RAN Signaling Analysis Guide9 Inter-RAT Handover Procedure 9 About This Chapter Inter-RAT Handover Procedure The inter-RAT handover procedure is performed to hand over a UE from a WCDMA cell to a GSM cell or the other way round. This chapter describes inter-RAT handover in terms of types, protocols, triggering conditions, signaling procedure of a successful inter-RAT handover, signaling tracing on the RNC LMT, and elementary procedures. This chapter also describes the elementary procedures in terms of functions, triggering conditions, procedure, and signaling in abnormal conditions. 9.1 Types of Inter-RAT Handover Based on the direction of handover, inter-RAT handover is categorized into two types: interRAT handover from WCDMA to GSM and inter-RAT handover from GSM to WCDMA. 9.2 Inter-RAT CS Handover from WCDMA to GSM The procedure of inter-RAT CS handover from WCDMA to GSM is performed to hand over the CS services of a UE from the WCDMA system to the GSM system. 9.3 Inter-RAT CS Handover from GSM to WCDMA The procedure of inter-RAT CS handover from GSM to WCDMA is performed to hand over the CS services of a UE from the GSM system to the WCDMA system. 9.4 Inter-RAT PS Handover from WCDMA to GSM The procedure of inter-RAT PS handover from WCDMA to GSM is performed to hand over the PS services of a UE from the WCDMA system to the GSM system. 9.5 Inter-RAT PS Handover from GSM to WCDMA The procedure of inter-RAT PS handover from GSM to WCDMA is performed through cell reselection to WCDMA initiated by the UE. Issue 01 (2007-04-20) Huawei Technologies Proprietary 9-1 9 Inter-RAT Handover Procedure RAN Signaling Analysis Guide 9.1 Types of Inter-RAT Handover Based on the direction of handover, inter-RAT handover is categorized into two types: interRAT handover from WCDMA to GSM and inter-RAT handover from GSM to WCDMA. Based on services, the inter-RAT handover from WCDMA to GSM and that from GSM to WCDMA are further categorized into the following types: l l l l Inter-RAT CS handover from WCDMA to GSM Inter-RAT PS handover from WCDMA to GSM Inter-RAT CS handover from GSM to WCDMA Inter-RAT PS handover from GSM to WCDMA 9.2 Inter-RAT CS Handover from WCDMA to GSM The procedure of inter-RAT CS handover from WCDMA to GSM is performed to hand over the CS services of a UE from the WCDMA system to the GSM system. 9.2.1 Protocols Related to Inter-RAT CS Handover from WCDMA to GSM The procedure of inter-RAT CS handover from WCDMA to GSM complies with some 3GPP TS25 protocols. 9.2.2 Triggering Conditions of Inter-RAT CS Handover from WCDMA to GSM The signal quality of the WCDMA cell where the UE camps on is dissatisfactory or the load of the serving cell is heavy. 9.2.3 Signaling Procedure of Successful Inter-RAT CS Handover from WCDMA to GSM This part describes the signaling procedure of a successful inter-RAT CS handover from WCDMA to GSM. For the messages related to handover failures, refer to the elementary procedures. 9.2.4 Using the RNC LMT to Trace the Procedure of Inter-RAT CS Handover from WCDMA to GSM The signaling tracing function of the RNC LMT can be used to trace the signaling of an interRAT CS handover from WCDMA to GSM. 9.2.5 Elementary Procedures of Inter-RAT CS Handover from WCDMA to GSM This part describes the elementary procedures of inter-RAT CS handover from WCDMA to GSM in terms of triggering conditions and signaling procedures in normal and abnormal conditions. 9.2.1 Protocols Related to Inter-RAT CS Handover from WCDMA to GSM The procedure of inter-RAT CS handover from WCDMA to GSM complies with some 3GPP TS25 protocols. The compliance protocols are as follows: l l 3GPP TS25.331 "Radio Resource Control (RRC)" 3GPP TS25.413 "UTRAN Iu interface RANAP signalling" Huawei Technologies Proprietary Issue 01 (2007-04-20) 9-2 9. the UE will be handed over from the WCDMA cell to the GSM cell.2. The message contains the RAB ID. and the GSM information in bit strings. For the messages related to handover failures.2 Triggering Conditions of Inter-RAT CS Handover from WCDMA to GSM The signal quality of the WCDMA cell where the UE camps on is dissatisfactory or the load of the serving cell is heavy.3 Signaling Procedure of Successful Inter-RAT CS Handover from WCDMA to GSM This part describes the signaling procedure of a successful inter-RAT CS handover from WCDMA to GSM. refer to the elementary procedures. the activation time. Figure 9-1 Signaling procedure of a successful inter-RAT CS handover from WCDMA to GSM Note the following information about the procedure shown in Figure 9-1: l This figure presents only a brief of the signaling between the MSC server and the MSC (GSM) and that between the MSC (GSM) and the BSC (GSM). In such a condition.2.433 "UTRAN Iub interface Node B Application Part (NBAP) signalling" 9.RAN Signaling Analysis Guide l 9 Inter-RAT Handover Procedure 3GPP TS25. Huawei Technologies Proprietary 9-3 l Issue 01 (2007-04-20) . the GSM frequency. Figure 9-1 shows the signaling procedure of a successful inter-RAT CS handover from WCDMA to GSM. The SRNC sends a HANDOVER FROM UTRAN COMMAND message to the UE. if the signal quality of a neighboring GSM cell is satisfactory and its load is relatively light. 