introduction to telecom networks

NETWORK ARCHITECTURE OF GSM(GPRS/EDGE), WCDMA, LTE, ERICSSON CHARGING SYSTEM

INTRODUCTION TO TELECOM NETWORKS

© Ericsson AB 2014 | 2014-09-10 |

SS7 Fundamentals

Signaling PointsSSP = Service Switching Point, (e.g. MSC in mobile N/W)STP = Signal Transfer Point, Similar to IP router, Use to route point codesSCP = Service Control Point, Provides intelligence in the N/W (e.g. CCN)

Point Code = Unique identifier in MTP3 layer, Similar to an IP address.

GT (Global Title) = Unique identifier in SCCP layer, Unique identifier relating to application in use.

SS7 Protocol Stack Public Switched Telephone Network (PSTN)

MTP1 = Message Transfer Part 1MTP2 = Message Transfer Part 2MTP3 = Message Transfer Part 3SCCP = Signaling Connection Control PartTCAP = Transaction Capabilities Application PartMAP = Mobile Application PartINAP = Intelligent Network Application PartISUP = ISDN User Par

© Ericsson AB 2014 | 2014-09-10 |

Sigtran (SS7 Over IP)

Application

SCTP

Internet

Network Access

ISUP, MAP, CAP, INAP

TCAP

SCCP

MTP3 M3UA

MTP2

MTP1

SS7 Protocol Stack

Sigtran Protocol Stack

The SIGTRAN protocol stack includes the Stream Control Transmission Protocol (SCTP) and user adaptations SUA (SCCP user adaptation layer), M3UA (MTP3 user adaptation layer)

The SIGTRAN stack functions can be divided into SCTP stacks and protocol stacks for Adaptation Layers. SCTP is responsible for reliable signaling transport, streaming, congestion avoidance and control, bundling and un-bundling, multi-homing and association management, security and user-transparent fault management. SCTP stack supports various user adaptations including M3UA, M2UA, IUA, M2PA and SUA.

© Ericsson AB 2014 | 2014-09-10 |

Spectrum allocation for wireless technology

LTE

© Ericsson AB 2014 | 2014-09-10 |

IP NW

IP NW

IP NW

2G

3G

LTE

802.11 a

802.11 b

802.11 g

802.11 n

ADSLModem DSLAM

BRAS

ISP

BTSBSC GGSN

ISP

ISP

Access Point Access Point

Controller

User

User

User

Broadband N/W Connectivity

Mobile N/W Connectivity

WiFi N/W Connectivity

BNG

Popular methods to access internet

Node-BENode-B

Core N/WAccess N/W

RNC PGW

© Ericsson AB 2014 | 2014-09-10 |

BSS — Base Station System

BTS — Base Transceiver Station

BSC — Base Station Controller

MS — Mobile Station

NSS — Network Sub-System

MSC — Mobile-service Switching Controller

VLR — Visitor Location Register

HLR — Home Location Register

AuC — Authentication Server

GMSC — Gateway MSC

GSM 2G Architecture

SS7BTS

BSCMSC

VLR

HLRAuC

GMSC

BSS

PSTN

NSS

AE

CD

PSTNAbis

B

H

MS

GSM — Global System for Mobile communication

EIR

F

UmTRC

Ater

G-SMS

SMS-IWMSC

SMS-GMSC

SC

C

E

SMS — GMSC Gateway MSC

SMS — IWMSC InterWorking MSC

SC — Service Center

SME — Short Messaging Entity

© Ericsson AB 2014 | 2014-09-10 |

2G-BLOCK of MS

Mobile station (MS)In GSM, the mobile station consists of four main components:

Mobile Termination (MT) - offers common functions of a such as: radio Transmission and handover, speech encoding and decoding, Error detection and correction, signalling and access to the SIM. The IMEI code is attached to the MT. It is equivalent to the network termination of an ISDN access.

