Frequenies or ommuniaion wised pair oa able opial ransmission Mobile Communiaions Chaper : Wireless Transmission Frequenies Signals Anenna Signal propagaion Mulipleing Spread sperum Modulaion Cellular sysems Mm 300 H 0 km 30 kh 00 m 3 MH m 300 MH 0 mm 30 GH VLF LF MF HF VHF UHF SHF EHF inrared visible UV VLF = Very Low Frequeny ligh UHF = Ulra High Frequeny LF = Low Frequeny SHF = Super High Frequeny MF = Medium Frequeny EHF = Era High Frequeny HF = High Frequeny UV = Ulraviole Ligh VHF = Very High Frequeny Frequeny and wave lengh: λ = / wave lengh λ, speed o ligh 30 8 m/s, requeny 00 μm 3 TH μm 300 TH Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05. Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05. Frequenies or mobile ommuniaion VHF-/UHF-ranges or mobile radio simple, small anenna or ars deerminisi propagaion haraerisis, reliable onneions SHF and higher or direed radio links, saellie ommuniaion small anenna, beam orming large bandwidh available Wireless LANs use requenies in UHF o SHF range some sysems planned up o EHF limiaions due o absorpion by waer and oygen moleules (resonane requenies) weaher dependen ading, loss aused by heavy rainall e. Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.3 Frequenies and regulaions ITU-R holds auions or new requenies, manages requeny bands worldwide (WRC, World Radio Conerenes) Europe USA Japan Cellular Phones Cordless Phones Wireless LANs Ohers GSM 450-457, 479-486/460-467,489-496, 890-95/935-960, 70-785/805-880 UMTS (FDD) 90-980, 0-90 UMTS (TDD) 900-90, 00-05 CT+ 885-887, 930-93 CT 864-868 DECT 880-900 IEEE 80. 400-483 HIPERLAN 550-5350, 5470-575 RF-Conrol 7, 8, 48, 433, 868 AMPS, TDMA, CDMA 84-849, 869-894 TDMA, CDMA, GSM 850-90, 930-990 PACS 850-90, 930-990 PACS-UB 90-930 90-98 IEEE 80. 400-483 550-5350, 575-585 RF-Conrol 35, 95 PDC 80-86, 940-956, 49-465, 477-53 PHS 895-98 JCT 54-380 IEEE 80. 47-497 550-550 RF-Conrol 46, 868 Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.4
Signals I Fourier represenaion o periodi s physial represenaion o daa union o ime and loaion parameers: parameers represening he value o daa lassiiaion oninuous ime/disree ime oninuous values/disree values analog = oninuous ime and oninuous values digial = disree ime and disree values parameers o periodi s: period T, requeny =/T, ampliude A, phase shi ϕ sine wave as speial periodi or a arrier: s() = A sin( π + ϕ ) 0 g( ) = + n= a ideal periodi n sin(πn) + 0 n= b n os(πn) real omposiion (based on harmonis) Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.5 Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.6 Signals II Anennas: isoropi radiaor Dieren represenaions o s ampliude (ampliude domain) A [V] requeny sperum (requeny domain) phase sae diagram (ampliude M and phase ϕ in polar oordinaes) ϕ [s] A [V] [H] Q = M sin ϕ Composed s ranserred ino requeny domain using Fourier ransormaion Digial s need ininie requenies or pere ransmission modulaion wih a arrier requeny or ransmission (analog!) ϕ I= M os ϕ Radiaion and reepion o eleromagnei waves, oupling o wires o spae or radio ransmission Isoropi radiaor: equal radiaion in all direions (hree dimensional) - only a heoreial reerene anenna Real anennas always have direive ees (verially and/or horionally) Radiaion paern: measuremen o radiaion around an anenna y y ideal isoropi radiaor Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.7 Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.8
Anennas: simple dipoles Anennas: direed and seoried Real anennas are no isoropi radiaors bu, e.g., dipoles wih lenghs λ/4 on ar roos or λ/ as Herian dipole shape o anenna proporional o wavelengh Oen used or mirowave onneions or base saions or mobile phones (e.g., radio overage o a valley) y y λ/4 λ/ direed anenna Eample: Radiaion paern o a simple Herian dipole side view (y-plane) side view (y-plane) op view (-plane) y side view (y-plane) y side view (y-plane) Gain: maimum power in he direion o he main lobe ompared o he power o an isoropi radiaor (wih he same average power) op view (-plane) simple dipole op view, 3 seor op view, 6 seor seoried anenna Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.9 Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.0 Anennas: diversiy Signal propagaion ranges Grouping o or more anennas muli-elemen anenna arrays Anenna diversiy swihed diversiy, seleion diversiy reeiver hooses anenna wih larges oupu diversiy ombining ombine oupu power o produe gain ophasing needed o avoid anellaion λ/4 λ/ + λ/4 λ/ λ/ + λ/ Transmission range ommuniaion possible low error rae Deeion range deeion o he possible no ommuniaion possible Inererene range may no be deeed adds o he bakground noise sender ransmission deeion inererene disane ground plane Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05. Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.
