Fetex - digital switching system

Fetex

The FETEX 150 digital switching system has the latest design providing

easy operation and maintenance, advanced capabilities, and highly reliable

operation. The system has been designed to serve as the intelligent node for

ISDN and Intelligent network (IN). This system meets the demands of more

advanced and diversified communication networking by the use of advanced

switches and PCM transmission technologies.

The transmission environment influences introduction of digital

switching system. As digitization of transmission facilities increases, the more

economical the introduction of digital switching system becomes.

Introduction of remote line concentrator and remote line multiplexers

greatly reduces subscriber loop cable length and concentrates several

thousand-subscriber lines on to a few PCM lines. This enables economical

expansion in urban and rural areas, and allows easy introduction of new

services to a wide area.

Design concept

During research and development of the FETEX-150 system, the

following basic design concepts are followed:

One-Machine concept

The system can serve for any of the following applications:

INTS: International Toll Switch

TS: Toll Switch

MS: Tandem Switch

LS: Local Switch

STP: Signal Transfer Point

Technology Independencen

The systems modularity and software functional blocks make it easy to

continuously incorporate new technology, innovations and additional new user

capabilities.

Standardization

The FETEX-150 system follows ITU-T/Bellcore/T1/ETSI standards,

allowing integration of the FETEX-150 system into a multi-vendor network.

The modularity of equipment and software function blocks and well-

defined interfaces between the modules are essential to meet the design

concepts. In the FETEX-150 system, all the function modules are designed on

an open-ended feature basis to permit easy introduction of new capabilities, to

be economically configured in any application and any switch size over the

entire switch range.

The basic services of the FETEX-150 system are as follows:

ISDN-oriented services

Multimedia/ multi-channel services

I-Series Signaling Base Advances Telephone Services

POTS

Conventional Signaling Base Telephone Services

Data Services

Conventional Data Switching Services

(Telex/Packet/Circuit Switched Data)

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Outstanding features

Fetex

The system provides a number of features, some of which are described

in the following paragraphs.

Wide range of applications

The modular construction of the FETEX-150 in both hardware and

software gives it maximum flexibility for a variety of applications. The multi-

processor system has 1,800,000 BHCA capacity and the uniprocessor system

has 250,00 BHCA capacity. In addition, the FETEX-150 system has the

following capacities:

240,000 lines or 60,000 trunks

24,000 Erlangs

Processor organization

The system can be configured with a single processor or with multi

processor, making it cost competitive for small to large-capacity applications.

In the uniprocessor configuration, functions of the Call Processor are

incorporated into the Main Processor. The hardware and software are designed

to make it possible to change from uniprocessor to multiprocessor system.

This conversion can be done on-line with minimum effect on call processing.

Installation

The FETEX-150 system is designed either for a building or container

housing. The system is essentially the same in either installation. Because of

the following features, installation is easy, simple, and quick:

Space-saving with high technology components.

Rapid and convenient wiring.

Software is thoroughly tested during development, and hardware is

completely tested in the factory.

The Small-version, container type FETEX-150 system can provide 2000

lines with a basic container, and up to 10,000 lines with a basic container and

three expansion containers.

Modular Structure

All functional modules of the FETEX-150 system are connected through

a unified, universal interface. The integrity of each hardware and software

module is strictly maintained. System organization also allows smooth

upgrading and uninterrupted service as new devices are added

Advanced software

Advanced software technology and high reliability characterize the

system software including the following development features:

Applications are programmed using a high-level language.

Man-machine language is based on ITU-T and Bellcore standards.

Functional specification and description language is used to

document call-processing software.

Simple network topologyl

The FETEX-150 network is configured as a TST switch. The internal

speed of the network module is 8Mbps in an 8-bit parallel configuration,

providing a high-speed, large-capacity switch module. Each switch module has

1,024 time slots and 380 Erlangs of through-traffic capacity with virtually no

blocking. Additional switch modules can be installed by interconnecting them

with existing highways between modules during expansion.

Easy maintenancen

The maintenance and operation provides system supervision and control,

man-machine interface, and automatic testing and diagnostics. Access

provided through intelligent workstations allows maintenance personnel to

operate and maintain the system without the assistance of specialized

personnel.

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New features

Fetex

The FETEX-150 system employs a number of features like Signaling

System No. 7 and ISDN.

System applications

The FETEX-150 system can be applied to any switching node in the

public switching network. Summaries of system specifications and applications

are as provided:

Item

Processor architecture

Application

Capacity

Terminations

Traffic

Attempts

Speech path network

Main Memory (MM)

File Memory (FM)

Floor Loading

System configuration

Specification

Distributed multiprocessor hierarchy

INTS: International Toll Switch

TS : Toll Switch

MS : Tandem Switch

LS : Local Switch

STP : Signal Transfer Point

240,000 lines or 60,000 trunks

24,000 Erlangs

1,800,000 BHCA

TST

1,024 Time Slots per module

380 Erlangs per Module

8 Megawords per Central Controller

32-bit word + Error Check and

Correct / parity.

4 Mw per FM

4 Mw x 4 per Central Controller

32-bit word + Error Check and

Correct.

