03_cn34015en40gla3 Mgw for Mss_doc

7/25/2019 03_cn34015en40gla3 Mgw for Mss_doc

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CN60004EN40GLA1 2011 Nokia Siemens Networks

1

Content

1 Objectives 3

2

Functionality of MGW 5

2.1 Capacity and Performance 9

3 MGW Functional Units 11

3.1 Functional units in Open MGW 11

3.2 Functional units in MGW based on IPA2800 13

3.3 Switching and Multiplexing Units 32

4 MGW Hardware Configuration 51

4.1 Hardware changes in release U5.0 58

4.2 MGW release upgrade to U5.0 58

5 Phasing of features in MGW 59

5.1 U5 Features 59

6

Glossary 65

MGW for MSS


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2011 Nokia Siemens Networks2


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1 ObjectivesAfter completing this module, the student should be able to:

List the main functions of the MGW for MSS

Explain the main functions of each functional unit

List the redundancy principles for the functional units

Identify the interfaces implemented in the MGW

Explain the MGW hardware configuration


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2 Functionality of MGW


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The MGW functionality is based on the architecture model of 3rd

GenerationPartnership Project (3GPP) Release 4 and Release 5 networks. The functionalities ofMGW are implemented mainly according to the latest 3GPP release specifications.

The main function of MGW is to provide the link between different networks by actingas a gateway for both media (user data) and signaling (control data).

MGW performs the following main functions.

User plane transport

MGW terminates the user plane from circuit-switched network type of interfacesand packet-based interfaces, and does the transport conversion between theseinterfaces. If transcoding is required for the user plane, it is performed with thetranscoders which are integrated in MGW.

Media processing and speech enhancements

MGW provides automatic level control (ALC), echo cancelling, acoustic echocancelling (AEC), noise suppression (NS), comfort noise generation, enhancedvoice activity detection (eVAD), continuity check and dual-tone multifrequency(DTMF) generation and detection functions to circuit-switched network connectionsaccording to service requirements. MGW can also generate tone and voiceannouncements for the user plane, as well as create conferences for multipartyconnections.

Signaling transport

SS7 type of signaling between network interfaces and MSC Server can be routedthrough MGW. MGW performs a transport change for the signaling traffic betweenpacket-switched and circuit-switched interfaces without affecting the signalingapplication layers. MGW supports high capacity 2 Mbit/s or 1.5 Mbit/s signalinglinks according to the Q.703 Annex A.

IP/ATM Quality of Service (QoS)

MGW supports different features for IP transmission quality management, and forATM transmission quality management in MGW based on IPA2800. The featuresinclude, for example, IETF DiffServ DSCP marking for user plane, control planeand O&M traffic, Multiple Isolated IP Networks, IP Connection Admission Control(CAC), as well as configurable Jitter buffer eliminating the jitter (transmission delayvariation) that occurs in the external IP networks.

Transcoder-free connectionsTranscoding between different codecs decreases the speech quality. MGWenables transcoder-free connections by supporting tandem-free operation (TFO)and transcoder-free operation (TrFO) features for 2G, 3G and SIP calls. With TFOPayload optimization and TrFO IP bandwidth transmission can be optimized.Speech enhancements are also provided for transcoder-free connection.


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Sharing resources between several controllers

Several MSC Servers can share the resources of one MGW. Only TDM resourcesin MGW are dedicated to a certain controller, and all other resources are sharedbetween all controlling devices.

Service to both circuit-switched core network and convergence networksfrom one network element

The MGW of the MSS System can also serve traffic coming from convergencenetworks, when SIP-based services are gradually deployed to the network.

Dual IP stacks

Both IPv4 and IPv6 are supported in MGW for user plane, control plane, and O&Mtraffic. This dual stack implementation allows the operator to use both IP versions

on the network in parallel. Codec and bearer modification

Bearer and codec modification is needed to ensure proper functionality of thefollowing features:

o TrFO

o TFO, with payload optimization mode

o Fax and modem transport

o Supplementary services of the IMS and the Mb interface\

Codec modification is possible between any compressed codec and G.711 and

also between two compressed codecs. Any compressed codec and G.711 can bemodified to clearmode or T.38 with data and fax calls.

Network functions, like handovers, or service interactions in MSS system may leadto a situation where multiple transcodings take place in the speech. This causesextra delay and degraded speech quality. Modifying the Nb interface codecensures that the number of transcodings is always minimized in a speech call.During codec modification, the user plane bearer is also modified to suit the newcodec when necessary.

Text Telephony (TTY)

TTY is a functionality that enables text-based communication over a speech

bearer. This functionality is mainly intended for people with impaired hearing orspeech who require the use of text telephony. The feature is specified by ITU-T.MGW performs the required ITU-T V.18 and cellular text telephony modem (CTM)signaling (specified by 3GPP) conversation and adaptation for transmitted text.

TDM-TDM, TDM-IP, and ATM-ATM cross connect capability

In both Open MGW and MGW based on IPA2800 semi-permanent connectionscan be created between two circuit-switched bearer channels (TDM time slots),between circuit-switched bearers and IP bearers.

MGW based on IPA2800 has the ability to act as an ATM switch for incomingvirtual channels (VCs). These VCs can be connected with management

commands to other network elements, thus enabling optimal usage oftransmission network.


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ATM AAL type 2 nodal function capability in MGW based on IPA2800

If AAL type 2 is used and the network is too big for configuring permanent virtualchannels (PVCs) in a full mesh, AAL type 2 switches are needed to connect AAL

type 2 paths from one PVC to another. AAL type 2 nodal function in MGWs can beused for this purpose over ATM backbone connections similarly as for routing theIur between RNCs for inter-RNC purpose.

MGW in Bearer Independent Circuit Switched Core Network

MSS MSS,

I-BCFNc

BICC, ISUP, SIP-I

HLR-FE

MGW MGW,

I-BGF

Nb

IP, ATM, TDM Backbone

Mc

H.248

Mc/Mn

H.248

subscriber database

IN

BSC

RNCWCDMA

Iu-CS

GSM

AoIP, Ater

TC

A

A

PSTN/ISDN

VoIP/IMS/SIP

Other PLMNSIP,SIP-I,

BICC

PSTN

Mb/Nb(SIP-I)/Nb

Mb

Fig. 1 MGW in bearer independent circuit switched core network

Typically, MSS handles several gateways. Multimedia gateways provide thepossibility to create virtual gateways in one physical gateway element so that it offersmedia resources to several controlling elements. This multi-hosting functionality, alsoknown as MGW tandeming and virtual MGW (vMGW), in the gateway givesoperators flexibility to use the network elements optimally, depending on the networkarchitecture.


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2.1 Capacity and Performance

Nokia Siemens Networks Multimedia Gateway (MGW) media processing capacity inall-IP networks is 80,000 Erlangs in MGW base on IPA2800 and 100,000 Erlangs inOpen MGW. In the all-IP solutions, MGW provides Gigabit Ethernet connectivitytowards surrounding networks, such as GSM, WCDMA, and PSTN/PLMN.

MGW capacity and hardware configuration depend on network characteristics:interface types, traffic density and traffic profile. Interface capacity is evaluatedaccording to traffic volumes and used voice codecs. User plane processing need isthen evaluated according to estimated DSP service needs: how large a portion ofcalls need transcoding, echo cancellation, interworking functionality and so on.

The following table present connectivity capacity details for Open MGW and MGWbased on IPA2800.

Capacity in MGW (Open MGW)

Type of connectivity Number of interfaces

TDM STM-1/OC-3 80 + 80

IP for user plane (GE) 24 + 24

IP for user plane (10GE) 6 + 6

IP for control plane (GE) 1 + 1

IP for control plane (10GE) 1 + 1

IP for O&M 2 + 2

Fig. 2 Open MGW connectivity capacity


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Capacity in MGW (MGW based on IPA2800)

Type of connectivity Number of interfaces

TDM STM-1/OC-3 56 + 56

IP for user plane (GE) 16 + 16

ATM STM-1/OC-3 56 + 56

TDM E1/T1 1440

IP for control plane with L2 1 +1

IP for O&M with L2 2 + 2

IP for control plane with L3 1 + 1

IP for O&M with L3 1 + 1

Fig. 3 MGW based on IPA2800 connectivity capacity.


