Docstoc

WCDMA Structure

Document Sample
WCDMA Structure Powered By Docstoc
					                                                                              Error! Use the Home tab to
                                                                          apply 标题 1 to the text that you
       Basic Principles of WCDMA System                                              want to appear here.




             Chapter 3 WCDMA System Structure

3.1 Overview
             The UMTS (Universal Mobile Telecommunications System) is the third generation
             mobile telecommunication system by using the WCDMA air interface technology,
             usually called the WCDMA telecommunication system. It adopts a structure similar to
             the second generation mobile telecommunication system, including the RAN (Radio
             Access Network) and the CN (Core Network). The RAN is used to process all the
             radio-related functions, while the CN is used to process all voice calls and data
             connections within the UMTS system, and implements the function of external network
             switching and routing. Logically, the CN is divided into the CS (Circuit Switched)
             Domain and the PS (Packet Switched) Domain. UTRAN, CN and UE (User Equipment)
             together constitute the whole UMTS system, the structure of which is shown in Figure
             3-1.

                UE          AN                          3G CN                        External network

                                                        3G CS
                                               MSC£ ¯ LR£ ¬ MSC£ ¬smSSF
                                                    V     G      g                        PSTN

                                                  Service application
                          UTRAN                         domain
                                                       HLR, SCP


                                                         3G PS                          Internet
                                                       SGSN,GGSN




                                          Figure 3-1 UMTS system structure


             From the point of view of the 3GPP R99 standard, the UE and the UTRAN (UMTS
             Terrestrial Radio Access Network) are composed of new protocols, and the design is
             based on WCDMA radio technologies. However, the CN adopts the definition of
             GSM/GPRS, so it not only can implement smooth transition of the network, but also can
             implement global roaming at the initial phase of 3G network construction.

3.1.1 Composition of the UMTS Network System

             The composition of the UMTS network is shown in Figure 3-2.




2004-08-24                     Confidential Information of Huawei. No                   Page3-1, Total19
                                  Spreading without Permission
                                                                               Error! Use the Home tab to
                                                                           apply 标题 1 to the text that you
       Basic Principles of WCDMA System                                               want to appear here.


                            Uu                          lu


                                 Node B
                                                             MSC/                        PLMN PSTN
                                              RNC                           GMSC
                                                             VLR                          ISDN,etc
                    USIM         Node B
                       Cu             lub         lur                HLR
                    ME           Node B
                                              RNC            SGSN           GGSN          INTERNET
                                 Node B
                      UE                     UTRAN                            CN       External Networks




                                   Figure 3-2 Composition of the UMTS network system


             As shown Figure 3-2, the UMTS network system includes the following parts:

             1. UE (User Equipment)

             As the user terminal equipment, the UE exchanges data with network equipment
             through the Uu interface, and provides such kinds of services within CS and PS
             domains as common voice, data communication, mobile multi-media and Internet
             application (For example, E-mail, WWW browse and FTP).
             UE includes the two parts below:
                 ME (Mobile Equipment): Providing application and services.
                 USIM (UMTS Subscriber Module): Providing subscriber identification.

             2. UTRAN (UMTS Terrestrial Radio Access Network)

             UTRAN is divided into Node B and RNC (Radio Network Controller).
                 Node B
             Node B is the base station of the WCDMA system (i.e. radio transceiver), and it
             interconnects with RNC via the standard Iub interface and processes the physical layer
             protocols of the Uu interface. Its main functions include spreading/de-spreading,
             modulation/demodulation, channel coding/decoding, and conversion between
             baseband signals and RF signals.
                 RNC (Radio Network Controller)
             RNC (Radio Network Controller) implements such functions as connection
             establishment and release, handover, macro diversity and the management and
             control of radio resources. The details are given as follows:
             1)   Provides the system information broadcast and system access control functions
             2)   Provides such mobility management functions as handover and RNC transition
             3)   Provides radio resource management and control functions such as macro
                  diversity combination, power control and radio bearer allocation
             3. CN (Core Network)

             CN (Core Network) is responsible for connecting other networks as well as
             communicating and managing UEs. The core network equipment of different protocol
             versions in the WCDMA system differ. Generally, the R99 core network is divided into
             the CS domain and the PS domain. The R4 core network is the same as the R99 core
             network, but in the R4 core network, the MSC function of R99 CS is implemented by the
2004-08-24                       Confidential Information of Huawei. No                   Page3-2, Total19
                                    Spreading without Permission
                                                                            Error! Use the Home tab to
                                                                        apply 标题 1 to the text that you
       Basic Principles of WCDMA System                                            want to appear here.

