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What are the standards of WLAN?

Wireless Local Area Network (WLAN) is the latest and most popular LAN technology. The main difference between wireless LAN and wired LAN is that in addition to different transmission media, its media access mode is also different. Wireless LAN adopts 802.11 series standard specifications, and currently there are four main standards.

802. 11b standard: The earliest wireless networking standard, with a transmission speed of 11 Mbps, uses CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) media access technology.
802. 11a standard: 802 11b, the connection speed can reach 54Mbps. However, it is not compatible with 802. 11b standard.
802.11g standard: new physical layer standard, connection speed up to 54Mbps, compatible with 802 11b。
802. 11z standard: It is a standard specially designed to strengthen the security of WLAN. Because of the "wireless" characteristics of WLAN, any user who enters the network coverage area can easily enter the network as a temporary user, which brings great insecurity to the network. For this purpose, 802 The llz standard is dedicated to wireless network Website construction In terms of security, it has made clear provisions, strengthened the user identity authentication system, and encrypted the transmitted data.

CSMA/CA protocol for wireless networks

CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) protocol, namely carrier sense, multiple access/collision avoidance protocol, is defined in IEEE 802 11 standard, applied to wireless LAN. Different from the principle of CSMA/CD (carrier sensing, multiple access/conflict detection), CSMA/CA uses ACK signal to avoid conflicts in WLAN communication control. Only when the sender receives the ACK signal returned from the network, can it confirm that the sent data has been sent to the destination correctly; The CSMA/CD mechanism in wired LAN is to detect conflicts, but it cannot be avoided.

CSMA/CA working principle:

Conflict avoidance requires that each sending station listen to the channel before sending data frames. If the channel is idle, it can send data frames.
After sending a data core, the sending station must wait for a short time interval to check the ACK of the acknowledgement packet sent back by the receiving station. If the acknowledgement packet is received, it indicates that there is no conflict in this transmission and the transmission is successful.
If no ACK is received within the specified time, it indicates that there is a conflict and the transmission fails. "You need to resend the data frame until the transmission succeeds within the specified maximum number of retransmissions.".

What are the standards of WLAN

Date：2015-07-15 Source: Shangpin China Type: website encyclopedia
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