01-06 Incoming Call Procedure

6 Incoming Call Procedure

About This Chapter

In the incoming call procedure, the network calls a UE and the UE responds to the paging. Thischapter describes incoming call setup and release in terms of protocols, triggering conditions,signaling procedure of a successful incoming call, signaling tracing on the RNC LMT, andelementary procedures. This chapter also describes the elementary procedures in terms offunctions, triggering conditions, procedure, and signaling in abnormal conditions.

6.1 Protocols Related to an Incoming CallThe incoming call procedure complies with some 3GPP TS25 protocols.

6.2 Triggering Conditions of an Incoming CallAn incoming call is received by a UE when a mobile phone or fixed-line phone calls the UE.

6.3 Signaling Procedure of a Successful Incoming CallThis part describes the signaling procedure of a successful incoming call. For the messagesrelated to incoming call failures, refer to the elementary procedures.

6.4 Using the RNC LMT to Trace the Incoming Call ProcedureThe signaling tracing function of the RNC LMT can be used to trace the signaling of an incomingcall.

6.5 Elementary Procedures of an Incoming CallThis part describes the elementary procedures of an incoming call in terms of triggeringconditions and signaling procedures in normal and abnormal conditions.

RANSignaling Analysis Guide 6 Incoming Call Procedure

Issue 01 (2007-04-20) Huawei Technologies Proprietary 6-1

6.1 Protocols Related to an Incoming CallThe incoming call procedure complies with some 3GPP TS25 protocols.

The compliance protocols are as follows:l 3GPP TS25.331 "Radio Resource Control (RRC)"

l 3GPP TS25.413 "UTRAN Iu interface RANAP signalling"

l 3GPP TS25.433 "UTRAN Iub interface Node B Application Part (NBAP) signalling"

6.2 Triggering Conditions of an Incoming CallAn incoming call is received by a UE when a mobile phone or fixed-line phone calls the UE.

A network pages a UE that camps on a cell.

6.3 Signaling Procedure of a Successful Incoming CallThis part describes the signaling procedure of a successful incoming call. For the messagesrelated to incoming call failures, refer to the elementary procedures.

Figure 6-1 shows the signaling procedure of a successful incoming call.

6 Incoming Call ProcedureRAN

Signaling Analysis Guide

6-2 Huawei Technologies Proprietary Issue 01 (2007-04-20)

Figure 6-1 Signaling procedure of a successful incoming call



Note the following information about the procedure shown in Figure 6-1:l An RRC connection can be set up on a DCH or CCH. This procedure takes setting up an

RRC connection on the DCH as an example.l If IP transport is applied to the Iub interface, the ALCAP procedure is not performed on

the Iub interface when radio links are set up, reconfigured, or deleted.

6.4 Using the RNC LMT to Trace the Incoming CallProcedure

The signaling tracing function of the RNC LMT can be used to trace the signaling of an incomingcall.

Prerequisitel The RNC LMT works properly.

l You have logged in to the RNC with an account authorized to perform tracing management.

Context

Table 6-1 lists the messages to be traced.