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3 MGW Functional Units

3.1 Functional units in Open MGW

Functionality is distributed to a set of nodeswhich can accomplish special purposes.These nodes are entities of hardware and software, or only hardware. The softwarein the nodes is further divided into individual recovery unitsthat have their own stateand role in the system. The states of recovery units in the same node can beindependent of each other.

The following figure illustrates functional units (nodes) in open MGW.

Functional Units (Nodes) in Open MGW

AMCCarrier

RTM

TCU

TCUTCUTCU

IP signaling

TCUISU

TCUCLAO&M

RTM

FI

BI

RTMSync. clock

AMCCarrier

TCUIPNI1IP/GE

TCUIPNI10IP/10GE

TCUTDMSNI

IP User Plane

ADDF

TDM User

Plane and

signalling

TDM STM-1/OC3TDM E1/T1

HubHub

FI&BI between shelves

Fig. 4 Functional units (nodes) in Open MGW


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3.1.1 Operation, Maintenance and Signaling Node (CLA)

CLA contains basic system maintenance functionality and serves as an interface

between the gateway and a higher level network management system or user. Theexternal O&M traffic is terminated directly on the CLA node. CLA handles all centralMGW functions as well as the same tasks as the ISU nodes. The RTM of the CLAprovides a hard disk for permanent data storage.

3.1.2 Signaling Node (ISU)

ISU handles H.248 signaling and signaling gateway functions. It also implements thecontrol interface towards the circuit-switched data server (CDS).

3.1.3 Media Processing Node (Transcoding Unit, TCU)

TCU performs traffic channel-related tasks on the user plane, such as RTP/RTCPprotocol termination, speech transcoding, and echo cancelling and speechenhancements. It also takes care of the MRF functions, such as tones,announcements and DTMF handling.

3.1.4 IP Network Interface Node (IPNI1/IPNI10)

IPNI1/IPNI10 terminates external IP over Ethernet user plane traffic and forwards theuser plane payload to TCU nodes for further processing. It provides either four

Gigabit Ethernet external interface, or one 10 Gigabit Ethernet external interface.

3.1.5 TDM Network Interface Unit (TDMSNI)

TDMSNI terminates external TDM over SDN traffic and transfers the payload to TCUfor further processing. It provides four external STM-1/OC-3 ports for TDM traffic.

Interface modules reside in an AMC Carrier blade.

3.1.6 Active Digital Distribution Frame (ADDF)

ADDF is a multiplexer device which provides PDH (E1/T1) connectivity. ADDF is fully

integrated into the operability solution of MGW. ADDF can be located as part ofMGW or located remotely to minimize cabling.

3.1.7 Internal Ethernet Switch (Hub)

Hub provides Ethernet connectivity inside MGW for internal control (Base Interfacewith 1G connection) and user plane (Fabric Interface with 10G connection) purposes.The Base Interface (BI) and Fabric Interface (FI) are completely independent internalnetworks. The RTM of the HUB contains central timing and synchronizationfunctions. The Hub and RTM are also used for inter-shelf connections and externalcontrol plane IP connections.


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3.2 Functional units in MGW based on IPA2800

Functionality is distributed to a set of functional units which can accomplish specialpurposes. These are entities of hardware and software, or only hardware. Units areconnected to the ATM-based switching matrix (SFU) either directly (in case of unitswith high traffic capacity) or via multiplexer unit MXU (in case of units with lowertraffic capacity).

The following figure illustrates functional units in MGW based on IPA2800.

Functional units in MGW based on IPA2800

Fig. 5 Functional units in MGW based on IPA2800

The functional units of the MGW fall into four categories according to their mainfunctions:

Management, control computer and data processing units

Switching and multiplexing units

Network element interface units

Units in timing, power distribution and hardware management subsystem


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3.2.1 Management, Control Computer, and Data ProcessingUnits

3.2.1.1 CACU, Control and Administrative Computer Unit

Purpose: The CACU controls the ATM switching fabrics and establishesconnections for calls. Its ATM switching management functions:

Establishment of both internal and external connections viathe SFU, including ATM circuit hunting and address analysis.

Management and control of the SFU, A2SU and MXU.

Transmission resource management.

Redundancy: 2N

Type: Computer unit

Plug-in Unit: CCP18-C Control Computer, Pentium M

Interfaces: ATM interface to MXU

Location: CAMA subracks 1-2, 1 unit per subrack

Control and Administrative Computer Unit (CACU)

Purpose: CACU controls the ATMswitch fabrics and establishesconnections for calls.

Its ATM switching managementfunctions comprises:

o Establishment of both internal andexternal connections via the SFU,including ATM circuit hunting andaddress analysis.

o Management and control of the SFU,A2SU, and MXU

o Transmission resource managementRedundancy: 2N

PIU:CCP18-C (Intel Pentium M)

Interface:ATM interface to MXU

Max. number of units insubracks:2 CCP18-C

Fig. 6 CACU


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3.2.1.2 CM, Central Memory

Purpose: The CM serves as the central data storage and distribution facility in

the exchange. It also handles the centralized part of the commonchannel signaling, for example, digit analysis.

Redundancy: 2N

Type: Computer unit

Plug-in Unit: CCP18-C Control Computer, Pentium M



Central Memory (CM)

Purpose: CM serves as the centraldata storage and distribution facility.

It also handles the centralised part ofthe common channel signalling, for

example, digit analysis.Redundancy: 2N



Max. number of units insubracks:2

CCP18-C

Fig. 7 CM


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3.2.1.3 ISU, Interface Control and Signaling Unit

Purpose: The ISU is responsible for signaling gateway functions between

access networks and MSC Server. Its tasks include the following:

Processing of the Message Transfer Part (MTP) and SignalingConnection Part (SCCP) of both narrowband and wideband SS7signaling

All message handling and processing functions related to thesignaling channels connected to it.

Redundancy: N+1

Type: Computer unit with no sub-units

Plug-in Unit: CCP18-CControl Computer, Pentium M


Location: CAMA subracks 3-4, all CAMB and CAMC subracks: 1 unit persubrack

Interface Control and Signaling Unit (ISU)

Purpose: ISU is responsible forsignalling gateway functionsbetween access networks and MSCServer.

Its task include the following:

o Process MTP and SCCP of bothnarrowband and wideband SS7signalling.

o Messange handling and processingfunctions related to the signallingchannel connected to it.

Redundancy: N+1



Max. number of units insubracks:18 (New deliveries inMGW U5.0) CCP18-C

Fig. 8 ISU


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3.2.1.4 VANU, Voice Announcement Unit

Purpose: The Voice Announcement Unit (VANU) controls the announcement

function of MGW. It stores the individual speech samples, constructscomplete announcements from them and sends them to the DSPunits for further processing.

Redundancy: None or load sharing

Type: Computer unit

Plug-in Unit: CCP18-CControl Computer, Pentium M



Voice Announcement Unit (VANU)

Purpose: VANU controls theannouncement function of MGW.

It stores the individual speechsamples, constructs completeannouncements from them andsends them to the DSP units forfurther processing.

Redundancy: None




CCP18-C

Fig. 9 VANU


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3.2.1.5 SWU, Switching Unit

Purpose: The SWU is a LAN/Ethernet switching function, which provides

LAN/Ethernet interface for control plane (H.248 and M3UA) andO&M signaling (e.g. towards NetAct). ESA40-A has four GigabitEthernet ports. One pair of ESA40-A can provide four protected GbEthernet ports. This allows the separation of control plane and O&Mtraffic to dedicated ports within one pair. ESA40-A supports L3connectivity solution.