Terminal Equipment (TE) - is any device connected to the MS offering services to the user. It does not contain any functions specific to GSM.

Terminal adapter (TA) - Provides access to the MT as if it was an ISDN network termination with extended capabilities.

Subscriber Identity Module (SIM) - is a removable subscriber identification token storing the IMSI a unique key shared with the mobile network operator and other data.

© Ericsson AB 2014 | 2014-09-10 |

2G Block BSSBASE STATION SYSTEMThe Base Station System (BSS) is composed of two major components. These are:Base Station Controller (BSC) and Base Transceiver Station (BTS)

BSCThe Base Station Controller (BSC) is the central point of the BSS.The BSC can manage the entire radio

network and performs the following functions:• Handling of the mobile station connection and handover• Radio network management• Transcoding and rate adaptation• Traffic concentration• Transmission management of the BTSs• Remote control of the BTSs

BTSThe Base Transceiver Station (BTS) includes all radio and transmission interface equipment needed in

one cell.

TRCThe transcoder is responsible for Transco ding the voice channel coding between the coding used in

the mobile network, and the coding used by the world's terrestrial circuit-switched network, the Public Switched Telephone Network.

© Ericsson AB 2014 | 2014-09-10 |

2G BLOCK-NSS Mobile services Switching Center (MSC)

The MSC is responsible for routing voice calls and SMS as well as other services (such as conference calls, FAX and circuit switched data). The MSC sets up and releases the end-to-end connection, handles mobility and hand-over requirements during the call and takes care of charging and real time pre-paid account monitoring.

Visitor Location Register (VLR)The VLR is integrated with the MSC. This is referred to as the MSC/VLR. The VLR contains nonpermanent information about

the mobile subscribers visiting the MSC/VLR service area, for example, which location area the MS is currently in.

Gateway MSC (GMSC)The G-MSC is the MSC that determines which visited MSC the subscriber who is being called is currently located. It also

interfaces with the PSTN. All mobile to mobile calls and PSTN to mobile calls are routed through a G-MSC.

Home Location Register (HLR)In GSM, each operator has a database holding information about all subscribers belonging to the specific Public Land Mobile

Network (PLMN). This database can be implemented in one or more HLRs.

• Authentication Center (AUC)For security reasons, speech, data, and signaling are ciphered, and the subscription is authenticated at access. The AUC

provides authentication and encryption parameters required for subscriber verification and to ensure call confidentiality.

• Equipment Identity Register (EIR)In GSM, there is a distinction between subscription and mobile equipment. As mentioned above, the AUC checks the

subscription at access. The EIR checks the mobile equipment to prevent a stolen or non-type-approved MS from being used.

© Ericsson AB 2014 | 2014-09-10 |

GSM INTERFACE

Interface

Between Description

UmMS-BSS The air interface is used for exchanges between a MS and a BSS.

Abis BSC-BTS This is a BSS internal interface that links the BSC and a BTS. The Abis interface allows control of radio equipment and radio frequency allocation in the BTS.

Ater BSC-TRC This interface is a proprietary interface used between the BSC and TRC for control of the Transcoder resources and the A-interface circuits.

A BSC/TRC-MSC The A interface is between the BSS and the MSC. It manages the allocation of suitable radio resources to the MSs and mobility management. It uses the BSSAP protocols (BSSMAP and DTAP).

B MSC-VLR The B interface handles signaling between the MSC and the VLR. Whenever the MSC needs to access data regarding an MS that is located in its area, it interrogates the VLR using the MAP/B protocol over the B interface.

C GMSC-HLR or SMSG-HLR The C interface is between the HLR and a GMSC or a SMSC. Each call that originates outside of GSM (such as an MS terminating call from the PSTN) must go through a gateway to obtain the routing information that is required to complete the call, and the MAP/C protocol over the C interface is used for this purpose. Also, the MSC can optionally forward billing information to the HLR after call clearing.

