DX MSS Architecture_doc

MSS, GCS, and CDS Architecture

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© 2011 Nokia Siemens Networks 1

Content

1 Objectives 3

2 Introduction 5

2.1 MSC Server (MSS) 7

2.2 Gateway Control Server (GCS) 9

2.3 Circuit Switched Data Server (CDS) 10

3 Cabinet Types 13

3.1 MSS & GCS Cabinet Types 14

3.2 Integrated MSC (MSCi) Cabinet Types 16

3.3 CDS Cabinet Type 17

4 Functional Units 19

4.1 Ethernet-based Message Bus (EMB) 20

4.2 14A Cabinet (14AC) 22

4.3 14B Cabinet (14BC) 35

4.4 14C Cabinet (14CC) 37

4.5 CDS in standalone mode 42

5 Redundancy 45

6 Capacity in M14 46

7 Glossary 47



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1 Objectives

After completing this module, the student should be able to:

Mention connectivity of Network Elements in Release 4

List the main functions of the MSS, GCS and CDS

Explain the main functions of each functional unit

List the redundancy principles for the units in MSS, GCS and CDS

Explain the main difference between the standalone MSS and integrated MSS


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2 Introduction


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In Release 4 configuration, Network Element (NE) installed in the area of Switching Core Network (SCN) consists of two platforms which are DX200 and IPA2800. Following figure shows how the whole NEs in SCN are connected one and another.

All MSC Server products are based on DX 200 hardware, which uses Intel Pentium processors. The Integrated MSC Server is a feature in the MSCi. Thus the HW configuration is similar to the MSCi as well. This ensures an easy and cost-efficient upgrade for the existing MSCi elements to Integrated MSC Servers. The standalone MSC Server is based on the DX 200 Server Platform. DX 200 Server Platform is a new HW configuration optimized for call control. It is a pure server configuration that utilizes double computer cartridges. This minimizes the floor space requirement and maximizes performance. However, all plugs in units are the same as in the DX 200 MSCi, so it also offers full synergy with other DX 200 elements.

Exact specifications for the interfaces between the modules make it possible to add new functions without changing the system architecture and enable the system’s remaining up-to-date throughout its long operational life.

The possibility to build different network elements, which provide different functionalities, is a good example of the versatility of the HW architecture.

Network Elements in Rel 4

Fig. 1 Overview of the GSM/UMTS network in Release 4


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2.1 MSC Server (MSS)

The MSS is a compact standalone server product that offers processing power that is needed when one server controls several MGWs.

Basically the MSS does not have Group Switch for switching 64 Kbit/s TDM channels but an optional small GSW can be included in the configuration if required for TDM based SS7 signaling.

There are two types of MSS:

Standalone MSS

Integrated MSS

2.1.1 Standalone MSS

The figure below presents the block diagram of the MSC Server at system level M14.

Hardware architecture for Standalone MSS

Fig. 2 Hardware architecture for standalone MSS

The new hardware introduced in M14 is summarized as below:

Ethernet Message Bus (EMB)

ESB14-A

GSWB2k

ET16 and ETS2

New Mass Memory- Blu-Ray DVD


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2.1.2 Integrated MSS

As a regular MSC can be upgraded to the Integrated MSS it can be seen that block diagram of Integrated MSS includes all the functional units available also in a regular MSC. Naturally here the GSW is included since this network element can also handle user and control plane traffic on TDM lines.

Hardware architecture for Integrated MSS

CDSU

TGFP

BDCUPAUMCCSUBSUMFSUCASU

CHU OMUSTUVLRUCMCMU

PSTN

PBX

NSS

BSS

LAN LAN LAN

VDU and LPT

X.25

ET

GSW

CCMU

MESSAGE BUS

ET

ET

ECET

CLSEXT. SYNC

VANG

O&M LAN Switch

IPET

LAN

IP Trunk

TGSU

IP

IP Control PlaneLAN Switch

IP User PlaneLAN Switch

The BSU and VLRU are partof the Integrated MSS,not the GCS.

Fig. 3 Hardware architecture for integrated MSS


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2.2 Gateway Control Server (GCS)

Presented in Figure below is the block diagram of the GCS. It shows the interfaces between the functional units and also the interfaces connecting the system to the environment. A more detailed description of the functionality each unit performs is given below in section Functional Units.

