【Computer Network Basics】Wireless Communication of Data Link
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Wireless communication usually uses electromagnetic waves, infrared rays, lasers, etc. to transmit data. Generally, a higher-speed connection formed within the LAN of the office is called a wireless LAN
Unlimited communication does not require network cables or other visible cables. Therefore, early wireless communication was mainly used for lightweight mobile devices. However, with the continuous improvement of wireless communication speed and the advantages of wireless communication itself that can reduce wiring costs, it will soon be widely used in environments such as offices, homes, shops, stations and airports.
1. Types of wireless communication
In wireless communication, the communication distance can be divided into the following types.
The IEEE802 committee designated
- Wireless PAN
- Wireless LAN
- Wireless MAN
- Wireless Ran
WI-FI
WI-FI is a brand name created by WECA (Wireless Etherent Compatability Alliance) to popularize various standards of IEEE802.11.
WECA has been renamed WI-FI Appliance since October 2002 The organization provides WI-FI equipment manufacturers with interoperability testing of IEEE802,11 products, and issues Wi-Fi Certified certification to qualified products. Therefore, a wireless LAN device with the Wi-Fi logo means that the product has been tested for interoperability and passed certification
. It is similar to the word Hi-Fi (Hight Fidenity high fidelity, high reproducibility) in the audio. Wi-Fi (wireless Fidelity ) Refers to high-quality wireless LAN
2. Precautions when using wireless LAN
Wireless LAN allows users to move their positions freely, place devices freely, and achieve a wide range of communications through radio waves. This also means that within its communication range, anyone can use the wireless LAN, so there is a risk of being in court or tampering.
In the wireless Lan standard, in order to prevent eavesdropping or tampering, it has been defined that data can be transmitted However, for certain standards and standards, decoding tools are scattered everywhere on the Internet, which has exposed their weaknesses. In addition to data encryption, access control should be performed on devices using wireless LAN, which is conducive to building a more secure Network environment
In addition, wireless LAN can use specific frequency bands without a license, so the radio waves of wireless LAN may be interfered by other communication devices, causing signal instability.
For example:
using a 2.4GHz bandwidth 802.11b/g device near a microwave oven requires attention. The radio waves radiated by the microwave oven are close to the frequency of the equipment, and the interference generated may significantly reduce the transmission capacity of the equipment
3.Bluetooth
Similar to IEEE802.11b/g, Bluetooth is a standard that uses 2.4GHz frequency radio waves. The data transmission rate can reach 3Mbps in V2 (actually the maximum throughput is 2.1Mbps). According to the strength of the radio wave signal, the communication distance has three types: 1m, 10m, and 100m. The communication terminal allows up to 8 devices.
If IEEE802.11 is a standard for larger computer devices such as laptops, then Bluetooth is a standard designed for smaller devices such as mobile phones or smart phones, keyboards, and mice.
IEEE standardizes WPAN in its IEEE802.15 specification.
4. WiMAX
WiMAX is a way to use Weibo to realize wireless communication in enterprises or homes. Like DSL or FTTH, it is a way to realize the key steps of wireless network
WiMAX is a wireless MAN and supports wireless communication within the metropolitan area network. Standardized by IEEE802.16, in addition, mobile terminals are standardized by IEEE802.16e.
WiMAX is named by WiMAX Forun (WiMAX Forum). The forum also checks compatibility and service connectivity between manufacturers’ devices
5.ZigBee
ZigBee is mainly used in the remote control of home appliances. It is a short-distance, low-power wireless communication technology. It allows up to 65536 terminals to communicate with each other. The transmission speed of ZigBee varies with the frequency used.