tailieunhanh - Wireless Networks

Wireless network refers to any type of computer network that is not connected by cables of any kind. It is a method by which homes, telecommunications networks and enterprise (business) installations avoid the costly process of introducing cables into a building, or as a connection between various equipment locations.[1] Wireless telecommunications networks are generally implemented and administered using a transmission system called radio waves. This implementation takes place at the physical level (layer) of the OSI model network structure | Wireless Networks Authors: Marius Popovici Daniel Crişan Zagham Abbas Cluj-Napoca, 24 Nov. 2003 Technical University of Cluj-Napoca Group 3250 Presentation Outline Wireless Technology overview The IEEE WLAN Standards Secure Wireless LANs Migrating to Wireless LANs (Cutting the cord) Wireless? A wireless LAN or WLAN is a wireless local area network that uses radio waves as its carrier. The last link with the users is wireless, to give a network connection to all users in a building or campus. The backbone network usually uses cables Common Topologies The wireless LAN connects to a wired LAN There is a need of an access point that bridges wireless LAN traffic into the wired LAN. The access point (AP) can also act as a repeater for wireless nodes, effectively doubling the maximum possible distance between nodes. Common Topologies Complete Wireless Networks The physical size of the network is determined by the maximum reliable propagation range of the radio signals. Referred to as | Wireless Networks Authors: Marius Popovici Daniel Crişan Zagham Abbas Cluj-Napoca, 24 Nov. 2003 Technical University of Cluj-Napoca Group 3250 Presentation Outline Wireless Technology overview The IEEE WLAN Standards Secure Wireless LANs Migrating to Wireless LANs (Cutting the cord) Wireless? A wireless LAN or WLAN is a wireless local area network that uses radio waves as its carrier. The last link with the users is wireless, to give a network connection to all users in a building or campus. The backbone network usually uses cables Common Topologies The wireless LAN connects to a wired LAN There is a need of an access point that bridges wireless LAN traffic into the wired LAN. The access point (AP) can also act as a repeater for wireless nodes, effectively doubling the maximum possible distance between nodes. Common Topologies Complete Wireless Networks The physical size of the network is determined by the maximum reliable propagation range of the radio signals. Referred to as ad hoc networks Are self-organizing networks without any centralized control Suited for temporary situations such as meetings and conferences. How do wireless LANs work? Wireless LANs operate in almost the same way as wired LANs, using the same networking protocols and supporting the most of the same applications. How are WLANs Different? They use specialized physical and data link protocols They integrate into existing networks through access points which provide a bridging function They let you stay connected as you roam from one coverage area to another They have unique security considerations They have specific interoperability requirements They require different hardware They offer performance that differs from wired LANs. Physical and Data Link Layers Physical Layer: The wireless NIC takes frames of data from the link layer, scrambles the data in a predetermined way, then uses the modified data stream to modulate a radio carrier signal. Data Link Layer: Uses .