subscriber switching subsystem-5

AXE 10 System Testing 1Access: PSTN, ISDN, V5Subscriber Switching Subsystem

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1. Introduction to access network 31.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2. Subscriber Switch introduction 92.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92.2 Functions in SSS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.2.1 Accesses in SSS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .112.2.2 Switching Function in SSS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122.2.3 Maintenance functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2.3 SSS in the Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142.3.1 EMG Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152.3.2 The speech path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152.3.3 The control path. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

2.4 Interworking subsystems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

3. Analogue Subscriber Access 353.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363.2 The Analogue Subscriber Access, LSM-ANSA . . . . . . . . . . . . . . 36

3.2.1 Function Units in LSM-ANSA. . . . . . . . . . . . . . . . . . . . . . . . . . . . 363.2.2 The LSM-ANSA magazine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393.2.3 Analogue Line Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403.2.4 Definition of an LSM-ANSA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

3.3 Connecting a subscriber line . . . . . . . . . . . . . . . . . . . . . . . . . . . . 433.3.1 The hardware. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 433.3.2 Subscriber number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 433.3.3 Subscriber categories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

3.4 Subscriber services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 463.4.1 Documentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

3.5 Function Blocks in ANSA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 473.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Subscriber Switch

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4. ISDN Accesses 514.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

4.1.1 Subscriber equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

4.1.2 Reference Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

4.2 Basic Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

4.2.1 Function units in LSM-BA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

4.2.2 The LSM-BA magazine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

4.2.3 Main Function Blocks for Basic Access . . . . . . . . . . . . . . . . . . . . . . . . . 56

4.2.4 Definition of an LSM-BA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

4.2.5 Connection of subscriber for BA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

4.2.6 BA-E Subscriber connection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

4.3 ISDN Primary Rate Access, PRA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

4.3.1 Function Units in LSM-PRA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

4.3.2 The LSM-PRA magazine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

4.3.3 Function blocks for PRA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

4.3.4 Connection of an LSM-PRA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

4.3.5 Connection of a PRA Subscribers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

4.3.6 PRA (E) - Connection of users . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

4.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

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1. Introduction to access network

1.1 GeneralAccess Network (AN) is a system implemented between the local exchange (LE) and the user, replacing part or the whole of the local line distribution network. The AXE supports a wide range of access products that can be deployed by network operators to meet the service, bandwidth and mobility requirements of subscribers as economically and flexibly as possible. The AN functions that comply to certain requirements of the LE are implemented in several AXE subsystems supporting the follow-ing:

• Analogue Subscriber Access, where analogue subscriber lines and ana-logue PABX are directly connected to the subscriber stage.

• Remote PSTN Subscriber Access, where analogue subscriber lines are connected via an Access Unit (AU) to the subscriber stage

• Direct PSTN Access to GSN

• AM adapted ISDN-E and non AM adapted ISDN Basic Access (BA) lines (2B+D). PSTN over ISDN BA is also supported by ISDN-E accesses.

• AM adapted ISDN-E and non AM adapted ISDN Primary Rate Access (PRA) lines (30B+D)

• V5.2 Single Link interface (PSTN and ISDN-E/ISDN BA)

• ACCESS 910

• Internet Access

The AXE access interfaces are realised in the hardware as shown below.

Subscriber Switch

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Figure 1.1Access hardware in Local Exchange, LE

The ISDN(E) accesses requires a large signalling proccesing capacity in AXE. Therefore the GAM platform is implemented to by-pass the signal-ling from the EMRPDs. The data communication in AXE is performed either through the speech channels or the signalling channel. The packet data in the subscriber D-channel are separated from the signalling data, concentrated and transmitted over semi-permanently connected BD-chan-nels to Packet Handler(s) outside AXE. The BD-channels can be also be switched or dynamically provisioned by the Packet Handler. The data communication functionality is implemented mainly in the set of part BA, PRA, V5 and FH.

As shown in the figure above, most of accesses are implemented in SSS. The digital subscriber stage concentrates and digitally multiplexes traffic from subscriber into first order PCM systems towards the digital group switch GSN. Conversion between signalling on the various types of sub-scriber accesses and the internal signalling in APT is performed in SSS hardware and software. SSS also provides operation and maintenance functions for the subscriber accesses and hardware equipment included in SSS.

The Analogue Subscriber Access, ANSA, is the part of the SSS which ter-minates analogue subscriber lines and analogue PBX lines. ANSA also contains equipment and functions to interface to the subscriber special equipment, for example, private meter and coin box.

SE

LSM

LSM

LSM

LSM

LSM

MTU

RSS

ETCETC

ETCETC

ETC

ETC

SE

LSM

LSM

LSM

LSM

LSM

MTU

CSS

ETC

CAS30B+D (PRA)

2 wire PSTN

30B+D (PRA)

V5.1/V5.2 SL

2B+D (BA)

CAS-LSM

2 wire PSTN

30B+D (PRA)

V5.1/V5.2 SL

2B+D (BA)

CAS-LSM

GSSGSS

ETC

RPG

FSK

CSK

CSR

KRDD

ACCESS HARDWARE IN LEACCESS HARDWARE IN LE

Introduction to access network

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The access may consists of units (AU) that is the equipment where ana-logue subscriber lines are remotely connected to the subscriber stage.The AU is connected to the subscriber stage via a 2048kbit/s PCM line.

The Digital PSTN access is a Direct PBX Access (DPA) to the GS. DPA is the part of the SSS handling the Private Branch Exchanges (PBX) connec-tions when the subscriber switch concentration is not required. Channel Associated Signalling (CAS) is used in the case of digital connection and DC loop signalling is used in the case of analogue connection.

The ISDN BA access is a user access towards ISDN subscribers. The BA is consists of two 64kbit/s B-channels for transmission of speech/data and one 16kbit/s D-channel for transfer of signalling information. The D-chan-nel uses a layered protocol according to ETSI.

The ISDN PRA access consists of thirty 64kbit/s B-channels for transfer of speech/data and one 64kbit/s D-channel for signalling. The D-channel uses a layered protocol according to ETSI. In the AXE, a GAM RP is used to convey the D-channel signalling to CP.

The V5 interfaces are standardised open interfaces in AXE following ETSI standards and are used for the connection of other Access Networks (AN). They use 2048 kbit/s links and in AXE Local exchange the links are connected to either the CSS or the RSS. Both PSTN and ISDN Basic Access can be connected and they can be mixed within the same V5 inter-face.

AXE supports both the V5.1 and V5.2 Single Link interfaces. Compared with V5.1, the V5.2 Single Link can also handle concentration in the access network.

Subscriber Switch

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Figure 1.2V5.1 and V5.2 SL interface in AXE

The V5 interface implementation has a structure similar to the ISDN PRA implementation. The C-channels (Communication channels) are used for signalling and are permanently connected from the LSM via the Group Switch to the Regional Processor with Group Switch interface (RPG). The RPG works as a signalling terminal for the V5 protocols, PSTN and ISDN protocols.

The RPG is connected to the Group Switch via a DL2 interface in BYB 202 while the BYB 501 realised RPG2 is connected via a DL3 line. Each LSM can have up to four V5 interfaces depending on traffic load. Existing Regional Processor Devices (RPDs) can still be used. However, RPDs cannot exist in the same pool as RPGs. Separate pools have to be defined.

ACCESS 910 is a new node offering PSTN and ISDN user connection. It is connected to the exchange via V5 interface. The reduced footprint and the open connectivity (can be connected not only to AXE but to any node offering V5.1 interface) are its main features.

The Internet Access System (IAS), Central Access Server 2.0 is the key component for the dial-up internet access. Internet is a growing part of the IT. With the rapid developments in telecommunications, it is important that network operators use the Internet to offer services to the users. Through the AXE, the following can be can achieved by the operator:

RPGRPG

RPGRPG

ETCETCRSSRSSAccessNode

AccessNode

V5.1 ORV5.2 SL

ISDN BA

PSTN

ETCETCRSSRSSAccessNode

AccessNode

V5.1 ORV5.2 SL

ISDN BA

PSTN

GSS

V 5.1 and V5.2 SL interface in AXE

Introduction to access network

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• Offering Internet services as an Internet Service Provider (ISP)

• Providing access for subscribers to other ISPs

• Allowing Internet traffic and other telecommunications traffic to com-plement one another

• Carrying Internet and other data traffic

Since the Internet traffic can cause congestion within the circuit switched network, the Internet access implementation in Ericsson is based on the separation and by-pass of the Internet traffic from telephony traffic.

The AXE -IAS-C communication is specified by a call control protocol, the Etheric 1.0.

Subscriber Switch

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Subscriber Switch introduction

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2. Subscriber Switch introduction

Figure 2.1Chapter Objectives

2.1 IntroductionThe AXE 10 Local Exchange contains, among other things, functions for different accesses and services.

The Subscriber Switching Subsystem, SSS, provides the interface between the subscribers in a fixed network and the rest of the functions in an exchange. The SSS contains hardware and software to handle normal telephony and ISDN subscriber access. Only exchanges with subscribers have an SSS; an international or a transit exchange would not normally have an SSS.

The access for the subscribers are implemented in AXE by three different subsystems:

• Subscriber Switching Subsystem (SSS) - this provide the interface between the subscriber and the rest of the exchange

• Subscriber Control Subsystem (SCS) - this coordinates traffic functions between SSS and the Traffic Control Subsystem (TCS) as well as pro-viding access to supplementary services.

This description will in primary describe the subsystem SSS.

Chapter Objectives

After completing this chapter the participant will be able to:

• Describe how SSS is implemented in AXE.

• Describe the different functions in SSS.

• Describe the structure of SSS.

Subscriber Switch

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SSS is a subsystem which interworks with many other subsystems in AXE, e.g. TCS, SCS, SUS.

Figure 2.2SSS provides the interface between the subscriber and the exchange

2.2 Functions in SSSThe Subscriber Switching Subsystem contains the following main func-tions:

• Access

• Switching

• Subscriber line signalling

• Power feed

• Concentration

• Maintenance

SSS GSS

GSSSSS

Group Switching SubsystemSubscriber Switching Subsystem


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Figure 2.3Access overview

2.2.1 Accesses in SSS SSS provides different types of access for subscribers, i.e. analogue access from Public Switched Telephony Network (PSTN), Basic and Primary Rate Access from Integrated Services Digital Network (ISDN) as well as Integrated Access. With Integretad Access Systems we mean features like Private Automatic Branch Exchanges, business cordless telephone system based on DECT (European standard), radio access system (RAS 1000) etc.

SSS

NT

PSTN

ISDN

ACCESS SWITCHING

MAINTENANCE

DIP to GSS

ISDN-PRAPABX

BA

PRA

PSTN ISDNBAPRAISDN PABX

Public Switched Telephony NetworkIntegrated Services Digital NetworkBasic AccessPrimary Rate AccessISDN Private Automatic Branch Exchange

DIPGSSSSSSPRSM

Digital PathGroup Switching SubsystemSubscriber Switching SubsystemSource ProductsRemote Subscriber Multiplexer

V5.1 interface

IAS

IAS Internet Access Server

ISDN PRA / V5 Interface

Subscriber Switch

12 03802-EN/LZM 112 20 R1

As mentioned earlier, SSS contains functions for handling different types of accesses connected to the subscriber switch. The term “access” is used to describe the interface to which the subscriber is connected. The accesses that will be discussed in this module are:

• ANSA, ANalogue Subscriber Access, POTS with analogue ordinary Telephony subscriber lines and Analogue PBX.

• BA, Basic Access (2B+D) ISDN.

• PRA, Primary Rate Access (30B+D) ISDN.

The main function of SSS when giving access to a subscriber is to set up a speech connection between two subscribers. To achieve this the digital Subscriber Switch must be able to carry out some telephony functions such as:

• Analog/Digital conversion. The conversion is performed for the sub-scribers that are analog connected to the SSS, because the Subscriber Switch is digital.

• Subscriber Line Signalling to send and receive at the Subscriber Switch. The signals are on/off hook, dial pulses, tones from keyset tele-phones, control tones e g busy tone, and ringing signals.

• Power feed is supplied by the Subscriber Switch to all subscribers that has direct access to SSS.

2.2.2 Switching Function in SSSDuring the call set-up, the subscriber is normally allocated a path from the subscriber stage to the Group Switch. This function is called switching.

Each subscriber connected to the SSS has permanent access to a channel of his own in the internal PCM system of the Subscriber Switch.


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”

Figure 2.4Switching n SSS

The subscribers speech or data can be either switched internally within the Subscriber Switch or directed towards the Group Switch. The switching functions in SSS is handled by the Time Switch unit.

One effect of the switching function is that the number of subscriber lines can be larger than the number of speech connections to the Group Swith. This is the normal circumstance in a live exchange because all subscribers connected to the SSS do not generate traffic at the same time. It saves a lot of not installed equipment and channels in the GSS.

The SSS is diveded into extension module groups (EMGs). Each EMG can access a maximum of 2048 subscribers. If the EMG is connected to the GSS with a maximum of 32 PCM lines, which together have a capacity of approximately 1000 channels , almost 50 % of the subscribers can have access to the GSS simultaneously.