300 kg/m² (single cabinet)

The system is composed of modular hardware and software systems.

Software is organized hierarchically into system, subsystem, block,

component, and unit levels. Units are compatible and linkable entities.

The FETEX-150 system has an effective division of functions between

hardware and software, providing great flexibility for future function additions.

All functional modules, whether hardware or software provide unified internal

interfaces.

The hardware system comprises the following three functional subsystems:

The speech Path Subsystem (SPS) forms the actual switching fabric for a

cell under control of the Central Processing Subsystem (CPS).

The CPS controls all switching system functions and is interconnected with

the SPS and the MOS

The MOS provides man-machine communication, system supervision, and

testing functions for maintenance and operation of the system.

Multiplexi

The FETEX-150 system employs a TST Digital Switch Module (DSM).

The input to the DSM is 8 links with an 8 Mbps serial bit stream. This is

multiplexed in the DSM at 8 Mbps on an 8-bit parallel basis, providing 1,024

TS.

The maximum system configuration is 64 DSMs, which is 65536 TS.

Within the 1024 TSs, 960 are used for call connections and the remaining 64

for internal processing.

Processor configuration

The FETEX-150 system employs a hierarchical processor arrangement.

The highest level is the duplicated Main Processor (MPR) which controls overall

system operation. A maximum of 8 duplicated Call Processors (CPR) can be

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Fetex

equipped under one duplicated MPR. At the lowest level, duplicated Line

Processors (LP) control the line concentrator stage.

Inter-processor communications of various types that are used are:

MPR and CPR communication is performed through a unified

interface.

CPR and LPR communication is via the SGC and CSE using duplicated

SS7 channels.

CPR to CPR communication is performed via MPR.

Communication between LPR and CPR

The signaling controller on the LPR side and Common channel signaling

equipment on the CPR side performs communication between the LPR and

CPR. This communication is passed through a pair of 64 KBPS signaling

channels on the 8 Mbps highway for the LC and on the PCM lines for RLC,

acting on a load-sharing basis.

SS7 is employed as signaling protocol for the following reasons:

Flexibility for future modification

Compatibility with the D-channel protocol of ISDN lines.

Layered and message based signaling.

Line concentrator (LC)

The FETEX-150 system has 2 types of LCs. Type A is economical for

small systems. The type B has more capacity and features than A.

Subscriber interfaces

A point of LC-As can accommodate analog subscriber lines. The LC-B

can accommodate both basic rate ISDN subscriber lines (2B+D) and primary

rate access and digital subscriber loop carrier interface in addition to analog

subscriber lines.

Traffic usage and call attempt capacityi

The LC-A has one internal highway 8 Mbps connected to the DSM with

120 channels available for user channels. The LC-A uses an 8-bit processor for

call handling.

The LC-B has up to 8 internal highways connected DSM with a

maximum of 960 channels available for user channels. Intra-LC calls are

connected within the LC reducing the number of channels to the DSM. This is

an especially important benefit for the Remote Line Concentrator (RLC)

application of the LC-B because it reduces a number of channels necessary

between the RLC and the host switch. The LC-B uses a 32-bit processor for

call handling.

Remote concentrator (RLC)

The FETEX-150 system has 2 types of RLCs for cost-effective

applications in a local plant. RLC-A is economical even for a small number of

lines. RLC-b has more capacity and features.

RLC-A

The RLC-A depends on a host switch for call processing functions as well

as maintenance and administration. The arrangement provides a low cost

system.

Call processing features

The following are the major call processing features:

Ordinary subscriber lines long lines and coin lines such a variety of line

types but analog are supported.

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Fetex

Intra-RLC connections can be provided at RLC-A by looping back the link to

the host, which reduces the links to the host.

The RLC-A can operate in a stand-alone mode with stand-alone equipment.

When the links to the host fail, the RLC-A and the stand-alone equipment

provide basic call processing. Stand-alone equipment can cover up to 5

RLC-As.

Maintenance and administration featuresr

The RLC-A depends on the host for the following maintenance and

administration processing functions, as well as the man-machine interface

device.

Charge recording: performed at the host and also stored at the host

storage device.

Man-machine interface: command input and message outputs related to

the RLC-A are performed through the host man-machine interface devices.

Stand-alone features

When RLC-host links fail, the RLC-A automatically moves to a stand-alone

mode.

Charging recording: During stand-alone operation, charging data is

recorded in extension memory cards.

Emergency access trunks: access is provided to specified destinations or

other central offices using outgoing trunks.

Stand-alone announcement: the system can notify subscribers of the

stand-alone operation mode at call origination.

RLC-B

RLC-B depends on a host switch for call processing functions as well as

maintenance and administration. This arrangement provides a low cost

system.

Call processing features

The following are the major call processing features:

Small call processing features which are provided for the LC-B are also

prepared for the RLC-B

The RLC-B can operate intra RLC connections in a stand-alone mode.

Stand-alone features

During stand-alone operation, charge recording is provided using

optional FM for intra-RLC calls.

Connecting a portable workstation to the RLC-B provides limited

maintenance features.

