Exercise 1 (Solution)
WAP/WTA was developed to: Support exclusively MexE.
To design and program application locally on the ME. To allow interaction between the SCP and the ME. To support radio interface protocols.
Exercise 2 (Solution)
The abbreviation OSA stands for Open Systems Architecture. a. True
b. False
Exercise 3 (Solution)
Which of the following is, or will be, a characteristic of the Virtual Home Environment (VHE) (Choose two)?
Allows the subscribers to use their services whilst roaming. It is only possible in UMTS.
It is the same as a SMSC (Short Message Service Centre). VHE is possible because of CAMEL.
VHE is located within the HLR.
Enable the creation of services to the subscribers to customise their own environment.
wiximaji.en.lmm/habameto.en.slo
Exercise 4 (Solution)
A cluster is:
A location area.
An area of cells, where the hole set of frequency is used once. Cellular network of one operator.
Coverage area of one BSC. Coverage area of one BTS.
Exercise 5 (Solution)
What does Handover means?
Changing the cell during a connection. Changing the area of one PLMN. Changing the location area.
Changing the cell while there is no connection.
Exercise 6 (Solution)
How many HF channels do GSM 900 offers? 19
174 374 124
Exercise 7 (Solution)
Which features does not belong to GSM phase 2+? Blue Tooth
wiximaji.en.lmm/habameto.en.slo
HR EFR CAMEL
wiximaji.en.lmm/
UMTS Network
Architecture
Contents
1 UMTS Network Architecture...2
1.1 Module Objectives...2 1.2 UMTS Network Architecture...3 1.3 The UMTS Release 99 Network Architecture... 7 1.4 The UMTS Release 4 Architecture... 10 1.5 The UMTS Release 5 Architecture... 33 1.6 The UMTS Release 6 Overview ... 46 1.7 Long Term Evolution...51 1.8 Appendix...55
2 Exercises...56
wiximaji.en.lmm/batadipu.en.slo
1
UMTS Network Architecture
1.1
Module Objectives
The aim of this module is to give the student the conceptual knowledge needed for explaining the UMTS-network architecture. Topics to be covered in this module include visualizing the whole network and identifying the elements of each subsystem.
After completing this module, the participant should be able to: Briefly explain the network subsystems of Release 99. Identify and list the requirements of UMTS mobile terminals. Identify and list the network elements used in Release 4.
Identify and list the network elements used within the radio access network (RAN), in terms of the name and function.
Identify the main functions of an RNC.
Identify and list the network elements used within the core network. Briefly explain Intelligent Network (IN) and its function in 3G network. Briefly explain the IP Multimedia Subsystem (IMS) concept.
wiximaji.en.lmm/batadipu.en.slo
1.2
UMTS Network Architecture
A Universal Mobile Telecommunications System (UMTS) network can be
visualized from different angles, such as from the point of view of the user plane, control plane, or the function of each subsystem. In this module we will look at UMTS from the latter angle, where the focus is on the different network elements within the network.
The UMTS network architecture can be divided into three subsystems: Radio Access Network.
Core Network including the network elements for service groups. Network Management Subsystem.
This separation will allow modularity in the composition of networks. The objective is to be able to combine any 3G CN with any 3G RAN. In addition, technical enhancements and updates of individual modules will be able to be introduced more easily, quicker and at less expensively due to the separation of functions. Each subsystem can be further divided into separate technologies. For example, the RAN (Radio Access Network) is compromised of different air interface
technologies, such as GSM EDGE Radio Access Network (GERAN), UMTS Terrestrial Radio Access Network (UTRAN) and future solutions such as WLAN, 1ExTREME and 4G.
The core network is today clearly divided into: Circuit Switched (CS) domain.
Packet Switched (PS) domain.
The network elements of the circuit switched domain are offering CS bearer services. They are inherited from GSM: MSC/VLR and GMSC. The packet
switched domain is responsible to offer PS bearer services. Based on GPRS core network elements, the PS bearer services are currently non-real time services. But standards are on the way to enhance this infrastructure, so that also real-time services can be served via the PS domain transmission infrastructure.
The CS and PS domains share some network elements. These common CS and PS domain network elements are the HLR, AC, and EIR.
A set of service platforms was specified in GSM. These are now – in an
enhanced version – also available in UMTS. Network elements for service groups include CAMEL, text telephony, Location Based Services (LBS) network
elements. As can be seen service provisioning is partly located in the core
network and contains all the service-enabling platforms that support the multitude of 3G services that an operator can offer.
wiximaji.en.lmm/batadipu.en.slo
The UMTS specifications stipulated that the new air interface and system capabilities should reuse the existing 2G systems, such as GSM and GPRS. Therefore, it is envisaged that operators can quickly rollout network once the equipment is available. The standards dictate the configuration of the open interfaces and the function of each subsystem; however, the implementation is vendor or operator specific. This has led into much more modular network architecture than we find in today's GSM networks. NSN fully supports open interfaces. The network elements are designed to be modular and are built in the manner that the functions can mature and evolve from new developments.