             two separate entities: MSC Server and MGW. The R5 core network is the same as the
             R4 core network except that R5 has been added with an IP multi-media domain.
             The R99 core network has the following function entities:
             1)   MSC/VLR
             MSC/VLR is a functional node of the CS domain in the WCDMA core network. It
             connects with UTRAN via the Iu-CS interface, with external networks (such as PSTN
             and ISDN) via the PSTN/ISDN interface, with HLR/AUC via the C/D interface, with
             MSC/VLR, GMSC or SMC via the E interface, with SCP via the CAP interface, and with
             SGSN via the Gs interface. Its main functions are call control, mobility management,
             authentication and ciphering of the CS domain.
             2)   GMSC
             GMSC is the gateway node between the CS domain of the WCDMA mobile network
             and external networks, and it is an optional functional node. It connects with external
             networks (PSTN, ISDN and other PLMN) through the PSTN/ISDN interface, connects
             with HLR through the C interface and connects with SCP through the CAP interface. It
             implements the routing function of incoming calls in the VMSC function and
             inter-network settlement function of such external networks as fixed networks.
             3)   SGSN
             SGSN (Serving GPRS Support Node) is a functional node of the PS domain in the
             WCDMA core network. It connects with UTRAN through the Iu-PS interface, with
             GGSN through the Gn/Gp interface, with HLR/AUC through the Gr interface, with
             MSC/VLR through the Gs interface, with SCP through the CAP interface, with SMC
             through the Gd interface, with CG through the Ga interface and with SGSN interface
             through the Gn/Gp interface. And its main functions are route forwarding, mobility
             management, authentication and ciphering of the PS domain.
             4)   GGSN
             GGSN (Gateway GPRS Supporting Node) is a functional node of the PS domain in the
             WCDMA core network. It connects with SGSN through the Gn/Gp interface and with
             external data networks (Internet/Intranet) through the Gi interface. It provides the
             routing and encapsulation of data packets between the WCDMA mobile network and
             the external data networks. Its major functions are to provide interfaces to external IP
             packet networks. It needs to provide the gateway function for UE to access external
             packet networks. From the point of view of external networks, GGSN looks as if it were
             a router of all user IP networks in the addressable WCDMA mobile network, and it
             needs to exchange routing information with external networks.
             5)   HLR
             HLR (Home Location Register) is a functional node shared by the CS and PS domains
             in the WCDMA core network. It connects with MSC/VLR or GMSC through the C
             interface, with SGSN through the Gr interface, and with GGSN through the Gc interface.
             And its main functions are to store subscription information for subscribers, support
             new services and provide the enhanced authentication function.


3.2 Basic Structure of UTRAN
             The structure of UTRAN is shown in Figure 3-3:
             UTRAN includes one or several Radio Network Subsystems (RNSs). A RNS is
             composed of one RNC and one or several Node Bs. The Iu interface is used between
             RNC and CN while the Iub interface is adopted between RNC and Node B. Within
             UTRAN, RNCs connect with one another through the Iur interface. The Iur interface
             can connect RNCs via the direct physical connections among them or connect them
2004-08-24                     Confidential Information of Huawei. No                 Page3-3, Total19
                                  Spreading without Permission
                                                                                  Error! Use the Home tab to
                                                                              apply 标题 1 to the text that you
       Basic Principles of WCDMA System                                                  want to appear here.

             through the transport network. RNC is used to allocate and control the radio resources
             of the connected or related Node B. However, Node B serves to convert the data flows
             between the Iub interface and the Uu interface, and at the same time, it also
             participates in part of radio resource management.


                                CS                         CN                    PS

                                     Iu                                                Iu
                 RNS
                                                                  RNS
                                                          Iur
                                RNC                                                 RNC


                        Iub                Iub                            Iub               Iub

                     Node B               Node B                        Node B              Node B




                                                 Figure 3-3 UTRAN structure



3.2.1 System Interfaces

             UTRAN has the following main interfaces:

             1. Cu interface

             The Cu interface is the electrical interface between the USIM card and ME, and it
             adopts the standard interface.

             2. Uu interface

             The Uu interface is the radio interface of WCDMA. UE accesses the fixed network of
             the UMTS system through the Uu interface, so we can say the Uu interface is the most
             important open interface in the UMTS system.

             3. Iur interface

             The Iur interface is the interface connecting RNCs. It is specific to the UMTS system for
             mobility management of UEs in RAN. For example, when different RNCs perform soft
             handover, all UE data are transmitted from the working RNC to the candidate RNC
             through the open standard Iur interface.

             4. Iub interface

             The Iub interface is an open standard interface connecting Node B and RNC. It allows
             RNC to connect to NodeB from another equipment manufacturer.



2004-08-24                      Confidential Information of Huawei. No                      Page3-4, Total19
                                   Spreading without Permission
                                                                                Error! Use the Home tab to
                                                                            apply 标题 1 to the text that you
       Basic Principles of WCDMA System                                                want to appear here.

             5. Iu interface

             The Iu interface is the interface between UTRAN and CN. Similar to the A interface and
             the Gb interface in the GSM system, it is also an open standard interface. It allows
             different vendor’s UTRAN and CN to connect together, and can be divided into the
             Iu-CS interface and the Iu-PS interface.

3.2.2 Basic Protocol Structure of UTRAN Interfaces

             The protocol structure of UTRAN interfaces is designed according to a universal
             protocol model. The principle of design is that logically the layer and the plane should
             be independent. If necessary, you can modify a part of the protocol structure without
             modifying other parts, as shown in Figure 3-4.



     Radio           Control Plane                                                  User Plane
    Network
     Layer            Application                                                      Data
                       Protocol                                                     Stream(s)


    Transport      Transport Network             Transport Network            Transport Network
    Network            User Plane                  Control Plane                  User Plane
      Layer
                                                    ALCAP(s)

                       Signalling                    Signalling                       Data
                       Bearer(s)                     Bearer(s)                      Bearer(s)


                                                 Physical Layer




                          Figure 3-4 Universal protocol model of UTRAN interfaces


             Horizontally, the protocol structure contains the radio network layer and the transport
             network layer. All protocols related to UTRAN are contained in the radio network layer.
             The transport network layer is the standard transmission technique adopted by UTRAN,
             and it has nothing to do with the specific functions of UTRAN.
             Vertically, it contains the control plane and the user plane.
             The control plane contains application protocols (RANAP in the Iu interface, RNSAP in
             the Iur interface and NBAP in the Iub interface) and signaling bearers to transmit these
             application protocols. Application protocols are used to build the bearers to UEs (For
             example, radio access bearer in the Iu interface, radio links in the Iur and Iub
             interfaces). These signaling bearers of these application protocols can be the same as
             or can differ from those of the Access Link Control Application Protocol (ALCAP), and
             they are established through O&M.