The system can notify subscribers of the stand-alone operation mode

at call origination.

Reliability

The FETEX-150 system is very reliable because of the following design

features:

Modular design

Duplicated architecture

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Fetex

Quality control performed throughout manufacturing of all components and

equipment.

Software system reliability

Hierarchical memory structuret

Memory is organized into the following levels:

1)Main memory (MM) 2) File memory (FM) 3) Magnetic tape (MT)

Restart process

Four phases of system restart, each selected according to the fault

conditions, minimize the effect of system restart on call processing.

Post analysis dump

On the occurrence of a software fault, the contents of temporary data

areas in MM are transferred to FM.

Audit

The software system provides a built-in audit facility to detect software

faults, such as program maze or abnormalities in data. The audit facility

enables early detection of software faults.

Fault detection methodt

For maintenance of stability of continuous call processing services, the

system employs a rotation method for isolating faults in which doubtful

equipment is replaced with a standby one.

External supervision facility

System operation is continuously checked through the External

Supervisory Equipment. If any abnormality is detected the emergency action

circuit activates a system restart.

Hardware system reliability

The FETEX-150 system provides full redundancy throughout the system

except at the terminal end. This is used to safeguard operation in areas in

which a failure can influence a large number of calls.

Maintenance and operation

The maintenance and operation features of the FETEX-150 system are:

High reliability

High reliability supported by an automatic reconfiguration system, which

uses the built in redundancy.

Easy maintenancen

The maintenance and operation subsystem provides automatic testing

and diagnosis.

Software featuresr

The FETEX-150 system software is composed of real time and

multiprocessing program modules.

Software based on ITU-T recommendations

Specification description language (SDL)

Man-machine language (MML)

High level language (HLL)

Flexible software

Generic standard program

System software is composed of the following:

Operating system subsystems common to all FETEX series switching systems

Application subsystem controls specific switching functions.

Office data specifies the conditions of a particular office.

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Subscriber data specifies conditions of each subscriber such as class of

service, numbering, equipment location, features, etc.

Modular structure

Fetex

A program module is provided for each switching function. Each module

is interconnected by means of a data table. This structure allows each

program to be independent, resulting in program reliability and flexibility.

File updating

Office files are loaded by command for updating existing files. Files of a

working office can be updated with only a slight effect on the cal processing.

1. TYPES OF SUBSCRIBER LINE

1.1

1.2

2.

TYPES OF TELEPHONE

Rotary telephone (10PPS or 20PPS)

Push button telephone

ISDN terminal

SUBSCRIBERS LINE CLASS

Individual, PBX, and party lines

Unit fee coin telephone

Multi-fee coin telephone

ISDN basic rates access line

ISDN primary rate access line (B/H channel interference)

SUBSCRIBER SERVICES

2.1 TYPE OF CALL

Intra-office calls

Local call

Subscriber toll dialing (STD) call

International direct dialing (IDD) call

Toll call via operator

International call via operator

Special service call

2.2 BASIC SUBSCRIBER SERVICES

a) PBX facility

The extension in a PBX group can be accompanied with non-consecutive

circuit locations. The following additional facilities are provided.

Night line service of PBX

Number of PBX terminating lines is reduced by a request signal from the

PBX. The lines to be blocked are given by the command

PBX in dialing

This service allows a calling party to be directly connected to a desired PBX

extension by dialing the directory number of the extension. Digit

translation for identification of DID (direct in dialing) PBX is 5 or less.

b) Coin telephone facility

c) Malicious call trace facility

Malicious call tracing by printing out the calling subscribers number, called

subscribers number, and other relevant information when the called

subscribers flashes his hook switch. An audible alarm is used at the same

time. The call is held under the control of called party.

d)

Changed number interception (CNI)

Calls to subscribers whose directory number has changed are rerouted to

operator or an announcement machine.

e) Denied service

Denied service (originating)

Call origination is denied by sending busy tone to a subscriber who has this

service class when he picks up the handset.

Denied service (terminating)

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Fetex

Call termination is denied by sending a special tone to subscriber

who dials the number in this service class.

f) Semi-permanent connection

A 64KBps connection can be setup between 2 network inlets

designated by a command.

g) Tone and talkie service

h) Charging free connection

i) Trunk offering (TKO)

This service is provided to permit operators to access a busy line

2.3 SUPPLEMENTARY SUBSCRIBER SERVICE

a) Abbreviated dialing

Subscriber with push button telephones make calls, including IDD

by dialing only a 3 digit dialing code

b) Call transfer

c) Call waiting

d) 3 way calling

Allows conversation among 3 subscribers

e) Telephone rest service

Calls to this subscriber will be routed to an announcement

system. The service can be registered or cancelled by dialing

special codes.

f) Absentee service

All calls to this subscriber are terminated to a special

announcement

g) Automatic wake up service

h) Hot line

Can connect to pre-determined number by just picking up the

hand set.

i) STD call and/or IDD call barring

3.