The real benefit of the GCS is that it can also be used for controlling the MGWs used for interworking between the PSTN/ISDN and the IP Multimedia Subsystem (IMS). The GCS also contains the Session Initiation Protocol (SIP) protocol, used as a session control protocol in All- IP networks.

Hardware architecture for GCS

CMUSTMSTM1 or OC3

CMUCCSU

E1 or T1

Optional TDM HW

CMUETGSW

GSW

CMUCLSCMUCHU

CMUCMU

EMBEMB

CMUSTU

CMUCHU

CMUOMU

CMUBDCU

SWUSWU

O & M LanExt. Sync.

I /O alarms

VDU & LPT

CMUSU Control Lan

CMUCMM

SU = SIGU, PAU, SCPUAmount of signaling units: SIGU+1 + PAU + 1 + SCPU+1 = SU

SWUSWU

CMUSTMSTM1 or OC3

CMUCCSU

E1 or T1

Optional TDM HW

CMUETCMUETGSW

GSWGSW

GSW

CMUCLSCMUCLSCMUCHUCMUCHUCMUCHU

CMUCMUCMUCMU

EMBEMB

CMUSTUCMUSTU

CMUCHUCMUCHUCMUCHU

CMUOMUCMUOMUCMUOMU

CMUBDCUCMUBDCU

SWUSWU

O & M LanExt. Sync.

I /O alarms

VDU & LPT

CMUSU Control Lan

CMUCMMCMUCMM

SU = SIGU, PAU, SCPUAmount of signaling units: SIGU+1 + PAU + 1 + SCPU+1 = SU

SWUSWUSWUSWU

Fig. 4 Hardware architecture for GCS

Note that GCS does not have following units:

Base Station Signaling Units (BSU) is not furnished because the GCS does not handle signaling or control traffic towards radio networks. These units are available in MSS.

Visitor Location Register Units (VLRU) is not furnished in the GCS because subscriber information is handled in the visited MSS where these units are available.


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2.3 Circuit Switched Data Server (CDS)

CDS is a new delivery when having a standalone MSS for handling data call traffic. Operating principle of CDS is shown as follows:

Operating principles for CDS

BSS/RAN PSTN/ISDN

MGW MGW

MSSMSS

CDSCDS

CDSU

H.248/Megaco

IWF control

interface

TDM/PCM

Ta Tb

Fig. 5 CDS Operating principle

The block diagram of the network element (see figure below) shows the interfaces between the functional units and the interfaces that connect the system to the environment.


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Hardware architecture for CDS

CMUCMM

EMBMB

CMUCDSU

CMUOMU

SWUSWUO & M Lan andControl Lan

CMUCLSExt. Sync.

GSW

I/O alarms

VDU & LPT

CMUETE1 or T1

CMUSU

CMUN+1

CMU2N

CMUCMUPair2N

N orPOOL

CMUSTMSTM1 or OC3

GSW

CMUCMMCMUCMM

EMBMB

CMUCDSUCMUCDSU

CMUOMUCMUOMUCMUOMU

SWUSWUO & M Lan andControl Lan

CMUCLSCMUCLSExt. Sync.

GSW

I/O alarms

VDU & LPT

CMUETCMUETE1 or T1

CMUSUCMUSU

CMUN+1

CMU2N

CMUCMUPair2N

N orPOOL

CMUN+1CMU

N+1

CMU2NCMU2N

CMUCMUPair2N

CMUCMUCMUPair2NCMUPair2N

N orPOOL

CMUSTMSTM1 or OC3

GSW

Fig. 6 Hardware architecture for CDS


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3 Cabinet Types


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3.1 MSS & GCS Cabinet Types

At system level M14, the MSS has three cabinet types:

Release M14 A Cabinet (14AC)

Release M14 B Cabinet (14BC)

Release M14 C Cabinet (14CC)

All these cabinet types have fixed cartridge configurations. Although they may be only partially equipped if the customer does not need to utilize the full network element capacity, each cartridge in the cabinet accepts only a functional unit of certain type. All cartridges are installed in the cabinets at the factory.

When installed, each cabinet is identified as a specific MSS cabinet (for example 14BC 0) by installing the appropriate interconnection cable set for connections to the other MSS cabinets, along with the necessary wiring connectors (most of the wiring connectors are installed at the factory).

The 14AC, 14BC and 14CC cabinets as new delivery always use the Ethernet-based Message Bus (EMB) LAN.

Minimum configuration in M14 is to have cabinet 14AC alone.

