What's the 802.11 standard?

IEEE 802.11 is an IEEE originally developed wireless LAN standard, mainly used to solve the office LAN and campus network, user and user terminals wireless access, the business is mainly limited to data access, the highest rate can reach only 2Mbps. Since 802.11 can not meet the needs of people in both speed and transmission distance, the IEEE group has introduced the 802.11B and 802.11a two new standards successively. The main technical difference between the three is the Mac and the physical layer.

Although some people confuse Wi-Fi with 802.11, but the two are not the same. (see IEEE 802.11b below)

History

Since the Second World War, wireless communications have been valued for their military applications, and wireless communications have been developing, but lack of a wide range of communication standards. As a result, IEEE developed the first version of the standard ──IEEE 802.11 for wireless LANs in 1997. The Media access control layer (MAC layer) and the physical layer are defined. The physical layer defines two frequencies of frequency modulation and an infrared transmission in the 2.4GHz ISM band, and the total data transmission rate is designed as 2mbit/s. Communication between the two devices can be done in a device to device (ad hoc) manner, or in coordination with the base station (base station, BS) or access point (Access Point,ap). In order to obtain good communication quality in different communication environment, the hardware communication mode of CSMA/CA (Carrier Sense Multi access/collision) is adopted.

In 1999, two additional versions were added: 802.11A defines a physical layer with a data transfer rate of up to 54mbit/s on the 5GHz ISM band, 802.11B defines a physical layer on the 2.4GHz ISM band but with a data transfer rate up to 11mbit/s. The 2.4GHz ISM Band is universal for most countries in the world, so 802.11b is the most widely used. Apple called Airport the 802.11 standard it developed. In 1999, the industry established a Wi-Fi Alliance to address the production and equipment compatibility issues of 802.11 compliant products. 802.11 standards and supplements.

IEEE 802.11, 1997, original Standard (2mbit/s, work at 2.4GHz).

IEEE 802.11a,1999, physical layer supplements (54mbit/s, work at the 5GHz).

IEEE 802.11b,1999, physical layer supplements (11mbit/s work at the 2.4GHz). It is also sometimes mistaken for Wi-Fi. In fact, Wi-Fi is a trademark of the Wi-Fi Alliance, which only guarantees that the goods using the trademark can cooperate with one another, and that the standard itself does not actually matter.

IEEE 802.11c, 802.1D-compliant media access control layer bridging (MAC Layer bridging).

IEEE 802.11d, according to the national Radio Regulations made by the adjustment.

IEEE 802.11e, support for service levels (Quality of services, QoS).

IEEE 802.11f, Base Station interconnect (Iapp,inter-access point Protocol), approved by IEEE in February 2006.

IEEE 802.11g,2003, physical layer supplements (54mbit/s, work at the 2.4GHz).

IEEE 802.11h,2004 Year, wireless coverage radius adjustment, indoor (indoor) and outdoor (outdoor) channel (5GHz band).

IEEE 802.11i,2004 years, wireless network security supplements.

IEEE 802.11j,2004 year, according to the Japanese regulations to do the upgrade.

IEEE 802.11l, reserved and ready to be used.

IEEE 802.11m, maintenance standards, mutexes and limits.

IEEE 802.11n, higher transmission rate improvements, support for multiple-input multiple-output technology (Multi-Input Multi-output,mimo).

IEEE 802.11k, the Protocol specification prescribes the wireless local area network spectrum Measurement specification. The formulation of this specification embodies the demand of the wireless local area network for the intelligent use of spectrum resources.

IEEE 802.11p, this communication protocol is mainly used in the wireless communication of vehicle electronic. It is set up to extend from IEEE 802.11来 to meet the relevant applications of intelligent transport systems (Intelligent transportation systems,its).

In addition to the above IEEE standards, there is also a technology called IEEE 802.11b+ that provides convolutional on the basis of the IEEE 802.11b (2.4GHz Band) based on PBCC technology (Packet Binary 22mbit/Code) Data transfer rate of S. But this is in fact not an IEEE open standard, but a proprietary technology, property belongs to Texas Instruments.