Wi-Fi technology and application (1)
What is Wi-Fi?
Wi-Fi (Wireless Fidelity) is a technology that can wirelessly connect terminals such as personal computers, handheld devices (such as pads, mobile phones) to each other, and is named by the Wi-Fi Alliance.
Wi-Fi was originally the abbreviation of wireless fidelity, which refers to “wireless compatibility certification” in the category of wireless local area networks, which is essentially a commercial certification and a wireless networking technology.
In the past, computers were connected through network cables, but now they are connected through radio waves. A common one is a wireless router, and Wi-Fi connection can be used for networking within the effective range of the wireless router’s radio wave coverage.
What is the difference between WI-FI and WLAN?
The full name of WLAN: Wireless Local Area Networks, refers to the application of wireless communication technology to interconnect computer equipment to form a network system that can communicate with each other and realize resource sharing. WiFi is a technology that allows electronic devices to connect to a wireless local area network (WLAN). WLAN is a big network, and WiFi is a technology under this big network.
WI-FI Protocol and Evolution
| Time | Communication Protocol | Description | ||
| 1999 | 802.11a | 5GHz | 20MHz | 54Mbps |
| 1999 | 802.11b | 2.4GHz | 20MHz | 11Mbps |
| 2003 | 802.11g | 2.4GHz | 20MHz | 54Mbps |
| 2009 | 802.11n | 2.4/5GHz | 20/40MHz | 300/450/600Mbps |
| 2012 | 802.11ac | 5GHz | 40/80MHz | 1200Mbps |
| 2019 | 802.11ax | 6GHz | 160MHz | 1800Mbps |
insufficient:
signal interference:
In real life, many devices we use or some items in our home will interfere with the WIFI signal. For example, microwave ovens, refrigerators, wireless mice, etc. with the same wireless frequency will have an impact. In addition, TVs, refrigerators, metals, water, blue equipment, tiles, etc. will also have a great impact.
Signal attenuation:
When the wireless signal propagates, it will encounter obstacles such as buildings and walls, which will attenuate the signal, and the performance will decrease rapidly with the increase of obstacles and transmission distance.
safety:
In essence, radio waves do not require the establishment of a physical link channel, and wireless signals are scattered. Therefore, it is easy to be monitored, resulting in information leakage.
In the next chapter, we will introduce the speed and signal of WIFI
