Mvr - Analog Links

7/24/2019 Mvr - Analog Links

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M.V. RAGHUNADHAssociate Professor, Dept. of ECE

NIT, Warangal !"#""$.

rag%&'nit(.ac.in

)IN*+

ANA)G


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Elements of an optical communication system


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-ig. /01 2asic ele3ents

an4 3a5or Noise contri6&tors in an analog lin7

- A48antageo&s to trans3it infor3ation in its-

original analog for3at- E91/ / M&ltiple9e4 Micro(a8e signals

/ H:6ri4 fi6er;coa9 s&6scri6er ser8ices

/ Vi4eo 4istri6&tion

/ Ra4io o8er -i6er


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3ost fi6er optic s:ste3s are i3ple3ente4 4igitall:

Certain applications re 4istri6&tion- 3icro(a8e lin7s s&c% as connections 6et(een

re3otel: locate4 antennas an4 6ase stations.


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Main para3eters are/// CNR, 2an4(i4t%, +-DR,

+ignal 4istortion fro3 nonlinearities +&6 Carrier Mo4&lation =+CM>

/ 2ase6an4 signals are first s&peri3pose4 onR- s&6carriers

/ R- s&6carriers are co36ine4 &sing -DM in

electrical 4o3ain

/ Res&lting electrical signal is 3o4&late4 onto

optical carrier

E91/ # MH? 8i4eo signals in CATV s:ste3s

R- o8er -i6er / Trans3itting 3icro(a8e analog signals in

t%e range ".@ to @"" GH? o8er a fi6er lin7

for 4istri6&ting 6roa46an4 3icro(a8e signals

in 6roa46an4 (ireless co33&nication nets


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Trans3itter &ses )ED or )aser 4io4e as so&rce 2ias point is set at t%e 3i4point of linear portion Analog signal is sent &sing 3o4&lation sc%e3es

Direct Intensit: Mo4&lation=IM>

/ optical so&rce o&tp&t is 3o4&late4 si3pl: 6:

8ar:ing t%e c&rrent aro&n4 t%e 6ias point inproportion to t%e 3essage signal

+&6 Carrier Mo4&lation =+CM>

/ co3ple9 6&t 3ore efficient 3et%o4/ +&peri3pose 6ase6an4 signal onto electrical

s&6carrier =6: -DM> prior to intensit:

3o4&lation of t%e optical so&rce &sing AM,-


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-i6er s%all %a8e flat a3plit&4e an4 gro&p 4ela:

Response (it%in t%e pass6an4

+ingle Mo4e fi6er is c%osen as t%e 3o4el

4istortion li3ite4 6an4(i4t% is 4iffic&lt to e

ptical recei8er i3pair3ents are APD gain noise,

an4 T%er3al noise


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Carrier/to/noise ratio =CNR>

Analog s:ste3 &ses a carrier-to-noise ratio analysis

instea4 of a signal/to/noise ratio anal:sis,

since t%e infor3ation signal nor3all: is s&peri3pose4 on

a ra4io/fre carrier t%ro&g% an optical intensit:

3o4&lation sc%e3e.

It is ratio of r3s carrier po(er to t%e r3s noise po(er at

t%e inp&t of t%e R- recei8er follo(ing t%e p%oto4etector.

-+*/ 2ER of 0"/ translates to a CNR of @# =0!.# 42> 2ER of 0"/0!translates to a CNR of #$ =0." 42>

AM/ 2ER of 0"/ translates to a CNR of !# 42

-M/ 2ER of 0"/ translates to a CNR of 0!/0 42


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Analog Transmission System

In photonic analog transmission

system the performance of the

system is mainly determined bysignal-to-noise ratio at the output of

the receiver.

In case of amplitude modulation the

transmitted optical power P(t)is in

the form of:

where mis modulation index and

s(t)is analog modulation signal.