2004-08-24                      Confidential Information of Huawei. No                    Page3-5, Total19
                                   Spreading without Permission
                                                                             Error! Use the Home tab to
                                                                         apply 标题 1 to the text that you
       Basic Principles of WCDMA System                                             want to appear here.

             The user plane contains data flows and data bearers to carry these data flows. All
             information (such as voice and data) received or sent by UEs is transmitted through the
             user plane. The transport network control plane is located between the control plane
             and the user plane, and it is just in the transport layer, so it does not contain any
             information about the radio network control plane. It contains ALCAP and the signaling
             bearer required by ALCAP. ALCAP establishes the transport bearer for the user plane.
             By adopting the transport network control plane, the application protocol
             implementation of the radio network plane can be independent from the technique
             selected for the data bearer of the user plane.
             In the transport network, the transport bearer of the data plane in the user plane is built
             in such a way: Application protocols in the control plane conduct signaling processing
             first, which triggers the establishment of data bearer in the data plane through ALCAP.
             However, not all types of data bearers should be established through ALCAP. Without
             signaling processing of ALCAP, the transport network control plane is not needed, so
             the pre-configured data bearer should be used instead. The signaling bearer of ALCAP
             can be the same as or can differ from that of the application protocol. Usually, the
             ALCAP signaling bearer is established through O&M operations.
             The data bearer of the user plane and the signaling bearer of the application protocol
             both belong to the user plane of the transport network. In real-time operations, the data
             bearer of the transport network user plane is controlled directly by the transport network
             control plane. However, the control operation required for establishing the signaling
             bearer of the application protocol belongs to O&M operations.
             In conclusion, UTRAN obeys the following principles:
             1)   The signaling plane is separated from the data plane.
             2)   UTRAN/CN functions are separate from the transport layer, that is, the radio
                  network layer does not depend on the specific transmission technique.
             3)   Macro diversity (FDD Only) is processed totally by UTRAN.
             4)   The mobility management of RRC connections is processed totally by UTRAN.

3.2.3 Functions Implemented by UTRAN
             1)   Functions related to overall system access control
                 Admission control
                 Congestion control
                 system information broadcast
             2)   Functions related to security and confidentiality
                 Encryption/decryption of radio channels
                 Protection of message integrity
             3)   Functions related to mobility
                 Handover
                 SRNS relocation
             4)   Functions related to radio resource management and control
                 Radio resource configuration and operation
                 Radio environment survey
                 Macro diversity control (FDD)
                 Connection and release of radio bearers (RB control)
                 Allocation and cancellation of radio bearers
                 Dynamic channel allocation (TDD)
                 Radio protocol function
                 RF power control
                 RF power setting
             5)   Timing advance setting (TDD)
             6)   Radio channel coding
             7)   Radio channel decoding
2004-08-24                      Confidential Information of Huawei. No                 Page3-6, Total19
                                   Spreading without Permission
                                                                            Error! Use the Home tab to
                                                                        apply 标题 1 to the text that you
       Basic Principles of WCDMA System                                            want to appear here.

             8) Channel coding control
             9) Initial (random) access detection and processing
             10) CN distribution of NAS messages

3.2.4 RNC (Radio Network Controller)

             RNC is used to control the radio resources of UTRAN. Usually, it connects with the CS
             domain (MSC), the PS domain (SGSN) and the broadcast domain (BC, not indicated in
             the figure) through the Iu interface. The RRC protocol between UE and UTRAN
             terminates here. Logically, RNC corresponds to the Base Station Controller (BSC) in
             the GSM network.
             The RNC used to control Node B is called the Controlling Radio Network Controller
             (CRNC) of Node B, which is responsible for managing the radio resources of the cell
             under its control.
             If more than one RNS is used to connect a UE with UTRAN, all the relevant RNSs can
             be divided into the following types:
                Serving RNS (SRNS): Managing the radio connection between UE and UTRAN, It
                 corresponds to the termination point of this UE’s Iu interface (Uu interface). All
                 basic radio resource management is implemented by SRNC in SRNS, for example,
                 mapping the radio access bearer parameters to the parameters of transport
                 channels, cell handover and open loop power control. A UE connected with
                 UTRAN should have one and only one SRNC.
                Drift RNS (DRNS): Any RNS except the SRNS used by UE is called the DRNS. Its
                 corresponding RNC is DRNC. A subscriber can have none, one or several
                 DRNSs.
             Usually, the actual RNC contains all functions of CRNC, SRNC and DRNC.

3.2.5 Node B

             Node B is the base station (i.e. radio transceiver) of the WCDMA system, and it
             interconnects with RNC through the standard Iub interface to process the physical layer
             protocols of the Uu interface. Its main functions include: Spreading/de-spreading,
             modulation/demodulation, channel coding/decoding, and conversion between
             baseband signals and RF signals. Meanwhile, it implements such radio resource
             management functions as inner loop power control. Logically, it corresponds to the
             Base Transceiver Station (BTS) in the GSM network.