D HLR-VLR The D interface is between the HLR and VLR, and uses the MAP/D protocol to exchange data related to the location of the MS and subsets of subscriber data.

E MSC-MSC The E interface connects MSCs. The E interface exchanges data that is related to handover between the anchor and relay MSCs using the MAP/E protocol. The E interface can also be used to connect the GMSC to an SMSC.

© Ericsson AB 2014 | 2014-09-10 |

GSM INTERFACE

Interface

Between Description

F MSC-EIR The F interface connects the MSC to the EIR and uses the MAP/F protocol to verify the status of the IMEI that the MSC has retrieved from the MS.

G VLR-VLR The G interface interconnects two VLRs of different MSCs and uses the MAP/G protocol to transfer subscriber information—for example, during a location update procedure.

H MSC-SMSG The H interface is located between the MSC and the SMSG and uses the MAP/H protocol to support the transfer of short messages.

I MSC-MS The I interface is the interface between the MSC and the MS. Messages exchanged over the I interface are transparently relayed through the BSS.

© Ericsson AB 2014 | 2014-09-10 |

GPRS System Architecture

GPRS requires new software and hardware in the BSC to implement PCU

PCU is responsible for GPRS packet data resources management, responsible for handling the MAC,RLC layer of radio interface and the network service layer of Gb interface ( Its is terminated in the PCU)

› PCU-Packet Control Unit

› SGSN ( Serving GPRS Support Node-this forms a gateway to the services within the network) it takes care of some important tasks, including routing, handover and IP address assignment. The SGSN has a logical connection to the GPRS device.

› GGSN ( Gateway GPRS Support Node-which forms the gateway to the outside world )is the “last port of call” in the GPRS network before a connection between an ISP or corporate network’s router occurs. The GGSN is basically a gateway, router and firewall rolled into one

© Ericsson AB 2014 | 2014-09-10 |

SS7BTS

BSC

MSCVLR

HLRAuC

GMSC

BSS

PSTN

NSS

AE

CD

PSTNAbis

B

H

MS




NSS — Network Sub-System






2.5G Architectural Detail

SGSN — Serving GPRS Support Node

GGSN — Gateway GPRS Support Node

GPRS — General Packet Radio Service

IP

2G+ MS (voice & data)

PSDNGi

SGSN

GrGb

Gs

GGSN

Gc

Gn

2G MS (voice only)

PCU

PLMN Gp

© Ericsson AB 2014 | 2014-09-10 |

Interface for GPRS and EDGEInterfa

ceBetween Description

Gb BSC-SGSN It is used to carry information concerning packet data transmission, mobility management

Gn SGSN - GGSN

is used both for control signalling between SGSN and GGSN as well as for tunnelling of end user data within the backbone network between the two nodes.

Gp SGSN-Other PLMN- GGSN

interface is defined between two GSNs of different PLMN for exchanging the user profile and other signaling information between a SGSN and GGSN of another area.

Gf SGSN-EIR is used between SGSN and EIR to exchange data, in order that the

EIR can verify the status of the IMEI retrieved from the UE.

Gr SGSN-HLR is used to get the user profile, the current SGSN address and the

PDP address(es) for each user in PLMN.

Gc GGSN-HLRis used by GGSN to query user's location and profile to update its

location register.

Gi GGSN-External PDN

This interface connects the PLMN to external public or private packet data networks. The Gi interface is used for GGSN control signalling towards ISP servers located in IP networks such as the ISP network.

Gs SGSN-MSC/VLRis used to perform paging request of circuit switched GSM call for

combined attachment procedure.

Gd SMS-GATEWAY(SMS-GMSC)- SGSN is used to exchange short message service (SMS) messages.

