02 Sn2cvxzv010eu13sn 0002 System Overview Ewsd

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System Overview EWSD Siemens

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Contents

1 EWSD in ISDN 3

1.1 Applications of EWSD in the ISDN 4

1.2 EWSD Feature Overview 6

2

EWSD Hardware Overview 9

2.1 Mechanical Design 10

2.2 Overview: System Architecture 12

3 Functional Structure of the Digital Line Unit (DLU) 19

3.1 Function Overview DLU B/D 20

3.2 Overview of DLU G Functions 32

3.3 xDSL Interfaces at EWSD DLU 44

4 Functional Structure of the Line Trunk Group (LTG) 47

4.1 External 2 Mbps Interfaces to LTG 48

4.2

Function Overview LTG 504.3 LTG Functional Types 52

4.4 Functional Units of the LTG 54

5 Functional Structure of the Remote Switching Unit RSU 57

5.1 Function Overview 58

5.2 RSU Functional Units 60

5.3 RSU Capacity Stage 62

5.4 RSU Emergency Operation 64

6 Functional Structure of the Switching Network (SN) 67

6.1

Internal EWSD Interfaces on the SN 68

6.2 Function Overview SN 70

System Overview EWSD


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6.3 SN B (EWSD-CLASSIC) 72

6.4 SN D (EWSD-POWERNODE) 76

7 Functional Structure of the Coordination Processor (CP) 81

7.1

Function Overview CP 82

7.2 System Features of the CP113 84

7.3 Functional Units of the CP 86

7.4 Input-Output Processors of the CP113 88

8 Functional Structure of the SS7 Network Control 91

8.1 Function Overview of the SS7 Network Control 92

8.2 Structure of the CCNC 96

8.3 Structure of the Signaling System Network Control SSNC 100

9 Application Program System (APS) 107

9.1

Components of the APS 108

9.2 APS Facts 110

10 Overview: EWSD Internal Call Setup 113

11 Exercise 119

12 Solution 123


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3

1 EWSD in ISDN


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1.1 Applications of EWSD in the ISDN

The fully digital switching system EWSD was released on the world market in 1981and has since then been constantly further developed.

In addition to the standard EWSD exchange which is offered in different hardwareconfigurations, the following special solutions are also available:

For lightly populated areas, it is however possible to use very small exchangesfrom the EWSCountry range (e.g. the Small Digital Exchange SDE for up to 3000subscribers).

If there is no infrastructure for telecommunications equipment, EWSD can then bedelivered in containers which in addition to the EWSD switching equipment, alsocontain the required equipment for power supply, air conditioning, transmission

technology and a main distributor.

Application options in ISDN/PSTN:

Local network node:

Up to 250,000 analog/digital subscribers (1 million in the EWSD powernode) canbe connected either directly or via V5 interfaces using access networks.With direct connection, the EWSD units for subscriber interfaces can be installedboth remotely and in exchange buildings. Remote installation (Remote DLU /Remote Switching Unit RSU) supports the direct connection of subscribers ofdifferent local networks to one EWSD.

It is also possible to offer with EWSD a so called high bit rate access to theInternet (i.e., the hardware required for xDSL solutions can be integrated intoEWSD).Furthermore EWSD can be equipped with an integrated Point of Presence PoP(Remote Access Server for 64kb/s Internet access of dial-in users).These two options enable internet traffic off loading in the local EWSD networknode.

Transit network nodes:

Up to 60,000 digital trunks (240,000 in the EWSD powernode) from/to other

exchanges can be connected to EWSD via 2Mbps PCM routes. The 2Mb/sinterfaces for the trunks can be installed both in the exchange building or remotely(Remote Switching Unit RSU solution).

Gateway network nodes:

EWSD offers networks of other operators/countries all gateway functions such asinternational signaling procedures, echo compensation for inter-continentalconnections or satellite routes and inter-administrative billing and statistics.


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Service Switching Point SSP of the IN:

EWSD can serve as SSP for IN connections. EWSD can also support the dialogbetween subscriber and Service Center Point SCP (User Interactive Dialog) using

voice recognition and individual announcement systems. It also provides access toexternal intelligent peripherals such as voice or faxmail systems.

All applications can be combined in an exchange.

direct connection of

subscribers via local

DLU or remote RDLU/RSU V5 interfaces to theaccess networks

Local Node

(optional with

internet trafficoff-loading)

Transit Node

EWSD

Gateway Node Service Switching Point SSP

EWSD in the ISDN/PSTN

S IE ME NS S IE ME NS SIEMENS

S IE ME NS S IE ME NS SIEMENS

SIEMENS SIEMENS S IE MENS SIEMENS SIEMENS SIEMENS

Local or remote (via RSU)connection of 2 Mb/s

systems (E1)

Fig. 1

TIP

It is also possible to configure EWSD in such a way that it can be used as a verypowerful stand alone Signaling Transfer Point STP (called hiS700).


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1.2 EWSD Feature Overview

EWSD features should offer subscribers the possibility to use the telecommunications services with

operating comfort in a versatile manner

yield optimal business management results for the operating company

adapt to current needs easily.

So far as feature recommendations or standardizations of ETSI or ITU-T exist, theseare taken into consideration upon the realization of the feature in EWSD.

The offer of features has grown a great deal since the introduction of EWSD. Thistrend continues, following the demands of the market. Here a difference must be

made between the offer of features and the scope of features of an EWSD versiondelivered to a network operator. The actual feature scope of an EWSD versiondelivered to a network operator is the contractually regulated subset of the featureoffer. It is established in a project-specific feature list.

The abundance of EWSD features is subdivided into feature groups:

Interface tosubscriberequipmentfeatures

Analogsubscriberfeatures

Systemfeatures

e.g.

Automatic

Calldiversion

callback

Malicious

Call tracing

as with

analogsubscribers,but in additione.g.

Closed usergroup

Multiplesubscribernumbers

e.g.

analog a/binterface

digital Uinterface

V5interfaces

e.g.

Controlof the systemtime witha radio clock

File transferto the post-processingcenter

Numbering and routingfeatures

Interexchangesignalingfeatures

e.g.Digit translation withconsideration to callingparty attributes(e.g. local area codeof the calling party)

Selection of the routeof a call by meansof fixed alternativerouting or optimizeddynamic routing

e.g. Channel

associatedsignaling suchas MFCR2, E&M...

Commonchannel signalingCCS7 withuser/applicationparts such asITUP, ISUP,SCCP, TCAP,INAP...

Chargingfeatures

e.g. Metering

procedure

Automaticmessageaccounting

Billingbetweennetworkoperators

ISDNsubscriberfeatures

Fig. 2


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GEOcentrex features ADMOSS features

Implementation of exchangefeatures for one group of

subscribers directly connected to

EWSD (CENTREX group) such

as

Common abbreviated

directory number list

Call Pick Up

The possibility to administrate

the database of the CENTREXgroup from one subscriber-

equivalent connected control

terminal

ADMOSS (Advancedmultifunctional operator service

system), with its multifunctional

operator's position (MSB) facilitates

the provisioning of operator

services in the network such as

Directory number information

with immediate forwarding

Language assistance for

international calls

Booking of calls

Setup of large conference

circuits

O&M features

Service handling point tasks for

handling IN features such as

Freephone

Televoting Universal personal

telecommunication

e.g.

Decentralized O&M terminals:

operation and maintenace

terminal (NetM-boot orBCT/BOOT)

Centralized operation via a

network management center

with net manager NetM

Intelligent network features

Fig. 3


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2 EWSD Hardware Overview


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2.1 Mechanical Design

RackrowOne or several network elements of the same or different types can be installed inan installation room. The individual installation units are installed in rows. Such arow is called a rackrow. These rackrows are numbered consecutively (rackrownumber) inside a room to make it possible to find them for maintenance.

Rack

A rack is subdivision within a rackrow. A rack has two doors on both the front andrear side for reaching the HW modules or the cabling of the rack. A rack isidentified by the rack number.

FrameThe frames are located inside the rack. A frame comprises a metal frame as amechanical carrier, plastic shelves on the front side for holding the hardwaremodules, and a multilayer backplane on the back side for the electric connections

within a frame and for plugging the cable to other frames or external equipment. Aframe can hold one or two horizontal rows of modules, depending on the size ofthe backplane. A frame is identified by the so-called mounting unit or MUT. TheMUT serially numbers the individual horizontal sections of a rack from top tobottom.Two types of frames are used in the moment: SIPAC and SIVAPAC. Both typesmainly differ in the structure of the backplane and the plugs.