SSS GSS

GSSSSS


TimeSwitch

InternalPCMSystem

ExternalPCMSystem

Pulse Code ModulationPCM

Subscriber Switch

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Figure 2.5Concentration in SSS

The Subscriber Switch concentrates traffic from many subscriber lines on two (minimum) up to 32 Pulse Code Modulation (PCM) links towards the Group Switch. In the opposite direction, from GSS to the subscriber lines, the traffic is expanded.

The PCM lines between the Subscriber Switch and the Group Switch are called System Lines.

2.2.3 Maintenance functionsThe maintenance function in SSS supervises all internal and external SSS interfaces and the time switches (which are included in the switch func-tion).

For the Switching function, some function blocks in SSS handle supervi-sion of the Time Switches. These blocks analyse the error signals which are sent from the hardware, initiate automatic blocking of fault suspected units as well as sending of alarms and handling of command initiated tests. These function blocks are not particular to the type of access in SSS.

There are maintenance and management function groups responsible for each type of access. Each group consists of a set of function blocks taking care of a specific access type (see figure 1.4). One of the main functions of these management blocks is to handle the testing of subscriber lines.

SSS

GSS

GSSSSS


EMGMax 2040PSTNSubscribers

Min. 2, and up

EMG Extension Module Group

to max24E1 Links


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Figure 2.6Function Groups for Maintenance of the accesses in SSS

ANSA MANSA

BA MBA

PRA MPRA

Access Functions Maintenance Functions

ANSABAPRA

MANSAMBAMPRA

Analogue Subscriber AccessBasic AccessPrimary Rate Access

Maintenance for ANSAMaintenance for BAMaintenance for PRA

Subscriber Switch

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2.3 SSS in the Network One of the requirements of SSS is that the size of the subscriber switch must be variable, therefore the whole Subscriber switch has been divided into modules. These modules are called Extension Module Groups (EMGs). The number of EMGs connected to the exchange depends on the number of subscribers and type of accesses. When the exchange is installed, or extended by more EMGs, the EMGs are given names that reflect their location.The EMGs are connected to the Group Switch by means of PCM links (2 Mbit/s).

As the figure below shows, EMGs can be located in two different ways in the network:

• Centrally located, close to the Group Switch, in the exchange. In this case it is called Central Subscriber Switch (CSS) or Local Subscriber Switch (LSS).

• Remotely Located, at a distance from the exchange. In this case it is called Remote Subscriber Switch (RSS).

Figure 2.7Location of EMGs

GSS

CSS-0 SSS

EMG

AXE Local Exchange

PCM

CSS-n

EMGRSS-0

EMG

RSS-n

EMG

PCM

PCM

EMGCSSRSS

Extension Module GroupCentral Subscriber SwitchRemote Subscriber Switch

PCMGSSSSS

Pulse Code ModulationGroup Switch SubsystemSubscriber Switch Subsystem


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2.3.1 EMG StructureOne EMG consists mainly of Switch Modules for different types of accesses, both analogue and digital access. These modules are called Line Switch Modules, LSMs. In addition, equipment for testing the subscriber lines and special equipment for e.g. private metering can also be found in an EMG.

Types of magazines in an EMG are:

• Line Switch Modules for Analogue Subscriber Access, LSM-ANSA.

• Line Switch Modules for Basic Access, LSM-BA.

• Line Switch Modules for Primary Rate Access, LSM-PRA.

• Extension Switch Modules for integrated Accesses, Source Products and Remote Subscribers Multiplexers.

• Special Equipment magazines for i.e. Coin Box and Private Metering.

• Subscriber Line Tester, SULT.

An EMG can be equipped with a combination of different types of LSM, SULT and Special Equipment. See an exampel in the figure below.

Figure 2.8LSM in an EMG

LSM-ANSA

LSM-BA

LSM-PRA

ESM

SE

SULT /MTU

EMG

Subscriber Switch

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An EMG can be equipped with 32 LSMs. The first 16 (0 to15) are reserved for the telephony accesses like ANSA, BA, PRA etc. However, LSMs numbered from 16 to 31 are reserved for special equipment.

2.3.2 The speech path

The Time Switch

The Switching in SSS is handled by the Time Switch, TS, function. In each LSM there is an Extension Module Time Switch (EMTS) allocated on a PCB called TSW.

In the Time Switch, speech samples from the different kinds of the sub-scriber’s Line Interface Circuits (LIC) are connected to a free channel in a PCM line to the Group Switch in outgoing calls.

As mentioned earlier, the Time Switch concentrates the traffic to the Group Switch and all LSMs does not necessarily have an “own” PCM line to the Group Switch. The switching in this case will be handled by the local TSs, using the Time Switch Bus (TSB) to reach an LSM magazine that is connected to the Group Switch with a PCM line. See figure below where calls from ISDN Private Automatic Branch Exchange must be switched to the Group Switch through one of the other to LSM magazines.

In case of traffic between subscribers connected to the same EMG, no con-nection to the Group Switch is necessary. The switching will again be han-dled by the local TSs, using the Time Switch Bus (TSB) to get the LSM where the other subscriber is connected. However, the Group Switch pro-vides additional supervision of speech and therefore most operators choose to have their calls routed through the Group Switch anyway.


03802-EN/LZM 112 20 R1 19

Figure 2.9Switch Functions in an EMG

Synchronization of an EMG

All LSMs within an EMG have to be synchronized to each other and to the Group Switch. Therefore each TSW also contains a clock, an oscillator, which generates clock pulses used in synchronization of the Time Switch and other buses. This is handled by the function block Clock Distribution (CD).

The TSWs are synchronised towards the Group Switch by defining two TSWs as Master Clocks. One TS is Master Executive and the other is Master Stand-by.

TSW JTC/ETB

Switch Functions

To GSS

TSB

LIC

BA

TSW JTC/ETBDLIC

PRA

TSW JTC/ETBETP

PCM

ACCESS

DLIC

LIC

ETP

ANSA

ISPABX

LSM

LSM

LSM

ANSABAPRAPRAIS PABX

Analogue Subscriber AccessBasic AccessPrimary Rate AccessPrimary Rate AccessISDN Private Automatic Branch Exchange

LICDLICETPTSWTSB

Line Interface CircuitDigital Line Interface CircuitExchange Terminal PRATime SwitchTime Switch BusJunctor Terminal CircuitExchange Terminal Board

JTCETB

GSSLSM

Group Switch SubsystemLine Switch Module

Subscriber Switch

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In a Remotely Located Subscriber Switch the incoming synchronization information is sent over channel 0 in the 32 channel PCM line from the Group Switch, see figure below. The Master Clock then synchronizes the Master-SB and all Slave TSWs within the same EMG by using the TSB. See figure below.

Figure 2.10Synchronization of a Centrally Located EMG

The Master-SB oscillator can be switched over to Master-Ex status auto-matically in a fault situation or manually by command EXTBC.

The Time Switch Bus

The Time Switch Bus, TSB, connects all the Time Switches in an EMG. The TSB is duplicated into TSB-A and TSB-B. One of the buses, A or B, is “executing“ and the other is “stand-by”. The bus carries mainly speech information. To print the state of the TS and the TSB command STSTP is used, see figure below.

TSW

Master(EX)

TSW

Master(SB)

TSW

Slave

TSB

LSM-0 LSM-1 LSM-15

CDCDCD

ETB ETB

PCM, Synchronization signals on time slot 0 from GSS

8 kHz Synchronization from Master Clock

Exchange Terminal boardTime Switch Bus

ETBTSB

LSMTSW

Line Switch ModuleTime SwitchClock DistributionCD


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Figure 2.11Printout of command STSTP

The Device Speech Bus

Almost all units in the LSM are connected to the TSW via a bus. This bus is referred to as the DEVSB (Device Speech Bus). The DEVSB is divided into two branches, DEVSB-0 and DEVSB-1. These buses are in the back plane of the LSM. The figure below shows an example of units connected to the TSW by DEVSB in an LSM-ANSA.

<STSTP:EMG=LSS0,EMTS=ALL;

DISTRIBUTED SWITCH STATE SURVEY TSB DATA EMG TSB TSBSTATE TSBBLS LSS0 TS-A SB TS-B EX EMTS DATA EMG EMTS EMTSSTATE EMTSBLS EMTSCLSTATE GSCONN LSS0 TS-0 WORKING M-EX YES TS-2 WORKING SLAVE YES TS-4 WORKING SLAVE NO END

Subscriber Switch

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Figure 2.12The speech buses

In the figure above we can see the advantage from using different speech buses, the DEVSB-0/1 and theTSB. If the subscriber connected to LSM-15 wants to be connected through the Group Switch, there is no PCM line to the GSS. As mentioned earlier, the speech sample will be connected through the local Time Switch, via the TSB to a LSM magazine equipped with a PCM line. But what happens when the same subscriber lifts his handset?

LIB

LIB

TSW

LIB

LIB

KRC

SLCT

ETB/JTC

DEVSB-0

DEVSB-1

PCM to GSS

TSB-A

TSB-B

TSW

KRC

SLCT

ETB/JTC

ETB/JTC

DEVSB-0

DEVSB-1

TSB JTCTime Switch Bus Junctor Terminal Circuit

LIBLIB

LIBLIB

LSM-0

ETB/JTC

LSM-15

Time SwitchDevice Speech BusExchane Terminal BoardLine Interface Board

TSWDEVSBETBLIB

Line Interface CircuitSubscriber, Line and Circuit TesterKeyset code Receiver Circuit

LICSLCTKRCLSM Line Switch Module


03802-EN/LZM 112 20 R1 23

The Keyset code Receiver Circuit (KRC) is used for receiving tones from keyset telephones, and that PCB is also missing in LSM-15. Normally when a subscriber with a keyset telephone lifts his handset, the subscriber is connected to a KRC, which will receive the digits.

The KRC contains eight individuals and these individuals can receive dig-its from eight subscribers simultaneously. Each Line Switch Module (LSM) can be equipped with one KRC board each, although the traffic volume does not normally require KRC boards in all LSMs.

When a LSM is not equipped with a KRC board, the subscribers will be connected to KR individuals in another LSM magazine via the Time Switch Bus. The same thing will happen if all KR individuals in a particu-lar Line Switch Module are occupied.

2.3.3 The control path

EMRP/EMRPD

The control of the EMG is arranged into Extension Modules (EMs). Each LSM is defined as an EM. These Extension Modules, called EMRP or EMRPD in case of an LSM-BA, control the hardware units in each LSM and Special Equipment magazine.

The EMRP/EMRPD contains regional software for the blocks that have hardware inside the LSM magazine.The EMRP states can be printed by command EXEPP and the regional software can be printed by command EXEDP (figure 1.11).

Figure 2.13Printout of the command EXEPP

<EXEPP:EMG=LSS0,EM=ALL; EMGEM PROCESSOR CONTROL STATE EMG EM PROCESSOR TYPE PATH STATE MAINT.STATE LSS0 0 A EMRP3 A WORKING-EX IDLE 2 A EMRPD1 A WORKING-EX IDLE 4 A EMRP3 A WORKING-EX IDLE 16 A EMRP3 A WORKING-EX IDLE END

Subscriber Switch

24 03802-EN/LZM 112 20 R1

Figure 2.14Printout of command EXEDP

There are four different LSMs defined in the Extension Module Group (EMG) called LSS0 as seen in the two printouts above. All regional proc-essors, EMRP and EMRPD, is working normally. The first EM is EMRP-0 and the type of processor is an EMRP3. The magazine is an ordinary LSM-ANSA with analogue subscribers connected to Line Interface Cir-cuits since the regional software LIa1R is loaded.

The second EM, EMRP-2, has another processor called EMRPD1. The last letter D stands for digital and the processor uses regional software pro-

EMGEM SOFTWARE UNIT AND EQUIPMENT DATA EMG LSS0 EM SUNAME SUID EQM 0 TEETR 2/CAA 117 067/1 C R1A01 EMGFDR 1400/CAA 117 054/1I R2A01 REPER 1000/CAA 117 081/1K R3A02 CDR 1D11/CAA 117 1062/M57A R2A01 CD-0 JTR 1D11/CAA 117 1036/M57A R3A01 JT-0&&-63 KR2R 1DAB/CAA 117 1154/M83E R3A02 KR2-0&&-7 LIA1R 1966/CAA 117 1173/M83G R2A09 LI-0&&-127 SLCT1R 1969/CAA 117 1159/M83G R3A04 SLCT-0 SULAR 1D11/CAA 117 1100/M57D R2A03 SULA-0&&-127 SEPRMIR 1D11/CAA 117 1150/M57A R2A02 SEPRMI-0&&-127 SSTONER 1966/CAA 117 1141/M83G R3A07 SSTONE-0 TSR 1966/CAA 117 1209/M83G R2A01 TS-0 2 EMGFDR CAA 140 001 R4A02 EDEXR CAA 140 006 R7A50 LIBAR 303/CAA 147 001/M57F R8A02 LIBA MHBAR 304/CAA 147 026/M57L R2A01 MHBA-0 MANBAR 966/CAA 147 013/M83E R5A01 MANBA-0 SLQCTR 300/CAA 147 005/M57B R2A01 SLQCT STL2R 500/CAA 140 105/M57L R4A/1 STL2 TSR 966/CAA 147 028/M83E R1A02 TS-2 CDR 300/CAA 147 021/M57H R2A04 CD-1 JTR 300/CAA 147 027/M57D R1A02 JT-128&&-191 SSTONER 966/CAA 147 003/M83E R3A06 SSTONE-2 FHLR 500/CAA 140 103/M57L R2A03 FHL-0 4 TEETR 2/CAA 117 067/1 C R1A01 EMGFDR 1400/CAA 117 054/1I R2A01 REPER 1000/CAA 117 081/1K R3A02 TSR 1966/CAA 117 1209/M83G R2A01 TS-4 CDR 1D11/CAA 117 1062/M57A R2A01 CD-2 LIPAR 1D11/CAA 117 1183/M57K R3A01 LIPA-0&&-127 STR 1DAA/CAA 117 1212/M83C R1A04 ST-0&&-3 ETPRAR 1304/CAA 117 1187/M83G R2A05 ETPRA-0&&-3 SSTONER 1966/CAA 117 1141/M83G R3A07 SSTONE-4 16 TEETR 2/CAA 117 067/1 C R1A01 EMGFDR 1400/CAA 117 054/1I R2A01 REPER 1000/CAA 117 081/1K R3A02 ACCSDR 1D11/CAA 117 1092/M57A R1A04 ACCSD-0 HOWLR 1D11/CAA 117 1013/M57A R2A02 HOWL-0&&-3 SULTDR 1D11/CAA 117 1121/M57A R2A02 SULTD-0 END

<EXEDP:EMG=LSS0,EM=ALL;


03802-EN/LZM 112 20 R1 25

grammed in language C++. The magazine is a LSM-BA, Basic Access (2B+D) with ISDN subscribers connected to the Digital Line Interface Circuits. The regional software that gives this access is called LIBAR.

