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Wireless Communication

Wireless Communication. Hwajung Lee Key Reference: Prof. Jong-Moon Chung’s Lecture Notes at Yonsei University. Wireless Communications. Bluetooth Wi-Fi Mobile Communications LTE LTE-Advanced. M obil e Co mm uni ca tion s Handover. M obil e Co mm uni ca tion s.

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Wireless Communication

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  1. Wireless Communication Hwajung Lee Key Reference: Prof. Jong-Moon Chung’s Lecture Notes at Yonsei University

  2. Wireless Communications • Bluetooth • Wi-Fi • Mobile Communications • LTE • LTE-Advanced

  3. MobileCommunications Handover MobileCommunications Downlink&Uplink

  4. MobileCommunications Handover MobileCommunications Handover

  5. MobileCommunications Handover MobileCommunications Handover

  6. MobileCommunications Handover MobileCommunications Handover

  7. MobileCommunications Handover MobileCommunications Handover

  8. MobileCommunications Handover MobileCommunications Handover

  9. MobileCommunications Handover MobileCommunications Handover

  10. What is Cellular? (a) (b) (c) Possible Cell Arrangement

  11. To Overcome the Limited Frequency Band • Cellular Technology • Increase reusability by increase the number of cells • Multiple Access Technology • Allow multiple users to share a frequency band

  12. Types of Multiple Access Technology • FDMA (Frequency Division Multiple Access) • TDMA (Time Division Multiple Access) • CDMA (Code Division Multiple Access)

  13. FDMA, TDMA, and CDMA

  14. FDMA • Filter is needed at the receiver. • In a given frequency band • Large number of subchannels = Large number of users supported • Narrower subchannels  Low quality of sound & More interference • Closer subchannels  More interference • Due to interference, a guard band is necessary

  15. TDMA • Time slot, Time gate • IS-54 TDMA • In the US • Sets of 3 time slots in 30KHz • IS-136 TDMA • In the US • Sets of 6 time slots in 30KHz • GSM (Global System for Mobile) • In Europe • Sets of 8 time slots in 200KHz

  16. CDMA • Multiple signals in the same frequency band and in the same time slot. • Each signal uses a different code (i.e., a spread spectrum code) • Originally Spread Spectrum technology for a military use. • More secure against an eavesdropping • More resilient against a noise • The receiver, must know: • Spread spectrum code • The time the code was generated  Need to be synchronized • Currently use GPS (Global Positioning System)

  17. CDMA • Spread Spectrum • (ex) a signal with 10KHz  (125 times) 1.25MHz, a signal strength becomes a lot weaker. Like dropping a drop of ink in a water cup. Since the signal is extremely weak, it sounds like one of a noise  (advantage) • interference between signals will decrease. • Impact of a noise will affect to a small portion of the signal  improve the quality of sounds

  18. CDMA • White Noise (= Write Gaussian Noise) • Well-known noise  it can be eliminated using a filter • Spread Spectrum • Using PN Sequence (Pseudo random Noise Sequence) (ex) water in the water + a drop of ink example Original Signal (Analog)  Convert to a digital signal  XOR with PN Sequence  Modulated Analog signal • Receiver: Accept only the signal with the same PN sequence • i.e. the receiver can demodulate the CDMA signal which it knows the PN sequence. • Each communication pair uses a different PN Sequence

  19. CDMA: Spread Codes

  20. CDMA: Generation of a CDMA Signal

  21. CDMA: Example • User 1 • Data = 01 • Spread Code (PN Sequence) = 10101010 • CDMA Signal with XOR = • User 2 • Data = 11 • Spread Code (PN Sequence) = 00001111 • CDMA Signal with XOR = • User 3 • Data = 00 • Spread Code (PN Sequence) = 11001100 • CDMA Signal with XOR =

  22. CDMA: Combining CDMA Signals • Convert 1s and 0s to a digital signal • 1: -A pulse • 0: A pulse • Add • CDMA Signal of User 1 = • CDMA Signal of User 2 = • CDMA Signal of User 3 = • Combined Signal =

  23. CDMA: At the Receiver • Receiver of User 1 • Receive the combined signal = • Multiply the Spread Code (PN Sequence) to the received signal • PN Sequence of the User 1 = 10101010 • Recover the original signal from the User 1 =

  24. MobileCommunications • MobilePhoneEvolution • 1stGeneration(1G) • AMPS • 2nd Generation(2G) • GSM,IS-95(cdmaOne) • 3rd Generation(3G) • UMTS(WCDMA),CDMA2000 • 4th Generation(4G) • LTE-A

  25. List of Mobile Phone Generations

  26. AMPS • AdvancedMobilePhoneSystem(AMPS) • 1stGeneration(1G)mobilecellularphone • AnalogstandardusingFDMA(FrequencyDivisionMultiple Access) • DevelopedbyBellLabs • IntroducedinNorthAmericainOct.1983

  27. GSM GSM GlobalSystemforMobileCommunications(GSM) • 2nd Generation(2G)mobilecellularphone:Digitalsystem • IntroducedinFinlandin1991 • Dominantglobalstandard • Over90%marketshare • Operatedinover219countries&territories

  28. GSM GSM GlobalSystemforMobileCommunications(GSM) • GSMusesTDMA&FDMAcombined • TDMA(TimeDivisionMultipleAccess) • FDMA(FrequencyDivisionMultipleAccess)

  29. GSM GlobalSystemforMobileCommunication (GSM) • GSMsupportsvoicecallsanddatatransferspeedsupto9.6kbps,andSMS(Short MessageService)