9-4 Huawei Technologies Proprietary Issue 01 (2007-04-20) . Context Table 9-1 lists the messages to be traced. Table 9-1 Messages to be traced Interfaces and Protocols to Be Traced Message Name on the LMT Message Name in Protocols Uu RRC_HO_FROM_UTRAN_C MD_GSM RRC_HO_FROM_UTRAN_F AIL NBAP_RL_DEL_REQ NBAP_RL_DEL_RSP RANAP_RELOCATION_RE QUIRED RANAP_RELOCATION_CO MMAND HANDOVER FROM UTRAN COMMAND HANDOVER FROM UTRAN FAILURE RADIO LINK DELETION REQUEST RADIO LINK DELETION RESPONSE RELOCATION REQUIRED RELOCATION COMMAND RELOCATION PREPARATION FAILURE IU RELEASE COMMAND IU RELEASE COMPLETE Iub Iu RANAP_RELOCATION_PR EPARATION_FAILURE RANAP_IU_RELEASE_CO MMAND RANAP_IU_RELEASE_CO MPLETE Procedure Step 1 Create a Uu tracing task by referring to Creating an RNC Tracing Task. Prerequisite l l The RNC LMT works properly.4 Using the RNC LMT to Trace the Procedure of Inter-RAT CS Handover from WCDMA to GSM The signaling tracing function of the RNC LMT can be used to trace the signaling of an interRAT CS handover from WCDMA to GSM. Figure 9-2 shows an example of Uu signaling tracing result.2. You have logged in to the RNC with an account authorized to perform tracing management.9 Inter-RAT Handover Procedure RAN Signaling Analysis Guide 9. Figure 9-3 Example of Iub signaling tracing result Step 3 Create an Iu tracing task by referring to Creating an RNC Tracing Task. Triggering Conditions The relocation preparation procedure can be triggered in either of the following conditions: l During an SRNS relocation.1 Relocation Preparation Procedure The relocation preparation procedure is performed to prepare resources for relocation of the SRNS.2.5 Elementary Procedures of Inter-RAT CS Handover from WCDMA to GSM This part describes the elementary procedures of inter-RAT CS handover from WCDMA to GSM in terms of triggering conditions and signaling procedures in normal and abnormal conditions. Figure 9-4 shows an example of Iu signaling tracing result. Figure 9-4 Example of Iu signaling tracing result ----End 9. the SRNC sends a RELOCATION REQUIRED message.2 Iu Release Procedure The Iu release procedure is performed for the CN to release an Iu connection and all the UMTS Terrestrial Radio Access Network (UTRAN) resources related only to that Iu connection. 9.3 Radio Link Deletion Procedure The radio link deletion procedure is performed to release resources in a NodeB for one or more established radio links towards a UE.2.5.5. Figure 9-3 shows an example of Iub signaling tracing result.2. 9. Relocation Preparation Procedure The relocation preparation procedure is performed to prepare resources for relocation of the SRNS.RAN Signaling Analysis Guide 9 Inter-RAT Handover Procedure Figure 9-2 Example of Uu signaling tracing result Step 2 Create an Iub tracing task by referring to Creating an RNC Tracing Task.2.5. 9. Huawei Technologies Proprietary 9-5 Issue 01 (2007-04-20) . If the resources partially or totally fail to be allocated. source SAC. If the target RNC or the target network system prepares the relevant resources successfully. source PLMN. The CN sends a response message to the SRNC. Triggering Conditions The Iu release procedure can be triggered in one of the following conditions: 9-6 Huawei Technologies Proprietary Issue 01 (2007-04-20) .9 Inter-RAT Handover Procedure l RAN Signaling Analysis Guide During an inter-RAT CS handover from WCDMA to GSM. the SRNC sends a RELOCATION REQUIRED message. which carries the information about the relevant resources allocated by the target RNC or the target network system. relocation cause. Procedure Figure 9-5 shows the relocation preparation procedure. The message contains the L3 information IE. target PLMN. such as the GSM system. the CN sends a RELOCATION COMMAND message when the preparation is complete. and target LAC. The SRNC sends a RELOCATION REQUIRED message to the CN. The CN interacts with the target RNC or the target network system. source LAC. Figure 9-5 Relocation preparation procedure The procedure shown in Figure 9-5 is described as follows: 1. l 2. The message contains certain information such as relocation type. l Iu Release Procedure The Iu release procedure is performed for the CN to release an Iu connection and all the UMTS Terrestrial Radio Access Network (UTRAN) resources related only to that Iu connection. the CN sends a RELOCATION PREPARATION FAILURE message. to prepare relevant resources. 