Look at the wireless network from the wireless network card In the course of its decades of development, computer network technology has been constantly accelerating. Today, computer networks are especially At present, there are two hot spots in the field of computer network research, namely broadband technology research and wireless access technology research, especially wireless access technology has received great attention in recent years. With the vigorous development of the Internet and the increasing demand for broadband, the single and annoying cable and network cable access that has held people back and forth has been unable to meet people's needs for access methods. At this time, another way to connect to the Internet quietly came into people's attention, and in the process of the new and old centuries, a movement of "going to the Internet" was performed. This is wireless access technology. Perhaps, Future Internet access standards will also be born here. Currently, wireless access involves two aspects: wireless local area network and wireless wide area network. The former is based on wireless network technologies such as WAP, Bluetooth, and 802.11. It allows people to roam throughout the office without being constrained by network cables. However, due to the limitations of its own coverage, the application of wireless LAN is still limited to company units or industry users. The latter is mainly based on GPRS, CDMA and other wireless network technologies. Thanks to the mobile operator's communication network, it can truly achieve wireless Internet access anytime and anywhere. Regarding the interface technology of the wireless network card, because a large number of desktop computers in the LAN have wireless access requirements, the wireless LAN card using the PCI interface will still exist for a period of time, but comprehensive consideration of convenience and transmission rate will eventually make it located in the USB wireless Network card. For notebooks and mobile PCs, they have greater demand in WANs, so wireless network cards with PCMCIA interfaces and USB wireless network cards have a bright future. It can be said that whether it is a wireless local area network or a wireless wide area network, the wireless network card with USB interface has the best adaptability, and it is expected to become the focus of wireless network card development. One. Wireless network card classification introduction Before introducing the wireless network card, first summarize some of the current domestic and international popular wireless access technologies (technical details are not introduced), because different wireless access technologies must use different wireless network cards, although they Some are not marketized. Including GSM, CDMA, GPRS, CDPD, fixed wireless broadband (LMDS), DBS satellite access technology and Bluetooth, HomeRF, WCDMA, 3G, WLAN, wireless optical systems, etc. From the user's perspective, it is the wireless network card that directly deals with the wireless network. Whether it is a wireless LAN or a wireless wide area network, and regardless of how the wireless network is specifically constructed, users can easily access the network as long as they have the appropriate wireless network card. Corresponding to a wide variety of wireless access technologies, there are also a wide variety of wireless network cards. No matter what access service the wireless network service provider provides, users can enjoy wireless network services as long as they select the matching wireless network card. The wireless network cards can be classified differently from different angles. In fact, the wireless LAN cards, GPRS wireless network cards, and CDMA wireless network cards are currently used the most because there are many access technologies for various reasons (including non-technical reasons) Without becoming the dominant market, there are not many corresponding products on the market. Divided from the interface used by the wireless network card, there are PCI wireless network card (including ISA interface), USB wireless network card and PCMCIA wireless network card (including CF interface). (1) PCI wireless network card PCI wireless network card adopts PCI interface, mainly for desktop computers, and is further subdivided into true PCI wireless network card and PCI wireless network card adapter card. The true PCI wireless network card is a wireless network card that uses the PCI interface to provide wireless access. The PCI adapter card itself does not provide wireless access. Strictly speaking, it cannot be regarded as a wireless network card. It only provides a conversion function. , There is a PCMCIA interface on the adapter card, so that you can then insert the PCMCIA wireless network card. (2) USB wireless network card The Universal Serial Bus (Universal Serial Bus) standard is now the most popular short-range digital device interconnection standard. With the emergence of the USB 2.0 standard, the theoretical maximum transmission rate of the USB interface can reach 480 Mbps. The PCMCIA wireless network card corresponds to the PCMCIA interface and is mainly aimed at notebook computers. 2. Features Functionally, wireless network cards can be divided into single-mode wireless network cards and dual-mode wireless network cards. Single-mode wireless network cards can only provide wireless LAN access or wireless WAN access functions, while dual-mode wireless network cards can achieve two types of access. Into function. Most wireless network cards are single-mode. 3. Speed ​​points In terms of connection speed, wireless network cards can be divided into low-speed wireless network cards, medium-speed wireless network cards and high-speed wireless network cards. This classification is more time-sensitive, because the higher-speed network cards are now with the development of technology and the overall increase in transmission rate. , Can only be divided into general wireless network cards. The use of wireless network technology has undoubtedly made mobile office and mobile life possible. But if there is a problem with the network, the trouble will be even greater. How to build a well-functioning wireless network system. The choice of network card is undoubtedly very important. In the current market, various network cards such as colorful butterflies in the flowers are flying everywhere. How to find a network card suitable for