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Digital Carrier Systems. Digital carrier standard. T-carrier North America, Japan E-carrier Europe, Mexico, South America. T1 carrier system. PCM. PCM. PCM. MUX. DS-1 frame. DEMUX. PCM. PCM. PCM. DS-1 frame. each channel also refers as DS0. 125 m s. frame bit. channel #1.

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digital carrier standard
Digital carrier standard
  • T-carrier
    • North America, Japan
  • E-carrier
    • Europe, Mexico, South America
t1 carrier system
T1 carrier system

PCM

PCM

PCM

MUX

DS-1 frame

DEMUX

PCM

PCM

PCM

ds 1 frame
DS-1 frame
  • each channel also refers as DS0

125 ms

frame

bit

channel

#1

channel

#2

. . . . . . .

channel

#24

8 bit

193 bits

data rate = (24x8 +1 bit)/125 ms = 1.544 Mbps

t carrier
T - carrier

Two 1.544 Mbps DS1 channels are multiplexed into a single 3.152 Mbps DS1C channel

DSI

DSI

Two DS1C channels are multiplexed into a single 6.312 Mbps DS2 channel

DSIC

DSIC

Seven DS2 channels are multiplexed into a single 44.736 Mbps DS3 channel

DS2

DS2

DS2

DS2

DS2

DS2

DS2

DS3

DS3

DS3

DS3

DS3

DS3

Six DS3 channels are multiplexed into a single 274.176 Mbps DS4 channel

DS4

e1 frame

0

1

2

16

31

E1-frame

125 ms = 32 time slots = 2.048 Mbps

signaling channel

frame synchronization

30 voice channel+2 control channel

e carrier
E - carrier

Thirty 64 kbps channels are multiplexed to create one 2.048 Mbps E1 channel

E1

E1

E1

E1

Four E1 channels are multiplexed into a single 8.448 Mbps E2 channel

E2

E2

E2

E2

Four E2 channels are multiplexed into a single 34.368 Mbps E3 channel

E3

E3

E3

E3

Four E3 channels are multiplexed into a single 139.264 Mbps E4 channel

E4

E4

E4

E4

Four E4 channels are multiplexed into a single 565.148 Mbps E5 channel

E5

digital carrier comparison
Digital carrier comparison

Europe

E1

E2

E3

E4

E5

x31

x 4

x 4

x 4

x 4

2.048

8.448

34.368

139.264

564.992

T1

T2

T3

T4

x24

x 4

x 7

x 6

USA

64

1.544

6.312

44.736

274.176

J1

J2

J3

J4

J5

x24

x 4

x 5

x 3

x 4

1.544

6.312

32.064

97.728

397.200

Japan

slide9
PDH
  • Digital tramsmission systems (T-carrier, E carrier) combine lower order multiplex stream to get higher bit rate
  • Different streams have small differences in clock signals.
  • Solve by adding justification bit
  • PDH = Plesiochronous Digital Hierachy

almost synchronous

pdh deficiencies i
PDH deficiencies (I)
  • Lack of flexibility
    • impossible to identify a lower bit rate channel from the higher-order bit stream.

Extraction of 2 Mbps channel from 140 Mbps channel

34 Mbps

140 M

LTE

140 M

LTE

140

140

34

34

8 Mbps

34

34

8

8

2 Mbps

demux the high bit

rate down to the lower level

remux back into higher

level for onward transmission

8

8

2

2

Customer site

pdh deficiencies ii
PDH deficiencies (II)
  • Lack of performance
    • No standard for monitoring the performance of traffic channel
    • No management channel
pdh deficiencies iii
PDH deficiencies (III)
  • Lack of 慚id-Fibre meet
    • undefined interface specification on the line side of a line transmission

PDH

SDH

LTE

standard Network

Node Interface (NNI)

non standard

line code and

optical levels

G.703

interface

functional integration

of MUX and LTE

sdh sonet
SDH & SONET
  • What is SDH/SONET ?
    • Standard interface developed for using in the public network
    • multiplexing standard for optical fiber transmission
  • SONET = Synchronous Optical Network
    • refers to the system used within the U.S. and Canada
  • SDH = Synchronous Digital Hierarchy
    • international community term (ITU-T recommendtions)
sdh goals
SDH goals
  • Goals
    • make it possible for different carrier to interwork
    • unify the U.S., European and Japanese digital system
    • Provide a way to multiplex multiple digital signal togethers
    • provide support for operations, administration, and maintenace
  • Characteristics
    • use single master clock to synchronize
    • Bit stream can be a added or extracted directly
    • Basic transmission rate = 155.52 Mbps
signaling rates
Signaling rates

SONET

SDH

Bit rate (Mbps)

STS-1/OC-1

51.84

STS-3/OC-3

STM-1

155.52

STS-9/OC-9

STM-3

466.56

STS-12/OC-12

STM-4

622.08

STS-18/OC-18

STM-6

933.12

STS-24/OC-24

STM-8

1244.16

STS-36/OC-36

STM-12

1866.24

STS-48/OC-48

STM-16

2488.32

STS = Synchronous Transport Signal

OC = Optical Carrier

STM = Synchronous Transport Module

synchronous container
Synchronous Container

6 Mbps

2 Mbps

1.5 Mbps

PDH signal

2 Mbps

6 Mbps

1.5 Mbps

container

virtual

container

2 Mbps

6 Mbps

1.5 Mbps

Path overhead for

monitoring抯 purpose

Each PDH stream is carried

in an appropiate container

syncronization techniques
Syncronization抯 techniques

sample frame

  • phase offset in byte
  • directly access signal
  • signal using pointer
  • data begins anywhere
  • in frame