Additionally if TDM connection is still being used, 14CC needs to be installed.


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New Standalone MSS/GCS Cabinets in M14

0 1 21B 1C 1D

Minimum

Fig. 7 Standalone MSS/GCS cabinets in M14

MSS and CDS floor layout

Fig. 8 MSS and CDS floor layout


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3.2 Integrated MSC (MSCi) Cabinet Types

The Integrated MSS features the following cabinet types:

Main Operation and Maintenance Cabinet (MOMC)

VLR and General Signaling Cabinets (VLRC and GSC)

GSW and ET Cabinets (GSWC and ETC)

Interworking function Cabinet (IWC)

Integrated MSS/GCS cabinets

Fig. 9 Integrated MSS/GCS cabinets


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3.3 CDS Cabinet Type

As shown in figure, minimum configuration for CDS consists of IPCC and IWC (two cabinets) while maximum configuration are up to 5 cabinets with three more IWC cabinets.

When installed, each cabinet is identified as a specific CDS cabinet (e.g. IWC0) by installing the appropriate interconnection cable set for connections to the other CDS cabinets, along with the necessary wiring connectors (most of the wiring connectors are installed at the factory). Illustrated in the figure below are the cabinets used in the CDS.

CDS cabinets

Fig. 10 CDS cabinets


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4 Functional Units


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In MSS Standalone, cabinets 14AC, 14BC and 14CC replacing the IPCF, IPCG and IPCH cabinets on the previous version, are introduced while there is no difference in MSS Integrated version.

4.1 Ethernet-based Message Bus (EMB)

Compare to M13, new functional unit in M14 new delivery is so called Ethernet-based Message Bus (EMB) which enables higher capacity and reduced footprint in the MSS. In the standalone MSS, the existing Message Bus (MB) can be replaced with the EMB. The EMB can also be used when switching from an integrated MSS to an MSSu.

The LAN topology used in the EMB is a switched LAN. Each computer has a point-to-point connection to a cabinet level LAN switch, ESB26 or compatible. These LAN switches are further connected to a second stage LAN switch, ESB14-A or compatible.ESB14-A is used as second level Ethernet switch to enable the interconnection between first level Ethernet switches in EMB configurations.ESB14-A is a 14-port managed Ethernet switch integrated into the M98 mechanics. ESB14-A has 10 optical gigabit Ethernet ports All connections are full duplex. The speed of links between computers and cabinet level LAN switches is 100 Mbps and the speed of links connecting the cabinet level LAN switches to the second stage LAN switches is 1 Gbps. To achieve redundancy, the LAN of the EMB LAN is duplicated.

In the future, it is possible to upgrade the cabinet-level LAN switches to offer 1 Gbps speed also in the downlink direction towards the computer units by changing the ESB26.

The EMB requires the use of CP816-A or compatible processor plug-in units, which have four Ethernet ports. Two ports are used for EMB LANs and two ports for external LANs. The EMB LANs are totally separated from the external LANs (for example for control plane and O&M) of the network element.


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Ethernet-based Message Bus

100Mbps

1Gbps

ESB26

OMU,1OMU,0CCSU,2CCSU,1CCSU,0

ESB26

HLRU,0,0 HLRU,0,1HLRU,1,0 HLRU,1,1

1Gbps

100Mbps

EMB,0

EMB,1

Second stage switch

Cabinet level

switches

Computers

ESB14-A

ESB14-A

ESB26 ESB26

Fig. 11 EMB LAN topology


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4.2 14A Cabinet (14AC)

The 14AC cabinet contains, among other units, the functional units which handle the key operation and maintenance tasks in the MSS. The network element always has one M14 A cabinet, which includes in its maximum configuration:

ten Signaling Units (*SU), configurable as BSU, IDEU, SCPU or SIGU

two Visitor Location Register Units (VLRU) which can be replaced with *SUs in the GCS functionality

one Statistical Unit (STU) pair

one Charging Unit (CHU) pair

Clock Buffer Units (CLBU) installed in CLAC-B cartridges

one Central Memory and Marker Unit (CMM) pair

one Operation and Maintenance Unit (OMU) pair

one Cellular Management Unit (CMU) pair

two Basic Data Communications Units (BDCU)

ten SWU units for control LAN, billing LAN, O&M LAN and LAN management

four Fan Tray Units (FTRB-A) to ensure forced ventilation

14AC cabinet

Fig. 12 Equipment in the 14AC cabinet in MSS


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4.2.1 Central Memory and Marker (CMM)

The CMM contains the functionality of Central Memory, Marker (optional) and Common Channel Signaling Management Unit in the same functional unit. The central memory handles the routing functions of the MSS. It also contains all system configuration data and master copies of distributed files. In addition, it is responsible for the central functions of CCS7.