The third EM, EMRP-4, is a LSM-Primary Rate Access magazine (30B+D) that connects the ISDN Private Automatic Branch Exchanges via a 32 channel PCM link to the PCB ETP (Exchange Terminal PRA). The regional software that givis this access is called ETPRAR.

The last EM, EMRP-16, is a Subscriber Line Tester magazine. This maga-zine performs automatic subscriber line tests or tests initiated by com-mand.

Device Processor

EMRP/EMRPD communication with the CP use standard operation and test points. These are a set of operation points which tell the CP what state the EMRP is in. This data is checked at regular intervals. When changes are made the operation points are correspondingly changed.

Subscriber Switch

26 03802-EN/LZM 112 20 R1

Figure 2.15EMRP connection

When ordering changes in operation points, i.e. subscriber lifts the hand-set, when additional hardware or other changes are detected, the Device Processors (DP) in the LSM assist the EMRP. There is one DP per circuit board in the LSM (except for the Ringing Generator Unit, REU, and the Power Units, POU, which do not have DP) that handles the units located on that board. The DP contains a simple program which is only capable of analysing changes in the hardware. Each change is reported to the EMRP. The Device Processors are connected to the EMRP by means of the DEVCB.

The Extension Module Regional Processor Bus

The EMRPs in an EMG are all connected to two Extension Module Regional Processor Buses, EMRPB-A and EMRPB-B. The EMRPBs are connected to either an RPBC, Regional Processor Bus Converter, or an

EMRP

EMRPB-A

EMRPB-B

DP

DP DP

DEVCB

RPBC / STRP

LIB-15 TSW ETB/JTC

SLCT KRC

DPLIB-0

DP

DP

EMRP

DP

DP DP

DEVCB

LIB-15 TSW ETB/JTC

SLCT KRC

LSM(EM=15)

DPLIB-0

DP

DP

POUREU

REU POU

LSM (EM=0)

EMRP JTCExtension Module Regional Processor Junctor Terminal CircuitExtension Module Regionl Processor BusDevice Control BusRegional Processor Bus ConverterSignalling Terminal Remote Processor

EMRPBDEVCBRPBCSTRP

Line Interface CrcuitSubscriber, Line and Circuit TesterKey Set Receiver

LICSLCTKRCTSW Time Switch

Extension ModulePower Unit

EMPOU

Line Interface BoardLIBRinging Generator UnitREU

LSM Line Switch Module


03802-EN/LZM 112 20 R1 27

STRP, Signalling Terminal Remote Processor. This depends on whether the EMG is centrally or remotely located. The main task of the RPBC and the STRP is to convert the format of the signals from one bus to a format used on another bus.

RSS Control

The Signalling Terminal Central (STC) is located in the local exchange. The Signalling Terminal Remote Processor(STRP), located in the RSS site as a PCB in the LSM magazine. In older applications the signal conversion toke place in a magazine called Signalling Terminal Remote (STR) but is today replaced with the STRP. The STRP is used for processing the con-trol signals between the EMRPs in the Remote Stage and the STC/CP in the parent exchange. The EMRP communicates with the CP on channel 16 in a 32-channel PCM system. For security reasons the control sihnalling link (CLC) is duplicated.

The information that is sent on these CLCs includes register signals, main-tanence information, loading of regional programs in EMRPs program store, etc.

The control signalling path from the CP to an RSS when signalling con-version is implemented in the LSM magazine is as follows:

CP- STC - ETC- PCM (time slot 16)- ETB- STRP- EMRPB- EMRP

The control path for an RSS using STRP is illustrated in the figure below.

Subscriber Switch

28 03802-EN/LZM 112 20 R1

Figure 2.16The control path between CP and RSS

EMRP

EMRPB-A/B

EMRP

STR

CP-ACP-B

RPB-ARPB-B

GSS

EMRP

ETB

STC STC

16

PCM LINK

PCM LINK

LSM

LSM

LSM

16

RSS

ETB ETC

EMRP ETBExtension Module Regional Processor Exchange Terminal BoardExtension Module Regionl Processor BusEMRPB

STRP Signalling Terminal Remote ProcessorSTC Signslling Terminal Central

Exchange Terminal CircuitCentral Processor A sideCentral Processor B side

ETCCP-ACP-BRPB Regional Processor BusLSM Line Switch Module

Pulse Code ModulationPCM Remote Subscriber SwitchRSS

STC-G STC-G

ETC


03802-EN/LZM 112 20 R1 29

CSS control

In the Central Subscriber Stage STRP and STC are combined into one unit called the Regional Bus Converter (RPBC). The communication between the CP and the EMRPs will take the following path:

CP - RPB - RPBC - EMRPB - EMRP

This is illustrated in the figure below.

In the CSS there is no transfer of control signals over the PCM links and all channels on the link can be used for traffic.

Figure 2.17The control path between CP and CSS

EMRPB-A/B

RPBC

CP-ACP-B

RPB-ARPB-B

GSS

EMRP

JTC

EMRP

JTCPCM

CSS

LSM

LSM

LSM

PCM

EMRP JTCExtension Module Regional Processor Junctor Terminal CircuitExtension Module Regionl Processor BusEMRPB

RPBC Regional Processor Bus ConverterCSS Central Subscriber Switch

Line Switch ModuleCentral Processor A sideCentral Processor B side

LSM CP-ACP-BRPB Regional Processor BusPCM Pulse Code Modulation

Group Switching SubsystemGSS

EMRP

Subscriber Switch

30 03802-EN/LZM 112 20 R1

The Control Signalling Link

The control path between the STRP and the STC, and between the RPBC and the EMRP, is handled by means of a software EM module in the STC/RPBC. It is referred to as the Control Signalling Link, CLC. The CLC is always defined as EM=1.

Some useful printout commands are shown in the figures below.

Figure 2.18Printout of command EXEGP

Figure 2.19Printout of command EXEMP

Figure 2.20Printout of command EXCLP

<EXEGP:EMG=ALL;

EMG DATA EMG TYPE SIDE RP LINK ST STR TYPE MAST EMGNUM RSS0 REMOTE A 52 CLC-2 WO STR2C IDLE 1 REMOTE B 56 CLC-3 BL STR2C IDLE 1 LSS0 CENTRAL A 32 CLC-0 WO RPBC2C IDLE 0 CENTRAL B 33 CLC-1 WO RPBC2C IDLE 0 END

<EXEMP:RP=52,EM=ALL; EM DATA RP TYPE EM EQM TWIN CNTRL PP STATE 52 STC2C 1 CLC-2 PRIM WO END

<EXCLP:EQM=ALL;

CONTROL SIGNALLING LINK DATA

EQM STATE RPADDR DEV SPEED

0 WORKING 32 64

1 WORKING 33 64

2 WORKING 52 RT-16 64

END


03802-EN/LZM 112 20 R1 31

2.4 Interworking subsystemsThe Subscriber Switching Subsystem interworks with many subsystems in AXE. The most important of them are:

• SCS, Subscriber Control Subsystem, for traffic control and Traffic administration of supplementary service functions for subscribers con-nected to SSS. The main task is to handle the traffic control functions while SSS is to handle the connection functions. At an earlier stage SSS had both functions. SSS became to large and that is the reason why SSS was split in two parts; SSS and SCS. Some of the function blocks in SCS will further on be presented in the chapters Analogue Subscriber Access and ISDN Access .

• SUS, Subscriber Services Subsystem, for provision of subscriber serv-ices.

• TCS, Traffic Control Subsystem, for traffic handling and administra-tion to and from the SSS.

• GSS, Group Switch Subsystem, for connection and disconnection of originating or terminating speech paths from or to the SSS.

• OMS, Operation and Maintenance Subsystem, for handling operation and maintenance.

• STS, Statistics and Traffic Measurement Subsystem, for collection of statistics.

• CHS, Charging Subsystem, for charging purposes and activation of

Subscriber Switch

32 03802-EN/LZM 112 20 R1

subscriber charging purposes.

Figure 2.21Interworking Subsystems with SSS

2.5 Summary• SSS provides different types of access for subscribers, i.e. analogue

access (PSTN), Basic and Primary Rate Access (ISDN).

• The subscribers speech or data can be either switched internally within the subscriber switch or directed towards the group switch

• The switching functions in SSS is handled by the Time Switch unit.

• The maintenance function in SSS supervises all internal and external SSS interfaces and the Time Switch units.

• The Subscriber Stage is built of a number of Extension Modules Groups (EMG).

• An EMG can be centrally (CSS) or remotely (RSS) located.

• An EMG consists of Line Switch Modules (LSM). In addition, equip-ment for testing the subscriber lines and special equipment for e.g. pri-vate metering can also be found in an EMG.

• The TSB (Time Switch Bus) connects all the Time Switches in an EMG.

• The DEVSB (Device Speech Bus) connects all units involved in the

OMS STS

CHS

GSS

SCS

SUS

TCS

SSS

SSS SUSSubscriber Switching Subsystem Subscriber Services SubsystemCharging SubsystemGroup Switch SubsystemTraffic Control Subsystem

CHSGSSTCS

Subscriber Control SubsystemStatistics and Traffic Measurement SubsystemOperation and Maintenance Subsystem

SCSSTSOMS


03802-EN/LZM 112 20 R1 33

speech path in the LSM.

• The control of the EMG is arranged into EMRP/EMRPD. The EMRP/EMRPD contains regional software for the blocks that have any hard-ware inside the LSM magazine.

• The EMRPB (Extension Module Regional Bus) connects all EMRP/EMRPDs in an EMG.

• The control path from the CP to an RSS is: CP - STC - ETC - PCM -ETB - STRP - EMRPB - EMRP.

• The control path from the CP to an CSS is: CP - RPB - RPBC - EMRPB - EMRP.

• The Control Signalling Link is the link between the STC and STRP in an RSS and the link within the magazine RPBC in a CSS.

Subscriber Switch

34 03802-EN/LZM 112 20 R1

03802-EN/LZM 112 20 R1 35

3. Analogue Subscriber Access


Chapter Objectives


• Describe the hardware of LSM-ANSA.

• Connect an LSM-ANSA in the exchange.

• Connect an analogue subscriber.

• Change a subscriber’s categories.

Subscriber Switch

36 03802-EN/LZM 112 20 R1

3.1 Introduction This chapter describes the analogue subscriber access which includes:

• Hardware structure of LSM-ANSA.

• Connection of an LSM-ANSA.

• Connection of ordinary analogue subscriber line.

• Change of subscriber categories.

• Analogue Private Branch Exchange, PBX.

Figure 3.2The analogue subscriber access.

3.2 The Analogue Subscriber Access, LSM-ANSA

3.2.1 Function Units in LSM-ANSAAnalogue subscriber lines for both Public Ordinary Telephony Subscribers (POTS) and analogue Private Branch Exchanges (PBX) are connected to Line Interface Circuits (LICs) allocated on Line Interface Boards (LIB) or Analogue Line Boards (ALB) in the LSM Magazine, see figure above.

A maximum of 128 LICs can be housed in the LSM-ANSA. An EMG can have a maximum of 16 LSMs reserved for subscribers. This means that a maximum of 2048 analogue subscriber lines can be connected to one EMG (fully equipped with LSM-ANSAs only).

2 wires

EMG (CSS/RSS)

PBX

LSM-ANSA

LSM-ANSA

Max. 128

Analogue subscriberLines/LSM

LSM-0

LSM-15

LIB

LIB

ALB

ALB

Analogue Subscriber Access

03802-EN/LZM 112 20 R1 37

The LICs are allocated either on Line Interface Boards (LIBs) or Analogue Line Boards (ALBs). The type of boards depend on the variant of the LSM magazine, which will be discussed later in this chapter.

The hardware of LSM-ANSA consists of many hardware units (PCBs) which offer different functions. The main units and their functions are described in the text below.Note that the ETB/JTC and the KRC are optional units, and that STRP only can be implemented in a remotely installed LSM.