Table 6-1 Messages to be traced

InterfacesandProtocols toBe Traced

Message Name on the LMT Message Name in Protocols

Uu

RRC_PAGING_TYPE1 PAGING TYPE 1

RRC_PAGING_TYPE2 PAGING TYPE 2

RRC_RRC_CONNECT_REQ RRC CONNECTION REQUEST

RRC_RRC_CONN_SETUP RRC CONNECTION SETUP

RRC_RRC_CONN_REJ RRC CONNECTION REJECT

RRC_RRC_CONNECT_SETUP_CMP

RRC CONNECTION SETUPCOMPLETE

RRC_INIT_DIRECT_TRANSF INITIAL DIRECT TRANSFER

RRC_DL_DIRECT_TRANSF DOWNLINK DIRECT TRANSFER

RRC_UL_DIR_TRANSF UPLINK DIRECT TRANSFER

RRC_SECURITY_MODE_CMD SECURITY MODE COMMAND

RRC_SECURITY_MODE_CMP SECURITY MODE COMPLETE





RRC_SECURITY_MODE_FAIL SECURITY MODE FAILURE

RRC_RB_SETUP RADIO BEARER SETUP

RRC_RB_SETUP_CMP RADIO BEARER SETUP COMPLETE

RRC_RB_SETUP_FAIL RADIO BEARER SETUP FAILURE

RRC_RRC_CONN_REL RRC CONNECTION RELEASE

RRC_RRC_CONN_REL_CMP

RRC CONNECTION RELEASECOMPLETE

Iub

NBAP_RL_SETUP_REQ RADIO LINK SETUP REQUEST

NBAP_RL_SETUP_RSP RADIO LINK SETUP RESPONSE

NBAP_RL_SETUP_FAIL RADIO LINK SETUP FAILURE

NBAP_RL_RESTORE_IND RADIO LINK RESTORE INDICATION

NBAP_RL_RECFG_PREP RADIO LINK RECONFIGURATIONPREPARE

NBAP_RL_RECFG_REDAY RADIO LINK RECONFIGURATIONREADY

NBAP_RL_RECFG_FAIL RADIO LINK RECONFIGURATIONFAILURE

NBAP_RL_RECFG_COMMIT

RADIO LINK RECONFIGURATIONCOMMIT

NBAP_RL_RECFG_CANCEL

RADIO LINK RECONFIGURATIONCANCEL

NBAP_RL_DEL_REQ RADIO LINK DELETION REQUEST

NBAP_RL_DEL_RSP RADIO LINK DELETION RESPONSE

Iu

RANAP_PAGING PAGING

RANAP_INITIAL_UE_MESSAGE INITIAL UE MESSAGE

RANAP_COMMON_ID COMMON ID

RANAP_DIRECT_TRANSFER DIRECT TRANSFER

RANAP_SECURITY_MODE_COMMAND SECURITY MODE COMMAND






RANAP_SECURITY_MODE_COMPLETE SECURITY MODE COMPLETE

RANAP_SECURITY_MODE_REJ SECURITY MODE REJECT

RANAP_RAB_ASSIGNMENT_REQ RAB ASSIGNMENT REQUEST

RANAP_RAB_ASSIGNMENT_RESP RAB ASSIGNMENT RESPONSE

RANAP_IU_RELEASE_COMMAND IU RELEASE COMMAND

RANAP_IU_RELEASE_COMPLETE IU RELEASE COMPLETE

Procedure

Step 1 Create a Uu tracing task by referring to Creating an RNC Tracing Task.Figure 6-2 shows an example of Uu signaling tracing result.

Figure 6-2 Example of Uu signaling tracing result

As shown in Figure 6-2, multiple RRC_UL_DIR_TRANSF messages andRRC_DL_DIRECT_TRANSF messages are traced. That is because the UE and the RNCexchange signaling for several times during the incoming call procedure. TheRRC_UL_DIR_TRANSF messages have different contents, and so do theRRC_DL_DIRECT_TRANSF messages.



Step 2 Create an Iub tracing task by referring to Creating an RNC Tracing Task.Figure 6-3 shows an example of Iub signaling tracing result.

Figure 6-3 Example of Iub signaling tracing result

Step 3 Create an Iu tracing task by referring to Creating an RNC Tracing Task.Figure 6-4 shows an example of Iu signaling tracing result.

Figure 6-4 Example of Iu signaling tracing result

As shown in Figure 6-4, multiple RANAP_DIRECT_TRANSFER messages are traced. Thatis because the RNC and the CN exchange signaling for several times during the incoming callprocedure. The RANAP_DIRECT_TRANSFER messages have different contents.

----End

6.5 Elementary Procedures of an Incoming CallThis part describes the elementary procedures of an incoming call in terms of triggeringconditions and signaling procedures in normal and abnormal conditions.

6.5.1 Paging ProcedureThe paging procedure is performed when the CN calls a UE.

6.5.2 RRC Connection Setup Procedure




The RRC connection setup procedure is performed for the UE to set up a signaling connectionto the SRNC. RRC connection setup is always initiated by the UE. One UE has a maximum ofone RRC connection at a time.

6.5.3 Signaling Connection Setup Procedure (Incoming Call)The signaling connection setup procedure is performed to exchange NAS information betweenthe UE and the CN. The NAS information is related to authentication, service request, connectionsetup, and so on.