SIGNALING

The FETEX-150 system can handle the following signaling systems :

Subscriber line signaling

Dial Pulse

Dual Tone Multifrequency

ISDN D-channel protocol

Junction line signaling

DC loop signaling

E & M signaling

Digital line signaling

Register signaling

DP signaling

RVP signaling

MF signaling

MFC signaling

Common channel signaling

ITU-T signaling system no.7 (SS7)

4.

SWITCHING FEATURES

4.1 NUMBERING PLAN

Directory number independent of location

Directory numbers can be assigned independently of

equipment location

Non-consecutive numbering on PBX

No restrictions on using non-consecutive directory numbers

to make a PBX group

Various numbering plans can be adapted for any custom as

numbering processing is controlled by software.

4.2 TRANSLATION AND ROUTING

Translation

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Digit translation of up to 8 digits within a maximum of 24

stored digits, including prefix and/or special codes.

Route size

Outgoing route: Max 1,024 including DID, PBX routes and

talkie

Incoming route: Max 1,024

Alternative routing within 8 routes

Digit deletion of 0 to 7 or all digits and digit insertion and

substitution of up to 5 digits within 63 patterns.

Trunks are fully accessible without grading

Random selection of trunk in a route

4.3 RELEASE CONTROL

Normal calls are held under the control of calling party.

Emergency calls such as Fire, Police are held under the

control of called party.

Connection is forcibly released if the called party does not

respond within a pre-determined time.

4.4 TIME SUPERVISION

Permanent signal partial dialing (PSPD) timing

PSPD timing is applied for detection of permanent signal

and partial dialing.

Inter digit (ID) timing

ID timing is applied for detection of last digit when

numbers of different digits are sent on the same route.

Reanswer time supervision

Time supervision is applied from the receipt of clear-back

signal to the receipt of clear forward signal

4.5 OTHERS

Automatic number identification (ANI)

Identification and sending of calling subscribers directory

number in response to a request signal from the

succeeding exchange.

5.

5.1

5.2

5.3

6.

CHARGING FEATURES

Charging system

Flat rate

Message rate

Measured rate

Charging by call duration and charging rate.

CHARGING SYSTEM

Periodic pulse metering (Bulk accounting)

Automated message accounting (LAMA/CAMA)

AUTOMATIC CHARGING INFORMATION

After the conversation, the duration of call and/or charge are

reported to the calling subscriber by the operator, voice response

equipment or output to the printer.

MAINTENANCE AND OPERATION FEATURES

6.1 SYSTEM STATUS MANAGEMENT

System status identification

Alarm facility

Route alarm indication

Equipment status and alarms are indicated on the TCNS (test console)

by function key operation and detailed information is displayed when

commanded. On detection of an abnormal state the visual and audio alarms

are blown. Routes are also displayed on TCNS when commanded.

6.2 FAULT PRCESSING AND DIAGNOSIS

Automatic fault processing

Auto detection and isolation of faulty equipment is done

and system is reconfigured automatically.

Diagnosis

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Diagnosis is carried on an on-line basis and the location of

faulty equipment is displayed on the SCWS/VDU.

6.3 TRAFFIC CONTROL

Automatic load control

In case of a system overload, calls originating from

subscribers and incoming calls are gradually restricted

according to priority of subscriber and incoming trunks.

Routing control

For outgoing congestion, outgoing calls are restricted by

command activation.

Dynamic

The system periodically decides a maximum number of

calls to be handled by the system. Even under overload

condition, the system accepts calls as much as possible for

the processor.

6.4 TRAFFIC MEASUREMENT

Traffic data such as junction traffic, number of calls, and occupancy

of control equipment, is collected. The data can be displayed on the

VDU, SCWS, MT or LP. The following 3 measurements are provided.

a) Routine measurement:

Carried out on a routine basis

b) Special measurement: Carried out to measure more detailed

characteristics of a specific equipment or item such as

incoming route than routine measurement only when

activated by command.

c) Fluctuation measurement: This command is activated by

command, to supervise traffic fluctuation.

6.5 OBSERVATION

Subscribers dialing

Designating subscribers through the SCWS/VDU collects

subscriber-dialing behavior.

Charge observation

Detailed charging data including the detailed number,

time answered, time disconnected, and metering

information are collected for each call by designating

subscribers through the SCWS/VDU.

6.6 SUBSCRIBER DATA & OFFICE DATA CHANGE

Subscriber data change (Service order)

Subscriber data such as class of service, directory

number, etc. can be changed using a command input

without disturbing the call processing.

Office data change (Recent change)

Office data such as routing and signaling can be

changed by a command input, without disturbing call

processing.

6.7 CENTRALIZED MAINTENANCE & OPERATION (OPTION)

The CMOC (Centralized Maintenance and Operation) facilities are

provided for effective use of manpower and overall supervision of

network.

SYSTEM DESCRIPTION

Overview

The FETEX-150 system consists of the following major subscriber-

systems

Speech path sub system (SPS)

Central processing sub system (CPS)

Maintenance & Operation subscriber system (MOS)

SPEECH PATH SUBSCRIBER SYSTEM (SPS

The major function of the SPS is to interface analog lines, digital lines,

integrated services Digital Network (ISDN) subscriber lines, analog trunks,

and to provide switching functions.