3.3 Basic Structure of the Core Network
             Logically, CN is divided into the circuit switched domain (CS domain), the packet
             switched domain (PS domain) and the broadcast domain (BC domain). The CS domain
             equipment provides circuit service for subscribers, or provides the entities for related
             signaling connections. Specifically, it covers the following entities: MSC, GMSC, VLR
             and IWF. The PS domain provides packet data services for subscribers, including the
             following specific entities: SGSN and GGSN. Other equipment, for example, HLR (or
             HSS), AuC and EIR are shared by the CS domain and the PS domain.
             The overall structure of the WCDMA network is defined in 3GPP TS 23.002.Now, there
             are the following three versions:
                R99 —3GPP TS 23.002
                R4 —3GPP TS 23.002
2004-08-24                     Confidential Information of Huawei. No                 Page3-7, Total19
                                  Spreading without Permission
                                                                                 Error! Use the Home tab to
                                                                             apply 标题 1 to the text that you
       Basic Principles of WCDMA System                                                 want to appear here.

                 R5 —3GPP TS 23.002

              Note:
             “R” means “Release”.

             3GPP began to formulate 3G specifications at the end of 1998 and beginning of 1999.
             As scheduled, the R99 version would be completed at the end of 1999, but in fact it was
             not completed until March, 2000. After R99, the version was no longer named by the
             year. At the same time, the functions of R2000 are implemented by the following two
             phases: R4 and R5. In principle, the R99 specification is a subset of the R4
             specification set. If R99 is added with new features, it will be upgraded to R4. Similarly,
             the R4 specification set is a subset of the R5 specification set. If R4 is added with new
             features, it will be upgraded to R5.
             For the above three versions, the specific equipment of the PS domain does not
             change, but only their protocols are upgraded and optimized. The CS domain and GSM
             network of the R99 version do not fundamentally change. In the R4 network, MSC as
             the CS domain of the CN is divided into the MSC Server and the MGW, at the same
             time, a SGW is added, and HLR can be replaced by HSS (not explicitly specified in the
             specification). In the R5 network, the end-to-end VOIP is supported and the core
             network adopts plentiful new function entities, which have thus changed the original call
             procedures. With IMS (IP Multimedia Subsystem), the network can use HSS instead of
             HLR.

3.3.1 Structure and Interfaces of the R99 Network

             To guarantee the investment benefits of operators, the design of R99 network structure
             has considered fully the 2G/3G compatibility, so as to support the smooth transition of
             GSM/GPRS/3G. Therefore, the CS domain and the PS domain are parallel in the
             network. The R99 core network includes the equipment such as MSC/VLR, IWF,
             SGSN, GGSN, HLR/AuC and EIR. To support 3G services, the corresponding
             interface protocols are added to some equipment and the original interface protocols
             are improved.
             Figure 3-5 shows the basic network structure of PLMN (including the CS domain and
             the PS domain). All function entities in the figure can be regarded as independent
             physical devices.




2004-08-24                          Confidential Information of Huawei. No                 Page3-8, Total19
                                       Spreading without Permission
                                                                                                                    Error! Use the Home tab to
                                                                                                                apply 标题 1 to the text that you
       Basic Principles of WCDMA System                                                                                    want to appear here.


                                              PSTN                                      Gi                 Gp




                                           GMSC                                    GGSN



                                                          AuC
                                                                       Gc
                                                     C         H

                                                          HLR                                 Gn
                                PSTN   PSTN

                                                                          Gr
                                                     D        EIR

                                                          F          Gf
                           G
               VLR                     VLR
                                                               Gs
                   B                   B                                                SGSN
             MSC                           MSC
                            E

                                                                                                                        CN

                                              A          Gb               IuCS                         IuPS

                        BSS                                                                                       RNS
                                                                                                                      Iur
                                           BSC                                                     RNC                          RNC
                                       Abis                                                        Iubis

                                BTS               BTS                             Node B                   Node B
                                                                                 cell

                       Um                                                          Uu


                                                                            ME

                                                          SIM-ME i/f        or           Cu


                                                                    SIM            USIM

                                                                                              MS




      Bold lines indicate the interfaces to support user services while slim lines indicate the interfaces to support signaling
                                              Figure 3-5 Structure of the R99 network


              In R99, the function entities of the CS domain include MSC, VLR and others. According
              to the different connection modes, an operator can set MSC as GMSC, SM-GMSC or
              SM-IWMSC. To implement internetworking, IWF (usually working with MSC) is
              configured in the system.
              Besides the above function entities, the specific function entities of the PS domain
              include SGSN and GGSN to provide packet data services for subscribers. HLR, AuC
              and EIR are the common devices shared by the CS domain and the PS domain.
              The main function entities of R99 include:
2004-08-24                                 Confidential Information of Huawei. No                                             Page3-9, Total19
                                              Spreading without Permission
                                                                            Error! Use the Home tab to
                                                                        apply 标题 1 to the text that you
       Basic Principles of WCDMA System                                            want to appear here.

