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997ad2510cb826711e63f644e1d2617f | 23.873 | 6.2.1.3 PS Media Gateway (PS-MGW) | The PS-MGW handles the user plane for GPRS. It terminates the GTP-U tunnels towards the GGSN over the Gn and Gp interfaces and towards the RNC over the Iu interface.
The relation between the SGSN server and the PS-MGW represents the architectural association between a master and a slave, respectively. Therefore, this a... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.2.2 Interfaces | Only interfaces for which some clarification is felt useful are mentioned in this section. Interfaces that are not described here conform to their definition in the relevant specifications.
The protocols GTP-U, GTP-C, RANAP and BSSGP referred to in the following subclauses conform to their current specifications and ar... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.2.2.1 SGSN server – PS-MGW (Mp) (Iu Mode Only) | The PS-MGW is controlled by the SGSN server through the Mp interface. |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.2.2.2 UTRAN – SGSN server (Iu) (Iu Mode Only) | The Iu interface between the RNC and the SGSN server supports the RANAP protocol. |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.2.2.3 UTRAN – PS-MGW (Iu) (Iu Mode Only) | The Iu interface between the RNC and the PS-MGW supports the GTP-U protocol. |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.2.2.4 BSS – 2G-SGSN (Gb) (Gb Mode Only) | The Gb interface between the BSS and the 2G-SGSN supports the BSSGP protocol. This interface belongs to both to the user and control planes. |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.2.2.5 2G-SGSN/SGSN server – GGSN (Gn, Gp) | In Iu mode, the Gn interface between the SGSN server and the GGSN supports the GTP-C protocol.
In Gb mode, the interface between the 2G-SGSN and the GGSN supports the GTP-C protocol in the control plane and the GTP-U protocol in the user plane.
The Gp interface provides the same functionality as the Gn interface, excep... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.2.2.6 PS-MGW – GGSN (Gn) (Iu Mode Only) | The Gn interface between the PS-MGW and the GGSN supports the GTP-U protocol. |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.2.2.7 Gn interface for inter SGSN procedures | At inter SGSN intersystem change (UMTS to/from GSM):
- the Gn interface between the SGSN server and the 2G-SGSN supports the GTP-C protocol.
- the Gn interface between the 2G-SGSN and the PS-MGW controlled by the peer SGSN server supports the GTP-U protocol.
When the MS moves between GSM cells served by two different 2... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.2.3 User plane | The protocol stack for the user plane is shown in figure 3.
Figure 3: User plane protocol stack |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3 H.248 option over Mp | NOTE: Two options are considered in this TR as to the protocol to use over the Mp interface; H.248 with extensions and GTP-C with extensions. Both options are described for comparison purposes, however only one of them shall eventually be retained. The protocol selection might be deferred to the stage 3 work. |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.1 Mobility Management (H.248 option) | |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.1.1 Detach Procedures | The detach procedure can be initiated by the MS, by the SGSN and by the HLR. The latter two sequences are omitted in this description as they are similar to the first sequence, and they do not add any complexity to the detach sequences.
Figure 4: MS-Initiated Combined PS/CS Detach Procedure
1) The MS detaches by sendin... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.1.2 Routing Area Update Procedure | The Iu connection is not active in the RA update procedure shown here. If the MS is in PMM-connected state, the SRNS relocation procedure would take place. After a SRNS relocation procedure is performed, a simplified RA update procedure would take place.
Figure 5: UMTS RA Update Procedure
1) The MS sends a Routeing Are... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.1.3 Serving SRNS Relocation Procedure | Figure 6: Serving SRNS Relocation procedure
1) The source SRNC decides to perform/initiate a SRNS relocation.
2) The source SRNC initiates the relocation preparation procedure by sending a Relocation Required message to the old SGSN server.
3) The old SGSN server determines from Target ID if the SRNS Relocation is intr... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.1.4 UMTS to GSM Intra SGSN Change | Figure 7: UMTS to GSM Intra SGSN Change
1) The MS or BSS or UTRAN decides to perform an intersystem change, which makes the MS switch to a new cell that supports GSM radio technology, and stops transmission to the network.