6.5.4 Authentication and Security Mode Control ProcedureThe authentication and security mode control procedure is performed for the UE and the networkto implement bi-directional authentication and to negotiate and configure the integrity protectionalgorithm and ciphering algorithm. This procedure ensures integrity and correctness of signaling.

6.5.5 Call Setup Procedure (Incoming Call)The call setup procedure is performed to set up a call.

6.5.6 RAB Setup ProcedureThe RAB setup procedure is performed to set up a user plane bearer.

6.5.7 Call Release Procedure (Incoming Call)The call release procedure is performed to release services and resources after a call ends.

6.5.8 RRC Connection Release ProcedureThe RRC connection release procedure is performed to release the signaling connection and allradio bearers between the UE and the UTRAN.

6.5.1 Paging ProcedureThe paging procedure is performed when the CN calls a UE.

Triggering Conditions

A terminal calls the UE.

Procedure

I. Paging a UE that Is in Idle Mode or in PCH State

Figure 6-5 shows the procedure for paging a UE that is in idle mode or in PCH state.

Figure 6-5 Paging procedure (for a UE that is in idle mode or in PCH state)

The procedure shown in Figure 6-5 is described as follows:

1. The CN sends a PAGING message to the SRNC.



2. The SRNC initiates the paging procedure by sending a PAGING TYPE 1 message to theUE through the Paging Control Channel (PCCH) on an appropriate occasion.

NOTE

The paging occasion is related to the International Mobile Subscriber Identity (IMSI) of the UE. TheUTRAN may page the same UE on several occasions to increase the probability of proper receptionof the paging message by the UE.

3. The UE in idle mode or in PCH state monitors the paging and receives the paging messagefrom the network layer.

The paging procedure ends.

II. Paging a UE that Is in CELL_DCH or CELL_FACH State

Figure 6-6 shows the procedure for paging a UE that is in CELL_DCH or CELL_FACH state.

Figure 6-6 Paging procedure (for a UE that is in CELL_DCH or CELL_FACH state)


1. The CN sends a PAGING message to the SRNC.2. The SRNC initiates the paging procedure by sending a PAGING TYPE 2 message to the

UE through the DCCH.3. The UE receives the PAGNG TPYE 2 message, reads it, and then reports to the NAS the

information such as the paging cause and the paging record type identifier.

The paging procedure ends.

6.5.2 RRC Connection Setup ProcedureThe RRC connection setup procedure is performed for the UE to set up a signaling connectionto the SRNC. RRC connection setup is always initiated by the UE. One UE has a maximum ofone RRC connection at a time.

Triggering ConditionsThe UE in idle mode shall initiate the RRC connection setup procedure when the NAS of theUE requests the establishment of a signaling connection.

ProcedureWhen the SRNC receives an RRC CONNECTION REQUEST message from the UE, the RadioResource Management (RRM) module of the RNC determines whether to accept or reject theRRC connection request according to a specific algorithm. If accepting the request, the RRMmodule determines whether to set up the RRC connection on a Dedicated Channel (DCH) or on




a Common Channel (CCH) according to a specific RRM algorithm. Typically, an RRCconnection is set up on the DCH.

I. RRC Connection Setup on a DCH

Figure 6-7 shows the procedure for setting up an RRC connection on a DCH.

Figure 6-7 RRC connection setup procedure (on a DCH)


1. The UE sends an RRC CONNECTION REQUEST message to the SRNC through theuplink Common Control Channel (CCCH), requesting the establishment of an RRCconnection.

2. Based on the cause in the RRC connection request and the system resource status, the SRNCdetermines to set up the RRC connection on a DCH and allocates the Radio NetworkTemporary Identity (RNTI), radio resources, and L1 and L2 resources.

3. The SRNC sends a RADIO LINK SETUP REQUEST message to the NodeB, requestingthe NodeB to allocate the specific radio link resources required for an RRC connection.

4. The NodeB responds with a RADIO LINK SETUP RESPONSE message to the SRNCafter successfully preparing the resources.

5. The SRNC uses the ALCAP protocol to set up the Iub user plane transport bearer andperforms the synchronization between the SRNC and the NodeB.