3. the CN shall not send further RANAP connection-oriented messages on this particular connection. Triggering Conditions The CRNC sends a RADIO LINK DELETION REQUEST message. Figure 9-6 Iu release procedure The procedure shown in Figure 9-6 is described as follows: 1. Procedure Figure 9-7 shows the radio link deletion procedure. The CN sends an IU RELEASE COMMAND message to the SRNC to initiate the Iu release procedure. The SRNC releases the related UTRAN resources and then sends an IU RELEASE COMPLETE message to the CN. The Serving Radio Network Subsystem (SRNS) is relocated. Issue 01 (2007-04-20) Huawei Technologies Proprietary 9-7 . The SRNS relocation is canceled after a relocation resource allocation procedure is complete. Radio Link Deletion Procedure The radio link deletion procedure is performed to release resources in a NodeB for one or more established radio links towards a UE. 2. for example. The message indicates the cause for the release of the signaling connection. l l Procedure Figure 9-6 shows the Iu release procedure. NOTE After sending the IU RELEASE COMMAND message. The UTRAN requests the CN to release the resources on the Iu interface by. sending an IU RELEASE REQUEST message.RAN Signaling Analysis Guide l l 9 Inter-RAT Handover Procedure The transaction between the UE and the CN is complete. 9. 9.3 Signaling Procedure of Successful Inter-RAT CS Handover from GSM to WCDMA This part describes the signaling procedure of a successful inter-RAT CS handover from GSM to WCDMA.1 Protocols Related to Inter-RAT CS Handover from GSM to WCDMA The procedure of inter-RAT CS handover from GSM to WCDMA complies with some 3GPP TS25 protocols. 9.4 Using the RNC LMT to Trace the Procedure of Inter-RAT CS Handover from GSM to WCDMA The signaling tracing function of the RNC LMT can be used to trace the signaling of an interRAT CS handover from GSM to WCDMA. l 9. Upon reception of the message.5 Elementary Procedures of Inter-RAT CS Handover from GSM to WCDMA This part describes the elementary procedures of inter-RAT CS handover from GSM to WCDMA in terms of triggering conditions and signaling procedures in normal and abnormal conditions.3 Inter-RAT CS Handover from GSM to WCDMA The procedure of inter-RAT CS handover from GSM to WCDMA is performed to hand over the CS services of a UE from the GSM system to the WCDMA system. the NodeB shall delete the radio links specified by the message.2 Triggering Conditions of Inter-RAT CS Handover from GSM to WCDMA The signal quality of the GSM cell where the UE camps on is dissatisfactory or the load of the serving cell is heavy. 9.3. The Criticality Diagnostics field in the message indicates the failure cause. 9. 9-8 Huawei Technologies Proprietary Issue 01 (2007-04-20) . The CRNC sends a RADIO LINK DELETION REQUEST message to the NodeB. If any radio link fails to be deleted.3. l If all the radio links are deleted. the NodeB sends a RADIO LINK DELETION RESPONSE message. the NodeB sends a RADIO LINK DELETION RESPONSE message. refer to the elementary procedures. For the messages related to handover failures.9 Inter-RAT Handover Procedure RAN Signaling Analysis Guide Figure 9-7 Radio link deletion procedure The procedure shown in Figure 9-7 is described as follows: 1.3. 2.3.3. The NodeB sends a response message to the CRNC. Figure 9-8 shows the signaling procedure of a successful inter-RAT CS handover from GSM to WCDMA.331 "Radio Resource Control (RRC)" 3GPP TS25. 9.3 Signaling Procedure of Successful Inter-RAT CS Handover from GSM to WCDMA This part describes the signaling procedure of a successful inter-RAT CS handover from GSM to WCDMA. For the messages related to handover failures.1 Protocols Related to Inter-RAT CS Handover from GSM to WCDMA The procedure of inter-RAT CS handover from GSM to WCDMA complies with some 3GPP TS25 protocols.3.433 "UTRAN Iub interface Node B Application Part (NBAP) signalling" 9.413 "UTRAN Iu interface RANAP signalling" 3GPP TS25. The compliance protocols are as follows: l l l 3GPP TS25.3.RAN Signaling Analysis Guide 9 Inter-RAT Handover Procedure 9. refer to the elementary procedures.3. the UE will be handed over from the GSM cell to the WCDMA cell. In such a condition. if the signal quality of a neighboring WCDMA cell is satisfactory and its load is relatively light.2 Triggering Conditions of Inter-RAT CS Handover from GSM to WCDMA The signal quality of the GSM cell where the UE camps on is dissatisfactory or the load of the serving cell is heavy. Issue 01 (2007-04-20) Huawei Technologies Proprietary 9-9 . UE capability enquiry. the UE reports the failure to the GSM system.9 Inter-RAT Handover Procedure RAN Signaling Analysis Guide Figure 9-8 Signaling procedure of a successful inter-RAT CS handover from GSM to WCDMA Note the following information about the