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EWSDEWSD “ELECTRONISCHE WHELER SYSTEME “ELECTRONISCHE WHELER SYSTEME DIGITALE”DIGITALE”
EWSD INTRODUCTION
EWSD is the abbreviated form of German equivalent of Electronic Switching System Digital (Electronische Wheler Systeme Digitale).
EWSD Digital switching system has been designed and manufactured by M/s Siemens, Germany.
SYSTEM FEATURES
EWSD system can withstand a BHCA of 4 million with CP-113C in case of EWSD Powermode (two million in case of EWSD Classic).
It can work as local cum transit exchange and supports CCS No.7, ISDN and IN and V5.X features.
SYSTEM ARCHITECTURE
Digital line unit (DLU)
Line/Trunk Group (LTG)
Switching Network (SN)
Coordination Processor (CP)
Common Channel Signalling Network Control (CCNC) Unit or Signalling System Network Control (SSNC)
EWSD
CCNC
OMT PRINTER
MDDMTD
MB
CCGCCGSYP CP
DLU LTG(B)
LTG(C)
SNSN
SUBSCRIBERSSUBSCRIBERSSUBSCRIBERSSUBSCRIBERS
TRUNKSTRUNKS
EWSD ARCHITECTUREEWSD ARCHITECTURE
.
DLU
DLUCC
LTG
GP
LTG
GP
Common channel signalling/ Signalling System Network Control
CCNC/SSNC
Access
Coordination
CPSYPSYPC
MBMBC
CCG
EM
OMT SGC
Switching Network
Distributed controls in EWSD
.
DLU(DIGITAL LINE UNIT)
It is a functional unit on which subscriber lines are terminated.
DLUs are connected to EWSD sub-systems via a uniform interface standardized by CCITT i.e. PDC.
One DLU is connected to two different LTGs for the reasons of security via two 4 Mbps links.
Total 124 channels are available between a DLU out of which the two LTGs signalling information is carried in TS16 of PDC0 and PDC2.
PDC3 without ccs
PDC2 with ccs
PDC1 without ccs
PDC0 with ccs
Subscriber lines and PBX lines for small and medium-sized PBXs
Remote application
Local application
4Mbps
SNLTG
LTG
CP
4 MbpsDLU
DLU
Subscriber lines and PBX lines for small and medium-sized PBXs
CCITT standard interface G.703
Remote application :
in same directory number area,
in another directory number area,
as extension to conventional exchange.
Applications and connection of Digital Line Unit
.
One DLU can carry traffic of 100 Erlangs.
For emergency service DLU-controller (DLUC) always contain up-to-date subscribers data.
Stand Alone Service Controller card (SASCE) is provided in each R-DLU for switching calls in emergency cases .
All DLUs are provided with a Test Unit (TU) for performing tests and measurements on SLCAs(subscriber line ckt. Analog), subscribers lines and telephones.
MAIN COMPONENTS OF DLU SLMAs and / or SLMDs
Two Digital Interface Units for DLU (DIUD) for connections of the PDCs.
Two DLU Controls (DLUC)
Two 4 Mbps networks for the transmission of user information between SLMs and the DIUDs.
Two control network for the transmission of control information between SLMs and DLUCs.
Test Unit (TU), External Alarm module (ALEX) Alarm modules.
.
DLU
Test line
DIUD0
DLUC1
DIUD1
DLUC0
PDC1
PDC0
PDC2
PDC3
to
two
LTGs
SLMA
SLMD
Test
4096 kbps network 0
4096 kbps network 1
Control network 0
Control network 1
TU
Analog
and ISDN
Subscriber
lines, PBX
lines
Main Components of a DLU
.
LTG(LINE/TRUNK GROUPS)
The line/trunk groups (LTG) forms the interface between the digital environment of an EWSD exchange and the switching network (SN).
Maximum traffic handling capacity per LTG is 100 Erlang.
PRIMARY FUNCTIONS OF LTG
Call processing functions – receiving and analyzing line and register signals.
Safeguarding functions – detecting errors in the LTG and on transmission paths within LTG.
Operation and maintenance functions –acquiring traffic data, carrying out quality-to-service measurements.
FUNCTIONAL UNITS OF THE LINE/TRUNK GROUPS
Line / Trunk Unit (LTU) :-
Digital Interface unit ( DIU30 ) for connection of 2 Mbps digital trunks and either DLU or PA.
Code Receivers (CR) are Multi-frequency code receivers for trunks or DTMF subscribers.
Conference Unit, module B or module C (COUB or COUC) for conference calls. This is installed in special function LTGMs or LTGNs.
Automatic Test Equipment for Trunks (ATE:N) checks trunks and Tone Generators (TOG) during routine tests. This is installed in special function LTGMs or LTGNs.
.(8Mbps)
Address signals
SIHO
SIHI
SPHO
SPHI
LTU
DIU30
LTU
COUB
LTU
CR
LTU
ATE:T
CR TOG CTC
SU
SN0
SN1
to/from SN (8Mbps)
GS LIU
or
or
or
GP (PU, MU, SMX and GCG) SILC
Internal Structure of LTG
DIU:LDIB
COUC
PHMA
OCANEQ
.
SIGNALLING UNIT (SU) :-
Tone Generator (TOG) for audible tones.