  30. GSM GSM SIM (SubscriberIdentity Module) • SIMisadetachablesmartcard • SIMcontainsusersubscriptioninformationandphone book

  31. GSM GSM SIMAdvantages • SIMenablesausertomaintainuserinformationevenafter switchingcellularphones • Or,bychangingonesSIMausercanchangecellular phoneoperatorswhile usingthesamethemobilephone

  32. IS-95:cdmaOne • IS-95 • IS-95(InterimStandard95)isthefirstCDMAbased2Gdigitalcellularstandard • WhyCDMA? • CDMAperformswellagainst(narrow band) interferenceand(multipath)signalfading • cdmaOneisthebrandnameforIS-95that was developedbyQualcomm

  33. IS-95:cdmaOne • IS-95 • HutchisonlaunchedthefirstcommercialcdmaOne networkinHongKonginSeptember1995 • IS-95trafficchannelssupportvoiceordataatbitratesof upto14.4kbps

  34. UMTS • Universal MobileTelecommunicationsSystem (UMTS) • 3rd Generation(3G)mobilecellularsystem • EvolutionofGSM • UTRA(UMTSTerrestrialRadioAccess) supportsseveraldifferentterrestrialair interfaces

  35. UMTS • Universal MobileTelecommunicationsSystem (UMTS) • MultiuserAccessinUTRAcanbe supportedbyUTRA-FDDorUTRA-TDD • FDD(FrequencyDivisionDuplex) • TDD(TimeDivisionDuplex)

  36. UMTS:WCDMA • WCDMA(WidebandCodeDivision MultipleAccess) • 3rd Generation(3G)mobilecellularsystem thatusestheUTRA-FDDmode • 3GPP(3rdGenerationPartnershipProject) Release99 • Upto2Mbpsdatarate

  37. UMTS:WCDMA • WCDMA • FirstcommercialnetworkopenedinJapanis2001 • Seamless mobilityforvoiceandpacketdataapplications • QoS(QualityofService)differentiationforhighefficiency ofservicedelivery • Simultaneousvoiceanddatasupport • InterworkswithexistingGSMnetworks

  38. CDMA2000 • CDMA2000 • 3Gmobilecellularsystem • Standardizedby3GPP2 • EvolutionofIS-95cdmaOnestandards • UsesCDMA&TDMA • CDMA(CodeDivisionMultipleAccess) • TDMA(TimeDivision MultipleAccess)

  39. CDMA2000 • CDMA2000 • InitiallyusedinNorthAmericaandSouthKorea(RepublicofKorea)

  40. CDMA2000 • CDMA20001xEV-DO • CDMA20001xEV-DO(Evolution-DataOptimized) enables2.4Mbpsdatarate • CDMA20001xEV-DOnetworklaunchedinSouthKoreaonJanuary2002

  41. CDMA2000 • CDMA20001xEV-DO • Regardedasthefirst3GsystembasedonITU standards • ITU (InternationalTelecommunicationUnion) is thespecializedagencyforinformationandcommunicationtechnologyoftheUN (UnitedNations)

  42. HSDPA • High-SpeedDownlinkPacketAccess(HSDPA) • Enhanced3Gmobilecommunications protocol • EvolutionofUMTSforhigherdataspeeds andcapacity • BelongstotheHSPA(High-SpeedPacketAccess)familyofprotocols

  43. HSDPA • High-SpeedDownlinkPacketAccess(HSDPA) • HSDPAcommercialnetworksbecame availablein2005 • Peak DataRate • Downlink:14Mbps(Release5)

  44. EV-DORev.A • EV-DORev.A(RevisionA) • Peak DataRate • Downlink:3.1Mbps • Uplink:1.8Mbps • LaunchedintheUSAonOctober2006 • VoIPsupportbasedonlowlatencyandlow bitratecommunications

  45. EV-DORev.A • EV-DORev.A • EnhancedAccessChannelMAC • Decreasedconnectionestablishmenttime • Multi-UserPackettechnologyenablestheability formorethanoneusertosharethesametimeslot • QoS(QualityofService)flagsincluded forQoScontrol

  46. HSPA+ • EvolvedHigh-SpeedPacketAccess(HSPA+) • HSPA+allIPnetworkfirstlaunchedin HongKongin2009 • WCDMA(UMTS)based3Genhancement • HSPA+isaHSPAevolution

  47. HSPA+ • EvolvedHigh-SpeedPacketAccess(HSPA+) • Peak DataRate • Downlink:168Mbps • Uplink:22Mbps • MIMO(Multiple-Input&Multiple-Output)multiple-antenna techniqueapplied • WhyMIMO?MIMOusesuncorrelatedmultipleantennasbothatthetransmitterandreceiverto increasethedataratewhile usingthesamesignalbandwidthasasingleantennasystem.

  48. HSPA+ • EvolvedHigh-SpeedPacketAccess(HSPA+) • HigherDateRateAccomplishedby • MIMOmultiple-antennatechnique • Higherordermodulation(64QAM) • Dual-CellHSDPAisusedtocombine • multiplecellsinto one

  49. EV-DORev B • EV-DORev. B(RevisionB) • EV-DORev.Bwas firstdeployedinIndonesiaon January2010 • Multi-CarrierevolutionofRev.A • Higherdataratespercarrier • DownlinkPeak • 4.9 Mbpspercarrier • UplinkPeak • 1.8 Mbpspercarrier

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