procedure shown in Figure 9-8: l This figure presents only a brief of the signaling between the MSC server and the MSC (GSM) and that between the MSC (GSM) and the BSC (GSM). and security mode control procedures. it sends a HANDOVER TO UTRAN COMPLETE message to the RNC. the RNC controls the UE to perform the UTRAN mobility information. The signaling messages traced may differ from the signaling messages shown in the figure in terms of the sequence. If the handover fails. Huawei Technologies Proprietary Issue 01 (2007-04-20) l l l l 9-10 . In addition. After receiving a HANDOVER TO UTRAN COMPLETE message. After receiving a RADIO LINK RESTORE INDICATION message. the RNC sends a RELOCATION DETECT message to the MSC server and informs the MSC server that the UE has been handed over from GSM to WCDMA. After the UE is handed over. the RNC sends a RELOCATION COMPLETE message to the MSC server. Prerequisite l l The RNC LMT works properly.3.RAN Signaling Analysis Guide 9 Inter-RAT Handover Procedure 9. Table 9-2 Messages to be traced Interfaces and Protocols to Be Traced Message Name on the LMT Message Name in Protocols RRC_HO_UTRAN_CMP RRC_UTRAN_MOBIL_INF O RRC_UTRAN_MOBIL_INF O_CONFIRM RRC_UTRAN_MOBIL_INF O_FAILURE RRC_UE_CAP_ENQUIRY Uu RRC_UE_CAP_INFO RRC_UE_CAP_INFO_CONF IRM RRC_SECURITY_MODE_C MD RRC_SECURITY_MODE_C MP RRC_SECURITY_MODE_F AIL NBAP_RL_SETUP_REQ Iub NBAP_RL_SETUP_RSP RNSAP_RL_SETUP_FAIL NBAP_RL_RESTORE_IND Issue 01 (2007-04-20) HANDOVER TO UTRAN COMPLETE UTRAN MOBILITY INFORMATION UTRAN MOBILITY INFORMATION CONFIRM UTRAN MOBILITY INFORMATION FAILURE UE CAPABILITY ENQUIRY UE CAPABILITY INFORMATION UE CAPABILITY INFORMATION CONFIRM SECURITY MODE COMMAND SECURITY MODE COMPLETE SECURITY MODE FAILURE RADIO LINK SETUP REQUEST RADIO LINK SETUP RESPONSE RADIO LINK SETUP FAILURE RADIO LINK RESTORE INDICATION 9-11 Huawei Technologies Proprietary . You have logged in to the RNC with an account authorized to perform tracing management. Context Table 9-2 lists the messages to be traced.4 Using the RNC LMT to Trace the Procedure of Inter-RAT CS Handover from GSM to WCDMA The signaling tracing function of the RNC LMT can be used to trace the signaling of an interRAT CS handover from GSM to WCDMA. Figure 9-9 Example of Uu signaling tracing result Step 2 Create an Iub tracing task by referring to Creating an RNC Tracing Task.9 Inter-RAT Handover Procedure RAN Signaling Analysis Guide Interfaces and Protocols to Be Traced Message Name on the LMT Message Name in Protocols RANAP_RELOCATION_RE Q RANAP_RELOCATION_RE Q_ACK Iu RANAP_RELOCATION_FAI LURE RANAP_RELOCATION_DE TECT RANAP_RELOCATION_CO MPLETE RELOCATION REQUEST RELOCATION REQUEST ACKNOWLEDGE RELOCATION FAILURE RELOCATION DECTECT RELOCATION COMPLETE Procedure Step 1 Create a Uu tracing task by referring to Creating an RNC Tracing Task. Figure 9-9 shows an example of Uu signaling tracing result. Figure 9-10 shows an example of Iub signaling tracing result. 9-12 Huawei Technologies Proprietary Issue 01 (2007-04-20) . Figure 9-10 Example of Iub signaling tracing result Step 3 Create an Iu tracing task by referring to Creating an RNC Tracing Task. Figure 9-11 shows an example of Iu signaling tracing result. 9.3.5. 9. Huawei Technologies Proprietary 9-13 Issue 01 (2007-04-20) .5 Elementary Procedures of Inter-RAT CS Handover from GSM to WCDMA This part describes the elementary procedures of inter-RAT CS handover from GSM to WCDMA in terms of triggering conditions and signaling procedures in normal and abnormal conditions.3.5. 9.3.5. Triggering Conditions The relocation resource allocation procedure can be triggered in either of the following conditions: l During an SRNS relocation.3.4 UE Capability Enquiry Procedure The UE capability enquiry procedure is performed to request a UE to transmit its capability information related to any radio access network so that the network can perform data configuration based on the UE capability.3.3. Relocation Resource Allocation Procedure The relocation resource allocation procedure is performed to allocate resources from the target RNS for an SRNS relocation.6 UTRAN Mobility Information Procedure The UTRAN mobility information procedure is performed for the network to allocate a new URNTI or Cell Radio Network Temporary Identifier (C-RNTI) to a UE or to inform the UE of mobility related information such as timer values and CN domain related information.5.1 Relocation Resource Allocation Procedure The relocation resource allocation procedure is performed to allocate resources from the target RNS for an SRNS relocation.3 Radio Link Restoration Procedure (Intra-RNC Handover or GSM to WCDMA CS Handover) The radio link restoration procedure (intra-RNC handover or GSM to WCDMA CS handover) is performed for a NodeB to notify the CRNC the establishment and re-establishment of uplink synchronization of one or more radio links. 