What is wi-fi)

What is wi-fi)

The IEEE 802.11b wireless network specification is a variant of the IEEE 802.11 Network specification. The maximum bandwidth is 11 Mbps. when the signal is weak or there is interference, the bandwidth can be adjusted to 5.5 Mbps, 2 Mbps, and 1 Mbps. The bandwidth is automatically adjusted to effectively ensure the stability and reliability of the network. Its main features are: fast speed and high reliability. in the open area, the communication distance can reach 305 meters. in the Closed Area, the communication distance is 76 meters to 122 meters, it facilitates the integration with existing wired Ethernet networks, reducing the cost of networking.

Wi-Fi-fiwirelessfidelity, similar to Bluetooth, is a short-distance wireless technology used in offices and homes. This technology uses a 2-4 GHz band, which is currently not licensed as a wireless band. Currently, two standards are available: IEEE802.11a and IEEE802.11b. This technology has its own advantages, so it is favored by manufacturers.

Wi-Fi technology has the following advantages:

First, radio waves cover a wide range. Bluetooth-based radio waves cover a very small area with a radius of about 50 feet or about 15 meters, the Wi-Fi radius can reach about 300 feet or about 100 meters. Needless to say, the Office can also be used in the whole building. A new vswitch launched by vivato recently. It is reported that this product can extend the current Wi-Fi wireless network distance of 300 feet close to 100 meters to 4 English Rio 6.5 kilometers.

Second, although the wireless communication quality transmitted by Wi-Fi technology is not very good, the data security performance is worse than Bluetooth, and the transmission quality needs to be improved, but the transmission speed is very fast, it can reach 11 Mbps, meeting personal and social informatization needs.

Third, vendors have a low entry threshold. Manufacturers only need to set up "hot spots" in areas with intensive personnel such as airports, stations, coffee shops and libraries, and connect the Internet to the above sites through express lines. In this way, because the electric waves emitted by "hot spots" can reach a distance from the Access Point radius of dozens of meters to 100 meters, users only need to take the laptop or PDA that Supports Wireless LAN to the area, you can access the Internet at high speed. That is to say, manufacturers do not have to spend money to connect to the network wiring, thus saving a lot of costs.

The speed of Wi-Fi varies according to the standard used by the wireless network adapter. The maximum value of IEEE802.11b is 11 Mbps (some manufacturers can reach 22 Mbps in the case of Device Support), IEEE802.11a is 54 Mbps, and ieee802.11g is also 54 Mbps.

Wi-Fi is a wireless network composed of an AP (Access Point) and a wireless network card. AP is generally called a Network Bridge or access point. It serves as a bridge between a traditional wired local network and a wireless local network, therefore, any PC with a wireless network card can share resources in a wired local area network or even a wide area network through an AP. The working principle is equivalent to a hub or a route with a built-in wireless transmitter, the wireless network adapter is the client device responsible for receiving signals sent by the AP.

Wireless B/G indicates the model of the network card. The new and old speed and technology can be divided into 802.11a, 802.11b, and 802.11g.

When talking about wireless networks, we all have a similar feeling: Is wireless simply connecting two computers? No! This is already the concept of wireless networks in the last century. The new generation of wireless networks will create a new sense of Wireless LAN without having to connect and use them freely. Demand determines the development of the market. It is seldom seen that IT technologies or products have such rapid growth momentum as it does. Access to the internet anytime, anywhere is no longer a dream, wiFi plays a vital role. Wi-Fi stands for "wireless fidelity", which is a fully compatible 802.11 standard IEEE802.11b subset. It uses open 2-4 GHz direct sequence spread spectrum, and the maximum data transmission rate is 11 Mbps, you can also adjust the transmission rate to 5.5 Mbps, 2 Mbps, and 1 Mbps Based on the signal strength. No linear transmission is required. The maximum outdoor transmission range is 300 meters, and the maximum indoor transmission range is 100 meters if obstacles exist. This is the most widely used transmission protocol. It has many advantages over wired networks:

1. No wiring required
The main advantage of wifi is that it does not require wiring and is not restricted by wiring conditions. Therefore, it is very suitable for mobile office users and has broad market prospects. At present, it has expanded from traditional special industries such as health care, inventory control and management services to more industries, and even started to enter the fields of families and educational institutions.