Signal propagaion Real world eample Propagaion in ree spae always like ligh (sraigh line) Reeiving power proporional o /d² in vauum muh more in real environmens (d = disane beween sender and reeiver) Reeiving power addiionally inluened by ading (requeny dependen) shadowing releion a large obsales reraion depending on he densiy o a medium saering a small obsales diraion a edges shadowing releion reraion saering diraion Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.3 Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.4 Mulipah propagaion Signal an ake many dieren pahs beween sender and reeiver due o releion, saering, diraion a sender Time dispersion: is dispersed over ime mulipah LOS pulses pulses (Line o Sigh) a reeiver inererene wih neighbor symbols, Iner Symbol Inererene (ISI) The reahes a reeiver direly and phase shied disored depending on he phases o he dieren pars Ees o mobiliy Channel haraerisis hange over ime and loaion pahs hange dieren delay variaions o dieren pars dieren phases o pars quik hanges in he power reeived (shor erm ading) power Addiional hanges in disane o sender obsales urher away slow hanges in he average power reeived (long erm ading) long erm ading shor erm ading Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.5 Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.6
Mulipleing hannels k i Frequeny muliple Mulipleing in 4 dimensions spae (s i ) ime () requeny () ode () Goal: muliple use o a shared medium s k k k 3 k 4 k 5 k 6 s Separaion o he whole sperum ino smaller requeny bands A hannel ges a erain band o he sperum or he whole ime Advanages: no dynami oordinaion neessary works also or analog s k k k 3 k 4 k 5 k 6 Disadvanages: Imporan: guard spaes needed! wase o bandwidh i he rai is disribued unevenly inleible s 3 guard spaes Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.7 Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.8 Time muliple Time and requeny muliple A hannel ges he whole sperum or a erain amoun o ime Advanages: Combinaion o boh mehods A hannel ges a erain requeny band or a erain amoun o ime Eample: GSM only one arrier in he medium a any ime hroughpu high even or many users Disadvanages: preise synhroniaion neessary k k k 3 k 4 k 5 k 6 Advanages: beer proeion agains apping proeion agains requeny seleive inererene higher daa raes ompared o ode muliple bu: preise oordinaion required k k k 3 k 4 k 5 k 6 Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.9 Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.0
Code muliple Modulaion Eah hannel has a unique ode All hannels use he same sperum a he same ime Advanages: bandwidh eiien no oordinaion and synhroniaion neessary good proeion agains inererene and apping Disadvanages: lower user daa raes more omple regeneraion Implemened using spread sperum ehnology k k k 3 k 4 k 5 k 6 Digial modulaion digial daa is ranslaed ino an analog (baseband) ASK, FSK, PSK - main ous in his haper dierenes in speral eiieny, power eiieny, robusness Analog modulaion shis ener requeny o baseband up o he radio arrier Moivaion smaller anennas (e.g., λ/4) Frequeny Division Mulipleing medium haraerisis Basi shemes Ampliude Modulaion (AM) Frequeny Modulaion (FM) Phase Modulaion (PM) Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05. Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05. Modulaion and demodulaion analog baseband digial daa digial analog 0000 modulaion modulaion radio ransmier analog demodulaion radio arrier analog baseband radio arrier synhroniaion deision digial daa 0000 radio reeiver Digial modulaion Modulaion o digial s known as Shi Keying Ampliude Shi Keying (ASK): very simple low bandwidh requiremens 0 very susepible o inererene Frequeny Shi Keying (FSK): needs larger bandwidh Phase Shi Keying (PSK): more omple robus agains inererene 0 0 Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.3 Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.4
Advaned Frequeny Shi Keying Eample o MSK bandwidh needed or FSK depends on he disane beween he arrier requenies speial pre-ompuaion avoids sudden phase shis MSK (Minimum Shi Keying) bi separaed ino even and odd bis, he duraion o eah bi is doubled depending on he bi values (even, odd) he higher or lower requeny, original or invered is hosen he requeny o one arrier is wie he requeny o he oher Equivalen o ose QPSK daa even bis odd bis low requeny high requeny 0 0 0 bi even 0 0 odd 0 0 h n n h value - - + + h: high requeny n: low requeny +: original -: invered even higher bandwidh eiieny using a Gaussian low-pass iler GMSK (Gaussian MSK), used in GSM MSK No phase shis! Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.5 Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.6 Advaned Phase Shi Keying Quadraure Ampliude Modulaion BPSK (Binary Phase Shi Keying): bi value 0: sine wave bi value : invered sine wave very simple PSK low speral eiieny robus, used e.g. in saellie sysems QPSK (Quadraure Phase Shi Keying): bis oded as one symbol symbol deermines shi o sine wave needs less bandwidh ompared o BPSK more omple Oen also ransmission o relaive, no absolue phase shi: DQPSK - Dierenial QPSK (IS-36, PHS) A Q I 0 0 Q I 00 0 0 00 0 Quadraure Ampliude Modulaion (QAM): ombines ampliude and phase modulaion i is possible o ode n bis using one symbol n disree levels, n= idenial o QPSK bi error rae inreases wih n, bu less errors ompared o omparable PSK shemes Q 000 00 a φ 000 Eample: 6-QAM (4 bis = symbol) 0000 Symbols 00 and 000 have he same phase φ, bu dieren ampliude a. 0000 and 000 have I dieren phase, bu same ampliude. 000 used in sandard 9600 bi/s modems Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.7 Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.8
