Plesiochronous Digital Hierarchy.ppt

7/23/2019 Plesiochronous Digital Hierarchy.ppt

http://slidepdf.com/reader/full/plesiochronous-digital-hierarchyppt 1/23

PlesiochronousPlesiochronousDigital HierarchyDigital Hierarchy



PDHPDH

MULTIPLEXINGMULTIPLEXING

PLESIOCHRONOUS HIGHERPLESIOCHRONOUS HIGHER

ORDER DIGITLORDER DIGITL

MULTIPLEXINGMULTIPLEXING



PDH MUX NORTH MERICPDH MUX NORTH MERIC

The !" channel PCM syste# is theThe !" channel PCM syste# is the

$ri#ary or%er o& Digital MUX'$ri#ary or%er o& Digital MUX'

I& it is necessary to trans#it #ore than !"I& it is necessary to trans#it #ore than !"channels( the syste# is )uil%*u$ as in thechannels( the syste# is )uil%*u$ as in the

+Plesiochronous Digital Hierarchy, as+Plesiochronous Digital Hierarchy, as

sho-n in the %iagra#sho-n in the %iagra#



DIGITAL TRANSMISSIONDIGITAL TRANSMISSION

HIERARCHY HIERARCHY

TI MUX

T2 MUX

T3 MUX

T4 MUX

64kb/s

1

24 1.544 Mb/s

Four

1.544Mbits/s

Inputs

1

46.312 Mbits/s

Seven 6.312

inputs

1

7

274.17

Mbits

Six 44.736 Mbits/s

inputs

1

6



DIGITAL MUX LEVELS IN North America, Europe, apa!DIGITAL MUX LEVELS IN North America, Europe, apa!

Digital MUXDigital MUXLe.elLe.el

No'o& /"0)1sNo'o& /"0)1sChannelsChannels

North #ericaNorth #erica

M)its1sM)its1s

Euro$eEuro$eM)its1sM)its1s

2a$an M)its1s2a$an M)its1s

33 44 3'3/"3'3/" 3'3/"3'3/" 3'3/"3'3/"

44 !"!" 4'5""4'5"" 4'5""4'5""

6363 !'3"7!'3"7

"7"7 6'45!6'45! 6'45!6'45!

!! 8/8/ /'64!/'64! /'64!/'64!

4!34!3 7'""77'""7

66 "73"73 6"'6/76"'6/7 6!'3/"6!'3/"

/9!/9! ""'69/""'69/

46""46"" 84'35684'356

4""34""3 89'9!789'9!7

"" 48!348!3 468'!/"468'!/"

"36!"36! !9"'49/!9"'49/

59/359/3 689'!33689'!33



PDH MUXPDH MUX

:our $ri#ary syste#s ;!"*channle each<:our $ri#ary syste#s ;!"*channle each<

are co#)ine%( #ulti$le=e%( to &or# anare co#)ine%( #ulti$le=e%( to &or# an

out$ut ha.ing 8/ channels' This is calle%out$ut ha.ing 8/ channels' This is calle%

the secon% or%er o& #ulti$le=ing' Se.enthe secon% or%er o& #ulti$le=ing' Se.en

8/ channel syste#s can )e #ulti$le=e% to8/ channel syste#s can )e #ulti$le=e% to

gi.e an out$ut o& /9!* channels ;Thir%gi.e an out$ut o& /9!* channels ;Thir%

or%er o& Multi$le=ing<' Si= /9! > channelsor%er o& Multi$le=ing<' Si= /9! > channelssyste#s are #ulti$le=e% to gi.e an out$utsyste#s are #ulti$le=e% to gi.e an out$ut

o& "36! channels ;&ourth or%er<o& "36! channels ;&ourth or%er<



Secon% Or%er ;DS!<PDHSecon% Or%er ;DS!<PDH

MUX;4'5"" to /'64! M)1s<MUX;4'5"" to /'64! M)1s< The /'64!*M)1s out$ut o& a secon% or%er ;The /'64!*M)1s out$ut o& a secon% or%er ;DS2DS2<<

