tailieunhanh - Wireless LAN
A WLAN is a shared network. An access point is a shared device and functions like a shared Ethernet hub. Data is transmitted over radio waves. Two-way radio communications (half-duplex) are used. The same radio frequency is used for sending and receiving (transceiver). | CHAPTER 2: WIRELESS LAN : Introducing WLANs Wireless Data Technologies There are many different types of wireless data communications. Each of these has its advantages and drawbacks. Infrared (IR): Very high data rates, lower cost, very short distance. Narrowband: Low data rates, medium cost, license required, limited distance. Spread Spectrum: Limited to campus coverage, medium cost, high data rates. Personal communication service (PCS): Low data rates, medium cost, citywide coverage. GHz service, T-Mobile: Global System for Mobile Communication (GSM), medium cost, and worldwide coverage. Cellular, Cellular digital packet data (CDPD), Mobitex, DataTac: Low data rates, flat monthly rate, and national coverage. Wireless Data Technologies (Cont.) In today’s wireless world, there are many different types of networks offered. Each of these different networks are designed to give different coverage areas. Starting with the smallest coverage area, they are as follows: Personal Area Network (PAN) – Typically designed to cover your personal work space. Radios are typically very low powered and do not deliver options in antenna selection thus limiting the size of coverage area (typically less than 20 feet of radius). One such PAN network is Bluetooth. Good applications of this technology is communications between PC and peripheral or between wireless phone and headset. In the PAN wireless network, the customer owns 100% of the network, therefore no airtime charges are incurred. Local Area Network (LAN) – Designed to be enterprise based wireless networks allowing for complete enterprise applications to be utilized without wires. Typically delivers Ethernet capable speeds (up to 54 Mbps). In the LAN wireless network, the customer owns 100% of the network, therefore no airtime charges are incurred. Metropolitan Area Networks (MAN) – These wireless networks are deployed inside a metropolitan area allowing wireless connectivity throughout an urban area. The . | CHAPTER 2: WIRELESS LAN : Introducing WLANs Wireless Data Technologies There are many different types of wireless data communications. Each of these has its advantages and drawbacks. Infrared (IR): Very high data rates, lower cost, very short distance. Narrowband: Low data rates, medium cost, license required, limited distance. Spread Spectrum: Limited to campus coverage, medium cost, high data rates. Personal communication service (PCS): Low data rates, medium cost, citywide coverage. GHz service, T-Mobile: Global System for Mobile Communication (GSM), medium cost, and worldwide coverage. Cellular, Cellular digital packet data (CDPD), Mobitex, DataTac: Low data rates, flat monthly rate, and national coverage. Wireless Data Technologies (Cont.) In today’s wireless world, there are many different types of networks offered. Each of these different networks are designed to give different coverage areas. Starting with the smallest coverage area, they are as follows: .
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