IEEE 802.11
The 1990 IEEE 802 Standardization Committee established the IEEE 802.11 Wireless LAN Standard Working Group. This standard defines the physical layer and the Media Access Control (MAC) specification. The physical layer defines the signal characteristics and modulation of the data transmission, and works at 2.4000 to 2.4835GHz band. IEEE 802.11 is a wireless local area network standard initially developed by IEEE, mainly for wireless access to computers in an environment or moving environment that is difficult to wiring, because the transfer rate can only reach 2Mbps, so the business is mainly used for data access.
IEEE 802.11A
In 1999, IEEE 802.11a standard was formulated, the standard specified that the wireless local area network operating band was 5.15 ~ 5.825GHz, the data transmission rate reached 54 Mbps / 72Mbps (Turbo), and the transmission distance was controlled at 10 to 100 meters. 802.11A uses unique spread spectrum technology of orthogonal frequency division multiplexing (OFDM); 25Mbps wireless ATM interface and 10Mbps Ethernet wireless frame structure interface, as well as TDD / TDMA air interfaces; support voice, data, image service A sector can be accessed into multiple users, each with a plurality of user terminals.
IEEE 802.11b
September 1999 IEEE 802.11 is officially approved, the standard specifies that the wireless LAN operating frequency band is 2.4 to 2.4835GHz, and the data transfer rate reaches 11Mbps. This standard is a supplement to IEEE 802.11, using the point-to-peer mode and basic mode, and automatically switches between 11Mbps, 5.5Mbps, 2Mbps, 1Mbps according to the actual situation in terms of data transmission rate, and in 2 Mbps, The 1Mbps rate is compatible with 802.11. 802.11b uses direct sequence DSSS as an agreement. 802.11b is not compatible with 802.11A standards on 5GHz frequencies. Due to low price, 802.11b products have been widely put into the market and operate in many actual workplace.
IEEE 802.11e / f / h
IEEE 802.11E standards improved wireless LAN MAC layer protocol to support multimedia transmission to support all service quality of all wireless LAN wireless broadcast interfaces to ensure QoS mechanisms. IEEE 802.11f, defines communication between access nodes, supports IEEE 802.11 Access Point Interoperable Protocol (IAPP). IEEE 802.11h is used for spectrum management technology of 802.11a.
IEEE 802.11g
The 802.11g standard of IEEE is a speed of popular 802.11b (i.e., Wi-Fi standard) (raised from 11Mb / s from 802.11 to 54Mb / s). 802.11g Access point supports 802.11b and 802.11g of customer equipment. Similarly, the laptop with 802.11g NIC can also access the existing 802.11b access point and the new 802.11g access point. However, the products based on 802.11g standards are still unparalleled. If you need a high speed, the 802.11a product that has been introduced can provide 54MB / s up to the highest speed. The main disadvantage of 802.11a is that the 802.11b device is interoperable, and the 802.11a network card is 50% compared to 802.11b, and the access point is 35%.
IEEE 802.11i
IEEE 802.11i standard is to combine user port authentication and device authentication in IEEE 802.1x, modify and integrate wireless LAN MAC layers, define strict encryption formats and authentication mechanisms to improve the security of wireless LAN. IEEE 802.11i new revision standards mainly include two contents: "Wi-Fi Protection Access" (WPA) Technology and "Strong Security Network". The Wi-Fi Alliance plans to use 802.11i standard as a second version of WPA and began in early 2004. Reference
IEEE 802.16
This standard is primarily applied to broadband wireless access. 802.16 The goal of the working group is to develop standards for fixed broadband wireless access systems, which mainly solve the last mile local loop issue. 802.16 Unlike 802.11a, it is to provide a service quality problem related to sound, video, and data from the beginning to provide a standard that supports truly wireless networks.
IEEE 802.16A
In order to provide a standard for local wireless loop WLL, the IEEE 802 Committee established the 802.16 working group in 1999 to develop broadband wireless standards. IEEE 802.16 is responsible for the establishment of wireless interfaces and related functions of wireless local loops, which consists of three small working groups. Each small working group is responsible for different aspects: IEEE 802.16.1 is responsible for the formulation of 10g to 60G Hertz Wireless interface standard; IEEE 802.16.2 is responsible for developing standards in broadband wireless access system; IEEE 802.16.3 is responsible for the development of wireless interface criteria for obtaining frequency using licensing applications between 2G to 10G Hz. IEEE passed the 802.16A standard specification that supported the WLAN (WMAN) on January 29, 2003, with a frequency range between 2 to 11 GHz. The 802.16a standard specification clearly defines three wireless data transmission mode: the first is single carrier access, which is part of the network for special needs; the second is OFDM (orthogonal frequency division) via 256 carriers (orthogonal frequency division Reuse) Acquisition, specifically provided to most applications; the last is to use a special OFDMA standard using 2048 carriers, using a multi-point transfer application with selective multi-point transmission applications, advanced multi-purpose transmission of stepped network technology. Summary 802.11b and 802.11a proposed a milestone for WLAN development, which are defined in 2.4GHz and 5GHz, and the maximum data rate of 802.11b is 11Mbps, while 802.11a can achieve amazing 54Mbps, such a rate for The wireless network is undoubtedly quite attractive. Although 802.11a has a significant rate advantage, the cost problem has become a stumbling block to restrict its development, so it is currently a lower price, more 802.11b.
Wireless Standard 802.11b 802.11a 802.11g Working Frequency Section 2.4GHz 5GHz 2.4GHz Maximum Data Rate 11MBPS 54Mbps 54MBPS Modulation Technology DSSS / CCK OFDM OFDM coverage is larger