Each year, the UMTS specifications are upgraded to support continuing functionality in the network. The next version of the specifications is known as UMTS Release 4 followed UMTS Release 5, Release6 and further.
UMTS Release 4 will focus among others on having a specified IP or ATM Telephony Core. The focus of Release 5 is to have IP Multimedia Subsystem.
wiximaji.en.lmm/batadipu.en.slo
1.2.1
Common UMTS Network Elements
1.2.1.1 Home Location Register
The Home Location Register (HLR) is a database in charge of the management of the mobile subscribers. There may be one or more HLRs in GSM PLMN The HLR is always associated with an Authentication Center (AC). It participates in different procedures, for e.g.:
It sends all necessary data to the VLR.
It supports the call setup in case of Mobile Termination Call (MTC) by sending routing information to the Gateway MSC (Interrogation). It transmits the security parameters from AuC to VLR on request. An HLR contains different semi-permanent mobile subscriber data, e.g.:
IMSI: International Mobile Subscriber Identity
MSISDN: Mobile Station International ISDN number Packet Data Protocol (PDP) address(es), e.g. IP address
Services: Bearer Services (BS), Tele Services (TS), Supplementary Services (SS)
A list of all the group IDs a service subscriber is entitled to use to establish voice group or broadcast calls
CAMEL Subscriber Information(s)
Service Restrictions (e.g. roaming limitations)
Additionally, the HLR contains different temporary information of the mobile subscriber, e.g.:
VLR and SGSN addresses Mobile station Roaming Number SMS flags
wiximaji.en.lmm/batadipu.en.slo
1.2.1.2 Authentication Center
The Authentication Center (AuC) is responsible to store the secret Keys of the subscribers and the security algorithm, which are necessary for the generation of the GSM and UMTS security parameters. On request of the VLR respectively the SGSN the AuC generates the security parameters. They are delivered via HLR to VLR/SGSN to enable Authentication, Ciphering and Integrity Check.
The AuC is connected only with the HLR via the non-standardised interface H. The HLR requests data for authentication and cipher setting from the AuC. The HLR can store this data, and makes it available to the VLR and SGSN on demand. The data delivered from the AuC is used for:
Mutual authentication of the SIM-card (via IMSI) and the serving PLMN Delivering a key to check the communication integrity over the radio path between the user equipment and the VPLMN
Ciphering over the radio path between the user equipment and the RNC.
1.2.1.3 Equipment Identity Register
Equipment Identity Register (EIR) optional database is used to verify the
International Mobile Equipment Identity (IMEI) numbers. The EIR is organised in three lists:
1. Black list 2. Grey list 3. White list
The black list holds IMEIs, which are forbidden in the PLMN. The grey list holds IMEIs under supervision by law enforcement agencies, and the white list holds IMEIs, which are allowed to access the PLMN.
A mobile phone can be also classified as to be unknown in the EIR. The interface F connects the EIR with the VLR, while the Gf interface links it with the SGSN. The EIR is connected to:
The SGSN via Gf interface The VLR via F interface
wiximaji.en.lmm/batadipu.en.slo
1.3
The UMTS Release 99 Network
Architecture
The UMTS networks are based on GSM Phase 2+ Core Networks. This approach safeguards the investments made by today's GSM network operators and
reduces the 3G implementation risks. The UMTS Terrestrial Radio Access
Network (UTRAN) is connected to the enhanced Phase 2+ Core Network(CN) via Iu interface. The GERAN and UTRAN can be connected to the same CN. The GSM Mobile Station (MS) is connected to the GERAN via GSM radio interface Um, the UMTS User Equipment (UE) to UTRAN via UMTS radio interface Uu.
