01-2 intro to transmission systems 2010-08-10-r1a

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11 Rev 2010-08-10

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Introduction to Transmission Systems

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201-2 Intro to Transmission Systems

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PDH (Plesiochronous Digital Hierarchy)

PDH is a technology used in telecommunications networks to transport large quantities of data over

digital transport equipment.

The term plesio-chronous refers to the fact that PDH networks run in a state where different parts of the

network are nearly, but not quite perfectly, synchronized.

Difference in clock between PDH elements is compensated by signalling between the Tx and Rx to

indicate missing bits.

The transmitting multiplexer adds additional bits to allow the far end receiving multiplexer to decode

which bits belong to which 2-Meg data stream. These additional bits are called "justification" or "stuffing"

bits.

The basic unit in PDH is called the E0 and has a rate of 64Kbps.

There are two different PDH systems, European and American systems.

139264 KbpsE4

34368 KbpsE3

8448 KbpsE2

2048 KbpsE1

64 KbpsE0

Data RateNotation

139264 KbpsT4/DS4

44736 KbpsT3/DS3

6312 KbpsT2/DS2

1544 KbpsT1/DS1

64 KbpsT0/DS0

Data RateNotation

European Standard

(30 E0 + 2 E0 for signalling)

American Standard

(24 E0 + framing bits)

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PDH Limitations

No world standard on digital format. Making equipment to convertdifferent standards is costly.

No world standard for optical interfaces. Networking is impossible at the optical level.

Rigid asynchronous multiplexing structure. No direct multiplexing.

Limited management capability.

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SDH (Synchronous Digital Hierarchy)

International Telecommunication Union ITU standard

First set of SDH recommendations released in 1988

A flexible and efficient method to convey digital information from one designated location to another

An international standard for high-speed optical and electrical telecommunications networks

Solution for data-transmission in broadband telecommunications network

SDH

Transport

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Advantages of SDH

Direct mapping (transport) of PDH (TDM), ATM and IP signals

Effective and powerful multiplexing, de-multiplexing and cross connecting

Standardised NNI for both optical and electrical interfaces

Dynamic network protection in ring topology (self healing)

In service supervision and management for all Network Elements (NE)

Centralised network control and timing recourses

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Components and topology

Network elements

DXC - Digital Cross ConnectADM - Add/Drop Multiplexer

TM - Terminal MultiplexerRT - Radio Terminal

RR - Radio RepeaterOR - Optical Repeater

Typical Capacity

Access network: PDH, STM-0, STM-1Regional network: STM-1, STM-4, STM-16

National network: STM-16, STM-64

ADM

ADMADM

Regionalnetwork(Ring)

Access network(Chain)

RT RTRR

RTRT

National network(Mesh)

DXC

DXCRTDXC OR RT

ORDXC OR

TM

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The SDH frame

Frame header + Payload = Synchronous Transport Module (STM)

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MSOH

AU - pointers

STM STM --1 payload1 payload

RSOH

261 bytes

270 bytes

9 bytes

3 rows

5 rows

1 row

STM - 1 bit rate:

8000 frames/sec x 9 rows/frame x 270 bytes/row x 8 bits/byte = 155.520 Mb/s

STM-1 Frame Structure

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MSOH

AU - pointers

STM STM --n payloadn payload

RSOH

nx261 bytes

nx270 bytes

nx9 bytes

3 rows

5 rows

1 row

STM - n bit rate:

nx8000 frames/sec x 9 rows/frame x 270 bytes/row x 8 bits/byte = nx155.520 Mb/s

STM-n Frame Structure

40 Gbps39813.12 MbpsSTM-256

10 Gbps9953.280 MbpsSTM-64

2.4 Gbps2488.320 MbpsSTM-16

622 Mbps622.080 MbpsSTM- 4

155 Mbps155.52 MbpsSTM-1

51 Mbps51.84 MbpsSTM-0

AKABit RateSignal name

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Section Layers

MST - Multiplexer Section Termination (DXC, ADM, TM)

RST - Regenerator Section Termination (RT, RR, OR)MS - Multiplexer Section

RS - Regenerator Section

RSTMSTMSTMST

RST RST RSTRST

RS RSRS RS

MS

RSRSRS

MS

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RSTMSTMSTMST

RST RST RSTRST

RS RSRS RS

MS

RSRSRS

MS

Path layer

Higher order pathVC-3 (34 Mb/s)

VC-4 (140 Mb/s)