Redundancy: SN+

Type: Ethernet switch

Plug-in Unit: ESA40-A

Interfaces: LAN/Ethernet to OMU, ISU and site LAN

Location: 1 unit in CAMA subracks 1-4

Switching Unit (SWU)

Purpose: SWU is a LAN/EthernetSwitching function, which providesLAN/Ethernet interfaces for:

o Control plane (H.248 and M3UA)

o O&M signalling (e.g. towards NetAct)

ESA40-A has four Gb Ethernet ports.

This allows the separation of controlplane and O&M traffic to dedicatedports within one pair.

ESA40-A supports L3 connectivitysolution.

Redundancy: SN+PIU:ESA40-A (LAN/Ethernet switch)

Interface: LAN/Ethernet to OMU,ISU and site LAN

Max. number of units in subracks:6

ESA40-A

Fig. 10 SWU


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3.2.1.6 OMU, Operation and Maintenance and its subunits

Purpose: The OMU handles all the MGW's crucial upper-level system

maintenance functions, such as hardware configurationmanagement, Hardware Management System (HMS) supervisionand the associated centralized recovery functions. In the event of afault, the OMU automatically activates appropriate recovery anddiagnostics procedures within the MGW. It also serves as aninterface between the NEMU and the other units of the exchange.The OMU has dedicated storage devices, which house the entiresystem software and the event buffer for intermediate storing ofalarms, along with the radio network configuration files.

Storagedevices

2 WDU, mirrored hard disk

1 FDU, USB memory stick

Redundancy: 2N

Type: Computer unit, with a dedicated storage device unit as a sub-unit.

Plug-in Unit: CCP18-A Control Computer, Pentium M

Interfaces: ATM virtual channels to MXULAN/Ethernet via ESA24 to NEMUDuplicated Small Computer Systems Interface (SCSI)Service Terminal interfaceMultiplexer Interface

Duplicated Hardware Management System (HMS) interfaceLocation: CAMA subracks 1-2, 1 unit per subrack


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OMU's Storage Device

Purpose: The OMU has two dedicated hard disk units which serve as aredundant storage for the entire system software, the event buffer

for intermediate storing of alarms, and the radio networkconfiguration files.Backup copies are made onto a USB memory stick that can beconnected to the CCP18-A plug-in unit's front plate.Only memory sticks can be used.FDU is the functional unit whenusing the USB memory stick. No separate configuration in the HWdatabase is needed, because the USB memory stick is an externaldevice. When removing the USB memory stick, set the state toblocked, because the system does not do it automatically.

Redundancy: 2N (HDS-B)

Type: Sub-unit to OMU

Plug-in Unit: HDS-B: Hard Disk Drive with SCSI Interface

Interfaces: Small Computer System Interface (SCSI)



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Operation and Maintenance Unit (OMU)

Purpose: OMU handles all theMGWs crucial upper-layer systemmaintenance functions, such as:

o Hardware configuration management

o Hardware Management System(HMS) supervision

o Associated centralised recoveryfunctions.

In the event of fault, the OMUautomatically activates appropriaterecovery and diagnostics procedureswithin the MGW.

Redundancy: 2N

PIU:CCP18-A (Intel Pentium M)

Interface:ATM interface to MXU,LAN/Ethernet via ESA40-A,Duplicated SCSI, Service Terminalinterface, Duplicated HMS interface


CCP18-A

Fig. 11 OMU

OMUs storage devices

Purpose: OMU has two dedicatedhard disk units which serve as aredundant storage for:

o The entire system software

o The event buffer for intermediatestoring of alarms

o The radio network configuration files.

Backup copies are made onto aUSB memory stick that can beconnected to the CCP18-A PIUsfront plate.

Redundancy: 2N

PIU:HDS-B

Interface: SCSI (Small ComputerSystem Interface)


HDS-B

Fig. 12 OMUs WDU


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3.2.1.7 TCU, Transcoding Unit

Purpose: The TCU includes a number of signal processors whose main

functions are: transcoding, that is, speech signal conversion between the codedformat used in the WCDMA Radio Access Network and the PCMformat used in the GSM network.

signal level control

discontinuous transmission

All DSPs of the unit can be freely allocated within the MGW.

Redundancy: SN+

Type: Signal processing unit with no sub-units

Plug-in Unit: CDSP-D

Configurable Dynamic Signal Processing Platform


Location: Max. 12 units each in CAMA subracks 3-4, all CAMB and CAMCsubracks

Transcoding Unit (TCU)

Purpose: TCU includes a numberof signal processors whose mainfunctions are:

o Transcoding

o Signal level control

o Discontinuous transmission

All DSPs of the unit can be freelyallocated within the MGW.

Redundancy: SN+

PIU:CDSP-DT



CDSP-DT

Fig. 13 TCU


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3.2.2 Network Element Interface Units

Since MGW can be used in both 2G and 3G environment, it provides flexible

alternatives for both TDM- and packet-based interfaces. MGW provides thepossibility to combine both ATM and IP interfaces in one element according tonetwork demands. All interface types can be scaled independently, thus making itpossible to have only those interfaces which are required in each element.

Network Interfaces

SFU

MGW

2*1GB

IP Backbone

SFU

RNC/MGW

RNC/MGW

SDH/Sonet

NPGEP

ATM (AAL2) forUserplane

NPS1(P) (PIU:NP8S1)

8*STM-1/OC-3

interfaces

SDH/Sonet

PSTNBSSIWFMSS

n*E1/T1via ADM

PSTNMSS,BSSIWF

PSTN

BSS

RNC

IWSEPM

X

U

NPS1(P)

NIWU

PSTN/A/IWF/Ater Interface

IWSEP/IWSTP (PIU:IW8S1-

A)

8xSTM-1 interfaces

NIWU (PIU: IW16P1A)

16*E1/T1/JT1 TDM interface

IP for Userplane

NPGEP (PIU:NP2GE)

2x1GB Electrial orOptical Ethernet

Fig. 14 Multimedia Gateway Network Interfaces


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3.2.2.1 NPGEP, Network Interface Unit

Purpose: Maps IP packets to and from Ethernet frame structure including

packet classification, forwarding, scheduling, and trafficmanagement.

Redundancy: 2N

Type: IP Interface unit

Plug-in Unit: NP2GE

Interfaces: 2 x 1000Base-T Ethernet electrical2 x 1000Base-LX Ethernet optical

Location: 1 units in all CAMA, CAMB and CAMC subracks

Network Interface Unit (NPGEP)

Purpose: NPGEP provides2x1000Base-T Ethernet electricaland 2x1000Base-LX/-SX Ethernetoptical interfaces supporting bothsingle-mode and multi-mode fibersand the means to execute physicaland IP layer functionality.

It maps packets to and fromEthernet frame structure including

o Packet classification, forwarding andscheduling

o Traffic management

Redundancy: 2N

PIU:NP2GE-A

Interface: 2x1000Base-T Ethernetelectrical, 2x1000Base-LX/-SXEthernet optical


NP2GE-A

Fig. 15 NPGEP


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3.2.2.2 NPS1/NPS1P, Network Interface Unit STM-1

Purpose: Provides SDH STM-1 interfaces and handles bit timing, linecoding, and timing recovery. Typically used in connectionsbetween the MGW and the RNC.

Redundancy: NPS1: NoneNPS1P: 2N

Type: Networking Interface unit

Plug-in Unit: NP8S1Network Interface 8 x 155.52 Mbit/s STM-1

Capacity/performance: Eight optical STM-1/OC-3 interfaces, 155.52 Mbit/s each. Thepayload capacity of one STM-1/OC-3 interface is 150.336 Mbit/s.The STM interfaces are compliant with the ITU-T G.783specifications; the OC interfaces with the ANSI T1.105specifications.While the NP8S1 plug-in unit also provisions for two STM-4/OC-12 interfaces (each with 622.08 Mbit/s total capacities and601.344 Mbit/s payload capacities), STM-4/OC-12 interfaces arenot currently supported in MGW and RNC.

Interfaces: ATM interface to SFUClock reference output to TSS3

Location: NPS1P: 2 units in CAMA subrack 3-4, all CAMB and CAMCsubracks

NPS1: 1 unit in CAMA subrack 3-4, all CAMB and CAMCsubracks


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Network Interface Unit STM-1 (NPS1/NPS1P)Purpose: NPS1(P) provides SDH

STM-1 interfaces and handles bittiming, line coding, and timingrecovery.

