USOO8428O35B2
(12) United States Patent (10) Patent No.: US 8,428,035 B2 Nishida et al. (45) Date of Patent: Apr. 23, 2013
(54) MOBILE COMMUNICATION METHOD, (56) References Cited RADIO ACCESS NETWORKAPPARATUS AND MOBILE STATION U.S. PATENT DOCUMENTS 8,306,537 B2 * 1 1/2012 Burbidge et al...... 455,436 (75) Inventors: Katsutoshi Nishida, Tokyo (JP); 2010/01 13010 A1* 5/2010 Tenny et al...... 455,423 Shimpei Kawakatsu, Yokohama (JP); 2010, 0182971 A1* 7, 2010 Chin ...... 370,329 2010/0202413 A1* 8/2010 Vikberg et al. ... 370,332 Kenichi Katayama, Fujisawa (JP); 2010/0279648 A1* 1 1/2010 Song et al...... 455,404.1 Kenichiro Aoyagi, Yokosuka (JP) 2010, O297979 A1* 11, 2010 Watfa et al...... 455,404.1 2011/00696.18 A1* 3/2011 Wong et al...... 370,244 (73) Assignee: NTT DoCoMo, Inc., Tokyo (JP) 2011/0216645 A1* 9/2011 Song et al...... 370,216 2012,0002545 A1 1/2012 Watfa et al...... 370,235 (*) Notice: Subject to any disclaimer, the term of this 2012/0064884 A1 3/2012 Ramachandran et al. . 455,422.1 patent is extended or adjusted under 35 FOREIGN PATENT DOCUMENTS U.S.C. 154(b) by 0 days. WO 2008.156402 A1 12/2008 WO 2009/081268 A1 T 2009 (21) Appl. No.: 13/578,054 OTHER PUBLICATIONS International Search Report w/translation from PCT/JP2011/052774 (22) PCT Fled: Feb. 9, 2011 dated Apr. 19, 2011 (2 pages). 3GPP TS 23.272V9.2.0; “3rd Generation Partnership Project; Tech nical Specification Group Services and System Aspects; Circuit (86) PCT NO.: PCT/UP2011/052774 Switched Fallback in Evolved Packet System; Stage 2 (Release 9); Dec. 2009 (64 pages). S371 (c)(1), Office Action w/English translation mailed on Apr. 19, 2011 in cor (2), (4) Date: Oct. 25, 2012 responding Japanese Application No. 2010-027047 (4 pages). Office Action w/English translation mailed on Apr. 19, 2011 in cor (87) PCT Pub. No.: WO2O11AO99529 responding Japanese Application No. 2010-291 160, which is a Divi sional Application of Priority Claimed Application No. JP2010 PCT Pub. Date: Aug. 18, 2011 027047 (5 pages). (65) Prior Publication Data * cited by examiner US 2013/OO393O1 A1 Feb. 14, 2013 Primary Examiner — Frank Duong (74) Attorney, Agent, or Firm — Osha Liang LLP (30) Foreign Application Priority Data (57) ABSTRACT Feb. 9, 2010 (JP) ...... P2O1O-O27047 A mobile communication method according to the present invention includes the steps of transmitting an "Extended Service Request' from a mobile station UE in Idle mode to a (51) Int. C. mobility management node MME via a radio base station H04B 7/26 (2006.01) eNodeB; transmitting an “Initial UE Context Setup Request' from the mobile station UE to the radio base station eNodeB, (52) U.S. C. the “Initial UE Context Setup Request containing priority call USPC ...... 370/335 information; and preferentially allocating resources to the E-RAB for the mobile station UE by the radio base station (58) Field of Classification Search ...... 370/310, eNodeB based on the priority call information contained in 370/328 350, 401; 455/436 444 the received “Initial UE Context Setup Request.” See application file for complete search history. 4 Claims, 14 Drawing Sheets
U.S. Patent Apr. 23, 2013 Sheet 1 of 14 US 8.428,035 B2
FIG. 1
U.S. Patent Apr. 23, 2013 Sheet 2 of 14 US 8,428,035 B2
FIG. 2
S1001 EPC
MSCVLR P-GW SGSN PRIORITY UE ORIGINATING CALL Extended Service Request S1003 (CSFallback Indicator) S1002, ExtendedCSFaitaciali?t Service Request PRIORITY CONTROLIN ERAB SETUP PROCESSING Initial UE Context Setup Request (CSFallback indicator) S1004 (PRIORITY CALL INFORMATION) PERFORY FRORTYCONTROLPROCESSINGAeNE-S1005 SETUPE-RAB S1008 initial UE Context Setup Response S S1006 5a.GTPW2 RSEModi S1010 BearerGTPModi Response S1AP Handover Required N- S1009 SA Cause Target RNC identifier.Source to Target ransparent Gontainer(PRIORITY CALL INFORMAT N) PRIORITY CONTROLINRABSETUP PROCESSING | S1011 Forward Relocation Request S10 12 Source to TargetTransparent Container PRIORITY CALL INFORMATION), S1013 f RIORITY CALL INFORMATION) Relocation Request (Source to SS Transparent Container PERFORM (PRIORITY CALL INFORMATION), PRIORITY CONTROL C PREFERENTIALLY ACQUIRE RESOURCES PRIORITY CALL INFORMATION) PROCESSING ATRNC Relocation--m---H---...-- Request Acknowledge - m a arms ax m (INFORMATIONELEMENT ADDRESSED TO eNodeB (PRIORITY CAL INFORMATON) Forward Relocation Response
S1017 (INFORMATIONELEMENT ADDRESSED TO SAP Handover Command eNodeB (PRIORITY CALL INFORMATION) ', SES ELEMENT ADDRESSED HOfrom E-UTRAN TO eNodeB(PRIORITY CALL INFORMATION) Command (CSFallback indicator, PRIORITYO CALL NoryTO) Handover to UTRAN Complete S1020 (PRIORITY CALL INFORMATION) ( ) Relocation Complete S1018 S1019 - Forward Relocation Complete S1021 Forward Relocation Complete Acknowledge Modify Bearer Request S1023 as asse erase asset asse soa5 S1024
U.S. Patent Apr. 23, 2013 Sheet 5 of 14 US 8,428,035 B2
FIG. 5
RECEIVE Relocation Request S301
S302 RESOURCES NOT-AVAILABLE AREAVAILABLE S304
AVAILABLE DETERMINE NON-PRIORITY PRIORITY PRIORITY
ALLOCATE ACQUIRE Negative RESOURCES RESOURCES Response
S303 S306 S305 U.S. Patent Apr. 23, 2013 Sheet 6 of 14 US 8,428,035 B2
FIG. 6
RECEIVE Relocation Request S401
S402 NON-PRIORITY DETERMINE PRIORITY
PRIORITY
S403
ALOCATE RESOURCES (FRESOURCES ARE SHORT, ALLOCATE RESOURCES
ACOURE RESOURCES (IFRESOURCES ARE SHORT,
BY DISCONNECTING SEND Negative Response) COMMUNICATION WITH OTHER NON-PRIORITYUE) U.S. Patent Apr. 23, 2013 Sheet 7 of 14 US 8,428,035 B2
FIG. 7
HOfrom EffRECEIVE Nicommand h S50
S502
DETERMINE RESTRICTION OF RESTRICTED ACCESS TO UTRAN NOT-RESTRICTED S503 DETERMINE NON-PRIORITY PRIORITY
S505 PRIORITY S504 SEND Handover to PERFORME-UTRAN UTRAN Complete RE-CONNECTION PROCESSING WITHOUT SENDING Handover to UTRAN Complete U.S. Patent Apr. 23, 2013 Sheet 8 of 14 US 8,428,035 B2
FIG. 8 S2001 RNC MSCWLRS2002 S2003 AM invite PRIORITY UETERMINATING CAL L PRIORITY CALL INFORMATION (TTCITU-T, ETC) S2004 NY) DETERMINE WHETHERSGs status ISSGs-ASSOCIATED S2006 Ó TRANSMTPaging TOMMN WITHWHICH SGSAP-PAGING-REQUEST SGS-ASSOCATIONSESTABLISHED S2007 Paci TMsiris) (TRANSMTPaging BEFOREIAM NCASE OF PrePaging) aging Locationinformation
CNDominglyPRIORITYC PRIORITY CAL S-TMSI(or IMSI) CNDOmainindicator:CS PRIORITY CALL INFORMATION RRCConnection Request PRIORITY al NFORMATION S2008 RRCCopection Setup S2009 RRCConnection Complete(Extended Service Request) (SSECSFallback XSETUP indicator SR RRC S20 2 S2010 sh Extendedtrig. Segie Request S1 Service Request TPRIORITY CONTROLINERABSEIUPPROCESSING Initial UE Context Setup Request -S2014 UE Capabilities (CSFallback Indicator) t S2015 EYCINEMAPERFORMPRIORITY CONTROL PROCESSING AT eNodeB TS) initial UE Context Setup Response S2018 SETUPS2O1 6III" "a PROCESSINGX GTPW2 Modify Bearer Request Y S2017 - GTPW2 Modify Bearer Recuest PRIORITYS1AP:Handoyer CONTROLINRABSETUP Required PROCESSING S2019- -S2021|| - - -w- (S1AP Cause,Spurce to Target Transparent Continer PRIORITY CALL INFORMATION) Forward Relocation Request (Source to Target Transparent Container PRIORITY CALL INFORMATION) S2020 S2022 -y Relocation Request () (Source to TargetTransparent Container(PRIORITY CALL INFORMATION) S2O23 Relocation Request Acknowledge S2024 YPREFERENTALY ACQEE RESOURCES O orward Relocation Response
S1AP:Handover Command E-UTRANCAA S2026 S2025
Q Handover to UTRAN Complete S2O3 S2O32 P Relocation Comn S2028 S2029 Forward Relocation Complete Forward Relocation Complete Acknowledge R Modify BeareRequest ease asse erase S2033 ast Sigers Se U.S. Patent Apr. 23, 2013 Sheet 9 of 14 US 8,428,035 B2
FIG. 9
S3001 S3002 s PRIORITYUE AM Invite TERMINATING CAL PRIORITY CALL INFORMATION (TTC/ITU-T, ETC) S3003 ODETERMINE WHETHER SGS status SSGS-ASSOCATED S3005 S3004 - (TRANSMIT Paging TOMMN WITH
WHECH SGS-ASSOCATIONS
SGSAP-PAGING-REQUEST (TRANSMTPagingESTABLISHED BEFORE
CS Service Notification TMSI(or IMS) IAM N CASE OF PrePaging) Locationlinformation (TMS) PRIORITY CALL INFORMATION S3008 S3009 S S Service Request Extended Service Extended Service R Request (CSFallback indicator) (CSFallback indicator) UE Context Modification Request (CSFallback Indicator) S3010 PRIORITY CALL INFORMATION