For line interfaces, a line Concentrator (LC) or a remote Line

Concentrator (RLC) is employed to concentrate customer traffic for

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Fetex

connection to a Digital Switch Module (DSM). Trunks are connected to the

DSM by trunk interface circuits without concentration.

DSM controls switching. Peripheral equipment, e.g., LCs, Analog Trunk

Shelves (ATSH), Digital terminal Shelves (DTSH), and receiver Shelves

(RECSH), are connected to the DSM via optical 8Mbps highways. This is a

common interface used throughout the system and is also used for

peripheral/application modules connected to the LC or RLC, such as

Subscriber Line Circuit Shelves (SLCSH), Digital Subscriber Line Circuit

Shelves (DLSH), and DTSHs. The optical highways are used for the

following reasons:

High data rate capacity

Immunity from Electromagnetic interferences

Reduction in the number of transmission cables

The SPS is connected to the CPS via a duplicate Speech Path (SP) bus.

The Call processor (CPR) of the CPS controls the DSM and the peripheral

modules.

LINE CONCENTRATOR TYPE A (LC-A)

LC-A provides the line interface, front-end, and pre-processing for call

control between subscriber lines and the DSM. LC-A contains following

equipments:

a) Line Processor Shelf (LPRSH)

Line Processor (LPR)

Line Control Memory (LCM)

Sending Signal Memory/Receiving Signal Memory (SSM/RSM)

Scanner/Signal Distributor (SCN/SD)

b) Subscriber Line Circuit Shelf (SLCSH)

Line Concentrator Time Switch (LCTW)

Analog Subscriber Line Circuit (SLC)

LINE CONCENTRATOR TYPE B (LC-B)

LC-B contains following equipments:

a) Central Processor Shelf

Line Processor (LPR)

Signaling Controller (SGC)

b) Line Switch Shelf (LSWSH)

Signal Receiver And Distributor (SRD)

Scanner/Signal Distributor (CSN/SD)

Signaling Interface (SGIF)

Network Interface (NWIF)

The line interface equipment consists of:

a) Subscriber Line Circuit Shelf (SLCSH)

Analog Subscriber Line Circuit (SLC)

b) Digital Subscriber Line Circuit Shelf (DSLCSH)

Digital Subscriber Line Circuit (DLC)

c) Digital Terminal Shelf (DTSH)

Digital Terminal (DT)

Line Processor

The LPR consists of a duplicated 32-bit processor, Main Memory (MM),

and a Channel Controller (CHC). The LPR performs call processing and

maintenance and administration functions in cooperation with the CPR. The

LPR communicates with the subscriber equipment and the CPR via the

SGC.

Signaling Con troller

SGC is a High level Data Link Control Procedure (HLDC) handler. SGC

acts as an interface for communication with the following equipments:

a) DLCSH b) DTSH

c) CPR

Line Switch

The LSW is a one-stage time switch performs concentration and

provides intra-LSW connections. It consists of 6 switching network

modules. Each module consists of 1,024 time slots. Thus, LSW can

accommodate up to 6,144 time slots (1,024x6=6,144).

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Each switching module consists of 8 optical 8Mbps (128 time slots per

highway). Up to 48 highways can be connected to one LSW.

Signal Receiver & Distributort

SRD is hardware to software interface. Under control of LPR it controls

LSW and the SCN/SD signal sending and receiving between line interface

equipment.

Scanner/Signal Distributort

The SCN/SD is a memory for signal receiving and sending between the

line interface equipment and the SRD. The SC/SD communicates with the

following equipment:

a) SLCSH

b)DTSH

Network Interface

NWIF connects LSW to DSMs via duplicated 8Mbps highways. NWIF has

following main functions:

Electrical and Optical signal conversion

NRZ to and from CMI code conversion

Clock extraction from received data

Signal Interface

SGIF connects SGC to LSW. It also converts 64Kbps highways from the

SGC to interface with the LSW and vice versa.

ANALOG SUBSCRIBER LINE CIRCUIT (SLC) and ANALOG SUBSCRIBER LINE

CIRCUIT SHELF (SLSCH)

Subscriber Line Circuit

Each SLC, depending on class of service, is equipped with a per-channel

CODEC and a software selectable hybrid-balancing network.

Subscriber Line Circuit Shelf

The SLCSH is a shelf to accommodate SLC. One SLCH can accommodate

a maximum of 240 circuits.

DIGITAL SUBSCRIBER LINE CIRCUIT (DLC) & DIGITAL SUBSCRIBER LINE

CIRCUIT SHELF (DLCSH)

Digital Subscriber Line Circuit (DLC)

DLC provides basic rate access to ISDN lines (2B+D) and an interface to

DLCC. DLC uses echo cancellation methods (ECM), performs activation/

deactivation control, and multiplexes/De-multiplexes B-Channels and D-

Channels.

Digital Subscriber Line Shelfh (DLSH)

One DLC card accommodates one (2B+D) circuit. Thus, 1 DLCSH can

accommodate up to 56 circuits.

REMOTE LINE CONCENTRATOR (RLC)

The FETEX-150 has 2 types of RLCs viz; Type A and Type B.