© Ericsson AB 2014 | 2014-09-10 |

UE UTRAN CN

Uu Iu

UE – User Equipment RAN – Radio Access Network

UTRAN – UMTS Terrestrial RAN CN – Core Network

Basic UMTS Architecture

© Ericsson AB 2014 | 2014-09-10 |

3G rel99 Architecture (UMTS) — 3G Radios

SS7

IP

BTS

BSCMSC

VLR

HLRAuC

GMSC

BSS

SGSN GGSN

PSTN

PSDN

CN

CD

GcGr

Gn Gi

Abis

Gs

B

H




RNS — Radio Network System

RNC — Radio Network Controller

CN — Core Network








AE PSTN

2G MS (voice only)


UMTS — Universal Mobile Telecommunication System

Gb

3G UE (voice & data)

Node B

RNC

RNS

Iub

IuCS

ATM

IuPS

© Ericsson AB 2014 | 2014-09-10 |

Mobile Softswitch Definition

Classic MSC(Control and Switching)

MSC Server(Control)

Mobile Media Gateway(Switching)

Mobile Softswitch SolutionClassic MSC Solution

MSC

MSC-S

MGw

Control Layer

Connectivity Layer

Classic circuit-switched network

TDM

MSC

MSC MSC

MSC MSC

Layered Architecture network

IP

MSC-S

MGw

MGw MGw

MGw MGw

Classic MSC(Control and Switching)

MSC Server(Control)

Mobile Media Gateway(Switching)

Mobile Softswitch SolutionClassic MSC Solution

MSCMSC

MSC-SMSC-S

MGwMGw

Control Layer

Connectivity Layer


TDM

MSC

MSC MSC

MSC MSC


IP

MSC-S

MGw

MGw MGw

MGw MGw

Control Layer

Connectivity Layer

Control Layer

Connectivity Layer


TDM

MSC

MSC MSC

MSC MSC


TDM

MSC

MSC MSC

MSC MSC

TDM

MSCMSC

MSCMSC MSCMSC

MSCMSC MSCMSC


IP

MSC-S

MGw

MGw MGw

MGw MGw


IP

MSC-S

MGw

MGw MGw

MGw MGw

IP

MSC-SMSC-S

MGwMGw

MGwMGw MGwMGw

MGwMGw MGwMGw

Normal MSC uses group switch and ET devices to switch calls. All voice and CS data use the group switch as the payload transport.

In MSC-S the voice/CS data transport functionality is performed by MGW. The MSC-S only controls the MGW's switching function.

© Ericsson AB 2014 | 2014-09-10 |

3G rel4 Architecture (UMTS) — Soft Switching

SS7

IP/ATM

BTS

BSCMSC Server

VLR

HLRAuC

GMSC server

BSS

SGSN GGSN

PSTN

PSDN

CN

CD

GcGr

Gn Gi

Gb

Abis

Gs

B

H




RNS — Radio Network System

RNC — Radio Network Controller

CN — Core Network








ANc

2G MS (voice only)


Node B

RNC

RNS

Iub

IuCS

IuPS

3G UE (voice & data)

Mc

CS-MGW

CS-MGWNb

PSTNMc

ATM

© Ericsson AB 2014 | 2014-09-10 |

3G-BLOCK

› MGW (Media Gateway )acts as an interface between the different Core Network domains and the 2G and 3G RANs.

› MSC-S(MSC-SERVER) is responsible for setting up, routing, and supervising calls to and from the mobile subscriber (mobility management, handover, ect).

› Node B functions:Call Processing,Radio access,Performance Monitoring,Network interface,Random Access detection

› RNC functions:Radio Resource Management,User Mobility Handling,Interfaces

© Ericsson AB 2014 | 2014-09-10 |

Interface of WCDMA

Interface

Between Description

Uu MS to Node-B The interface between the UE and the Node-B

Iub Node-B to RNC

This interface is used between the RNC and BTS to support the services offered to the WCDMA users and subscribers. The interface also allows control of the radio equipment and radio frequency allocation in the BTS.