             1)   Mobile Switching Center (MSC)
             MSC is specific to the CS domain to connect the radio systems (including BSS and
             RNS) and the fixed network. It implements all functions of CS calls, for example,
             controlling call proceeding, managing the communication services of MS within this
             network or other networks (PSTN/ISDN/PSPDN and other mobile networks), and
             providing charging information.
             2)   Visitor Location Register (VLR)
             VLR is also specific to the CS domain. It stores the information of the registered
             subscribers that enter the control area, so as to provide necessary data of call
             connection of mobile subscribers. When an MS roams to a new VLR area, this VLR will
             initiate the location registration procedure to HLR and get the necessary subscriber
             data; however, when the MS leaves this control area, the subscriber data should be
             deleted. Therefore, VLR can be regarded as a dynamic database.
             A VLR can manage several MSCs, but usually in implementation, MSC and VLR are
             combined.
             3)   Home Location Register (HLR)
             HLR is a device shared by the CS domain and the PS domain, responsible for
             managing the database system of mobile subscribers. PLMN can contain one or more
             HLRs, and the detailed configuration mode is determined by subscriber quantity,
             system capacity and network structure. All mobile subscriber data of the home location
             area, for example, identity flags, location information and subscribed services, are
             stored in the HLR.
             When a subscriber roams, HLR receives the new location information and requests the
             previous VLR to delete all data of the subscriber. When a subscriber is called, HLR will
             provide the routing information.
             4)   Authentication Center (AuC)
             AuC is a device shared by the CS domain and the PS domain to store the entity of
             subscriber authentication algorithm and ciphering key. AuC sends authentication and
             ciphering data to VLR, MSC and SGSN through HLR, to ensure the legality and
             security of communication. Each AuC associates with the corresponding HLR, and it
             communicates with others only through this HLR. Usually, AuC and HLR are combined
             in the same physical entity.
             5)   Equipment Identification Register (EIR)
             EIR is a device shared by the CS domain and the PS domain. It stores the International
             Mobile Equipment Identity (IMEI) of mobile devices used by the system. The mobile
             devices are divided into three levels: white, gray and black, and they are stored in the
             corresponding lists respectively. Nowadays, the EIR is not yet used in China.
             A minimized EIR can only contain the smallest “white list” (the device is in the white
             level).
             6)   Gateway MSC (GMSC)
             SMSC is the specific device of CS domain. GMSC, As the interface between the
             system and other public communication networks, has the function of querying location
             information. When an MS is called, if the network cannot be sure to which HLR the
             subscriber belongs, it should query the HLR through GMSC, and then forwards the call
             to the current registered MSC of the MS.
             Specifically, operators can decide which MSCs (e.g. part of MSCs or all MSCs) can be
             taken as GMSCs,.
             7)   Serving GPRS Support Node (SGSN)


2004-08-24                     Confidential Information of Huawei. No                Page3-10, Total19
                                  Spreading without Permission
                                                                                 Error! Use the Home tab to
                                                                             apply 标题 1 to the text that you
       Basic Principles of WCDMA System                                                 want to appear here.

             SGSN is a piece of equipment specific to the PS domain, and it provides the connection
             between CN and BSS/RNS of the radio access system. In CN, SGSN and
             GGSN/GMSC/HLR/EIR/SCP have the corresponding interfaces. SGSN implements
             the mobility management and session management of packet data services. It
             manages the mobile and communication services of each MS within the mobile
             network, and provides the charging information.
             8)    Gateway GPRS Supporting Node (GGSN)
             GGSN is also a piece of equipment specific to the PS domain. As the interface between
             the mobile communication system and other public data networks, it has the function of
             querying location information. When an MS is called, first the data is transmitted to
             GGSN, then GGSN queries the current location information from HLR and forwards the
             call to the current registered SGSN. GGSN also provides the charging interface.
             The interface protocols of the R99 core network are shown in Table 3-1.

                               Table 3-1 Interface names and meanings of the R99 core network
                   Interface name                   Connection entity              Signaling and protocol
              A                           MSC-BSC                             BSSAP
              Iu-CS                       MSC-RNS                             RANAP
              B                           MSC-VLR
              C                           MSC-HLR                             MAP
              D                           VLR-HLR                             MAP
              E                           MSC-MSC                             MAP
              F                           MSC-EIR                             MAP
              G                           VLR-VLR                             MAP
              Gs                          MSC-SGSN                            BSSAP+
              H                           HLR-AuC
                                          MSC-PSTN/ISDN/PSPDN                 TUP/ISUP
              Ga                          GSN-CG                              GTP'
              Gb                          SGSN-BSC                            BSSGP
              Gc                          GGSN-HLR                            MAP
              Gd                          SGSN-SMS-GMSC/IWMSC                 MAP
              Ge                          SGSN-SCP                            CAP
              Gf                          SGSN-EIR                            MAP
              Gi                          GGSN-PDN                            TCP/IP
              Gp                          GSN-GSN (Inter PLMN)                GTP
              Gn                          GSN-GSN (Intra PLMN)                GTP
              Gr                          SGSN-HLR                            MAP
              Iu-PS                       SGSN-RNC                            RANAP

3.3.2 Structure and Interface of the R4 Network

             Figure 3-6 shows the basic network structure of the PLMN in R4 version. All function
             entities in the figure can be regarded as independent physical devices. The standards
             of Nb, Mc and Nc interfaces are included in 23.205 and 29 series of technical
             specifications.
             In actual application, some functions may be combined into the same physical entity,
             such as MSC/VLR and HLR/AuC, to make some interfaces become internal interfaces.




2004-08-24                          Confidential Information of Huawei. No                 Page3-11, Total19
                                       Spreading without Permission
                                                                                                                             Error! Use the Home tab to
                                                                                                                         apply 标题 1 to the text that you
       Basic Principles of WCDMA System                                                                                             want to appear here.