The Marker controls and supervises the GSW, hunts for free circuits and is responsible for establishing and releasing all connections. The Marker and the GSW make up a switch-over entity, which is duplicated for 2n redundancy.

The MSC Server contains two CMMs, which are located in the 14AC cabinet.

Central Memory and Marker (CMM)

• Function: CMM contains

the functionality of the CM,

Marker (optional), and

CCMU in the same

functional unit.

• Redundancy: 2n

Fig. 13 CMM in a DC3C-B cartridge


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4.2.2 Cellular Management Unit (CMU)

The CMU controls the cellular radio network. The MSC Server contains two CMUs in 14AC cabinet.

Cellular Management Unit (CMU)

• Function:The CMU

controls the cellular radio

network.

• Redundancy: 2n

Fig. 14 CMU in a DC4C-B cartridge


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4.2.3 Statistical Unit (STU)

The STU collects raw traffic measurements, supervises the load of the exchange, maintains various counters and produces statistical reports. Primarily statistical reports are sent to IP network via OMU functional unit and FTP protocol. Only OLCM reports and fraud reporting are transported using redundant LAN interface available in STU. MSC Server can have only one STU pair.

Statistical Unit (STU)

• Function:The STU

collects raw traffic

measurements,

supervises the load

of the exchange,

maintains various

counters and

produces statistical

reports.

• Redundancy: 2n

Fig. 15 STU in MC2C-A cartridge


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4.2.4 Charging Unit (CHU)

The CHU collects charging data, maintains various counters and produces detailed charging records. The CHU can send charging data directly from its redundant LAN interface to Billing Centre using FTP over TCP/IP.

Additionally to the use of SONY MO91 as an external storage disk, it is now from M14.0 onwards introduced a new mass memory device known as Blu-Ray DVD for replacing the old storage device which is however can still be used.

The Blu-Ray DVD is not automatically part of the CHU sales item: it is possible to choose between the CHU with the Blu-Ray DVD option and the CHU without the Blu-Ray DVD option. All CHUs must, however, be similarly equipped.

Charging Unit (CHU)

• Function:The CHU

collects charging data,

maintains various

counters and

produces detailed

charging records.

• Redundancy: 2n

Fig. 16 CHU in a MC2C-A cartridge


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4.2.5 Operation and Maintenance Unit (OMU)

The OMU handles all centralized supervision, alarm and recovery functions, and the connections towards user interface (MMI-System). Primarily the connections are made using IP network but V.24 interface is also available.

The OMU collects the wired alarms from the exchange as well as from the external equipment connected to the system.

The OMU has dedicated storage devices, which serve as a storage, for example, for the entire system software of the network element as well as for the event buffer for intermediate storing of alarms.

The OMU provides:

Telnet connection for MMI

FTP and NSN specific EMT connection to NEMU for NEMU applications

HTTP connections to NetAct for delivering alarms in XML format

The MSC Server contains one OMU pair and it is located in this cabinet. The OMU unit includes also a mass memory unit.

In M14.0 new deliveries Sony MO91 devices are replaced with the Blu-Ray DVDs.

Operation and Maintenance Unit (OMU)

Function:

• handles all centralised supervision,

alarm and recovery functions

• handles the connections towards user

interface. The connections are made

using IP network or via V.24 interface.

• collects the wired alarms from the

exchange as well as from the external

equipment connected to the system.

• has dedicated storage devices, which

serve as a storage for the entire

system software of the network

element as well as for the event buffer

for intermediate storing of alarms.

Redundancy: 2n

Fig. 17 OMU pair and mass memory in CC4C-A cartridges


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4.2.6 Basic Data Communication Unit (BDCU)

The BDCU provides communication links to the operation and maintenance network, to the SMS Center and to the Billing Center.

The BDCU provides the following external interfaces:

analogue X.25

digital X.25

LAN/Ethernet

Basic Data Communication Unit (BDCU)

Function:The BDCU provides

communication links to the operation

and maintenance network, to the SMS

Center and to the Billing Center.