Multi$le=er is create% )y #ulti$le=ing &our &irstMulti$le=er is create% )y #ulti$le=ing &our &irst

or%er ;or%er ;DS1DS1< #ulti$le=ing out$uts' This is %one )y< #ulti$le=ing out$uts' This is %one )y

interlea.ing the )it strea# o& the &our $ri#aryinterlea.ing the )it strea# o& the &our $ri#arysyste#s'syste#s'

Each in%i.i%ual )it strea# is calle% theEach in%i.i%ual )it strea# is calle% the

++tributary”tributary”''

The #ain $ro)le# to o.erco#e in this $rocess isThe #ain $ro)le# to o.erco#e in this $rocess is

the organi?ation o& the &our inco#ing tri)utaries'the organi?ation o& the &our inco#ing tri)utaries'



Cont***Cont***

Synchronous Digital ha.e tri)utaries -ith the sa#eSynchronous Digital ha.e tri)utaries -ith the sa#ecloc@ &reAuency( an% they are all synchroni?e% to acloc@ &reAuency( an% they are all synchroni?e% to a

#aster cloc@'#aster cloc@'

Plesiochronous Digital Muti$le=ers are ha.e tri)utariesPlesiochronous Digital Muti$le=ers are ha.e tri)utaries

that ha.e the sa#e no#inal &reAuency ;that #eansthat ha.e the sa#e no#inal &reAuency ;that #eans

there can )e s#all %i&&erence &ro# one to another<( )utthere can )e s#all %i&&erence &ro# one to another<( )ut

they are not synchnroni?e% to each other'they are not synchnroni?e% to each other'

:or synchronous case( the $ulses in each tri)utary all:or synchronous case( the $ulses in each tri)utary allrise an% &all %uring the sa#e ti#e inter.al'rise an% &all %uring the sa#e ti#e inter.al'

:or the PDH( the rise an% &all ti#e o& the $ulses in:or the PDH( the rise an% &all ti#e o& the $ulses in

each tri)utaries %o not coinci%e -ith each other'each tri)utaries %o not coinci%e -ith each other'



PDH Euro$ePDH Euro$e

63 ch

!'3"7 M)1s

4!3 ch

7'""M)1s

"73 ch6"'6/7

M)1s

48!3 ch

468'!/"M)1s

9/73 ch

5/"'88!

M)it1s

/"

@)its1s

=63=

"

="="

="

Euro$e



Interlea.ingInterlea.ing

The #ulti$le=ing o& se.eral tri)utaries canThe #ulti$le=ing o& se.eral tri)utaries can

)e achie.e% )y either )e achie.e% )y either

Bit )y )it #ulti$le=ing ;)it interlea.ing<Bit )y )it #ulti$le=ing ;)it interlea.ing<

or% )y -or% #ulti$le=ing ;)yteor% )y -or% #ulti$le=ing ;)yte

interlea.ing<interlea.ing<



BIT INTERLEINGBIT INTERLEING

There are &our )it strea#s to )eThere are &our )it strea#s to )e

#ulti$le=e%' One )it is seAuentially ta@en#ulti$le=e%' One )it is seAuentially ta@en

&ro# each tri)utary so that the resulting&ro# each tri)utary so that the resulting

#ulti$le=e% )it strea# has e.ery &i&th )it#ulti$le=e% )it strea# has e.ery &i&th )it

co#ing &ro# the sa#e tri)utary' s$eci&icco#ing &ro# the sa#e tri)utary' s$eci&ic

no' o& )its ;usually 7<( &or#ing a -or%( areno' o& )its ;usually 7<( &or#ing a -or%( are

ta@en &ro# each tri)utary in turn'ta@en &ro# each tri)utary in turn'



Byte Interlea.ingByte Interlea.ing

Byte interlea.ing sets so#e restraints onByte interlea.ing sets so#e restraints on

the &ra#e structure o& the tri)utaries an%the &ra#e structure o& the tri)utaries an%

reAuire great a#ount o& #e#ory ca$acity'reAuire great a#ount o& #e#ory ca$acity'

Bit interlea.ing is #uch si#$ler )ecause itBit interlea.ing is #uch si#$ler )ecause it

is in%e$en%ent o& &ra#e structure an% alsois in%e$en%ent o& &ra#e structure an% also

reAuires less #e#ory ca$acity'reAuires less #e#ory ca$acity'



PDH &eaturesPDH &eatures

Bit interlea.ing is use% &or North #ericanBit interlea.ing is use% &or North #erican

an% Euro$ean PDH syste#' ty$ical /'64!an% Euro$ean PDH syste#' ty$ical /'64!

