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Fathur AB

Anin A

Afif A

Hari A

Gary A

Dhika AB

April AB

Mulya AB

Rizka B

Dion AB

Siska AB

Mirel AB

Hani AB

Airita AB

Yusuf AB

Pilsung AB

Taegyun A


Stored Program Control

Course Number : TTH2A3

CLO : 3

Week : 8


Media Gateway on NGN

• Media Gateway (MG)

– On Transport plane that connects different type of network – Trunk Gateway, connects packet-based network with trunk network from PSTN

or ISDN – Access Gateway, provides services to CPE – Residential Gateway, connects

packet-based network with analog network

• Signaling Gateway (SG)

– Transforming signaling format, ex. SIP SS7

• Media Gateway Controller (MGC)

– Control Media Gateway and Signaling Gateway

– aka. Soft Switch (call setup for multimedia communication, detect and manage events, and manage media gateway based on configuration)

– Use MGCP (MGC Protocol) from ITU-T or Megaco from IETF


Layers in NGN

4


Crossbar Switch

• Electro-mechanical switch by using relay contact

• Numbers are stored in register to establish a call by activating several relay. This activation is done by marker

• Marker will become SPC (Stored Program Control)


Unit Interface for Digital SPC


What is SPC?

SPC (Stored program control) is:

• a telecommunications technology used for telephone exchanges

• controlled by a computer program stored in the memory of the switching system

• SPC was the enabling technology of electronic switching systems (ESS) developed in the Bell System in the 1950s.

source: Wikipedia


Inside the Digital Local Exchange

MD

F M

DF

Subscriber Concentrator Unit Subscriber Concentrator Unit Group Switch Unit Group Switch Unit

subscriber line termination unit

subscriber line termination unit

MU

X

MU

X

digital line termination unit (DLTU)

digital line termination unit (DLTU)

subscriber concentrator switch block

subscriber concentrator switch block

exchange control system exchange control system

analog trunk termination unit

analog trunk termination unit

DD

F D

DF

group switch block

group switch block

CAS CAS

CCS CCS

DLTU DLTU

DLTU DLTU

DLTU DLTU

DLTU DLTU

analog trunk

digital trunk

switch block control





History SPC

• Early exchanges (Strowger and crossbar switches) used analog components (electromechanical switching) without software control

• Invented by Bell Labs scientist Erna Schneider Hoover in 1954

• SPC was introduced in electronic switching systems in the 1960s

• 101ESS PBX was a transitional switching system in the Bell System

• Western Electric 1ESS switch and the AXE telephone exchange by Ericsson were large-scale systems in the public switched telephone network

• SPC enabled sophisticated calling features

• The addition of time-division multiplexing (TDM) decreased subsystem sizes and dramatically increased the capacity of the telephone network

• By the 1980s, SPC technology dominated the telecommunications industry.

source: Wikipedia


Exchange Control System

• Consists of CPU and Memory, to control relay switch

• CPU could be:

– Distributed Control • Vertical Decomposition

• Horizontal Decomposition

– Centralized Control • Standby Mode

• Synchronous Duplex Mode

• Load Sharing Mode


CPU Configuration

• Distributed Control, more available and more reliable

– Vertical Decomposition, 1 CPU for 1 block of exchange

– Horizontal Decomposition, 1 CPU performs 1 function

• Centralized Control

– Standby Mode, 1 CPU on + 1 CPU standby

– Synchronous Duplex Mode, 2 CPU on, provide 2 results to compared

– Load Sharing Mode, all CPU on, load is shared in random


Trunk and Subscriber Line

• Trunk: analog or digital

• Subscriber: analog (PSTN, PBX) or digital (ISDN BRA, PBX PRA)

• Terminating unit should considers: – Varying distance for each subscriber

– Signaling message translation

– Some subscriber still needs ringing current and power feeding

– Features for maintenance and testing


Subscriber Line Termination Unit

Analog SLTU should provides functionalities:

• Battery feeding (power supply, ex. to CPE) -48VDC

• Over voltage protection (ex. from lightning)

• Ringing current (to bell customer)

• Supervision (to detect CPE condition)

• Coding (encoding and decoding between analog and digital)

• Hybrid transformer (conversion from 2-wire to 4-wire)

• Channel testing


Subscriber Line Termination Unit

Digital SLTU should provides functionalities:

• Transfer non-voice data

• Use 64 kbps for data transmission

• Use 16 kbps for signaling (CCS)

• Consists of NTU (Network Termination Unit) and TA (Terminal Adapter)

• Supervision is done at TA


Single Processor vs. Dual Processor

• Availability


Single Processor vs. Dual Processor


See you on next class

soft switch - wordpress.com · pdf file history spc • early exchanges (strowger and...

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