Wi-Fi is a brand of wireless network communication technology, which is owned by the Wi-Fi Alliance. The purpose is to improve the interoperability between wireless network products based on IEEE 802. 1 1 standard.
At present, most people will confuse Wi-Fi with IEEE 802. 1 1. Even equate Wi-Fi with wireless Internet access.
Wi-Fi Alliance was founded in 1999, and its name was WECA. In June 2002, it was officially renamed as Wi-Fi Alliance.
Popular saying:
WIFI is a wireless network technology, which used to connect computers through network cables, but now it is connected to the Internet through radio waves. Wireless router is common, so in the effective range of radio wave coverage of this wireless router, WIFI connection can be used for networking. If a wireless router is connected to an ADSL line or other Internet access line, it is also called a "hotspot".
At present, most of the common wireless routers on the market have a speed of 54M, and the next level is 108M. Of course, this speed is not the speed at which you surf the Internet. The speed of surfing the Internet mainly depends on the Internet lines of WIFI hotspots.
To put it bluntly, it is a wireless local area network. "Wi-Fi" is a wireless local area network based on IEEE 802. 1 1b standard, which is what we usually call WIFI. [Edit this paragraph ]WIFI comes from IEEE 802. 1 1. The first version was published in 1997, which defined the MAC layer and the physical layer. The physical layer defines two wireless FM modes and one infrared transmission mode working in the ISM band of 2.4 GHz, and the total data transmission rate is designed to be 2 Mbit/s. The communication between the two devices can be carried out in a self-organizing way or under the coordination of a base station (BS) or an access point (AP).
Two supplementary versions have been added to 1999: 802. 1 1a defines the physical layer with a data transmission rate of 54Mbit/s in the 5GHz ISM band, and 802. 1 1b defines the data transmission rate as/kloc-0 in the 2.4GHz ISM band.
The ISM band of 2.4GHz is common in most countries in the world, so 802.5438+0 1B has been widely used. Apple named its 802. 1 1 standard airport. 1999, the industry set up a Wi-Fi alliance to solve the production and equipment compatibility problems of products conforming to the 802. 1 1 standard. Wi-Fi is an organization that formulates 802. 1 1 wireless networks, and does not represent wireless networks. [1][2][ Edit this paragraph] Introduction ]WIFI Wi-Fi is commonly known as wireless broadband.
The so-called Wi-Fi is actually another name for IEEE 802.11b. It is an industry term issued by an organization called WECA, which translates into "wireless compatibility certification" in Chinese. It is a short-distance wireless transmission technology, which can support the radio signal of surfing the Internet within hundreds of feet. With the development of technology, IEEE 802. 1 1a and IEEE 802.1g appeared, and the standard IEEE 802. 1 1 has been collectively referred to as Wi-Fi. From the application level, to use Wi-Fi, users must first have a Wi-Fi-compatible client device.
Wi-Fi is a technology that can help users access e-mail, internet and streaming media. It provides users with wireless broadband Internet access. At the same time, whether at home, in the office or on the road, it is also a quick and convenient way to surf the Internet. Places where you can access Wi-Fi networks are called hotspots. Wi-Fi or 802. 1 1b works in the 2.4Ghz band, and the maximum supported rate is 1 1Mbps. 802. 1 1 Space also has two protocols, including (a) and (g). They are also publicly used, but 802.438+0438+0b is the most commonly used in the world.
Wi-Fi hotspots are created by installing an access point on an Internet connection. The access point transmits wireless signals over short distances, usually covering 300 feet. When a Wi-Fi-enabled device (such as Pocket PC) encounters a hotspot, the device can wirelessly connect to the network. Most hot spots are located in places for the public to visit, such as airports, coffee shops, hotels, bookstores and campuses. Many homes and offices also have Wi-Fi networks. Although some hotspots are free, most stable public Wi-Fi networks are provided by private Internet service providers (ISP), so users will be charged a certain fee when connecting to the Internet.
The full name is wireless fidelity. 802. 1 1b is sometimes mislabeled as Wi-Fi. In fact, Wi-Fi is a trademark of WLANA, which only guarantees that the goods using the trademark can cooperate with each other, and has nothing to do with the standard itself. But people are getting used to calling 802.6438+0 1B protocol with WIFI. Its biggest advantage is its fast transmission speed, which can reach 1 1Mbps. In addition, it has a long effective distance and is compatible with various existing 802. 1 1 DSSS devices. Notebook technology-Centrino technology is based on this standard.
