ewsd intro

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AN

INTRODUCTION

TO

SEIMENS

EWSD SWITCH

13-01-2010 1

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INTRODUCTION TO THE EWSD SYSTEM

The EWSD system is divided into different functional areascalled subsystems coordinated by a central system

Each subsystem having its own microprocessor controlexample: Group Processor in the LTG (Line /Trunk Group)

in the functional area of Access.

They may be divided into the following units

Control

Switching Signaling

Access

Power

2

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EWSD SYSTEM LOGICALLY LOOKS LIKE THIS

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CONTROL

Control belongs to the area which is responsible forthe coordination of the various subunits. Control

consists of the following:

Coordination Processor (CP)

Message Buffer (MB) System Panel (SYP)

Central Clock Generator (CCG)

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CONTROLCOORDINATION PROCESSOR

The CP performs the following functions in anetwork node:

Call processing

Operation and maintenance

Safeguarding

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CONTROL

MESSAGE BUFFER

The task of MB is to control the exchange of messages

between the following subsystems:

Coordination Processor (CP) and line/trunk groups(LTG): Commandsand Messages

CP and switch group controls (SGC) of the switchingnetwork: Setting commands for the SN

LTGs among one another: Reports LTGs and the common channel signaling network control

(CCNC):Orders

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CONTROL

CENTRAL CLOCK GENERATOR

In order to switch and transmit digital information,the sequence of operations must be synchronousthroughout the equipment involved.

This requires a clock supply with a high level ofreliability, precision and consistency for all thenodes in the digital network.

This task is fulfilled by the central clock generator(CCG).

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CONTROL

SYSTEM PANEL

The purpose of the system panel is to display

alarms and advisories of internal and externalsupervisory units outside the system) both visuallyand acoustically.

It is divided into two parts namely the SystemPanel Control and the System Panel Display unit.

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SWITCHING

By virtue of its high data transmission quality, theswitching network can switch connections for

various types of service (for example telephony,facsimile, teletext, data transmission).

This means that it is also ready for the IntegratedServices Digital Network (ISDN).

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SWITCHING

(CONTINUED)

Duplicated (full redundancy)

Highly-Integrated switching network modules

One space stage module can handle up to 1024

simultaneous calls with full redundancy Interfaces of 8,192 Kb/s available within

Highly compact design from space-saving point of

view An exchange of 10,000 subscribers may

accommodate the SN in a single rack

Two kinds of connections: Switched & Semi-permanent

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ACCESS

This includes:

Line / Trunk Group (LTG) Digital Line Unit (DLU)

Digital Announcement System (DAS

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ACCESSLINE/TRUNK GROUP (LTG)

The line/trunk group (LTG) forms the interface between thedigital environment of the node and the digital switchingnetwork (SN). The LTGs perform non-central controlfunctions and thus relieve the coordination processor (CP)

of routine work.

Several LTG types are available for optimal implementationof the various line types and signaling methods. The twomain types of LTGs (differing in their functionality) used are:

LTG-B

LTG-C

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LTG-B

The LTGB is used for connecting:

Up to four digital transmission routes (PDCs) for

DLUs at transmission rates of 2048 kbit/s Up to four primary rate accesses (PAs) for medium-

sized and large ISDN PABXs (ISDN subscribers

with PA) at a transmission rate of 2048 kbit/s

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Line Trunk Group type-CThe main components of the LTG-C are the same

as that of an LTG-B just that there is differentsoftware downloaded into this LTG type.

This software is capable of handling different kindsof signaling over the trunks.

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Important functions of the LTG-C

1. Receiving and evaluating signals from the trunk

2. Transmitting signals

3. Transmitting messages to the CP and receiving commandsfrom the CP

4. Transmitting audible tones

5. Sending and receiving reports to/from the groupprocessors (GP) of other LTG

6. Sending & receiving orders to/from the CCNC

7. Adapting line conditions to the 8-Mbit/s standard interfaceto the redundant SN

8. Through-connecting messages and user information

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ACCESSDIGITAL LINE UNIT

A digital line unit (DLU) can be used toconnect subscriber lines and PBX access

lines.

The DLU can be operated either locally, or

remotely in the network node.

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Ringing and Metering Voltage Distribution

Each ringing generator and metering voltage

generator (RGMG) has access to a distributionsystem for ringing and metering voltage (ringingand metering bus).

RGMG supplies all mounting locations for analogsubscriber line modules SLMA via ringing/meteringbus.

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Subscriber Line Modules (SLMs)

The subscriber line modules (SLMs) formthe interface to the subscriber.

These are either analog or digital (ISDN).With analog modules these are of two typesnamely non-commercial and commercial.

The commercial-type modules can supplymetering pulses to the subscriber as atstandard 12KHz or 16KHz frequency.

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SIGNALING

The EWSD digital electronic switchingsystem can control connections to and fromother network nodes using all the common

signaling systems.

The signaling functions in an EWSD network-

node are handled by the "common channelsignaling network control (CCNC)".

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SIGNALING

One system that is particularly suitable forstored-program-controlled digital nodes issignaling system no. 7.

This transports signaling informationseparately from the user information (voice,

data) on common-channel signaling links.

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SIGNALING

Advantages

Higher speed signaling

Very reliable signal transmission Flexibility to adapt to future requirements

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SIGNALING

Suitable transmission Medium

Copper Wires

Optical FibersDigital Radio Links

Satellite links

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SIGNALING

Two Kinds of Nodes existing within a No.7signaling network:

Signaling Point (SP)

Signaling Transfer Point (STP)

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THE END

ewsd intro

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