Wireless network Infrastructure

From the application requirements, the wireless network is very suitable for schools of some sites that are not easy to network wiring applications. Now most of the campus has wired LAN, how to further expand the original network, so that every corner of the campus in the network, the formation of a true sense of the campus network? This article is to introduce how to use Wireless LAN technology to form a campus network.

Wireless network Infrastructure

Wireless LAN (Wireless local area network, referred to as WLAN) technology has Bluetooth, IEEE 802.11 series, HiperLAN, HomeRF technology and so on. Among them, the current widely used technology is the IEEE 802.11 series. IEEE 802.11b can support 11Mbps shared access speed, with 2.4GHz ISM band; similar to IEEE 802.11a technology, it uses the 5GHz band, which has a high rate of 54Mbps; last year, the newly emerging IEEE 802.11G is actually a hybrid standard that adapts to the IEEE 802.11B Standard and IEEE 802.11a standard, but it's not very mature yet. In the current situation, comprehensive consideration, IEEE 802.11B regardless of the transmission distance or transmission rate has an advantage, so wireless campus network can choose the IEEE 802.11b standard.

Wireless LAN consists of wireless network cards and wireless access points (access point, referred to as AP). Wireless LAN makes use of regular LAN (such as 10/100/1000m Ethernet) and its interconnect equipment (routers, switches) to form backbone support network. The wireless access point (AP) is used to support mobile terminal (MT) movement and roaming. A desktop PC, laptop or other device with a wireless card can be connected to a wireless network.

For the client, the wireless network card as the interface of the wireless network to achieve the connection with the wireless networks. Wireless card According to the different types of interface, there are three main types: PCMCIA wireless network card (suitable for notebook computer, support hot plug), PCI wireless network card (for desktop) and USB wireless network card (for laptops and desktops, support hot-swappable).

The wireless access point is the function of bridging between the WLAN and the LAN. WLAN workstations can also roam (roaming) between different AP. If the external antenna is not added, the coverage of AP is theoretically about 250m in the field of vision. But if in the half open space, or the interval area, then about 30~50m about. Because the microwave is a straight line, so the microwave is small angle through several wall body, the wall will weaken the signal, if the wall is reinforced concrete, the signal will be weaker. Therefore, in the actual case (usually outdoors), also need to add an external gain antenna, so that the distance to reach farther, stronger signal.