Establishment and management of wireless LAN in intelligent community

WLAN is the abbreviation of Wirelesslocalareanetworks, namely wireless local area network. is a wireless technology to replace the former wired network of new means, can provide the traditional wired LAN all the features.

1, Wireless LAN Introduction

WLAN is a combination of computer network and wireless communication technology, is a subset of universal wireless access, can support a higher transmission rate (up to 2-108mbps). The use of radio frequency orthogonal frequency Division multiplexing (OFDM), Direct sequence spread spectrum (DSSS) or frequency hopping spread spectrum (UWBT) technology can achieve a fixed, semi mobile and mobile network terminal to the Internet for a long distance of high-speed connection access.

The design scheme of the intelligent community is based on the design of the cell, the coverage of the wireless network is higher, the requirement of the hardware equipment is high, and the omni-directional antenna and directional reflector antenna should be used together. In the community must also be equipped with a large number of AP, to ensure that users at any time, any place can use the wireless network. Such a design requires a reasonable planning of the network, hardware and system configuration to be reasonable. The use of MAC address access control and secure VPN application software between the client and the network, combined with the 128-bit WEP encryption mechanism between wireless networks, can ensure maximum security.

2, the basic structure of WLAN and related terminology

2.1 Introduction to Wireless network technology

With the rapid development of the network, the popularity of notebook computers, the demand for mobile office more and more high. Traditional wired LAN to be limited by wiring, if there is no reservation in the building lines, wiring and commissioning of the project will be very large, and the line is easy to damage, to maintain and expansion and other inconvenience, the network in the relocation and movement of the nodes is also very troublesome. Therefore, the wireless LAN with high efficiency and flexible networking has emerged.

Wireless LAN is the technology of using wireless technology to realize fast access Ethernet. Looking at the current market, IEEE802.11B technology in the performance, price in all aspects of the Bluetooth, HomeRF and other technologies, and gradually become the wireless access to the most widely used Ethernet standards.

2.2 Advantages of wireless network

Compared with the wired network, the main advantage of WLAN is not limited by the wiring conditions, so it is very suitable for the needs of mobile office users, with broad market prospects. It has been expanding to more industries from the traditional health care, inventory control and management services, and has even begun to enter the family and educational institutions. IEEE802.11 specified the launch power can not exceed 100 MW, the actual launch power of about 60-70 MW, while the mobile phone power of about 200 MW to 1 watts, hand-held walkie-talkie up to 5 watts. And the way wireless networks are used is not as direct as a phone to the human body, so it's safe.

2.3 Protocol of the wireless network

The most common are ieee802.11,ieee802.11a, ieee802.11b, ieee802.11g. Among them: IEEE802.11 is a wireless LAN standard originally developed by IEEE (Institute of Electrical and Electronics Engineers). IEEE802.11B is also known as Wi-Fi, using open 2.4GHz Direct sequence spread spectrum, the maximum data transfer rate of 108Mbps, can also be based on the signal strength of the transmission rate of 54Mbps, 11Mbps, 5.5Mbps, 2Mbps and 1Mbps bandwidth. No straight transmission range for the outdoor maximum of 300 meters, indoor barriers in the case of the maximum 100 meters, is now used most of the transport protocol.

2.4 Working mode of Wireless LAN

The working mode of WLAN is generally divided into two kinds, infrastructure and ad-hoc. Infrastructure refers to the working mode of interconnection via AP (Accesspoint), that is, the AP can be viewed as a hub (hub) in a traditional LAN. Ad-hoc is a special mode of operation, which makes it possible to set up a network of wireless network cards that need to communicate with each other, so that the AP can not be used to form a special mode of wireless networks application. Several computers installed wireless network card, can achieve mutual connection, resource sharing purposes.

The basic component of 2.5WLAN

Generally set up a wireless network is the basic equipment is a wireless card and an AP, so can be wireless mode, with the existing wired framework to share network resources. If only a few computers of the peer network, but also do not have AP. Only the wireless card is required for each computer. AP for Accesspoint Short, generally translated as "Wireless access Node", or "bridge." It is mainly in the media access control layer Mac plays the wireless workstation and the cable local area Network Bridge. With AP, like the hub of a general wired network, wireless workstations can be quickly and easily connected to the network.

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