2) The MS sends a Routeing Area Update Request message to the 2G‑SGSN+SGSN server.
3) The 2G‑SGSN... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.1.5 GSM to UMTS Intra SGSN Change | Figure 8: GSM to UMTS Intra SGSN Change
1) The MS or BSS or UTRAN decides to perform an intersystem change, which makes the MS switch to a new cell that supports UMTS radio technology, and stops transmission to the network.
2) The MS sends a Routeing Area Update Request message to the 2G-SGSN+SGSNserver. The 2G-SGSN+SG... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.1.6 UMTS to GSM Inter SGSN Change | Figure 9: UMTS to GSM Inter SGSN Change
1) The MS or BSS or UTRAN decides to perform an intersystem change, which makes the MS switch to a new cell that supports GSM radio technology, and stops transmission to the network.
2) The MS sends a Routeing Area Update Request message to the new 2G‑SGSN.
3) The new 2G‑SGSN sen... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.1.7 GSM to UMTS Inter SGSN Change | Figure 10: GSM to UMTS Inter SGSN Change
1) The MS or BSS or UTRAN decides to perform an intersystem change, which makes the MS switch to a new cell that supports UMTS radio technology, and stops transmission to the network.
2) The MS sends a Routeing Area Update Request message to the new SGSN server.
3) The new SGSN ... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.2 Session Management (H.248 option) | |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.2.1 PDP Context Activation Procedure | Figure 11: PDP Context Activation Procedure for UMTS
1) The MS sends an Activate PDP Context Request (NSAPI, TI, PDP Type, PDP Address, Access Point Name, QoS Requested, PDP Configuration Options) message to the SGSN server.
2) The SGSN server validates the Activate PDP context request message. The SGSN server may rest... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.2.2 Secondary PDP Context Activation Procedure | The Secondary PDP Context Activation procedure may be used to activate a PDP context while reusing the PDP address and other PDP context information from an already active PDP context.
Figure 12: Secondary PDP Context Activation Procedure for UMTS
1) The MS sends an Activate Secondary PDP Context Request (Linked TI, NS... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.2.3 Network-Requested PDP Context Activation Procedure | The Network-Requested PDP Context Activation procedure allows the GGSN to initiate the activation of a PDP context. This procedure is a request in the control plane towards the MS to initiate a PDP Context Activation procedure. The PDP Context Activation procedure itself is performed as shown above in Section . Therefo... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.2.4 PDP Context Modification Procedures | The following parameters can be modified in a PDP context modification procedure:
- QoS Negotiated;
- Radio Priority;
- Packet Flow Id;
- PDP Address (in case of the GGSN-initiated modification procedure); and
- TFT (in case of MS-initiated modification procedure).
Of these parameters, only the modification of the QoS ... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.2.5 PDP Context Deactivation Procedure | PDP context deactivation can be initiated by the MS, by the SGSN and by the GGSN. The latter two sequences are omitted in this description as they are similar to the first sequence, and they do not add any complexity to the deactivation sequences.
Figure 14: PDP Context Deactivation Initiated by MS Procedure for UMTS
1... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.2.6 Iu Release Procedure | Figure 15: Iu Release Procedure
1) The RNC sends an Iu Release Request message to the SGSN server.
2) The SGSN server sends the “MODIFY Request” message to the PS-MGW to remove the TEID(s) and the IP address(es) that the PS-MGW requires for communication towards the RNC. The maximum bit rate is included in this message... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.2.7 Service Request Initiated by MS Procedure | Figure 16: Service Request Initiated by MS Procedure
1) The MS establishes an RRC connection if none exists for CS traffic.
2) The MS sends a Service Request message to the SGSN server.
If Service Type indicates Data, then a signalling connection is established between the MS and the SGSN server, and resources for acti... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.2.8 Service Request Initiated by Network Procedure | Figure 17: Service Request Initiated by Network Procedure
1) The PS-MGW receives a downlink PDP PDU for an MS in PMM‑IDLE state.
2) The PS-MGW sends the “NOTIFY” message to the SGSN server to indicate that the previously set Event (inform upon reception of downlink PDP PDU) is encountered for the PDP context.
