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Wireless LAN’sAgendaIntroductionSlide 4Slide 5Wireless NetwareSlide 7Slide 8WLAN Technologies: IEEE 802.11B, A, & GIEEE 802.11BIEEE 802.11B TopologyIEEE 802.11B Topology DiagramIEEE 802.11AIEEE 802.11A TopologyIEEE 802.11GIEEE 802.11G TopologyComparisonIEEE 802.11G BenefitsExample: “Skechers Goes Wireless”BluetoothSlide 21Media Access ControlDistributed Coordination FunctionPoint Coordination FunctionData Transmission in Physical LayerData Transmission in EfficiencySlide 27Slide 28WLAN SecuritySlide 30802.16 (WiMAX)WarDrivngQuestions & CommentsSourcesWireless LAN’sGang FongRebecca PrewittSerina RoushAgenda•Introduction•Wireless Netware•Comparison: –802.11B–802.11A–802.11G•Skechers Example•Bluetooth•Media Access Control/Data Transmission•WLAN security•802.16 – WiMAX•WarDriving•ConclusionIntroduction•WLAN’s transmit data through radio waves instead of using twisted pair or fiber optic cables•90% of companies are using wireless LAN’s today•Serve the same purpose as LAN’s; connect a series of computers in the same local area to each other and to a backbone networkIntroduction•Used only as an alternative when cabling for LAN’s was difficult or impossible•Originally WLAN hardware was so expensive that LAN’s were the logical option, but now its cheap enough to be used in homesIntroduction•NOT totally wireless...it connects wireless computers to a wired network •Advantage: enables employees to have work mobility; move their computer from one place to another in the building–Popular in airports, and universities•Large future markets are estimated to be in health care, corporate offices and the downtown area of major cities. New York City has even begun a pilot program to cover all five boroughs of the city with wireless internet.Wireless Netware•Network Interface Cards–Each computer has a wireless NIC used to connect the computer into the WLAN–Radio transceiver; sends/receives radio signals through a short range (300-500 ft)–Available for laptops as PCMCIA cards or standard cards for desktop computers; Linksys Wireless PC card 54Mbps = $54–Laptop cards are most popular; most laptops come with 802.11b network cards built in–All NIC’s in the WLAN transmit their packets to the Access Points; wireless NIC’s never communicate with each other directlyWireless Netware•Access Point (AP)–Radio transceiver; like a hub in wired Ethernet LAN’s, it connects the WLAN into wired LAN’s using 10Base-T or 100Base-T–Acts as a repeater to make sure all computer in range of the AP can hear the signals of all other computers in the WLAN.–AP retransmits the packet over the wireless or wired network to its destination–Set up several AP’s in same area to provide several different channels enabling more network capacityWireless Netware•AP Antennas–Omnidirectional; antenna that transmits in all directions (vertically & horizontally) simultaneously.•Most common is the Dipole antenna; nicknamed the “rubber duck” because of its flexibility–Directional; projects a signal in only one direction.•Signal is stronger and will carry farther than an omnidirectional because its concentrated in a narrower, focused areaWLAN Technologies:IEEE 802.11B, A, & GIEEE 802.11B•Usually called wireless Ethernet, or “Wi-Fi”•Uses radio transmission•Frequency Range: 2.4-GHz •Bandwidth: 22 MHz•Data Rates: 1 to 11 Mbps •Range: 100 to 150 metersIEEE 802.11B Topology•Logical and physical topologies same as traditional Ethernet–Physical star and Logical bus•Wireless Network Interface Card (NIC) –Radio transceiver, connects computer to WLAN•Wireless Access Point (AP)–Radio transmitter that acts like a hub•Bus-oriented shared multipoint circuit•Has ability to provide more controlled access by permitting stations to reserve time to transmit to prevent collisionsIEEE 802.11B Topology DiagramIEEE 802.11A•Work started before 802.11B, but it proved more difficult to develop a standard•Frequency Range: 5-GHz•Bandwidth: 300 MHz•Data Rates: 6, 9, 12, 18, 24, 36, 48, and 54 Mbps•Range: Becomes shorter at higher Mbps•50 meters for 6 to 12 Mbps, 15 meters for 35 to 54 Mbps•Works same as 802.11B, except at physical layerIEEE 802.11A Topology•Same as 802.11B–Set of NICs communicating with one AP•Uses frequency division multiplexing–Several APs in the same room, each operating on a different channel to provide greater network capacity–Ex.: 4 APs in one room x 54 Mbps = 216 Mpbs to be shared among computers in the roomIEEE 802.11G•Newest WLAN standard•Combines best of 802.11A and 802.11B•Frequency Range: 2.4-GHz•Data Rates: Up to 54 Mbps•Range: 100 to 150 metersIEEE 802.11G Topology•Same as 802.11B–Set of NICs communicating with one APComparisonIEEE 802.11B IEEE 802.11A IEEE 802.11GRange:Large (100 to 150 meters)Small (<50 meters)Large (100 to 150 meters)Speed: Low (<11 Mpbs) High (54 Mpbs) High (54 Mpbs)Channels: 3 channels 4-12 channels 3-6 channelsIEEE 802.11G Benefits•Backward compatible with 802.11B–802.11B devices can work w/802.11G access point•Greater effective data rates than 802.11A over longer ranges•Eventually will replace both 802.11A and B–Depending on how fast prices dropExample: “Skechers Goes Wireless”•1,500 styles and 60,000 product types within 1.5 million sq. ft. of distribution space•Physical inventory took 5 days, now 2 days because they built an 802.11b wireless network: 62 wireless access points where 225 employees work with handhelds and vehicle mounted computers that communicates with warehouse management software (runs on the mainframe)•Wireless assistance allows inventory to get traced at each step of the order-fulfillment process!Bluetooth•Bluetooth devices are small, cheap, and designed to replace short-distance cabling between devices such as: keyboards, mice, etc.•Goal: provide seamless networking of data and/or voice devices in a very small area (up to 10 meters, or 30 ft.)•Data rate = 1Mbps that can be divided into several separate voice and data channelsBluetooth•Different type of WLAN; actually a WPAN (Wireless Personal Area Network) standardized as IEEE 802.15•Topology: Piconet – consists of no more than eight devices, but can be linked to other piconets to form larger network–Piconet Master, all other devices are Slaves•Messages are sent from a slave to the master and from the master to a slave. Slaves do


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