9.5. the CN applies for resources from the target RNC.RAN Signaling Analysis Guide 9 Inter-RAT Handover Procedure Figure 9-11 Example of Iu signaling tracing result ----End 9. 9.5 Security Mode Control Procedure The security mode control procedure is performed to configure or reconfigure one or both of the ciphering and integrity protection algorithms for a UE.3. 9.5.2 Radio Link Setup Procedure (Intra-RNC Handover or GSM to WCDMA CS Handover) The radio link setup procedure (intra-RNC handover or GSM to WCDMA CS handover) is performed to set up a radio link in a NodeB controlled by the SRNC for a UE. The message contains certain information. the target RNC sends a RELOCATION FAILURE message. chosen encryption algorithm. If the resources partially or totally fail to be allocated or the target RNC rejects the SRNS relocation for some reason.9 Inter-RAT Handover Procedure l RAN Signaling Analysis Guide During an inter-RAT CS handover from GSM to WCDMA. and chosen integrity protection algorithm. The parameters include the UTRAN Radio Network Temporary Identifier (U-RNTI). 3. transport layer and physical layer information. the target RNC sends a RELOCATION REQUEST ACKNOWLEDGE message. Procedure Figure 9-12 shows the relocation resource allocation procedure. The CN sends a RELOCATION REQUEST message to the target RNC. the CN applies for resources from the target RNC. handover cause. 9-14 Huawei Technologies Proprietary Issue 01 (2007-04-20) . l Radio Link Setup Procedure (Intra-RNC Handover or GSM to WCDMA CS Handover) The radio link setup procedure (intra-RNC handover or GSM to WCDMA CS handover) is performed to set up a radio link in a NodeB controlled by the SRNC for a UE. If the resources are allocated. indicating the failure cause. The target RNC sends a response message to the CN. Figure 9-12 Relocation resource allocation procedure The procedure shown in Figure 9-12 is described as follows: 1. CN domain indicator. The target RNC allocates radio resources for the relocation. RAB. such as the IMSI of the UE. Iu signaling connection ID. and RAB parameters. encryption. target cell identifier. The message contains the radio resources and other parameters allocated to the UE. l 2. integrity protection. If the radio link fails to be set up. The message contains the failure cause in the Cause IE. Issue 01 (2007-04-20) Huawei Technologies Proprietary 9-15 . Procedure Figure 9-13 shows the radio link setup procedure (intra-RNC handover or GSM to WCDMA CS handover). If the radio link is set up. l 2. The CRNC sends a RADIO LINK SETUP REQUEST message to the NodeB.RAN Signaling Analysis Guide 9 Inter-RAT Handover Procedure Triggering Conditions The CRNC sends a RADIO LINK SETUP REQUEST message. Triggering Conditions The NodeB receives the UL signal from the UE. that is. l Radio Link Restoration Procedure (Intra-RNC Handover or GSM to WCDMA CS Handover) The radio link restoration procedure (intra-RNC handover or GSM to WCDMA CS handover) is performed for a NodeB to notify the CRNC the establishment and re-establishment of uplink synchronization of one or more radio links. the NodeB sends a RADIO LINK SETUP FAILURE message. The NodeB sends a response message to the CRNC. the NodeB finishes UL synchronization with the UE. Upon reception of the message. the NodeB saves the value of the Configuration Generation ID IE contained in the RADIO LINK SETUP REQUEST message and sends a RADIO LINK SETUP RESPONSE message. Figure 9-13 Radio link setup procedure (intra-RNC handover or GSM to WCDMA CS handover) The procedure shown in Figure 9-13 is described as follows: 1. the NodeB shall reserve the necessary resources and configure the new radio link according to the parameters given in the message. UE Capability Enquiry Procedure The UE capability enquiry procedure is performed to request a UE to transmit its capability information related to any radio access network so that the network can perform data configuration based on the UE capability. Figure 9-15 UE capability enquiry procedure 9-16 Huawei Technologies Proprietary Issue 01 (2007-04-20) . Triggering Conditions The UTRAN sends a UE CAPABILITY ENQUIRY message to acquire the UE capability information related to any radio access network. the NodeB sends a RADIO LINK RESTORE INDICATION message to the CRNC.9 Inter-RAT Handover Procedure RAN Signaling Analysis Guide Procedure Figure 9-14 shows the radio link restoration procedure (intra-RNC handover or GSM to WCDMA CS handover). Figure 9-14 Radio link restoration procedure (intra-RNC handover or GSM to WCDMA CS handover) After performing UL synchronization with the UE. Procedure Figure 9-15 shows the UE capability enquiry procedure. the UE sends a SECURITY MODE COMPLETE message to inform the SRNC of the completion. If the UE completes configuring or reconfiguring the relevant parameters for one or both of the ciphering and integrity protection algorithms. The SRNC reads the UE capability information and then sends a UE CAPABILITY INFORMA CONFIRM message to the UE through the downlink DCCH using AM or UM RLC. 3. The message contains the information about UE capabilities. Through a SECURITY MODE COMMAND message to the UE. The UE sends a UE CAPABILITY INFORMATION message to the SRNC through the uplink DCCH using AM or UM RLC.RAN Signaling Analysis Guide 9 Inter-RAT Handover Procedure The procedure shown in Figure 9-15 is described as follows: 1. l 2. 