Iur RNC-RNC The interface between two RNCs

Iu-cs RNC-MSC/MGw

The RNC-MSC/MGw interface is used to carry the user plane (user data as speech, CS data) and control plane (signaling as information concerning WCDMA-RAN management, call handling, mobility management).

Iu-ps RNC- SGSN

The RNC - SGSN interface is used to carry the user plane (user data) and control plane (signaling, as information concerning mobility management, session management, packet data transmission).

© Ericsson AB 2014 | 2014-09-10 | 21

MME

S1-MME S1-U

LTE

IP networks

eNodeB

SGSN

Iu CPGb

2G 3G

S3

BSC

BTS

RNC

Node B

HLR/HSS

PCRF

Iu UP

S11

Gr

S10

S6a

SGi

X2

Iur

S7

Non-3GPP access

S2a/b

The PDN and Serving GW may be separate nodes in some scenarios

(S5 in-between)Only PS Domain shown

S4

From 3GPP to LTE/SAE

PDN GW

SAE GW

Serv GW

S5

© Ericsson AB 2014 | 2014-09-10 |

LTE blocks

› Radio Base Station eNode B for Functions Radio Resource Management

› SAE GW - System Architecture Evolution gate way

› Serving Gateway S-GW also sometimes called Aggregation Gateway AGW (User Plane Node). . Its main purpose is to manage the user plane mobility and it also acts as the main border between the Radio Access Network, RAN and the core network. The SGW also maintains the data paths between the eNodeBs and the PDN Gateways. In this way the SGW forms a interface for the data packet network at the E-UTRAN.

PDN Gateway, PGW: The LTE SAE PDN gateway provides connectivity for the UE to external packet data networks, fulfilling the function of entry and exit point for UE data. The UE may have connectivity with more than one PGW for accessing multiple PDNs.

› Policy and Charging Rules Function, PCRF: This is the generic name for the entity within the LTE

SAE EPC which detects the service flow, enforces charging policy. For applications that require dynamic policy or charging control, a network element entitled the Applications Function, AF is used.

› Mobility Management Entity MME (Control Plane Node)-MME is the main control node for the LTE SAE access network . Its function are Idle mode UE tracking , Idle mode UE tracking ,Bearer activation / de-activation ,Intra-LTE handover involving core network node location ,Interacting with HSS to authenticate user on attachment and implements roaming restrictions , Paging procedure

© Ericsson AB 2014 | 2014-09-10 |

LTE interface S1-MME: control plane protocol between eNodeB and MME . In the control plane, more similar to Radio Access Network Application Part (RANAP), with some simplifications and changes

S1-U: user plane tunneling interface between eNodeB and Serving GW. the In user plane, based on GTP User Data Tunnelling (GTP-U) (similar to today’s Iu and Gn interface)

S5: user plane tunneling interface between Serving GW and PDN GW

S8: user plane tunneling interface between Serving GW and PDN GW for roaming

S10: control plane interface between MME and MME

S11: control plane interface between MME and Serving GW.

S4: user plane tunneling interface between SGSN and PDN GW . Provides related control and mobility support between GPRS Core and the 3GPP Anchor function of Serving GW

S3: control plane interface between MME and SGSN. enables user and bearer information exchange for inter 3GPP access network mobility in idle and/or active state

X2 Interface: The interface between eNodeB. Mainly used to support active mode UE mobility and May also be used for multi-cell Radio Resource Management (RRM) functions

S6a : Interface b/w MME to HSS. Enables transfer of subscription and authentication data for authenticating/authorizing user access to the evolved system between MME and HSS.

Sgi : Interface between SAE GW to IP network. Packet data network may be an operator external public or private packet data network or an intra operator packet data network, e.g. for provision of IMS services.