Module

The HW modules are located within the frame. The module rows within a MUTare identified with the letter A or C in order to facilitate finding the modules even

with frames of several rows. The position of the modules within a module row areidentified by the module location or MOLOC (with SSNC called PITCH), whichis stamped on the metal carriers of the frame.

The entire rear wall cabling is pluggable. The cables are delivered with connectedcable connectors and in the required length.

EWSD installations get their supply voltage (48 V or 60 V DC) from central powersupply systems with battery.


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SIEMENS SIEMENS SIEMENS



SIEMENSSIEMENS SIEMENS D 900

4

EWSD Mechanical Setup

01

02

03

04

05

06

MUT

1

2

3Rack rows

Racks1 2 3

Module location

001 007 013 019 025 031 037 043 049 055 061 067 073 079 085 091 097 103 109 115 121

Module frame

Module

Fig. 4


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2.2 Overview: System Architecture

2.2.1 Overview of Hardware Configurations and SoftwareReleases

Currently EWSD is used in over 100 countries where the hardware configurationsand software releases in the table below are mainly used.

The different HW units are described on the following pages.


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HardwareConfiguration

SoftwareVersion

max. switchedtraffic volume

in ERLANG

Busy Hour

Call Attempts

EWSD CLASSIC

with Common

Channel NetworkController CCNC

with Switching

Network SN A/B

with Remote

Switching Unit RSU

(only V14A / V15)

V11 / V12 /V13A / V14A /V15

up to 25000 more than1000000

EWSD POWERNODE

with Signaling

System NetworkControl SSNC

with Switching

Network SN D

with Remote

Switching Unit RSU(only V15)

V13T / V15 up to 100000 up to 4000000

Fig. 5

TIP

Following additional features can be also used with EWSD SW versions V12I, V13I,V14A and V15:

high bit rate Internet access via xDSL lines

integrated PoP for dial-in users


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2.2.2 Overview: HW Units of EWSD CLASSIC Configuration

EWSD-CLASSIC includes the following HW units which are all equipped with theirown control processors.

Digital Line Unit (DLU)

Digital Line Unit version A/B/D are connected to 2 LTG's via a maximum of four2Mbps. Digital Line Unit version G is connected to 4 LTG's via a maximum of16x2Mbps. Compared with the DLU A/B/D, more subscribers can be connectedhere and a larger traffic volume can be relayed towards the LTGs.By default, ISDN BA and analog subscribers are connected to the DLU. Here theDLU serves as a digital concentrator. Furthermore the DLU can contain a packethub which is used as an interface to the Internet for the High Bit Rate Data of the

xDSL subscribers of this DLU (ATTANE hiA functionality). Line Trunk Group (LTG)

The LTG serves to connect up to four PCM30 systems (2Mbps) which are used toconnect other exchanges, DLU's and PBX's. The individual LTG's are connectedto the duplicated switching network via 8Mbps highways.Furthermore a PoP can be connected to the LTG. Such a PoP takes over theRemote Access Server RAS functions for dial-in users. In case of using aSURPASS hiG1000 as a RAS, we speak about a so called "integrated PoP" with aPA interface to "his" EWSD exchange.

Switching Network (SN A/B)

The SN serves to through connect the individual user channels of the 8Mbpshighways from the incoming LTG's to the corresponding outgoing LTG'S, tothrough connect the SS7 signaling channels to the Common Channel SignalingController and of the messages channels from the LTG's to the CP. The SN isduplicated and can be equipped with a maximum of 504 LTG's. It receives setupcommands from the CP for parallel through connecting in both SN's.

Remote Switching Network (RSU)

The RSU enables the operation of DLU`s and LTG's at a site remote from the hostexchange. The LTG's of the RSU are connected to the Remote Timeslot

Interchange (RTI) which is an RSU internal switching network. The RTI isconnected via PCM30 links to the Host Timeslot Interchange (HTI) in the hostEWSD. The HTI itself is linked by 8Mbps highways to the SN. Calls between twoports of an RSU are normally directly switched in the RTI and not routed via thehost exchange. It is possible to connect the RSU to other exchanges or to anotherRSU of the same host exchange.

Common Channel Signaling Controller (CCNC)

The CCNC ensures the security, message distribution and message routing of theCCS7 messages. It is connected to the SN via a maximum of two 8Mbps highwaysand via this has access to the individual SS7 signaling channels of the PCM30

systems connected to the LTG's. Within EWSD the CCNC communicates with theuser parts in the LTG via the messages channel system.


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Central Clock Generator (CCG)

The CCG synchronizes the clock generators in MB, CCNC, SN, LTG and DLU.This guarantees synchronism between transmitter and receiver on the EWSD

internal 8Mbps highways. In synchronous networks the CCG's of the individualnetwork nodes work with the same clock.

Coordination Processor (CP)

The CP controls the setup of connections (call-processing) and carries outsafeguarding tasks for the entire exchange. Therefore it is connected via theMessage Buffer (MB B) to the control of the SN as well as to the control of theLTG's (via the SN). The MB itself is connected to the SN using 8Mbps highways.Furthermore the CP has a connection to the CCNC control to relay the CCS7messages to the corresponding users in the LTG's and vice versa.The duplicated Magnetic Disk Memory (MDD) and the Magneto-optical Disk(MOD) / Magnetic Tape Device (MTD) are used as back-up memories for thecomplete EWSD software.The CP additionally performs operation and maintenance O&M tasks and offerstherefore interfaces to the local O&M terminals (Basic Craft Terminal). The systempanel SYP is connected to the CP for visual and audible alarming.

Via x.25 links the CP can be connected to a billing Post-Processing Center as wellas to a Network Management Center (with Net Manager NetM).

CCNC

MBCCG

SN

0 & 1

LTG

Partner

exchange

(2Mbps with

trunks & SS7 links)

LTG

LTGDLU

PBX

Main station

subscribers

SIEMENS

NIXDORF

CP

X.25 connections

to NetM and

postprocessing

centers

BCTMDD

MOD

HTIRTILTGDLU

RSU

EWSD CLASSIC

max. 6 CAP

Fig. 6


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2.2.3 Overview: Hardware Units of EWSD POWERNODEConfiguration

Compared with the CLASSIC configuration, the following new HW units are used inthe EWSD POWERNODE:

SN Version D (instead of SN A/B)The SND connects up to 2016 LTG's.

MB Version D (instead of MB B)Serves to distribute the message flow CP-LTG, CP-SND, SSNC-LTG and LTG-LTG.

Netmanager (NetM)The Netmanager is used for local and central operation and monitoring of theEWSD Powernode.

Signaling System Network Control (SSNC) (instead of CCNC)

The SSNC ensures the security, message distribution and message routing of theSS7 messages. This occurs with high capacity and flexibility which meet thecurrent and future demands with respect to message throughput and new features.It primarily provides the protocol functions of the Messages Transfer Part (MTP)and the Signaling Connection Control Part (SCCP, user part for non-user channelrelated signaling applications).

In opposite to the CCNC it is possible to directly connect 2Mbps systems to the

SSNC. These contain either 31 x 64Kbps SS7 channels or one 2Mbps SS7channel (high speed link with ATM protocol)

The SSNC has its own OAM platform. To operate it, it is equipped with V24/LANinterfaces to connect the Net Manager NetM.

Coordination Processor

The CP is connected via an so called ATM bridge processor (AMP) to the SSNC.

The switching efficiency of the CP (BHCA) is considerably better with thePOWERNODE then when used in the CLASSIC configuration. This is becausemessages between LTG - LTG and LTG - SSNC directly passed by the MB D and

are not routed through the CP (CP is not loaded by the EWSD internal messageexchange.


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EWSDPowernode

LTG

LTG

SSNC

MBD

2Mbps with

Trunks and

64kbps SS7 Links

64 kbps orHigh Speed

SS7 Links

207Mb/s

CP

NetM

207Mb/s

LTG

LTG

DLU

SND

Fig. 7


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3 Functional Structure of the Digital Line Unit

(DLU)


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3.1 Function Overview DLU B/D

The DLU is used as a digital concentrator for the connection of subscriberstothe EWSD.

In this paragraph only the connection of analog and ISDN-BA subscribers to the DLUis described. The so called High Bit rate access to the internet via xDSL will bedescribed at the end of the DLU chapter.