2. Health and Security
The emission power stipulated in 100 cannot exceed MW, and the actual emission power is about 60 ~ 70 mW. What kind of concept is this? The transmit power of the mobile phone is about 200 to 1 W, and the handheld walkie talkie is as high as 5 W. In addition, the wireless network is not used as a mobile phone to directly access the human body. It should be absolutely safe.

3. Simple Construction Method
Generally, a wireless network is equipped with a wireless network card and an AP, so that network resources can be shared in a wireless mode in combination with the existing wired architecture, setup costs and complex procedures are much lower than traditional wired networks. If only the peer network of several computers is used, do not use an AP. You only need a wireless network card for each computer. AP is short for accesspoint, which is generally translated as "Wireless Access Node" or "bridge ". It serves as a bridge between a wireless workstation and a wired local area network in the MAC of the media access control layer. With an AP, it is like a hub in a wired network. A wireless workstation can be quickly and easily connected to the network. Especially for the use of broadband, WiFi is more advantageous. After a Wired Broadband Network (ADSL, residential LAN, etc.) arrives, connect to an AP, and then install a wireless network card on the computer. An AP in a common household is sufficient. Even after the user's neighbor is authorized, the Internet can be accessed through sharing without adding a port.

4. Long-distance work
Although Wireless WiFi is far from working, the actual working distance of 802.11b can reach more than 100 meters in the case of complete network construction, in addition, it solves the problem of data correction and error codes during high-speed mobile. The switchover and security authentication between Wi-Fi devices and devices, devices and base stations are well solved.

Development and Future of WiFi

In the past two years, the number of wireless APS has increased rapidly, and the convenience and efficiency of wireless networks have enabled the rapid popularization of wireless APs. In addition to the existing AP in some public areas, there are already precedent in foreign countries to build a man based on wireless standards. Therefore, the wireless position of wifi will become stronger and stronger.

Wifi is currently the mainstream standard for wireless access, but how far will WiFi go? With intel's strong support, Wi-Fi has already taken over. It is compatible with WiMAX of existing WiFi, and is equivalent to 802.11x of WiFi, while WiMAX is 802.16x. Compared with the former, WiMAX has a longer transmission distance, wider band selection, and higher access speed. It is expected to become a mainstream standard for wireless networks in the next few years, intel plans to use this standard to build wireless wide-area networks in the future. This is a qualitative change compared with the current wireless LAN or man, and the existing equipment can still be supported to protect every penny of investment.

All in all, the demand for mobile connections between home and small office network users is the driving force behind the growth of the wireless LAN market, developed countries such as the United States and Japan are still the regions with the largest number of Wi-Fi users. However, with the popularization of e-commerce and mobile office, low-cost WiFi, it will surely become an inevitable choice for users who need to connect to the network at any time.

Recently, the industry has heard that Wi-Fi has experienced a crisis of survival. According to foreign media reports, many companies are still investing heavily in WiFi recently, but few are making profits. It is reported that many companies went bankrupt due to wifi. Not long ago, r wireless also gave up the business. So is the profit of wifi really in crisis?

It is undeniable that the commercial use of wifi technology has encountered many difficulties. On the one hand, it is restricted by the limitations of wifi technology, such as its roaming, security, and billing methods. On the other hand, due to the unclear profit model of WiFi, if WiFi is used as a single network, the lack of commercial users will make the investment income of network construction relatively low, therefore, it also affects the enthusiasm of telecom operators. However, from the perspective of wifi technology positioning, I believe that for telecom operators, the positioning of wifi technology is mainly complementary to high-speed Wired Access Technology and will gradually become a supplement to cellular mobile communication in the future.

Although the commercial use of wifi technology has encountered some difficulties, this advanced technology cannot provide all functional communication systems. It can be said that only the complementary use of various access methods can bring economic, reliable and effective. Therefore, it can play an important complementary role in 3G in a specific region and scope. The combination of WiFi and 3G technology will have broad development prospects.

