System Theory and Technologies. What means the Nyquist Criterium for baseband transmission?

Transcription

1 Chapter 3 System Theory an Tehnologies 1 Exerise What means the Nyquist Criterium or baseban transmission? What is the avantage / isavantage o a Manhester-Coe ompare to the AMI Coe? A rame with 1000 Bit is transmitte using a bit rate o 100 Mbit/s between sener an reeiver. They are onnee with a 100m long able. Estimate the time rom start o the rame until the rame is reeive on the reeiver? 1

2 Enoing: 4B/5B 3 MLT3 - Coierung 4

3 r... How to transport igital symbols...? Introution 3.1. Symbols, Bits an Bau Wire Physial Layers Raio base physial layer eletromagneti waves Moulation Optial physial layer 5 Eletromagni waves (1) Antenna: transormation voltage/urrent-> EM-iel Transmitter Raio-Channel Antenna: transormation EM-iel -> voltage/urrent Reeiver 6 Emitting requeny: wavelength: spee: polarization power [Bm] beam epens on - Transmitter - Antenna λ Channel multipath -> intererene - onstrutive - estrutive (aing) loss o power - absorption - reletion epens on - requeny - environment Reeiving epens - antenna - sensitivity - power o EM-Fiel 3

4 4 Eletromagneti waves () r z Θ Θ P io x y Φ L + Θ = t j j L i E r ω ω πε exp 1 ) os( = 0 = = Θ Φ H H E r Θ = Θ t j j j L i E ω ω ω πε exp 4 ) sin( Θ = Φ t j j L i H ω ω π exp 4 ) sin( 0 Ieal raio-hannel S E P T l G TA G RA P R T T R RA TA T R 4 G G l P P = π λ Transmission Ratio 8 G Antenna Gain (G Bi = 10 Bi. lg G) λ = 0 / wavelenght ( 0 = km/s) Loss: = Inverse Transmission Ratio Soure: Uwe Meier

5 Free Spae Propagation Free Spae propagation P ( l) Pt Gt G (4π ) l r = L: System loss ator >1, L=1: no loss in HW System G: Antenna gain r λ L 9 Isotropi raiator: ieal antenna whih raiate power uniormly in all iretions. Eetive isotropi raiate power(eirp): EIRP = P t G t Eetive raiate power (ERP): Maximum raiate power as ompare to λ/ ipol antenna Dipol: gain 1.64 (.15 B) above an isotropi antenna ERP.15 B smaller than EIRP Ieal Raio Channel 100,00 TS P T G TA l G RA P R ER 90,00 80,00 nkämpung in B Fun 70,00 60,00 50,00 5,8 GHz 40,00,44 GHz 869 MHz 30, MHz 0, S-E-Abstan in m 10 Antennq Gain: G TA = G RA = Bi = 1,58 Soure: Uwe Meier 5

6 Path loss PL [ B ] Pt 10log P r Gt G = 10log (4π ) λ l r = PR P B l GTA G = 9,4 0lg 0lg + + km GHz Bi Bi / T RA Far-iel: l >: D ; >> D; λ = >> λ 11 D: largest physial linear imension o antenna Path loss lose-in istane 0: known reeive power reerene point l >l0 > Typial values or 1-GHz 1m (inoor) 100m or 1000m (outoor) P l0 r ( l) = Pr ( l 0) l Pr ( l0) l0 Pr [ Bm] = 10log + 0log 0.001W l 1 6

7 Real Raio-Channel T Diret Wave relete Wave R LOS iration Obstale shaow reration R NLOS Shaow-bounary LOS: Line o sight 13 NLOS: Non line o sight Soure: Uwe Meier Multipath (Sattering) 14 7

8 Doppler-Shit π Δl ΔΦ = λ π v Δt = os( Θ) λ = 1 π Φ = t 1 π ΔΦ Δt v = os( Θ) λ x Δl v y 15 Path loss Reletion Objet with large imensions ompare to wavelength Groun reletion Builings... Diration Bye surae with sharp irregularities (eges) Reration Wave passes ierent materials Sattering Meium has elements small ompare to wavelength Number o Obstales/Volume is large Consequene: epens on the environment-> omplex moels or estimation 16 8

9 Faing Rapi hanges in signal strength over a small travel istane or time interval Ranom Frequeny moulation ue to varying Doppler shits on ierent multipath signals Time ispersion (eho's) ause by multipath propagation elays Inluene by Multipath propagation o Spee o mobile Spee o surrouning Objets Transmission banwith o the signal 17 Real raio hannel (reeive power) 5,8-GHz-hannel (outoor, Sinussignal) LOS Empangsleistung in Bm Zeit in Sek. NLOS time-seletive aing (movements) 18 Soure: Uwe Meier 9

10 Real raio hannel,4-ghz-hannel (inoor, transmission ratio in B) no reletions reletions (LOS) ISM x 10 9 requeny seletive aing (multiple path) ISM , GHz 1, GHz x Soure: Uwe Meier Real raio hannel Reeive power in a ity builings sener 0 Soure: Uwe Meier 10

11 Real raio hannel Reeive power in a ity 434 MHz,44 GHz Depens on the requeny 1 Soure: Uwe Meier Inormation 0 Banwith[Hz] Frequeny [Hz] transmission o inormation nees banwith more banwith -> more inormation/time Higher requenies, bigger banwith easier available 11

12 ISM-Bans: Inustrial-Sientii-Meial No ee s Can be use all over the worl, but there are some restritions uty yle maximum power Dierent requeny-bans available Moulation, protools or servies as preerre Cheap beause o mass-market 3 Warm Up! What is MLT3-Coing? What is aing? What are reasons? What are the problems? Using a mobile phone working at 900 MHz in a ar or a high spee train will lea to requeny-shits ue to the oppler eet. Estimate t the possible requeny-shit (spee: 00 km/h) 4 1