Figure 3.3The hardware of an LSM-ANSA

1. TSW, Time Switch

This switch is a digital time switch and all the telephony units in the LSM, as well as the Time Switch Bus, are connected to the switch. The Time Switch has got 768 inlets and outlets since there are 512 channels on the Time Switch Bus and 128 channels on each Device Speech Bus. This Time Switch is also called Extension Module Time Switch (EMTS) and is congestion-free. It also contains functions for generation of tones and attenuation of audio signals (e.g. attenuation of tones).

2. Clock

The clock in the LSM supplies the internal buses and the Time Switch with synchronization. The clocks are synchronized from the Group Switch

LIC0&&3

LIC4&&7

LIC124&&127

TSW

KRC

ETB

STRP

EMRP

SLCT

REU POW

LSM

Subscriber Switch

38 03802-EN/LZM 112 20 R1

and consist of a voltage controlled oscillator. The clock is located on the TSW PCB.

3. ETB or JTC

ETB, Exchange Terminal Board, is used if the subscriber switch is used as a Remote Subscriber Switch, RSS. This board is the interface towards the PCM line and it contains functions similar to the ones in an ordinary ETC.

JTC, Junctor Terminal Circuit, is the interface towards the Group Switch if the subscriber switch is installed locally. These units, ETB or JTC, are connected to the Time Switch. In each LSM, up to two ETB/JTC can be installed and each are connected to a 32 channel PCM.

4. KRC, Keyset code Reception Circuit

This unit is connected to the Time Switch and it is used to receive the dig-its when sent from keyset telephones. The number of KRCs per EMG depend on the number of push buttom telephones. For the LSMs not hav-ing a KRC of their own, the Time Switch Bus can be used to connect the subscribers with an idle KRC in another LSM as was described earlier.

5. LIC, Line Interface Circuit

Up to 128 LICs can be housed in one LSM magazine. The LICs are con-nected to the TSW via the two internal speech buses, DEVSB-0 and DEVSB-1. The LICs are allocated either on Line Interface Boards (LIBs) or Analogue Line Boards (ALBs). A more detailed description of the dif-ferent units at the ALB will be presented further on in this chapter.

6. REU, Ringing Generator Unit

In each LSM, there is a Ringing Generator which generates the ringing current towards the subscriber. The Ringing current is connected to the subscriber line via a relay in the Line Interface Circuit.

7. SLCT, Subscriber Line and Circuit Tester

This unit is responsible for various tests of the subscriber lines and the LICs in the LSM. The SLCT can be connected to the Line Interface Cir-cuits via a relay on the LIC. Both routine and command-initiated tests are performed by the SLCT.

8. EMRP, Extension Module Regional Processor

The EMRP is the controlling and processing unit in the magazine. It con-tains regional software units to all the blocks that have any hardware in the LSM . In addition, the EMRP contains software for various APZ functions (e.g. operating system software and the fault detection in the EMRP).

9. STRP, Signalling Terminal Remote Processor

The STRP is responsible for the handling and transferring of control sig-nalling information such as charging info, operation and maintenance etc. It is data transferred between the remote unit and the host.

10. Power unit


03802-EN/LZM 112 20 R1 39

The power unit in the LSM magazine converts the -48V, distributed from the rack, to the required voltage (+5V, -5V and +12V).

3.2.2 The LSM-ANSA magazineThere are different generations of SSS and of the LSMs for analogue sub-scriber access.

The latest generation of the subsystem is called SSS-5 and provides a mix-ture of POTS and ISDN accesses. This version improve the performance and flexibility to the customer. SSS-5 can be used in metropolitan as well as rural areas and is compatible with the present version of SSS (SSS-4)

The older LSM generation (SSS-4) have two variants of the magazine, depending on the type of Line Interface Circuits used. In one variant there are 4 LICs per board and in the other 8 LICs per board. It is most common to use eight LICs. This means either 16 or 32 LIBs can be housed in one magazine.The figure below shows the structure and the connections of the magazine.

.

Figure 3.4LSM magazine for SSS-4

The size of this magazine is 24 Building Modules (BM), about 0.98 meter long. This is housed in one shelf of a cabinet.

TSB-A/B

TS

W

LIB

-0

KR

C

LIB

-1

LIB

-15(

or 3

1)

SLC

T

ET

B/J

TC

ET

B/J

TC

EM

RP

PO

UTest Bus

RE

U

EMRPB-A/B

- 48V

to STR

TSW Time Switch KRC Keyset code Receiver CircuitLIB Line Interface BoardSLCT Subscriber Line Circuit Test JTC Junctor Terminal Circuit

ETB Exchange Terminal Board EMRP Extension Module Regional ProcessorSTR Signalling Terminal Remote REU Ringing Equipment UnitPOU Power Unit

Subscriber Switch

40 03802-EN/LZM 112 20 R1

The latest LSM generation (for SSS-5) is the ACA3 magazine which includes private meter functions fully integrated into the magazine. This means that the SEPRM magazine is no longer needed. The whole maga-zine uses only 12 1/2 BM, which allows two magazines in one shelf.

Figure 3.5LSM magazine for SSS-5, ACA3

A new line board, ALB (Analogue Line Board), has been developed for the ACA3 magazine. Eight subscriber lines are terminated on each board. There are 16 board positions in the magazine which allow a maximum of 128 subscribers to be connected. See figure 2.5.

In addition it is also possible to house one STRP board (Signalling Termi-nal Remote) into the magazine. The STRP is a compact version of the STR magazine which consists of several PCBs.

3.2.3 Analogue Line BoardThe Analogue Line Board (ALB) contains equipment for eight subscrib-ers. Part of the equipment is individual to each of the eight subscribers and part is common to all eight. The individual part is called Line Circuit.

The following functions are implemented on the Analogue Line Board:

• DC-signalling, that is detection of on hook and off hook states, receive

TSB-A/B

TS

W

ALB

-0

KR

C

ALB

-1

ALB

-15

SLC

T

ET

B/J

TC

ET

B/J

TC

EM

RP

ST

RP

PO

U

Test Bus

RE

U

EMRPB-A/B

- 48V

TSW Time Switch KRC Keyset code Receiver Circuit ALB Analogue Line Board (with Private Meter) SLCT Subscriber Line Circuit Test JTB Junctor Terminal Board

ETB Exchange Terminal Board EMRP Extension Module Regional Processor STRP Signalling Terminal Remote ProcessorREU Ringing Equipment Unit POU Power Unit


03802-EN/LZM 112 20 R1 41

and decade pulses from dial telephones

• Ring tripping

• Analog/Digital and Digital/Analog conversion, A/D and D/A

• Programmable current feeding

• Overvoltage protection

• Test functions

• Supervision of the subscriber line

• Private metering

Test Relay

This relay is used to connect the subscriber line or the Line Circuit to the functions implemented on the Subscriber Line and Circuit Tester (SLCT). It is done via an internal test bus and the regional software of SLCT per-forms different routine tests for selected subscriber.

Ring Reley

This relay connects the subscriber lines to the Ringing Equipment Unit (REU), which is a ringing generator. The relay is controlled by the Micro-processor which is common for all eight subscribers.

Overvoltage protection

Each Line Circuit has a device which protects it against overvoltage. The protection device uses self healing fuses.

Ericsson Subscriber Line Interface Circuit

Each subscriber has an individual ESLIC, Ericsson Subscriber Line Inter-face Circuit. The functions implemented in the ESLIC are detecting on hook and off hook states, ring tripping, receiving dial pulses etc.

Ericsson Analogue Converter

The EAC, Ericsson Analogue Converter, is used for A/D and D/A conver-sion, controlling the ESLIC circuit and for 2/4 wire conversion.

The Line Circuit receives analog speech signals from the two-wire sub-scriber line, but since digital systems are four wire, the two-wire circuit must be converted to a four wire circuit before the A/D conversion can take place.

Ericsson DC-converter

One EDC, Ericsson DC-converter, is used for 4 subscriber lines for pro-grammable regulation of the line feeding voltage.

Ericsson Signal Processor

One signal processor ESP, Ericsson Signal Processor, is common for all lines. All necessary digital filtering and processing is performed in the ESP.

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42 03802-EN/LZM 112 20 R1

Micro Processor

The micro processorcontrols and supervises all lines and functions on the Analogue Line Board.

3.2.4 Definition of an LSM-ANSA When the hardware installation and cabling of the LSM magazine has been completed, the definition of the exchange data for the LSM has to be specified. The exchange data will tell the system what software programs to load in the EMRP and what type of equipment is contained in our LSM.

The Operational Instruction “Addition of LSM in EMG” should be used. The document assumes that the EMG has been defined. If not, the OPI “Connection of an EMG” should be followed.

In the text below the procedure for definition of an LSM-ANSA is described.

1. Definition of an Extension Module Regional Processor, EMRP.

EXEPI:EMG=emg,EM=em,TYPE=EMRP3,CONTROL=single;

2. Loading of regional software in EMRP. The command has to be repeated for each software unit that is to be loaded.

EXEUI:EMG=emg,EM=em,SUNAME=suname;

EMG Name of extension module group EM Number of extension module SUNAME Software unit name

3. Definition of equipment. The command has to be repeated for each different type of equipment that is to be connected.

EXEEI:EMG=emg,EM=em,EQM=eqm;

EMG Name of extension module group EM Number of extension module EQM Equipment

When the data is defined, the equipment the LSM magazine should be tested and deblocked (put to work).


03802-EN/LZM 112 20 R1 43

3.3 Connecting a subscriber lineThe subscriber’s connection to AXE exchange consists of both a hardware and a software part. Once the hardware is installed, it is very seldom changed. The hardware connection does not affect the subscriber number, which is stored in a software record. Thus a subscriber’s number can very easily be changed.

3.3.1 The hardware

What kind of equipment is absolutely necessary when a new subscriber is to be connected? From the hardware point of view, the following is needed:

• a phone set

• a line to the exchange

• a LIC individual.

Figure 3.6Subscriber-related hardware

The subscriber’s telephone set is connected via a cable to the Main Distri-bution Frame (MDF) where all the incoming cables are organized before being connected to the switch. The MDF has direct lines to the subscriber switch and each connection is terminated at the Subscriber Stage by the Line Interface Circuit (LIC). Each subscriber corresponds to one LIC. There are up to eight such circuits on one printed board assembly (Line Interface Board, LIB), see figure 2.6.

3.3.2 Subscriber numberA subscriber can be allocated any subscriber number within the exchange number series. The preconditions for this, however, are that the number has been defined as an internal number in the exchange and that it is vacant. Internal numbers are specified in groups of a hundred, where each group has its own number, a so-called “hundred-number”. Either one or

LIC

SS

MDF

Subscriber Switch

44 03802-EN/LZM 112 20 R1

ten groups can be specified at a time. The hundred-number is specified by command and does not need to have the same value as the hundreds digit.

Example

The subscriber numbers 201000-201099 can be given the hundred-number 4, and 201100-201199 the hundred-number 5.

The commands for these specifications of number series are:

EXNSI:SNB=201000,HU=4;

EXNSI:SNB=201100,HU=5;

If the hardware has been connected and a subscriber number is vacant, a subscriber can be connected to a LIC by means of one single command, SULII .

SULII:SNB=snb,DEV=dev;

As soon as a subscriber is disconnected (with the command SULIE) all extra categories will disappear and only the standard categories will remain. Consequently, when a subscriber gets a new number, the catego-ries will have to be specified anew. Therefore, a printout of the existing categories is always done (command SUSCP) before any kind of changes are implemented.

3.3.3 Subscriber categoriesSubscriber categories contain a characteristic linked to a subscriber number. The categories affect the handling of calls to and from this sub-scriber.

The categories specify:

• Subscriber line characteristics, which describe the subscriber’s line equipment.

• Subscriber characteristics, which give the subscriber special authoriza-tions, routing restriction or restriction when utilizing special services.

A distinction is made between an analogue access, Basic Access and a PBX in relation to categories.

A category for an analogue or Basic Access is always related to a sub-scriber number. A Basic Access can have several subscriber numbers with each own category combination.

For a PBX, the category is related either to an individual number or to the group number. In the latter case the same characteristics defined by the categories are valid for all the extension numbers belonging to that group number.

The subscriber categories are analysed for each call to and from the sub-scriber.

The command for adding, changing or deleting a category is SUSCC. The parameter to indicate the category is SCL (Subscriber Class), and the cate-


03802-EN/LZM 112 20 R1 45

gories have three letter codes. All these categories are listed in the Param-eter List in submodule B14. Normally SCL=xxx-1 means that the category is inserted, and SCL=xxx-0 deletes it. Most of the categories are more detailed than just ON or OFF, though. Thus the value range of this param-eter depends on the category in question.

Example

”Alarm call” has two different values:

ALS-0 The subscriber does not have access to the service

ALS-1 The subscriber has access to the service

”Priority” has four different values:

PRI-0 Ordinary subscriber

PRI-1 Priority type 1

PRI-2 Priority type 2

PRI-3 Priority types 1 & 2

To give a subscriber a “Priority type 2”-category, the command will be:

SUSCC:SNB=snb,SCL=PRI-2;

Subscriber Switch

46 03802-EN/LZM 112 20 R1

3.4 Subscriber services

As mentioned previosly, a subscriber can be given one or more categories. A subscriber can also have access to one or more subscriber services. The difference between categories and services is not always very distinct, but a service can be defined like this:

1. A service requires more data than just the category data that can be changed by the subscriber (or by an operator).

2. Administration of the service is handled by a special block.

3. The subscriber often gets access to the service by dialling a specific number or code.

A subscriber service is always initiated with the command SUSCC, but the extra information is added or changed with special commands. These com-mands are found under their own headings in the Operational Instructions.