IEEE (Institute of Electronic and Electrical Engineers) 802. 1 1b wireless network specification is an extension of IEEE 802. 1 1 network specification, and its maximum bandwidth is12Mbps, which can be adjusted in case of weak signal or interference. Its main features are: high speed and high reliability. In the open area, the communication distance can reach 305 meters, and in the closed area, the communication distance is 76 meters to 122 meters, which is convenient to integrate with the existing wired Ethernet and has lower networking cost.
The official name of Wi-Wi-Wi-Fi(WirelessFidelity) is "IEEE802. 1 1b", which, like Bluetooth, belongs to short-distance wireless technology used in office and home. Although this technology is worse than Bluetooth technology in data security, it is slightly better in the coverage of radio waves. Wi-Fi coverage can reach about 300 feet (about 90 meters), and it goes without saying that offices can also be used in smaller buildings. Therefore, Wi-Fi has always been the preferred technology for enterprises to realize their own wireless LAN. Another reason is that Wi-Fi seems to be better than the expensive 3G enterprise network. The hotspots about Wi-Fi were all born in 2002. In the United States, Wi-Fi, like the early Internet, shows the trend that a single spark can start a prairie fire. In 2003, it is destined to have a bright future in the world.
The high-speed wireless Internet access brought by Wi-Fi will be as common as people using mobile phones today. At present, manufacturers are actively applying this technology to all kinds of devices from handheld computers to desktop computers to create new selling points. As the number of Wi-Fi devices increases, its price will drop. In 2006, the global annual output of Wi-Fi equipment will reach 33 million.
Correct pronunciation
Phonetic transliteration: "waifai"
According to the famous American Webster's University Dictionary and French Robert Dictionary, the phonetic symbol is [wifi] and the pronunciation is still "waifai".
WIFI highlights its advantages.
First, the coverage of radio waves is wide. The coverage of radio waves based on Bluetooth technology is very small, with a radius of only about 50 feet? About 15 meters? And the radius of Wi-Fi can reach about 300 feet? About 100 meter? Needless to say, the office can be used in the whole building. Recently, Vivato Company introduced a new type of switch. It is reported that this product can make the current Wi-Fi wireless network reach 300 feet? Approaching 100 meter? Communication distance expanded to 4 miles? About 6.5 kilometers? .
Secondly, although the wireless communication quality transmitted by Wi-Fi technology is not very good, the data security performance is worse than that of Bluetooth, and the transmission quality needs to be improved, but the transmission speed is very fast, reaching 54mbps, which meets the needs of personal and social informatization.
Third, the threshold for manufacturers to enter this field is relatively low. Manufacturers only need to set up "hot spots" in crowded places such as airports, railway stations, coffee shops and libraries, and access the Internet to these places through high-speed lines. In this way, because the radio waves emitted by "hot spots" can reach the radius of tens of meters to 100 meters from the access point, users can surf the Internet at high speed as long as they enter this area with their laptops or PDA supporting wireless LAN. In other words, manufacturers do not have to spend money on network wiring access, thus saving a lot of costs.
According to the standards used by wireless network cards, the speed of WIFI is different. Among them, the maximum value of IEEE802. 1 1b is1Mbps (some manufacturers have supporting equipment that can reach 22Mbps), IEEE802. 1 1a is 54Mbps, and IEEE 802./kloc.
WIFI is a wireless network composed of AP (access point) and wireless network card. AP is generally called a bridge or access point, as a bridge between traditional wired LAN and wireless LAN. Therefore, any PC equipped with wireless network card can share the resources of wired local area network or even wide area network through AP, and its working principle is equivalent to a HUB with a built-in wireless transmitter or router, while the wireless network card is a client device responsible for receiving signals transmitted by AP.
Wireless b/g indicates the model of network card, which can be divided into 802. 1 1a, 802.1/b, 802.1g according to its speed and technology.