13 ISM-Ban s only EU iv. Anwen. Hz 868 M WLAN Bluetooth ZigBee Nanonet Frequenz WLAN HiperLAN 5,1 GH Hz MHz only EU iv. Anwen. 5 MHz 91 only USA iv. Anwen.,4 4 GHz,,7 GHz 5, WLAN HiperLAN 5 Frequeny alloation Germany 6, ,83 MHz ISM 40, , 7 MHz ISM 433, ,79 MHz ISM MHz ISM (ZigBee) MHz GSM-D (seit 199) 1, ,88 GHz GSM-E = DCS 1800 (seit 1994) 1, ,99 GHz DECT 1,885...,05 GHz;,1..., GHz UMTS,4...,4835 GHz ISM (WLAN, Bluetooth, ZigBee,...) 5, ,875 GHz ISM (WLAN) ,5 GHz ISM ISM inustrial, sientii, meial GSM global system or mobiles DECT igital European orless teleommuniations UMTS universal mobile teleommuniation system 6 13

14 Moulation Transormation o a igital (binary) base ban-signal into another requeny-range Moulation o an harmoni arrier hange amplitue hange phase hange requeny eah kin o moulation nees banwith ommuniation oten is haraterize by the requeny o the arrier Baseban binary Moulator Booster antenna moulate RF 7 Harmoni arrier igital moulation 1 Bit 1 Symbol Moulator Demoulator uniirektional, simplex Transeiver Transeiver biirektional, uplex 8 14

15 basis: base ban-transmission Bit 1 TB Base ban t [s] Bit 0 Bit rate: 1/TB [Bit/s] Nyquist banwith: N=1/TB [Hz] banwith N [Hz] 9 ASK: Amplitue Shit Keying Bit 1 Bit 0 TB t [s] moulate arrier Bit rate: 1/TB [Bit/s] banwith: N-H=1/TB [Hz] TP -> T=1/Tp Banwith T [Hz] 30 Matlab 15

16 PSK: Phase Shit Keying Sequene o bits moulate signal time t/t im os (Phase= 180 ) 1 os (Phase= 0 ) re Matlab FSK: Frequeny Shit Keying Sequene o bits 0 = A + B moulate signal Δ = B A 3 Δ A 0 B 0 1 time t/t μ = Δ r Δ = 1 Matlab 16

17 4-PSK / QAM 00 a im 10 im -a a re re 01 -a 11 4-PSK bits -> 1 o 4 symbols 16 QAM 4 bits -> 1 o 16 symbols 33 more bits buil one symbol! Matlab Deinition o Sprea Spetrum (SS) A transmission tehnique in whih a Pseuonoise oe (inepenent o the inormation ata) is employe a moulation waveorm o sprea sprea the signal energy over a banwith muh greater than signal inormation Banwith. At a reeiver the signal is esprea using a synhronize replia o o the Pseuo-noise oe 34 17

18 History/Bakgroun Introue uring seon worl war Dominate long time military ommuniation appliations 1980 irst ommerial appliations Use in 3G ellular systems Use in.4 GHz ISM-Ban, beause this was a onition 35 DSSS priniple (1) T S T C tx Binary ata X Moulator -PSK pn t PN-Coe Baseban RF ~ banpass 36 oherent emoulation 18

19 DSSS priniple () Short oe system: PN-Coe uration equal to a ata symbol uration symbol t N T pn t t pn t 37 DSSS priniple (3) Long oe system PN oe length muh longer than a ata symbol symbol t N T pn t t pn t 38 19

20 DSSS: Properties o spetrum T RF -R RF W SS instantaneously: broaban RF + R 39 FHSS priniple (1) Binary ata Moulator -FSK Mixer X Ban pass tx arrier Base ban ~ Frequeny Synthesizer PN-Coe pn t /n ban pass 40 n: Deines hopping rate no oherent emoulation 0

21 FHSS priniple () ast hopping PN-Coe uration equal to a ata symbol uration (or shorter) symbol T T Hop FHSS priniple (3) Slow hopping PN-Coe equal to a ata symbol symbol T Hop

22 FHSS: Properties o spetrum hop T hannel N D Ch RF W SS = N. D Ch instantaneously: smallban on average: broaban 43 DSSS priniple t rx b tx b tx rx r X Moulator Demoulator X hannel pn r pn t RF PN ~ ~ RF PN Coe Coe Base ban -R s T S R S ban pass t T S T C Base ban 44 T R S -R C R C

23 Intererene t X tx b + Intererene i rx b X r pn t pn r PN Coe hannel PN Coe 45 Intererene (Narrowban) t X pn t PN Coe tx b T S Data-signal + hannel Intererene i whitene intererene R S narrowban -R s R S intererene DS-signal (sprea) R T S -R C R C rx b T S X PN Coe r pn r DS-signal (e-sprea) R C 46 3

24 Intererene (Broaban) t X pn t PN Coe tx b T S Data-signal + hannel Intererene i whitene intererene R S broaban -R s R S DS-signal intererene (sprea) R T S -R C R C rx b T S X PN Coe r pn r DS-signal (e-sprea) R C 47 Intererene (Gaussian noise) t X pn t PN Coe tx b T S Data-signal + hannel Intererene i whitene Gaussian noise -R R s S -R R s S DS-signal (sprea) gaussian noise T -R C R C rx b T S X PN Coe r pn r DS-signal (esprea) R C 48 4