your organization? The following will introduce the purchase of wireless network card, hoping that it can give you the direction of purchase like a compass. To purchase a wireless network card, first of all depends on the user's network environment, in order to determine which type of network card to choose. Currently, there are three types of wireless Internet access cards on the market: WLAN Internet access card, GPRS Internet access card, and CDMA Internet access card, which can meet different wireless network access needs. At the same time, there are multi-function internet cards that adapt to multiple internet access methods. Secondly, according to the user's terminal device interface type, select the appropriate network card. From the interface point of view, it is mainly divided into PCMCIA card, USB external Modem, RS232 external Modem. PCMCIA cards are mostly used for notebook users, the latter two can be used for both PC and notebook. From the perspective of the antenna, it can be divided into two types: built-in antenna and external antenna. Once again, we need to understand the brand. There are many brands of network cards. The more common ones are SIERRA ’s Aircard, Lenovo ’s “Wings of Mobileâ€, Nokia, Sony Ericsson, Panda, Capitel, BenQ, Top, Netac, Novartis, Chimei, Wiang. , As well as Abe, Benbo, HARDLINK and many other brands. Finally, when you buy a network card, you can choose with the mainstream. Because in such a relatively new field, only companies with considerable technical strength can manufacture Internet cards, create marginal advantages, and occupy a larger market share. Companies with relatively weak technological power are more involved in participation, and do not have sufficient production capacity and service capacity. Therefore, you can refer to the most popular brands at the time of selection. In the following, the three types of wireless network cards mentioned above will be introduced one by one. 1. WLAN card Wireless local area network is the product of the combination of computer network and wireless communication technology. In layman's terms, a wireless local area network (Wireless local-area network, WLAN) is to provide all the functions of a traditional wired local area network without using traditional cables. The infrastructure required for the network does not need to be buried underground or hidden in the wall However, the network can move or change according to your needs. The reason why it is also called a local area network is because it will affect the transmission range due to the distance between the wireless connection device and the computer. Therefore, it must be within the area to connect to the network. The WLAN network card is a network card used in a wireless local area network, mainly adopting Bluetooth technology, 802.11a, 802.11b technology, and 802.11g technology serving the Wi-Fi standard. 802.11b technology has become the de facto standard in the wireless LAN market. The transmission rate in the LAN can reach 11M, covering an area of ​​100 meters. 802.11g technology is more common in wireless LAN cards that appeared at the beginning of the year, and the transmission rate can reach 54M, but such products are still rare in the market. At present, the purchase of wireless LAN cards is mainly for enterprise purchases because of the cooperation with the purchase of APs. In many business sites that provide wireless Internet access, users can rent the network card of the operator to use, and can also receive corresponding services. The price of an AP is around 10,000 yuan, and the price of a network card is around 1,000 yuan. 2. GPRS network card Since China Mobile launched GPRS (General Packet Radio Service) services, such as "high-speed transmission", "always-on", "according to flow rate" and other publicity and reports that are superior to GSM communication methods, GPRS-enabled mobile phones And related products have also emerged, including GPRS PC cards for business people and the chasing new family. Notebooks, PDAs and other devices equipped with this product can free users from the shackles of telephone lines and network cables and enjoy wireless Internet surfing anytime, anywhere pleasure. Although the GPRS PC card has high commercial and practical value in some fields, for now, its user group is relatively small, and the prices of various brand products are generally high. 3. CDMA network card There are currently two types of wireless WAN in China, GPRS and CDMA 1X. The highest rate theoretically supported by China Mobile's GPRS network is 171.2Kbps, which is achieved when the coding method is CS-4, and the wireless environment is good and the channel is sufficient. When GPRS reaches the theoretical maximum value of 171.2Kbps, it can already fully support some applications with high bandwidth requirements such as multimedia image transmission services, but the actual data transmission rate is affected by factors such as network coding and terminal support. However, the actual access speed of users is now 15Kbps ~ 40Kbps. After using the data acceleration system, the rate can be stabilized between 60Kbps ~ 80Kbps. China Unicom's CDMA 1X network is a wireless Internet-based business launched by China Unicom on March 28. Unicom described it as "broadband in the palm" during its publicity; it can reach 153K faster in a general environment, twice the speed of GPRS. The frequency of CDMA is continuous, not pulsed. The quality of the call is also recognized by everyone, and the speed and price of using its wireless Internet access also have certain advantages. to sum up: Does the above introduction make you have a sudden and cheerful feeling? Nothing is unachievable. As long as we pay attention to observation and study, and are good at accumulating previous experience and identification tips of experts, we will be able to choose high-quality and cheap products according to our own will. Network products are especially important for modern people. When an organization wants to build a network system, we hope that our introduction will bring you convenience.
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The Internet has penetrated into all areas of society and all aspects of people's lives. It is no exaggeration to say that today's world cannot leave the network.
1. Interface points
(3) PCMCIA wireless network card
two. Wireless network card classification introduction 