3.1.1 Connectivity

Analog connectivity is for:

Main station lines with pulse dialing, pushbutton dialing, call charge display

Coinbox telephones

Small analog private branch exchanges with/without direct-inward-dialing

Digital connectivity is for:

ISDN Basic Accesses

Small digital private branch exchanges

Connection of an access network (AN) via V5.1 interface

3.1.2 Connection Capacity and Expansion Possibility of a DLU

Depending on used module types and required traffic volume:

up to approx. 900 analog subscriber lines or

up to approx. 800 digital subscriber lines (ISDN BA)

up to 32 V5.1 interfaces

Mixture of analog subscribers, digital subscribers and V5.1 interfaces in view of thefact that max. 120 calls can be held simultaneously

Expansion in small modular steps:

Each with an analog subscriber line module (SLMA for 16 subscribers) Each with an digital subscriber line module (SLMD for 16 subscribers)

Each with a subscriber line module (SLMX) for two V5.1 interfaces with 30subscribers each (access network AN)

Note:

The DLU type DLUV can be used as an alternative to SLMX in the standard DLU.Only V5.1 access networks can be connected to a DLUV (max. 10 x V5.1 per DLUV).


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digital

maximum120 user

channels

with 64 kbps

DLU B/D

Concentrationof the subscriber accesses

Analog/digital conversionfor analog subscribers

Modules

SLM for the connection of

a/b interfaces

(SLMAwith 16 subscriberline circuits SLCA)

U interfaces(SLMDwith 16 subscriber

line circuits SLCD)

V5.1 interfaces(SLMXwithtwo V5.1 interfaces)

External interfaces to DLU

Analog 2 wire interface for a/b

connection

Digital 2 wire interface for basic

access (U interface of BA)

2 Mbps PDC

Analog subscribers

Small PSTN PBX

Digital subscribers

Small ISDN PBX

V5.1 interface to the AN

Fig. 8


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3.1.3 Connecting Possibilities of the DLU B/D to EWSD

The DLU is connected to the LTG by a maximum of four primary digital carriers(PDC), whereas a DLU is linked with two LTG as a rule for reasons of availability. Asan exception the HW type DLUV provides up to two PDC which may be regarded asPDC0 and PDC2 in the following text.

The DLU can be used locallyin the exchange or remotelyin the vicinity of thesubscriber.

It is possible to connect the local DLUB to the LTG by two 4096 kbps routesinsteadof four 2Mbps routes.

All features are regardless of whether the DLUB is operated locally or remotely.

Common channel signaling (CCS)

Channel 16 in the first and third PDC is used for the transmission of controlinformation messages between the DLUB and the line/trunk groups (LTG).

Here channel 16 on the first PDC transmits the control information messages for the60 user channels to PDC 0 and 1, and channel 16 on the third PDC the controlinformation messages for the user channels to PDC 2 and 3.

For the local DLU interface, channel 32 on both 4096-kbps connections is used forCCS.

High reliabilityHigh reliability is yielded by:

the connection of the DLUB to two LTG

The duplicating of DLU units with central functions

constant self testing


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PDC3

DLU LTG

LTGDLU

Local applicationPDC0

PDC1

PDC2

CCS

CCS

CCS

CCS

PDC3

PDC0

PDC1

PDC2

Remote application

DLULTG

CCSPDC0

PDC1

60 user channels

one CCS time slot between DLU control DLUC

and LTG control GP

alternative: 1 x 4 Mbit/s for local DLU interface

Fig. 9


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3.1.4 Central Functional Units of the DLU B/D

Control unit for DLU (DLUC)

The control unit for DLU (DLUC) controls the DLU internal functional sequenceand distributes or concentrates the signaling from and to the subscriber linecircuits. For reasons of reliability and to increase the throughput rate, there are twoDLUCs in the DLU. They work independently of each other in load sharing so thatthe one DLUC takes on all tasks should other DLUC fail. Every DLUC isresponsible for two PDC (60 user channels, one CCS).

Each DLUC has access to the processors of all subscriber modules and other DLUfunctional units via the DLU internal control bus. Present messages are cyclicallyrequested of the modules; the modules are selected directly for transfer of

commands and data. Digital interface units of the DLU (DIUD or DIU:LDID)

The DIUD has two interfaces for connecting two PCM30 primary digital carriers(PDC). The PDC link the DLU with the LTG. Symmetrical or coaxial lines can beconnected.

The DIU:LDID has a 4096 kbps interface for connecting a DLU in local use to theLTG. The connection ensues via a symmetrical copper line. With the DIU:LDID,the contents of 60 user channels and of one CCS signaling channel aretransmitted via a single 4096 kbps primary digital carrier (instead of two PCM30primary digital carriers).

The DIUD gathers the control information message from channel 16 of a PDC andrelays it to the DLUC. In the reverse direction, the control information messagescoming from the DLUC are inserted into channel 16 of the same PDC and thentransmitted to the LTG.

With the DIU:LDID, the signaling in channel 32 is transmitted.

Furthermore the DIUD or the DIU:LDID forms the interface between the channelsof the DLU internal 4096 kbps user information network and the channels of the 2or 4 Mbps routes to the LTG. The user information is distributed to the subscriberline modules (SLMs) or relayed from them to the LTG via the 4096 kbps bus.

Test unit (TU)

The TU carries out manual or routine testing of the subscriber lines and subscriberline circuits. No TU is necessary if exclusive use is made of ILTF (integrated linetest function).


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SLM DIUD

DLUC

DLUC

SLM

TU

Controlnetwork 0

0

1

PDC

DLU-System

0

DLU-System

1

2

3

Subscriber

accesses

DLU

DIUD

Control

network 1

User information

network 0

User information

network 1

Testbus

to all SLM

Fig. 10


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3.1.5 Subscriber Line Modules

Subscriber Line Module SLMA

The standard modules for connecting analog subscribers (SLMA:FPE or ILTF-SLMArespectively) have 16 analog subscriber line circuits (SLCA), an SLMCP control unit,and a duplicated interface to the two control and user information bus systems. Theygenerate the ringing current and the charge pulses for the analog telephones.

The SLMA with integrated test function for subscriber lines (ILTF = integrated line testfunction) replaces the SLMA:FPE and the Test Unit (TU). The functions otherwiseperformed by the TU are implemented in the subscriber line circuits (ILTF-SLCA).Therefore no Test Unit (TU) is needed in cases where exclusive use is made of ILTF-SLM.

The ILTF-SLMA is implemented in two variants:

SLMA:ITF (without Metallic Test Access)

SLMA:ITM (with Metallic Test Access)

Special SLMA modules are available for special cases (e.g. connection ofsubscribers via pair gain, connection of non-ISDN exchanges with direct-inward-dialing). If use is made of those special SLMA modules or of SLMA:FPE with externalringing generator, the TU is still needed.


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Analog

subscriber

line Standard SLMA

SLCA

Control part SLMCP

0

15

Control bus 0

(DLUC0)

Control bus 1

(DLUC1)

4096-kbps-bus 0

(DIUD0 or

DIU:LDID0)

4096-kbps-bus 1

(DIUD1 or

DIU:LDID1)

Test bus

(not in case of

ILTF-SLMA)

Battery Supply

Overvoltage Protection

Ringing

Signaling

Coding

Hybrid 2/4-Wire

Testing

Fig. 11


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Subscriber Module SLMD

The standard module for connecting digital subscribers (SLMD:QFB) has 16 digital

subscriber line circuits (SLCD), a control section, and a duplicated interface to thetwo control and user information networks.

Depending on the project specific encoding on the digital 2 wire subscriber line, themodule SLMD:TFB can also be used.

TIPILTF-SLMA can provide for SLMDs the necessary test functions which otherwise areperformed by the TU. This works for the so called ILTF-SLMD (ILTF = integrated linetest function). Therefore no SLMD-modules with integrated ILTF is existing.