Mapped ATM / IP

Path Layers

Lower order path VC-12 (2Mb/s)

Mapped ATM / IP

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SDH Multiplexing Structure

Pointer

Processing

Multiplexing

Mapping

C-nx : Container

VC.nx : Virtual Container

TU-nx :Tributary UnitAU-n : Administrative Unit

TUG-n : Tributary Unit Group

STM-N : Synchronous Transport Module

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VC-12 Mapping Structure

C-12Container for 2.048 Mb/s C - 12

C-12VC - 12 POH VC - 12

POH C-12TU - pointer TU - 12

TU - 12TU - 12TU - 12Byte interleave 3 x TU - 12 TUG - 2

Byte interleave 7 x TUG - 2

TUG - 3

Byte interleave 3 x TUG - 3

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

C-4

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VC - 4 POH VC - 4

RSOH

STM - 1

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

PO

H

AU - PointerAU - 4

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12

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TU - 12

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

PO

HAU-Pointer

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12

TU - 12TU - 12TU - 12

TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12

TU - 12TU - 12TU - 12

TU - 12

J0A 2AAA 1A 1A 1 A2 A2 A

B 1 E 1 F1 N N

D1 D 2 D3

H 2 H2 H 2 H3 H3 H3H1

B 2 B 2 B 2 K 1 K2

D4 D 5 D6

D7

D10

S1 Z 1 Z1 Z 2 Z2 M1 E2 N

D9

D1 2

D 8

D 11

N

H1

A 1A 1

H1

A 1

MS 2

SI

#1 #2 #3

N

MS 3

MS 1

NV

C-4

PO

H

MSOH

VC-12 Mapping Structure

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VC-4 structure: Can be used to map 150Mb/s

Ethernet traffic.

Mixed TU-12/TU-3 structure: Each TU-12 can be

used to map approx. 2Mb/s Ethernet traffic or E1

traffic. Each TU-3 can be used to map approx.

50Mb/s Ethernet traffic or E3/DS3 traffic.

TU-3 structure: Each TU-3 can be used to map

approx. 50Mb/s Ethernet traffic or E3/DS3 traffic.

TU-12 structure: Each TU-12 can be used to map

approx. 2Mb/s Ethernet traffic or E1 traffic.

STM-1 Structure Examples

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J0A2AAA1A1A1 A2 A2 A

B1 E1 F1 N N

D1 D2 D3

H2 H2 H2 H3 H3 H3H1

B2 B2 B2 K1 K2

D4 D5 D6

D7

D10

S1 Z1 Z1 Z2 Z2 M1 E2 N

D9

D12

D8

D11

N

STM-1RSOH

POINTER

STM-1MSOH

H1

A1A1

H1

A1MS

2Mb/s

Media Specificbytes

2 Mb/s asynchronous

.

MS 2

SI

#1 #2 #3

N

MS 3

MS 1

SI : Stuffing for 2Mb/s Wayside

MS 1&2 : Radio Protection Switching control

MS 3 : RF-IdRemote reset

ATPCE/M for bytes; E1, F1, E2

N

SOH - Section Overhead

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A1/A2 - STM -1 frameword. (A1: 11110110, A2: 00101000)

J0 - Regenerator section trace

B1 - Regenerator section error calculation (BIP-8)

E1 - Regenerator Orderwire

F1 - Regenerator User channel

D1/D2/D3 - Data Communication Regenerators (192Kb/s)

NU - National Use

MS - Media Specific bytes

UN - UNallocated bytes

A1 A1 A1 A2 A2 A2 J0 NU NU

B1 MS MS E1 UN UN F1 NU NU

D1 MS UN D2 UN UN D3 UN UN

RSOH - Byte Description

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B2 - Multiplexer section error calculation (BIP-24)

K1/K2 - Multiplexer protection switching

D4-D12 - Data Communication Channel multiplexer (576Kb/s)

Z1/Z2 - Reserved for future use

E2 - Multiplexer Orderwire

S1 - Syncronization status

M1 - Multiplex Section - Remote Error Identifier (MS-REI)

NU - National Use

UN - UNallocated bytes

B2 B2 B2 K1 UN UN K2 UN UN

D4 UN UN D5 UN UN D6 UN UN



S1 Z1 Z1 Z2 Z2 M1 E2 NU NU

MSOH - Byte Description

01-2 intro to transmission systems 2010-08-10-r1a

Documents

transmission systems2201

pdh networks

pdh elements

digital transport equipment

regional network

different pdh systems

international standard

digital information