3.4.1 DocumentationMany, but not all, categories are stored in the SC function block, which is a part of the Traffic Control Subsystem (TCS). The rest are stored in func-tion blocks in the Subscriber Services Subsystem (SUS). The SUS blocks are optional, but some features require more than one block - composite functions - and these blocks must be used together. The subscriber usually gets access to the composite functions by dialling special codes, using the characters * and #.

To perform subscriber service changes, exchange staff mainly use the fol-lowing documents:

• Operational Instruction (OPI), where commands and procedures are given

• Command Description , with possible parameters.

• Parameter List , showing the relation between category and function block. All categories are listed, and the different values of the parame-ters are given.

Example

The subscriber no. 301000 is given the “Hot Line with time delay” - serv-ice to B-no. 301123. If the A-subscriber does not dial a number, the prede-termined B-number is automatically dialled after a few seconds.

In the OPI we find “Connection/disconnection/change of subscriber func-tions”, where the command SUSCC is indicated. The Command Descrip-tion gives the format:

SUSCC:SNB=301000,SCL=HLI-2;

The subscriber now has the category, but it is not yet a service. From the operational Instruction for “Hot Line” we get the command SUHLI.

SUHLI:SNB=301000,DIN=301123;


03802-EN/LZM 112 20 R1 47

3.5 Function Blocks in ANSAThere are many function blocks in SSS. Some of the function blocks are implemented in both hardware and software while others are implemented in software only. Here follows a list of the main function blocks for ANSA:

LI Line Interface

LI contains subscriber line functions for subscribers con-nected to a subscriber stage. The hardware of this block is the LIC.

TS Time Switch

Owns the Extension Module Time Switch (EMTS) allo-cated on the TSW board. The software of TS performs the path selection through the EMTS and it also handles the Time Switch Bus (TSB) for call set up between the LSMs.

CD Clock Distribution

CD, is responsible for the synchronization of the Time Switches (EMTS) in the LSMs as well as synchronizing the EMGs towards the Group Switch.

KR2 Keyset Code Reception

KR2 performs digit reception from subscribers, equipped with tone sending telephone sets.

RT Remote Terminal

Handles the PCM links between the RSS and the host exchange. The hardware of the block is made up of the ETB in the LSM and the ETC in the host exchange.

JT Junctor Terminal

For the Central Subscriber switch CSS or LSS, JT block handles the PCM links between the JTC and the Group Switch. It owns the Junctor Terminal Circuit.

SSTONE Subscriber Stage Tone

SSTONE performs the timing (pulses / pauses) of various tones which are sent to the subscriber, and tones used for different types of tests.

PX Private Branch exchange

The block handles the routes to and from the PABXs con-nected to the switch. The block is implemented in central software only.

SULA Subscriber Line Adaptation

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48 03802-EN/LZM 112 20 R1

SULA handles the administration of the transmission parameters for the line circuits with changeable transmis-sion parameters.

LIM Line Interface Maintenance

LIM handles traffic functions for PABX subscribers and special subscriber equipment.

EXDAE Exchange Data Device Administration in EMG

EXDAE is a command handling block for administration of partly equipped LSMs.

SEPRM (64) Special Equipment Private Meter

SEPRM (16)

SEPRM sends pulses on the subscriber line to step the pri-vate meters. It is only used, when the SEPRM-HW is located in a external magazine. SEPRM exists in two versions, one for 16 devices and the other for 64 devices per EM.


03802-EN/LZM 112 20 R1 49

3.6 Summary• A maximum of 8 subscribers can be connected to one LIB or ALB,

which gives a maximum of 128 subscribers in an LSM-ANSA.

• An EMRP controls the units in the LSM-ANSA magazine.

• The subscriber’s connection to AXE consists of both a hardware and a software part.

• Subscriber categories contain a characteristic linked to a subscriber number. The categories affect the handling of calls to and from the sub-scriber.

• A subscriber service require a subscriber category and access to the service.

Subscriber Switch

50 03802-EN/LZM 112 20 R1

03802-EN/LZM 112 20 R1 51

4. ISDN Accesses


4.1 IntroductionIn the area of telecommunications, the trend is towards digitalization and service integration. New and profitable telecommunication services can be introduced more easily into a digital network than into an analogue net-work. The ISDN network can provide services both for analogue and dig-ital (ISDN) subscribers. The main difference between analogue and ISDN subscribers is that ISDN subscribers have access to more advanced serv-ices.

For ISDN applications two different access types exists: the Basic Access (BA) and the Primary Rate Access (PRA). The Basic Access consists of two B-channels for speech or data and one D-channel (signalling channel and packet mode data transfer). The PRA consists of 30 B-channels, one D-channel and one channel for synchronisation. For normal ISDN-sub-scribers, BA is the standard interface towards the subscriber switch, whereas for ISDN-PABX, PRA is the interface which is used.

CCITT (Comite´ Consultatif International Telegraphique et Telephonique) is a part of the International Telecommunications Union (ITU) which pro-vides Recommendations and Standards for Telecommunications.CCITT has specified reference points (interfaces) for the subscriber access to the ISDN network.Figure 3.2 shows the reference points and the loca-tion.

Chapter Objectives


• Describe ISDN Access and subscriber equipment interfaces.

• Describe the ISDN Basic Access.

• Define an LSM-BA(E) by commands.

• Connect a Multiple Subscriber Number to a Digital Subscriber Line.

• Describe the ISDN Primary Rate Access.

• Define an LSM-PRA (E) by commands.

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52 03802-EN/LZM 112 20 R1

Figure 4.2Subscriber equipment and interfaces

4.1.1 Subscriber equipmentThe Terminal Equipment (TE) can consist of either ISDN equipment (TE1) or non ISDN equipment (TE2).

A Terminal Adaptor (TA) enables non-ISDN equipment to be connected to ISDN.

The subscriber line is terminated in the subscriber premises at the Network Termination (NT).

The NT may comprise of two parts:

NT1

SSS

2B+D

TA

Subscriber Premises

30B+D

U

SR

DLIC

ETP

TE2

TE1

NT2 NT1

T

TE1

TE1

LSM-BA

LSM-PRA

BA

PRA

ISDNPABX

LT

TETA

BA

DLICTerminal EquipmentTerminal AdaptorNetwork TerminationBasic Access

ETPSSSLSM-BA

Exchange Terminal PRASubscriber Switch SubsystemLine Switch Module Basic Access

Digital Line Circuit

NT

Primary Rate AccessPRA Line Switch Module Primary Rate AccessLSM-PRA

LT Line Termination R,S,T,U Reference Points

ISDN Accesses

03802-EN/LZM 112 20 R1 53

• NT1 which terminates the subscriber line.

• NT2 which is used to switch internal traffic. NT2 only exists where internal switching is required, i.e. in an ISDN Private Automatic Branch exchange (ISPABX).

4.1.2 Reference PointsReference Point R is the interface between non ISDN standard equipment (TE2) and the Terminal Adaptor (TA).

Reference Point S is the interface between the NT and the TE1 or TA.

Reference Point T is the interface between the NT1 and NT2.

Reference Point U is on the subscriber line between the NT in the sub-scriber premises and the Line Termination (LT) in the Subscriber Switch.

4.2 Basic Access The Basic Access (2 B+D) consists of a 160 kbit/s PCM system. The net bitrate is 144 kbit/s, 2*64 kbit/s for each B-channel and 16 kbit/s for the D-channel. The additional 16 kbit/s are used for synchronisation (13 kbit/s) and maintenance (3 kbit/s) purposes.

Figure 4.3Connection of a Basic Access subscriber line

The ISDN subscriber has the possibility to use a variety of Terminal Equipment at his premises. Examples of TE are: ISDN Telephone, Data Terminals, Personal Computers and FAX machines. Up to eight ISDN ter-

DLIC

DLIC

DLIC

DLIC

DLB2-U

TSW

NT1B2 B1 D

S

D B1 B2

3

2

1

0

U

D B1 B2

B2 B1 DNT1

S, UNT1D, B1, B2

DLB2-UDLICTSW

Reference pointsNetwork Termination 1Signalling and usable channels

Digital Line Board-U interfaceDigital Line CircuitTime Switch

LSM-BA

160 Kbit/s

4 wires 2 wires

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54 03802-EN/LZM 112 20 R1

minals can be connected to the network terminal (NT1) by means of the S-Bus. The bus is a 4 wire cable and the transmission on the bus is digital. There is a balance between the amount of terminals and the length of the S-Bus. For a long S-Bus, only one terminal can be connected.

A two pair twisted cable, called the Digital Subscriber Line (DSL), con-nects the NT1 to a circuit in the LSM-BA called the Digital Line Interface Circuit (DLIC). This circuit is situated on a board called DLB2-U (Digital Line Interface Board).

The DLB2-U board contains four DLIC circuits. This implies that four Basic Accesses can be connected to one DLB2-U.

4.2.1 Function units in LSM-BAThe connection of the hardware units to the Device Speech Bus (DEVSB) and the Time Switch Bus (TSB) is shown in the figure below.

Figure 4.4Hardware units in the LSM-BA.

Time Switch (TSW)

The TSW, is implemented on one board and handles 1024 time slots. Devices contained in circuit boards are connected to the TSW via DEVSB, in groups of 8, 16 or 32 devices. For example one DLB2U board handles 4 BAs, 8 B channels and 4 D-channels (total 12 channels), and will therefore require 16 time slots in the TSW.

JTC /ETB

TSW

DCL2

7

TSB

2 B+D

2 B+D 3210

DEVSB

LSM-BA

ST64IDLB2-U

0

15

2 B+D

2 B+D 3210

DLB2-U

8

JTC /ETB

PCM to GS

SLQCT

EMRPD

TSWDCL2DLB2-USLQCT

EMRPD Time SwitchDigital Line Interface ClockDigital Line BoardSubscriber Line Quality Tester

JTBETBST64I

Junctor Terminal BoardExchange Terminal BoardSignalling Terminal Interface

Extension Module Regional Processor Device

TSB Time Switch Bus DEVSB Device Speech Bus

ISDN Accesses

03802-EN/LZM 112 20 R1 55

An LSM-BA with 64 accesses requires 256 time slots. The remaining time slots are used by JTC/ETB, SLQCT, ST64I boards and the Time Switch Bus (TSB).

Digital Line Interface Clock (DCL2)

DCL2 is common to all DLB2 boards in the LSM-BA and converts the transmission rate at the U-Interface to the rate of the Device Speech Bus.

Digital Line Board for U-interface (DLB2-U)

The DLB2-U receives the information on the B and D channels and sends them on the DEVSB to the TSW. It also provides over voltage protection, supervision of bit stream, power feed to the NT and tests the access to the digital subscriber lines. Four basic accesses (2B+D) can be connected to DLB2-U and up to 16 such boards can be installed in an LSM-BA maga-zine.

Subscriber Line Quality Circuit Tester (SLQCT)

The SLQCT provides testing mechanisms for fault localisation by looping the B and D channels at the NT or the DLIC. It also carries out signal level measurements on the DSL and checks current feed to all DCLs

ETB or JTC

ETB, Exchange Terminal Board, is used if the subscriber switch is used as a Remote Subscriber Switch, RSS. This board is the interface towards the PCM line and it contains functions similar to the ones in an ordinary ETC. JTC, Junctor Terminal Circuit, is the interface towards the Group Switch if the subscriber switch is installed locally. Also these units, ETB or JTC, are connected to the EMTS. In each LSM, two ETB/JTC can be installed.

Signalling Terminal 64 Interface (ST64I)

The ST64I extracts the D channel information from the TSW (using DEVSB) and send it to the Extension Module Regional Processor Device (EMRPD) via a back plane bus. ST64I can handle 64 D channels.

Extension Module Regional Processor Device (EMRPD).

The Extension Module Regional Processor Device, called the EMRPD, is needed in the LSM when a Basic Access is connected to the exchange. Just like an ordinary EMRP, the EMRPD contains software units for the blocks that have any hardware in the BA-LSM. It also contains software for vari-ous APZ functions like operating system and fault detection of the EMRPD itself.

The software is written in the high-level languages PLEX_M, C++ and C. The EMRP-programs written in PLEX_M are converted to C.

The difference between an EMRP and an EMRPD is that the EMRPD is designed for single control of the devices. There are no EMRPD pairs. The

Subscriber Switch

56 03802-EN/LZM 112 20 R1

EMRPD is a universal processor with an open processor bus interface, so the devices are connected directly to the processor bus

An EMRPD is based on an MC68020 micro-processor. It consists of two boards: one processor board (ST20C) and an external memory unit (MEU).

4.2.2 The LSM-BA magazineThere are two types of LSM-BA magazines. One allows 32 Basic Accesses (or DSLs) to be connected to it and the other 64.

The LSM magazine for Basic Access is shown in the figure below.