The BDCU provides the following

external interfaces:

• analog X.25

• digital X.25

• LAN/Ethernet

Redundancy: n BDCU in MC2C-A cartridge

Fig. 18 BDCU in MC2C-A cartridge


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4.2.7 Clock System (CLS)

Both CLBU (Clock and Alarm Buffer Unit) and CLSU (Clock System Unit) are part of the Clock System (CLS).

The CLBU distributes the clock and synchronization signals within the same cabinet. The CLBU also collects the wired alarms from the units whose timing it handles and transfers them to the OMU.

The CLSU generates the clock and synchronization signals and transmits them further to the CLBU units in the other cabinets. The CLSUs also feed the timing signals to, and collect the wired alarms from the units in the 14AC and send them further to the OMU.

In the integrated models synchronization signal is received from external TDM lines or from external synchronization interface in CLS.

In the standalone models without external TDM connections there is a need to receive external synchronization signal via external synchronization interface in CLS. This external synchronization signal is needed to ensure the accuracy of charging and also to ensure that timestamp information in charging data and performance data from different network elements are comparable.

The MSC Server contains one duplicated CLSU which is located in the 14AC cabinet and the maximum number of CLBU is 9 pairs.

Clock System (CLS) 1/2

CLSU

CLBU CLBUCLBU CLBU

CLS includes CLSU (Clock System Unit) and CLBU (Clock and Alarm Buffer

Unit)

Fig. 19 CLSU and CLBU


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Clock System (CLS) 2/2

Clock System Unit (CLSU)

• Function:

• The CLSU generates the clock and synchronization

signals and transmits them further to the CLBU units

in the other cabinets.

• The CLSU also collects the wired alarms from the

units in the 14AC and send them further to the OMU.

• Redundancy:2n

Clock and Alarm Buffer Unit (CLBU)

• Function:

• The CLBU distributes the clock and synchronisation

signals within the same cabinet.

• The CLBU also collects the wired alarms from the

units whose timing it handles and transfers them to

the OMU.

• Redundancy:2n

Two independent

CLSUs in a CLOC-

B cartridge

Two independent

CLBUs in a CLAC-

B cartridge

Fig. 20 CLSU in a CLOC-B cartridge & CLBU in a CLAC-B cartridge


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4.2.8 LAN Switch Unit (SWU)

The LAN switch units collects signaling data from the BSUs, CCSUs, SCPUs and SIGUs, and O&M signaling data from the OMU, BDCUs and STU/CHU units and sends it further to the IP network via external LAN switches and routers with a uplink connection.

In M14 system level, the LAN switch units are also used in Ethernet Based Message Bus.

Notes:

ESB26:LAN switch unit (2 optical Gbit/s, 2 electrical Gbit/s and 2 100 Mbit/s electrical uplinks; 20 100 Mbit/s electrical downlinks)

ESB14-A:LAN switch unit (10 electrical Gbit/s uplinks;4 downlink 10/100 Mbit/s ports)

LAN Switch Unit (SWU)

Function:

• collects signalling data from the BSUs, CCSUs, SCPUs and SIGUs and sends it further to the IP network via external LAN switches and routers with a uplink connection.

• collects O&M signalling data from the OMU, BDCUs and STU/CHU units and sends it further to the IP network via external LAN switches and routers with a uplink connection.

• In M14 system level, the LAN switch units are also used in Ethernet Based Message Bus.

Redundancy: 2nSWU in LASWC-A cartridge

Fig. 21 LAN SWU


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4.2.9 Visitor Location Register Unit (VLRU)

The VLRU contains information of each subscriber currently served by the MSC Server. The MSS can contain up to 7 VLRU pairs and in the M14 system level of standalone MSS, it can support up to 2.5 million subscribers.

Visitor Location Register Unit (VLRU)

Function:The VLRU contains information of each subscriber currently

served by the MSC Server.

Redundancy: 2n

Fig. 22 VLRU in a MC2C-A cartridge


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4.2.10 Signaling Unit (SIGU)

The Signaling Unit (SIGU) has the functionality of the Common Channel Signaling Unit (CCSU), except that the SIGU can utilize only an IP-based signaling network, whereas the CCSU can use an IP or a TDM -based SS7 network.

Signalling Unit (SIGU)

Function:The SIGU has the functionality of the CCSU, except that the

SIGU can utilize only an IP-based signaling network.