The photocurrent at receiver can be

expressed as:

[7-13]

Analog !E" modulation

)](1[)( tmsPtP t += BI

Im

=

)](1[)( 0 tmsMPti rs +=


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CARRIER PWER1

To fin4 carrier po(er, first t%e generate4 analog signal.

t%e 4ri8e c&rrent t%ro&g% t%e optical so&rce is t%e s&3 of

a fi9e4 6ias c&rrent an4 a ti3e/8ar:ing sin&soi4.If t%e ti3e/8ar:ing analog 4ri8e signal is s=t>, t%en t%e

o&tp&t optical po(er P=t> is

P=t> B Pt0 ms=t>

If CNRiis t%e CNR for an it%noise so&rce,

t%e total CNR is


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-ig. /F1)aser analog 3o4&lation


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Here Pt is optical power level at the bias current point,

Modulation index m is given by 3B =Ppea7;Pt>

Typically, m for analog applications range from 0.25 to 0.50.

For a sinusoidal received signal, the carrier power at the

output of receiver is

2)(2

1PMmC =


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PHTDETECTR AMP)I-IER NI+E

P%oto4io4e noise is

B B FMF-=M>2e

CNR for t%e p%oto4etector onl: is

CNR4etB C;

Prea3plifier noise is

B B

CNR for t%e prea3plifier onl: is

CNRprea3pB C;


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RE)ATIVE INTEN+IT NI+E / RINIn an analog s:ste3 t%e 3ain noise so&rces are

/ T%er3al noise,

/ +%ot noise in t%e p%oto4etector,/ Relati8e intensit: noise =RIN> fro3 t%e laser.

RIN arises fro3 ran4o3 intensit: fl&ct&ations (it%in a

se3icon4&ctor laser, (%ic% pro4&ce optical intensit:noise.

T%ese fl&ct&ations co&l4 arise fro3 te3perat&re

8ariations or fro3 spontaneo&s e3ission containe4 in t%elaser o&tp&t.

RIN is 3eas&re4 in 4eci6els per %ert? (it% t:pical 8al&es

ranging fro3 0@! to 0!" 42;H?.


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Mean sF2e

RIN is 3eas&re4 6: 3ean s

RIN is / 3eas&re4 in 42;H?/ 4efine4 as Noise to +ignal po(er ratio


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is a8erage laser o&tp&t intensit:

RIN 4ecreases as 6ias c&rrent le8el increases as

RIN 8al&e for a 0!!" n3 D-2 laser is aro&n4

/0!F to /0! 42.


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CNR for a single c%annel AM s:ste3 is

2ac7 reflections can increase RIN 6: 0"/F" 42

teeqBeDpeN

s

FBRTkBMFMIIqBPRIN

PMm

i

i

N

C

)/4()()(2()(

)(2/1

22

2

2

2

+++

==


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-ig. /@1 RIN effects

-or in5ection c&rrent a6o8e

T%res%ol4=J0.F>, RIN for

in4e9 g&i4e4 lasers lie in

Range

/0$" to /0!" 42;H?.

at 0"" MH?.


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ptical recei8er CNR

Prea3plifier circ&it noise 4o3inates recei8er noise

-or (ell 4esigne4 p%oto4io4es, 6&l7 an4 s&rface

4ar7 c&rrents are s3aller t%an t%e s%ot noise

If laser %as large RIN t%en reflection noise 4o3inates

teeqB FBRTk

PMm

N

C

)/4(

)(2/1 2

=

eshot BMqF

Pm

N

C

)(2

2

1 2

=

( )

erefl BRIN

mM

N

C

.