Figure 4.5Hardware Magazine of LSM-BA

4.2.3 Main Function Blocks for Basic Access

Mixed LSM consept

The development of the Basic Access interfaces, as far as the standardisa-tion procedure concerns, was described first in the ITU-T recomendations and then became ETSI standards.

TSW

DC

L2

DL

B2-

U

ST20

C

DL

B2-

U

DL

B2-

U

DL

B2-

U

+5V

PO

U

±55V

PO

U

ME

U

ST64

I

JTB

/ E

TB

JTB

/ E

TB

SLQ

CT

ST

RP

TSWDCL2DLB2-USLQCTJTBETBST64I

MEUST20CSTRPPOU

Time SwitchDigital Line Interface ClockDigital Line BoardSubscriber Line Quality TesterJunctor Terminal BoardExchange Terminal Board

Memory UnitProcessor type ST20CSignalling Terminal RemotePower

Signalling Terminal Interface

TSB-A/B

EMRPB-A/B

GSS(STR)

4 DSLs

ISDN Accesses

03802-EN/LZM 112 20 R1 57

Based in the ITU-T recomendations for D-channel signalling, Ericsson developed the BA magazine, figure 3.5, and proper software blocks to operate the hardware and the services.

The main function blocks in ISDN Basic Access (ITU-T) are shown in the figure below.

Figure 4.6LSM BA function blocks

Line Interface For Basic Access, LIBA

The main task of LIBA is to handle the line interface functions for normal traffic handling and some operation and maintenance functions. This block controls the DLB2 board.

Signalling Terminal Layer 2, STL2

The main task of block STL2 is to handle D-channel layer 2 signalling which uses the Link Access for D-channel protocol (LAPD).This block controls the ST64I board.

Subscriber Line Quality Circuit Tester, SLQCT

SLQCT carries out quality and circuit tests on digital subscriber line cir-cuits (basic access). SLQCT provides access to digital subscriber lines and line circuits via the external test bus. SLQCT supervises clock and power feed functions to digital subscriber line circuit boards.

Message Handler Basic Access, MHBA

CP

EMRP

SLQCTDLB2-U

LSM

C-SW

R-SW

SSTONER

EXDAU

ST64I

MHBAR

MHBAU MANBAU

STL2R

STL2U

MANBAR

LIBAUSSTONEU

LIBAR SLQCTR

SLQCTU

Subscriber Switch

58 03802-EN/LZM 112 20 R1

MHBA performs buffering of D-channel layer 3 call control messages and perform the administration of call identities for the terminal portability function.

Management of Basic Access, MANBA

MANBA performs an analysis of D-channel layer 3 messages.

Subscriber Stage Tone, SSTONE

SSTONE’s function is the sending and distribution of tones in SSS.

Exchange Data Device Administration for EMG, EXDAE

EXDAE administrates the two functions “Partly equipped LSM” and “Allocation of Hardware Equipment Modules (HEM) in EMG.

In order to comply to ETSI standards a modification of some software blocks and addition of new took place. The BA hardware is unchanged. The BA LSMs can therefore be configured as following :

• ‘old’ BA (not ETSI complient). Access device name LIBA-x

• new BA named BAE (BA ETSI complient). Access device name LIBAE-x

• mixed LSM where both BA and BAE co-exist in the same magzine or even the same board. Access device name LIBA-x , LIBAE-y.

Below a smplified block interworking is presented. Case PSTN over BA-E.

.

Figure 4.7PSTN over BA (ISDN-E), Internal interwork diagram

DLB-U ST64I

LIBAER

PSTNHHR

STL2R

MANBAR /MANBAER

MHBAR /MHBAER

STL2U

LIBA(E)U

EXDAEU LIHHU PSTNHHU

KR2U MANBAEU MHBAE

HARDWARE

EMRPD

CP

ISDN Accesses

03802-EN/LZM 112 20 R1 59

The BA user interface is implemented in DL Board for U interface. It is controlled by the function block LIBAE as shown in the figure above. The function block LIBAE comprises subscriber line functions for subscribers connected to a subscriber switch with ISDN, 2B+D. The major functions are:

− Handling of LIBAE device state

− Blocking/Deblocking of the Access

− Layer 1 supervision and statistics

− Periodic, Routine and Command Controlled tests

− Traffic functions support

− HEM administration (participation in definition, removal and change of device allocation within DLB-U HEM’s).

− Handling of semipermanent connections

− Extended functionality for device state handling, blocking/deblocking of the access and traffic support due to PSTN over BA functionality

− Support of PSTN over BA connections administration

The HEM administration is mainly handled by the block EXDAE. It han-dles commands concerning the administration of Hardware Equipment Modules (HEM) and the association of traffic to hardware devices. The HEM administration command handling part consists of commands for allocation and removal of hardware equipment modules and change of device allocation within hardware equipment modules that can be control-led by more than one device type.

In the case of PSTN over BA connections an association of a traffic device to a hardware device is made. Block EXDAE handles this command func-tion, in cooperation with the block LIHH, Line Interface Home Highway.

In order to support the L3 protocol for PSTN over EMRPD BA connec-tions, a protocol based on the V5 PSTN protocol is realised in the block PSTNHH (PSTN Home Highway). This block participates in the function for traffic to hardware device association (PSTN over BA connections) storing static data for such connections.

The user can use the BA connection to send a wide range of information types. The interface has then to distinguish the different types and handle them properly. For instance Packet switching data has to be treated differ-ent than normal signal data. Packet switching data (SAPI=16) is frame relayed further via the time switch and the group switch towards the FH concentrator. On layer 2 the block STL2 performs the protocol function for call control procedures (SAPI=0, for both ISDN and PSTN over ISDN-E BA) and some Layer 2 management procedures (SAPI=63) on the D-channel.

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60 03802-EN/LZM 112 20 R1

The management of the Basic Access is handled by the ‘old’ block MANBA, (MANagement of Basic Access). MANBA handles manage-ment of terminal endpoint identification, Layer 2/Layer 3 interwork and Layer 3 supervision and statistics (only for ISDN). ISDN layer 3 protocols supported are DSS1 and QSIG (the latter only in MANBA(BA-E)).

Moreover, block MANBAE supports a multiprotocol mechanism enabling the support of more than one protocol/protocol variants in the same exchange on a per access basis, as well as of protocol market options.

Finally, it takes part in the handling of permanently activated data links for PSTN over BA (Layer 2/Layer 3 interwork).

The DSS1 signalling messages coming from the user has to be buffered and analysed. The block Message Handler Basic Access (MHBA) imple-ments these functions. It also builds Layer 3 messages in the network to user direction. In addition, MHBA(BA-E) buffers and analyses the Layer 3 QSIG protocol format, dummy calls and segmented or not messages to/from the user.

4.2.4 Definition of an LSM-BAAfter installing the LSM- BA and connecting the hardware, the LSM- BA should be defined in the exchange data.The documentation to be used is found in the B module. The Operational Instructions “Addition of LSM in an EMG“ and “Connection of Interface Equipment for ISDN Basic Access in LSM” should be followed carefully.

In the text below the procedure for definition of an LSM-BA is described.

• EMRPD definition

EXEPI:EMG=LSS0, EM=2,TYPE=EMRPD1;

• Loading of regional software units and equipment into EMRPD

EXEUI:EMG=LSS0, EM=2, SUID="................"; ! LIBAER !

EXEUI:EMG=LSS0, EM=2, SUID="-------------"; ! MHBAR !

EXEUI:EMG=LSS0, EM=2, SUID="-------------"; ! MHBAER !

EXEUI:EMG=LSS0, EM=2, SUID="-------------"; ! PSTNHHR !

EXEUI:EMG=LSS0, EM=2, SUID="-------------"; ! FHLR !

. . .

. . .

EXEEI:EMG=LSS0, EM=2, EQM=LIBAE;

EXEEI:EMG=LSS0, EM=2, EQM=MHBA;

EXEEI:EMG=LSS0, EM=2, EQM=MHBAE;

EXEEI:EMG=LSS0, EM=2, EQM=FHL-1;

ISDN Accesses

03802-EN/LZM 112 20 R1 61

. . .

. . .

As shown in the commands above, for some of the software units both the blocks for the BA and BAE are loaded. The devices then, can be, for example, LIBA or LIBAE. By initiating and change the HEM parameters, one can chose the type that is currently needed.

The hardware equipment module (HEM) has to be specified and given the name belonging to the proper hardware owning block. In the case the hard-ware is the DLB2U the HEM name is specified in the owning block LIBAE. The LIBAE devices has then, by the command, to be allocated to the defined HEM.

EXHMI:EMG=LSS0, EM=2, HEM=DLB2U-0, TMAG=LSM32, DEV=LIBAE-64&&-67;

EXHMI:EMG=emg,EM=em,HEM=SLQCT-0;

EXHMI:EMG=emg,EM=em,HEM=ST64I-0;

EMG Name of extension module group EM Number of extension module HEM Hardware equipment modules TMAG Magazine type DEV Devices

Equipment in the EMG LSS0 is defined by specifying the hardware equip-ment modules associated with a previously defined Extension Module (EM) 2. Parameter TMAG must is given to define HEMs for blocks that can handle different types of magazines. The devices LIBAE-64&&-67 are connected to the specified HEM.

EXHMC:EMG=LSS0, EM=2, HEM=DLB2U-0, DEV1=LIBAE-64, DEV2=LIBA-0;

After this command the LIBAE-64 is replaced by the LIBA-0. By using the EXHMC command, the LIBA devices can be connected to the speci-fied HEM.

4.2.5 Connection of subscriber for BAFor subscribers connected to the analogue devices only one subscriber number can be connected to a subscriber line. With the introduction of ISDN it is possible to connect several subscriber numbers to a single sub-scriber line for Basic Access. The OPI “Connection of subscriber line” should be used.

Example:

SULII:SNB=221170&&221177,DEV=LIBA-0,ONELINE;

SNB Subscriber numbers

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62 03802-EN/LZM 112 20 R1

DEV Device ONELINE Allows connection of several subscriber numbers to one

subscriber line

Change of subscriber categories

In the example below, the subscriber number is given the subscriber cate-gory Multiple Subscriber Number.

SUSCC:SNB=221170,SCL=MSN-1;

SNB Subscriber number SCL Subscriber class

For each subscriber number, allocation of subscriber class is needed.

Modification of access parameters

SUAPC:DEV=dev,APA=apa;

DEV device APA access parameters

4.2.6 BA-E Subscriber connectionThe ISDN-E Basic Access offers a wide range of functions and although it is used as the standard BA, the ‘old’ BA access is still functioning.

In the BAE case, the subscriber numbers can not be connected as above. The following commands have to be used:

IUDCI:DEV=LIBAE-76, SNB=70002012&&70002015;

IUDCI:DEV=LIBAE-80, SNB=70002416&70002418&70002419, ONELINE;

This command connects one or more subscriber numbers to one or more devices. After connection, a default set of basic services, supplementary services, and properties are automatically assigned to the device or sub-scriber number. If several subscriber numbers are specified in the com-mand, and parameter ONELINE is not given, each of the subscriber numbers is connected to its own device. The first subscriber number is connected to the device given in the command, the second subscriber number is connected to the device plus one, and so on.

The first subscriber number connected to the device is known as the Default Calling Number (DCN).

In applications that support multiple access protocols, the user can specify the protocol variant to be used for the access. Only one protocol variant is allowed per access. If the relevant parameter is omitted and the access is not connected, the default protocol variant, DSS1E, is given to the access.

Access related A-number validation

ISDN Accesses

03802-EN/LZM 112 20 R1 63

The local exchange checks whether the transmitted A-number is among those, allocated to the access, and guarantees that the A-number transmit-ted to the B-subscriber identifies the calling party correctly.

• Activation of A-number validation

IUANI:DEV=LIBAE-80, SNB=70002416&70002418&70002419, BCH=ALL;

A-number validation is activated for the Basic Access LIBAE-80. The indicated numbers are those that are expected from the ISDN-terminal as A-numbers. If the local exchange recognises one of these numbers, the validation will be successful and the numbers are sent to the B-subscriber. Otherwise the access default number (DCN) will be sent to the B-sub-scriber.

Connection of line hunting group with ISDN-E subscribers, BALine hunting group is a call distribution mechanism using a group number that contains several BA. The hunting group is applied normally in cases that PBX function is used. No direct dialling is used and the already known hunting methods are applicable.

In applications that support Multiple Access Protocols, the operator can specify the protocol variant to be used for all accesses connected to the PBX.

Commands, parameters, values

• Connection of line group hunting number

IUPBI:PBX=COMPANY12, SNB=70002560,REFP=1;

Group number is connected and a set of default services for point-to-multipoint configuration is available.

• Connection of line group devices

IUPDI:PBX=COMPANY12, DEV=LIBAE-88&-89;

Basic accesses are connected to the group number

• Connection of several vacant subscriber numbers to PBX.

IUPNI:PBX=COMPANY12, SNB=70002561&&70002569;

The PBX must have previously been defined using the command IUPBI. A subscriber connected to a PBX is called a Group number related Indi-vidual Number, GIN.

Similar to the A- number validation for a normal BA-E subscriber, the PBX number validation has to be defined:

Subscriber Switch

64 03802-EN/LZM 112 20 R1

IUPVI:PBX=COMPANY12, DEV=LIBAE-88, SNB=70002561&&70002569, BCH=ALL;

Hunt groups are groups of B-channels connected to a specific PBX. They are used in the search (hunt) for a free B-channel when a call connection request exists. The hunting type connected to the PBX defines the search order of each hunt group when a terminating call reaches the PBX.