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ISDN

subscriber

lines SLMD

SLCD

Control part

0

15

Test bus

Control bus 0 (DLUC0)


4096-kbps-bus 0

(DIUD0 or DIU:LDID0)

4096-kbps-bus 1

(DIUD1 or DIU:LDID1)

Overvoltage protection

Provisioning of the time multiplex interfacewith the 2B and D channel with a total

of 144kbps and the 16kbps for the clock synchronization (layer 1 of the DSS1)

Echo compensation for the bidirectional digital transmission on the 2-wire

subscriber line (layer 1 of the DSS1)

2-wire/4-wire conversion and adaption of the line code used on the subscriber

line (layer 1 of the DSS1)

Separation of the DSS1 signaling messages from the X.25 data packets of the

subscriber (layer 2 of the DSS1)

Protection of the transferof the DSS1 signaling messages in the D channel

(layer 2 of the DSS1)

Test access to the subscriber line/circuit

Fig. 12


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3.1.6 Stand-alone Service of a DLU

If both control units of a DLU lose their signaling channel to the LTG owing totransmission faults (failure of the PDC) or LTG failures, a DLU can continue to workin stand alone service. This feature is as a rule available to all remote DLU. For thisthe DLU must be equipped with a stand alone service control module (SASC-E).

This module assumes the control of the call setup between subscribers of the sameDLU when in stand alone service. The through-connection of the voicecommunication follows internally in the DLU. Metering does not take place.

TIPIf several remote DLU are next to one another, they can be aggregated to a remote

control unit(RCU). Up to 6 remotes DLU are linked to one another for this (inter-DLU connections).

If the individual DLU of an RCU go into stand alone service, calls betweensubscribers on different DLU of the RCU are still possible.

The inter-DLU connections are used in stand alone service only.


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Remote control unit (RCU)

Analog and

ISDN sub-

scriber lines

Links

between

the DLUsof an RCU

DLU1

DLU6

DLU2

DLU4

DLU3

DLU5

LTG

LTG

PDC0

PDC1

PDC2

PDC3

PDC0

PDC1

PDC2

PDC3

with CCS

without CCS

Fig. 13


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3.2 Overview of DLU G Functions

From software release V15 the DLUG can be used as a digital concentrator toconnect subscribers to EWSD. This section only deals with connecting analog andISDN-BA subscribers, the xDSL solutions for high bit rate Internet access are dealt

with in a later section.

3.2.1 Options to Connect to DLU G

There are analog connection options for:

individual connections with pulse dial, key dial, charge display

coin telephones

small analog PBX's with/without extension

There are digital connection options for:

ISDN -

small digital PBX's

the connection of Access Network to PSTN or ISDN subscribers via a V5.1interface (DLUV)

3.2.2 Allocation Capacity and Upgrade Options of a DLU G:

Maximum load: 390 ERL

Depending on module equipping:

up to approx. 2000 analog subscriber lines or

up to approx. 1500 digital subscriber lines (ISDN basic connections)

up to 40 x V5.1 interfaces

Upgrade in small modular steps: each with one analog subscriber line module (SLMA for 32 subscribers)

each with one digital subscriber line module (SLMD for 16 subscribers)

each with one V5.1 line module DLU-V for 10 V5.1 interfaces with 30 subscribersper interface (Access Network AN)


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DLU G

Concentration

of the subscriber accesses

Analog/digital conversion

for analog subscribers

Modules

SLM for the connection of

a/b interfaces

(SLMAwith 32 subscriber

line circuits SLCA)

U interfaces

(SLMDwith 16 subscriber

line circuits SLCD)

V5.1 interfaces

(DLUVwith

ten V5.1 interfaces)

External interfaces to DLU

Analog 2 wire interface for a/b

connection

Digital 2 wire interface for basic

access (U interface of BA)

2 Mbps PDC

Analog subscribers

Small PSTN PBX

Digital subscribers

Small ISDN PBX


Fig. 14


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3.2.3 Options to Connect DLUG to EWSD

The DLU is connected to LTG's via a maximum of 16 primary multiplex lines (PDC),although for reasons of availability, a DLUG is usually connected to four LTG's.

The DLU can be used locally in the exchange or remotely close to the subscribers.

For the local DLU interface it is possible to connect the DLU to the LTG via 4096kbps routes (local digital interface LDI) instead of two 2Mbps routes.

All features are independent of whether the DLU is operated locally or remotely.

Each DLUV module (10 V5.1 interfaces) is connected independently of the other DLUparts via 2 PDC's.

Common Channel Signaling (CCS)For the transmission of control information between the DLU and the line modules(LTG), a 64kbps channel is used by default per LTG which is located in PDC0 timeslot 16.

This channel transmits the control information for all user channels on all PDC's tothis LTG. Here a modified CCS7 protocol is used.

High service reliability

High service reliability results from:

the connection of the DLU to at least two LTG's the duplicating of DLU units with central functions

constant self-testing


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DLUC 1,DLUC:LDI

for local DLUG

or

DLUC30

for remote

DLUG

LTGN

LTGN

LTGN

LTGN

ALEXoption.

SASC-Goption.

MTAoption.

Special 2)

module types

SLMD16DLUG

TS16

TS16

TS16

TS16

(2Mbps) or (4Mbps) per LTG4 x

signaling channel between DLU and LTG for controlling all speech channels

between DLU and LTG

2 x

TS16

Fig. 15


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3.2.4 Central DLUG Functional Units

The DLU controller (DLUC30/DLUC:LDI) controls the DLU-internal functional processand distributes and concentrates the signaling and the user channels from and tosubscriber line circuits. For reasons of service reliability and to increase thethroughput rate, there are two DLUC's in the DLU. They work independently of oneanother in load sharing so that if one DLUC fails the other DLUC take over all tasks.

Connection of the DLU control to the LTG's

DLUC30 to control max. 8 PDC (2Mbps) to 2 LTG'sEach DLUC is responsible for a maximum of 8 PDC's which connect this DLU to 2LTG's. All user channels of maximum 4 PDC's to an LTG are usually controlled byone signaling channel (TS16 of the first PDC).

DLUC:LDI to control max. 4 x 4Mbps to 2 LTG'sEach DLUC:LDI (only local DLU's) is responsible for a maximum of four 4096-kbpsinterfaces which connect this DLU to 2 LTG's. All user channels of maximum two4096 kbps multiplex lines (instead of 4 PCM30 multiplex lines) to an LTG areusually controlled by one signaling channel (transmission in the first 4096 kbpsmultiplex line).

Connection of the DLU control with the DLU subscriber modules

Each DLUC has access to all peripheral DLU modules via the DLU-internal bussystem.The DLU-internal bus systems are routed separately for both DLUC's via the so-

called bus distributors (BD) to the individual SLM's.Each DLUC takes care of one bus system per connected LTG so that eachsubscriber module is connected to both DLUC's via a total of 4 bus systems.However, generally the SLMD modules only have interfaces to two bus systems,therefore subscribers are only served by 2 of the maximum 4 LTG's (normally thefirst LTG at each DLUC).

Control bus:The control bus enables the DLUC to access the processors of all subscribermodules and other DLU functional units. The modules are queried cyclically onexisting messages (e.g. subscriber state change). These messages are relayed to

the relevant LTG via the signaling channel. In the other direction the control busserves to hand over commands and data to the relevant subscriber module. TheDLUC receives these commands via the signaling channel from one of themaximum two connected LTG's.

Payload network:The DLUC continues to form the interface between the channels of the DLU-internal payload network and the user channels of the 2 or 4 Mbps routes to theLTG. The useful information is distributed to the subscriber line module (SLM) andfrom there forwarded to the LTG via this network.The payload network can work with 4 or with 8 Mbps.


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1) up to 4 PCM30 or 2 LDI with 1 CCS /

2) e.g. LTOD, LTCD, COTU etc.

DLUG

DLUC 1,DLUC:LDI

for local DLUG

orDLUC30

for remote

DLUG

DLUC 0,DLUC:LDI

for local DLUG

or

DLUC30

for remote

DLUG

LTGN

LTGN

LTGN

LTGN

1)

ALEXoption.

SLMA32

SASC-Goption.

MTAoption.

1)

Special 2)

module types

1)

1)

SLMD16

Fig. 16

DLUC 0

LTG x 1

LTG x 0

DLUC 1

LTG y 1

LTG y 0

I

O

P

I

O

P

DLU Bussystem

(control & user info)

BDs 0

BDs 1

max.

4 PDC

per LTG

SLMA

(SLMD only

connected toone bus per

DLUC)

Fig. 17


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3.2.5 DLUG Subscriber Line Modules

SLMA subscriber line modules

The standard modules used to connect analog subscribers (SLMA) have 32 analogsubscriber line circuits SLCA, a control SLMCP and four interfaces to the internalcontrol and payload (PCM) networks. Ringing current and call-charge impulses forthe analog telephones are produced on the module. Simultaneously they contain therequired hardware for internal/external testing of the connected subscribers.