6. The SRNC sends an RRC CONNECTION SETUP message to the UE through the downlinkCCCH. The message contains the information about the DCH allocated by the SRNC.

7. The UE sends an RRC CONNECTION SETUP COMPLETE message to the SRNCthrough the uplink Dedicated Control Channel (DCCH) that is just set up.

The RRC connection setup procedure ends.

II. RRC Connection Setup on a CCH

Figure 6-8 shows the procedure for setting up an RRC connection on a CCH.



Figure 6-8 RRC connection setup procedure (on a CCH)


1. The UE sends an RRC CONNECTION REQUEST message to the SRNC through theuplink CCCH, requesting the establishment of an RRC connection.

2. Based on the cause in the RRC connection request and the system resource status, the SRNCdetermines to set up the RRC connection on a CCH.

3. The SRNC maps the logical channel of the UE onto a CCH in the cell.4. The SRNC sends an RRC CONNECTION SETUP message to the UE through the downlink

CCCH. The message contains the information about the CCH.5. The UE sends an RRC CONNECTION SETUP COMPLETE message to the SRNC

through the uplink CCCH.

The RRC connection setup procedure ends.

III. RRC Connection Rejected

Figure 6-9 shows the RRC connection rejected procedure.

Figure 6-9 RRC connection rejected procedure


1. The UE sends an RRC CONNECTION REQUEST message to the SRNC through theuplink CCCH, requesting the establishment of an RRC connection.

2. The SRNC determines to reject the RRC connection request according to a specificalgorithm and sends an RRC CONNECTION REJECT message to the UE. The messageindicates the reason for rejecting the RRC connection request.




6.5.3 Signaling Connection Setup Procedure (Incoming Call)The signaling connection setup procedure is performed to exchange NAS information betweenthe UE and the CN. The NAS information is related to authentication, service request, connectionsetup, and so on.

Triggering ConditionsThe UE sends a direct transfer message to initiate the signaling connection setup procedure.

ProcedureFigure 6-10 shows the signaling connection setup procedure.

Figure 6-10 Signaling connection setup procedure


1. The UE sends an INITIAL DIRECT TRANSFER message to the SRNC through the RRCconnection. The message contains the initial NAS information to be sent to the CN by theUE.

2. The SRNC receives the INITIAL DIRECT TRANSFER message from the UE and sendsan INITIAL UE MESSAGE to the CN through the Iu interface. The INITIAL UEMESSAGE contains the NAS information to be sent to the CN by the UE. The content ofthe NAS information is PAGING RESPONSE.

3. The CN sends a response message to the SRNC.l If accepting the request, the CN sends to the SRNC a CC message, indicating that the

SCCP connection is set up. After receiving the message, the SRNC confirms that thesignaling connection is set up.

l If rejecting the request, the CN sends to the SRNC a CJ message, indicating that theSCCP connection fails to be set up. After receiving the message, the SRNC confirmsthat the signaling connection fails to be set up and initiates the RRC release procedure.

6.5.4 Authentication and Security Mode Control ProcedureThe authentication and security mode control procedure is performed for the UE and the networkto implement bi-directional authentication and to negotiate and configure the integrity protectionalgorithm and ciphering algorithm. This procedure ensures integrity and correctness of signaling.




The UE and the CN exchange signaling. The network initiates the authentication and securitymode control procedure.

Procedure

Figure 6-11 shows the authentication and security mode control procedure.

Figure 6-11 Authentication and security mode control procedure


1. The CN sends to the SRNC a DIRECT TRANSFER message, indicatingAUTHENTICATION REQUEST.

2. The SRNC transparently sends the contents of the DIRECT TRANSFER message to theUE through a DOWNLINK DIRECT TRANSFER message.

3. The UE sends an UPLINK DIRECT TRANSFER message to the SRNC.

4. The SRNC transparently sends the contents of the UPLINK DIRECT TRANSFER messageto the CN through a DIRECT TRANSFER message, indicating AUTHENTICATIONRESPONSE. If the UMTS Subscriber Identity Module (USIM) regards that theauthentication succeeds, the UE returns a message with an XRES Information Element(IE).

5. The CN sends to the SRNC a SECURITY MODE COMMAND message to initiate thesecurity mode control procedure. The message contains the information about the supportedciphering and integrity protection algorithms.




