WIFI related brief Full name Wireless Fidelity, also known as 802.11b standard, its biggest advantage is that the transmission speed is higher , can reach 11Mbps, in addition to its effective distance is also very long, but also with a variety of existing 802.11 DSSS equipment is compatible. The most popular laptop technology this summer, Centrino, is based on this standard. Here's more: WIFI speeds vary depending on the standard used by the wireless card. Among them, IEEE802.11b is up to 1 1Mbps (some manufacturers can reach 22Mbps with matching equipment), IEEE802.11a is 54Mbps, and IEEE802. 11g is also 54Mbps. In fact, WIFI should be 802.11, not 802.11b, which now includes: 802.11 , the 1997, the original standard (2Mbit/s operating at 2.4GHz). 802.11a, 1999, physical layer supplement (54Mbit/s operating at 5GHz). 802.11b, 1999, physical layer supplement (11Mbit/s operating at 2.4GHz). 802.11c, 802.1D-compliant Media Access Control Layer (MAC) Bridging. 802.11d, adapted to national radio regulations. 802.11e, Quality of Service (QoS) support. 802.11f, Base Station Interoperability. 802.11g, Physical Layer Supplement (54Mbit/s operating at 2.4GHz). 802.11h, Wireless coverage radius adjustment, indoor and outdoor channels (5GHz band). 802.11i, complementary to security and authentication. 802.11n, which introduces Multiple Input Output (MIMO) technology and is basically an extension of 802.11a. WIFI related brief Full name Wireless Fidelity, also known as 802.11b standard, its biggest advantage is the transmission speed is higher, can reach 11Mbps, in addition to its effective distance is also very long, but also with a variety of existing 802.11 DSSS equipment compatible. This summer's most popular laptop technology, Centrino, is based on this standard. IEEE ([U.S.] Institute of Electrical and Electronics Engineers) 802.11b wireless network specification is a variant of the IEEE 802.11 network specification, the highest bandwidth of 11 Mbps, in the case of weak signals or interference, the bandwidth can be adjusted to 5.5 Mbps, 2 Mbps and 1 Mbps, the bandwidth is automatically adjusted to effectively protect the stability and reliability of the network. Its main characteristics are: fast speed, high reliability, communication distance up to 305 meters in open area and 76 meters to 122 meters in closed area, easy to integrate with existing wired Ethernet network and lower cost of networking. Wi-Fi (Wireless Fidelity) technology is the same as Bluetooth technology. technology, like Bluetooth, is a short-range wireless technology used in offices and homes. The technology uses the frequency band around 2.4 GHz, which is currently an unlicensed wireless band. There are two standards available, IEEE802.11a and IEEE802.11b, which are favored by manufacturers because of their advantages. WIFI highlights the advantages First, the radio wave coverage is wide, based on the Bluetooth technology, the radio wave coverage is very small, the radius is only about 50 feet or so? which is about 15 meters? while Wi-Fi has a radius of up to about 300 feet? about 100 meters. and offices, needless to say, can be used in an entire building. A new switch was recently introduced by Vivato. It is said to be capable of extending the current Wi-Fi wireless network by 300 feet? close to 100 meters? of communication distance to 4 miles? about 6.5 kilometers? Secondly, although the quality of wireless communication transmitted by Wi-Fi technology is not very good, the data security performance is a bit worse than Bluetooth, and the transmission quality needs to be improved, the transmission speed is very fast and can reach 11mbps, which is in line with the needs of personal and social informatization. Third, the threshold for manufacturers to enter the field is relatively low. Manufacturers only need to set up "hotspots" in airports, stations, coffee shops, libraries and other densely populated places, and connect the Internet to these places through high-speed lines. In this way, because the "hot spots" emit radio waves that can reach a radius of tens of meters to 100 meters from the access point, the user can access the Internet at high speed as long as the laptop or PDA that supports wireless LAN is brought to the area. In other words, manufacturers do not have to spend money to carry out network wiring access, thus saving a lot of costs. The speed of WIFI varies depending on the standard used by the wireless LAN card. Among them, IEEE802.11b is up to 11Mbps (some vendors can reach 22Mbps with matching equipment), IEEE802.11a is 54Mbps, and IEEE802.11g is also 54Mbps. WIFI is a wireless network consisting of an AP (Access Point) and a wireless network card, and an AP is generally known as a network AP is generally known as a network bridge or access point, which is used as a bridge between traditional wired local area network and wireless local area network, so any PC equipped with a wireless network card can share the resources of wired local area network or even wide area network through the AP, which is equivalent to the principle of a built-in wireless transmitter of the HUB or routing, and the wireless network card is responsible for receiving the signals emitted from the AP CLIENT end of the device. The wireless card is the CLIENT device responsible for receiving the signals transmitted by the AP. And wireless b/g indicates that the model of the card, according to its speed and technology can be divided into 802.11a, 802.11b, 802.11g Speaking of wireless networks, we have a plausible feeling that wireless is simply two computers are interconnected No! This has been the last century of the wireless concept of a new generation of wireless networks, which will be free of cabling and the use of relatively free, to build people's understanding of wireless LAN. No! This is already the wireless concept of the last century, the new generation of wireless network will be without wiring and the use of relatively free, to establish a new feeling of wireless LAN. Demand determines the development of the market, and it is rare to see any kind of IT technology or product that can have such a rapid growth momentum as it is, without any constraints to access the Internet anytime, anywhere