S3011 O DETECT REQUEST FORCSFB
S303
U.S. Patent Apr. 23, 2013 Sheet 12 of 14 US 8,428,035 B2 FIG. 12
MVSISIN EPC MSCIVR MME S-GW SGSN PRIORITY UE ORIGINATING CALL ServiceExtended Request (CSFallback Indicator) Extended Service Request (CSFallback indicator) E-RABwww.s SETUP ormmrm www.x PROCESSING a -w- --- Initial UE Context Setup Request r (CSFallback indicator) J ERRORSHORTAGE MAYOCCURDUETO OF RESOURCES A NECESSARY FORE-RAB SETUP SETUPE-RAB Initial UE Context Setup Response GTPv2 Modify Bearer Requést
GTP2 Modify Bearer Response S1AP Handover Required (S1AP Cause, Target RNCIdentifier,Source to Target Transparent Container) RABSETUP PROCESSING Forward Relocation Request. (Source to TargetTransparent pontaine) Relocation Request towoccur (Source to Target Transparent Container) ERROR MAY OCCURDUETO SHORTAGE OF RESOURCES L NECESSARY FORRAB SETUP Relocation Reduest Acknowledge a- r
S1AP Handover Command - FireRese HO from E-UTRAN Command (CSFallback indicator) Handover to UTRAN Complete ERROR MAY OCCURDUETO RRC CONGESTION NUTRAN Relocation Complete Forward Relocation Complete Forward Relocation Complete Acknowledge Modify Bearer Request Modify Bearer Response
ast ae arset U.S. Patent Apr. 23, 2013 Sheet 13 of 14 US 8,428,035 B2
FIG. 13
MSCWLR AM/Invite PRIORITY UETERMINATING CALL PRIORITY CALL INFORMATION (TTCITU-T, ETC) O DETERMINE WHETHER SGS status SSGS-ASSOCATED OTRANSMIT 23 TQMMN.WITHWHICH SGSAP-PAGINGREQUEST ifiRSilsifREENiASEOFPePaging)SGS-ASSOCATION IS ESTABLISHED Paging TMSI(or IMSI) Locationinformation CNDomaligatePRIORITY CALL SPRIORITY CANFORMATION Paging NFORMATION S-TMSI(or IMSI) CN Domainindicator.CS RRC Connection Request ERROR MAY OCCURDUE TO RRCConnection Setup RRC CONGESTONINE-UTRAN RRCConnection Complete(Extended Service Request) CS Fallback indicator S-TMSXSETUP ON RRC Extended Service Request CSFallback indicator S-TMSXSETUP ONS-AP Service Request ERABSETUPPROCESSING Initial UE Context Setup Request UE Capabilities
CS Fallback indicator ODETECT REQUEST FORCSFB is ERROR MAYOCCURDUE TO SHORTAGE OF SETUPE-RAB RESOURCESNECESSARY FORE-RABSETUP - - initial UE Context Setup Response GTPv2 Modify Bearer Request PROCESSINGA GTPV2 Modify Bearer Request RABSETUP PROCESSING S1AP:Handover Required (S1AP Cause,Source to Targe Transparent Container) Forward Relocation Request C (Source to TargetTransparent Container) r Relocation Request SHORTAGERROR MAYOCCURDUETO OF RESOURCES (Source to TargetTransparent Container) NECESSARY FOR RABSETUP Relocation Request Acknowledge Forward Relocation Response
S1AP:Handover Command - m HO fro E-UTRAN Comman Handover to UTRAN Com ERROR MAYOCCURDUETO RRC CONGESTION NUTRAN
Relocation Complete Forward Relocation Complete Forward Relocation Complete Acknowledge N Modify BeareRequest Modify Bearer Response -St -St. Writt st at asses U.S. Patent Apr. 23, 2013 Sheet 14 of 14 US 8,428,035 B2
FIG. 14
SNILMMS MSCNR PRIORITY UE AMInvite TERMINATING CALL
PRIORITY CALL INFORMATION (TTCITU-T, ETC) ODETERMINE WHETHER SGS status SSGS-ASSOCATED OTRANSMIT Paging TOMMN WITH WHICH SGS-ASSOCATIONS ESTABLISHED (TRANSMIT Paging BEFORE SGSAP-PAGING-REQUEST (AMN CASE OF PrePaging) CS Service Notification TMSI(or IMSI) (TMS) PRIORITY CARINFORMATIONLocationinformation Service Request RSS Service ES Service CSFallback indicator CS Fallback indicator Context Modification Request CSFallback indicator
ODETECT REQUEST FORCSFB
ERRORRESOURCES MAYOCCURDUETO NECESSARY FORRAB SHORTAGE SETUP OF UE Context Modification Response
UE Context Release Command PERFORMPROCESSINGA
US 8,428,035 B2 1. 2 MOBILE COMMUNICATION METHOD, Moreover, the CSFB procedure has another problem that RADIO ACCESS NETWORKAPPARATUS an E-RAB to serve as a packet bearer for the prioritized AND MOBILE STATION mobile station UE cannot be set up in E-RAB setup process ing if resources necessary for E-RAB setup are short, as TECHNICAL FIELD shown in a part B in FIG. 13. Further, the CSFB procedure has still another problem that The present invention relates to a mobile communication a RAB to serve as a packet bearer for the prioritized mobile method, a radio access network apparatus and a mobile sta station UE cannot be set up in RAB setup processing if tion. resources necessary for RAB setup are short, as shown in a 10 part C in FIG. 13. BACKGROUND ART Furthermore, the CSFB procedure has yet another problem that the radio network controller RNC cannot establish RRC For mobile communication systems of LTE (Long Term connection for transmission of a handovercontrol signal from Evolution) standard, “CS Fallback (CSFB)procedures”have the prioritized mobile station UE if the RRC function on the 15 UTRAN side is congested, as shown in a part D in FIG. 13. been specified in order for a mobile station UE in Idle mode Thirdly, FIG. 14 shows part of operations of a CSFB pro on E-UTRAN (Evolved Universal Terrestrial Radio Access cedure involved in terminating call processing for a priori Network) not supporting circuit-switched type of communi tized mobile station UE in Active mode in the foregoing cations to perform circuit-switched type of communications. mobile communication system. In this CSFB procedure, the E-RAB for the prioritized mobile station UE is already setup. SUMMARY OF THE INVENTION In this CSFB procedure, if the radio base station eNodeB detects shortage of resources necessary for RAB setup on Problems to be Solved by the Invention UTRAN on the occasion of receiving a “Context Modifica According to the above CSFB procedure, it is necessary to tion Request' including a "CSFB Indicator, the radio base set up an "E-RAB (Evolved Radio Access Bearer) that is a 25 station eNodeB cannot preferentially perform control pro radio bearer on E-UTRAN first, and thereafter to set up a cessing necessary for handover for the Subsequent packet “RAB (Radio Access Bearer) that is a radio bearer on communications as shown in a part A in FIG. 14. UTRAN (Universal Terrestrial Radio Access Network) or Hence, the present invention has been made in consider GERAN (GSM EDGE Radio Access Network). ation of the foregoing problems, and has an objective to The CSFB procedure, however, has a problem of being 30 provide a mobile communication method, a radio access net unable to preferentially allocate resources to the setup pro work apparatus and a mobile station which, in a CSFB pro cessing of the E-RAB as a packet bearer and the setup pro cedure for communications to be prioritized such as an origi cessing of the RAB as a packet bearer. nating call or terminating call of a prioritized mobile station, Likewise, the CSFB procedure has another problem of enable preferential setup of E-RAB and RAB as packet bear being unable to preferentially establish RRC (Radio 35 ers and priority control for a RRC signal in the CSFB proce Resource Control) connection for transmission of a signal to dure. request a start of circuit-switched type of communications Means for Solving the Problems from a prioritized mobile station UE. A first feature of the present invention is a mobile commu With reference to FIGS. 12 to 14, these problems will be nication method including the steps of transmitting a start described in detail. 