Redundancy: 2N

PIU:NP8S1-A

Capacity:Eight optical STM-1/OC-3interfaces, 155.52 Mbit/s each.

Interface:ATM interface to SFU,

Clock reference output to TSS3-AMax. number of units in

subracks:7NPS1(14NPS1P)

NPS1P/NPS1

Fig. 16 NPS1/ NPS1P


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3.2.2.3 IWSEP/IWSTP, Network Interface Unit STM-1/OC-3

Purpose: IWSEP/IWSTP provides STM-1/OC-3 interfaces. The main

tasks are:Implements the TDM over SDH channel bit stream conversion tothe AAL1 ATM channel cell stream to be forwarded to SFU andvice versa.

Support Ater interface.

Support up to 128 timeslots for SS7 signaling.

Redundancy: 2N

Type: Signal processing unit

Plug-in Unit: NI16P1A

ATM Network Interface 16 x PDH E1/T1/JT1

Capacity/performance:

Sixteen physical PDH electrical interfaces, each with abandwidth of:

2048 Kbit/s (E1) or 1544 Kbit/s (T1/JT1)

Interfaces: ATM interface to MXUClock reference output to TSS3

Location: 3 units in CAMA subrack 3-4 and all CAMB and CAMC subracks


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Network Interface Unit STM-1/OC-3 (IWSEP/IWSTP)

Purpose: IWSEP/IWSTP providesSTM-1/OC-3 interfaces.

The main tasks are as follows:

o Implements the TDM over SDHchannel bit stream conversion to the

AAL1 ATM channel cell stream to beforwarded to SFU and vice versa.

o Support Ater interface.

o Support up to 128 timeslots for SS7signalling.

Redundancy: 2NPIU:IW8S1-A

Capacity:Eight optical STM-1interfaces

Interface:ATM interface to SFU,RS232, Clock reference output toTSS3-A


IWSEP/IWSET

Fig. 17 ISWEP/IWSTP


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3.2.2.4 NIWU, Network Interface Unit TDM

Purpose: The ATM network interface unit IW16P1A contains TDM

E1/T1/JT1 interfaces, which carry traffic at the A interface,between the MGW and the MSC. IW16P1A also provides supportfor the Ater interface towards the BSC, eliminating the need for aseparate transcoder between the MGW and BSC.The unit also performs the user plane conversion between theTDM format and the ATM format

Redundancy: None

Type: Network Interface unit

Plug-in Unit: IW16P1AInterworking Unit 16 x E1/T1/J1


Sixteen physical TDM electrical interfaces, each with a bandwidthof:

2048 Kbit/s (E1) or 1544 Kbit/s (T1/JT1)

Interfaces: ATM interface to MXURS232Clock reference output to TSS3

Location: 6 units in CAMA subrack 3-4 and in all CAMB, CAMC subracks


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Network Interface Unit TDM (NIWU)

Purpose: IW16P1A containsE1/T1/JT1 interfaces for TDMsignalling and user plane.

The unit also performs the userplane conversation between theTDM format and the ATM format.

Redundancy: None

PIU:IW16P1A

Capacity:16 physical TDM

electrical interfacesInterface:ATM interface to SFU,

RS232, Clock reference output toTSS3-A

Max. number of units in subracks:30/60/90

IW16P1A

Fig. 18 NIWU


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3.3 Switching and Multiplexing Units

Switching and multiplexing in the MGW is based on the Asynchronous Transfer Mode(ATM) technology with full support to the various traffic types used in the network.The units in this category are the following:

ATM Switching Fabric Units (SFUs) which are used for switching the callsprocessed by the exchange

Multiplexer Units (MXUs), for connecting the low-bit-rate network interface units,along with the computer units and signal processing units (which typically havesmall to moderate bandwidth requirements) to the ATM switch fabric

AAL 2 Switching Units (A2SUs), which ensure efficient transport of informationwith limited transfer delay for low-to-moderate bit-rate units, connected to the main

switch fabric.In addition, the units in this block provide the ATM interface which serve as the mainmessage bus between the units in the exchange. Upper-level control functions for allthree units are performed by the CACU functional unit.


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ATM Connections to SFU

Switching and multiplixing in MGW isbased on the ATM technology.

The units are:

o SFUs which are used for switching thecall processed by MGW

o MXUs for connecting the low-bit-ratenetwork interface units to the SFUs.

Allocation of the MGWs ATMconnection: 2.5 Gbit/s serial switchingfabric port interface (SFPIF2G5):

o 32 ports of 3.9 Mcells/s ATM cell rate(or 1.65 Gbit/s user data rate)

o One input or output port consists of oneserial data line of 2.5 Gbit/s

o Ports can be conbined for higher datarates

o Duplication needs its own fabric port

o The maximum cable length is 5 m

HubSFU

MXU

MXU

MXU

MXU

CMCM

1-22pcs

CMCACU

2pcs

CMOMU

2pcs

FDU WDUWDU

CMISU

1-8 pcs

CMIWSEP/IWSTP

0-14 pcs

CMNPS1/NPS1P

0-14 pcs

CMNPGEP

0-16 pcs

CMA2SU

(used in release

prior to U5.0 only)

0-1 pcs

CMTCU

0-9 pcs

CMNIWU

0-9 pcs

CMISU

1-2 pcs

TBU

EHU

3-11

TBU

Fig. 19 ATM connections to SFU

The SFU switching fabric has 32 ports for connections to the other units in theexchange, with an aggregate capacity of 20 Gbit/s (equivalent to 64 STM-1 lines);each port, in turn, has a capacity of 1.65 Gbit/s. The connections through the portsare allocated in the following manner:

Some ports are used for the external high-bit-rate connections provided byNPS1/NPS1P & NPGEP.

The other ports are used for connections to the low-bit-rate network interface unitsand the computer units via the mutually redundant MXU pairs. One MXU pairrequires one port.

The equipment of the MGW is organized as groups of units around its MXU pairs,with each group connecting to a MXU pair of its own. Normally, one such groupoccupies one subrack, with the exception of the equipment connecting to the firstMXU pair, which requires two subracks' space (CAMA subracks 1 and 2).


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3.3.1 SFU, Switching Fabric Unit

Purpose: The ATM Switching Fabric Unit (SFU) provides part of the ATMcell switching function. It provides 2N redundancy, full accessibility,and is non-blocking at ATM connection level, that is, if the inputand output capacities are available, the connection can beestablished. The ATM Switching Fabric supports point-to-point andpoint-to-multipoint connection topologies, as well as differentiatedhandling of various ATM service categories. High capacity networkinterface units and ATM Multiplexer units are connected to theredundant SFU.

Redundancy: 2N

Type: Switch Fabric unit

Plug-in Unit: SF20H


20 Gbit/s

Interfaces: ATM interfaces: Switch fabric interfaces for NP8S1 network interfaces Multiplexer interfaces from SFU's unit computer to OMU

(via MXUs) OMU from the unit computer of the SFU (for OAM

purposes and software uploads, via MXUs)

Location: One unit in each of CAMA subracks 1-2


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Switching Fabric Unit (SFU)

Purpose: SFU provides part of theATM cell switching function.

It provides full accessibility and isnon-blocking at ATM connectionlevel.

SFU supports point-to-point andpoint-to-multipoint connectiontopologies, as well as,differentiated handling of variousATM service categories.

Redundancy: 2NPIU:SF20H, SF10E (only for

upgrades)

Capacity:2.5 Gbits/s

Interface:ATM interface

Max. number of units in subracks:2 SF20H

Fig. 20 SFU


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3.3.2 MXU, Multiplexer Unit

Purpose: The ATM Multiplexer (MXU) multiplexes traffic tributary unitstowards the switching fabric thus enabling the efficient use ofswitching resources for low bit rate network interface units andcomputer units with small to moderate bandwidth requirements.The ATM Multiplexer also includes part of the ATM layerprocessing functionality, such as policing, statistics, OAM, buffermanagement, and scheduling. Control computers, signalprocessing units and low bit rate network interface units areconnected to the ATM Switching Fabric via the MXU, which is a 2Nredundant unit.