pointer

frame #1

data #1

data #1

POH #1

data #1

data #1

pointer

frame #2

data #2

POH #2

data #2

sonet system
SONET System
  • consists of switches, mux and repeaters

mux

repeaters

mux

repeaters

mux

section

section

section

section

line

line

path

sonet basic frame structure
SONET Basic Frame structure

1 frame = 810 bytes in 125ms

1 2 3 4 5 6 7 8 9

STS-1/OC1

row/column mapping

3 bytes

87 bytes

Overhead :

for system management

information

SOH = Section Overhead

LOH = Line Overhead

TOH = Transport Overhead

Payload : user data

SOH

3 bytes

Payload

9 bytes

LOH

6 bytes

TOH

sdh basic frame structure
SDH Basic Frame structure

1 frame = 2430 bytes in 125ms

1 2 3 4 5 6 7 8 9

STM-1

row/column mapping

9 bytes

261 bytes

Overhead :

for system management

information (OAM)

SOH = Section Overhead

LOH = Line Overhead

TOH = Transport Overhead

Payload : user data

SOH

3 bytes

Payload

9 bytes

LOH

6 bytes

TOH

stm 1 frame
STM-1 Frame

9 bytes

261 bytes

SOH

pointer

frame #1

Payload #1

Payload #1

POH #1

LOH

Payload #1

SOH

Payload #1

pointer

frame #2

Payload #2

POH #2

Payload #2

LOH

soh loh and poh
SOH, LOH and POH

transport

overhead

STS-1

information payload

A1 A2 C1 J1

B1 E1 F1 B3

D1 D2 D3 C2

H1 H2 H3 G1

B2 K1 K2 F2

D4 D5 D6 H4

D7 D8 D9 Z3

D10 D11 D12 Z4

Z1 Z2 E2 Z5

section

overhead

9 rows

line

overhead

87 columns

3 columns

path

overhead

sdh mux scheme
SDH mux scheme

PDH

Tributaries

STM-1

x1

AUG

AU-4

140 Mbps

VC-4

C-4

x3

TU-3

VC-3

TUG-3

x3

x7

45 Mbps

AU-3

C-3

VC-3

34 Mbps

x1

x7

6 Mbps

VC-2

TUG-2

C-2

TU-2

x3

SONET-specific

2 Mbps

C-12

TU-12

VC-12

Europe-specific

x4

Universal

VC-11

1.5 Mbps

TU-11

C-11

sdh elements
SDH Elements

Tributary Unit

Tributary Unit

Containers

path overhead

Tributary Unit Group

Tributary Unit Group

Virtual Containers

pointer

Administrative Unit

Administrative Unit

Tributary Unit

Administrative Unit Group

section overhead

STM-1

containers mapping
Containers mapping

sample C2 mapping

C-12

E1

fixed stuff

alignment

fixed stuff

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

17 18 19 20 21 22 23 24 25 26 27 28 29 30

signaling

containers #bytes capacity

C-11 25 1.600

C-12 34 2.176

C-2 106 6.784

C-3 672 48.384

C-4 2340 149.760

containers vc tu
Containers, VC & TU

C-2

C-11

C-12

9 bytes

4 bytes

3 bytes

12 bytes

VC-11

VC-12

VC-2

plus POH

TU-11

TU-12

TU-2

plus pointer

tu x format
TU-X format

3 columns

125 ms

1 2 3

27 bytes

1728 kbps

9 rows

TU-11

1 2 27

27

125 ms

4 columns

36 bytes

1 2 3 4

TU-12

9 rows

2304 kbps

1 2 36

36

12 columns

6912 kbps

125 ms

1 2 3

108 bytes

9 rows

TU-2

1 2 108

108

tug 2 to vc 3
TUG-2 to VC-3

3xTU-12

4xTU-11

1xTU-2

  • TUG-2 may be
    • 4xTU-11
    • 3xTU-12
    • 1xTU-2

9 bytes

12 bytes

12 bytes

12 bytes

12 bytes

TUG-2

9 bytes

7xTUG2

VC-3

9 bytes

1

84

total 85 columns

POH

au 3 to aug

J1

B3

C2

G1

F2

H4

Z3

Z4

Z5

J1

B3

C2

G1

F2

H4

Z3

Z4

Z5

J1

B3

C2

G1

F2

H4

Z3

Z4

Z5

J1

B3

C2

G1

F2

H4

Z3

Z4

Z5

J1

B3

C2

G1

F2

H4

Z3

Z4

Z5

J1

B3

C2

G1

F2

H4

Z3

Z4

Z5

H1 H2 H3

H1 H2 H3

H1 H2 H3

AU-3 to AUG

1 30 59 87

1 30 59 87

1 30 59 87

VC-3 plus

2 column

fixed stuff

1 30 59 87

1 30 59 87

1 30 59 87

AU-3

A

B

C

3xAU-3 to AUG

A B C A B C A B C

A B C

A B C A B C

tug 3 to vc 4
TUG-3 to VC-4

TUG-3

VC-3

TU-3

TU-3

PTR

C-3

9

85

justification

bytes

86

3xTUG-3

fixed stuff

VC-4

P

O

H

total 260 columns

high order mux
High order mux

STM-1 #1

stream

STM-1 #N

STM-1 #2

MUX

byte interleave

Nx9

Nx261

1xoc3 and 3xoc1
1xOC3 and 3xoC1
  • OC3 = 3xOC1
    • a 155.52 Mbps carriers consisting of 3 separated OC3 carriers
  • OC3c = 1X155.52Mbps carriers
    • a data stream from single source of 155.52 Mbps
  • Higher-order frames also exist (e.g. OC12c).
  • The amount of actual user data in an OC3c stream is slighly higher thanin an OC-3 stream!
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