M)1s $lesichronous #ulti$le=er has &ourM)1s $lesichronous #ulti$le=er has &our

$ri#ary ;DS4< MUX( each ha.ing an out $ut$ri#ary ;DS4< MUX( each ha.ing an out $ut

o& 4'5"" M)1s( )it interlea.e% to &or# theo& 4'5"" M)1s( )it interlea.e% to &or# the

ne=t le.el in hierarchy'ne=t le.el in hierarchy'

Note that this out$ut rate o& /'64! M)1s is notNote that this out$ut rate o& /'64! M)1s is note=actly &our ti#es the tri)utary )it rate o&e=actly &our ti#es the tri)utary )it rate o&

4'5"" M)1s' This is a result o& the non*4'5"" M)1s' This is a result o& the non*

sychronous nature o& the syste#'sychronous nature o& the syste#'



PDH :eaturesPDH :eatures

E.ery tri)utary has its o-n cloc@' E.ery tri)utaryE.ery tri)utary has its o-n cloc@' E.ery tri)utaryis ti#e% -ith $lesiochronous &reAuency( that is ais ti#e% -ith $lesiochronous &reAuency( that is ano#inal &reAuency a)out -hich the shi&ts aroun%no#inal &reAuency a)out -hich the shi&ts aroun%

it -ithin $re&i=e% li#its' :or e=a#$le( the $ri#aryit -ithin $re&i=e% li#its' :or e=a#$le( the $ri#ary#ulti$le=er out$ut is 4'5"" M)1s * 53$$#'#ulti$le=er out$ut is 4'5"" M)1s * 53$$#'

To account &or the s#all .ariations o& theTo account &or the s#all .ariations o& thetri)utaries &reAuencies a)out the no#inal .aluetri)utaries &reAuencies a)out the no#inal .alue

-hen #ulti$le=ing &our tri)utaries to the ne=t-hen #ulti$le=ing &our tri)utaries to the ne=thierarchy le.el( a $rocess @no-n as $ositi.ehierarchy le.el( a $rocess @no-n as $ositi.estu&&ing ;also @no-n as $ositi.e Fusti&ication< isstu&&ing ;also @no-n as $ositi.e Fusti&ication< isuse%'use%'



Positi.e Pulse stu&&ing orPositi.e Pulse stu&&ing or

Fusti&ication Fusti&ication

Pulse stu&&ing in.ol.es intentionally #a@ing thePulse stu&&ing in.ol.es intentionally #a@ing theout$ut )it rate o& a channel higher than theout$ut )it rate o& a channel higher than thein$ut rate' The out$ut channel there&orein$ut rate' The out$ut channel there&orecontains all the in$ut %ata $lus a .aria)lecontains all the in$ut %ata $lus a .aria)le

nu#)er o& +stu&&e% )its that are not $art o& thenu#)er o& +stu&&e% )its that are not $art o& theinco#ing su)scri)er in&or#ation'inco#ing su)scri)er in&or#ation'

The stu&&e% )its are inserte% at the s$eci&icThe stu&&e% )its are inserte% at the s$eci&ic

locations( to $a% the in$ut )it strea# to thelocations( to $a% the in$ut )it strea# to thehigher out$ut )it rate' This stu&&e% )its #ust )ehigher out$ut )it rate' This stu&&e% )its #ust )ei%enti&ie% at the recei.ing en% so that +%e*i%enti&ie% at the recei.ing en% so that +%e*stu&&ing, can )e %one to reco.er the original )itstu&&ing, can )e %one to reco.er the original )it

strea#'strea#'



Cont***Cont***

Pulse stu&&ing is use% &or higher or%erPulse stu&&ing is use% &or higher or%er

#ulti$le=ing -hen each o& the inco#ing#ulti$le=ing -hen each o& the inco#ing

lo-er or%er tri)utary signal islo-er or%er tri)utary signal is

unsynchroni?e%( an% there&ore )ears nounsynchroni?e%( an% there&ore )ears no

$re&i= $hase relationshi$ to any o& the$re&i= $hase relationshi$ to any o& the

other'other'