There are three variants of the SLMA:

SLMA:ITFG (subscriber check via EWSD)

SLMA:ITMG(with Metallic Test Access for external subscriber check)

SLMA:ITHG (with Metallic Test Access and increased power supply for cointelephones)


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39

Port 0

Port 31

.

.

.

.

SLICsubscriber line

interface circuitSLMCP

FEprom

feeding-

interfacePowersupply

DC- DCconverter

overvoltage protection

2/4 wire

line feeding

ringing and metering

analog/digital conversion

testing

SLMA:ITFG

2x PCM-busto DLUC0

2x PCM-bus

to DLUC1

2x Control-bus

to DLUC0

2x Control-bus

to DLUC1

Fig. 18


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Subscriber Module SLMD

The standard module for connecting digital subscribers (SLMD:QFB) has 16 digital

subscriber line circuits (SLCD), a control section, and interfaces to two control andpayload (PCM) networks (one per DLUC only).

Depending on the project specific encoding on the digital 2 wire subscriber line, themodule SLMD:TFB can also be used.

TIP

ILTF-SLMA can provide for SLMDs the necessary test functions which otherwise areperformed by the TU. This works for the so called ILTF-SLMD (ILTF = integrated line

test function). Therefore no SLMD-modules with integrated ILTF is existing.


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41

ISDN

subscriber

lines SLMD

SLCD

Control part

0

15

Test bus

(not in case of

ILTF-SLMD)



4096-kbps-PCM bus 0

(DLUC0)

4096-kbps-PCM bus 1

(DLUC1)

Overvoltage protection

Provisioning of the time multiplex interfacewith the 2B and D channel with a total

of 144kbps and the 16kbps for the clock synchronization (layer 1 of the DSS1)

Echo compensation for the bidirectional digital transmission on the 2-wire

subscriber line (layer 1 of the DSS1)

2-wire/4-wire conversion and adaption of the line code used on the subscriber

line (layer 1 of the DSS1)

Separation of the DSS1 signaling messages from the X.25 data packets of the

subscriber (layer 2 of the DSS1)

Protection of the transferof the DSS1 signaling messages in the D channel

(layer 2 of the DSS1)

Test access to the subscriber line/circuit

Fig. 19


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3.2.6 Emergency Operation of a DLU G (Stand-alone Service)

If both DLUC lose all their signaling channels to the LTG because of transmissionerrors (PDC failure) or LTG failure, a DLU can continue to work in emergencyoperation (stand alone service). This feature is usually available to all remote DLU's.The DLU must be equipped with an emergency operation control module SASC-G.

In emergency operation, this module takes over the control of setting up a connectionbetween subscribers of the same DLUG. Voice connections are through connectedinternally in the DLU. Calls are not metered. There is no connection to subscribers atother DLU's.


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LTGSLM

SLM

D

L

U

C

SASC Gcontrol

LTG

LTG

LTG

A

Btraffic

Fig. 20


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3.3 xDSL Interfaces at EWSD DLU

Subscriber modules which provide xDSL subscriber line interfaces can also beintegrated into a DLU. The administration of these modules require the NetM.

Such a DLU is then called a hiA7100 which belongs to the ATTANE product family.

The xDSL technology provides the subscriber simultaneously with

high bit rate Internet access

normal POTS or ISDN connections to other analog or digital subscribers

The POTS / ISDN connections of the xDSL subscriber are routed to an LTG as withother analog / digital EWSD subscribers via the DLU-internal control and payloadnetwork and the DLUC.

With high bit rate Internet access the useful information must by contrast be handedover directly from the DLU into the IP network of the Internet Service Providers ISP.This means, here is no circuit-switched connection setup by EWSD towards a Pointof Presence PoP of the ISP as is the case with conventional remote dial-in users.Therefore neither the DLUC of the DLU nor any other EWSD system unit is loaded bythe data transfer of these high bit rate accesses.

The DLU must be upgraded by three components to become a hiA7100:

Packet Hub SLMI:PHx with interface to the ISP's packet network

The Packet Hub offers access to the ISP's data network for maximum 14 xDSLsubscriber modules. Here the Packet Hub supports the following interfaces towardISP: Ethernet, Frame Relay or ATM.

DLU-internal ATM connection between the individual xDSL subscriber modulesand the Packet Hub

These connections are implemented individually for each xDSL subscriber moduleeither using plug-in cable (front side of the subscriber module for the front side of thePacket Hub) or via the backplane of the DLU.

Subscriber modules with xDSL interfaces SLMI:FMxfor 8 subscriber lines with ADSL.Lite Protocol:

For each subscriber, a POTS connection (analog telephone) and a high bit ratedata connection (PC with ADSL.Lite network interface card NIC) cansimultaneously exist through EWSD to the ISP. The following maximum bit ratesapply to the data connection: downstream 1.5 Mbit/s, upstream 512 kbit/s

SLMI:AMxfor 8 subscriber lines with ADSL protocol:For each subscriber, one POTS or 2 ISDN connections through EWSD and a highbit rate data connection to the ISP can exist simultaneously. For the POTS / ISDNconnections, another SLMA / SLMD is currently required in the DLU in addition to

the SLMI:AMx module.


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The following equipment is required at the subscriber side:

a) ISDN terminal equipment connected to the NT BA or analog telephone for thecircuit-switched connections through EWSD

b) PC with Ethernet interface connected to an ADSL NT or PC withintegrated ADSL network interface card NIC for high bit ratedata connection to the ISP

c) NT splitter as termination of the ADSL line at the subscriber. NT BA or ananalog telephone as well as ADSL NT or ADSL NIC are connected to thissplitter

The following maximum bit rates apply to the data connection:downstream 6 Mbit/s, upstream 640 kbit/s

High Bit Rate Data Services

in DLU used as hiA7100DLU

ADSL

ADSL.Lite

Micro

filter

Voice

Splitter

ADSL.Lite

(HBR data

plus

POTS)

NT BA

SLMI:FMx

SLMI:AMx

+ SLMA/D

SIEMENSNIXDORF

SIEMENSNIXDORF

SIEMENSNIXDORF

DLU System

Packet

Hub

HBR data

via ATM

Voice via

DLU Bus

to

LTG

to ISP via

ATM/FR/

Ethernet

ADSL

(HBR data

plus

POTS/BA)

ADSL NT

Ethernet

Fig. 21


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4 Functional Structure of the Line Trunk

Group (LTG)


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4.1 External 2 Mbps Interfaces to LTG

for the connection of digital trunks with CAS signaling from/to nodes of the PSTN for the connection of digital trunks from/to nodes of the ISDN, for the connection of

CCS7 signaling channels from/to nodes of the ISDN or central databanks such asthe service control point (SCP) of the IN

For the connection of large PSTN private branch exchanges with CAS signaling

for the connection of large ISDN private branch exchanges, intelligent peripherals(IP) of the IN, or packet handlers of a X.25 packet network (PSPDN) by theprimary access (PA) with DSS1 signaling

Connection of access networks with PSTN or ISDN subscribers by V5.2 interface

Connection of local or remote DLU


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LTG

4x

2 Mbps

PDC

Digital trunks with CAS

Digital trunks and CCS7

signaling channels

PABX lines with CAS

PABX lines with DSS1 (PA)


DLU

External 2 Mbps interfaces

Fig. 22


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4.2 Function Overview LTG

The line trunk group (LTG) forms the interface between the digital environment of thenode and the digital switching network (SN).

Connection to the duplicated switching network:

8Mbps SDC with 128 time slots

(If the LTG is part of an RSU the SDC are connected to the RTI of the RSU. The RTIitself is connected to the SN via the so called HTI.)

Function of the LTG:

The LTG take on decentralized control tasks for reducing the load on the coordinationprocessor (CP).

The LTG communicate with the CP / SSNC or CCNC / other LTG via messagechannels (MCH) for this.

The LTG always sends and receives the speech information via both switchingnetworks (SN0 and SN1).

However the LTG only relays the speech information from the active switchingnetwork outward. The other SN is designated as inactive. The LTG can immediatelysend and receive the current user information with it in case of a fault.