Speaking of wireless networks, everyone has a specious feeling. Is wireless just the interconnection of two computers? Don't! This is the concept of wireless in the last century. The new generation of wireless network will establish people's brand-new feeling of wireless local area network, without wiring and relatively free to use. Demand determines the development of the market. IT is rare to see which IT technology or product has such a rapid growth momentum. It is no longer a dream to surf the internet anytime and anywhere without any constraints. Among them, WiFi plays a vital role. Wi-Fi stands for "wireless fidelity" and refers to a subset of IEEE 802. 11b that is fully compatible with the 802.1standard. It adopts open 2.4GHz direct sequence spread spectrum, and the maximum data transmission rate is 1 12Mbps. The transmission rate can also be adjusted to 5 according to the signal strength. The maximum transmission range of wireless communication is 300 meters outdoors and 100 meters indoors, which is the most used transmission protocol at present. Compared with wired network, it has many advantages:
No wiring is required
The main advantage of WiFi is that it does not need wiring and is not limited by wiring conditions. It is very suitable for the needs of mobile office users and has a broad market prospect. At present, it has expanded from traditional special industries such as medical care, inventory control and management services to more industries, and even started to enter the fields of families and educational institutions.
Safety and health care department
IEEE802. 1 1 stipulates that the transmission power shall not exceed 100 MW, and the actual transmission power is about 60~70 MW. What kind of concept is this? The transmitting power of mobile phones is about 200 MW to 1 watt, and the handheld walkie-talkie is as high as 5 watts. Moreover, the wireless network is not in direct contact with the human body like a mobile phone, so it is absolutely safe. [Edit this paragraph] WIFI construction method Generally speaking, the basic equipment for building a wireless network is the wireless network card and AP, so that network resources can be shared wirelessly with the existing wired architecture, and the installation cost and complexity are much lower than that of the traditional wired network. If it's just a point-to-point network of several computers, you don't need an AP, just equip each computer with a wireless network card. AP is the abbreviation of AccessPoint, which is generally translated as "wireless access node" or "bridge". It mainly acts as a bridge between wireless workstation and wired LAN in MAC of media access control layer. With AP, wireless workstations can connect to the network quickly and conveniently, just like hubs in general wired networks. Especially for the use of broadband, WiFi has more advantages. After the wired broadband network (ADSL, local area network, etc.). ) to the AP, you can install a wireless network card in your computer. It is enough for ordinary families to have an AP. Even after the user's block is authorized, you can surf the Internet in a * * * way without adding a port.
Long-distance work, although the working distance of wireless WIFI is not large, under the condition of complete network construction, the real working distance of 802. 1 1b can reach more than 100 meters, which solves the problems of data error correction and error code when moving at high speed, and well solves the problems of handover and security authentication between WIFI devices and base stations.
However, with the evolution of the wireless industry from 802. 1 1g to the next generation of 802.1n standard, more and more products begin to adopt the powerful 802. 1 1n technology, because it can provide faster and faster. 802. 1 1n is 7 times faster than 802. 1 1g and 3 times faster than Ethernet. In addition, it has a larger coverage and can provide a strong connection in the whole family, even in every corner. 802 438+05438+0N is the first wireless multimedia distribution technology that can simultaneously carry high-definition video, audio and data streams because of its large bandwidth. Moreover, the 802. 1 1n product also provides concurrent dual-frequency operation, so it can provide more channel capacity for broadband multimedia applications.
Nowadays, many consumers have a library of digital movies, TV programs, music and photos, and they are eager to access these media contents from anywhere in the family through wireless devices. 802. 1 1n not only supports multiple concurrent users and devices, but also its super function can ensure the quality of service, ensure that all devices in the family provide a better user experience, and provide intelligent content management and publishing.
802. The version of11n standard is still draft version 2.0, and the approval of the official version is expected to be completed in 2009. 802. The draft version 2.0 of11n specification has been perfected, and there should be no major changes to the draft in the future. For the 802. 1 1n devices that support the early draft of 802.1n, these devices can be upgraded by firmware. In order to promote the popularization of 802. 1 1n, Wi-Fi authentication is very important.
Therefore, the trend of market transition to 802. 1 1n is more and more obvious, and the cost performance is higher. 802. 1 1n ecosystem is also developing rapidly. More and more manufacturers add 802. 1 1n technology to HDTV, set-top boxes and media adapters. This trend will promote the wireless coverage of video distribution in the whole family to become a new killer application. According to ABI research, 802. 1 1n products will account for nearly half of all Wi-Fi deliveries in 2008. [7]