3) The SG... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.3 Charging (H.248 option) | Today there is no requirement on spatial accuracy of charging data. However, such a requirement is easily remedied by letting the SGSN server read from the PS-MGW the data belonging to one area and to reset the counting and the Event when moving between areas. This can be done by means of existing H.248 mechanisms.
NOT... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.3.1 Handling of S-CDR | The data handled in the S-CDR are both based on control plane layer functionality (e.g. control layer signalling parameters) and user plane traffic (e.g. transferred volume).
The PS-MGW will transfer the parameters contained within the user plane to the SGSN server when required (Event based). The list of traffic data ... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.3.2 Handling of other types of CDRs in the SGSN server | The other types of CDRs handled by SGSN are:
- M-CDR
- S-SMO-CDR
- S-SMT-CDR
These contain only data from control signalling messages and data that is stored in the SGSN server. Therefore these CDRs are handled in the SGSN server. |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.3.3 Handling of prepaid on-line | Prepaid on-line charging is always CAMEL based for GPRS. Since the CAMEL based charging will be Event based on the Mp interface, the charging information will be reported in real time to the SGSN server. For this reason, prepaid does not add any complexity to the split of the SGSN, but requires fast processing. See cha... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.3.4 Handling of hot-billing | Hot-billing is CDR based charging in GPRS, with the additional requirement of being able to output the CDRs relatively quickly. Since the CDR based charging will be Event based on the Mp interface, the charging data will be reported in real time to the SGSN server. For this reason, hot-billing does not add any complexi... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.3.5 General charging issues on the Mp interface | Charging data will be reported from the PS-MGW to the SGSN server per PDP context, and it is possible to set thresholds for when to do this reporting. In order not to overload the Mp interface, it is important to take some caution when setting the conditions for reporting. However, as the thresholds are set from the SG... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.4 CAMEL Considerations (H.248 option) | |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.4.1 Handling of Volume Based CAMEL Charging | For CAMEL, the SCF has the possibility to individually set both a volume threshold and a time threshold on PDP context level. The time threshold gives a relative time for when to report back to the SCF, while the volume threshold gives a number of octets (in the user plane packets) to monitor for before reporting back ... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.4.2 Handling of Time Based CAMEL Charging | Thresholds for time based CAMEL charging on PDP context level will be possible to monitor in the PS-MGW, as this threshold is closely connected to the volume threshold supplied from the SCF (via the SGSN server). Alternatively, this time monitoring is possible to perform from the SGSN server as described in the previou... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.5 Lawful Interception (H.248 option) | |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.5.1 Lawful Interception of Content of Communications | To enable the PS-MGW to intercept Content of Communication (CC), or in other words user plane packets, and forward these to Delivery Function 3 (DF3), the SGSN server must order the PS-MGW to set up a one way connection towards DF3 for every applicable PDP Context. The SGSN server must give the PS-MGW the parameters th... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.5.2 Lawful Interception of Intercept Related Information | The IRI (Intercept Related Information) is control layer signalling, and therefore this must be handled in the SGSN server. |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.6 QoS Considerations (H.248 option) | The QoS aspects in the split architecture when the resource situation is of no concern are already handled in Mobility Management and Session Management.
The PS-MGW should inform its SGSN server(s) about the load situation in the PS-MGW. Work is ongoing in H.248 standardisation to solve the issues of overload and con... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.3.7 Abnormal Cases (H.248 option) | Existing procedures will be used as far as possible. In the H.248 standardisation area, the PS domain of 3GPP should take advantage of existing work ongoing in the CS domain of 3GPP. More specific this means the following:
The Echo Request and the Echo Response messages will be used to discover link failure between use... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.4 GTP-C option over Mp | NOTE: Two options are considered in this TR as to the protocol to use over the Mp interface; H.248 with extensions and GTP-C with extensions. Both options are described for comparison purposes, however only one of them shall eventually be retained. The protocol selection might be deferred to the stage 3 work. |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.4.1 Mobility Management (GTP-C option) | The SGSN split does not have effects on the Mobility Management procedures for attach and detach, security and subscriber management. The location management procedures (i.e. the routing area update and the serving SRNS relocation procedures) and the Service Request procedures are affected. The changes are not major. T... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.4.1.1 Routing Area Update Procedure | At inter SGSN routing area update, the PDP context information is transferred from the old SGSN Server to the new SGSN Server. The PS-MGW may be changed or preserved.
