PowerPoint PresentationCh. 6: Wireless and Mobile NetworksChapter 6 outlineElements of a wireless networkSlide 5Slide 6Slide 7Characteristics of selected wireless linksSlide 9Slide 10Wireless network taxonomySlide 12Wireless Link Characteristics (1)Wireless Link Characteristics (2)Wireless network characteristicsCode Division Multiple Access (CDMA)CDMA encode/decodeCDMA: two-sender interferenceSlide 19IEEE 802.11 Wireless LAN802.11 LAN architecture802.11: Channels, association802.11: passive/active scanningIEEE 802.11: multiple accessIEEE 802.11 MAC Protocol: CSMA/CAAvoiding collisions (more)Collision Avoidance: RTS-CTS exchange802.11 frame: addressingSlide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Cellular networks: the first hopSlide 38Slide 39Slide 40Slide 41What is mobility?Mobility: vocabularyMobility: more vocabularyHow do you contact a mobile friend:Mobility: approachesSlide 47Mobility: registrationMobility via indirect routingIndirect Routing: commentsIndirect routing: moving between networksMobility via direct routingMobility via direct routing: commentsAccommodating mobility with direct routingSlide 55Mobile IPMobile IP: indirect routingMobile IP: agent discoveryMobile IP: registration exampleSlide 60Handling mobility in cellular networksSlide 62Slide 63Slide 64Slide 65Slide 66Mobility: GSM versus Mobile IPWireless, mobility: impact on higher layer protocolsChapter 6 summaryChapter 6Wireless and Mobile NetworksComputer Networking: A Top Down Approach 6th edition Jim Kurose, Keith RossAddison-WesleyMarch 2012A note on the use of these ppt slides:We’re making these slides freely available to all (faculty, students, readers). They’re in PowerPoint form so you see the animations; and can add, modify, and delete slides (including this one) and slide content to suit your needs. They obviously represent a lot of work on our part. In return for use, we only ask the following:If you use these slides (e.g., in a class) that you mention their source (after all, we’d like people to use our book!)If you post any slides on a www site, that you note that they are adapted from (or perhaps identical to) our slides, and note our copyright of this material.Thanks and enjoy! JFK/KWR All material copyright 1996-2012 J.F Kurose and K.W. Ross, All Rights ReservedWireless, Mobile Networks6-1Wireless, Mobile Networks6-2Ch. 6: Wireless and Mobile NetworksBackground: # wireless (mobile) phone subscribers now exceeds # wired phone subscribers (5-to-1)!# wireless Internet-connected devices equals # wireline Internet-connected deviceslaptops, Internet-enabled phones promise anytime untethered Internet accesstwo important (but different) challengeswireless: communication over wireless linkmobility: handling the mobile user who changes point of attachment to networkWireless, Mobile Networks6-3Chapter 6 outline6.1 Introduction Wireless6.2 Wireless links, characteristicsCDMA6.3 IEEE 802.11 wireless LANs (“Wi-Fi”)6.4 Cellular Internet Accessarchitecturestandards (e.g., GSM)Mobility6.5 Principles: addressing and routing to mobile users6.6 Mobile IP6.7 Handling mobility in cellular networks6.8 Mobility and higher-layer protocols6.9 SummaryWireless, Mobile Networks6-4Elements of a wireless networknetwork infrastructureWireless, Mobile Networks6-5wireless hostslaptop, smartphonerun applicationsmay be stationary (non-mobile) or mobilewireless does not always mean mobilityElements of a wireless networknetwork infrastructureWireless, Mobile Networks6-6 base stationtypically connected to wired networkrelay - responsible for sending packets between wired network and wireless host(s) in its “area”e.g., cell towers, 802.11 access points Elements of a wireless networknetwork infrastructureWireless, Mobile Networks6-7 wireless linktypically used to connect mobile(s) to base stationalso used as backbone link multiple access protocol coordinates link access various data rates, transmission distanceElements of a wireless networknetwork infrastructureWireless, Mobile Networks6-8Characteristics of selected wireless linksIndoor10-30mOutdoor50-200mMid-rangeoutdoor200m – 4 KmLong-rangeoutdoor5Km – 20 Km.056.384145-11542G: IS-95, CDMA, GSM2.5G: UMTS/WCDMA, CDMA2000802.15802.11b802.11a,g3G: UMTS/WCDMA-HSPDA, CDMA2000-1xEVDO4G: LTWE WIMAX802.11a,g point-to-point200802.11nData rate (Mbps)Wireless, Mobile Networks6-9 infrastructure modebase station connects mobiles into wired networkhandoff: mobile changes base station providing connection into wired networkElements of a wireless networknetwork infrastructureWireless, Mobile Networks6-10ad hoc modeno base stationsnodes can only transmit to other nodes within link coveragenodes organize themselves into a network: route among themselvesElements of a wireless networkWireless, Mobile Networks6-11Wireless network taxonomysingle hopmultiple hopsinfrastructure(e.g., APs)noinfrastructurehost connects to base station (WiFi,WiMAX, cellular) which connects to larger Internetno base station, noconnection to larger Internet (Bluetooth, ad hoc nets)host may have torelay through severalwireless nodes to connect to larger Internet: mesh netno base station, noconnection to larger Internet. May have torelay to reach other a given wireless nodeMANET, VANETWireless, Mobile Networks6-12Chapter 6 outline6.1 Introduction Wireless6.2 Wireless links, characteristicsCDMA6.3 IEEE 802.11 wireless LANs (“Wi-Fi”)6.4 Cellular Internet Accessarchitecturestandards (e.g., GSM)Mobility6.5 Principles: addressing and routing to mobile users6.6 Mobile IP6.7 Handling mobility in cellular networks6.8 Mobility and higher-layer protocols6.9 SummaryWireless, Mobile Networks6-13Wireless Link Characteristics (1)important differences from wired link ….decreased signal strength: radio signal attenuates as it propagates through matter (path loss)interference from other sources: standardized wireless network frequencies (e.g., 2.4 GHz) shared by other devices (e.g., phone); devices (motors) interfere as wellmultipath propagation: radio signal reflects off objects ground, arriving ad destination at slightly different times…. make communication across (even a point to point) wireless link much more “difficult”Wireless, Mobile Networks6-14Wireless Link Characteristics (2)SNR: signal-to-noise ratiolarger SNR – easier to extract signal from noise (a “good
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