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Call processing:decentralized controltasks for call setup toreduce the load of the CP

Interface conversionbetween duplicated SNand the digitalenvironment of the node(through-connectionof the user information)

LTG

SN0

SN1

8Mbps SDC

8Mbps SDC

PDC 3

PDC 2

PDC 1

PDC 0

Signaling to other nodes, DLU/subscribers and PBX:

- Generation of signaling messages to be sent

upon initiative of the CP

- Pre-evaluation of received signaling messages and

relay to the CP

Communication via the message channelswith:

- the CP

- the SSNC / CCNC

- other LTG

Generation of audible signaling tones for the subscriber (tone

generator) and evaluation of the DTMF dialed digits (code receiver)

Call processing tasks of the LTG

Fig. 23


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4.3 LTG Functional Types

In order to optimally realize various line types and signaling systems, several LTGfunctional typeseach with specific application programsare available.

These various functional types of the LTG SW determine the connecting capabilitiesto an LTG.

Different types of LTG frames exist simultaneously.

The table opposite shows which LTG software functional type is compatible withwhich hardware implementation.


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LTG

Software Functional Type

Compatible

LTGHW - Type

Funktional type B

can be applied to connect:

DLU

PBX

Intelligent peripheral

Packet handler of a X.25 packet network

V5.2 Access Network (only to LTG M/N )

LTG G/M/N

Funktional type C


Trunks with CAS signaling

Trunks with CCS7 signaling

CCS7 signaling channels

LTG G/M/N

Funktional type D


International trunks with echo suppression /

No5 signaling

LTG D

Funktional type H

Frame handler for (de)concentration of X.25

data packets from ISDN subscribers

LTG H

Fig. 24


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4.4 Functional Units of the LTG

Group processor (GP)The GP converts signaling messages of the connected nodes/DLU/PBX into theEWSD intra-system message format and controls the functional units of the LTGvia the signal highways (SIH).

The GP communicates with the CP, the SSNC/CCNC, and other LTG via theduplicated message channel (MCH).

Group switch GS

The group switch realizes the following at the instigation of the GP:

The through-switching of individual speech channels between the PDC and the

SDC with and without attenuation.

The interconnection of tones of the TOG and of code receivers to the userchannels of the PDC.

The formation of three-way conferences

The link to the LTU is realized by speech highways(SPH), the link to the SN bythe LIU.

Link interface unit (LIU)

The LIU serves to connect the LTG to the duplicated SN (SN0 and SN1) via an 8

Mbps SDC each. Code receiver (CR)

The code receiver (CR) of the signal unit makes DTMF/MFC signaling for the callprocessing SW of the LTG available.

The essential tasks are

a) Reception and detection of multi-frequency signals (DTMF, MFC-R2, MFC-R1,CTC)

b) Report of detected signal to the GP

Tone generator (TOG)

The tone generator (TOG) of the signal unit centrally generates the necessaryaudible signaling tones for subscribers and the frequencies necessary for the MFCsignaling.


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Line trunk unit (LTU)

The line trunk unit (LTU) adapts the connected lines to the internal interfaces ofthe LTG and equalizes delays (synchronization of nodes and line bit rate).

The digital interface units (DIU)serve to this purpose (connection of PDC or 4Mbps routes of local DLU).

In addition, the LTU can also include modules with special functions such as testequipment for trunks or an individual announcement system.

DIU

Specialmodule

DIU

GP

SPH

SPH

SPH

8Mbps

SPH

Signal Unit

CR / TOG

SIH

PDC

PDC

SIH

SIH

LTU GS LIU

Speechroute

EWSDinte

rnalmessageexchange

S

N

0

S

N1

Fig. 25


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5 Functional Structure of the Remote

Switching Unit RSU


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5.1 Function Overview

The RSU enables the operation of up to 50,000 subscribers with DLU`s and LTG's atone of the sites remote from the host exchange. The connection from the hostexchange to the LTG's of the RSU is realized from the switching network (host) viathe Host Timeslot Interchange HTI via PCM30 with Interface Trunks to the RemoteTimeslot Interchange RTI.

The heart of the RTI is a switching network which should be considered an extensionof the host switching network. Connections between Subscriber-, trunk- or PBXLine-ports connected at the same RSU are directly switched in the RSU switching network

without having to route the connection via the host exchange.

It is possible to connect the RSU via Backdoor trunks to other exchanges or via

Sidedoor trunks to another RSU (the same host exchange).In the event of a fault (e.g. failure of the host exchange or failure of the transmissionroutes from the host exchange to the RSU), RSU enables stand-alone operation.This means that calls between subscribers of an RSU are possible.


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Interface

trunks

Interface

trunks

Sidedoor trunks

Backdoor

trunks

HTI Host timeslot interchangeRSU Remote switching unitRTI Remote timeslot interchange

Other exchange Other exchange

SNSN

CP

DLU

LTG

HTI

LTG

EWSD RSU

LTG

DLU

EWSD RSU

LTG

DLU

Backdoor

trunks

RTI

RTI

CCNC/SSNC

EWSD host exchange

Fig. 26


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5.2 RSU Functional Units

Each HTI and RTI is internally duplicated with the exception of the interface moduleDIU240 (Plane 0 and 1 of HTI / RTI). The essential functional units of HTI and RTIare:

TSI (AMUX and TSIM)

The core of the HTI/RTI is the TSI (Time Slot Interchange) unit which consists of theAMUX modules (0 to 7) and the TSIM module. The TSI forms the switching networkin the RSU with a matrix 128 x 8 Mbit/s.

MH module

The message channels (MCH) between the LTG's and the host message buffer areadministered in the HTI/RTI by the MH modules. The message channels have theirown transmission protocol (High Speed Link HSL) for transmission on the interfacetrunks. Each MH module administers 16 MCH the individual MH modules togetherform an MH pool.

RSUC module

The RSUC module is responsible for controlling the HTI/RTI. It communicates withthe host CP in a similar manner to the CP with the GP (Group Processor) of the LTG.The RSUC module communicates internally with the TSI and MH modules for

connection setup, connection release and OA&M.

DIU240 module

The interfaces module for the interface trunks/sidedoor trunks is the DIU240. EachDIU240 has 8 x 2 Mbit/s interfaces. Each DIU240 is connected to both redundantsystem halves (plane 0 & 1) of their RTI and HTI.


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plane0

plane1

SN 0

SN1

HTI

L

T

G

TSI

TSI

M

H

M

H

R

S

U

C

R

S

UC

MH MH

RTI

TSI

TSI

M

H

M

H

R

S

U

C

R

S

UC

MH MH

DIU

240

DIU

240

DIU

240

DIU

240

Fig. 27


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5.3 RSU Capacity Stage

Maximum number of HTI on a host EWSD

Up to 32 HTI can be connected to a host exchange. The maximum value of the HTI isdifferent according to switching network type:

SNA/B = 8 HTI

SND = 32 HTI.

Maximum number of RTI / remote LTG per HTI / host EWSD

Per HTI it is possible to connect maximum 14 RTI.In total however a maximum of 254 RTI and therefore 254 RSU can be connectedto a host EWSD.

Up to 71 remote LTG's can be connected to a HTI via the maximum 14 differentRTI's (RSU).

All remote LTG's in the host exchange must have their own 8Mbps interfacebetween switching network and the supporting HTI. In addition the RSUC of theHTI requires its own 8Mbps highway to the SN.Therefore it is not possible using RSU to exceed the maximum number of LTG'spre-specified by the switching network size of the host EWSD.

RSU module frames

The module frames are housed in a rack together with LTG's. Depending on thenumber of the connected LTG's and according to the expected traffic load, in additionto this basic frame, up to three extension frames with additional MH, DIU240 and

AMUX are required. A frame always contains the identical modules for both planes ofRTI / HTI.


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Interface

Trunks

CP

DLU

LTG

LTG

TSIM +

AMUX

RTI

RSU

Host Exchange

RSUC

MH

DIU 240

DIU 240

LTG

DIU 240

SN

RSUC

MH

DIU 240

DIU 240

DIU 240

HTI

Interface

Trunks

to other

RSUs

Sidedoor

Trunks

to other

RSUs

up to

71 LTGs

up to

24 DIUs

up to

192 PCM30

(E1 links)

up to

24 DIUs

1 ... 14 RSU per HTI

(max. 71 LTG per HTI)

up to 8 HTIs with SN A/B

32 HTIs with SN D

up to 254 RSU

per EWSD Host

TSIM +

AMUX

Backdoor

Trunks

Fig. 28


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5.4 RSU Emergency Operation

If an RTI looses all signaling channels to the host owing to transmission errors (PCMfailure) or HTI/host total failure, the RSU can continue working in emergencyoperation (stand alone service).