                                                    PSTN                                         Gi                 Gp
                         PSTN PSTN



                                   CS-        Mc
                                                    GMSC                                     GGSN
                                   MGW              server

                                                               C
                                                                                Gc

                                                     Nc            HLR            AuC
                        PSTN
                                                                             H                        Gn
                                         Nb
                                                                                     Gr
                                                           D         EIR
                               G                               F                Gf
                VLR                      VLR
                               E              B                        Gs
                    B
                                                                                                 SGSN
       MSC server          Nc
                                         MSC server
                                          Mc
               Mc
                                                                                                                                    CN
       CS-MGW                  CS-MGW
                         Nb
                                          A
                                                      Gb
                                                                                     IuCS                        IuPS

                          BSS                                                                                             RNS
                                                                                                                              Iur
                                              BSC                                                          RNC                            RNC
                                          Abis                                                             Iub

                                   BTS               BTS                                   Node B                   Node B
                                                                                          cell


                          Um                                                                Uu


                                                                                     ME

                                                                   SIM-ME i/f        or          Cu


                                                                            SIM             USIM

                                                                                                      MS


      Bold lines indicate the interfaces to support user services while slim lines indicate the interfaces to support signaling
                                                    Figure 3-6 Structure of the R4 network


               Note:
              (G) MSC Server and MGW can be integrated into a single physical entity - (G) MSC.

              In R4 version, the function entities (SGSN and GGSN) of the PS domain remain
              unchanged and so do the external interfaces. The function entities of the CS domain
              still contain the following devices: MSC, VLR, HLR, AuC, EIR and so on, and the
              interrelation between them does not change yet. To meet the development requirement


2004-08-24                                        Confidential Information of Huawei. No                                                 Page3-12, Total19
                                                     Spreading without Permission
                                                                            Error! Use the Home tab to
                                                                        apply 标题 1 to the text that you
       Basic Principles of WCDMA System                                            want to appear here.

             of all-IP networks, the entities of the CS domain in R4 version have the following
             changes:
             1.   When necessary, the MSC can be divided into two different entities: MSC Server
                  (for processing signaling only) and Circuit Switched Media Gateway (CS-MGW for
                  processing subscriber data) to implement the MSC function together. The
                  corresponding GMSC is also divided into GMSC Server and CS-MGW.
             1)   MSC Server
             The MSC Server is composed of the call control module and the mobility control
             module to process calls of the CS domain. It terminates and converts the user-network
             signaling into the network-network signaling. It can also contain VLR to process service
             data of mobile subscribers and the related CAMEL data.
             The MSC Server can control part of call status about the connection control module of
             the CS-MGW media channel through interfaces
             2)   Circuit Switched Media Gateway (CS-MGW)
             CS-MGW is the transmission termination point of PSTN/PLMN, and it connects with
             CN and UTRAN through the Iu interface. It may be the termination point of either the
             bearer channel from the CS network or the media flow from the packet network (such
             as RTP flow in IP networks). On the Iu interface, CS-MGW can support media
             conversion, bearer control and payload processing (for example, multi-media digital
             signal codec, echo cancellation and conference bridge), and also can support different
             Iu options of CS services (based on AAL2/ATM or RTP/UDP/IP).
             CS-MGW:
                 Connecting with MSC server and GMSC server to control resources
                 Owning and using such resources as echo canceller
                 Can be equipped with a multimedia digital signal codec
             CS-MGW may have necessary resources to support UMTS/GSM transport media.
             Furthermore, it can require the H.248 tailor to support multimedia digital signal codec
             and framing protocol.
             The bearer control module and payload processing capability of CS-MGW can be used
             to support such mobility functions as SRNS reallocation/handover and location
             services. Nowadays, it is expected that the H.248 standard mechanism can be used to
             support these functions.
             3)   GMSC Server
             The GMSC Server is composed of the call control module and the mobility control
             module of GMSC.
             2.   HLR can be updated to become a Home Subscriber Server (HSS). For details,
                  please refer to the R5 network introduction.
             3.   In R4, a new entity has been added: Signaling Gateway (SGW)
             There are two kinds of singalling transport methods: TDM based tradictional SS7 and
             IP based siganlling transport network SIGTRAN.
             A siganlling gateway is needed to convert the transport layer protocol (i.e. between
             Sigtran SCTP/IP and SS7 MTP) when two equipments communicate using different
             signalling transport method. The SGW does not interpret the application layer (e.g.
             MAP, CAP, BICC, ISUP) messages but may have to interpret the underlying SCCP or
             SCTP layer to ensure proper routing of the signaling.
             In R4 networks, some interface protocols are also added, as shown in Table 3-2.


2004-08-24                     Confidential Information of Huawei. No                Page3-13, Total19
                                  Spreading without Permission
                                                                                 Error! Use the Home tab to
                                                                             apply 标题 1 to the text that you
       Basic Principles of WCDMA System                                                 want to appear here.

                               Table 3-2 Names and meanings of external interfaces in R4 CN
                  Interface name                Connection entity                   Signaling and protocol
             A                         MSC-BSC                              BSSAP
             Iu-CS                     MSC-RNS                              RANAP
             B                         MSC-VLR
             C                         MSC-HLR                              MAP
             D                         VLR-HLR                              MAP
             E                         MSC-MSC                              MAP
             F                         MSC-EIR                              MAP
             G                         VLR-VLR                              MAP
             Gs                        MSC-SGSN                             BSSAP+
             H                         HLR-AuC
                                       MSC-PSTN/ISDN/PSPDN                  TUP/ISUP
             Ga                        SGSN-CG                              GTP'
             Gb                        SGSN-BSC                             BSSGP
             Gc                        GGSN-HLR                             MAP
             Gd                        SGSN-SM-GMSC/IWMSC                   MAP
             Ge                        SGSN-SCP                             CAP
             Gf                        SGSN-EIR                             MAP
             Gi                        GGSN-PDN                             TCP/IP
             Gp                        GSN-GSN (Inter PLMN)                 GTP
             Gn                        GSN-GSN (Intra PLMN)                 GTP
             Gr                        SGSN-HLR                             MAP
             Iu-PS                     SGSN-RNC                             RANAP
             Mc                        (G) MSC Server-CS-MGW                H.248
             Nc                        MSC Server-GMSC Server               BICC/ ISUP/TUP
             Nb                        CS-MGW-CS-MGW
             Mh                        HSS-R-SGW




2004-08-24                         Confidential Information of Huawei. No                     Page3-14, Total19
                                      Spreading without Permission
                                                                                                                             Error! Use the Home tab to
                                                                                                                         apply 标题 1 to the text that you
       Basic Principles of WCDMA System                                                                                             want to appear here.