Hierarhial Modulaion DVB-T modulaes wo separae daa sreams ono a single DVB-T sream High Prioriy (HP) embedded wihin a Low Prioriy (LP) sream Muli arrier sysem, abou 000 or 8000 arriers QPSK, 6 QAM, 64QAM Q Eample: 64QAM good reepion: resolve he enire 64QAM onsellaion poor reepion, mobile reepion: 0 resolve only QPSK porion I 6 bi per QAM symbol, mos signiian deermine QPSK HP servie oded in QPSK ( bi), LP uses remaining 4 bi 00 00000 000 Spread sperum ehnology Problem o radio ransmission: requeny dependen ading an wipe ou narrow band s or duraion o he inererene Soluion: spread he narrow band ino a broad band using a speial ode proeion agains narrow band inererene power inererene Side ees: spread power deeion a reeiver proeion agains narrowband inererene oeisene o several s wihou dynami oordinaion ap-proo Alernaives: Dire Sequene, Frequeny Hopping spread inererene Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.9 Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.30 Ees o spreading and inererene Spreading and requeny seleive ading dp/d dp/d hannel qualiy i) iii) dp/d ii) sender iv) dp/d user broadband inererene narrowband inererene v) dp/d narrow band hannel qualiy 3 4 guard spae 5 6 requeny narrowband hannels spread sperum hannels reeiver spread sperum requeny Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.3 Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.3
DSSS (Dire Sequene Spread Sperum) I XOR o he wih pseudo-random number (hipping sequene) many hips per bi (e.g., 8) resul in higher bandwidh o he Advanages redues requeny seleive ading in ellular neworks base saions an use he same requeny range several base saions an dee and reover he so handover Disadvanages preise power onrol neessary 0 0 0 0 0 0 0 0 0 0 0 0 0 0 b : bi period : hip period Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.33 b user daa XOR hipping sequene = resuling DSSS (Dire Sequene Spread Sperum) II reeived user daa radio arrier hipping sequene demodulaor X reeiver spread sperum ransmier lowpass ilered hipping sequene radio arrier modulaor ransmi Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.34 X orrelaor produs inegraor sampled sums deision daa FHSS (Frequeny Hopping Spread Sperum) I FHSS (Frequeny Hopping Spread Sperum) II Disree hanges o arrier requeny sequene o requeny hanges deermined via pseudo random number sequene Two versions Fas Hopping: several requenies per user bi Slow Hopping: several user bis per requeny Advanages requeny seleive ading and inererene limied o shor period simple implemenaion uses only small porion o sperum a any ime Disadvanages no as robus as DSSS simpler o dee b 0 0 d d b : bi period d : dwell ime user daa slow hopping (3 bis/hop) as hopping (3 hops/bi) Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.35 Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.36
FHSS (Frequeny Hopping Spread Sperum) III Cell sruure user daa modulaor narrowband modulaor spread ransmi Implemens spae division muliple: base saion overs a erain ransmission area (ell) Mobile saions ommuniae only via he base saion hopping sequene reeived ransmier demodulaor requeny synhesier narrowband requeny synhesier demodulaor daa hopping sequene reeiver Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.37 Advanages o ell sruures: higher apaiy, higher number o users less ransmission power needed more robus, deenralied base saion deals wih inererene, ransmission area e. loally Problems: ied nework needed or he base saions handover (hanging rom one ell o anoher) neessary inererene wih oher ells Cell sies rom some 00 m in iies o, e.g., 35 km on he ounry side (GSM) - even less or higher requenies Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.38 Frequeny planning I Frequeny planning II Frequeny reuse only wih a erain disane beween he base saions Sandard model using 7 requenies: 3 4 5 6 4 5 3 ell luser 4 5 6 7 4 5 7 Fied requeny assignmen: erain requenies are assigned o a erain ell problem: dieren rai load in dieren ells Dynami requeny assignmen: base saion hooses requenies depending on he requenies already used in neighbor ells more apaiy in ells wih more rai assignmen an also be based on inererene measuremens 7 h h h 3 h h h 3 g g g 3 g g g 3 g g g 3 3 ell luser wih 3 seor anennas 6 5 7 ell luser Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.39 Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.40
Cell breahing CDM sysems: ell sie depends on urren load Addiional rai appears as noise o oher users I he noise level is oo high users drop ou o ells Pro. Dr.-Ing. Johen Shiller, hp://www.johenshiller.de/ MC SS05.4