In emergency operation, this RTI tasks over controlling the connection setup betweenall subscribers connected to this RTI. The voice connection is through connectedinternally in the RTI (TSI).

During stand alone operation no charge registration is performed.

Call set ups via sidedoor trunks or via SS7ISUP backdoor trunks are not possible.Only connections between 2 subscribers of the same RSU and connections viaspecially administered "default backdoor trunks with CAS signaling" are set up.


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RSU

DLU

LTG

Host

DLU

LTG

possible trafficpaths

Signaling

LTG

predefined CAS-

backdoor trunks

or PAslave

CSS7

backdoor

tunks

LTG

sub-

scriber

sub-

scriber

sidedoor

trunks

Fig. 29


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6 Functional Structure of the Switching

Network (SN)


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6.1 Internal EWSD Interfaces on the SN

The internal interfaces from LTG, HTI, CCNC and MB to the SN are implementedusing Secondary Digital Carrier SDC with 8Mbps (the SSNC has no direct interfaceto the SN).

Here the SN serves to establish the transient bi-directional through connecting ofdata of a 64kbps connection between two LTG's (payload) and also to the semi-permanent through connecting of the 64kbps message channels MCH to exchangeinternal messages between the LTG, SSNC/CCNC and CP.

The CP and SSNC have access to this internal message channel system via the MB.(The CCNC of EWSD Classic has access via the CP.)

The processor of each LTG (Group Processor GP) uses the time slot 0 on the SDC

to the SN as its message channel.

In the case of the RSU the interfaces on the SN and the LTG are as described. Onlybetween HTI and RTI are the SDC implemented in several 2Mbps PCM.


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Collection of the MCH

from the various LTGCP

Time slot 0:

Message channel (MCH) between

LTG and MB (semipermanent through-connection)

for communication between LTG/CP/SSNCorCCNC

Time slot 1-127:

Used for the transient

through-connection of the calls

between two subscribers/trunks

LTG

LTG

MB

SN

2 Mbps PDC

8 Mbps SDC

SSNC

CCNC

or

Fig. 30


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6.2 Function Overview SN

The switching network SN is the link within a node for: User channel connections between the LTG (temporary through-connections)

the EWSD internal message exchange between the controls of the LTG,SSNC/CCNC, and CP via the fixed message channels (MCH)

the CCS7 signaling messages between the CCS7 signaling channels on the PCMroutes connected to the LTG and the SSNC/CCNC (by MML commandestablished nailed-up connections NUC, in case of SSNC the NUC is establishedvia a so called "inward LTG").

The switching network is completely duplicated (SN0 and SN1). All calls are always

simultaneously through-connected through both SN, whereas the LTG only though-connects the user channel information coming from the active SN to the PCM routes.If the active SN fails, the other SN (stand-by SN) is switched to without any loss.

The through-connection in the SN B takes place according to the time - space - timeprinciple (change of the time slot, change of the highway, change of the time slot), inthe SN D a so called switching matrixis used. Every through-connectionguarantees in both cases a transparent bi-directional 64kbps path through the SN.

Sequence for the temporary through-connection of the circuit connections:

The CP call-processing programs look for a free call path in the software switching

network image of the CP database from the LTG of the calling party to the LTGof the called party, for instance.

CP issues setting instructions to the control units of the SN for through-connectingthe calculated call path.

The SN - control units execute the setting instructions in the responsible modules.The call path from the LTG of the calling party through the SN to the LTG of thecalled party is thus through-connected.

Afterward the call-processing programs start a call path through-connection testoutgoing from the A-LTG (cross office check COC) in order to check whether theperformance of the call path through the SN is free of fault.

Along with the temporary through-connections (transient connections), there are alsothe semi-permanent connections:

The nailed up connections (NUC) set per MML command

The through-connection (set by the CP software) of the message channelsbetween the control unit of the LTG and the message buffer (MB)


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LTG

LTG

CCNC

MB

User channels between 2LTG

EWSD internal messages

between LTG, SSNC/CCNC,

and CP (message channels)

Control

CP

Setting

instructions

Message

channels

of all LTG

8 Mbps

Switching moduleshandling

SN 0 & SN 1EWSD-CLASSIC

SN A or SN B

SSNC

Fig. 31


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6.3 SN B (EWSD-CLASSIC)

6.3.1 Functional Units of the SN

The SN is offered in various increments. Except for the small switching networks formax. 31 or 63 LTG (combined space-time stages), the SN comprise the subdivisionstime stage group (TSG) and space stage group (SSG).

Time stage group (TSG):

Every time stage group serves to connect the SDC to/from the LTG, the CCNC,and the MB (together with max. 64 of this SDC). An SN can consist of a maximumof 8 duplicated TSGs.

There is a switch group control (SGC) in every TSG which is connected to the CPby means of an own SDC via the message buffer (MB). The SGC receives thesetting instructions for the temporary or permanent bi-directional 64 kbps through-connection from the CP. The SGC realizes the through-connection by setting theindividual time stage modules (TSM) of a TSG. Every TSM can change theposition in time and space of any time slot in any manner for a group of 8connected SDC in a TSG.

The following types of SDC differentiate:

SDC:LTG, secondary digital carrier between SN and every LTG for the circuitconnections (time slots 1-127) and for the message exchange between the LTG

control unit GP and the CP (message channel to time slot 0).

SDC:CCNC, one or two secondary digital carrier for through-connecting the CCS7messages between CCNC and the signaling channels on the PCM routes to theLTG.

SDC:TSG, a secondary digital carrier between SN and MB for relaying themessage channel of all LTG of this TSG to the CP.

SDC:SGC, a secondary digital carrier between the control unit SGC of this TSGand the MB for relaying the setting instructions of the CP to the TSG.

Space stage group (SSG):

The SSGs serve to through-connect the calls between TSMs in the same or indifferent TSGs. An SN can consist of a maximum of 4 duplicated SSGs.

There is a switch group control (SGC) in the SSG which is connected to the CP viathe message buffer (MB). The SGC receives the setting instructions for thetemporary or permanent bi-directional 64 kbps through-connection from the CP.The SGC realizes the through-connection by setting the individual space stagemodules (SSM) of an SSG. Every SSM can change the highway of the time slot forall connected SDC in any manner.


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The individual TSGs and SSGs are connected to one another by SDC:SSG. Here theTSGs and the SSGs of the same switching network (SN0 or SN1) normally worktogether. In the case of an error, a TSG of SN0 can work together with an SSG of

SN1, for instance. This possibility of protection switching grants the duplicated SN avery high failure security.

SDC

time slot y

TSM

SDC

Time Stage module TSM

time slot x

time slot x

SSM

time slot x

Space Stage module SSM

TSG0-0LTG0-x

CCNC

MB

CP

SGC

TSM

TSM

SSG0-0

SGC

SSM

SSM

TSG0-7

SGC

TSM

TSM

SSG0-3

SGC

SSM

SSM

Setup of an SN (example: SN0)

Fig. 32


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6.3.2 Capacity Stages of the SN

Since the SN is offered in many capacity stages, the actual size of the SN can beadapted to the expected amount of traffic of an exchange. Here the traffic to bethrough-connected measured in Erlang as dimensioning sizes is to be observed.

Remark:

Except the beside shown capacity stages there are also offered a SN for 31LTGanda SN for 63 LTG.

Notes on capacity/ space requirements of the SN capacity stages

For the given values, the highest technically possible values are concerned.

If a CCNC is connected, 1 to 2 SDC:CCNC is added depending on the number ofthe CCS7 signaling channels and the number of SDC:LTG reduces accordingly.

Space requirements in the rack:

Every TSG needs only one frame in the rack.

Every SSG needs only a half of a frame in the rack.

The remaining space in the rack can be used for LTG.

a) A maximum of 4 LTG frames can be additionally mounted in a rack for TSG.

b) A maximum of 3 LTG frames can be additionally mounted in a rack for SSG.

c) A maximum of 4 LTG frames can be additionally mounted in the rack of theSN:63LTG.

d) The SN:31LTG is put in the rack of the CP.