3.3.3 Structure and Interface of the R5 Network

                           Alternative                                                           Legacy mobile
                                                         Applications &                            signaling
                             Access                       Services *)                              Network
                            Network
                                                           SCP
                                                                                                                                           Multimedia
                                                                                                                         CSCF
                                                                                                      R-SGW                               IP Networks
                                                                                 Mh                            Mw
                                         SGSN                                                     Ms
                GGSN                                       CAP
                                                                                                                           Mm
                                          Gn                        HSS *)             Cx
             Other PLMN                                                                           CSCF
                                                                      Gr                                            Mg
                                            Gp                                              Gi            Mr                    Gi
                                                                     EIR
                                                                                                        MRF
                                          ERAN
                                                                           Gf
                  TE          MT                                                      Gc                  Gi             MGCF         T-SGW *)
                       R            Um         Iu-ps'
                                                                      SGSN                            GGSN                      Mc
                                                    Iu                                                           Gi
                                                                                       Gn
                                                                1
                                                          Iu                                                                                 PSTN/
                 TE          MT          UTRAN                                                                           MGW
                                                                       MGW                                                               Legacy/External
                       R            Uu                                                       Nb
                                                         Iu 2                   Mc                                          Mc
                   1
                 Iu = Iucs (RTP, AAL2)
                                                                                                 Nc
                   2                                                MSC server                                GMSC server             T-SGW *)
                 Iu = Iu(RANAP)

                                                                                                               MAP
                                                                                 MAP                     Mh
                                           Applications
                                           & Services *)                                   HSS *)                R-SGW *)


                                                                                                          *) those elements are duplicated for figure
             Signalling Interface
                                                                                                         layout purpose only, they belong to the same
             Signalling and Data Transfer Interface                                                      logical element in the reference model


      Bold lines indicate the interfaces to support user services while slim lines indicate the interfaces to support signaling
                                                 Figure 3-7 Structure of the R5 network


               Note:
              (G)MSC Server and MGW can be integrated into a single physical entity (G)MSC.

              The structure and interface format of R5 version networks is basically the same as that
              of R4 networks. However, there are still some differences: In R5, when PLMN includes
              the IM subsystem, HLR will be replaced by HSS. Furthermore, the A and Iu-CS
              interfaces are supported simultaneously between BSS, CS-MSC/MSC-Server, and the
              Gb and Iu-PS interfaces are supported between BSC and SGSN.
              For simplicity, R5 interface protocols will not be described here.
              Figure 3-8 shows the basic network structure of the IMS in R5 version, where the
              function entities and Interfaces of the IMS domain are indicated. All function entities in
              the figure can be regarded as independent physical devices. For detail description
              please refer to R5 23.002 specification.




2004-08-24                                  Confidential Information of Huawei. No                                                        Page3-15, Total19
                                               Spreading without Permission
                                                                                                    Error! Use the Home tab to
                                                                                                apply 标题 1 to the text that you
       Basic Principles of WCDMA System                                                                    want to appear here.


                                   IP Multimedia Networks                                             Legacy mobile
                                          PSTN                                                        signalling Networks

                          Mb      Mb         PSTN
                                                          BGCF                      CSCF
                                             PSTN                                               Mm
                                                                   Mk          Mk

                                                                                          Mw
                                                                                                                C, D,
                                                         Mj       BGCF                                          Gc, Gr
                                                                                Mi
                                                                                                 Cx
                                       IMS-   MGCF                                                        HSS
                                       MGW Mn                      Mg               CSCF

                                                                     Mr              Mw          Dx       SLF
                                        Mb

                                                                           P-CSCF
                               MRFP                 MRFC            PDF                              UE
                                                                                           Gm
                                             Mp
                                                                                                      IM Subsystem
                          Mb       Mb        Mb                           Go




             Bold lines indicate the interfaces to support user services while slim lines indicate the interfaces to support signaling
                                                Figure 3-8 Structure of the R5 IMS network


              Note:
             The Gm interface between CSCF and UE is also an interface of the IM subsystem. But due to the layout, it
             is not indicated in the Figure.

             The following function entities are added to R5:

             1. Home Subscriber Server (HSS)

             With the IM subsystem, the network should use HSS instead of HLR.
             HSS is the main database of mobile subscribers in the network and stores the related
             service information to support the call/session processing by the network entities. For
             example, through authentication, authorization, name/address resolution and location
             dependency, HSS supports the call control server to implement smoothly such
             procedures as roaming/routing.
             Similar to HLR, HSS should maintain and manage such subscriber-related information
             as subscriber identity, address, security, location and subscription services. Based on
             this information, HSS can support the CC/SM entity of different control systems (CS
             domain control system, PS domain control system and IM control system). Its basic
             structure and interfaces are shown in Figure 3-9.