Wifi is a supplement to high-speed Wired Access Technology

Currently, wired access technologies include Ethernet and xDSL. As a supplement to high-speed wired access technology, Wi-Fi technology has the advantages of mobility and low price. WiFi technology is widely used in wired access areas that require wireless extension, such as temporary venues. Due to the differences in data rate, coverage, and reliability, WiFi technology can be used as a supplement to high-speed Wired Access Technology in broadband applications. The key technologies undoubtedly determine how much WiFi can be supplemented. Currently, OFDM, MIMO (multi-input and multi-output), smart antennas, and software radio are all applied to wireless LAN to improve Wi-Fi performance. For example, the 802.11n plan combines MIMO with OFDM, this doubles the data rate. In addition, the improvement of antennas and transmission technology greatly increases the transmission distance of the wireless LAN, which can reach several kilometers.

Wi-Fi is a supplement to cellular mobile communication. Secondary positioning of wifi technology-supplement of cellular mobile communication. Cellular Mobile Communication provides a wide range of coverage, high mobility, and low data transmission rates. It can use the features of Wi-Fi high-speed data transmission to make up for its own data transmission rate limitations. Wi-Fi not only uses the complete authentication and billing mechanism of the cellular mobile communication network, but also supports multi-access Switching Based on the wide coverage of the cellular mobile communication network. In this way, WiFi and cellular mobile communication can be integrated, making the operation of cellular mobile communication more icing on the cake and further expanding its business volume.

Wifi is a supplement to the existing communication system and can be seen as a supplement to 3G. Wireless access technology mainly includes IEEE 802.11, 802.15, 802.16, and 802.20 standards, which respectively refer to WLAN, wireless network WPAN: Bluetooth and UWB, wireless MAN: wiMAX and broadband mobile access to WBMA. Generally, WPAN provides connections with extremely close wireless high data transmission rates; wman provides Metro coverage and high data transmission rates; WBMA provides wide coverage, high mobility, and high data transmission rates; wiFi provides hotspot coverage, low mobility, and high data transmission rates.

For telecom operators, the positioning of wifi technology is mainly used as a supplement to high-speed Wired Access Technology and will gradually become a supplement to cellular mobile communication. Of course, there is also a small amount of competition between WiFi and cellular mobile communication. On the one hand, IP voice terminals used for WiFi have already entered the market, which has an alternative effect on cellular mobile communication. On the other hand, with the development of cellular mobile communication technology, WiFi public applications in hotspot areas may also be partially replaced by cellular mobile communication systems. However, in general, they are co-existent. For example, in some special cases, high-speed data transmission must rely on WiFi, such as the internal Wireless LAN of the aircraft proposed by Boeing; in other cases, using WiFi is more economical, such as implementing a wireless LAN inside a high-speed train.

In addition, from the perspective of the current WiFi technology, the popularity of public access is growing rapidly with the help of operators, but there are few users and there is a lack of effective profit models, so that WiFi shows a false phenomenon. Therefore, although WiFi is a new bright spot in the communication industry, it should be mainly positioned as a supplement to the existing communication system. If the hype is overheated, there may be excessive investment and idle resources in a relatively small market. According to reports, T-Mobile mobile communication companies in the United States operate "hot spots" in more than 2000 Starbucks coffee shops, on average, less than two people use each day, for this reason, operators spend hundreds of dollars each month.

In addition to existing applications such as Internet access and email reception, public access services do not provide dedicated, urgent, and necessary application services for users, this makes it difficult for consumers to attract a large number of user groups. The history of communication development over the past century has proved that the use of a communication system with all functions is not desirable. The mixed use of various access methods can improve the economy, reliability, and effectiveness at the same time. Undoubtedly, the third generation cellular mobile communication (3G) technology is a perfect system with high technical advancement, strong business capabilities, and wide application. However, WiFi can play an important complementary role in 3G in a specific region and scope. The combination of WiFi and 3G technology has broad development prospects.