2. Security Mode Control Procedure The security mode control procedure is performed to configure or reconfigure one or both of the ciphering and integrity protection algorithms for a UE. Figure 9-16 Security mode control procedure The procedure shown in Figure 9-16 is described as follows: 1. If the SECURITY MODE COMMAND message contains neither Ciphering mode info IE nor Integrity protection mode info IE or if each of the two IEs has inconsistent Huawei Technologies Proprietary 9-17 l Issue 01 (2007-04-20) . the SRNC starts or reconfigures one or both of the ciphering and integrity protection configurations for the RBs or one CN domain and for all Signaling Radio Bearers (SRBs). Triggering Conditions The ciphering or integrity protection algorithm has changed. Procedure Figure 9-16 shows the security mode control procedure. The UE sends a response message to the SRNC. The SRNC sends a UE CAPABILITY ENQUIRY message to the UE through the downlink DCCH using AM RLC. l If the UE succeeds in conducting the operations specified by the UTRAN MOBILITY INFORMATION message.9 Inter-RAT Handover Procedure RAN Signaling Analysis Guide information. the UE sends a SECURITY MODE FAILURE message. If the UE fails to conduct the operations specified by the UTRAN MOBILITY INFORMATION message. Triggering Conditions The SRNC sends a UTRAN MOBILITY INFORMATION message to the UE. The UE sends a response message to the SRNC. the UE sends a UTRAN MOBILITY INFORMATION FAILURE message. indicating the failure of the security mode control procedure as well as the failure cause. 3. Procedure Figure 9-17 shows the UTRAN mobility information procedure. UTRAN Mobility Information Procedure The UTRAN mobility information procedure is performed for the network to allocate a new URNTI or Cell Radio Network Temporary Identifier (C-RNTI) to a UE or to inform the UE of mobility related information such as timer values and CN domain related information. The SRNC sends a UTRAN MOBILITY INFORMATION message to the UE. The UE starts to update the related fields according to the values of the IEs carried in the message. the UE sends a UTRAN MOBILITY INFORMATION CONFIRM message. Figure 9-17 UTRAN mobility information procedure The procedure shown in Figure 9-17 is described as follows: 1. l 9-18 Huawei Technologies Proprietary Issue 01 (2007-04-20) . 2. indicating the failure cause. 9.4.4.4 Inter-RAT PS Handover from WCDMA to GSM The procedure of inter-RAT PS handover from WCDMA to GSM is performed to hand over the PS services of a UE from the WCDMA system to the GSM system.433 "UTRAN Iub interface Node B Application Part (NBAP) signalling" 9. When the UE is in CELL_DCH state. refer to the elementary procedures.1 Protocols Related to Inter-RAT PS Handover from WCDMA to GSM The procedure of inter-RAT PS handover from WCDMA to GSM complies with some 3GPP TS25 protocols.4. Huawei Technologies Proprietary 9-19 l Issue 01 (2007-04-20) .4. 9. For the messages related to handover failures.413 "UTRAN Iu interface RANAP signalling" 3GPP TS25. 9. URA_PCH.4.2 Triggering Conditions of Inter-RAT PS Handover from WCDMA to GSM The signal quality of the WCDMA cell where the UE camps on is dissatisfactory or the load of the serving cell is heavy. it initiates cell reselection to perform a handover to GSM. 9.4.RAN Signaling Analysis Guide 9 Inter-RAT Handover Procedure 9.3 Signaling Procedure of Successful Inter-RAT PS Handover from WCDMA to GSM This part describes the signaling procedure of a successful inter-RAT PS handover from WCDMA to GSM. 9. l When the UE is in CELL_PCH.2 Triggering Conditions of Inter-RAT PS Handover from WCDMA to GSM The signal quality of the WCDMA cell where the UE camps on is dissatisfactory or the load of the serving cell is heavy. or CELL_FACH state. the UTRAN sends a CELL CHANGE ORDER message to the UE to perform a handover to GSM. 9.4.5 Elementary Procedures of Inter-RAT PS Handover from WCDMA to GSM This part describes the elementary procedures of inter-RAT PS handover from WCDMA to GSM in terms of triggering conditions and signaling procedures in normal and abnormal conditions. The compliance