40 request signal for circuit-switched type of communications Firstly, FIG. 12 shows part of operations of a CSFB pro from a mobile station in Idle mode to a mobility management cedure involved in originating call processing for a prioritized node via a radio access network apparatus of a first commu mobile station UE in the foregoing mobile communication nication system that does not support circuit-switched type of system. communications; transmitting a radio bearer setup request The CSFB procedure has a problem that an E-RAB to serve 45 signal from the mobility management node to the radio access as a packet bearer for the prioritized mobile station UE cannot network apparatus of the first communication system, the be set up in E-RAB setup processing if resources necessary radio bearer setup request signal containing priority call for E-RAB setup are short, as shown in a part A in FIG. 12. information and requesting setup of a radio bearer of the first In addition, the CSFB procedure has another problem that communication system between the mobile station and the a RAB to serve as a packet bearer for the prioritized mobile 50 radio access network apparatus of the first communication station UE cannot be set up in RAB setup processing if system; and preferentially allocating resources to a radio resources necessary for RAB setup are short, as shown in a bearer of the first communication system, by the radio access part B in FIG. 12. network apparatus of the first communication system based Moreover, the CSFB procedure has still another problem on the received priority call information. that a radio network controller RNC cannot establish RRC 55 A second feature of the present invention is Summarized as connection for transmission of a handovercontrol signal from including the steps of transmitting a start request signal for the prioritized mobile station UE if the RRC function on the circuit-switched type of communications from mobile station UTRAN side is congested, as shown in a part C in FIG. 12. to a mobility management node via a radio access network Secondary, FIG. 13 shows part of operations of a CSFB apparatus of a first communication system that does not Sup procedure involved in terminating call processing for a pri 60 port, circuit-switched type of communications, the mobile oritized mobile station UE in Idle mode in the foregoing station having a radio bearer of the first communication sys mobile communication system. tem already set up between the mobile station and the radio The CSFB procedure has a problem that a radio base sta access network of the first communication system; transmit tion eNodeB cannot establish RRC connection for transmis ting a setting modification request signal containing priority sion of a handover control signal from the prioritized mobile 65 call information from the mobility management node to the Station UE if the RRC function on the E-UTRAN side is radio access network apparatus of the first communication congested, as shown in a part A in FIG. 13. system; determining, by the radio access network apparatus US 8,428,035 B2 3 4 of the first communication system, whether or not there are communication system even though an access to a second available resources on a second communication system that communication system that Supports circuit-switched type of Supports circuit-switched type of communications, in communications is restricted, transmit a response signal to response to the received setting modification request signal; the handover request signal to a radio access network appa and performing a procedure of releasing the radio bearer of 5 ratus of the second communication system. the first communication system in the case where the priority Effects of the Invention call information is contained in the setting modification AS has been described above, according to the present request signal even through it is determined that there are no invention, it is possible to provide a mobile communication available resources on the second communication system. method, a radio access network apparatus and a mobile sta A third feature of the present invention is a radio access 10 network apparatus of a first communication system that does tion which, in a CSFB procedure for communications to be not support circuit-switched type of communications, the prioritized such as an originating call or terminating call of a radio access network apparatus Summarized as being config prioritized mobile station, enable preferential setup of ured to: send a mobility management node a start request E-RAB and RAB as packet bearers and priority control for a signal for circuit-switched type of communications received 15 RRC signal in the CSFB procedure. from a mobile station in Idle mode; receive a radio bearer setup request signal from the mobility management node, the BRIEF DESCRIPTION OF DRAWINGS radio bearer setup request containing priority call information and requesting setup of a radio bearer of the first communi FIG. 1 is an overall configuration diagram of a mobile cation system between the mobile station and the radio access communication system according to a first embodiment of the network apparatus of the first communication system; and present invention. preferentially allocate resources to the radio bearer of the first FIG. 2 is a sequence diagram showing operations of the communication system based on the priority call information mobile communication system according to the first embodi contained in the received radio bearer setup request signal. ment of the present invention. A fourth feature of the present invention is a radio access 25 FIG. 3 is a flowchart showing an operation of a radio base network apparatus of a first communication system that does station eNodeB in the mobile communication system accord not support circuit-switched type of communications, the ing to the first embodiment of the present invention. radio access network apparatus Summarized as being config FIG. 4 is a flowchart showing an operation of the radio base ured to: send a mobility management node a start request station eNodeB in the mobile communication system accord signal for circuit-switched type of communications received 30 ing to the first embodiment of the present invention. from a mobile station having a radio bearer of the first com FIG. 5 is a flowchart showing an operation of a radio munication system between the mobile station and the radio network controller RNC according to the first embodiment of access network apparatus of the first communication system; the present invention. determine whether or not there are available resources on a FIG. 6 is a flowchart showing an operation of the radio second communication system that Supports circuit-switched 35 network controller RNC according to the first embodiment of type of communications in response to a setting modification the present invention. request signal received from the mobility management node: FIG. 7 is a flowchart showing an operation of a mobile and perform a radio bearer release procedure of the first station UE according to the first embodiment of the present communication system if priority call information is con invention. tained in the setting modification request signal even though 40 FIG. 8 is a sequence diagram showing operations of the it is determined that there are not available resources on the mobile communication system according to the first embodi second communication system. ment of the present invention. A fifth feature of the present invention is a radio access FIG. 9 is a sequence diagram showing operations of the network apparatus of a second communication system that mobile communication system according to the first embodi Supports circuit-switched type of communications, the radio 45 ment of the present invention. access networkapparatus Summarized as being configured to: FIG. 10 is a flowchart showing an operation of the radio after a radio bearer of a first communication system that does base station eNodeB in the mobile communication system not support circuit-switched type of communications is set up according to the first embodiment of the present invention. between a mobile station and a radio access network appara FIG. 11 is a flowchart showing an operation of the radio tus of the first communication system, receive a handover 50 base station eNodeB in the mobile communication system request signal containing priority call information from the according to the first embodiment of the present invention. radio access network apparatus of the first communication FIG. 12 is a diagram for explaining problems of a conven system via the mobility management node and a packet tional mobile communication system. Switch of the second communication system; and preferen FIG. 13 is a diagram for explaining problems of the con tially allocate resources to a radio bearer of the second com 55 ventional mobile communication