Wireless lecture1


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The local area technologies as 1-WLAN(Wireless Local Area Network) with moderate bandwidth. And WiMax
2.The large area technologies as GSM, GPRSor UMTS, LTEwhich have much higher bandwidth.

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Wireless lecture1

  1. 1. 1Eng: Mohammed Hussein
  2. 2. Wireless TechnologyEng: Mohammed Hussein2 WirelessTechnology can make the businesses more flexible andcheaper for sending and receiving data in short time. Increasing efficiency in the companies, and makes efficient and isalmost very economical. Users have access easier at their offices. Now at home, the users dont need to use cables to have internetaccess. Reduced the costs due to cheaper cost of install and maintains. Mobility is very high for users, they can move inside the networkwithout sitting at one place.Avoiding LAN restrictions
  3. 3. Wireless Technology Classifications1. The local area technologies as WLAN(Wireless Local Area Network) withmoderate bandwidth. And WiMax2. The large area technologies as GSM,GPRS or UMTS, LTE which havemuch higher bandwidth.3Eng: Mohammed Hussein
  4. 4. Data transmissionEng: Mohammed Hussein4 SMS FAX E-mail Internet Multimedia114 kb/sVoice +SMS +MMIP9.6 kb/sVoice +SMSCircuit-SwitchingTimePacket-SwitchingMB
  5. 5. IEEE 802.11 (WLAN) ArchitectureESSBSS BSSIBSSAPAPAP: Access point, BSS : Basic Set service, ESS : Extented Set Service, IBSS Independent BSS.5 Eng: Mohammed Hussein
  7. 7. General Packet Radio Service (GPRS) ?Eng: Mohammed Hussein7
  8. 8. ScopeEnhancedalgorithmsFairness and QoSover wirelessto SatisfyApplicationsrequirements8 Eng: Mohammed Hussein
  9. 9. WLAN?Access Port SwitchMainCorporateBackboneServerServerServeriPaqNotebookPalmPilotMobile PhoneNotebook9 Eng: Mohammed Hussein
  10. 10. IEEE 802.11 Frequency : band 2,4 GHz; Infrastructure or Ad-hoc IEEE 802.11 is Cellular10Eng: Mohammed Hussein802.11 WLANs required centralized access points to mediate the wirelessconnection.nodes are limited in power, computational capacities and memory.
  11. 11. IEEE 802.11802.11DSSSFHSSIR802.11b 802.11g 802.11a802.11 – 802.11e – 802.11i802.11fMAC LayerPhysical LayerLLC 802.211 Eng: Mohammed Hussein
  12. 12. WLAN 1990 : WLAN Project IEEE (Institute of Electrical and ElectronicsEngineers) : IEEE 802.11 WiFi IEEE 802.15IEEE 802.16 WiMAX Hiperlan (High Performance Local Area Network) HiperLAN12Eng: Mohammed Hussein
  13. 13. 3 NetworkIP Routing ProtocolsAODV , DSR , DSDV,…2Data Link1 Physical (PHY)LLC 802.2MAC 8024 Transport5 Session6 Presentation7 ApplicationFigure :OSI layers with MAC and PHY details802.3CSMA/CD802.4Token Bus802.5Token Ring802.11WirelessLANLogical Link ControlNetwork layersEng: Mohammed Hussein13
  14. 14. SME/MLME = MAC Control / ManagementCoordination Function(DCF, PCF , HCF, ..) CSMA/CA802.11 Media Access Control (MAC)802.11 Physical Layer (PHY)802.11a54 Mbps/5GHz802.11b11 Mbps/2.4GHzPLMEPacketTransfer Function802.11g54 Mbps/2.4GHz802.11e – Quality of ServiceSync, powersave, BeaconSegmentation & Reassembly802.11legacy2 Mbps/2.4GHzFHSSS-Band ISMDSSSS-Band ISMOFDMC-Band ISMOFDMS-Band ISM802.11n54-600Mbps/2.4 or5 GHzOFDMMIMO14Eng: Mohammed Hussein
  15. 15. Media Access Control (MAC)Eng: Mohammed Hussein15 The MAC is the way to transfer the data safely when there is morethan one node accessing a channel simultaneously . The MAC have some techniques such as: Distributed Coordination Function (DCF) used by both methods Ad-Hoc mode or Infrastructure mode. With asynchronous transmissiondata service. Point Coordination Function (PCF) used only by Infrastructure mode.With both asynchronous and time-bounded service
  16. 16. Access MethodMAC layer: DCF (Distributed Coordination Function) :based on CSMA/CA PCF (Point Coordination Function) : based on polling16Eng: Mohammed Hussein
  17. 17. The Medium ElementsNext FrameFrameDIFSPIFSSIFSDIFSTimeDefer AccessContentionWindowBackoff Slot timeMedium is available17DCF inter-frame spacing (DIFS) : between the end of one transmission and another nextround cycle transmission in Ad-Hoc modeShort inter-frame spacing (SIFS) : has a high priority and comes after frames such as(RTS, CTS, ACK).PCF inter-frame spacing (PIFS) : between the end of one transmission and another next roundcycle transmission in Infrastructure modeMedium is BusyEng: Mohammed Hussein
  18. 18. Wireless Problems18 Eng: Mohammed Hussein