protocols are as follows: l l l 3GPP TS25.1 Protocols Related to Inter-RAT PS Handover from WCDMA to GSM The procedure of inter-RAT PS handover from WCDMA to GSM complies with some 3GPP TS25 protocols.4 Using the RNC LMT to Trace the Procedure of Inter-RAT PS Handover from WCDMA to GSM The signaling tracing function of the RNC LMT can be used to trace the signaling of an interRAT PS handover from WCDMA to GSM.331 "Radio Resource Control (RRC)" 3GPP TS25. refer to the elementary procedures. Based on the parameters in the system information. if the Packet Data Protocol (PDP) context does not need to be transferred. the SGSN directly sends an IU RELEASE COMMAND message to the SRNC. l l 9-20 Huawei Technologies Proprietary Issue 01 (2007-04-20) .4. or URA_FACH states. URA_PCH. The procedure of inter-RAT PS handover from WCDMA to GSM does not require such a message. the UE can initiate cell reselection to perform a handover to GSM. For the messages related to handover failures. the UE may be in CELL_PCH. The network does not initiate any cell reselection. because the UE shuts down transmission towards the WCDMA cell after cell reselection to a GSM cell.3 Signaling Procedure of Successful Inter-RAT PS Handover from WCDMA to GSM This part describes the signaling procedure of a successful inter-RAT PS handover from WCDMA to GSM.9 Inter-RAT Handover Procedure RAN Signaling Analysis Guide 9. Figure 9-18 shows the signaling procedure of a successful inter-RAT PS handover from WCDMA to GSM. Figure 9-18 Signaling procedure of a successful inter-RAT PS handover from WCDMA to GSM Note the following information about the procedure shown in Figure 9-18: l When there is a low PS data volume. The NodeB sends a RADIO LINK FAILURE INDICATION message. After the UE accesses a GSM cell. Issue 01 (2007-04-20) Huawei Technologies Proprietary 9-21 .RAN Signaling Analysis Guide 9 Inter-RAT Handover Procedure 9. Figure 9-19 shows an example of Uu signaling tracing result. Prerequisite l l The RNC LMT works properly. Table 9-3 Messages to be traced Interfaces and Protocols to Be Traced Message Name on the LMT Message Name in Protocols Uu RRC_CELL_CHANGE_ORD ER_FROM_UTRAN RRC_CELL_CHANGE_ORD ER_FROM_UTRAN_FAIL NBAP_RL_FAIL_IND CELL CHANGE ORDER FROM UTRAN CELL CHANGE ORDER FROM UTRAN FAILURE RADIO LINK FAILURE INDICATION RADIO LINK DELETION REQUEST RADIO LINK DELETION RESPONSE SRNS CONTEXT REQUEST SRNS CONTEXT RESPONSE SRNS DATA FORWARD COMMAND IU RELEASE COMMAND IU RELEASE COMPLETE Iub NBAP_RL_DEL_REQ NBAP_RL_DEL_RSP RANAP_SRNS_CONTEXT_ REQ RANAP_SRNS_CONTEXT_ RESP Iu RANAP_SRNS_DATA_FOR WARD_COMMAND RANAP_IU_RELEASE_CO MMAND RANAP_IU_RELEASE_CO MPLETE Procedure Step 1 Create a Uu tracing task by referring to Creating an RNC Tracing Task. Context Table 9-3 lists the messages to be traced.4 Using the RNC LMT to Trace the Procedure of Inter-RAT PS Handover from WCDMA to GSM The signaling tracing function of the RNC LMT can be used to trace the signaling of an interRAT PS handover from WCDMA to GSM. You have logged in to the RNC with an account authorized to perform tracing management.4. under the control of the network. 9. under the control of the network. a UE in CELL_DCH state to a GSM cell when the RABs established in the WCDMA system are only from the PS domain. Figure 9-21 Example of Iu signaling tracing result ----End 9.5.4. Figure 9-21 shows an example of Iu signaling tracing result. Figure 9-20 shows an example of Iub signaling tracing result.5 Elementary Procedures of Inter-RAT PS Handover from WCDMA to GSM This part describes the elementary procedures of inter-RAT PS handover from WCDMA to GSM in terms of triggering conditions and signaling procedures in normal and abnormal conditions. a UE in CELL_DCH state to a GSM cell when the RABs established in the WCDMA system are only from the PS domain.5.4 Radio Link Deletion Procedure The radio link deletion procedure is performed to release resources in a NodeB for one or more established radio links towards a UE.4.4. 9-22 Huawei Technologies Proprietary Issue 01 (2007-04-20) .5.4.5. 9. Figure 9-20 Example of Iub signaling tracing result Step 3 Create an Iu tracing task by referring to Creating an RNC Tracing Task.4.1 Cell Change Order from UTRAN Procedure The cell change order from UTRAN procedure is performed to hand over. 9.2 SRNS Context Transfer Procedure The SRNS context transfer procedure is performed to transfer SRNS contexts from the source RNC to the SGSN. 9. Cell Change Order from UTRAN Procedure The cell change order from UTRAN procedure is performed to hand over.9 Inter-RAT Handover Procedure RAN Signaling Analysis Guide Figure 9-19 Example of Uu signaling tracing result Step 2 Create an Iub tracing task by referring to Creating an RNC Tracing Task.3 Iu Release Procedure The Iu release