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TSG

0.0

TSG

1.0

TSG

0.1

TSG

1.1

SSG

0.0

SSG

1.0

SN:126LTG

SN0

SN1

SN:252LTG

TSG

0.0

TSG

1.0

TSG

0.1

TSG

1.1

TSG

0.2

TSG

1.2

TSG

0.3

TSG

1.3

SSG0.0

SSG0.1

SSG1.0

&

SSG1.1

SN0

SN1

SN:504LTG

SSG0.2

&

SSG0.3

SSG1.2

&

SSG1.3

SSG0.0

&

SSG0.1

SSG1.0

&

SSG1.1

TSG

0.7

TSG

1.7

TSG

0.6

TSG

1.6

TSG

0.5

TSG

1.5

TSG

0.4

TSG

1.4

TSG

0.3

TSG

1.3

TSG

0.2

TSG

1.2

TSG

0.1

TSG

1.1

TSG

0.0

TSG

1.0

SN0

SN1

SN for

max.126 LTG

SN for

max.252 LTG

SN for

max.504 LTG

Traffic (ERL.) 6300 12600 25200

Number of subscribers with

pure local exchange60000 120000 240000

15000 30000 60000

Ratings

Number of trunks with

pure transit exchange

Fig. 33


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6.4 SN D (EWSD-POWERNODE)

6.4.1 Functional Units of the SN D

The SND is a completely new switching principle based on a single-stage switchingmatrix (grate-like matrix) compared to SNB. Here the "time-space-time" structure isno longer used. To ensure a particularly high level of reliability, SND is completelyduplicated.

SND is based on two types of frames

Frame SwitchingNetworkMUltipleXer (F:SNMUX) and

Frame SwitchingNetworkMatrix (F:SNMAT).

A multiplexer and a demultiplexar are provided for the existing environment withF:SNMUXA which bundle 2 x 64 x 8 Mbit/s LTG lines to two optical lines connectedto F:SNMAT. Switching is implemented by F:SNMAT.

In smaller exchanges (up to 252 LTG's) F:SNMUXA can execute switching by itself(without SNMAT). Here the two required SNMUX's (per SN side) are connecteddirectly to one another using the optical lines.

To connect the SND with the co-ordination processor CP, an MBD messagedistributor is required.

The following interfaces can be differentiated:

SDC:LTGSecondary multiplex line between SN (SNMUX) and each LTG for the userchannel connections (time slots 1-127) as well as for the message exchangebetween the LTG control GP and the CP (Message Channel on time slot 0). TheSDC:LTG are identical to the SDC:LTG at the SN B.

SDC to the MBDH in the MB DSecondary multiplex line between SNMUX and MBDH to relay the messagechannel of half of all LTG's of this SNMUX to the CP. This corresponds to theSDC:TSG in the SN B.

MBD-SxSecondary multiplex line between the control module in SNMUX / SNMAT and theMB-D to relay the setting instructions of the CP to the switching network.


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LTG 0-1

LTG 0-63

LTG 1-1

LTG 1-63

SNMUX

0

LTG 30-1

LTG 30-63

LTG 31-1

LTG 31-63

SNMUX

15

SNMAT

CP

MBD

.

.

.

. . .

.

.

.

.

.

.

0

1

0

127

30

31

0

127

8 Mbit/s

SDC-interface

920 Mbit/soptical interface

920 Mbit/s

optical interface

2 x MBD-S1 1 x MBD-S3

(1 x MBD-S3

only with SN252 LTG)

920 Mbit/s

optical interface

920 Mbit/s

optical interface. . .

. . .

. . .

MBDH

2 x MBD-S1

Fig. 34


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6.4.2 SN D Capacity Stages

max.number ofLTG

DE-TYPE max.numberofSNMUXper SNside

SNMAT-per SNside

TrafficErl

252 DE6.0 2 0 12600

252 DE6.1 *) 2 1 12600

504 DE6.2 4 1 25200

756 DE6.3 6 1 37800

1.008 DE6.4 8 1 50400

1.260 DE6.5 10 1 63000

1.512 DE6.6 12 1 75600

1.764 DE6.7 14 1 88200

2.016 DE6.8 16 1 100800*)use DE6.0 instead of DE6.1 if not more thane 252 LTG areplanned (because DE6.0 does not require an SNMAT).

Fig. 35 Capacity stages of SN D


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F:SNMUXA 0

F:SNMUXA 1

F:SNMUXA 0

F:SNMUXA 1

F:SNMUXA 0

F:SNMUXA 1

F:SNMUXA 0

F:SNMUXA 1 F:SNMAT 0

F:SNMAT 1

0 1 2 15

F:SNMUXA 0

F:SNMUXA 1

F:SNMUXA 0

F:SNMUXA 1

F:SNMUXA 0

F:SNMUXA 1

0 1

SN D - DE6.0

for 126 LTG

SN D - DE6.0

for 252 LTG

SN D - DE6.8

for 2016 LTG

Fig. 36


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7 Functional Structure of the Coordination

Processor (CP)


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7.1 Function Overview CP

The CP coordinates the work of the individual EWSD system units. For call processing, the CP assumes the central tasks for a call setup. In the

course of this, LTG and the SSNC/CCNC reduce the load on it.

For operation and maintenance, the CP makes the interfaces available for theman-machine dialogue (input of commands, output of messages and alarms) andto the mass storage devices (magnetic tape/magnetic disk).

For safeguarding, the CP assumes the master-function for monitoring the EWSDhardware and software.


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Call processing: Digit translation Routing Zoning Path selection through the

SN

Charging

Traffic data administration Network management

Operation & maintenance: Input and output from/to

external memories (EM)

Communication with thelocal and central O&Mterminals for the purposeof administration of the

database Alarm indication

CP113C / CP113CR

Safeguarding:

Self-supervision

Supervision of all EWSD functional units

Fault detection

Fault analysis

Fig. 37


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7.2 System Features of the CP113

CP types:

the coordination processor 113C (CP113C) or

the coordination processor 11CR (CP113CR) as a special version for use inrural/container exchanges

The primary features of a CP113C/CR are:

Application of a modular multiprocessor system with combination of task and loadsharing

adaptability to different exchange sizes:

The performance is dependent on the capacity stage, with CP113C more than1,500,000 busy hour call attempts (BHCA).

(The effective, dynamic call setup performance depends on the available featuresand the actual call-mix. They must be individually specified for every time in use.)

Redundancy by duplication of major functional units and pool formation with thecall processors

Use of high performance microprocessor types (processing width of 32 bit/addressing capacity up to 4 Gbytes)

Common memory with a capacity of (at present) 64 Mbyte to 1024 Mbyte (1Gbyte)(used chip at present: 16 Mbit DRAM)

Local memory per processor with a capacity of max. 64 Mbyte (used chip atpresent: 16 Mbit DRAM)


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Input/output processors to:

EWSD functional units

Mass storage devices

Local O&M terminals for manual Boot

NetM

Post processing center

Interfaces of the CP

High-performance multiprocessor system with

32 bit processing width

More than 4,000,000 call setups per hour

Security redundancy of the central units

Modular expandable hardware

(number of processors and memory size)

System features of the CP

Fig. 38


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7.3 Functional Units of the CP

By adding functional unit of the same type, it is possible to expand the basic capacityof the CP113C, depending on necessity. This applies both for the arithmetic andstorage capacity and for the connection of call processing and administrativeperipherals.

Base processors (BAP)

One of the two base processors is operated as master (BAPM) and the other asspare (BAPS). The BAPM handles the administrative tasks and in addition callprocessing tasks proportionally. The BAPS handles only call processing tasks. If theBAPM fails, the BAPS becomes master and assumes the administrative tasks(active/stand-by redundancy for the administrative tasks).

Call processors (CAP)

The call processors (CAP) of the CP113C exclusively handle call processing tasks.They work in according to the load sharing principle. The CAP generate a poolredundancy for call processing tasks together with the BAPS and BAPM in that onemore processor is available than required for the fulfillment of the nominal callprocessing handling capacity (n + 1 redundancy). The CP113C can thereforecontinue to produce the full nominal load even if one processor (BAP or CAP) fails.

With EWSD CLASSIC the maximum number of CAPs is 6 while with EWSDPOWERNODE you can have up to 10 CAPs in the CP.

Input-output controls (IOC)The IOC each generate a common interface to bus B:CMY for max. 12 in-outputprocessors (IOP) via bus B:IOC. The input-output controls (IOC) and the connectedinput-output processor (IOP)for the connection of administrative/datacommunication devices (e.g. input device, mass storage device) and the peripheralEWSD system units (e.g. LTG/SN

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02 Sn2cvxzv010eu13sn 0002 System Overview Ewsd

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