© Ericsson AB 2014 | 2014-09-10 |

SDPCCN

HLR

Core Node

MSC

GGSN

SGSN

VXML IVR0..n

AIR

AF

EMA

MINSET

VS

LAPU

PaymentGateway

EXT

EMM

STP

Charging System

INS

SMSC

CAPV3

Gx / Gy

Sigtran

CIP-IP

ISUP

XML/http

CS1 +

SMPPXML/RPC

XML/http

EMAP

XML/RPC

XML/http

CAI

DNS

DNS etop-up

Online Recharge

CAI

DNS

MML

CAI/PAMIXML/http

CC API

PAMI

FTP

XML/http

© Ericsson AB 2014 | 2014-09-10 |

Charging System Elements

SDP (Service Data Point) : The SDP network element contains the database with subscribers and account information. It also provides rating of calls and events as well as post processing of Charging Data Records (CDRs) and initiation of Unstructured Supplementary Service Data (USSD) notifications and SMS notifications.

SDP is also used to trigger the setup of a USSD callback call.

CCN (Charging Control Node) : Service Control Point - Manages real-time charging sessions from ”outside world (Telecom Nodes)” in towards Charging System, as well as charging interrogation sessions to SDP.

CCN logic is able to handle circuit switched calls, data & SMS.

CCN also terminates the Diameter Credit Control Application (DCCA) for Charging System.

CCN contains service logic for the Diameter service charging application to support content-based services.

© Ericsson AB 2014 | 2014-09-10 |

AIR (Account Information and Refill System) :

AIR handles external integration of user communication and administrative network elements.

AIR has three function groups; refill function, adjustment function, and the inquiry and update function from 3rd party Application

AIR handles account information in the form of inquiries and account administration.

It supports a number of file-based batch jobs for making bulk adjustments, promotions, and refills.

AIR can handle multiple Voucher Servers (VSs).

AF (Account Finder) : AF is a network element that provides SDP id information for subscriber accounts in the system. AF enables centralized management of multiple SDPs.

AF is always collocated with AIR.

VS (Voucher Server) : VS is responsible for the administration and storage of vouchers.


© Ericsson AB 2014 | 2014-09-10 |

MINSAT (Mobile IN Service Administration Tool):

MINSAT or Ericsson Customer Management System handles subscriber administration for Charging System. No traffic is handled, but interaction in real time with other systems for provisioning and updates are possible through GUI and through the external interfaces provided.

At subscriber provisioning and removal, MINSAT or Ericsson Customer Management System may interact with both the Account Finder (AF) and SDP, as well as optionally connect with external systems.

MINSAT or Ericsson Customer Management System is used to display the call and account history.

It is customer care interface as well.

EMA (Ericsson Multi Activation) :

EMA provides operators with a uniform machine-to-machine interface between business system and network elements that store subscription-related information. It may be used for first time ADMIN provisioning of subscriber on core node (HLR) & may also used for service control Barring and unbarring on HLR.


© Ericsson AB 2014 | 2014-09-10 |

VXML-IVR (Voice Extensible Markup Language Interactive Voice Response System) :

The subscriber can use IVR to change and inquire about account information, for example, refills and account balance enquiries.

IVR interacts with Account Information and Refill System (AIR) to implement the services it provides to subscribers. IVR can also be used for contacting customer care.

VXML-IVR is a standalone IVR. For VXML-IVR, the Mobile service Switching Centre (MSC) forwards an IVR call to VXML-IVR. VXML-IVR then handles the call over an ISUP, or SIGTRAN, channel. Call flow logic and announcements initiated by VXML-IVR are stored in VXML-IVR itself.

Ericsson Multi Mediation Solution (EMM) :

The Multi Mediation Solution is a flexible product used for handling the CDRs for further processing in other network elements.

The Multi Mediation Solution is necessary for processing call history and for offline cost and credit control.

The Multi Mediation Solution filters CDRs to be handled for offline cost and credit control, and reformatted copies of the selected CDRs are sent on a unified interface to SDP where charging takes place.


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introduction to telecom networks

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