is no longer a dream, in which WiFi plays a crucial role. 802.11 standard IEEE802.11b subset, which uses the open 2.4GHz direct sequence spread spectrum, the maximum data transmission rate of 11Mbps, but also according to the signal strength of the transmission rate can be adjusted to 5.5Mbps, 2Mbps and 1Mbps bandwidth. The transmission range is up to 300 meters outdoors and 100 meters indoors when there are obstacles, and it is the most used transmission protocol nowadays. It has many advantages over wired networks: No wiring required The main advantage of WiFi is that it does not require wiring and can be used without the constraints of wiring conditions, so it is very suitable for the needs of mobile office users and has a broad market outlook. It has already expanded from traditional healthcare, inventory control and management services to more specific industries, and has even begun to enter the home, as well as educational institutions and other areas. Health and Safety IEEE802.11 stipulates that the transmit power must not exceed 100 milliwatts, and the actual transmit power is about 60~70 milliwatts, what kind of concept is this? The transmit power of cell phone is about 200 mW to 1 watt, handheld walkie-talkie as high as 5 watt, and the wireless network is not used in a way like cell phone direct contact with the human body, it should be absolutely safe. WIFI setup method The basic equipment for setting up a wireless network is a wireless network card and an AP, which can share network resources in a wireless mode with the existing wired structure, and the cost and complexity of the setup process are much lower than the traditional wired network. If only a few computers peer-to-peer network, you can not AP, only need to equip each computer with a wireless network card, AP for AccessPoint short, generally translated as "wireless access node", or "bridge". It mainly plays a role in the media access control layer MAC wireless workstations and wired local area network bridge. With an AP, like a general wired network hub, wireless workstations can quickly and easily connect to the network. Especially for the use of broadband, WiFi is more advantageous, wired broadband network (ADSL, cell LAN, etc.) to the home, connected to an AP, and then install a wireless network card in the computer can be. Ordinary families have an AP is already enough, and even the user's neighborhood is authorized, then there is no need to increase the number of ports, but also to **** enjoy the way to the Internet. Long-distance work Don't look at the working distance of wireless WIFI is not big, in the case of complete network construction, 802.11b real working distance can reach more than 100 meters, and solved the problem of error correction of data in high-speed movement, the problem of error code, WIFI equipment and equipment, equipment and base station switching and security authentication have been well resolved. WIFI future development Within these two years, the number of wireless AP is growing rapidly, the convenience and efficiency of the wireless network so that it can be rapidly popularized. In addition to AP in some of the current public **** place, foreign countries have precedents to wireless standards to build a metropolitan area network, therefore, WiFi's wireless status will become increasingly strong. WiFi is currently the mainstream standard for wireless access, but how far will WiFi go? Under the strong support of Intel, WiFi already has a successor. It is fully compatible with the existing WiFi WiMAX, compared to WiFi's 802.11X standard, WiMAX is 802.16x. Compared with the former, WiMAX has a longer transmission distance, a wider choice of frequency bands and higher access speeds, etc., and it is expected to become a mainstream standard for wireless networks in the next few years, and Intel plans to adopt this standard in the future. Intel plans to adopt this standard to build wireless wide-area networks in the future. This is a qualitative change from today's wireless LANs or MANs, and existing equipment will still be supported, protecting every penny of investment. All in all, the demand for mobile connectivity by home and small office network users is the driving force behind the growth of the wireless LAN market. Although so far, developed countries such as the United States and Japan are still the regions with the largest number of WiFi users, with the further popularization of e-commerce and mobile office, inexpensive WiFi will surely become the inevitable choice for those who need to make a network connection at any time. Recently, the industry has been rumored that WIFI has an existential crisis. According to foreign media reports, many companies are still investing huge amount of money in WIFI, but there are almost no profitable enterprises. It is reported that many enterprises went bankrupt because of WIFI, and R Wireless gave up the business not long ago. So is the profitability of WIFI really in crisis? Undeniably, the commercialization of WIFI technology has encountered many difficulties. On the one hand, WIFI technology is subject to its own limitations, such as roaming, security and billing, which have not yet been properly resolved. On the other hand, since the profit model of WIFI is not clear, if WIFI is operated as a single network, the lack of commercial users will make the investment return of network construction relatively low, thus also affecting the enthusiasm of telecom operators. However, from the perspective of WIFI technology positioning, I believe that for telecom operators, WIFI technology is mainly positioned as a supplement to high-speed wired access technology, and will gradually become a supplement to cellular mobile communications in the future. Although the commercialization of WIFI technology has encountered some difficulties at present, it is impossible for this advanced technology to organize all functions of the communication system. It can be said that only the complementary use of various means of access can bring economy, reliability and effectiveness. Thus, it can play an important complementary role to 3G in a specific region and range, WIFI technology and 3G technology will have a broad development prospects.