system. munication system between the mobile station and the radio FIG. 14 is a diagram for explaining a problem of the con access network apparatus of the second communication sys ventional mobile communication system. tem based on the priority call information contained in the received handover request signal. MODES FOR CARRYING OUT THE INVENTION A sixth feature of the present invention is a mobile station 60 Summarized as being configured to transmit a start request (Mobile Communication System according to First Embodi signal for circuit-switched type of communications to a ment of the Present Invention) mobility management node via a radio access network appa In reference to FIGS. 1 to 11, description will be provided ratus of a first communication system that does not support for a mobile communication system according to a first circuit-switched type of communications; and if priority call 65 embodiment of the present invention. The mobile communi information is contained in a handover request signal cation system according to this embodiment includes both received from the radio access network apparatus of the first E-UTRAN and UTRAN. US 8,428,035 B2 5 6 Specifically, as shown in FIG. 1, the mobile communica allocates the resources to the E-RAB for the prioritized tion system according to this embodiment includes a gateway mobile station UE in the case where the resources necessary device P-GW (PDN Gateway), a serving gateway device for E-RAB setup are acquired, in step S107. S-GW (Serving Gateway), a mobility management node On the other hand, when determining that such resources MME (Mobility Management Entity), a radio base station are not available, the radio base station eNodeB aborts the eNodeB, a circuit switching device MSC (Mobile-service CSFB procedure (PS HO procedure) and transitions to a Switching Center), a packet switch SGSN (Serving GPRS “Release with Redirection procedure” in step S108. Support Node), a radio network controller RNC, and a radio For example, in the “Release with Redirection procedure.” base station NodeB (not illustrated). the radio base station eNodeB may send the mobility man In the first place, in reference to FIG. 2, description will be 10 agement node MME an “Initial UE Context Setup Response' provided for part of operations of a CSFB procedure involved containing error information indicating the transition to the in originating call processing of a prioritized mobile station “Release with Redirection procedure.” UE in the mobile communication system according to this In the above procedure, the processing in step S106 may be embodiment. omitted. In this case, when determining that the priority call As shown in FIG. 2, when a prioritized mobile station UE 15 information is contained in step S104, the radio base station in Idle mode on E-UTRAN detects execution of an originat eNodeB may preferentially reserve resources for the E-RAB ing call operation for starting circuit-switched type of com for the prioritized mobile station UE, and may allocate the munications in step S1001, the prioritized mobile station UE resources to the E-RAB for the prioritized mobile station UE transmits an “Extended Service Request containing a in the case where the resources necessary for E-RAB setup “CSFB Indicator' to the radio base station eNodeB in step are acquired, in step S107. S10O2. Secondly, a second example of the priority control process In step 1003, the radio base station eNodeB transmits the ing for the “Initial UE Context Setup Request' is explained in “Extended Service Request containing the “CSFB Indica reference to FIG. 4. tor” to the mobility management node MME. As shown in FIG. 4, when the radio base station eNodeB In step S1004, if the mobility management node MME 25 receives an “Initial UE Context Setup Request' in step S201, determines that the CSFB procedure should be prioritized by the radio base station eNodeB determines whether or not the referring to “connection cause information (for example, priority call information is contained in the “Initial UE Con cause priority connection) or “connection type information text Setup Request' in step S202. (for example, an originating call for emergency call)” which When determining that the priority call information is not is contained in the signal received in step S1003, “subscriber 30 contained, the radio base station eNodeB performs usual pro profile information held by the mobility management node cessing of allocating resources to an E-RAB in step S203. MME (for example, a priority user).” or the like, the mobility Here, if the radio base station eNodeB cannot allocate the management node MME transmits an “Initial UE Context resources to the E-RAB, the radio base station eNodeB trans Setup Request containing the “CSFB Indicator' and priority mits a “Negative Response' indicating that effect to the call information to the radio base station eNodeB. 35 mobility management node MME. In step S1005, the radio base station eNodeB performs On the other hand, when determining that the priority call priority control processing for the received “Initial UE Con information is contained, the radio base station eNodeB text Setup Request.” determines whether or not resources necessary for RAB setup Here, the priority control processing for the “Initial UE on a relocation target RAT, i.e., on UTRAN are available in Context Setup Request' is explained in reference to FIGS. 3 40 step S204. and 4. When determining that such resources are available, the Firstly, a first example of the priority control processing is radio base station eNodeB preferentially allocates resources explained in reference to FIG. 3. to the E-RAB for the prioritized mobile station UE in step As shown in FIG. 3, when the radio base station eNodeB S2O5. receives an “Initial UE Context Setup Request' in step S101, 45 Here, when the resources necessary for E-RAB setup on the radio base station eNodeB determines whether or not E-UTRAN are not available, the radio base station eNodeB resources necessary for E-RAB setup are available in step releases the resources allocated to a non-prioritized mobile S102. station UE and preferentially allocates the resources to the When determining that such resources are available, the E-RAB for the prioritized mobile station UE. radio base station eNodeB performs usual processing of allo 50 On the other hand, when such resources are not available, cating resources to an E-RAB in step S103. the radio base stationeNodeBaborts the CSFB procedure (PS On the other hand, when determining that such resources HO procedure) and transitions to the “Release with Redirec are not available, the radio base station eNodeB determines tion procedure' in step S206. whether or not the priority call information is contained in the For example, in the “Release with Redirection procedure.” “Initial UE Context Setup Request” in step S104. 