procedure is performed for the CN to release an Iu connection and all the UMTS Terrestrial Radio Access Network (UTRAN) resources related only to that Iu connection. and NC mode. BCCH ARFCN. The IEs include BSIC. the UE starts timer T309 and initiates access to the GSM cell. If the UE accesses the GSM cell before the timer expires. the UE sends a CELL CHANGE ORDER FROM UTRAN FAILURE message to the SRNC. the 2G equipment needs to get the PDP contexts of the UE from the 3G equipment. The message contains certain IEs about the target cell. Procedure Figure 9-23 shows the SRNS context transfer procedure. l l 2. If the UE fails to access the GSM cell before the timer expires. Procedure Figure 9-22 shows the cell change order from UTRAN procedure. Figure 9-22 Cell change order from UTRAN procedure The procedure shown in Figure 9-22 is described as follows: 1. the SRNC orders the UE to perform a cell change to the GSM system. SRNS Context Transfer Procedure The SRNS context transfer procedure is performed to transfer SRNS contexts from the source RNC to the SGSN. the procedure ends. Through a CELL CHANGE ORDER FROM UTRAN message.RAN Signaling Analysis Guide 9 Inter-RAT Handover Procedure Triggering Conditions The network decides to hand over the UE to the GSM system. Issue 01 (2007-04-20) Huawei Technologies Proprietary 9-23 . Upon reception of the CELL CHANGE ORDER FROM UTRAN message. Band indicator. Triggering Conditions During the inter-RAT PS handover from WCDMA to GSM. The Serving Radio Network Subsystem (SRNS) is relocated. The SRNC sends an SRNS CONTEXT RESPONSE message to the SGSN. The UTRAN requests the CN to release the resources on the Iu interface by. The message includes the list of RABs whose contexts should be transferred. l l Procedure Figure 9-24 shows the Iu release procedure. Triggering Conditions The Iu release procedure can be triggered in one of the following conditions: l l The transaction between the UE and the CN is complete. The SRNS relocation is canceled after a relocation resource allocation procedure is complete. l If the transfer is successful. the SRNS CONTEXT RESPONSE message contains a Cause IE whose value is Invalid RAB ID. for example. If the SRNC fails to identify the ID of the RAB whose context should be transferred to the SGSN.9 Inter-RAT Handover Procedure RAN Signaling Analysis Guide Figure 9-23 SRNS context transfer procedure The procedure shown in Figure 9-23 is described as follows: 1. the message contains RAB IDs that include the sequence numbers for the downlink and uplink GTP PDUs and PDCP SDUs. l Iu Release Procedure The Iu release procedure is performed for the CN to release an Iu connection and all the UMTS Terrestrial Radio Access Network (UTRAN) resources related only to that Iu connection. The SGSN sends an SRNS CONTEXT REQUEST message to the SRNC. 9-24 Huawei Technologies Proprietary Issue 01 (2007-04-20) . 2. sending an IU RELEASE REQUEST message. The message indicates the cause for the release of the signaling connection. NOTE After sending the IU RELEASE COMMAND message. The SRNC releases the related UTRAN resources and then sends an IU RELEASE COMPLETE message to the CN.RAN Signaling Analysis Guide 9 Inter-RAT Handover Procedure Figure 9-24 Iu release procedure The procedure shown in Figure 9-24 is described as follows: 1. Triggering Conditions The CRNC sends a RADIO LINK DELETION REQUEST message. the CN shall not send further RANAP connection-oriented messages on this particular connection. The CN sends an IU RELEASE COMMAND message to the SRNC to initiate the Iu release procedure. Radio Link Deletion Procedure The radio link deletion procedure is performed to release resources in a NodeB for one or more established radio links towards a UE. 2. Issue 01 (2007-04-20) Huawei Technologies Proprietary 9-25 . Procedure Figure 9-25 shows the radio link deletion procedure. For details.5 Inter-RAT PS Handover from GSM to WCDMA The procedure of inter-RAT PS handover from GSM to WCDMA is performed through cell reselection to WCDMA initiated by the UE. Upon reception of the message. l 9.9 Inter-RAT Handover Procedure RAN Signaling Analysis Guide Figure 9-25 Radio link deletion procedure The procedure shown in Figure 9-25 is described as follows: 1. refer to 4 Location Update Procedure。 9-26 Huawei Technologies Proprietary Issue 01 (2007-04-20) . 2. If any radio link fails to be deleted. The Criticality Diagnostics field in the message indicates the failure cause. The NodeB sends a response message to the CRNC. The CRNC sends a RADIO LINK DELETION REQUEST message to the NodeB. the NodeB sends a RADIO LINK DELETION RESPONSE message. the NodeB shall delete the radio links specified by the message. l If all the radio links are deleted. the NodeB sends a RADIO LINK DELETION RESPONSE message.