Redundancy: n+1

Fig. 23 SIGU in a MC2C-A cartridge


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4.2.11 Base Station Signaling Unit (BSU)

The BSU provides BSSAP and RANAP protocols that perform the signaling functions between radio networks and MSS. The BSU has SIGTRAN functionality and a LAN interface which enable it to use IP for conveying signaling messages. If the A-interface is connected directly to the Integrated MSS, then the BSU also controls the TDM lines linked to the GERAN.

Base Station Signalling Unit (BSU)

Function:

• The BSU provides BSSAP and RANAP protocols that perform the

signalling functions between radio networks and MSS.

• The BSU has SIGTRAN functionality. If the A-interface is connected

directly to the Integrated MSS, then the BSU also controls the TDM

lines.

Redundancy: n+1

Fig. 24 BSU in a MC2C-A cartridge


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4.3 14B Cabinet (14BC)

The 14BC cabinet contains, among other units, most of the signaling units of the MSS. The network element can have one to three 14BC cabinets. The 14BC cabinet can be added to M13 MSS after EMB upgrade. The 14BC cabinet includes in its maximum configuration:

one Charging Unit (CHU) pairs

three to seven Visitor Location Register Unit (VLRU) pairs which can be replaced with *SUs in the GCS functionality

twenty-one Signaling Units (*SU), configurable as BSU, IDEU, SCPU and SIGU

one Indirect Access Unit (INDU) pair which can replace the CHU pair, optional

one Integrated Extension Unit (IEU) pair which can replace six *SUs, optional

eight SWU units for EMB LAN and control LAN

14 BC has the similar functional units in 14AC, and there is an option to installed Indirect Access Unit (INDU) in 14BC.

14BC cabinet

Fig. 25 Equipment in the 14BC cabinet in the MSS


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4.3.1 Indirect Access Unit (INDU)

The Indirect Access Unit enables an indirect connection for such service providers, which do not have their own physical subscriber circuits to the exchange. One CHU (second pair) can be replaced with INDU unit which has the same configuration as the CHU pair. INDU has a database of 4M subscribers and 600k BHCA capacity or fixed access.

Indirect Access Unit (INDU)

Function:The INDU

enables an indirect

connection for such

service providers,

which do not have

their own physical

subscriber circuits to

the exchange.

Redundancy: 2n

Fig. 26 INDU in MC2C-A cartridge


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4.4 14C Cabinet (14CC)

The 14CC cabinet is an optional cabinet type in the MSS, and it is mainly used for CCS7 signaling purposes and PBX connections. It houses Exchange Terminals (ET), the Group Switch (GSW) and signaling units, configurable as Common Channel Signaling Units (CCSU) and/or Primary Rate Access Unit (PAU). The network element can have one 14CC cabinet, which includes in its maximum configuration:

eighteen Common Channel Signaling Units (CCSU), configurable as Primary Rate Access Units (PAU)

one Group Switch unit (GSW2KB) pair

two GT4C-A cartridges equipped with up to two ETS2 plug-in units and up to six ET16 plug-in units

four SWU units for EMB LAN and control LAN, housed in LANU cartridges

four Fan Tray Units (FTRB-A) to ensure forced ventilation

14CC cabinet

Fig. 27 Equipment in the 14CC cabinet in the MSS


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4.4.1 Common Channel Signaling Unit (CCSU)

CCSU handles CCS7 signaling functions towards both PSTN and the other network elements in the SCN. CCS7 signaling traffic can be carried over both PCM lines (TDM) and the IP network with SIGTRAN.

CCSU also handles MEGACO (Media Gateway Control) signaling.

When TDM is in use, CCSU also controls the PCMs running to both PSTN and the other network elements in the SCN.

In the standalone models SIGU is used instead to handle signaling using SIGTRAN and CCSU is used in standalone models only in the optional 14CC. Maximum number of CCSUs is 18 pcs.

Common Channel Signalling Unit (CCSU)

Function:

• handles CCS7 signalling functions towards both PSTN and the other network elements in the SCN. CCS7 signalling traffic can be carried over both PCM lines (TDM) and the IP network with SIGTRAN.

• handles MEGACO (Media Gateway Control) signalling.

• controls the PCMs running to both PSTN and the other network elements in the SCN.

Redundancy: n+1

Fig. 28 CCSU in DC3C-B cartridge


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4.4.2 Group Switch (GSW)

The GSW is the switching fabric of the MSS, and the Marker controls and supervises the GSW.