55 the radio base station eNodeB may send the mobility man When determining that the priority call information is not agement node MME an “Initial UE Context Setup Response' contained, the radio base station eNodeB sends the mobility containing error information indicating the transition to the management node MME a “Negative Response' indicating “Release with Redirection procedure.” that the resource allocation is not possible in step S105. Here, the processing in step S204 may be performed at a On the other hand, when determining that the priority call 60 time point Ain FIG. 4. In this case, when determining that the information is contained, the radio base station eNodeB aforementioned resources are available in step S204, the determines whether or not resources necessary for RAB setup radio base station eNodeB may perform usual processing of on a relocation target RAT (Radio Access Technology), i.e., allocating the resources to the E-RAB. In contrast, when on UTRAN are available in step S106. determining that the aforementioned resources are not avail When determining that such resources are available, the 65 able in step S204, the radio base station eNodeB may abort radio base station eNodeB preferentially reserves resources the CSFB procedure (PSHO procedure) and transition to the for the E-RAB for the prioritized mobile station UE and “Release with Redirection procedure' in step S206. US 8,428,035 B2 7 8 In this case, when determining the priority call information On the other hand, when determining that such resources is contained instep S202, the radio base station eNodeB may are not available, the radio network controller RNC deter preferentially allocate the resources to the E-RAB for the mines whether or not the priority call information is con prioritized mobile station UE in step S205. tained in the “Relocation Request' in step S304. Here, when resources necessary for E-RAB setup on When determining that the priority call information is con E-UTRAN are not available, the radio base station eNodeB tained, the radio network controller RNC allocates the may release the resources allocated to a non-prioritized resources to the RAB for the prioritized mobile station UE, if mobile station UE and preferentially allocate the resources to the resources necessary for RAB setup are acquired from the the E-RAB for the prioritized mobile station UE. resources reserved in advance for the RAB for the prioritized Returning to FIG. 2, after the E-RAB is set up between the 10 radio base station eNodeB and the prioritized mobile station mobile station UE, in step S306. UE in step S1006, the radio base station eNodeB transmits an On the other hand, when determining that the priority call “Initial UE Context Setup Response' to the mobility man information is not contained, the radio network controller agement node MME in step S1007. RNC transmits a “Negative Response' indicating that effect The mobility management node MME transmits a “GTPv2 15 to the packet switch SGSN in step S305. Modify Bearer Request' to the serving gateway device S-GW Secondly, a second example of the priority control process in step S1008 and the serving gateway device S-GW transmits ing for a “Relocation Request' is explained in reference to a “GTPv2 Modify Bearer Response' to the mobility manage FIG. 6. ment node MME in step S1009. As shown in FIG. 6, when the radio network controller In step S1010, the radio base station eNodeB sends the RNC receives a “Relocation Request' in step S401, the radio mobility management node MME a “Handover Required network controller RNC determines whether or not the prior containing “Cause.” “Target RNC Identifier. “Source eNo ity call information is contained in the “Relocation Request' deB Identifier. “Source to Target Transparent Container.” in step S402. and the like. When determining that the priority call information is con Here, the “Source to Target Transparent Container con 25 tained, the radio network controller RNC preferentially allo tains the aforementioned priority call information. cates resources to the E-RAB for the prioritized mobile sta In step S1011, the mobility management node MME sends tion UE in step S403. the packet switch SGSN a “Forward Relocation Request' In this step, if the resources necessary for RAB setup on containing the “Source to Target Transparent Container.” UTRAN are not available, the radio network controller RNC Here, the mobility management node MME generates the 30 “Forward Relocation Request' containing the whole “Source releases the resources allocated to a non-prioritized mobile to Target Transparent Container” in the received “Handover station UE and allocates the resources to the RAB for the Required and transmits the “Forward Relocation Request' prioritized mobile station UE. to the packet switch SGSN. On the other hand, when determining that the priority call Instead, the mobility management node MME may detect 35 information is not contained, the radio network controller that the call is to be prioritized in a method like the one RNC performs usual processing of allocating resources to the described in step S1004, generate the “Forward Relocation RAB in step S404. Request' containing the priority call information and the like, In this step, when the resources cannot be allocated to the and transmit the “Forward Relocation Request' to the packet RAB, the radio network controller RNC transmits a “Nega Switch SGSN. 40 tive Response' indicating that effect to the packet switch In step S1012, the packet switch SGSN transmits a “Relo SGSN. cation Request containing the "Source to Target Transparent Returning to FIG. 2, after the radio network controller Container” to the radio network controller RNC. RNC successfully allocates the resources to the RAB for the In this step, the packet switch SGSN generates the “Relo prioritized mobile station UE, the radio network controller cation Request containing the whole “Source to Target 45 RNC sends the packet switch SGSN a “Relocation Request Transparent Container in the received “Forward Relocation Acknowledge” in which the priority call information is con Request' and transmits the “Relocation Request' to the radio tained in an information element addressed to the radio base network controller RNC. station eNodeB in step S1014. Alternatively, the packet switch SGSN may detect the pri In step S1015, the packet switch SGSN sends the mobility ority call information contained in received “Forward Relo 50 management node MME a “Forward Relocation Response' cation Request generate the "Relocation Request contain in which the priority call information is contained in an infor ing the priority call information and the like and transmit the mation element addressed to the radio base station eNodeB. “Relocation Request' to the radio network controller RNC. In step S1016, the mobility management node MME sends In step S1013, the radio network controller RNC performs the radio base station eNodeB a “Handover Command” in the priority control processing for a “Relocation Request' 55 which the priority call information is contained in an infor thus received. mation element addressed to the radio base station eNodeB. Here, the priority control processing for a “Relocation In step S1017, the radio base station eNodeB sends the Request' is explained in reference to FIGS. 5 and 6. prioritized mobile station UE a “HO from E-UTRAN Com Firstly, a first example of the priority control processing for mand containing the “CSFB Indicator' and the priority call a “Relocation Request' is explained by referring to FIG. 5. 60 information. As shown in FIG. 5, when the radio network controller In step S1018, the prioritized mobile station UE performs RNC receives a “Relocation Request' in step S301, the radio priority control processing for a "HO from E-UTRAN Com network controller RNC determines whether or not resources mand thus received. Here, the priority control processing for necessary for RAB setup are available in step S302. a “HO from E-UTRAN Command” is explained in reference When determining that such resources are available, the 65 to FIG. 7. radio network controller RNC performs usual processing of As shown in FIG. 7, when a mobile station UE (for allocating the resources to the RAB in step S303. example, a prioritized mobile station UE) receives a “HO US 8,428,035 B2 10 from E-UTRAN Command” in step S501, the mobile station deB transmits the “Paging containing the priority call infor UE determines whether or not an access to UTRAN is mation to the mobile station UE in step S2007. restricted in step S502. In step S2008, the mobile station UE transmits a “RRC Here, the mobile station UE may determine whether or not Connection Request containing the priority call information the access to UTRAN is restricted based on an information to the radio base station eNodeB based on the received “Pag element in the “HO from E-UTRAN Command” or may ing. determine whether or not the access to UTRAN is restricted In step S2009, the radio base station eNodeB performs based on broadcast information in a cell under the control of priority control processing for the received “RRCConnection the radio network controller RNC. Request.” When