2004-08-24                             Confidential Information of Huawei. No                                     Page3-16, Total19
                                          Spreading without Permission
                                                                                      Error! Use the Home tab to
                                                                                  apply 标题 1 to the text that you
       Basic Principles of WCDMA System                                                      want to appear here.



                                                           HSS


                                    Subscription           Location
                                    information            information




                           D          C            Gr            Gc          Cx




                       MSC Server GMSC Server       SGSN              GGSN        CSCF




                                    Figure 3-9 Basic structure and interface of HSS


             HSS can integrate different kinds of information to enhance the service support of
             application and service domain from the core network, as well as shielding different
             types of network structures from the upper layer. It supports the following functions:
             Subscriber control function requested by the IM subsystem, related HLR function
             subset requested by the PS domain and HLR function of the CS domain (in case that
             subscribers are allowed to access the CS domain, or roam to the traditional networks)

             2. Call Status Control Function (CSCF)

             CSCF has the following forms: Proxy CSCF (P-CSCF), Serving CSCF(S-CSCF) or
             Interrogating CSCF (I-CSCF):

             P-CSCF: Serves as the first access point of UE in the IM sub-system.
             S-CSCF: Processes the session status in the network.
             I-CSCF: Mainly process the route related SIP call request, just like the GMSC function
               in CS domain.
             The Policy Decision Function (PDF) is a logical entity of the P-CSCF. If the PDF is
             implemented in a separate physical node, the interface between the PDF and the
             P-CSCF is not standardised.



             3. Media Gateway Control Function (MGCF)
                Controlling part of calling status of the connection control module in the IMS-MGW
                 media channel
                Communicating with CSCF
                Selecting CSCF according to the call routing numbers from traditional networks
                Converting the call control protocols between ISUP and the IM subsystem
                Receiving out-band information and forwarding it to CSCF/IMS-MGW
             4. IP Multimedia Subsystem-Media Gateway (IMS-MGW)

             A IMS-MGW may terminate bearer channels from a switched circuit network and media
             streams from a packet network (e.g., RTP streams in an IP network). The IMS-MGW

2004-08-24                     Confidential Information of Huawei. No                          Page3-17, Total19
                                  Spreading without Permission
                                                                            Error! Use the Home tab to
                                                                        apply 标题 1 to the text that you
       Basic Principles of WCDMA System                                            want to appear here.

             may support media conversion, bearer control and payload processing (e.g. codec,
             echo canceller, conference bridge),.
             IMS-MGW implements the following functions:
                Interacts with the MGCF for resource control.
                Owns and handles resources such as echo cancellers etc.
                May need to have codecs.
             The IMS-MGW will be provisioned with the necessary resources for supporting
             UMTS/GSM transport media. Further tailoring (i.e. packages) of the H.248 may be
             required to support additional codecs and framing protocols, etc.

             5. Multimedia Resource Function Controller (MRFC)

             The MRFC:
                Controls the media stream resources in the MRFP.
                Interprets information coming from an AS and S-CSCF (e.g session identifier) and
                 control MRFP accordingly.
                Generates CDRs .
             6. Multimedia Resource Function Processor (MRFP)

             The MRFP:
                Controls bearers on the Mb reference point.
                Provides resources to be controlled by the MRFC.
                Mixes incoming media streams (e.g. for multiple parties).
                Sources media streams (for multimedia announcements).
                Processes media streams (e.g. audio transcoding, media analysis).
             7. Subscription Locator Function (SLF)

             The SLF:
                Is queried by the I-CSCF during the Registration and Session Setup to get the
                 name of the HSS containing the required subscriber specific data. Furthermore
                 the SLF is also queried by the S-CSCF during the Registration.
                Is accessed via the Dx interface
             The SLF is not required in a single HSS environment. An example for a single HSS
             environment is a server farm architecture.

             8. Breakout Gateway Control Function (BGCF)

             The Breakout Gateway control function (BGCF) selects the network in which PSTN/CS
             Domain breakout is to occur. If the BGCF determines that the breakout is to occur in the
             same network in which the BGCF is located within, then the BGCF shall select a MGCF
             which will be responsible for the interworking with the PSTN/CS Domain. If the break
             out is in another network, the BGCF will forward this session signalling to another
             BGCF in the selected network.
             The functions performed by the BGCF are:
                Receives request from S-CSCF to select appropriate PSTN/CS Domain break out
                 point for the session
                Select the network in which the interworking with the PSTN/CS Domain is to occur.
                 If the interworking is in another network, then the BGCF will forward the SIP
                 signalling to the BGCF of that network. If the interworking is in another network
                 and network hiding is required by the operator, the BGCF will forward the SIP
                 signaling via an I-CSCF(THIG) toward the BGCF of the other network.
2004-08-24                     Confidential Information of Huawei. No                Page3-18, Total19
                                  Spreading without Permission
                                                                           Error! Use the Home tab to
                                                                       apply 标题 1 to the text that you
       Basic Principles of WCDMA System                                           want to appear here.

                Select the MGCF in the network in which the interworking with PSTN/CS Domain
                 is to occur and forward the SIP signalling to that MGCF. This may not apply if the
                 interworking is a different network.
                Generation of CDRs.
             The BGCF may make use of information received from other protocols, or may make
             use of administrative information, when making the choice of which network the
             interworking shall occur.




2004-08-24                    Confidential Information of Huawei. No                Page3-19, Total19
                                 Spreading without Permission

				
DOCUMENT INFO