6. The SRNC sends a SECURITY MODE COMMAND message to the UE to inform the UEof the integrity protection and ciphering algorithms that the UTRAN selects.

7. The UE sends a response message to the SRNC.l If the integrity protection and ciphering algorithms are configured successfully, the UE

sends a SECURITY MODE COMMAND COMPLETE message to the SRNC. TheSRNC then sends to the CN a SECURITY MODE COMMAND COMPLETE message,containing the information about the integrity protection and ciphering algorithms thatthe UE uses.

l If the UE does not support the integrity protection and ciphering algorithms, the UEsends to the SRNC a SECURITY MODE COMMAND FAILURE message thatcontains the error information and the reason for the failure. The SRNC then sends aSECURITY MODE COMMAND REJECT message to the CN.

6.5.5 Call Setup Procedure (Incoming Call)The call setup procedure is performed to set up a call.

Triggering ConditionsA UE receives a call from the CN.

ProcedureFigure 6-12 shows the call setup procedure.

Figure 6-12 Call setup procedure (incoming call)




1. The CN sends a DIRECT TRANSFER message to the SRNC. The message indicatesSETUP and contains the number of the caller and the bearing capability of the call.


3. The UE sends an UPLINK DIRECT TRANSFER message to the SRNC.4. The SRNC transparently sends the contents of the UPLINK DIRECT TRANSFER message

to the CN through a DIRECT TRANSFER message. The DIRECT TRANSFER messageindicates CALL CONFIRM and contains the information about the negotiated bearingcapability of the call.

5. An RAB is set up. For details, refer to 6.5.6 RAB Setup Procedure.6. The UE sends an UPLINK DIRECT TRANSFER message to the SRNC.7. The SRNC transparently sends the contents of the UPLINK DIRECT TRANSFER message

to the CN through a DIRECT TRANSFER message, indicating ALERTING to request thecalled terminal to ring.

8. The UE sends an UPLINK DIRECT TRANSFER message to the SRNC.9. The SRNC transparently sends the contents of the UPLINK DIRECT TRANSFER message

to the CN through a DIRECT TRANSFER message, indicating CONNECT. This meansthat the callee has answered the call.

10. The CN sends to the SRNC a DIRECT TRANSFER message, indicating CONNECTACKNOWLEDGE.


6.5.6 RAB Setup ProcedureThe RAB setup procedure is performed to set up a user plane bearer.

Triggering ConditionsA call is set up.

ProcedureI. Setting Up an RAB Successfully

Figure 6-13 shows the successful RAB setup procedure.




Figure 6-13 Successful RAB setup procedure


1. The CN sends an RAB ASSIGNMENT REQUEST message to the SRNC to initiate theRAB setup procedure.

2. The SRNC maps the Quality of Service (QoS) parameters for the RAB to the ATMAdaptation Layer type 2 (AAL2) link characteristic parameters and radio resourcecharacteristic parameters. The ALCAP on the Iu interface initiates a setup procedure foran Iu user plane transport bearer according to the AAL2 link characteristic parameters. (Forthe PS domain, this step does not exist.)

3. The SRNC sends to the NodeB a RADIO LINK RECONFIGURATION PREPAREmessage, requesting the NodeB to prepare for adding one or more DCHs to the existingradio links for carrying the RAB.

4. The NodeB allocates the appropriate resources and then sends a RADIO LINKRECONFIGURATION READY message to the SRNC.

5. The Iub ALCAP at the SRNC initiates a setup procedure for an Iub user plane transportbearer. The NodeB and the SRNC perform synchronization by exchanging uplink anddownlink synchronization frames in the DCH frame protocol.

6. The SRNC sends a RADIO BEARER SETUP message to the UE.

7. The SRNC sends a RADIO LINK RECONFIGURATION COMMIT message to theNodeB.

8. After performing radio bearer setup, the UE sends a RADIO BEARER SETUPCOMPLETE message to the SRNC.

9. The SRNC sends an RAB ASSIGNMENT RESPONSE message to the CN.

The RAB is set up.

II. Failing to Set Up an RAB

Figure 6-14 shows the unsuccessful RAB setup procedure.