If the PS-MGW is changed, the PDP contexts are created in the new PS-MGW and deleted in the old PS-MGW. The inter SGSN routing area update procedure with... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.4.1.2 Serving SRNS Relocation Procedure | If the SGSN Server is changed at serving SRNS relocation, the PDP context information is transferred from the old SGSN Server to the new SGSN Server. The PS-MGW may be changed or preserved.
If the PS-MGW is changed, the PDP contexts are created in the new PS-MGW and deleted in the old PS-MGW. The serving SRNS relocatio... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.4.2 Session Management (GTP-C option) | Session Management is used for PDP context activation, modification and deactivation. All the procedures are affected by the SGSN split. The changes are not major. The traffic in the backbone network is, however, increased due to signalling between the SGSN Server and the PS-MGW. |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.4.2.1 PDP Context Activation Procedure | At PDP context activation, a PDP context is created in the PS-MGW. The PDP context is needed in the PS-MGW, e.g., to relay GTP-U packets between the RNC and the GGSN and to provide the negotiated QoS. The SGSN Server selects the PS-MGW to which the PDP context is created. The selection may be static (i.e. the SGSN Serv... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.4.2.2 PDP Context Modification Procedures | At PDP context modification, the PDP context in the PS-MGW is updated.
The MS initiated PDP context modification procedure with the required changes is presented in the figure below. The required changes are the same in case of the SGSN or GGSN initiated PDP context modification procedure.
Figure 24: MS-Initiated PDP C... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.4.2.3 PDP Context Deactivation Procedure | At PDP context deactivation, the PDP context in the PS-MGW is deleted.
The MS initiated PDP context deactivation procedure with the required changes is presented in the figure below. The required changes are the same in case of the SGSN or GGSN initiated PDP context deactivation procedure.
Figure 25: PDP Context Deacti... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.4.2.4 RAB Release Procedure | With the RAB release procedure, the UTRAN initiates the release of one or more RABs. The SGSN Server has to inform the PS-MGW about the RAB release. The RAB release procedure with the required changes is presented in the figure below.
Figure 26: RAB Release Procedure
1-4) The RAB release procedure is performed as descr... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.4.2.5 Service Request Initiated by MS Procedure | After releasing RABs for active PDP contexts (see chapter ‘RAB release’), it may be necessary to establish the RABs again, e.g., due to packets to be transferred on the PDP contexts. This is done with the service request procedure initiated either by the MS or by the network. The SGSN Server has to inform the PS-MGW ab... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.4.2.6 Service Request Initiated by Network Procedure | The network initiated service request procedure with the required changes is presented in the figure below.
Figure 28: Service Request Initiated by Network Procedure
1) A downlink PDU is received in the PS-MGW.