determining that the access is restricted, the mobile 10 For example, the radio base station eNodeB may be con station UE determines whether or not the priority call infor figured to accept only the “RRC Connection Request con mation is contained in the "HO from E-UTRAN Command” taining the priority call information when the RRC function in step S503. or the like on the E-UTRAN side is congested. When determining that the priority call information is not Incidentally, the radio base station eNodeB may transmit a contained, the mobile station UE determines that the CSFB 15 "Paging not containing the priority call information to the procedure cannot be performed, and performs processing of mobile station UE in step S2007. In this case, the radio base re-connecting to E-UTRAN without transmitting a “Han station eNodeB does not perform the priority control process dover to UTRAN Complete' to the radio network controller ing for the received “RRC Connection Request' in step RNC in step S504. S2O09. On the other hand, when determining that the priority call When accepting the received “RRC Connection Request.” information is contained, the mobile station UE transmits a the radio base station eNodeB transmits a “RRC Connection “Handover to UTRAN Complete' to the radio network con Setup' to the mobile station UE in step S2010. troller RNC in step S505 (corresponding to S1019 shown in In step S2011, the mobile station UE sends the radio base FIG. 2). station eNodeB a “RRC Connection Complete' in which a Meanwhile, when determining that the access is not 25 “CSFB Indicator is contained in an “Extended Service restricted in step S502, the mobile station UE transmits the Request.” “Handover to UTRAN Complete' to the radio network con The radio base station eNodeB transmits the "Extended troller RNC in step S505 (corresponding to S1019 shown in Service Request containing the “CSFB Indicator' to the FIG. 2). mobility management node MME in step S2012, and the Incidentally, the processing in step S1018 may be omitted. 30 mobility management node MME transmits the “Service In step S1020, the radio network controller RNC performs Request' to the circuit switching device MSC in step S2013. priority control processing for the “Handover to UTRAN The following operations in steps S2014 to S2035 are the Complete' thus received. same as the operations in steps S1004 to S1025 shown in FIG. For example, the radio network controller RNC may be 2. configured to accept only the “Handover to UTRAN Com 35 In the third place, in reference to FIG.9, description will be plete' containing the priority call information when the RRC provided for part of operations in a CSFB procedure involved function or the like on the UTRAN side is congested. in terminating call processing for a prioritized mobile station When accepting the received “Handover to UTRAN Com UE in Active mode in the mobile communication system plete, the radio network controller RNC transmits a “Relo according to this embodiment. In this CSFB procedure, the cation Complete' to the packet switch SGSN in step S1021. 40 E-RAB for the prioritized mobile station UE is already setup. The packet switch SGSN transmits a “Forward Relocation The operations in steps S3001 to S3005 are the same as the Complete' to the mobility management node MME in step operations in steps step S2001 to S2005 shown in FIG.8. S1022, and the mobility management node MME transmits a The mobility management node MME transmits a “CS “Forward Relocation Complete Acknowledge' to the packet Service Notification” to the mobile station UE in step S3006, switch SGSN in step S1023. 45 and transmits a “Service Request' to the circuit switching The packet switch SGSN transmits a “Modify Bearer device MSC in step S3007. Request' to the serving gateway device S-GW in step S1024 The mobile station UE transmits an "Extended Service and the serving gateway device S-GW transmits a “Modify Request' containing a “CSFB Indicator' to the radio base Bearer Response' to the packet switch SGSN in step S1025. station eNodeB in step S3008, and the radio base station In the second place, in reference to FIG. 8, description will 50 eNodeB transmits the “Extended Service Request contain be provided for part of operations of a CSFB procedure ing the “CSFB Indicator' to the mobility management node involved in terminating call processing for a prioritized MME in step S3009. mobile station UE in Idle mode in the mobile communication In step S3009, the mobility management node MME system according to this embodiment. receives the “Extended Service Request that is a response As shown in FIG. 8, when a terminating call to a mobile 55 signal to step S3006. Upon this reception, the mobility man station UE in Idle mode on E-UTRAN is made from a priori agement node MME transmits a “UE Context Modification tized mobile station in step S2001, the circuit switching Request' containing the “CSFB Indicator” and the priority device MSC receives an "IAM/Invite' containing the priority call information to the radio base station eNodeB in step call information in step S2002, checks that “SGs status” is S301O. “SGs-ASSOCIATED in step S2003, and transmits a 60 When the radio base station eNodeB detects that the “SGSAP-PAGING-REQUEST (Paging)” containing the pri “CSFB Indicator is contained in the received “UE Context ority call information to the mobility management node Modification Request' in step S3011, the radio base station MME with which SGs association is established in steps eNodeB performs priority control processing for the received S2004 and S2005. “UE Context Modification Request” in step S3012. The mobility management node MME transmits a “Pag 65 Here, the priority control processing for a “UE Context ing containing the priority call information to the radio base Modification Request' is explained in reference to FIGS. 10 station eNodeB in step 2006, and the radio base station eNo and 11. US 8,428,035 B2 11 12 Firstly, a first example of the priority control processing for containing error information indicating the transition to the a “UE Context Modification Request' is described in refer “Release with Redirection procedure.” ence to FIG. 10. Here, the processing in step S704 may be performed at a As shown in FIG. 10, when the radio base station eNodeB time point B in FIG. 11. In this case, the radio base station receives a “UE Context Modification Request' in step S601, eNodeB may continue the CSFB procedure (PSHO proce the radio base station eNodeB determines whether or not dure) in step S703 when determining that the above resources resources necessary for RAB setup on a relocation target are available in step S704, and may abort the CSFB procedure RAT, i.e., on UTRAN are available in step S602. (PSHO procedure) and transition to the “Release with Redi When determining that such resources are available, the rection procedure' in step S706 when determining that the radio base station eNodeB continues the CSFB procedure in 10 step S603. Specifically, in step S3013 shown in FIG. 9, the above resources are not available in step S704. radio base station eNodeB transmits a “UE Context Modifi In this case, when determining that the priority call infor cation Response' to the mobility management node MME. mation is contained in step S702, the radio base station eNo On the other hand, when determining that such resources deB may continue the CSFB procedure (PSHO procedure) in are not available, the radio base station eNodeB determines 15 step S705. whether or not the priority call information is contained in the Returning to FIG. 9, the processing X shown in FIG. 8 is “UE Context Modification Request” in step S604. implemented thereafter. When determining that the priority call information is con The mobile communication system according to this tained, the radio base station eNodeB aborts the CSFB pro embodiment can preferentially perform the E-RAB setup cedure (PSHO procedure) and transitions to the “Release processing, the RAB setup processing, and the RRC connec with Redirection procedure” in step S605. tion establishment processing in the CSFB procedure for In the “Release with Redirection procedure, for example, communications to be prioritized such as an originating call the radio base station eNodeB may send the mobility man ora terminating call from a prioritized mobile station UE, and agement node MME a “UE Context Modification Response' thereby can preferentially perform the CSFB procedure containing error information indicating the transition to the 25 involved in the originating call processing or the terminating “Release with Redirection procedure.” call processing for the prioritized mobile station UE. On the other hand, when determining that the priority call The foregoing features of the present embodiment can be information is not contained, the radio base station eNodeB expressed as follows. performs failure processing for the CSFB procedure (PSHO A first feature of the present embodiment is a mobile com procedure) in step S606. 