UMTS Release 99 Core Network
CN (Core Network )
circuit switched (cs ) domain
packet switched (ps ) domain
common cs & ps network elements G ERAN UTRAN MSC/VLR GMSC HLR EIR AC GGSN SGSN PSTN/ ISDN corp. network WAP PDN IP - backbone CG Billing Centre BG Inter -PLMN Network CSE
Fig. 2 UMTS Release 99 Core Network
Important note: In order to allow a smooth evolution, some network elements are used in the 2G and 3G context, such as the MSC. In this material, it will be normally called MSC. If a specific reference to the second or third generation is required, it will be called 2G-MSC and 3G-MSC, respectively. The same is true for the SGSN.
wiximaji.en.lmm/batadipu.en.slo
1.3.1
Circuit Switched (CS) Domain Network Entities
CS Domain
The CS Domain of the UMTS CN consists of the following functions: MSC : Mobile Services switching Center
GMSC : Gateway MSC
SMS-GMSC : Short Message Service Gateway MSC SMS-IWMSC : Short Message Service Interworking MSC VLR : Visitor Location Register
TC/IWF : Transcoding & Interworking Function
PS Domain
The PS Domain of the UMTS CN consists of the following functions: GGSN : Gateway GPRS Support Node
SGSN : Serving GPRS Support Node CGF : Charging Gateway Function BG : Border Gateway Function
Entities common to the CS & PS Domain
HLR : Home Location Register AUC : Authentication Center EIR : Equipment Identity Register CSE : CAMEL Service Environment
UMTS Terrestrial Radio Access Network UTRAN & UE The UTRAN consists of the following functions:
RNC : Radio Network Controller Node B
wiximaji.en.lmm/batadipu.en.slo
1.3.2
Visitor Location Register
The Visitor Location Register (VLR) is responsible to aid the MSC with information on the subcriber, which are temporarily in the MSC service area. Therefore, it is always associated with an MSC.
The VLR request the subscriber profiles of sucscriber with activated MS/UE ithe MSC service area from the Home Location Register (HLR) and stores them temporarily. Temporarily means as long as the subscriber is not registered in a new MSC/VLR, even if he deactivated the MS/UE.
Additional to the semi-permanent subscriber data received from the HLR, the VLR stores temporary data, e.g. information on the subscribers current location(the Location Area), the state of activation (Attached/Detached).
Furthermore, the VLR is responsible for the initiation of security functions, e.g. the Authentication procedure, the start of ciphering and the TMSI re-allocation.
Examples of subscriber data in the VLR: MSISDN: Mobile Subscriber ISDN No.
IMSI: International Mobile Subscriber Identity TMSI: Temporary Mobile Subscriber Identity LMSI: Local Mobile Subscriber Identity MSRN: Mobile Station Roaming Number LAI: Location Area Identity
Authentication Parameter
wiximaji.en.lmm/batadipu.en.slo
1.4
The UMTS Release 4 Architecture
UMTS networks are designed to offer a wide range of multimedia services. A consequence of more variable services is that the core network must offer more efficient and flexible transport options than the Release 99 network does.
Therefore the UMTS Core Network CS domain is a central aspect of Release 4 modification (TS 23.002). The intention of these modifications is a separation of the call control from the transport the user data. A wide range of bearers must be made available in the core and radio access network to make these new services available for the subscriber. Today’s exchanges and MSCs are optimized for voice transport. An MSC is responsible for:
Bearer control and bearer management Call control
Service provisioning
With so many different tasks combined in one network element, any modification is costly and time consuming. With a traditional MSC it is very hard for operators to react fast to changing demand in the market. More flexible solutions are required.
Beginning with UMTS Release 4, call control and bearer control and management are separated. The separation of planes is done in the UMTS Release 4 circuit switched domain.
The UMTS Release 99 network elements MSC/VLR, and GMSC are substituted by the network entities MSC-Server, GMSC-Server and CS-MGW (Circuit
wiximaji.en.lmm/batadipu.en.slo PSTN/ ISDN Bearer Level Call Control Level MSC Server HLR GMSC Server CS - MGW CS - MGW GERAN UTRAN
Applications and Services
Mc (H.248/MEGACO)
Mc
CAP CAP
Nb (e.g. ATM, IP)
Nc(e.g. BICC) A Iu C D Iu A
MEGACO: IETF Media Gateway Control protocol H.248: ITU protocol for Media Gateway Control
PS Domain unchanged compared to R`99 PS Domain unchanged compared to R`99 R`4 TS 23.002 (G -)MSC Server: •Call Control • Mobility Management • MGW Control • VLR functionality • CDRs • (HLR -Interrogation) MGW: •Bearer Control
• Transmission Resource Management • Data Format Conversion
• Transcoding CDR: Call Data Records
BICC: Bearer Independent Call Control MGW: Media Gateway
UMTS CN Release 4 CS Domain
wiximaji.en.lmm/batadipu.en.slo
1.4.1
MSC-Server
The MSC-Server is responsible for all call control tasks of the MSC and VLR. Its tasks include the:
Call control of mobile originated and mobile terminated calls in the CS domain
The VLR functionality. For all subscribers in the MSC-Server supply area, it holds temporarily the subscriber profile, location information, identities, etc. Interaction with the CS-MGW. The MSC-Server determines the QoS
parameters required for the subscriber’s application. It is then the
responsibility of the CS-MGW to make the bearer available. The interaction between MSC-Server and CS-MGW is done via an open interface, based on the ITU-T H.248 standard.
