Detailed description of WLAN test features and test content (1)

No one is skeptical that WLAN is currently the most popular technology and market in the network industry. However, the monitoring and testing of WLAN is still a problem that is often ignored, people are even using laptops and wireless NICs to test and accept wireless projects. This reminds us of the early Ethernet testing scenarios. The following is a discussion of the basic concepts of wireless testing. In fact, from the perspective of development sources, wireless LAN and Ethernet are the same source. In terms of MAC Layer Protocol features, wireless LAN and wired Ethernet share the same transmission channel, currently, most enterprise applications of Wireless LAN are used to supplement wired networks. Therefore, the test of Wireless LAN has many similarities with that of wired Ethernet.

Features of WLAN

Although the MAC layer protocol of the wireless LAN is different from that of the Ethernet, the Ethernet transmission protocol is (CSMA/CD), and the wireless network standard uses CSMA/CA (with multi-path access with a carrier that avoids conflict) the common feature of MAC mode is that multiple access devices share a communication channel. WLAN actually has a "line". For 802.11b wireless LAN, this line is an 83.5MHz band in the GHz band. In fact, WLAN is much more complex than wired LAN in terms of design, management, and maintenance, and there are more variables that affect network performance, sometimes even unpredictable. The CSMA/CA protocol is indeed inferior to the CSMA/CD Protocol. However, due to the characteristics of wireless transmission, CSMA/CD Protocol cannot be used in the wireless LAN. The channel utilization is affected by the transmission distance and the degree of openness. When the distance is far or there are obstacles, there will be hidden terminal problems, reducing the channel utilization. Specifically, the highest channel utilization rate is related to the transmission rate. In IEEE802.11b Wireless LAN, the maximum channel utilization can reach 90% at 1 Mbps, while the maximum channel utilization is only about 65% at 11 Mbps. However, these shortcomings do not cover up the advantages of Wireless LAN. The first is to get rid of the limitations of the line, which is a turning point for network development. Secondly, because the MAC layer protocol uses the CSMA/CA protocol, it can be seamlessly connected to the standard Ethernet protocol. Although a wireless LAN is somewhat different from a wired LAN and requires an access point (AP) connection, its compatibility makes it easy for a WLAN to work in conjunction with the LAN into a single network. Third, WLAN solves network application problems in areas that are not suitable for cabling or cannot be cabled.