Ch04-1

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? ? ? ? ? ?

• ???? Modulation
• ??? ?? jerry_at_mail.yust.edu.tw

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????(BaseBand)

• ???????(10BaseTx)???????????????10Mbps?????(BaseBa
  nd)??Manchester Coding????,Manchester?????????????
  ????????????????(Carrier),???????????10BaseTx?Base
  ???BaseBand?

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?????? Carrier System

• ??????????????? Modulate ?????
• Amplitude Modulation, AM???????????
• Frequency Modulation, FM??????
• Phase Modulation, PM??????
• Quadratune Amplitude Modulation, QAM????????????
• ???????????,???sin()?cos()???????????????????

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????

• Digital Modulation

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?????? Carrier System
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???? Carrier System

• CODEC?coder (???)?decoder(???)????
• MODEM?Modulator(???)?Demodulator(???)????
• ????? 20Hz4kHz,??8kHz 8bits????(Sampling)???????,
  ?????????64kbps??????????
• ??????(Ethernet)????10Mbps?????(baseband)?????????
  ????,?????????

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Shift Keying

• ASK(Amplitude Shift Keying)?????????????
• FSK(Frequency Shift Keying)?????????????
• PSK(Phase Shift Keying)?????????????Binary????Leve
  l????

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Shift Keying
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?????? Pulse Carrier System
???? ???????????? Pulse-amplitude modulation
(PAM) ??????????????? ????????(PBX private
Branch exchange) Pulse-duration modulation
(PDM) ????????????????? ????????(PBX private
Branch exchange) Pulse-position modulation (PPM)
?????????????????
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??

• ????????????????????????????????
• ???????????????????,?????????IQ???,????????,??????
  ????????????,??????,???????????????
• ?????????????

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IQ???(I-Q Constellation)

• ?IQ Modulator????,????????Polar
  Diagram(????)????????????,?????????????

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(No Transcript)
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• ?Polar Diagram??,?????????????????????????????????
  ?????,???????1 Hz,?????????

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(No Transcript)
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• ??????????????????,??????????90???????????????,???
  ??????(??3.16)?????Polar Diagram???I-Q
  Diagram(???I-Q Cons-tellation),??????????????,???
  ??????A(Amplitutde)???I??Q??I?ACos(?),Q?ASin(?)?
  ?????A(Amplitutde)??????X??Y??

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(No Transcript)
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• ??????????????????????????????,???????????????????
  ,????I??Q??

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(No Transcript)
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??I-Q Diagram??BPSK,???????Bit ?Input Data???
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• ??I-Q Diagram??QPSK,???3.18????????Bit?Input
  Data????QPSK???0??90??180???270??????????Polar
  Diagram??,45/135/225/315??0/90/180/270?????,??????
  ??????I-Q Modulation??,??????????????I-??Q-??

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(No Transcript)
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• M-ary PSK??Multiple Lavel PSK,??3.19?8-PSK?M-PSK??
  ????????,???????,??Phase Detecter????QAM??I?Q?????
  ??,Phase Detecter???????Phase?????QAM????I-Q
  Modulator?Modulate?Demodulate?

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(No Transcript)
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• M-ary QAM??Multiple Lavel?QAM,??3.20?16-QAM????16-
  QAM?????I????Q?,??IQ Modulator??????????Polar
  Diagram??,???12?,?A(Amplitude)?3??????15???!?????3
  2-QAM??36-QAM???????????802.11a?48Mbps?54Mbps???64
  -QAM?????????512QAM?1024-QAM???802.16??????2048-QA
  M???????QAM,??Channel???????

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(No Transcript)
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FSK???

• ??????????,FSK?????,?MSK?GMSK?FSK??????,??930MHz??
  ???????????930.000MHz?930.008MHz???3.21?A????????,
  ????????B?C?(??I???)???MSK??,?????,???????????,???
  ?????IQ Modulator????Trajectory????,????????????,?
  ?Channel?????????????QPSK?Trajectory??????,?????QP
  SK?????Trajectory??Symbol???????????????

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(No Transcript)
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• ???????,??????????,?????????????????,?????????,???
  ???,????????????????,??????????????,??????????????
  ,?????????,???????????

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(No Transcript)
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QPSK???

• ??????????,QPSK??????,?OQPSK?p/4
  DQPSK?QPSK?????????????,??????????????????????????
  ?????????Trajectory????,????QPSK??????Offset QPSK
  (OQPSK)?I?Q????????????3.23?A????Q,????Bit-Time??,
  ???????I?????B??C?,?I?????????????,????State??B???
  ??Bit-Time??,?Q???,????A??

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(No Transcript)
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• ??????QPSK IQ?????????????????p/4
  DQPSK?????????p/4?QPSK???,??????????????????3.24,?
  ????A?,???????Bit??????E/F/G/H??????????p/4???????
  ????p/4?D?Differential,??????????????????

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(No Transcript)
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?????

• ?3.25?????????????????????????Channel(??Air
  Path),?????????????White Noise????????????????????
  ???,???????????????????White Noise??????,?VCO?????
  ??(Phase Jitter)??????,?802.11a???Training
  Sequence?Pilot Tone???????????

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(No Transcript)
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?????????

• ????(Bandwidth Efficiency)?????(Spectrum
  Efficiency)???????????,?????????????????,?????????
  ?????Time Domain??????????Frequency
  Domain??????,?????bit/sec/Hz???Shannon-Hartley?Cap
  acity Theorem,?????????????3.26?Fb?Data
  Rate,W?Channel???,??802.11b?Channel???22MHz?Fb/W??
  ?????Hz?????Bit?????????,??????????,????????????