Termination of UE-network and network-network signaling. The UE-network signaling is done via the Iu-CS interface. For the network-network signaling, signaling protocols such as the BICC (Bearer Independent Call Control) protocol can be used.
CDR collection.
The MSC Server is connected to other network elements via the following interfaces:
A-interface : to the GSM Base Station Controller BSC D-interface : to the HLR
F-interface: to the EIR Gs-interface: to the SGSN Iu CS-interface: to the RNC
Mc-interface: to the CS-MGW for separation between call control and bearer control. The ITU standard H.248 respectively its IETF standard equivalent Media Gateway Control (MEGACO) is used on Mc.
Nc-interface: to GMSC Server for Bearer-Independent Call Control (BICC)
1.4.2
GMSC-Server
GMSC-Server
The GMSC-Server adopts the call control tasks of the GMSC. Its tasks include: Interrogation of the HLR
Termination of network-network signaling Interaction with the CS-MGW
wiximaji.en.lmm/batadipu.en.slo
1.4.3
Circuit Switched – Media Gateway (CS-MGW)
Circuit Switched – Media Gateway (CS-MGW)
The CS-MGW is responsible for bearer control. Its functions include: Bearer control: The requirements for the bearer control are set in the
(G)-MSC-Server. The CS-MGW gets this information via an open interface. The CS-MGW must determine, whether it can make bearers available in accordance to the QoS parameters set.
Bearer channel termination: The different transmission technologies may be in use, e.g. ATM and IP over Ethernet. The ATM bearer then ends in the MGW and the IP bearer begins at the MGW for user data transport. Media conversion and payload processing: If the CS-MGW is interfacing UTRAN, voice information must be processed. E.g. voice may be transmitted with 64 kbps in the core network, but for the radio interface, 12.2 kbps
speech is required. The UMTS specific voice codec is found in the MGW. The same is true for conference bridges, echo cancellers, etc.
Mobile specific functions: A CS-MGW must support mobility specific functions, such as SRNC relocation and handover procedures.
The CS MGW can also be connected to other networks such as PSTN and PLMN using the following interfaces:
A-interface : to the GSM Base Station Controller BSC Iu-CS interface: to the RNC
Nb-interface: to other MGW. Different options are possible on Nb for user data transfer and bearer control signaling (e.g. ATM, IP).
wiximaji.en.lmm/batadipu.en.slo
1.4.3.1 Mobile Switching Centre Server
Mobile Switching Centre Server (MSC server) concept offers common core network for the GSM and the UMTS subscribers. Release 99 introduces the UTRAN network. NSN's 3G-MSC offers connections both towards the GSM Base Station Subsystem (BSS) and towards the WCDMA-based UMTS Terrestrial Radio Access Network (UTRAN).
When the network architecture based on UMTS Release 4 is introduced, the user and control planes are separated in the network. This means that the 3G-MSC evolves to the direction where the MSC's switching functions are brought to the Media Gateway (MGW) product, and the MSC evolves to an MSS-like product. The MSS product provides call control logic for terminals that use circuit switched logic.
MSS mainly comprises the call control and mobility control parts of a GSM/UMTS MSC. The MSS is responsible for the control of mobile originated and mobile terminated circuit switched calls. It terminates the user-network signalling and translates it into the relevant network – network signalling. The MSS also
contains a VLR to hold the mobile subscribers' service data and CAMEL related data. MSS controls the parts of the call state that pertain to connection control for media channels in a MGW.
The MSC server connects to the Media Gateway using the H.248 protocol (MEGACO). The physical connection between the MSC server and Media
Gateway (MGW) is Ethernet. The interface between two MGWs performs bearer control and transport through the ATM backbone by using several ATM
Adaptation Layer protocols (AAL1, AAL2, and AAL5) or the IP backbone. The functionality of the MSC server can be divided into two roles: Visited MSS (VMSS) and Gateway MSS.
VMSS contains VLR and controls the MGW that is connected towards the (BSS and UTRAN) radio networks.
Gateway MSS functionality is to control the MGW that is performing interworking between packet core network and the external PSTN/ISDN network.
The NSN product that performs the Gateway MSS functionality is called Gateway Control Server (GCS).
The HLR is a database in charge of the management of the mobile subscribers. There may be one or more HLRs in GSM PLMN
The HLR is always associated with an Authentication Center (AC). It participates in different procedures, for e.g.:
It sends all necessary data to the VLR.