2

1 2

=


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-ig. /#1 CNR 8ers&s optical po(er le8el

Effects of4ifferent

Noises on

CNR

at Hig% recei8e4 Po(er le8els, +o&rce noise

4o3inates to gi8e constant CNR


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MU)TI CHANNE) AM

-irst analog optical lin7 CATV 4istri6&tion CATV net(or7 4eli8er " AM V+2 8i4eo c%annels Eac% CH %as $ MH? noise 6an4(i4t% in a

# MH? CH 6an4(i4t% (it% an +NR of $K 42.

-ig./K s%o(s N CH -DM analog optical lin7


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Infor3ation signal on c%annel i a3plit&4e

Mo4&lates a carrier of fre


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N CH total 3o4&lation in4e9 3 is relate4 to t%e

per CH 3o4&lation in4e9 3i6:

W%en N signals are fre


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INTER MDU)ATIN PRDUCT+

W%en 3&ltiple carriers pass t%ro&g% a non linear4e8ice li7e a laser 4io4e, so3e &n4esira6le signal

-re


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E91/ !" CH CATV net(or7 of !!.F! to @K!.F! MH?

/ @ secon4 or4er IM tones at !$ MH?

/ K# t%ir4 or4er IM tones at FF.! MH?/ triple 6eat pro4&cts are @ 42 %ig%er t%an

F tone @r4or4er IM pro4&cts

No. of triple 6eat ter3s B N=N/0>=N/F>

No. of F tone @r4or4er ter3s B N=N/0>


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2EAT +TAC*ING1

If signal pass6an4 %as large no. of erO LLLLL Ffi/f5ter3s

No. of triple 6eat IM pro4&cts falling on rt%carrier is

D0,0B r;F=N/r0>0;$=N/@>F/!/0;F0/=/0>N=/0>NrO

LLL fif5/f7 ter3s


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F tone @r4or4er ter3s / e8enl: sprea4 in pass 6an4

Triple 6eat ter3s concentrate in pass6an4 3i44le

2eat stac7ing res&lts in

/ co3posite secon4 or4er =C+>/ co3posite triple 6eat =CT2>


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-ig. /1 Pre4icte4 C+ for #" CATV c%annels

Effect of C+ is 3ost significant at t%e e4ges of

pass6an4


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-ig. /1 Pre4icte4 CT2 for #" CATV c%annels

Effect of CT2 is 3ost significant at t%e center of

pass6an4


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MU)TI CHANNE) -M

M&ltic%annel AM nee4s 3in. of $" 42 CNR

for eac% CH, 6&t nee4s onl: $ MH? 6an4(i4t%

M&ltic%annel -M nee4s 3ore 6an4(i4t%=@" MH?>,

6&t :iel4s +NR i3pro8e3ent o8er t%e CNR.

+NRo&tof -M 4etector JJ inp&t CNR of -M 4etector

+NR i3pro8e3ent is

Total +NR i3pro8e3ent is in range of @#/$$ 42


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-ig. /0"1 RIN 8ers&s optical 3o4&lation in4e9

-or ! in4e9, AM s:ste3 (it% RIN of /0$" 42;H?can 6arel: 3eet CATV reception.

-M laser s:ste3 (it% RIN of /0F" 42;H? can easil:

Meet CATV reception


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-ig. /001 Po(er 6&4get 8s optical 3o4&lation in4e9

-or a ! in4e9, po(er 3argin for

AM s:ste3 //// 0" 42

-M s:ste3 //// F" 42


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+U2 CARIER MU)TIP)EQING

Capa6ilit: of 3&ltiple9ing 6ot% 3&ltic%annel analog

+ignals an4 t%e 4igital signals (it%in sa3e s:ste3


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+&6 Carrier M&ltiple9ing

Eac% 3o4&lating R- carrier (ill loo7 li7e a s&6/

carrier Un3o4&late4 optical signal is t%e 3ain carrier

-re 3&ltic%annel s:ste3s also calle4 as +CM

Fre!uency

Un3o4&late4 =3ain> carrier

"ub#carriers

f1

f2

f1

f2

f0


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+&6 Carrier M&ltiple9ing

A6ilit: to 6ot% analog an4 4igitall:

3o4&late4 s&6/carriers

Eac% R- carrier 3a: carr: 8oice, 4ata, HD

8i4eo or 4igital a&4io T%e: 3a: 6e 3o4&late4 on R- carriers

&sing 4ifferent tec%ni


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CATV Distri6&tion

!"/ MH? an4 0F"/!!" MH? spectr&3 isallocate4 for CATV

Eit%er AM or -M tec%ni


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+&6carrier M&ltiple9ing =+CM>

Ma5or 4isa48. of TDM is c%ro3atic 4ispersion

WDM re &n4ergoes f&rt%er

3&ltiple9ing in R- 4o3ain prior to 6eing

trans3itte4 o8er a single (a8elengt%

A48. is t%e a8aila6ilit: of 3icro(a8e

co3ponents

Application is analog&e ca6le TV =CATV>


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R- VER -I2ER


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R- VER -I2ER

R- signals range fro3 / UH- 6an4 =".@/@ GH?> / +H- 6an4 =@."/@" GH?>

/ EH- 6an4 =@"/@"" GH?>

T%e: &se Coa9 ca6le or (ireless ra4io lin7s totransport 3icro(a8e signals

Hig% spee4 optical fi6er lin7s %a8e 3an:

a48antages to transport 3icro(a8e signals in t%eirriginal analog for3

T%ese are calle4 R- o8er fi6er s:ste3s

E R 4i fi6 =R-> t i t t


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E91/ Ra4io o8er fi6er=R-> s:ste3s interconnect

antenna 6ase stations (it% t%e central

controller office

2asic ele3ents of a generic R- 8er -i6er lin7


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@ 3a5or 3o4&les of R-- lin71

0. ptical to R- Con8erter =RQ>/ con8erts optical signal into R- signal

F. R- to ptical Con8erter =TQ>

/ con8erts R- signal into optical lig%t signal

@. ptical -i6er 5ois t%e t(o con8erter 3o4&les

Perfor3ance para3eters1

/ gain, noise fig&re, sp&r free 4:na3ic range

)i 7 G i


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)in7 Gain, g1

ratio of R- po(er o&t Po&tgenerate4 in p%oto4etector

)oa4 resistror to t%e R- po(er inp&t Pinto laser TQ.

-or 4irect 3o4&late4 lin7

Gain 8al&es gS 0 represent a lin7 loss

Ma5or contri6&tors to gain1

/ 3o4&lator slope efficienc: +M/ p%oto4etector responsi8it:

R

RTS

M

load

FDFLFMin

P

Pg out ==

22222

NI+E -IGURE


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NI+E -IGUREA 3eas&re of +NR 4egra4ation 6et(een inp&t an4

&tp&t of t%e lin7.

is total o&tp&t noise po(er in 6an4(i4t% 2

No&tis noise po(er per &nit 6an4(i4t%

At t%e lin7 o&tp&t, noise po(ers are1

No&t,RINB IPF=RIN>

No&t,s%otB F


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+PUR -REE D2AMIC RANGE =+-DR>

D:na3ic range of analog lin71- A3plit&4e relate4 to t%e f&n4a3ental an4

%ar3onic an4 IM 4istortion co3ponents

Consi4er F e


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+-DR specifies t%e relations%ip 6et(een t%e a3plit&4e of

t%e f&n4a3ental fre f ll t f Ff


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@r4or4er IM pro4&ct =IMD@> falls at a fre


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+-DR is 4efine4 as ratio 6et(een t%e po(ers of

-&n4a3ental carrier an4 t%e @r4or4er IM =IMD@>,

at a po(er le8el (%ere IMD@BNoise floor

+-DR is t%e &sa6le 4:na3ic range 6efore t%e

sp&rio&s noise interferes (it% an4 4istorts t%e

f&n4a3ental signal

T%&s, +-DR JCNR3inP

Direct 3o4&late4 3icro(a8e lin7s %a8e t:pical

+-DR of 0F! 42.H?F;@at 0 GH?.