Redundancy: 2N

Type: ATM switching unit, subunit of SFU

Plug-in Unit: MX1G6


1.6 Gbit/s

Interfaces: ATM interfaces to: SFU switching block SFU unit computer control computer units network interfaces TCU and A2SU connection between the passive MXU via the active one to

OMU (for OAM purposes)

Location: CAMA, CAMB, CAMC subracks: 2 units per subrack


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Multiplexer Unit (MXU)

Purpose: MXU multiplexes traffictributary units towards SFU.

It includes part of the AMT layerfunctionality, such as:

o Policing

o Statistics

o OAM

o Buffer management

o Scheduling

Redundancy: 2NPIU:MX1G6-A

Capacity:1.6 Gbits/s

Interface:ATM interfaces


SF20H

Fig. 21 MXU


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3.3.3 Timing, Power Distribution and HW ManagementSubsystem

The timing, power supply and hardware management subsystems form the lowestlevel in the computing hierarchy of the IPA2800 network elements. Each subsystemis composed of a redundant master unit and a duplicated data distribution/collectionbus. In each case, the bus actually extends through some lower level units to virtuallyall of the exchange's plug-in units, which are equipped with dedicated hardwareblocks supporting the core parts of the subsystem.

The network element's clock distribution and Hardware Management subsystems(TBU) use the same two types of plug-in units, namely:

TSS3, Timing and Synchronization, SDH Stratum 3

TBUF, Timing Buffer.

The clock system meets Stratum 3 level accuracy requirement, as defined in BellcoreTA-NWT-1244 standard.

The Power Distribution Subsystem in the exchange uses two types of plug-in units,namely:

PD30, Power Distribution Plug-in Unit 30 A

CPD120-A, Cabinet Power Distributor 120 A.


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3.3.3.1 TBU, Timing and Hardware Management Bus Unit

3.3.3.1.1 TSS3, Timing and Synchronization, SDH Stratum 3

Purpose: The TSS3s generate the clock signals necessary for synchronizingthe functions of the MGW. Normally, the TSS3 operates in asynchronous mode, that is, it receives an input timing referencesignal from an upper level of the network and adjusts its localoscillator to the long time mean value by filtering jitter and wanderfrom the timing signal. It transmits the reference to the plug-in unitsin the same subrack (all plug-in units are equipped with onboardPLL blocks), as well as to the TBUF units, which distribute thesignals to units not directly fed by the TSS3s. The TSS3 has inputsfor both synchronization references from other network elements

(via the network interfaces) and for those from external sources(options are 2,048 Kbit/s, 2048 MHz or 1.54 MHz)If all synchronization references are lost, the TSS3 can operate inplesiochronous mode, that is, by generating independently thesynchronization reference for the units in the exchange.The TSS3s are also involved in the functioning of the HMS bus.They collect the alarms from the PIUS in the same subrack andtransfer them further to the HMS master net, which brings thealarms to the appropriate OMU.

Redundancy: 2N

Type: Functional unit with TBUF units as sub-units

Plug-in Unit: TSS3Timing and Synchronization, SDH Stratum 3

Interfaces: Synchronization reference interfaces:three line inputs (from STM-1 or TDM lines)two external inputs (2,048 Kbit/s, 2048 MHz, 1.54 MHzeight outputs to cabinet timing busesone output to subrack timing busAlarm interfaces:one input from PIUs in same subrackone output to OMU via HMS Master Net

Location: One unit in each of CAMA subracks 1-2


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3.3.3.1.2 TBUF, Timing Buffer

Purpose: The TBUF unit is a clock buffer which distributes the synchronizationsignals generated by the TSS3s to plug-in units not directly fed bythe TSS3s.Like the TSS3s, the TBUFs are also involved in the functioning ofthe HMS bus. They collect the alarms from the PIUS in the samesubrack and transfer them further to the HMS master net, whichbrings the alarms to the appropriate OMU.

Redundancy: 2N

Type: Functional unit, sub-unit of the TSS3

Plug-in Unit: TBUF

Timing Buffer

Interfaces: Synchronization reference interfaces:

one input from TSS3 or another TBUF

one output to subrack timing bus

one output to another TBUFAlarm interfaces:

one input from PIUs in same subrack

one output to OMU via HMS Master Net

Location: One unit in each of CAMA subracks 1-2;Two units in all other CAMA, CAMB and CAMC subracks.


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Timing and Synchronization, SDH Stratum 3 (TSS3) &

Timing Buffer (TBUF)

TSS3 TBUF

Fig. 22 TBU


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3.3.3.2 Connection principle and redundancy for the timing andsynchronization distribution bus routing

The MGW has two separate timing and synchronization distribution buses to ensure2N redundancy for the internal timing signal distribution. Each bus has its ownsystem clock (a TSS3 plug-in unit), distribution cabling and timing buffers (TBUFplug-in units).

The two TSS3 units backing each other up are placed in different subracks (subracks1 and 2), each of which is powered by a power supply plug-in unit of its own toensure redundancy for the power supply. Each of these subracks is also equippedwith a TBUF plug-in unit, which connects the equipment in the subrack to the otherclock distribution bus. The CAMA subracks 3 and 4 and all CAMB subracks, on theother hand, have all two separate TBUF units which connect to different clockdistribution buses by means of cables of their own.

The clock distribution principle in the exchange is shown in the figure below.

Clock BUS

Fig. 23 Routing of the duplicated clock distribution bus


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3.3.3.3 HMS subsystem

The hardware management subsystem has three hierarchically organized layers of

equipment. The highest level in the hierarchy is formed by the HardwareManagement Master Nodes (HMMNs), one in each OMU, which control the wholesubsystem. The TSS3s and TBUFs in the subracks have separate HardwareManagement System Bridge nodes (HMSBs), which form the next, intermediate levelin the hierarchy. As the name suggests, they serve as bridges which connectHMMNs to the lowest-level blocks in the hierarchy, Hardware Management SystemSlave Nodes (HMSSs). Implemented as dedicated hardware blocks in all plug-inunits, the latter are independent from the other blocks of the plug-in unit, for example,in terms of the power supply.

A block diagram which illustrates the HMS subsystem implementation is shown in thefigure below.

Hardware Management Subsystem (HMS)

Purpose: HMS has 3 hierarchically organised layers of equipment.

o Hardware Management Master Nodes (HMMNs)

Uppest level in the hierarchy

Control the whole subsystem

Located in OMU

o Hardware Management System Bridge Nodes (HMSBs)

Intermediate level in the hierarchy

Serve as bridges which connect HMMNs to the lowest-level block in thehierarchy

Located in TBU (TSS3s and TBUFs)

o Hardware Management System Slave Nodes (HMSSs)

Locate in every PIUs

Redundancy: 2N

Fig. 24 HMS


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The MGW has also two mutually redundant hardware management buses, which areimplemented by means of the same plug-in units as the timing and synchronizationbuses, that is, the TSS3s and the TBUFs. The routing of the hardware management

buses, however, differs somewhat from that of the timing and synchronization buses.The Hardware Management Bus is organized in such a way that the TSS3s andTBUFs are on an equal level of the subsystem; both act as parallel HMS bridgeswhich connect the plug-in units in the same subrack to the HMS master net, whichbrings the alarms to the appropriate OMU.

HMS

System

Fig. 25 Block diagram of the HMS subsystem


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HMS BUS

Fig. 26 Routing of the duplicated HMS bus


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3.3.3.4 Power Distribution Subsystem

Purpose: The Power Distribution Subsystem distributes the -48V power fromthe rectifiers or batteries to the equipment inside the MGW cabinets.This subsystem consists of two CPD120-A power distribution panelsat the top of each cabinet, one PD30 power distribution plug-in unitin each subrack and the associated cabling. See the Cable Lists fora visual representation of the power feed to each subrack.The PD30 unit also controls the cooling equipment of its ownsubrack on the basis of messages sent by the OMU.