30 munication method including the steps of transmitting an Here, the processing in step S602 may be omitted. In this “Extended Service Request (a start request signal for circuit case, the radio base station eNodeB may be configured to switched type of communications) from a mobile station transmit a “UE Context Modification Response' to the mobil UE in Idle mode (for example, a prioritized mobile station UE ity management node MME in step S3013 when the radio that is about to perform processing for an originating call to a base station eNodeB receives a “UE Context Modification 35 prioritized mobile station UE or a non-prioritized mobile Request.” station UE, or a prioritized mobile station UE or a non Secondly, a second example of the priority control process prioritized mobile station UE that is about to perform pro ing for a “UE Context Modification Request' is described in cessing of a terminating call from a prioritized mobile station reference to FIG. 11. UE) to a mobility management node MME via a radio base As shown in FIG. 11, when the radio base station eNodeB 40 station eNodeB (a radio access networkapparatus) of the LTE receives a “UE Context Modification Request” in step S701, system (a first communication system that does not Support the radio base station eNodeB determines whether or not the circuit-switched type of communications) ; transmitting an priority call information is contained in the “UE Context “Initial UE Context Setup Request (a radio bearer setup Modification Request” in step S702. request signal) from the mobile station UE to the radio base When determining that the priority call information is not 45 station eNodeB, the “Initial UE Context Setup Request con contained, the radio base station eNodeB continues the CSFB taining priority call information and requesting setup of an procedure (PSHO procedure) in step S703. Specifically, in E-RAB (a radio bearer of the first communication system) step S3013 shown in FIG. 9, the radio base station eNodeB between the mobile station UE and the radio base station transmits the “UE Context Modification Response' to the eNodeB; and preferentially allocating resources to the mobility management node MME. 50 E-RAB for the mobile station UE by the radio base station On the other hand, when determining that the priority call eNodeB based on the priority call information contained in information is contained, the radio base station eNodeB the received “Initial UE Context Setup Request.” determines whether or not the resources necessary for RAB In the first feature of the present embodiment, the method setup on the relocation target RAT, i.e., on UTRAN are avail may include the steps of: after the E-RAB for the mobile able in step S704. 55 station UE is set up, transmitting a “Handover Required/ When determining that such resources are available, the Forward Relocation Request (handover request signal)” con radio base stationeNodeB continues the CSFB procedure (PS taining the priority call information from the radio base sta HO procedure) in step S705. Specifically, in step S3013, the tion eNodeB to a packet switch SGSN of a 2G/3G system (a radio base station eNodeB transmits the “UE Context Modi second communication system that Supports circuit-switched fication Response' to the mobility management node MME. 60 type of communications) via the mobility management node On the other hand, when determining that such resources MME; transmitting a “Relocation Request (handover request are not available, the radio base station eNodeB aborts the signal) containing the priority call information from the CSFB procedure (PSHO procedure) and transitions to the packet switch SGSN to a radio network controller RNC (a “Release with Redirection procedure” in step S706. radio access network apparatus of the second communication In the “Release with Redirection procedure, for example, 65 system); and preferentially allocating resources to a RAB (a the radio base station eNodeB may send the mobility man radio bearer of the second communication system) between agement node MME a “UE Context Modification Response' the mobile station UE and the radio network controller RNC US 8,428,035 B2 13 14 by the radio network controller RNC based on the priority call resources to the E-RAB for the mobile station UE based on information contained in the received “Relocation Request.” the priority call information contained in the received “Initial In the first feature of the present embodiment, the method UE Context Setup Request.” may include the steps of: after the resources are allocated to A fourth feature of the present embodiment is a radio base the RAB for the mobile station UE, transmitting a “Reloca station eNodeB Summarized as being configured to: send a tion Request Acknowledge (a handover request acknowledge mobility management node MME an “Extended Service signal) containing the priority call information from the Request' received from a mobile station having an E-RAB radio network controller RNC to the packet switch SGSN: already set up between the mobile station UE and the radio transmitting a “Forward Relocation Response/Handover base station eNodeB (that is, a mobile station UE in Active 10 mode) ; determine whether or not there are available Command (a handover request signal) containing the prior resources in the 2G/3G system in response to a “UE Context ity call information from the packet switch SGSN to the radio Modification Request received from the mobility manage base station eNodeB via the mobility management node ment node MME; and perform E-RAB release processing if MME; transmitting a “HO from E-UTRAN Command (a priority call information is contained in the “UE Context handover request signal) containing the priority call infor 15 Modification Request even when there are not available mation from the radio base station eNodeB to the mobile resources in the 2G/3G system. station UE; and transmitting a “Handover to UTRAN Com A fifth feature of the present embodiment is a radio net plete (a handover request signal acknowledge signal) from work controller RNC summarized as being configured to: the mobile station UE to the radio network controller RNC if after an E-RAB between a mobile station UE and a radio base the priority call information is contained in the received “HO station eNodeB is set up, receive a “Forward Relocation from E-UTRAN Command even though an access to the Request containing priority call information from the radio 2G/3G system is restricted. base station eNodeB via a mobility management node MME In the first feature of the present embodiment, the method and a packet switch SGSN; and preferentially allocate may include the steps of: after the resources are allocated to resources to a RAB between the mobile station UE and the the RAB for the mobile station UE, transmitting a “Reloca 25 radio network controller RNC based on the priority call infor tion Request Acknowledge” containing the priority call infor mation contained in the received “Relocation Request.” mation from the radio network controller RNC to the packet A