REMOTE LINE CONCENTRATOR TYPE A (RLC-A)

RLC-A is LC-A, which is located at a remote location and connected via

PCMs.

RLC-A and LC-A have similar configurations. A single RLC-A can

accommodate up to 4 PCM-30 systems or 5 PCM-24 systems to host.

REMOTE LINE CONCENTRATOR TYPE B (RLC-B)

RLC-B is LC-B, which is located at a remote location and connected via

PCMs.

RLC-B and LC-B have similar configurations. RlC-B can accommodate up to

88 PCM-30 systems or 110 PCM-24 Systems to host.

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DIGITAL SWITCH MODULE (DSM)

Fetex

DSM is a 3 stage (Time-Space-time) switching network, virtually non-

blocking, and duplicated in hot standby mode. Each module can handle up to

380Erlangs of traffic (960 CH) and the total traffic handling capacity of system

is 24,320Erlangs (61,400 CH). It has a 8Mbps (8 bit parallel) interface. Each

network has the following:

Secondary Multiplexers (SMPX)

Primary Time Switch (PTSW)

Space Switch (SSW)

Secondary Time Switch (STSW)

Secondary De-multiplexers (SDMPX)

Control Memory (CM) for the control of PTSW, SSW, and STSW

PCM code Conversion (PCC)

ANALOG TRUNK CIRCUIT (AT) & ANALOG TRUNK SHELF (ATSH)

ANALOG TRUNK CIRCUIT (AT)

AT circuit is an interface between analog trunks and the DSM. Trunk

circuit converts analog signals to digital form, and vice versa. A per channel

CODEC and metallic test access are provided for each AT circuit.

ANALOG TRUNK SHELF (ATSH)

It is used for analog trunks. An optical 8 Mbps highway with 128 time slots

is used between the ATSH and DSM. In addition to the various analog trunk

cards for interoffice trunks, the ATSh accommodates miscellaneous

equipment, such as 3-way calling circuits, interface trunks for the

announcement system, test equipment.

DIGITAL TERMINAL (DT) & DIGITAL TERMINAL SHELF (DTSH)

DIGITAL TERMINAL (DT)

DT is used for PCM line interface interoffice trunks, links for RLCs, RLMs

and ISDN primary rate interface.

DIGITAL TERMINAL SHELF (DTSH)

It consists of Digital Terminal Common (DTC) and Digital Terminals (DT).

DTCs are duplicated and connected to DSM via a pair of duplicated 8Mbps

highways. DTC acts as an interface circuit between DT and DSM.

TONE GENERATOR (TNG) & SIGNAL RECEIVER (REC)

FETEX-150 system employs technology independent tone distribution and

signal receiving techniques. The Tone Generator and Signal Receiver are

mounted on the RECSH. Optical 8Mbps highways are used for links between

DSM and RECSHs. One RECSH can terminate up to 120 channels/128 time

slots.

TONE GENERATOR

TNG is a digital tone generator for DTMF (Dual Tone MultiFrequency) and

MultiFrequency (MF) signals, providing mixed tones. It can accommodate up

to 26 tones other than DTMF & MF tones which are sent to DSM via the

Upward Sub highway (USHW) of the DSM.

SIGNAL RECEIVER

Signal processing of MF signals from associated switches and DTMF signals

from subscribers is carried out in RECSH. The primary MUX/DeMUX are located

in RECSH and provide digital type MF receivers. A single RECSH can process

up to 120 channels/128 time slots. The 120 multiplexed channels of MF signals

in the Downward Sub highway (DSHW) are demultiplexed in the PDMPX of the

RECSH to provide up to 8 receivers (REC).

DIGITAL ANNOUNCEMENT MACHINE (ANM)

63

Fetex

The ANM is installed as an option when announcements to subscribers are

to be supplied. It can handle up to 8 messages with a storage capacity of 253

seconds (variable) per message.

VOICE RESPONSE EQUIPMENT

The voice response equipment, available as an option, is used for services

that indicate charging information, change of directory number to calling

subscribers, etc. the voice response equipment can compose messages for

these services. The specifications of VRE are as follows:

ITEM

Control Method

Loading of Voice data

Segment length

Multi-frequency tones

Total voice messages

Voice channels

Voice memory device

Voice segments per message

SPECIFICATION

Microprogram Control

Loading from floppy disk or

Winchester disk

Max 33 min

Max 60

Max 400

Max 72 channels (PCM-24)

Max 90 Channels (OCM-30)

IC Memory

Max 400

CENTRAL PROCESSING SUBSCRIBER SYSTEM (CPS)

The CPS consists of the Main processor (MPR) and the Call processor

(CPR). MPR performs overall functions including O&M while CPR is

dedicated for call processing and makes use of the LPR in the LC or RLC.

MPR is the highest while the LPR is the lowest in the processor hierarchy.

The configuration of a CPS is shown below.

Communication between CPR and MPR through the Channel-to-Channel

adapter (CCA). For uniprocessor switches, the call processing functionality

is included in the MPR itself. The Common Channel Signaling Equipment

(CSE) is a protocol handler for SS7 level 2.