  19. 19. Hidden Terminal ProblemEng: Mohammed Hussein19BA CThe transmissions from node A and node C collide at thereceiver node B . (in the same time)
  20. 20. Exposed Terminal ProblemEng: Mohammed Hussein20BA C DWait themedium is busyThe node C senses the medium is busy, therefore node C waits unnecessarilytime before it begins transmitting to node D.So the waiting here is not required and node C is exposed to node B.
  21. 21. CSMA/CA PROTOCOLEng: Mohammed Hussein21The nodes throughputs are measured in the CSMA/CA by a collisionsand idle slots resulting from Backoff algorithm for each CW period.The CSMA/CA is algorithm for IEEE 802.11 DCF, simply listen-before-talk scheme.N+1-th PacketTransmissionCollisionDIFSSIFS DIFSN-th PacketTransmission ACK ACKCollisionIdle Backoff Slots(at each contention period)Virtual Transmission TimeSIFS DIFSCollision
  22. 22. Node 1Node 2Node 3Node 4TimeDIFSDCF (NAV , RTS, CTS, ACK )DIFSNode 5DataData General data frameBackoff slot timeACKRTSCTSSIFSSIFSSIFSDefer AccessNode 4increase2 slotmoreSIFSDataACKCTSRTS ACKRequest To Send FrameNAV (RTS)NAV (CTS)NAV(data)RemainingBackoffClear To Send FrameClear To Send FrameBackoffNAV NAV timerNAVupdates22Eng: Mohammed Hussein
  23. 23. (PCF) infrastructure modeThe idea of this access method is that the access point poolsits mobile nodes corresponding to a list.For avoiding problems with the two DCF access methodsthe PCF-IFS (PIFS) are used.They grant an access point priority access to the medium23 Eng: Mohammed Hussein
  24. 24. Beacon in infrastructure mode Synchronization in infrastructure mode is very easy. TheAccess Point (AP) regularly sends out a synchronization packet(beacon). If the medium is busy the AP just waits for a free PIFS frame24 Eng: Mohammed Hussein
  25. 25. Server(internet)802.11 frame2Bytes 2 6 6 6 2 6 0-2312 4FrameControlDuration / IDAddress 1Address 2Address 3SequenceControlPayload(Frame Body)CRCAddress 4MAC Header25Eng: Mohammed Hussein
  26. 26. framecontroldurationaddress1address2address4address3payload CRC2 2 6 6 6 2 6 0 - 2312 4seqcontrol802.11 frame: addressingAddress 2: MAC addressof wireless host or APtransmitting this frameAddress 1: MAC addressof wireless host or APto receive this frameAddress 3: MAC addressof router interface towhich AP is attachedAddress 3: used onlyin ad hoc mode26Eng: Mohammed Hussein
  27. 27. BSS1BSS2DS ( Distribution System)STA 2SSSTA 3DSSDSS802.X LANinternetDSSESSSTA 1STA 4802.11 MAC/PHY802.11 MAC/PHYSS :Station servicesSSSTA :StationDSS: Distribution System servicesESS: Extended Service SetBSS: Basic Service SetPortal27Eng: Mohammed Hussein
  28. 28. Infrastructure network28 Eng: Mohammed Hussein
  29. 29. Handover between APs29 Eng: Mohammed Hussein
  30. 30. Ad-Hoc NetworkIBSS (Independent Basic Service Set)30 Eng: Mohammed Hussein
  31. 31. Ad-Hoc NetworkEng: Mohammed Hussein31
  32. 32. Ad Hoc classification32 Eng: Mohammed Hussein
  33. 33. 33 Eng: Mohammed Hussein
  34. 34. Sensor nodeInternetManager NodeuserSink NodeThe environment Sensors fieldTargetWireless Sensor Network34Eng: Mohammed Hussein
  35. 35. Sensor NodeEng: Mohammed Hussein35
  36. 36. WiMax ScenarioEng: Mohammed Hussein36
  37. 37. Scenarios for integratedWiFi and WiMAX networksEng: Mohammed Hussein37
  38. 38. Summary of QoSEng: Mohammed Hussein38
  39. 39. COMNET IIICOMNET III is a commercial off-the-shelfapplication whose function is to allow users toestimate the performance characteristics ofcomputer based networks.A network description is created graphically using awindow interface, and no actual programming isrequired of the user.The application was formulated primarily for themodeling of both Wide Area Networks (WANs) andLocal Area Networks (LANs).39Eng: Mohammed Hussein
  40. 40. COMNET IIIThe COMNET III application was written in theprogramming language MODSIM II using anobject-oriented design.1. RUNNING A SIMULATION2. STATISTICAL DISTRIBUTIONS AND TABLES3. REPORTS4. PLOTS AND PERCENTILESCOMNET III uses a discrete event simulationmethodology when running the simulation of anetwork model.40Eng: Mohammed Hussein
  41. 41. ReferencesEng: Mohammed Hussein41 Some Books : Second Generation Mobile And WirelessTechnologies; Black, Uyless Prentice Hall; 09/1998; WirelessPersonal Communications; A Systems Approach; Goodman,David J. Addison Wesley; 09/1997; Principles of MobileCommunication; Stuber, Gordon L. Kluwer AcademicPublishing; 6/96.
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