same as WEP, but the method of creating the key is different.


It is a customized standard to adapt to Japan's different applications above 5GHz. Japan starts to use 4.9GHz. At the same time, their power is also different. For example, in the same frequency band of 5.15-5.25GHz, Europe allows 200MW of power, while Japan only allows 200MW of power. 160MW.


802.11k provides standards for how wireless local area networks should perform channel selection, roaming services, and transmit power control. It provides wireless resource management, so that the frequency band (BAND), channel (CHANNEL), carrier (CARRIER), etc. can be adjusted and scheduled more flexibly and dynamically, so that the overall utilization efficiency of the limited frequency band can be improved.

Within a wireless LAN, each device is usually connected to the access point that provides the strongest signal. This management can sometimes lead to excessive demand on one access point and lower utilization of other access points, resulting in lower performance of the entire network, which is mainly determined by the number and geographic location of the access users. In an 802.11k compliant network, if the access point with the strongest signal is loaded at its maximum capacity and a wireless device connects to a less utilized access point, in this case even its signal It may be relatively weak, but the overall throughput is still relatively large, because network resources are more effectively used at this time.



Since the word (11L) is easy to be confused with (11i) of the safety specification, and is very similar to (111), it was abandoned for listing.


802.11m is mainly to maintain, amend, improve, and provide explanatory documents for the 802.11 family specification. The m in 802.11m stands for Maintenance.


Improve the transfer speed, the target exceeds 100MBPS. The IEEE802.11n working group was developed from the high-throughput research group, and plans to increase the transmission rate of WLAN from 54Mbps of 802.11a and 802.11g to more than 108Mbps, and the maximum rate can reach 320Mbps, becoming 802.11b, 802.11a, 802.11g Another important criterion after that. Different from the previous 802.11 standard, the 802.11n protocol is a dual-band working mode (including two working frequency bands of 2.4GHz and 5.8GHz), which ensures compatibility with the previous 802.11a/b/g standard.


Formulated for VOWLAN (Voice over WLAN), faster unlimited handover, and read voice (voice) has higher transmission priority than data (Data).


80211p is a standard released for the special environment of automotive communication. The initial setting is to have a transmission speed of 6MBPS within a distance of 300M. It works in the 5.9GHz frequency band and has a transmission distance of 1000 feet and a data rate of 6Mbps. 802.11p will be able to be used in many aspects such as toll station payment, automobile safety business, e-commerce through automobiles, etc.

From a technical point of view, 802.11p has carried out a number of improvements to 802.11 for special environments such as automobiles, such as more advanced switching between hotspots, more support for mobile environments, enhanced security, and enhanced identity authentication.



Develop a mechanism to support VLAN (virtual LAN, virtual local area network).


The 802.11r standard is aimed at reducing the time required for authentication while roaming, which will help support real-time applications such as voice.

Mobile users using wireless telephony must be able to quickly disconnect from one access point and reconnect to another. The delay time in this switching process should not exceed 50 milliseconds, because this is the time interval that the human ear can perceive. However, the average delay of 802.11 network roaming is several hundreds of milliseconds, which directly leads to interruptions in the transmission process, resulting in connection loss and voice quality degradation. So for the widely used 802.11-based wireless voice communication, faster handover is critical.

802.11r improves the handoff process for mobile client devices as they move between access points. The protocol allows a wireless client to establish a secure and QoS-enabled state with the new access point before a handover occurs, which minimizes connection loss and call interruptions.


Formulate and implement the most advanced MESH network, providing capabilities such as self-configuring and self-healing. A wireless mesh network can connect multiple wireless local area networks together to cover a college campus or an entire city. When a new access point is added, it can automate security and quality of service settings. Packets across the mesh automatically avoid busy access points and find the best route. There are currently 15 proposals for this standard. The IEEE may officially endorse the standard in 2008.


Provides a standard for a consistent methodology to improve the evaluation and measurement of radio link characteristics to measure wireless network performance.


Interactivity with other networks. In the future, more products will have both Wi-Fi and other wireless protocols, such as GXXXXXX, Edge, EV-DO, etc. The working group is developing methods for transferring information between different networks to simplify network switching and roaming.


Wireless network management. Working Group V is the latest group to be formed, and its mission will be based on the results achieved by 802.11k. 802.11v is primarily aimed at operators, dedicated to enhancing the services provided by Wi-Fi networks.


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