The CPR and MPR developed for telecommunication purposes consists of

the Central Controller (CC), CHC, MM and FM. Central processing is

performed on a stored program control basis similar to that of general

purpose computer. All CPS units are duplicated to cope the failures.

CENTRAL CONTROLLER (CC)

Specifications of the CC are given in the table below.

SPECIFICATION

ITEM

General Register Micro program control with customer VLSI

processor

Instruction Set 162 instructions

Interruption

Level

Word length

2 levels. CLASS A=25/ CLASS B=12

32 bits + 7 bit error check and correct

(ECC) / 1 parity bit

The following are the functions of the CC:

a)

System control operation: Controls connections among the CC,

CHC and SPS

b)

c)

Arithmetic operation

Interrupt operation: fault interrupts, real time interrupts,

interrupts from the CHC, etc.

d)

Emergency operation: When program processing becomes

impossible because of faults, the emergency circuit establishes a new

system configuration. The operation mode of CC is based on hot-

standby operation.

64

MAIN MEMORY

Fetex

The MM stores the system program and data. It consists of one package

with control part and a memory part. Its capacity is 4Mw (32-bit word)

The MM is duplicated and the operation mode of MM is based on hot-

standby operation. The specifications of MM are as given below.

FILE MEMORY

ITEM

Capacity MEMORY Unit

MAXIMUM

Memory Component

SPECIFICATION

4Mw X 32 bits

words/MM

4Mbit per Chip MOS LSI

It serves as a highly reliable random access file for the storage of

program and data. It consists of a File Memory Controller (FMC) and a File

Memory Unit (FMU) that has a capacity of 4Mw. The CC can connect up to

4FMs.

The FMC and FMU are duplicated and operation of FM is based on hot-

standby operation.

The specifications of FM are tabulated below.

ITEM

Capacity Memory

Unit

Maximum

Control Feature

Data Check

Memory Component

CHANNEL CONTROLLER (CHC)

SPECIFICATION

4Mw X 32 bits words

16 Mw X 32 bits words

Micro program control

Single bit error Detected and

Corrected

Double bit error Detected (ECC)

1 Mbit per Chip MOS LSI

The CHC transfers data between the MM and the FM or input/output

(I/O) equipment on receiving instructions from the CC. It can execute

programs independently of the CHC during CHC data transfer. It is also

duplicated and can be connected with a maximum of 60 I/O devices.

CHANNEL-TOT -CHANNEL ADAPTER (CCA)

When multiprocessor configurations are employed CCA acts as an

interface between CPR and MPR. It is connected to CHC through a common

bus interface, and also connected to the mate CCA through a CCA interface.

CCA transfers information required for call processing between MPR and CPR.

CCA on instruction from CC, autonomously transfers data between CCA and

MPR. CCA is duplicated for each CPR for higher reliability.

COMMON CHANNEL SIGNALING EQUIPMENT (CSE) AND RELATED EQUIPMENT

The FETEX-150 system employs SS7 signaling for communication between

CPR and LPR.

The use of SS7 signaling in FETEX networks has the following features:

Full implementation of CCITT recommendations

Flexibility in application fields not limited to interoffice signaling of

telephone calls

Large capacity

Variety of signaling interfaces

Minimum effect on processor load

The functions of SS7 are divided into 4 levels. In the FETEX-150 system,

these 4 levels are implemented separately as follows:

Level 1:

Level 2:

Level 3:

Level 4:

DSM and DT, or modems for analog links

CSE

CPR software

CPR software

Modems, CSEs, and CSE Interface (CSEI) are required by external SS7

interfacing.

The sys configuration of the FETEX-150 sys is as shown below.

65

COMMON CHANNEL SINALING EQUIPMENT

Fetex

The CSE provides level 2 functions. CSE manipulates various signaling

bit rates (i.e. 64 Kbps, 56Kbps, 48Kbps). One CPR can connect up to 32 CSEs

and one CSE can accommodate up to 8 signaling data links. The specifications

of CSE are tabulated as follows.

ITEM

Call processing Interface

Function

Number of CSEs

Number of signaling data

Processor

Signaling bit rate

SPECIFICATION

Common Bus DMA mode

SS7 level 2

32 CSEs per CPR

256 CSEs per system

8 links per CSE

16-bit processor

PCM: 24/30:64Kbps/56Kbps/48Kbps

COMMON CHANNEL SIGNALING INTERFACE (CSEI)

The CSEI is located between the CSE and the DSM to convert the data

transmission spaced between the data on a time slot of optical 8Mbps highway

to the DSM and the 64 Kbps to or from the CSE.

MAINTENANCE AND OPERATION SUBSYSTEM (MOS)

The MOS executes various maintenance and operation tasks under

control of MPR together with a man-machine interface terminal, storage

deices, alarm supervision equipment, and line/trunk testing equipment.

Following table gives an description of the MOS equipment.