Redundancy: Power distribution subsystem is duplicated by providing twoindependent feeding input branches from cabinet level to plug-in unitlevel.

Type: Subsystem

Plug-in Unit: CPD120-ACabinet Power Distributor 120 APD30Power Distribution Plug-in Unit 30 A

Interfaces: One input for each of the two CPD120-AsFour outputs to subracks in CPD120-AOutputs to four groups of plug-in units (in PD30)Fan tray control and alarm interface

Location: Either one CPD120-A unit or CPD120-A units at the top of eachcabinet; one PD30 plug-in unit in each subrack


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Power Distribution Subsystem

PD30

Fig. 27 Power distribution system


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3.3.4 EHU, External Hardware Alarm Unit

Purpose: The purpose of External Hardware Alarm Unit is to receive externalalarms and send indications of them as messages to OMU-locatedexternal alarm handler via HMS.A second function is to drive the optional External Hardware Alarmpanel (EXAU-A / EXAU), the cabinet integrated lamp, and CAINDalarm indicator located on the top of CAMA cabinet and possibleother external equipment.

Redundancy: None

Type: Functional Unit

Plug-in Unit: EHATExternal Hardware Alarm Terminal

Interfaces:

Interfaces include 32 voltage controlled inputs, 8 current controlledinputs, 16 general purpose 20 mA current outputs. Connections toexternal devices via cabling panel 1 located in the rear of the CAMAcabinet.

Location: One unit per network element, in CAMA subrack 2,3


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External Hardware Alarm Unit ( EHU)

Purpose: EHU receive external alarmsand send indications of them asmessages to OMU-located externalalarm handler via HMS.

A second function is to drive:

o the optional External Hardware Alarmpanel (EXAU-A)

o the cabinet integrated lamp

o CAIND alarm indicator located on top ofCAMA cabinet and possible other externalequipment.

Redundancy: None

PIU:EHAT

Interface: 32 voltage controlled inputs,8 current controlled inputs, 16 generalpurpose 20 mA current outputs.Connections to external devices viacabling panal1 in the rear of CAMA. SF20H

Fig. 28 EHU

3.3.4.1 EXAU, External hardware alarm panel

The optional peripheral EXAU provides a visual alarm of the fault indications of theMGW. The EXAU panel is located in the telecommunications site rooms, outside thenetwork element.

3.3.4.2 CAIND, Cabinet alarm indicator

The CAIND is located on the top of CAMA cabinet and provides a visual alarm

indicating the network element with a fault.


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4 MGW Hardware Configuration


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The mechanical construction of the IPA2800 network elements is based on M2000mechanics platform. The equipment is housed in IC186 or IC186-B cabinets. Onecabinet has space for the cabinet-specific power distribution equipment, four

subracks and subrack-specific cooling equipment.All IPA2800 network elements use three types of subracks, called SRA1-A, SRA2-Aand SRBI-B. The SRA1-A is only used in the first two positions in the A cabinet, allother positions use the SRA2-A. The only difference between SRA1-A and SRA2-Asubracks is that the SRA2-A integrates more of the subrack's internal cabling, suchas signals from the MXUs to tributary units, into its back panel. SRBI-B is equippedbehind the SRA1-A and SRA2-A subracks to provide modular backplaneconnections.

The plug-in units are generally connected to the other parts of the system by meansof backplane connectors. Some of the connections, however, are made from the frontpanels, normally by means of standard RJ-45 connectors. The plug-in units of theIPA2800 network elements are designed to support hot swapping. The plug-in-unitsare equipped with various LED indicators for monitoring the unit's condition.

The MGW have three different equipment cabinets, namely:

Cabinet Module A (CAMA)

Cabinet Module B (CAMB)

Cabinet Module C (CAMC)

The subracks are assigned with numbers starting from 1 at the top of each cabinet

and ending to 4 at its bottom. The following figure shows all the equipment cabinetsand cabling cabinets in the MGW.

The configurations of the MGW support left-to-right or alternatively right-to-leftcabinet installation as shown by the figure below. The cabinets must always beinstalled into a single row.


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Base Module

Expansion

Module

MGW Cabinets and Subracks

Fig. 29 MGW cabinets and subracks

MGW Configuration

Fig. 30 MGW cabinet installation (U4.0)


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All the MGW configurations have the CAMA cabinet. First two subracks in the CAMAcabinet (the base module) are the same for all configurations. All other subracks areequipped according to the configuration and capacity needed, the main difference

between the configurations being the number of TCU/A2SU units as well as type andnumber of interface units.

The minimum configuration of the MGW features only the CAMA cabinet wheresubracks 1-2 are fully equipped and subracks 3-4 are partially equipped. TBU andPD30 units are always equipped to empty subracks in all three cabinets.

For expansion, the MGW provides roughly two kinds of capacities that can beincreased: interface capacity and user plane processing (DSP) capacity. Expandedcapabilities can be obtained by adding new cabinets and the necessary plug-in unitsin the empty subracks according to the chosen configuration. The processingcapacity of the MGW is increased by adding TCUs, ISUs and MXUs. The interfacecapacity is then added independently by adding NIWU, NIP1, NPS1P/NPS1, NPGEPand IWS1E/IWS1T units.

CAMA Subrack 1 (Base Module)

Fig. 31 CAMA subrack 1 (base module)


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Soc Classification level

1 Nokia Siemens Networks

CAMA Subrack 2 (Base Module)

Fig. 32 CAMA subrack 2 (base module)

In U4.0, there are three subrack configuration alternatives. The main differencebetween the subrack configurations is the number of TCU/A2SU units and numberand type of interface units.

Subrack configuration with IWS1E/T

Subrack configuration with NIWU/NIP1

Subrack configuration with TCU


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General principles

NIWU/NIP1 and IWS1E/T units cannot be equipped in the same subrack at the

same time NIP1 units are equipped before NIWU units.

ISUs cannot be equipped in a subrack without an MXU pair:

Units are equipped in index order

o The index order of TCU/A2SU units runs from subrack to subrack, topto bottom

o The index order of NIWU units runs in two sets: from slots 1-3 / subrackto subrack, top to bottom, from slots 4-6 / subrack to subrack, top tobottom

o The index order of IWS1E/T units runs in two sets: from slots 1-3 /subrack to subrack, top to bottom slot 4, subrack to subrack, top tobottom

o ISUs are equipped in index order starting from the lowest index, up tothe last subrack where MXUs are equipped additional ISUs areequipped in CAMA subrack 1-2


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MGW Expansion Modules

Three subrack configuration

alternatives

Subrack configuration

with IWS1E/T


with NIWU/NIP1


with TCU

Main difference between the

subrack configurations is the

number of TCU/A2SU units

and number and type of

interface units

Fig. 33 Equipment in CAMB subracks 14


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4.1 Hardware changes in release U5.0

The following new hardware products are introduced to the MGW in U5.0.New plug-in units:

High capacity TDM interworking unit, IW8S1-A. This plug-in unit requires theSF20Hswitching fabric unit.

ESA40-A Ethernet switch with 40 ports, for new deliveries and upgrades.

New variant of Timing and Synchronization plug-in unit, TSS3-A.

The following hardware products are removed from the MGW in U5.0.

Removed plug-in units:

MCPC2-A (NEMU) is removed after release upgrade.

MCP18(-B) (NEMU) is removed after release upgrade.

4.2 MGW release upgrade to U5.0

4.2.1 Software upgrade

All existing MGW elements (upgraded to latest U4.2 software level) can be upgradedto U5.0 software after the mandatory hardware upgrades have been performed. Ifonly software is upgraded to U5.0, the capacity of the MGW does not increase, butwith hardware extension, more capacity is gained. The software upgrade providesthe possibility to introduce new U5.0 functionalities.

