what is the Wifi network
wi-fi for IEEE defines a wireless network communication industry standards (IEEE802.11).Wi-fi in the first version, published in 1997, which defines the media access access control (MAC) layer and the physical layer.The physical layer defines the work on the 2.4 GHz ISM band of two kinds of wireless FM mode and an infrared transmission way, according to the total transmission rate for 2 mbits design.Free to direct communication between the two devices (AD hoc) manner, also can be in the Base Station (Base Station, BS) or Access Point (Access Point, AP) under the coordination of.
wi-fi for IEEE defines a wireless network communication industry standards (IEEE802.11).
wi-fi in the first version, published in 1997, which defines the media access access control (MAC) layer and the physical layer.The physical layer defines the work on the 2.4 GHz ISM band of two kinds of wireless FM mode and an infrared transmission way, according to the total transmission rate is designed for 2 mbit/s.Free to direct communication between the two devices (AD hoc) manner, also can be in the Base Station (Base Station, BS) or Access Point (Access Point, AP) under the coordination of.
1999 plus the added two version: 802.11 a defines a data transfer rate on the 5 GHz ISM frequency band can be up to 54 mbit/s, the physical 802.11 b defines a on the 2.4 GHz ISM band but 11 mbit/s data transfer rate is as high as the physical layer.2.4 GHz ISM frequency band by most countries in the world, so the 802.11 b has been the most widely used.Apple 802.11 standard named AirPort to develop themselves.Industry (1999) established the wi-fi alliance, is committed to solve the 802.11 standard products and equipment compatibility problems.802.11 standard and supplement.
802.11, 1997, the original standard (2 mbit/s work in 2.4 GHz).
802.11 a, 1999, supplement the physical (54 mbit/s work in the 5 GHZ).
802.11 b, 1999, supplement the physical (11 mbit/s work in 2.4 GHz).
802.11 c, in line with the media access control (MAC) Layer of 802.1 D bridge (MAC Layer Bridging).
802.11 d, according to the regulations of national radio do adjustment.
802.11 e, the level of Service (Quality of Service, QS) support.
802.11 f, the connectivity of the base station (Interoperability).
802.11 g, supplement the physical (54 mbit/s work in 2.4 GHz).
802.11 h, wireless coverage radius adjustment, indoor and outdoor (indoor) (is suing) channel (5 GHZ band).
802.11 I, security and authentication (Authentification).
802.11 n, import multiple input/output (MIMO) technology, is basically an extension of the 802.11 a version.IEEE standard
in addition to the above, the other one is called the IEEE802.11 b + technology, through the PBCC technology (Packet Binary Convolutional Code) based on IEEE802.11 b (2.4 GHz band) provides 22 mbit/s data transfer rate.But it in fact is not a public IEEE standard, but a property proprietary technology (property right belongs to the Texas Instruments, Texas Instruments).There are also known as 802.11 g + technology, on the basis of IEEE802.11 g with 108 mbit/s transmission rate, like 802.11 b +, also is a standard technique, by the wireless network chip makers Atheros advocate for SuperG.
a wi-fi connection point network members and structure of the site (Station), the most basic part of the network.
the Basic Service unit (Basic Service Set, BSS).Network is the most basic services unit.The most simple service units can only consist of two sites.Site can dynamically link (associate) into the basic service unit.
Distribution System (Distribution System, the DS).Distribution system is used to connect different basic services unit.Distribution system using the media (Medium) logically and basic services unit using Medium is completely separated, although they may turn out to be the same physical Medium, such as the same radio frequency.
access points (Acess Point, AP).The identity of the access points that have a common site, and have access to the function of the distribution system.
extension Service units (Extended Service Set, ESS).Made from a mix of distribution system and the basic service unit.This combination is logically, not physically, basic services unit of different objects are likely to geographical location.Distribution system can also use a variety of technologies.
mark (Portal), is also a logical component.Used in the wireless LAN and wired LAN or other networks.
there are three kinds of media sites use wireless medium, the distribution system used by the media, and wireless local area network (LAN) and integration with other local area network (LAN) using medium.Physically they may overlap each other.IEEE802.11 only responsible for on site use wireless media Addressing (Addressing).Distribution system and other LAN address does not belong to the scope of the wireless local area network (LAN).
ieee802. 11 no specific definition of distribution system, just define the distribution system should provide services (Service).The wireless local area network (LAN) defines the 9 kinds of services,
5 kinds of service belongs to the task of Distribution system, respectively, the connection (Association), end connection (Diassociation), Distribution (Distribution), the Integration (Integration), join again (Reassociation).
4 service belongs to the mission of the site, respectively, Authentication (Authentication), end Authentication (Deauthentication) and Privacy (Privacy), MAC data transmission (MSDU delivery).