ITEM

Workstation (SCWS/TWS)

Magnetic tape unit

CMOC interface equipment

WORKSTATION (WS)

DESCRIPTION

Command input

Message output

System supervision and control

Test functions

- Line/line circuit test

- Trunk/trunk circuit test

System software backup

Mass data storage for off-line

transfer

Interface to centralized maintenance

and operation center

The WS is an intelligent man-machine language interface terminal which

s composed of

Processor

CRT display

Keyboard and Printer

HDD and FDD

Multi-telephone set (MTS)/Handset

System control WS (SCWS) or Test WS(TWS) may be configured for

various different types of works.

The various functions of the WS are tabulated as follows:

TYPE

SCWS

TWS

VARIATION

I

II

III

I

II

III

*

TRUNK TEST LINE TEST

* System Supervision & Control

66

The following table gives the various equipments associated with

TWS/SCWS and the functions associated with each.

EQUIPMENT FUNCTION

Fetex

Alarm Indication Panel Unit

(ALIPU)

Alarm Control Shelf (ALMSH)

Analog Line & Trunk Test Interface

(ALTI)

Automatic Test Trunk Equipment

(ATTE)

Complaint & Transfer Service Unit

(CATS)

CAT Interface (CATI)

Communication Box (CBOX)

Digital LTE (DLTE)

External Supervisory Equipment

(ESE)

External Supervisory Equipment

for LPR (ESEL)

Junction test Equipment (JTE)

Line SCN/SD equipment (LSCD)

Line Supervisor (LSUP)

Line Test Adapter (LTAP)

Line Test Equipment (LTE)

OCE (Office Communication

Equipment)

System Test Adapter

MAGNETIC TAPE UNIT (MTU)

Trouble notification with buzzer

tone and flashing LED indication

Alarm data processing, including

detection, analysis, transfer to

CMOC and indicators

Protocol conversion to/from

LTE/WS

Trunk test circuit for loop back

establishment

Complaint call receiving & transfer

it to others CATS, TCNS, CBOX

and exiting console

Complaint call receiving from

subscriber. Sending of holding

tone

Complaint call receiving. AC jack

for transmission measurement

LTE function for digital subscriber

lines

Supervisory equipment for CPR

Supervisory equipment for LPR

Automatic junction test equipment

with automatic call generator and

responder

Scan signaling transfer from LP to

LPR

SD signaling transfer from CPR to

LC

Faulty subscriber line supervision

from MDF

Interface facility between

controlled exchange and MTWS

Automatic Line/line testing circuit.

Office communication between

CBOXs and exiting consoles

Interface facility between

controlled exchange and MSCWs

The MTU is used for mass data storage, and for input and output

of programs and data.

SERIAL INTERFACE ADAPTER (SIA)

The SIA is used between the CHC and I/O devices. The SIA is

connected to CHC through a common bus, and is connected to an I/O

device through the RS232C or V11 interface. The SIA main from houses

a microprocessor providing a firmware control. The system control

workstation (SCWS) and may types of MODEMs can be used as I/O

devices with the FETEX-150 system. The various features of SIA are

tabulated as follows:

ITEM

I/O interface

I/O cable length

I/O Bit Rate

SPECIFICATION

RS232C

V11

15 meters (maximum)

300/600/1200/2400/4800/9600

67

Character Length

Stop Bit Length

Communication

Synchronization

VISUAL DISPLAY UNIT (VDU)

bps

7/8

bit

Full Duplex

Asynchronous/Synchronous

Fetex

It is controlled by SIA and is the most effective part of man-

machine communication. The hard copier (HP) can be connected to

VDU. The VDU displays responses to commands sent from CC through

CHC.

TEST CONSOLE (TCNS)

The TCNS consists of system maintenance part and test part. The

system maintenance part displays the operating status of system alarm,

etc. with lamps and LCD. The various tests functions it performs are :

System Supervisory

Subscriber Line Circuit Test

Trunk Circuit Test

Junction Test

Tone Check

Call Origination & Termination

Subscriber Line Test

Telephone Set Test

Howler Sending

Time Set

Call connecting procedures

Call origination

Call origination is described in the following steps:

1. When subscriber originating goes off hook, the Line Processor (LPR)

detects the change in loop state.

2. The LPR notifies the call processor (CPR) of subscriber being off hooked

using SS7 signaling system through communication protocol. The CPR

then assigns an idle time slot between the LC and digital switch module

(DSM) for the speech channel. The CPR then connects dial tones to the

line concentrator (LC) and sends a message to the LPR to begin

receiving dialed digits.

3. The LPR establishes a path between the originating and the selected

time slot, and dial tone is provided to the calling subscriber.

Digit reception

Dial pulse (DP) subscriber

The digit reception from DP subscribers is as described below

After receiving the dial tone the subscriber dials the calling subscriber number.

The dialed pulses are scanned and counted by the LPR. The corresponding

digits are transmitted to the CPR. The CPR begins the translation of the

received digits and the customer class of service. The CPR also determines the

types of call.

Dual tone multil -frequency (DTMF) subscriber

Digit reception from DTMF subscriber can be completed in three steps. If the

caller is a DTMF subscriber, a call from the line is connected to a DTMF

receiver and dial tone is returned to the line. DTMF signals are received and