ewsd intro
TRANSCRIPT
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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
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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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ACCESSLINE/TRUNK GROUP (LTG)
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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ACCESSLINE/TRUNK GROUP (LTG)
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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ACCESSLINE/TRUNK GROUP (LTG)
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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ACCESSDIGITAL LINE UNIT
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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ACCESSDIGITAL LINE UNIT
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