At system level 14 the GSW2kB is introduced, which is especially suitable for network elements that require a small-sized switch.

The GSW2kB is a scalable bit-based Group Switch system providing capacity levels from 256 to 2048 PCMs in a single network element.

On hardware level, the GSW2kB concept is implemented as SW256B plug-in unit. The maximum capacity is reached by using 8 x SW256B plug-in units. The SW256B plug-in-unit can be used simultaneously in the same cartridge with the existing SW128B plug-in-unit.

STM-1 and ET16 require the GSW2kB.

Group Switch (GSW)

Function:

• The GSW is the switching fabric of the MSS, and the Marker controls and supervises the GSW.

• At system level M14 the GSW2KB is introduced. GSW2KB is a scalable bit-based Group Switch system providing capacity levels from 256 to 2048 PCMs

Redundancy: 2n

Fig. 29 GSW2KB in SW10C-A cartridge


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4.4.3 Exchange Terminal (ET16 & ETS2)

The ET performs the electrical synchronization and adaptation of an external TDM line. It is able to do the HDB3/AMI/B8ZS coding and decoding, insert the alarm bits in the outgoing direction, and produce the PCM frame structure. In the MSS the ET is furnished in the optional 14CC cabinet.

At system level M14, ET16 is introduced, which increases the capacity up to 16 PCM lines in one card. The PCM connections are on the back plane. This is the most effective way to handle the cabling arrangements, although it sets the requirement to have the cabling panel in all network elements using the ET16.

The ET16 interface can be used in the MSS with the optional TDM cabinet. The same plug-in-unit ET16 can be used for both symmetrical, coaxial and ANSI interfaces.

STM-1/OC-3 is the common interface at sites. In M14.0, the new M98Amechanics enables integrating the STM-1/OC-3 interface. As the integrated STM-1/OC-3 interfaces can be managed by the same O&M interface, considerable savings can be achieved.

ETS2 is a new plug-in-unit for STM-1/OC-3 Terminal Multiplexer. It has two STM-1/OC-3 optical interfaces and it frames, maps and multiplexes 2x 64 2.048 Mbit/s tributaries into SDH STM-1 frame and vice versa. In SONET OC-3 mode, ETS2 frames, maps and multiplexes of 2x84 1.544 Mbit/s tributaries into SONET STS-3 frame and vice versa.

ETS2 supports MSP 1+1 protection for transmission. All fibers are connected to the same plug-in-unit.

With the new optional 14CC TDM cabinet, STM-1 is available also for the existing MSC Servers.


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Exchange Terminal- ET16 & ETS2

Function: The ET performs the electrical synchronization and adaptation of an external TDM line. It is able to do the HDB3/AMI/B8ZS coding and decoding, insert the alarm bits in the outgoing direction, and produce the PCM frame structure.

ET16: provides 16 E1 interfaces

ETS2: provides 2 STM-1 interfaces

Redundancy: nETS2 & ET16 in GTIC

cartridge

ETS2 ET16

Fig. 30 ETS2 and ET16 in the GTIC cartridge


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4.5 CDS in standalone mode

It consists of 2 cabinets, which are:

IP Cabinet C (IPCC)

Interworking Cabinet (IWC)

All CDS cabinet types have fixed cartridge and functional unit configurations. Although they may be only partially equipped, if the customer does not need to utilize the full capacity, each cartridge in the cabinet accepts a functional unit of only certain type. All cartridges are installed in the cabinets at the factory.

The cabinets have always the same functional units in the same positions regardless of the position of the cabinet in the layout or its index number.

The CDS functional units are CMM, OMU, CLSU, CLBU, CDSU, SIGU, MB, GSW, ET, LANU.

4.5.1 Compact Data Service Unit (CDSU)

The CDSU implements the Inter Working Function (IWF) of the MSCi, Compact MSCi and CDS. A G.703 connection is used. The main task of the unit is to adapt the data connection of the terminal device (i.e. laptop PC) of the GSM Mobile Station (MS) to the:

Public Switched Telephone Network (PSTN)

Integrated Services Digital Network (ISDN)

The tasks of the CDSU include:

Rate Adaption (RA)

Radio Link Protocol (RLP) processing

Layer 2 interface (L2R)

Modem state control

The CDSU offers the following GSM data services:

Asynchronous bearer services

Transparent synchronous bearer services

Transparent facsimile group 3 teleservice

The equipping of the cartridge depends on the application. There are three options for the CDSU:

a Normal Speed Data Service Unit with Data Interface, NDSD Pool, or an UDI Pool

a Normal Speed Data Service Unit with Modems, NDSM Pool, or a Modem Pool

a Compact Data Service Unit Pool, CDSU Pool, or a General Pool (which combines both of the above).