Code Receivers (CR) for MFC signalling and push-button dialling.
Receiver Module for Continuity Check (RM:CTC), etc.
Group Switch (GS) :- which functions as non-blocking time stage switch
(512 TS) controlled by the GP.
Link Interface Unit (LIU) :- connects LTG to SN via two parallel 8 Mbps SDCs.
GROUP PROCESSOR (GP) :-
controls the functional units of the LTG. The received signals from LTU, SU, GS and LIU are processed with the help of GP software.
SWITCHING NETWORKS
Different peripheral units of EWSD, i.e., LTGs, CCNC, MB are connected to the Switching Network (SN) .
Through 8192 kbps highways called SDCs (Secondary Digital Carriers), which have 128 channels each.
It consists of several duplicated Time Stage Groups (TSG) and Space Stage Groups (SSG) housed in separate racks.
Connection paths through the TSGs and SSGs are switched by the SGC.
Each TSG can accommodate 63 SDCs from LTGs and one SDC to MB.
.
LTG 1
LTG n
CCNC
CP
SPACE STAGE GROUP
TIME STAGE GROUP
SGC
SGC
Switching Network
SDC:LTG
SDC:LTG
SDC:CCNC
SDC:TSG
SDC:SGC
SDC:SGC
SN
MB
SDC:SSG
SDC:SSG
.
COORDINATION PROCESSOR
Storage and administration of all programs, exchange and sub scriber data.
Processing of received information for routing, path selection, zoning, charges.
Communication with operation and maintenance centres.
Supervision of all subsystems, receipt of error messages, alarm treatment, error messages.
Handling of the man-machine interface.
BASIC FUNCTIONAL UNITS OF CP 113C
o Base Processor (BAP) – for operation & maintenance and call processing.
Common Memory (CMY) – 64 to 1024 MB in 4 memory banks consisting of 4
Mb DRAM chips.
Input / Output Controller (IOC) – 2 to 4 IOCs coordinate and supervise accessing of
CMY by IOPs.
.
ATM Bridge Processor (AMP) –
If a SSNC (EWSD powermode) is connected, the AMP is used . It represents the interface between the ATM equipment in the SSNC and the CP.
Input/output processors (IOP) –
Various types of IOPs are used to connect the CP113C to the other subsystems and functional units of the exchange as well as to the external mass storage devices .
.Maximum configuration of CP113C
CAP0 IOC1IOC0BAPSBAPMCAP5
IOP
IOP IOP
IOP
CMY1
CMY0
IOC3IOC2
IOP IOP
IOP IOPBasic configuration of CP 113C,
11
.
.
0
11
.
.
0
B:IOC B:IOC
AMP0 AMP1
Hardware Structure of CP 113 C
.
COMMON CHANNEL SIGNALLING NETWORK CONTROL (CCNC)
It consists of :-
Up to 32 signalling link terminal (SILT) groups, each with 8 signalling links and
One duplicated common channel signaling network processor (CCNP).
FUNCTIONS OF CCNC :-
In the originating or desti nation exchange in associated signalling, it operates as signalling end point (SEP) .
In transit exchange in quasi-associated signalling, it operates as a signalling transfer point (STP).
.
CCS via digital data links
CCS via analog data links
0 310 31
0 70 7
SILT group 31SILT group 0
CCNP 0 CCNP 1
CP bus system
Common Channel Signalling Network Control
MultiplexerModem
.
.
Trunks and SS7 Links
LTG
LTG
SNB
CCNC
MB B
IOP:MB IOP:MB
CP
EWSD Classic Configuration
PCM30
8 Mb/s
4 Mb/s OMT/OMT/CT
.
LTG
LTG
SNB
SSNC
MB D
AMPC IOP:MB
CP
EWSD Powermode Configuration
Trunks and SS7 Links
PCM30/24
270 Mb/s
207 Mb/s
High Speed
SS7 Links
NetM
SIGNALING SYSTEM NETWORK CONTROL (SSNC)
a) ATM Switching Network ASN (2 module frames for ASN 0 and 1)
Switches the communication- streams of the individual SSNC functional units with MB-D and CP.
Switches the communication-streams between the individual SSNC functional units.
.
b) SSNC basic frames SCB
Line Interface Card (LIC):
The duplicated Line Interface Card LIC forms the physical interface between the SSNC units and the SS7 network.
Main Processor MP:
MP: OAM :MP for Operation , Administration and Maintenance.
MP:SLT :MP for Signalling Link Termination. MP:SM :MP for Signalling Manager. MP:STATS :MP for statistics.
.
ATM Multiplexer Type-E (AMXE):
Provides 32 x 207 Mbps ATM interfaces to connect the internal SSNC units LIC and MP and the optical cables to the AMP of the CP and MBDA of the MB.
c) Extension frame SCE (maximum 7 for 1500 signalling channels)
The SCE contains a duplicated AMXE and serves to include other MPs and LICs .
.
Output LTG
ISUP LTG
Inward LTG
AMP MB- D (MBDA)
CP
SNSignaling link
Affecting speech channel
SSNC
OAM
Level 2 & 3(MTP)
Net M
31 SS7- Links
with 64 Kbit/s
or
1 HS- Link
with 2 Mb/S
Direct connected E1 exclusively used for
SS7 links
SSNC Interfaces
.
.
THANKS