Wireless LAN:

Wireless Local Area Networks (无线局域网络) is a very convenient data transmission system. It uses Radio Frequency (RF,射频) technology to replace the local area network composed of the old Coaxial (双铜绞线), which makes wireless The local area network can use a simple access structure to allow users to achieve the ideal state of "portable information and convenient access to the world" through it.

Why use a wireless local area network

For one of the main tasks of local area network management, the time-consuming work of laying cables or checking whether the cables are disconnected is easy to be annoying, and it is not easy to find out where the disconnection is in a short time. Furthermore, due to the continuous update and development of the enterprise and application environment, the original enterprise network must be reconfigured, and the network line needs to be re-installed. Although the cable itself is not expensive, the cost of hiring a technician for wiring is very high. Especially in old buildings, the cost of wiring works is even higher. Therefore, setting up a wireless local area network becomes the best solution.

What Situations Need a Wireless Local Area Network       WLAN onclick=gotoRef(this)>[1] The network is by no means used to replace the wired local area network, but to make up for the insufficiency of the wired local area network to achieve the purpose of network extension. The following situations may require a wireless local area network.

◆ Users without a fixed workplace

◆ Wired LAN is limited by the environment

◆ As backup system for wired local area network

Wireless local area network access technology

At present, when manufacturers design wireless local area network products, there are quite a variety of access design methods, which can be roughly divided into three categories: Narrowband Microwave(窄频微波) technology, Spread Spectrum(展频) technology, and Infrared(红外线) technology , each technology has its advantages and disadvantages, limitations, and comparisons, followed by a detailed discussion of these technical methods.

Technical requirements Since the wireless local area network needs to support high-speed and burst data services, it is also necessary to solve problems such as multipath fading and crosstalk between sub-networks when used indoors. Specifically, a wireless LAN must implement the following technical requirements:

(1) Reliability: The system packet loss rate of the wireless LAN should be lower than 10-5, and the bit error rate should be lower than 10-8.

(2) Compatibility: For the wireless local area network used indoors, it should be as compatible as possible with the existing wired local area network in the network operating system and network software.

(3) Data rate: In order to meet the needs of local area network traffic, the data transmission rate of wireless local area network should be at least 1Mbps or more.

(4) Communication confidentiality: Since data is transmitted in the air through wireless media, WLAN must take effective measures at different levels to improve communication confidentiality and data security performance.

(5) Mobility: support full mobile network or semi-mobile network.

(6) Energy-saving management: When there is no data transmission and reception, the station machine is put into a dormant state, and it is activated when there is data transmission and reception, so as to achieve the purpose of saving power consumption.

(7) Miniaturization and low price: This is the key to the popularization of wireless local area networks.

(8) Electromagnetic environment: WLAN should consider the influence of electromagnetic on human body and surrounding environment.