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The CDSU supports, when fully equipped, 32 simultaneous calls (no matter whether the call is using single or multi-slot configuration in the air interface). If the CDSU hardware is configured as

NDS; it supports 32 simultaneous modem/fax calls.

NDSD; it supports 32 simultaneous UDI calls

CDSU; it supports 32 simultaneous modem/fax/UDI calls.

In the NDSM and CDSU mode the use of channels is dynamic (modem, fax, UDI), that is, the reserved channel is configured based on the received call set up request. So, for example, the CDSU can serve simultaneously any number of modem/fax/UDI calls (the total number of calls per CDSU is limited to 32).

Compact Data Service Unit (CDSU)

Function: The main task of the

CDSU is to adapt the data

connection of the terminal

device (i.e. laptop PC) of the

GSM Mobile Station (MS) to

PSTN or ISDN.

Redundancy: n

Fig. 31 CDSU General Pool in a DS1C-B/DS1C-A cartridge


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5 Redundancy

2NVLRU

2NSWU

2NSTU

N+1SIGU

2NOMU

2NMB

2NINDU

NET

2NEMB

2NCMU

2NCMM

2NCM

2NCHU

N+1CCSU

2NCCMU

N+1BSU

NBDCU

RedundancyUnit

Fig. 32 Redundancy methods of functional units


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6 Capacity in M14

Fig. 33 Capacity M14 in MSS, GCS, MSCi and CDS


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7 Glossary 2G 2nd Generation mobile phone network 3G 3rd Generation mobile phone network 3GPP Third Generation Partnership Project AC Apply Charging ACR ApplyChargingReport API Application Programming Interface APSE Application Server AUC Authentication Centre BSSAP Base Station Subsystem Application Part CAMEL Customized Applications for Mobile Network Enhanced Logic CAP CAMEL Application Part CDR Charging Data Record CHU Charging Unit CM Central Memory CMISE Common Management Information Service Element CORBA Common Object Request Brokerage Architecture CPS Connection Processing Server CPU Central Processing Unit CUE Continue CS Circuit Switched DCN Data Communications Network DP Detection Point DTMF Dual Tone Multifrequency EDGE Enhanced Data Rates For GSM FTP File Transfer Protocol GCS Gateway Control Server GERAN GSM/EDGE Radio Access Network GPRS General Packet Radio Service GSM Global System For Mobile Communications GSW Group Switch HLR Home Location Register HSS Home Subscriber Server IDP Initial DP operation IMS IP Multimedia Subsystem IMSI International Mobile Subscriber Identification IN Intelligent Network INAP Intelligent Network Application Part IP Internet Protocol ISUP ISDN User Part LA Location Area M Marker M3UA MTP3 User Adaptation MAP Mobile Application Part MGCF Media Gateway Control Function MGW Multimedia Gateway MMI Man Machine Interface MML Man Machine Language MS Mobile Station MSC Mobile Switching Centre


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MSS MSC Server MSSu Upgraded MSC Server NEMU Network Element Management Unit O&M Operation & Maintenance OMU Operational And Maintenance Unit PLMN Public Land Mobile Network PSTN Public Switched Telephone Network PVC Permanent Virtual Connection RAN Radio Access Network RANAP Radio Access Network Application Part RNC Radio Network Controller RTP Real Time Protocol SCP Service Control Point SCTP Stream Control Transmission Protocol SIGTRAN Signaling Transport SIP Session Initiated Protocol SMSC Short Message Service Centre SPVC Soft Permanent Virtual Connection SRR Service Routing Register SSP Service Switching Point SS7 Signaling System # 7 STU Statistical Unit SVC Switched Virtual Connection TMSI Temporary Mobile Subscriber Information T-SGW Transport Signaling Gateway UE User Equipment UMTS Universal Mobile Telecommunication System USB Universal Serial Bus USSD Unstructured Supplementary Services Data UTRAN UMTS Terrestrial Radio Access Network VLR Visitor Location Register VMSS Visited MSC Server

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