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(No Transcript)
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• ?Eb/No??,????????,??????,????????64-QAM?16-QAM?8-P
  SK????????,?????Eb/No???????OFDM??,M????(Sub-Carri
  er)???,?802.11a?48??M??,??????????,???????Symbole
  Rate?????Eb/No???,???????????8-DPSK?8-PSK,?????Eb/
  No,???DPSK???????????,????????Symbol???,??????????
  ?????,?DPSK?PSK?????????

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(No Transcript)
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• ?3.28????????????????????,???????3.27???

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?3.28????????????????????,???????3.27???
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• ??3.29,GSM???????GMSK,???MSK?BFSK??,?Bandwidth
  Efficiency?????1 bit/sec/Hz????????????????Spectru
  m??????25,???Spectral Efficiency????1/3?NADC???QP
  SK,Spectral Efficiency????2,??Spectral
  Efficiency??1.6?802.11g???Spectral
  Efficiency??2.7,??LMDS?????7,????????????,

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(No Transcript)
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OFDM Modulation?Multiplexing???? OFDM?????

• 802.11g??????OFDM,??802.11a????OFDM,?????????,????
  ?????802.11g?OFDM?Multiplexing??,???????Modulation
  ???802.11g???????????BPSK?QPSK?16-QAM??64-QAM?????
  ???????,???IQ-Plane(??IQ Constellation)????????,??
  ??

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(No Transcript)
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• ???,???ez???????????(1),??z?j???????(2)????(2)????
  ,??cos()?sin()???????,?????Herr Leonard
  Euler???????????????,???Euler???????????????????,?
  ????ej2pft??RF????ej2pft?cos()????I?,ej2pft?sin()?
  ???Q???????RF????ej2pft???

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(No Transcript)
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• ????????????,???????????RF?,?????2.4GHz,????12????
  ????????????,????A???????45????????12??,????????,?
  ?????????1Hz???RF????,?? ????f1????,???f2??f1?????
  ?f1????,????f2??f1???,??3.32????????????????????

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(No Transcript)
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• ??????90?,??????0.25Hz,????(j),??ej(p/4),cos(p/4)
  jsin(p/4)0j???IQ-Plane??????j??????0.25Hz???5
  ??90?,??5j?????RF?,??,??????f2???f3f1f2?,?????
  ???????,???????f2???

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(No Transcript)
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• ???????????,?????RF???Complex Exponential?????????
  ??????Complex Exponential??,??????????????????????
  ????f1-f2??!
• ?????????????????????????????

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(No Transcript)
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• ?????????????,???cos(2pf0t)??????????????,???sin(2
  pf0t)??????????????,????????????(???????)?????????
  ????????????3.35,????IQ-Plane???????Euler???????Eu
  ler?????????,???????????sin()?cos()?

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(No Transcript)
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• ?????????,????Euler????????????Euler
  cos()??,??Euler sin()????????????IQ-Plane?????????
  ????????????Cos()?,????1/2????????????,???????????
  ???????????????sin()???????????IQ-Plane??????Euler
  ????

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(No Transcript)
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• ???????????,????????Euler??????????????Euler??????
  ???????sin()??,?????????????????j,?????????????j,?
  ?????

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• ??????,??????IQ-Plane??????,?????cos()?sin()????co
  s()??????????????????sin()????????????????????????
  ?0.5??????

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(No Transcript)
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• ??sin()?????,?jsin()????IQ-Plane??????90?????cos(
  )???Euler????,?????????,??????????????????!

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(No Transcript)
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• Ns????????,fc???????dins/2???i?????QAM?(??IQ-Plan
  e???)???802.11a??????,?fc?5.18GHz,??ts lt t
  lttsT?T?Symbol???,??3.2µs,????????????????1/T,??31
  2.5KHz??Ns?64,??????64????????????????48????,??4?T
  raining????????????????,??12????????dins/2???,???
  ??????

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(No Transcript)
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(No Transcript)
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• ?????,?????,??????,??????????,?????????????Time
  Domain?????????????????????????????????

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(No Transcript)
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• ?????????????,??????????????????????????????,?????
  ?????????????????,?????????,??sinc()?????

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(No Transcript)
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• ?????????,?????T?Time-Domain???????,?????????????f
  c??????Frequency-Domain???sinc()??????fc???1/T??,?
  ???????fc??????,??802.11g??2.4GHz
  ISM??,?802.11a??5GHz UNII?????Time
  Domain?????,??????????????????????????????

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(No Transcript)
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• ????????????1/T,???????????,??????????????????????
  ?????????,???????????????

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(No Transcript)
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• ???????sinc()?????,???sinc(x)??,???fc???,?1/T??p??
  ??Frequency????,fc?????,??????????3.42?,t0???????
  ???
• ?OFDM?64?????,????????????12????????????????,?????
  ???????????????????????????????????I??Q??????

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(No Transcript)
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(No Transcript)
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• sinc(x)???,?x -gt 0?,??sinc(x)1???????????????

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(No Transcript)
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• 64-QAM??????????6?Bit???OFDM????Coding?????Forward
  Error Correction,?????????Bit????,???????Coding??
  ?????Redundant Bit?????Bit,?3/4Coding
  Rate????????Bit??????Bit??????????Symbol?Frequency
  ?Phase???????????????????I??Q??

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(No Transcript)
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OFDM????

• OFDM?Transceiver(????OFDM Modem)????BaseBand?RF???
  ,OFDM???????BaseBand?

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(No Transcript)
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??

• ????LAN???????WLAN,???802.11bag?IEEE
  ?????????,????????IQ-Diagram???IQ-Diagram??????,??
  ????????????
• ???????????,??????????????????,????????????????(Di
  gital Signal Processing)??????????????????????????
  ??????????????,????????????????,????????????