The situation is .i.i%ly %e$icte% in &ig'The situation is .i.i%ly %e$icte% in &ig'






BTE INTERLEINGBTE INTERLEING

Word by Word MULTIPLEXING




SIMPLI:IED SDH MULTIPLEXINGSIMPLI:IED SDH MULTIPLEXING

SNCHRONOUS BE INTERLEINGSNCHRONOUS BE INTERLEING

;No Stu&&ing nee%e%<;No Stu&&ing nee%e%<

HIGR ORDER

MULTIPLEXER



Si#$li&ie% PDH )it interlea.ingSi#$li&ie% PDH )it interlea.ing

;Stu&&ing Nee%e%<;Stu&&ing Nee%e%<

** **Higher

Or%er

Multi$le=er

44

:ra#e no'4 :ra#e no !

Lo-er Bit Rate

Higher Bit Rate

Stu&&ing

Control )it Stu&&ing

)it is a%ata )it

Stu&&ing )it

is a stu&& )it



De*stu&&ing at Recei.e si%eDe*stu&&ing at Recei.e si%e t the recei.ing en% the -riting cloc@ has the sa#e t the recei.ing en% the -riting cloc@ has the sa#e

characteristics as those o& the trans#it rea%ing cloc@'characteristics as those o& the trans#it rea%ing cloc@'That is( it has a &reAuency that is on a.erage the sa#eThat is( it has a &reAuency that is on a.erage the sa#e

as that o& the tri)utary( )ut it $resents $erio%ic s$acesas that o& the tri)utary( )ut it $resents $erio%ic s$aces

&or the &ra#e structure an% ran%o# s$aces &or the&or the &ra#e structure an% ran%o# s$aces &or the

stu&&ing $rocess' $hase loc@ loo$ ;PLL< circuit isstu&&ing $rocess' $hase loc@ loo$ ;PLL< circuit isuse% to re%uce(use% to re%uce(

2itter cause% )y the &ra#e structure2itter cause% )y the &ra#e structure

Higher &reAuency Fitter co#$onents ;-aiting ti#e<Higher &reAuency Fitter co#$onents ;-aiting ti#e<cause% )y stu&&ingcause% )y stu&&ing

Tri)utary signal Fitter Tri)utary signal Fitter

2itter intro%uce% )y the /'64! M)1s lin@'2itter intro%uce% )y the /'64! M)1s lin@'



PDH MUX Euro$ePDH MUX Euro$e

In su##ary( the $ositi.e stu&&ing #etho% in.ol.esIn su##ary( the $ositi.e stu&&ing #etho% in.ol.esthe canceling o& a cloc@ $ulse assigne% to athe canceling o& a cloc@ $ulse assigne% to a$articular tri)utary in so#e o& the &ra#es in or%er to$articular tri)utary in so#e o& the &ra#es in or%er tocoor%inate the ti#ing o& the $lesiochronouscoor%inate the ti#ing o& the $lesiochronoustri)utaries into a #ulti$le=e% out$ut' Ran%o#tri)utaries into a #ulti$le=e% out$ut' Ran%o#s$aces are there&ore create% in the &ra#e( as -ells$aces are there&ore create% in the &ra#e( as -ellas $erio%ic s$aces' In the $erio%ic s$aces &ra#eas $erio%ic s$aces' In the $erio%ic s$aces &ra#ealign#ent -or% )its ser.ice )its( an% stu&&ing controlalign#ent -or% )its ser.ice )its( an% stu&&ing control)its are inserte%' The tri)utary in&or#ation )its are)its are inserte%' The tri)utary in&or#ation )its areinserte% in the ran%o# s$aces in the a)sence o&inserte% in the ran%o# s$aces in the a)sence o&stu&&ing( or logic 4 is use% -hen stu&&ing ta@enstu&&ing( or logic 4 is use% -hen stu&&ing ta@en$lace' Re#e#)er( the stu&&ing $luses carry no$lace' Re#e#)er( the stu&&ing $luses carry no

su)scri)er in&or#ation'su)scri)er in&or#ation'



PDH ENDPDH END

THANKSTHANKS

Documents

Plesiochronous Digital Hierarchy.ppt