Figure 6-14 Unsuccessful RAB setup procedure


1. The CN sends an RAB ASSIGNMENT REQUEST message to the SRNC to initiate theRAB setup procedure.

2. The SRNC sends to the CN an RAB ASSIGNMENT RESPONSE message, indicating theID of the RAB that fails to be set up and the reason for the failure.

6.5.7 Call Release Procedure (Incoming Call)The call release procedure is performed to release services and resources after a call ends.

Triggering ConditionsA call ends and the caller hangs up.

ProcedureFigure 6-15 shows the call release procedure.




Figure 6-15 Call release procedure (incoming call)


1. The CN sends to the SRNC a DRIECT TRANSFER message, indicating DISCONNECT.This informs the UE that the caller has hanged up.

2. The SRNC transparently sends the contents of the DRIECT TRANSFER message to theUE through a DOWNLINK DIRECT TRANSFER message.

3. The UE sends an UPLINK DRIECT TRANSFER message to the SRNC.4. The SRNC transparently sends the contents of the UPLINK DRIECT TRANSFER message

to the CN through a DIRECT TRANSFER message. The DIRECT TRANSFER messageindicates RELEASE which requests release of the call.

5. The CN sends to the SRNC a DRIECT TRANSFER message, indicating RELEASECOMPLETE.

6. The SRNC transparently sends the contents of the DRIECT TRANSFER message to theUE through a DOWNLINK DIRECT TRANSFER message.

7. The CN sends an IU RELEASE COMMANDE message to the SRNC to request call releaseon the Iu interface. The message indicates the reason for the Iu release.

8. The ALCAP protocol on the Iu interface initiates an Iu data transport bearer releaseprocedure.

9. The SRNC sends an IU RELEASE COMPLETE message to the CN.

6.5.8 RRC Connection Release ProcedureThe RRC connection release procedure is performed to release the signaling connection and allradio bearers between the UE and the UTRAN.




After an RAB is released, the SRNC judges whether the RRC connection carries any other RABof the UE. If judging that the RRC connection does not carry any other RAB of the UE, theSRNC initiates an RRC connection release procedure.

Procedure

According to the resource occupied by the RRC connection, there are two types of RRCconnection release procedure: release of an RRC connection from a DCH and release of an RRCconnection from a CCH.

NOTE

If an RRC connection needs to be released after an outgoing call succeeds, the RRC connection on theDCH is released. If a radio bearer fails to be set up, the RRC connection on the CCH is released.

I. Releasing an RRC Connection from a DCH

Figure 6-16 shows the procedure for releasing an RRC connection from a DCH.

Figure 6-16 RRC connection release procedure (from a DCH)


1. The SRNC sends an RRC CONNECTION RELEASE message to the UE through theDCCH.

NOTE

The SRNC may send the RRC CONNECTION RELEASE message several times to increase theprobability of proper reception of the message by the UE. The RRC SNs of these messages are thesame. The number of retransmissions and the transmission intervals are determined by the SRNC. Ifthe SRNC does not receive an RRC CONNECTION RELEASE COMPLETE message from the UEafter sending the RRC CONNECTION RELEASE message for four times, the SRNC regards thatthe UE has released the RRC connection.

2. The UE sends an RRC CONNECTION RELEASE COMPLETE message to the SRNC.




3. The SRNC sends to the NodeB a RADIO LINK DELETION REQUEST message,requesting the NodeB to delete the radio link resources in the NodeB.

4. After releasing the resources, the NodeB sends a RADIO LINK DELETION RESPONSEmessage to the SRNC.

5. The SRNC uses the ALCAP protocol to initiate an Iub user plane transport bearer releaseprocedure.

The RRC connection release procedure ends.

II. Releasing an RRC Connection from a CCH

Figure 6-17 shows the procedure for releasing an RRC connection from a CCH.

Figure 6-17 RRC connection release procedure (from a CCH)


1. The SRNC sends an RRC CONNECTION RELEASE message to the UE through theCCCH.

2. The UE sends an RRC CONNECTION RELEASE COMPLETE message to the SRNC.



01-06 Incoming Call Procedure

Documents

Transcript of 01-06 Incoming Call Procedure