• Definition of line hunt group

IUPHI:PBX=COMPANY12, HG=12, DEV=LIBAE-88, BCH=ALL,HNB=0;

Each PBX has hunt groups connected to it, and each hunt group has basic services, a hunting type, and sometimes reduced hunting connected to it. These parameters are originally set up using an exchange parameter and can later be changed using the command IUPHC.

• Definition of line hunt group characteristics

IUPHC:PBX=COMPANY12, HG=12, HT=1;

Hunting type 1 means cyclic hunting. The selection process will start from the B-channel after the one which was seized from the previous call.

• Adaptation of Access parameters (point-to-multipoint)

The access characteristics, defined as access parameters, can be modified by the following command.

IUAPC:DEV=LIBAE-80, APA1=OOA-1;

Here, the access on LIBAE-80 receives the Access Parameter OOA-1 (Origin for Output Analysis). 1 is the origin for output analysis when retrieving cause or other output information or both. The block LIADM handles the access parameters.

The PBX configuration above is by default a Point-to-Point configuration. This means that Layer 2 will be established with a fixed TEI-value, that can’t be accepted by the ISDN-terminals (they only accept TEI-127 (broadcast)). Note that the parameter REFP of command IUPBI has noth-ing to do with Layer 2; it’s only used to define the services, that shall be available for the connected subscribers. Therefore an adaptation has to be done so that AXE starts call set up with TEI-127.

Layer 2 call set up will be initiated with TEI-value 127 (broadcast). Each connected ISDN-terminal will accept this call.

PSTN over ISDN BA

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03802-EN/LZM 112 20 R1 65

The block LIHH, as device owner for the PSTN part of the access, PSTN over ISDN-BA, handles the following administration functions.

− Connection/disconnection of PSTN traffic device to ISDN hardware device

− Connection/disconnection of subscriber number to PSTN traf-fic device

− Blocking/deblocking of PSTN traffic device

− Maintenance functions i.e. Fault handling, L2 data link status.

If a PSTN over BA shall be defined, in addition to the EM and HEM defi-nition the association of the traffic devices LIHH to the LIBAE devices has to be given. Since the TEI value is important for the signalling, the traffic device has to be connected to it. This is implemented by the com-mand:

EXTHI:DEV1=LIBAE-1,DEV2=LIHH-3,TEI=126;

Traffic device LIHH-3 is connected to HW device LIBAE-1. TEI value 126 is allocated to the traffic device.

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4.3 ISDN Primary Rate Access, PRA

Figure 4.8ISDN Primary Rate Access

Primary Rate Access terminates a 2 Mbit/s PCM which connects an ISDN-PABX to the subscriber switch. PRA offers 30 B-channels and one D-channel. The remaining channel is used for synchronization. ISDN termi-nals can be connected to the ISDN-PABX by means of the S interface Bus.

The interfaces and connection of a PRA is shown in the figure above.

The D-channel uses a layered protocol according to ETSI or to ITU-T called Digital Subscriber Signalling System Number 1 (DSS1) .

The ITU-T PRA (denoted PRA) is not implemented in AM adapted AXE while the ETSI PRA (denoted PRAE) is. PRA functions inter-work with both AM and not AM adapted environment supporting ISDN and ISDN-E subscribers respectively.

The PRA access is partly implemented in the PRA Set of Parts in the sub-system SSS, and partly in the system module DASAM. DASAM is

TA

Subscriber Premises

30B+D

U

SR

TE2

TE1

NT2 NT1

T

LSM-PRA

PRA

ISDNPABX

ETP

4 PRA/LSM

DIP

2Mbit/s

TETA

DIP

LSMTerminal EquipementTerminal AdaptorNetwork TerminationDigital Path

ETPR,S,T,ULSM-PRA

Exchange Terminal PRARefrence PointsLine Switch Module Primary Rate Access

Line Switch Module

NT

Primary Rate AccessPRA

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03802-EN/LZM 112 20 R1 67

responsible for the connection and disconnection of ISDN E subscribers and PBXs and for a number of access related supplementary services, for example, Line and Trunk Hunting and Terminal Portability. DASAM also includes functions for data recording and monitoring of subscriber lines.

The lower level functions of ISDN, Layer 1 (the physical layer), Layer 2 (the data link layer) and the message handling of Layer 3 (network layer) are located in the Digital Subscriber Access (DSA) service implemented in XSS. The controlling software is located in DASAM. This allows for a separation of the technology from the application.

The connection in the SSS is made on the Exchange Terminal for primary access and at the users premises in terminal equipement (PBX or IMUX) with NT2 functionality

4.3.1 Function Units in LSM-PRAA 2Mbit/s PCM from an ISDN-PABX is connected to the Exchange Ter-minal for primary access, board (ETP) in the LSM-PRA. Up to four ETPs can be installed in one LSM-PRA which implies that four PRAs can be connected to one LSM-PRA.

The same hardware is used to offer user connections for:

• PRA. The device type is then LIPRA

• PRAE. The device type is then LIPRAE

• Mixed PRA and PRAE .The device type is then LIPRA and/or LIPRAE

• V5 inteface mixed (V5.1 / V5.2SL). The device type is then LIANV5

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Figure 4.9LSM PRA Structure

Since ETP is the interface to the PCM link, Digital Path (DIP) operation and maintenance functions are included in the ETP. An example of a maintenance function is transmission quality supervision on the PCM.

The ETP also separates the D- Channel from the B-channels and connects the D-channel to an access device. Both the D-and the B- channels are sent to TSW via the Device Speech Bus (DEVSB) and further to GS if the call is not intra-EMG call. The ETP forms a Switching Network Terminal (SNT) function which has to be connected to the TSW.

The D-channel transfers mostly signalling information that has to be send to CP, therefore, a communication platform between the PRA or PRAE access and the CP via GS has to be introduced. This platform is called Generic Access Management, GAM.

PRADIP

LSM-PRAPrimary Rate AccessDigital PathExchange Terminal PRA JTC

TSWJunctor Circuit CircuitTime Switch

Line Switch Module Primary Rate Access

ETPExchange Terminal BoardETB

Switching Network TerminalSNT TSB Time Switch BusDevice Speech BusDEVSB EMRP Extension Module Regional Processor

STD

STDSTD

JTC /ETB

TSWTSB

DEVSB

ETCP

JTC /ETB

PCM to GS

EMRP

4 PRADIP

SNT

LSM-PRA

30B+D

30B-ch

RPG

RPB

To CP

D-ch

GAM

GAM Generic Access Management

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03802-EN/LZM 112 20 R1 69

4.3.2 The LSM-PRA magazine As mentioned earlier, the LSM-PRA consists of four ETPs and four STDs, allowing up to four PCM links to be connected to one magazine. If one or two connections to the Group Switch are required, then up to two ETB/JTC can be installed.

The EMPC-board is the EMRP processor (EMRP3) for the LSM-PRA.

Figure 4.10The LSM-PRA magazine

TSW

ETCP

ETCP

ETCP

ETCP

ETB

ETB

EMPC

POU

2 Mbits/s PCMs 30 B +D each

TSW

ETB

Time SwitchExchange Terminal PRAExchange Terminal Board

ETPSTRP

POU

Signalling Terminal RemoteExtension Module ProcessorPower Unit

EMPC

STRP

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70 03802-EN/LZM 112 20 R1

4.3.3 Function blocks for PRAThe main functions for PRA are handled by a number of function units.

Figure 4.11Function blocks for Mixed LSM PRA

The internal interfaces within the Primary Rate Access are shown in the figure above. This interwork applies for accesses connected through the Generic Access Manager, LSM connected.

The function blocks implementing the PRA differs depending on if PRA and PRA-E are supported. Some of them are described below.

ETGAM, ETGAM, Exchange Terminal, Generic Access Manager, Mixed LSM.ETGAM is the maintenance and EM han-dling block for the ET hardware using ISDN common channel signalling. It supervises and maintains the Layer 1 and reports possible faults to the owner of the inferior entities (DIPST, which owns the DIP and the Line Inter-face block, responsible for the devices).

ETGAM performs test in order to discover possible faults in the ET hardware and takes actions to recover from the faults. The Mixed LSM ETGAM also supports the option to mix different types of GAM accesses within the same LSM magazine. This ET block is designed to manage the ETs connected to the TS in the RSS structure. Each ET is seen by the operators as an SNT. Each ET can handle up to 31 time slots. Each time slot can either be used as B-channel or a signalling channel.

TRHB/RPGETP30B+DHW

EMRP STGAMR

G A M

GAMCONUGAMCORDUGAMADMU

STGAMU

CP

RPD/RPG

GSN

ETGAMR

ETGAMU

DLPRAR

MANPRAR

MHPRAR

MHPRAU

MANPRAU

DLPRAU

DIPSTU DIPSECU

LIPRAU

LIPRAR

JTC /ETB-ETC

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03802-EN/LZM 112 20 R1 71

For the GS connected PRA the ETGAMU handles the maintenance of the ETC hardware and the maintenance of the digital line.

ET consists of central software, regional software and the printed board ETC (Exchange Terminal Circuit).

DIPST, Digital Path supervision and test for GAM. The block contains functions for DIP administration, DIP mainte-nance, HW maintenance and Clock reference administra-tion for those accesses connected through the Generic Access Manager (GAM).

LIPRA, (E) Line Interface for Primary Rate Access connected via GAM The function block LIPRA contains functions for handling of traffic devices for Primary Rate Accesses connected to the AXE through the Generic Access Man-ager (GAM). Its main functions are handling of the B-channels for traffic and storing of subscriber data related to the PRA. It interworks with the Generic Access Man-ager (GAM) requesting the connection and the deletion of internal signalling paths and being informed in case of faults affecting such paths or in case of switch-overs.

There are three versions of the block: one for non AM adapted LSM connected PRA, one for AM adapted LSM connected PRA (LIPRAE) and one for AM adapted GS connected PRA.

LIPRAE interworks with AM-user which controls traffic on PRA devices. LIPRAE controls the administration of these devices. LIPRAE plays a key role in management of internal signalling path connections for the General Access Manager platform.

LIPRA(E) also accommodates the optional Frame Han-dler. As already mentioned in the relevant chapter, the Frame Handler is an integral part of the ISDN service, also located in the SSS subsystem. It is required to pro-vide Primary Rate Accesses and Basic Rate Accesses a D-channel access to the X.31 Case B Packet Mode service. LIPRA is involved in the initiation and termination of supervision and statistical functions on L2 and L3.

DLPRA, (E) Data Link Layer handler for Primary Rate Access. DLPRA performs the Layer 2 protocol function for call control procedures (SAPI=0) and some Layer 2 manage-ment procedures (SAPI=63), on the D-channel. Packet switching data (SAPI=16) is frame relayed further via the group switch towards the FH Concentrator.

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The Frame Handler Local (FH-L) function is imple-mented in DLPRA. The FH-L function separates SAPI=16 and SAPI=0 frames from the D-channels and concentrates the SAPI=16 frames into one or more IBD-channels. An IBD-channel is an internal BD-channel for packet data between FH-L and FH-C.

It also maintains the statistics and supervision function of the D-channel at Layer 2. It is used for the Primary Rate Accesses connected through the Generic Access Manager (GAM).There are two versions of the block: one working with the AM adapted (DLPRAE), LSM or GS connected PRA and the other one for non AM adaptation.

DLPRA maintains the statistics and supervision function of the D-channel at Layer 2.

MANPRA,(E) MANagement of Primary Rate Access The function block MANPRA is used in the Primary Rate Access connected through the Generic Access Manager (GAM). MANPRA handles Layer 2/Layer 3 interwork and Layer 3 supervi-sion and statistics.There are two versions of the block: one working with the AM adapted, LSM or GS connected PRA and the other one for non AM adaptation.

Block MANPRA(E) contains functions for:

• Management of a primary rate access

• Layer 2 link management

• Layer 3 statistics and supervision

• Detection of abnormalities

• Coordination and reporting of layer 3 statistics per access

• Handling multi access protocols

MANPRA is placed between the layer 2 protocol handler, DLPRA and the layer 3 message handler MHPRA.

MHPRA (E), Message Handler for Primary Rate Access connected via GAM The function block MHPRA performs buffering and analysis of DSS1 Layer 3 messages from the user.In the outgoing direction, MHPRA performs the building of Layer 3 messages to the user.

The block MHPRA(PRA-GAM-E) performs buffering and analysis of Layer 3, included QSIG protocol format, dummy calls and segmented or not messages from/to the user. It is used for those Primary Rate Accesses con-nected to the exchange through the Generic Access Man-ager (GAM). There are two versions of the block: one

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03802-EN/LZM 112 20 R1 73

working with the AM adapted, LSM or GS connected PRA and the other one for non AM adaptation.

DIPDIG, Digital Path supervision and test for DPNSS sIGnalling access DIPST contains functions for fault and quality supervision, test etc of DIPs connecting RSS to GSS and SSS to NT. DIPST receives and collects information of DIP transmission status from ET and RT. DIPST is imple-mented in central software only.