4.2.2 Hardware upgrade

The mandatory hardware upgrade enables the U5.0 software upgrade and optionalhardware upgrades.For MGWs on U4 or U3C hardware level, there are no hardware requirements for theMGW upgrade to U5.0.If the MGW is initially on U1.5, U2 or U3A/B, some CPU upgrades might be needed(e.g. OMU CPU upgrade to CCP18-A). The ISU CPU memory requirement is 1024MB.

U5.0 offers optional hardware upgrade possibilities as listed below:

TDM/STM-1 interface units, IW1S1 and IW1S1-A, can be upgraded with IW8S1-A.The upgrade requires SF20H.

LAN switch unit upgrade: the ESA24 can be upgraded with ESA40.

IP user plane upgrade with SF10E and NPGEP (introduced in U4.2) is possiblealso in U5.0.

CDSP-DT usage with SF10 and SF10E.


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5 Phasing of features in MGW

Multimedia Gateway for both MSC Server and IP Multimedia Subsystem environmentis an evolution step from Multimedia Gateway belonging to 3G MSC. All featuresfrom previous releases and earlier architectures are also available in later releases.

Different functionalities become available in MGW as follows:

U2: Functionality required by both 3G MSC and the first release of MSC Serversystem.

U3A: STM-1/OC-3 interface for TDM use in MSC Server system.

U3B: Additional functionality for the MSC Server system release 2 includingpossibility to use the same network element also in IP Multimedia Subsystem.

U3C: Introduces Ater and Wideband AMR functionalities

U4: features for both the MSC Server environment and IP Multimedia Subsystemenvironment for the MSC Server system release 3

5.1 U5 Features

A over IP interface in MGW

Nokia Siemens Networks MSS system supports the 3GPP standard A interface,

Nokia Siemens Networks proprietary Ater interface in MGW, and 3GPP standardAoIP interface with TC in MGW at the same time. This support enables flexibleuse of both TDM and IP transmission, and a smooth upgrade from TDM A/Aterenvironment to AoIP when IP transmission is available and reliable enough. Thetranscoding resources implemented for TDM-based Ater in MGW can be utilizedwith AoIP.

AMR WB Adaptive Multi-Rate Wideband speech codec

AMR-WB is a wideband codec standardized by 3GPP, and supports 50-7000 Hzaudio frequency with 16 kHz sampling compared to 200-3400 Hz and 8 kHz usedin narrowband codecs. AMR-WB consists of nine speech codec modes with bitrates of 6.6, 8.85, 12.65, 14.25, 15.85, 18.25, 19.85, 23.05, and 23.85 kbit/s. Thelowest bit rate that provides excellent speech quality in a clean environment is12.65 kbit/s. Higher bit rates are useful for music and in conditions withbackground noise. Also lower bit rates of 6.60 and 8.85 kbit/s provide areasonable quality, especially compared to narrowband codecs.

AMR-WB can be used on the following MGW interfaces:

2G TDM A/Ater and AoIP with TC in MGW

3G Iu-CS

Mb/SIP IP access

Nb/IP backbone, and in MGW based on IPA2800 also ATM backbone


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Ater interface in MGW

Ater interface in MGW for 2G transcoding uses the same digital signal processing(DSP) resource pool as 3G transcoding, which means that there is no need to

allocate DSP resources for 2G and 3G transcoding separately.Since the transfer capacity of the Ater interface is up to four times greater thanthat of the A interface, implementing Ater Interface in MGW decreases the needfor TDM transmission capacity between BSC and MGW. This also means that asmaller number of the physical interfaces used for Ater (E1/T1 and STM-1/OC-3)are needed between MGW and BSC, as well as hardware providing TDMconnectivity in MGW.

Ater Interface in MGW supports the following voice and data services:

GSM transcoding (FR, HR, EFR, AMR, AMR WB codecs) and submultiplexing(16/32/64 kbit/s)

Speech enhancement features, such as Noise Suppression (NS), AcousticEcho Cancellation (AEC) and Automatic Level Control (ALC)

Tandem-Free Operation (TFO) for FR, HR, EFR, AMR, and AMR WB codecs

Special functions, such as Text Telephony (TTY)

Circuit pools 1, 3, 5, 7, 10, 13, 20, 21, 22, 23, 28, 32 and 37

Ater interface contains up to four A interfaces. Each A interface can belong to adifferent circuit pool, which defines the speech and data call capabilities of theconfigured circuits.For the Ater interface to function, the operator must configure the circuit pools in

the same way in all supporting network elements (MGW, MSS and BSC).

Embedded Interconnect Border Gateway Function

Nokia Siemens Networks offers a smooth transition with inherent IP peeringsolution, where Interconnect Border Gateway Function (I-BGF) is integrated intoMGW and Interconnect Border Control Function (I-BCF) is intergrated into MSCServer (MSS).Embedded I-BGF is a collection of features where MGW behaves as ademarcation point for media flows in order to fulfill security, regulatorycompliance, and quality of service (QoS) assurance requirements for real-timesession-based traffic. In the communications network Border Gateway Functionprovides the interfaces between IP transport domains. It resides at the boundarybetween two core networks.


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H.248 Load Balancing

This feature introduces two new H.248 concepts: Master ISU((M)ISU) means that the ISU contains one or several H.248

links. Slave ISU((S)ISU) means that the ISU DOES NOT contain any H.248 link. Master ISU can also be a Slave ISU from another Master ISUs

perspective.Unlike earlier releases wherein amount of virtual MGWs was related to number ofISUs, the number of virtual MGWs is significantly reduced from several vMGWper ISU to 4-6 per MGW depending on the SIGTRAN/SS7 configuration.The load can be shared equally between the ISU units. Load sharing can be doneeither by sharing the CPU capacity of the ISUs, or by sharing the amount of ISUcontexts whichever is the restricting factor in certain time in traffic profile. If ISUscontain also other signaling load than H.248, CPU capacity triggers the load

sharing.

IP-based Iu-CS Interface

The 3GPP Rel-5 enables the Iu-CS interface to use IP as a means of transport forthe user plane. This means that IP transports both user and control plane traffic inthe Iu-CS interface. IP-based Iu-CS Interface enables the network operator tohave an all-IP network architecture, in which IP is used for all the main interfacesbetween Universal Mobile Telecommunications System (UMTS) terrestrial radioaccess network (UTRAN) elements.

When using IP-based Iu-CS Interface, RANAP signaling can be transmitteddirectly between RNC and MSS instead of going through MGW. This decreasesthe signaling transport load in MGW, as only user plane traffic is carried betweenRNC and MGW.User plane traffic in IP-based Iu-CS Interface between RNC and MGW uses theReal-Time Transport Protocol (RTP) over User Datagram Protocol (UDP) toconvey traffic. The Real-Time Transport Control Protocol (RTCP) monitors theRTP stream and collects statistical data. The Iu-CS reference interface uses theIu user plane (UP) framing protocol.


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IP Connection Admission Control

IP CAC can be utilized at MGW level and IP-based route level. IP CAC at IPbased route level requires availability of the Multiple Isolated IP Networks feature

in MSS and MGW.IP CAC supports the following configurable parameters:

number of IP terminations at MGW level number of IP terminations at IP-based route level IP bandwidth at IP-based route level RTP packet loss at IP-based route level

The feature supports freely configurable warning and maximum levels for each IPCAC parameter. When a warning or maximum level is reached, MGWautomatically sets off an alarm. In case a maximum level is reached, MGW rejectsnew IP termination attempts from MSS until the IP CAC value decreases belowthe maximum level. If MGW rejects an IP termination attempt, MSS can reject the

call or make an alternative routing attempt through another IP-based route or userplane media such as TDM, if available.MSS supports IP CAC clear codes and statistics of call attempts rejected by IPCAC. MGW provides statistics of IP terminations, IP bandwidth, packet loss andthe number of IP termination requests rejected based on the IP CAC maximumlimit.

