Wireless Internet devices mean that devices (such as laptops, mobile phones, IPADs, etc.) are connected to the Internet through wireless means. It doesn't have to drag a network cable to access the Internet like a desktop computer.
Wireless Network Standards for Wireless Internet Devices
1. The type of Internet access of the wireless Internet device
There are two types of wireless Internet access, one is to enable data function through mobile phone, and the other is to use computer to reach wireless Internet access through mobile phone or wireless network card. Speed depends on different technologies used, terminal support speed and signal strength.
Another wireless Internet access mode is a wireless network device, which is a wireless Internet access mode constructed by a wireless AP and a wireless network card based on a traditional local area network.
2. Internet access form of wireless Internet devices
2.1 One is 802.1X, which is connected to the AP through a wireless network card, and the typical application is wi-fi. Called a wlan connection, it connects to the local area network and the Internet through a gateway. 802.1g and 54M connection speeds are currently commonly used. General hotels and companies will do this wireless coverage.
2.2 One is GPRS, directly dial CMnet or wap to access the Internet through GPRS mobile phone or SIM card, in which dialing the network can connect to the website, and WAP needs an agent. The network speed seems to be 115K, slow or slow, but convenient. You can call where there is a signal.
2.3 One is CDMA, which is similar to gprs, faster than GPRS, mostly through card, and the connection speed is around 230K.
3. Internet access method of wireless Internet device
One is the latest 3G network, namely TD-SCDMA of China Mobile, CDMA2000 of Telecom, or WCDMA of China Unicom! Speeds are comparable to broadband. The theoretical speed of mobile TD-SCDMA is 2.8M, the actual speed is 100-200k/s, the theoretical speed of Telecom 3G-CDMA2000 (EVDO) is 3.1M, the actual download speed is 100-300k/s, and the theoretical speed of Unicom WCDMA is about 7.2M-14.4M.
4. Types of wireless internet device
In a wireless local area network, common devices include wireless network cards, wireless bridges, and wireless antennas.
4.1 Wireless network card
The function of the wireless network card is similar to that of the network card in the Ethernet. As the interface of the wireless local area network, it realizes the connection with the wireless local area network. According to the different interface types, wireless network cards are mainly divided into three types, namely PCMCIA wireless network card, PCI wireless network card and USB wireless network card.
PCMCIA wireless network card is only suitable for notebook computers, supports hot swap, and can realize mobile wireless access very conveniently.
The PCI wireless network card is suitable for ordinary desktop computers. In fact, the PCI wireless network card is just a common PCMCIA card inserted into the PCI adapter card.
The USB interface wireless network card is suitable for notebooks and desktops, and supports hot swapping. If the network card has an external wireless antenna, then the USB interface is a better choice.
4.2 Wireless Bridge
Understand the role of a wireless bridge, it can be used to connect two or more independent network segments, these independent network segments are usually located in different buildings, hundreds of meters to tens of kilometers apart. So it can be widely used in the interconnection between different buildings. At the same time, according to different protocols, wireless bridges can be divided into 802.11b or 802.11G in the 2.4GHz band and 802.11a wireless bridges in the 5.8GHz band. The wireless bridge has three working modes, point-to-point, point-to-multipoint, and relay connection. Especially suitable for long-distance communication in the city.
Under the condition of no tall obstacles (mountains or buildings), one-to-one speed networking and temporary networking for field operations. Its working distance depends on the environment and the antenna, and the point-to-point microwave interconnection is now 7km. A pair of 27dbi directional antennas can achieve 10km point-to-point microwave interconnection. The 12dbi directional antenna can realize point-to-point microwave interconnection of 2km; a pair of wireless bridges that only realize the function of the link layer are transparent bridges, while the 24dbi directional antenna with network layer functions such as routing can realize heterogeneous The devices connected to the network are called wireless routers, which can also be used as layer 3 bridges.
Wireless bridges are usually used outdoors, mainly for connecting two networks. It is impossible to use only one wireless bridge, and more than two are required, while APs can be used alone. The wireless bridge has high power, long transmission distance (up to about 50km), strong anti-interference ability, etc. It does not have its own antenna, but is generally equipped with a parabolic antenna to achieve long-distance point-to-point connection.
4.3 Wireless Antenna
When the computer is far away from the wireless AP or other computers, as the signal weakens, or the transmission rate drops significantly, or the communication between the computer and the AP or other computers cannot be realized at all, at this time, the wireless antenna must be used for the received signal. Or the transmitted signal is gain (amplified).
There are many types of wireless antennas, but there are two common ones. One is an indoor antenna, which has the advantage of being convenient and flexible, but the disadvantage is that the gain is small and the transmission distance is short; the other is an outdoor antenna. There are many types of outdoor antennas, one is a progressive directional antenna, and the other is a rod-shaped omnidirectional antenna. The advantage of outdoor antenna is long transmission distance. More suitable for long-distance transmission.
5. Wireless Network Standards for Wireless Internet Devices
In order to solve the problem of interconnection of various wireless network devices, the American Institute of Electrical and Electronics Engineers (IEEE) has introduced the IEEE802.11 wireless protocol annotation. At present, 802.11 mainly includes three standards: 802.11b, 802.11a, and 802.11g. The first launch is 802.11b, its transmission speed is 11MB/s, the maximum distance is 300 meters outdoors, and about 50 meters indoors. Because its connection speed is relatively low, the 802.11a standard was introduced later, and its connection speed can reach 54MB/s. However, due to the incompatibility between the two, some wireless network devices that have already purchased the 802.11b standard cannot be used in the new 802.11a network, so the IEEE officially launched 802.11g, which is fully compatible with the 802.11b standard and compatible with the 802.11a rate. standard, so that through 802.11g, the original 802.11b and 802.11a standard equipment can be used in the same network. Like 802.11b, IEEE802.11g also works in the 2.4GHz frequency band, which is 5 times faster than the current general 802.11b speed, and is fully compatible with 802.11. It is recommended to find out whether it supports this protocol standard when purchasing equipment. Choose the one that suits you, the 802.11g standard has now begun to spread.
6. Wireless network for wireless Internet devices
6.1 Wireless Personal Area Network (WPAN): Wireless Personal Area Network stands for Bluetooth (Bluetooth), the characteristic transmission distance is less than 10m, the transmission rate is about 1Mbps, and the development rate of UWB is faster;
6.2 Wireless Local Area Network (WLAN): Wireless Local Area Network represents the 802.11 series, the characteristic transmission distance is less than 100m, the transmission rate is about 1M-54Mbps, and the development rate of 802.11n is faster;
6.3 Wireless Metropolitan Area Network (WMAN): Wireless Metropolitan Area Network represents WiMax, the characteristic transmission distance is less than 5km, and the transmission rate is about 70Mbps. The development is now slowly in application;
6.4 Wireless Wide Area Network (WWAN): Wireless Wide Area Network represents the wireless network of China Unicom, characterized by a transmission distance of <15km, a transmission rate of about 3Mbps, and a faster development speed.
Generally speaking, wireless Internet access refers to WLAN and WWAN. WLAN is to connect Intelnet through wireless access points; WWAN is to go to the business hall of China Mobile or China Unicom to handle related services.