2) The PS-MGW sends the Update PDP Context Request message to the SGSN Server to request the initiation of pa... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.4.3 Charging (GTP-C option) | |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.4.4 CAMEL Considerations (GTP-C option) | The communication towards the SCP is triggered by signalling events as well as by events related to the transfer of user data. The communication towards the SCP may be provided either by 1) preserving only one interface towards the SCP (i.e. SGSN Server – SCP) and sending the necessary information between the SGSN Serv... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.4.5 Lawful Interception (GTP-C option) | |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.4.5.1 Lawful Interception of Content of Communications | To enable the PS-MGW to intercept Content of Communication (CC), or in other words user plane packets, and forward these to Delivery Function 3 (DF3), the SGSN server must order the PS-MGW to set up a connection towards DF3 for every applicable PDP Context. The SGSN server must give the PS-MGW the parameters that are n... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.4.5.2 Lawful Interception of Intercept Related Information | The IRI (Intercept Related Information) signalling is handled by the SGSN server. |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.4.6 QoS Considerations (GTP-C option) | |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.4.7 Information storage in PS-MGW (GTP-C option) | The PS-MGW has to store information on active PDP contexts in order to relay packets between the RNC and the GGSN. For uplink packets, the PS-MGW needs the GGSN Address for User Plane and the GGSN TEID for User Plane. For downlink packets, the PS-MGW needs the RNC Address for User Plane and the RNC TEID for User Plane.... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.4.8 Abnormal Cases (GTP-C option) | |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.5 General Lawful Interception Considerations | As the protocol interfaces and data formats between the ADMF/DF and GSN entities were omitted from the scope of standardisation, constraints on the interoperability of the split SGSN exist, if the entities are to be supplied from different vendors. The ADMF and DF entities in this case would have to inter-operate with ... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.6 Security | The security mechanisms Ipsec/IKE can be used on the Mp interface. Ipsec/IKE are recommended for the H.248 protocol and are parts of the security architecture that is under design in S3 for the UMTS R4/R5 network. |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.7 O&M | The split SGSN solution will add a new network element to manage but only minor changes to the 3GPP O&M standards. |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.8 RAN Considerations (e.g. GERAN) | No impacts are foreseen between the split of the SGSN and the RAN functionality since:
- The Iu-PS interface is already split into a control plane and a user plane, and the existing protocols can be used as is.
- The Gb interface will be terminated in the 2G-SGSN for both the control plane and the user plane.
- GERAN u... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.9 Compatibility | The compatibility issue between 2G and 3G is already handled in the sections on Mobility Management.
As there is no impact on the existing PS protocols when introducing the split architecture, the SGSN server and the PS-MGW can have an interface towards R’97 (and later releases) nodes, both towards SGSN and GGSN. |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.10 Dynamic Allocation of PS-MGW Resources | A simple way of achieving resource sharing is that each SGSN server uses a primary PS-MGW and a secondary PS-MGW. Say SGSN server A uses PS-MGW A as its primary and PS-MGW B as its secondary, and SGSN server B uses PS-MGW B as its primary and PS-MGW A as its secondary. SGSN server A will therefore use PS-MGW A, and SGS... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.11 Benefits and Drawbacks | The benefits and drawbacks are compared to the R’99 architecture, unless otherwise specified.
Benefits:
- Flexibility to allocate processing capacity for traffic and for control in different locations
- Flexibility to independently scale the control plane and the user plane by increasing/decreasing the number of nodes ... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 6.12 Open Issues | - Investigation into redundancy schemes are to be addressed in stage 3 work
- Comparison analysis of H.248 and GTP-C protocols is to be addressed in stage 3 work
- Migration to MIP Step 3, as proposed by TR 23.923, would negate the need for the split architecture.
- Ongoing 3GPP work on Iu flexibility will allow load s... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7 Alternative 2: One Tunnel Approach | |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.1 Introduction | The One Tunnel Approach separates transport and control functionality of the SGSN in applicable scenarios. The result of this separation are an SGSN controller (cSGSN) performing all control functions of an SGSN and an enhanced GGSN (xGGSN) which performs SGSN and GGSN transport functionality. This enables a direct GTP... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.1.1 Applicability | The benefits of the approaches depend on the extent of their applicability. An anticipation of future IP bearer service usage is therefore important to identify the gain of the approaches.
The trends for the usage of IP bearer services anticipated here are:
- IP based VPN solutions provide access to Intranets in an acc... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.2 Logical Architecture | The logical architecture for this approach, as an evolution of the reference logical architecture, is depicted in Figure 33.
Figure 33: Evolved logical architecture for the One Tunnel Approach |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.2.1 Functional Nodes | Only functional nodes relevant for the One Tunnel Approach are described, i.e. which are changed compared with R99 or used differently. |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.2.1.1 2G-SGSN | This evolved architecture has no impact on the 2G-SGSN or its interfaces. A 2G-SGSN is necessary to support the Gb interface which does not support a separation of transport and control. The Gn interface of a 2G-SGSN supports both user and control data. |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.2.1.2 3G-SGSN / cSGSN | This evolved architecture has no impact on the 3G-SGSN and its interfaces and is compatible with it. A 3G-SGSN is necessary to support packet bearer services using GGSN external to the visited PLMN and packet bearer services using a R97-R99 GGSN.