L3 Connectivity and Bidirectional Forwarding Detection in MGW

When L3 connectivity is used in MGW based on IPA2800, traffic of differentdomains (User Plane, Control Plane, O&M) goes through ESA40-A units. Number

of needed ESA40-A pairs (min1, max. 3) depends from the possible requirementsfor the physical separation and User Plane capacity.L3 connectivity can be implemented independently for each traffic domain.By using L3 connectivity, MGW can directly be connected with the IP/MPLSbackbone or Ethernet over SDH transmission networks.L3 connectivity provides DiffServ codepoint (DSCP) marking and jitter buffer toprovide quality management to the network.The multi-layer site switch or router should also support traffic classification andDSCP marking by using QoS access control lists. The signaling packets may beused for traffic prioritization.

Bidirectional Forwarding Detection (BFD) is a network protocol used to detectfaults between two forwarding engines.It provides low-overhead detection of faults even on physical media that don'tsupport failure detection of any kind, such as Ethernet, virtual circuits, tunnels andMPLS LSPs.BFD can be controlled by BFD software which is licensed to operate. It providesON/OFF function to control plane level.The destination and source IP addresses for the BFD sessions are configured inthe MGW's NPGEP IP interface cards.


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Multiple Isolated IP Networks

The Multiple Isolated IP Networks feature in the MSS system enables IP behaviorconfiguration according to logical IP interfaces in MGW (Nb/IP backbone, IP-

based Iu-CS, AoIP, Mb/SIP access). The traffic separation and configuration canalso be done within logical IP network reference numbers, for example, by usingdedicated IP-based routes with Nb/IP backbone towards each connected MGW.The traffic can also be separated with physical interfaces, for example, one forbackbone traffic, one for IP-based 3G and one for operator interconnection.The Isolated IP networks feature is controlled by MSC Server. It is possible toconfigure the used IP network reference identifier (IPnwR) into the user planedestination (UPD) of MSS Server. MSC Server indicates IPnwR in H.248termination resevation request.MGW uses the DSP parameter profile attached to IPnwR. The DSP parameterprofile includes QoS parameters, such as DSCP priority and jitter buffer size, and

speech enhancement parameters, such as Automatic Level Control (ALC),Acoustic Echo Cancellation (AEC) and Noise Suppression (NS).IP-based route level statistics are available according to additional features suchas IP CAC and measurements such as RTP/RTCP and jitter.

RAN Independent Multipoint A/Iu Support in MGW

The core network node selection and related NNSF in MGW enable MSS poolingwithout multipoint functionality support on the radio network. The NNSF in MGWselects the most suitable MSS node on the core network to serve the subscriber.This requires routing radio access network application part (RANAP) and base

station system application part (BSSAP) signaling through MGW.

The MGW analyzes the RANAP and BSSAP messages to the network resourceidentifier (NRI) value from the temporary mobile subscriber identity (TMSI) andanalyzes it to find out whether an MSS is dedicated for the transaction.If a valid NRI value cannot be identified in the TMSI (for example, when the userenters the pool area) the MGW uses the weighted round robin method withconfigurable weight factors to choose the suitable MSS.Once the pool area has been selected in the MSS, the MGW NNSF directs thesubsequent transactions (such as location updates, calls) to the same MSS byanalyzing the NRI.

As in the RAN node-based multipoint solution, the subscriber is served by thesame MSS as long as the subscriber stays in the pool area. This results inreduced signaling traffic.The MGW also uses the RANAP and BSSAP messages to verify that whether thepaging response is sent to the correct MSS for both TMSI and internationalmobile subscriber identity (IMSI) pagings. If a specific core network nodebecomes unavailable, MGW notices the situation.In general, the MGW acts towards MSSs in the way that is expected whensupporting the multipoint concept. Towards the radio network, MGW acts as if no

multipoint concept would be in use. To achieve sufficient core network resiliency,it is possible to route the signaling from one RAN node via a redundant MGW inan MGW cluster.


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The MGW cluster is a license-based configuration which is utilized in case BSC orRNC does not support quasi-associated signaling.In the configuration, multiple MGWs are defined with the same NNSF capability,

and they share a signaling point code (SPC). The other network elements do notneed configuration changes, as they do not see the cluster, but only the one SPC.

Real-Time User Plane Monitoring (Nelmon)

Nelmon is an external Linux-based server application designed to collect userplane quality monitoring data from one, or more, connected gateways. Nelmonimproves the existing MGW measurements by adding more granularity andenabling real-time monitoring by means of Traffica interface. For example, thecollected measurement data can be used for:

Evaluating traffic behavior in the MGW Troubleshooting certain traffic direction Monitoring the quality of external networks (radio, VoIP, IP-backbone)

Checking the measurement data of a single termination in case of acustomer complaint

One Nelmon server can be connected to ten U4.2-level MGWs with the totalconnection capacity of maximum of 120 000 simultaneous connections. Nelmoncollects user plane measurement data from each termination and calculates forthen MOS and RVALUE values.Processed user plane measurement data is delivered to NetAct Traffica. Trafficaserver displays network speech quality status in real-time.


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6 Glossary

2G 2nd Generation mobile phone network

3G 3rd Generation mobile phone network

3GPP Third Generation Partnership Project

AAL ATM Adaptation Layer

AEMF ATM Equipment Management Function

AMR Adaptive Multi-rate Speech Codec

ATM Asynchronous Transfer Mode

BSSAP Base Station Subsystem Application PartCACU Control and Administrative Computer Unit

CAMA Cabinet Module A

CAMB Cabinet Module B

CAMC Cabinet Module C

CM Central Memory

CMISE Common Management Information Service Element

CORBA Common Object Request Brokerage Architecture

CPS Connection Processing Server

CPU Central Processing Unit

CS Circuit Switched

DSP Digital Signal Processing

EDGE Enhanced Data Rates For GSM

FTP File Transfer Protocol

GCS Gateway Control Server

GERAN GSM/EDGE Radio Access NetworkGPRS General Packet Radio Service

GSM Global System For Mobile Communications

HMMN Hardware Management Master Node

HMS Hardware Management System

HMSB Hardware Management System Bridge node

HMSS Hardware Management System Slave Node

HSS Home Subscriber Server

IMA Inverse Multiplexing for ATM


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IMSI International Mobile Subscriber Identification

IN Intelligent Network

INAP Intelligent Network Application PartIP Internet Protocol

IP-NIU can be either IPFE/IPFEP, IPGE/IPGEP or IPGO/IPGOP

ISU Interface Control and Signaling Unit

IWS1 Network Interface Unit STM-1/OC-3

M3UA MTP3 User Adaptation

MAP Mobile Application Part

MGCF Media Gateway Control Function

MGW Multimedia Gateway

MMI Man Machine Interface

MML Man Machine Language

MSC Mobile Switching Centre

MSS MSC Server

MSSu Upgraded MSC Server

MTP Message Transfer Part

NEMU Network Element Management UnitNIP1 Network Interface Unit PDH

NIS1 Network Interface Unit STM-1

NIWU Network Interface Unit TDM

NPC Network Parameter Control ( used in NNI)

OAM Operations, Administrations and Maintenance

O&M Operation & Maintenance

OMU Operational And Maintenance Unit

PDH Plesiochronous Digital Hierarchy

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 ProtocolSCCP Signaling Connection Part


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SCSI Small Computer Systems Interface

SCTP Stream Control Transmission Protocol

SDH Synchronous Digital HierarchySIGTRAN Signaling Transport

SIP Session Initiated Protocol

SPMU Signal Processing Management Unit

SS7 Signaling System # 7

SVC Switched Virtual Connection

TBU Timing and Hardware Management Bus Unit

TBUF Timing Buffer

TMSI Temporary Mobile Subscriber Information

T-SGW Transport Signaling Gateway

TSS3 Timing and Synchronization, SDH Stratum 3

UE User Equipment

UMTS Universal Mobile Telecommunication System

UPC Usage Parameter Control ( used in UNI )

USB Universal Serial Bus

UTRAN UMTS Terrestrial Radio Access NetworkVANU Voice Announcement Unit

VC-3/ VC-4/VC12

Virtual Container , structural part of an STM-1 frame consisting ofpath overhead and a container

VMSS Visited MSC Server


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