LIDIG, Line Interface DPNSS sIGnalling access. Handles the Layer 3 and Layer 2 DPNSS signalling protocol and effects traffic line signalling accordingly. The Layer 2 protocol messages are supervised and presented to the ACAM which has the Layer 3 traffic functionality. Func-tion block LIDIG (a Line Interface type block) provides an access for DPNSS1 PBX’s to allow connection to BCAM VPN. LIDIG allows connection and disconnec-tion of AM (Application Modularity) DPNSS1 PBX sub-scribers to enable calls to and from the DPNSS1 PBX’s to be processed by the AM. However LIDIG’s involvement in call control is minimal since the protocol is handled by the Access-AM function block PCDPNSS.

LIDIG is part of the Subscriber Switching Subsystem (SSS).

4.3.4 Connection of an LSM-PRAFor addition of an LSM-PRA in an existing EMG, Operational Instruction “Addition of an LSM in EMG” should be used. This OPI will lead to another OPI called “Connection of interface equipment for ISDN Pri-mary Rate Access”.

In the text below the procedure for definition of an LSM-PRA is described.

As mentioned above, PRA implemented in XSS (GAM based) and the PRA in DASAM (GAM, ISDN E) can exist in the same application. In the procedure below, a PRA definition is made for a mixed LSM. It means that both PRA and PRAE are defined in the same LSM.

The GAM application on RPD (or RPG) for the PRA and PRAE is not implemented in the same regional software units (R-Sw). Both the proce-dures are presented below:

Connection of signalling terminal for GAM

• Definition of the RPD used for the GAM. An RPG, used for GAM application, is defined in the same way.

EXRPI:RP=rp,RPT=rpt,TYPE=RPD1A;

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74 03802-EN/LZM 112 20 R1

• GAM definition for PRA ISDN non-ETSI adapted

EXRUI:RP=76, SUID="xxxxxxxxxx"; ! STGAMR !

EXRUI:RP=76, SUID="yyyyyyyyyy"; ! DLPRAR !

EXRUI:RP=76, SUID="zzzzzzzzzzzzz"; ! MANPRAR !

EXRUI:RP=76, SUID="vvvvvvvvvv"; ! MHPRAR !

• GAM definition for NEW PRA ISDN-E !

EXRUI:RP=77, SUID="--------------"; ! STPRAER !

EXRUI:RP=77, SUID=" ................."; ! DLPRAER !

EXRUI:RP=77, SUID=",,,,,,,,,,,,,,,,,"; ! MANPRAER !

EXRUI:RP=77, SUID="++++++++"; ! MHPRAER !

All SW units, which are needed to control the signalling terminal are defined, i.e. handling of Layer 2 and Layer 3 protocol. The handling of the SNT administration and maintenance of TRHB board used as signalling terminal in the GAM platform, is implemented in the unit STGAMR and STPRAER for ISDN respectively ISDN-E. A short function description of the R-Sw units follows:

STGAMR

The regional RPD block STGAMR orders tests of the TRHB board and supervises the signalling links by sending test frames at regular intervals. It performs the SNT administration and maintenance. If a fault is detected either on the TRHB board or on the signalling links, the fault is reported to STGAMU.

DLPRAR, DLPRAER

The Frame Handler Local (FH-L) function is implemented in DLPRA. The FH-L function separates SAPI=16 and SAPI=0 frames from the D-channels and concentrates the SAPI=16 frames into one or more IBD-channels. An IBD-channel is an internal BD-channel for packet data between FH-L and FH-C.

MANPRAR, MANPRAER

Function block MANPRA(E)R reports Layer 3 abnormalities to block MANPRA and colects data for supervision and statistics purposes.

MHPRAR, MHPRAER

This function block, in cooperation with the MHPRA performs the buffering and the analysis of layer 3 messages coming from the user and the building of layer 3 messages in the network to user direction.

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03802-EN/LZM 112 20 R1 75

• The equipment for the R-SW units above has then to be defined

EXEMI:RP=rp,RPT=rpt,EM=em,EQM=STGAM-0; and so on.

• The TRHB (TRansceiver Handler Board) is physically connected to the group switch via a DL2 line. It realizes then an SNT defined as follow-ing.

NTCOI:SNT=STGAM-0, SNTP=sntp, SNTV=x; ! RPD !

NTCOI:SNT=STPRAE-0, SNTP=sntp, SNTV=y;! RPD !

SNT TRHB board used as signalling terminal in RPD SNTV HW variant of the THRB board SNTP Connection point to GS

• Definition of device numbers controlled by TRHB.

EXDUI:DEV=STGAM-0&&-31; ! RPD or RPG!

EXDUI:DEV=STPRAE-0&&-31; ! RPD !

DEV Device numbers controlled by TRHB-0 board

Connection of Primary Rate Access in Mixed LSM

Figure 4.12Commands for PRA definition (simplified)

RPD-YRPD-X

CP-A CP-B

TRH

ETCP30 JTC

EMTS

EMRP

GSS

DTDIINTCOI

EXEEI

EXEUI / EXEDP

LSM PRA

EXDUINTCOI

EXEMI / EXEMPEXRUI / EXRUPEXRPI / EXRPP

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76 03802-EN/LZM 112 20 R1

• Definition of EMRP SW in Mixed PRA LSM units (assumption: CSS)

EXEUI:EMG=LSS0, EM=5, SUNAME=ETGAMNR;

EXEUI:EMG=LSS0, EM=5, SUNAME=LIPRAR;

EXEUI:EMG=LSS0, EM=5, SUNAME=LIPRAER;

and so on..

The remaining blocks (TSR, CDR, SSTONER and JTR) are used for standard tasks within LSM.

• Following the definition of Primary Rate Access equipment per EM has to be performed.

EXEEI:EMG=LSS0, EM=5, EQM=ETGAM-4&&-7;

EXEEI:EMG=LSS0, EM=5, EQM=LIPRAE-0&&-127;

EXEEI:EMG=LSS0, EM=5, EQM=LIPRA-256&&-383;

and so on...

• A PRA access connects to ETP board, which has to be defined as an SNT for the Access signalling.

NTCOI:SNT=ETGAM-4, SNTV=2;




As seen in the EXEEI, four LIPRA ETPs are defined (128 devices). In the same LSM (EM=5) four LIPRAE ETPs are defined as well. There is no PRA LSM with eight ETPs, this is the Mixed LSM concept. One of the accesses, PRA or PRAE can be the owner of an access (SNT).

• The commands below assign owners to each access

GNSAI:SNT=ETGAM-4, ACCOWN=PRAE;



GNSAI:SNT=ETGAM-7, ACCOWN=PRAX;

So, the SNTs ETGAM-4 to 6 are owned by the PRAE and the ETGAM-7 by PRAX (PRA in XSS)

• Following the access DIPs has to be connected. In this example, the ETGAM-6 SNT is serving BGC connections

DTDII:DIP=4ETGAM, SNT=ETGAM-4;


DTDII:DIP=6ETGAM, SNT=ETGAM-6; ! BGC !

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03802-EN/LZM 112 20 R1 77


The cyclic redundancy check, CRC, parameter specifies the Layer 1 trans-mision algorithm. The Access Unit (for example IMUX or IPBX) has to be configurated to use the same CRC algorithm. CRC=0 means that only Frame Alignment Signal word violations are counted as bitfaults.

DTIDC:DIP=4ETGAM, CRC=0; and so on...

The Bit Fault Frequency ( parameter BFF), the Sleep Frequency (SF) and the Disturbance frequency values, are used as alarm triggers. When the lower limit is reached an alarm is generated. The command used is pre-sented for the 4ETGAM and has to be given for the other DIPs as well:

DTQSC:DIP=4ETGAM, BFF, BFFL1=100, ACL1=A3, BFFL2=800, ACL2=A2;

DTQSC:DIP=4ETGAM, SF, SFL=5, ACL=A3, TI=24;

DTQSC:DIP=4ETGAM, DF, DFL=5000, ACL=A3, TI=24;

When the limits are set, the command DTQSI has to be used to enable alarm printouts for the specified quality supervision on the specified dig-ital paths. The alarm classes can be modified by using the commands DTFSC and DTFSI.

As described in the chapter handling the GAM, the concept has been intro-duced to offer a flexible and simple handling of the signalling on the 2 Mbit/s interfaces of different types. The PRA (E) signalling channels are connected to GAM application on RPD or RPG. The signalling channels of the same type of generic access can be connected to the same Access Group. The Access Group (AG), is then, a group of accesses of the same type (Primary Rate Access for example) whose signalling channels are connected to the same signalling terminal and whose Layer 2 and Layer 3 protocol is handled in the same way in the RPD.

Each AG has a number, which is the access group reference. The AG ref-erence is a logical number that refers to the AG and not to any physical hardware.

The connection between the AG reference and a physical signalling termi-nal is handled automatically by GAM. For each application (PRA, V5 etc.) there is a pool of signalling terminals, from where GAM fetches a signal-ling terminal to connect it to an AG in order to handle traffic.

Signalling terminals left in the pool are stand by terminals which can be connected at failure. A switch over from a faulty to a stand by signalling terminal in the same pool is done automatically by the system when a fault occurs.

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78 03802-EN/LZM 112 20 R1

The system simply has to change the connection between the AG refer-ence and the physical hardware.

The command GNACI is used to connect an AG to the Access signalling device and on the same operation to tie the access group to a specific RP type.

The RP type needs only be specified when connecting a signalling chan-nel to an access group for the first time. All subsequent signalling channels which are connected to that access group will take the same RP type. It is possible to connect up to 31 signalling channel devices to the same access group in one command. The connection relevant to our example is given below:

GNACI:AG=2, DEV=LIPRAE-16; ! ISDN-E !

GNACI:AG=2, DEV=LIPRAE-48; ! ISDN-E !

GNACI:AG=2, DEV=LIPRAE-80; ! BGC !

GNACI:AG=3, DEV=LIPRA-272; ! ISDN-XSS !

In the last step the SNT and the DIP must be deblocked.

4.3.5 Connection of a PRA Subscribers

1. Connection of group number.

SUPRI:SNB=snb,PXR=pxr,DETY=LIBA;

SNB Group number.

PXR Subroute

2. Connection of PBX line.

SUPLI:SNB=snb,PXR=pxr,DEV=dev;

SNB Group number.

PXR Subroute

DEV Device

3. Change of subscriber categories

SUSCC:SNB=snb,SCL=scl;

SNB Group number.

SCL Subscriber category

4. Modification of access parameters.

SUAPC:DEV=dev,APA=apa;

SNB Group number.

APA Access parameters

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03802-EN/LZM 112 20 R1 79

4.3.6PRA (E) - Connection of users

ExampleThe following procedure handles a PBX Subscriber Connection (Access Type PRA -E). A PBX named COMPANY5 is defined and group number 71900000 is connected to it. It is assigned the DSS1E protocol variant.

Devices LIPRAE-3, LIPRAE-4 and LIPRAE-5 are connected to the PBX named COMPANY5.

Individual subscriber numbers 71900001, 71900002, 71900003 and 71900004 are then connected to the PBX named COMPANY5. The com-mand sequency is the following:

IUPBI:PBX=COMPANY5,SNB=71900000,REFP=2, PROTVAR=DSS1E;

Command IUPBI defines a PBX, an associated group number, and a refer-ence point for the subscriber services. The reference point (T or S) is cho-sen according to the configuration of the devices to be connected.

In applications that support multiple access protocols, the user can specify the protocol variant that is to be used for all accesses connected to the PBX. If the PROTVAR parameter is omitted the default protocol variant (application dependent), is given to the PBX. Only one such command can be given at a time.

IUPDI:PBX=COMPANY5,DEV=LIPRAE-3&&-5;

Command IUPDI connects one or several devices to a defined PBX. The devices must be hardware connected. The PBX must be previously defined and connected to a group number. In applications that support multiple access protocols, all devices connected to the PBX are given the same pro-tocol variant as the PBX. If the device has an assigned protocol variant, it must be equal to the protocol variant of the PBX.

IUPNI:PBX=COMPANY5,SNB=71900001&&71900004;

Command IUPNI connects one or several vacant subscriber numbers to a PBX.

Finally, the hunting group must be specified by using the command IUPHI. Hunt groups are groups of B-channels connected to a specific PBX. They are used when the PBX receives a call (terminating call case) to search (hunt) for a free B-channel.

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The hunting type connected to the PBX defines the search order of each hunt group when a terminating call reaches the PBX.

Each PBX has hunt groups connected to it, and each hunt group has basic services, a hunting type, and sometimes reduced hunting connected to it. These parameters are originally set up using an exchange parameter and can later be changed using the command IUPHC .

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03802-EN/LZM 112 20 R1 81

4.4 Summary• For ISDN applications two different types exists: the Basic Access

(2B+D) and the Primary Rate Access(30B+D).

• CCITT has specified standard reference points for the subscriber access to the ISDN network.

• The ISDN subscriber has the possibility to use a variety of Terminal Equipment, e.g. ISDN telephone, data terminals, personal computers and fax machines.

• Up to eight ISDN terminals can be connected to the S-bus in one BA.

• An EMRPD controls the equipment in an LSM-BA.

• A maximum of 32 Basic Accesses can be connected to one LSM-BA.

• An EMRP controls the equipment in an LSM-PRA.

• A maximum of four Primary Rate Accesses can be connected to the LSM-PRA.

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EN/LZT 101 1618 R1A© Ericsson Telecom AB

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