The 3G-SGSN can be upgraded to become an SGSN without data transport func... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.2.1.3 GGSN / xGGSN | The R99 GGSN can be upgraded to become a GGSN required for the one tunnel approach by adding new functionality and modifying its interface towards the cSGSN. In order to have a differentiation the following notion is introduced.
The notion of an (x)GGSN shall maintain a clear figure of the architecture. The (x)GGSN is ... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.2.2 Interfaces | Only interfaces relevant for the One Tunnel Approach are described, i.e. interfaces which are changed compared with 3GPP R99. |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.2.2.1 Gn (cSGSN – xGGSN) | This interface evolves to control the direct GTP tunnel between RAN and xGGSN and to deliver information for SGSN specific transport functions to the xGGSN (location information and prepaid budget).
The modifications compared with the R99 GTP version are:
- One Tunnel information field is introduced as optional informa... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.2.3 User Plane | The protocol stack for the user plane is shown in Figure 34. The protocol stacks in the UE, in the 3G-RAN and the 3G-GGSN are the same as specified in the 3GPP R99 architecture. The user plane protocols specified for the SGSN are not needed in the One Tunnel Approach. Instead the IP transport network adapts different p... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.3 Mobility Management | The procedures are for packet bearer services using a GGSN in the visited network with a 3G RAN, i.e. for the cSGSN / xGGSN architecture of the One Tunnel Approach. For all other bearer services or 2G RAN the R99 procedures and the SGSN / GGSN as specified in TS 23.060 apply. Modifications compared with 3GPP R99 are in... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.3.1 Inter ISGSN Routeing Area Update | The Inter ISGSN Routeing Area Update procedure is illustrated in Figure 35. The difference compared with 3GPP R99 is in step 5) when the change is from a cSGSN or an SGSN to a cSGSN. In this case the Tunnel Endpoint Identifier delivered to the xGGSN indicates the reserved “not allocated” value for the traffic path as t... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.3.2 Location Report Procedure | This procedure is necessary in order to inform the xGGSN about the location of a subscriber. This is needed e.g. for location dependent interception or location dependent charging.
Figure 36: Location Report Procedure
1) The cSGSN sends a Location Report message to the xGGSN. This could contain the SAI or a geographica... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.3.3 Serving SRNS Relocation Procedure | The Serving SRNS Relocation procedure is illustrated in figure 37. The sequence is valid for both intra cSGSN SRNS relocation and inter cSGSN SRNS relocation. The differences to 3GPP R99 are: in step 4) the RAN is provided with the user data TEID and user data Address of the xGGSN instead that of the SGSN and in step 1... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.3.4 Combined Hard Handover and SRNS Relocation Procedure | With the same modifications as for the SRNS Relocation Procedure above compared to 3GPP R99 this procedure relocates the direct GTP tunnel between RAN and xGGSN from one RNC to the other. |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.3.5 UMTS to GSM Change | In this case the procedure is the same as specified in 23.060 for the R99 UMTS to GSM change. The SRNS Data Forward Command delivers from cSGSN to the SRNC tunnel endpoints for the packets to be forwarded. These tunnels terminate in the cSGSN as in R99. The downlink data flow is then GGSN – SRNC – cSGSN – 2G-SGSN until... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.3.6 GSM to UMTS SGSN Change | The intersystem change from GSM to UMTS takes place when a GPRS-attached UE changes from GSM radio access to UTRAN and the UTRAN node serving the UE is served by a different SGSN. In this case the RA changes. Therefore, the UE shall initiate a UMTS RA update procedure by establishing a RRC connection and initiating the... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.3.6.1 Intra SGSN Change | The difference compared with 3GPP R99 is, that an additional Update PDP Context in step 4) is needed. This message indicates to the xGGSN the reserved “not allocated” value for the traffic path as the Iu bearer is not yet allocated at the RAN. In step 12) the xGGSN tunnel endpoints are indicated to the RNC instead of t... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.3.6.2 Inter SGSN Change | The difference compared with 3GPP R99 is, that the Update PDP Context in step 8) indicates to the xGGSN the reserved “not allocated” value for the traffic path as the Iu bearer is not yet allocated at the RAN. In step 20) the xGGSN tunnel endpoints are indicated to the RNC instead of the SGSN tunnel endpoints. Furtherm... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.4 Session Management | The procedures are for packet bearer using a GGSN in the visited network with a 3G RAN, i.e. for the cSGSN / xGGSN architecture of the One Tunnel Approach. For all other bearer services or 2G RAN the R99 procedures and the SGSN / GGSN as specified in TS 23.060 apply. Modifications compared with 3GPP R99 are in italic. |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.4.1 PDP Context Activation Procedure | For better comparison with the 3GPP R99 PDP context activation procedure all PDP parameter checks and descriptions are included in the description, although the procedure applies only for bearer services using a GGSN in the visited network. The difference compared with 3GPP R99 is the creation of the PDP context on the... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.4.2 Secondary PDP Context Activation Procedure | The Secondary PDP Context Activation procedure may only be initiated after a PDP context is already activated for the same PDP address and APN. The procedure is illustrated in figure 41. The difference compared with 3GPP R99 is the creation of the PDP context on the xGGSN before the RAB setup. And this PDP context crea... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.4.3 Iu Release Procedure | The RAN initiates an Iu release procedure to release all RABs of an UE and the Iu connection. The Iu Release procedure is illustrated in figure 42. The difference compared with 3GPP R99 is the additional step 2) informing the xGGSN, that the transport tunnel endpoint at the RAN is no more allocated.
Figure 42: Iu Relea... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.4.4 Service Request Initiated by UE Procedure | The UE in PMM‑IDLE state sends the Service Request message to the cSGSN in order to establish the PS signalling connection for the upper layer signalling or for the resource reservation for active PDP context(s). This procedure is also used by an UE in PMM‑CONNECTED state to request the resource reservation for the act... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.4.5 Service Request Initiated by Network Procedure | When the xGGSN receives a downlink packet for a PDP context with a not allocated GTP tunnel (UE in PMM‑IDLE state), the xGGSN notifies the cSGSN. This initiates a paging request to trigger the Service Request procedure in the UE. Compared with 3GPP R99 the GTP tunnel at the xGGSN is not established after Iu release. Th... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.5 Charging | There are three different types of charging information which are collected by the SGSN and/or the GGSN: Mobility Management information, SMS information and PDP context information. In the One Tunnel Approach the cSGSN doesn’t collect the data volume for charging purposes. The charging functionality for Mobility Manag... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.6 CAMEL Considerations | In the One Tunnel Approach the data traffic passes only the xGGSN. Therefore volume dependent CAMEL functionality is performed by the xGGSN. All other CAMEL functionality remains in the cSGSN.
In the following, two aspects are described where the xGGSN is involved. The first one is the subscription change during establ... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.6.1 Subscription Change during Established PDP Context | If due to subscription change, the SCP needs to get control on PDP contexts that were established using the One Tunnel approach, then the cSGSN activates all required functionality when the subscription change is signalled by the HLR. If CAMEL prepaid applies the cSGSN sends an Update PDP Context to the xGGSN including... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.6.2 CAMEL Prepaid | In the One Tunnel Approach the data traffic passes only the xGGSN. Therefore volume dependent CAMEL prepaid is performed by the xGGSN. The cSGSN sends by means of the Create PDP Context Request message the prepaid budget for the required context to the xGGSN. Also during an inter cSGSN change the prepaid budget will be... |
997ad2510cb826711e63f644e1d2617f | 23.873 | 7.7 Lawful Interception | 3G TS 33.107 describes the architecture and functional requirements for interception for a 3rd generation mobile communication system. The specification applies to both SGSN and GGSN. There is only one difference interception at the GGSN is a national option which means in fact a GGSN is enabled for interception if an ... |
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