RADI VER -I2ER


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RADI VER -I2ERI3portant application of R- o8er fi6er tec%nolog: is

2roa46an4 Wireless Access Net(or7s=2WAN>

2WANs interconnect t%e 2ase +tations=2+> (it%

T%e central controlling office=+(itc%>

Integration of the optical fiber networks & wirelessnetworks are called as the radio-over-fiber (RoF)networks

In RoF networks, radiofrequencies (RFs) are carriedover optical fiber links to support various wirelessapplications


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Trans3ission range aro&n4 a 2+ is calle4 a

/ Microcell (it% 4ia3eter less t%an a0 *3.

/ Picocell;Hotspot (it% ra4ii fro3 ! to !" 3.

2ase stations are connecte4 t%e 3icrocell control

+tation =C+> in t%e central office &sing opticalWDM lin7s

Eac% 2+ 3a: &se a separate &ni


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-i6er/optic 3icrocell&lar ra4io

2esi4e increase4 capacit:, 3icrocells also re4&cepo(er cons&3ption si?e of %an4set 4e8ices

Distri6&te4 antenna s:ste3 connecte4 to 6ase station8ia optical fi6ers a8oi4s 6ase station antenna (it%%ig%/po(er ra4iation BJ fi6er optic 3icrocell&lar ra4ios:ste3

Ra4io signals in eac% 3icrocell are trans3itte4 recei8e4 to fro3 3o6ile &sers 6: &sing a separates3all canister attac%e4 to 6ase station 8ia opticalfi6er

Eac% canister is e


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Fiber-optic microcellular radio

Remote odulation


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Remote odulation

Ra4io/o8er/+M- net(or7s


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Ra4io/o8er/+M- net(or7s

Ro- net(or7s s&pport 8ario&s 4igital for3ats an4(ireless stan4ar4s in cost/effecti8e 3anner

E9peri3ental 4e3o of Ro- net(or7 (as a6le tosi3&ltaneo&sl: trans3it follo(ing fo&r (irelessstan4ar4s in 4o(nstrea3 4irection &sing a singleantenna

WCDMA IEEE "F.00 W)AN

PH+

G+M

Electroa6sorption 3o4&lator =EAM> 6ase4 3et%o4co36ines se8eral ra4io signals onto co33on single/3o4e fi6er =+M-> BJ Ra4io/o8er/+M- net(or7s

Radio-over-!F networks


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Radio over !F networks

Radio-over-F networks


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F w

an" buildings have multimode fiber (F) cablesrather than !F links #$ radio-over-F networks

%ost-effective F-based networks can be realiedb" deplo"ing low-cost vertical-cavit" surface-emitting lasers ('%!s) operating in *+-nmtransmission window

perimental demonstration of indoor radio-over-F networks using different kinds of F incon.unction with commercial off-the-shelf (%/0!)components for in-building coverage of following fourwireless standards

1! 20!

I *3455 678

69 RoF networks


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69 RoF networks

69 RoF networks not onl" increase capacit" but alsoincreases number of base stations serviced b" a single central

station

perimental demo of 69 RoF ring network

69 fiber loop connects multiple remote nodes with central

office ach remote node deplo"s arra" of tunable F;1s 7 remote node is able to locall" drop one or more wavelengths b"

tuning its F;1s accordingl" !everal so-called radio access units (R72s) are attached to each

remote node ach R72 ma" serve one or more mobile users R/79s used at remote nodes allow add-drop wavelengths to be

d"namicall" assigned to remote nodes & attached R72s inresponse to given traffic loads

RoF & F00< networks


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RoF & F00< networks Future multiservice access networks can be realied b"

integrating RoF s"stems with eisting optical access networks,(e4g4, F00< networks)

0o achieve this, both wireless RF & wired-line (F00


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Mvr - Analog Links