sixth feature of the present embodiment is a mobile switch SGSN; transmitting the “Forward Relocation station UE Summarized by being configured to: transmit an Response/Handover Command containing the priority call “Extended Service Request' to a mobility management node information from the packet switch SGSN to the radio base 30 MME via a radio base station eNodeB; and transmit a "Han station eNodeB via the mobility management node MME: dover to UTRAN Complete' to a radio network controller transmitting the “HO from E-UTRAN Command” contain RNC if priority call information is contained in a "HO from ing the priority call information from the radio base station E-UTRAN Command received from the radio base station eNodeB to the mobile station UE; transmitting the “Handover eNodeB, even though an access to the 2G/3G system is to UTRAN Complete' containing the priority call informa 35 restricted. tion from the mobile station UE to the radio network control It should be noted that the aforementioned operations of ler RNC; and preferentially accepting the “Handover to the mobile station UE, the radio base station eNodeB, the UTRAN Complete” by the radio network controller RNC radio network controller RNC, the mobility management based on the priority call information contained in the node MME, the gateway device P-GW, the gateway device received “Handover to UTRAN Complete.” 40 S-GW, the circuit switching device MSC, and the packet A second feature of the present embodiment is a mobile switch SGSN may be implemented by hardware, may be, communication method Summarized as including the steps implemented by a software module executed by a processor, of transmitting an “Extended Service Request' from a or may be implemented by a combination of the two. mobile station UE having an E-RAB already set up between A Software module may be provided in a storage medium the mobile station UE and a radio base station eNodeB (that 45 in any format such as a RAM (Random Access Memory), a is, a mobile station UE in Active mode) to a mobility man flash memory, a ROM (Read Only Memory), an EPROM agement node MME via the radio base station eNodeB; trans (Erasable Programmable ROM), an EEPROM (Electroni mitting a “UE Context Modification Request (a setting modi cally Erasable and Programmable ROM), a register, a hard fication request signal) containing priority call information disk, a removable disk, or a CD-ROM. from the mobility management node MME to the radio base 50 Such storage medium is connected to a processor in Such a station eNodeB; determining by the radio base station eNo way that the processor can write and read information to and deB whether or not there are available resources in the 2G/3G from the storage medium. Instead, the storage medium may system in response to the received “UE Context Modification be integrated in the processor. Alternatively, the storage Request:” and even when it is determined that there are not medium and the processor may be integrated in an ASIC. The available resources in the 2G/3G system, performing process 55 ASIC may be provided in the mobile station UE, the radio ing of releasing the E-RAB by the radio base station eNodeB base station eNodeB, the radio network controller RNC, the if the priority call information is contained in the “UE Context mobility management node MME, the gateway device P-GW. Modification Request.” the gateway device S-GW, the circuit switching device MSC, A third feature of the present embodiment is a radio base or the packet switch SGSN. Moreover, the storage medium station eNodeB Summarized as being configured to: transmit 60 and the processor may be provided as discrete components in an “Extended Service Request received from a mobile sta the mobile station UE, the radio base station eNodeB, the tion UE in Idle mode to a mobility management node MME; radio network controller RNC, the mobility management receive an “Initial UE Context Setup Request' from the node MME, the gateway device P-GW, the gateway device mobility management node MME, the “Initial UE Context S-GW, the circuit switching device MSC or the packet switch Setup Request containing priority call information and 65 SGSN. requesting setup of an E-RAB between the mobile station UE Although the present invention have been hereinabove and the radio base station eNodeB; and preferentially allocate described in detail by using the foregoing embodiment, it is US 8,428,035 B2 15 16 apparent to those skilled in the art that the present invention preferentially allocating resources to a radio bearer of the should not be limited to the embodiment specified in the second communication system between the mobile sta present description. The present invention can be imple tion and the radio access network apparatus of the sec mented as altered or modified embodiments without depart ond communication system, by the radio access network ing from the gist and scope of the present invention. There apparatus of the second communication system based on fore, the statement in this description is for illustrative the notified priority call information. purpose, and is not intended to impose any limitation on the 2. A radio access network apparatus of a first communica present invention. tion system that does not support circuit-switched type of communications, wherein the radio access network apparatus is configured to send a INDUSTRIAL APPLICABILITY 10 mobility management node a start request signal for circuit-switched type of communications received from According to the present invention, provided are a mobile a mobile station, and communication method, a radio access network apparatus when receiving a radio bearer setup request signal from the and a mobile station which enable preferential establishment mobility management node which received the start of an E-RAB and a RAB as packet bearers in a CSFB proce 15 request signal and determined that a circuit-switched dure for communication to be prioritized such as an originat fallback procedure is to be prioritized, the radio bearer ing call or a terminating call from a prioritized mobile station, setup request signal containing priority call information and enable priority control for an RRC signal in the CSFB and requesting setup of a radio bearer of the first com procedure, as described above. munication system between the mobile station and the radio access network apparatus of the first communica EXPLANATION OF REFERENCE NUMERAL tion system, the radio access network apparatus notifies a radio access network apparatus of a second communi eNodeB ... radio base station cation system of the priority call information via the MME . . . mobility management node mobility management node and a packet switch of the UE . . . mobile station 25 second communication system, the second communica P-GW. S-GW ... gateway device tion system supporting circuit-switched type of commu MSC . . . circuit switching device nications. SGSN. . . packet switch 3. A mobility management node, wherein RNC. ... radio network controller the mobility management node is configured to receive a 30 The invention claimed is: start request signal for circuit-switched type of commu 1. A mobile communication method comprising the steps nications from a mobile station via a radio access net of: Work apparatus of a first communication system that transmitting a start request signal for circuit-switched type does not support circuit-switched type of communica of communications from a mobile station to a mobility tions, and management node via a radio access network apparatus 35 the mobility management node determines whether or not of a first communication system that does not support to send the radio access network apparatus of the first circuit-switched type of communications; communication system a radio bearer setup request sig transmitting a radio bearer setup request signal from the nal containing priority call information and requesting mobility management node to the radio access network setup of a radio bearer of the first communication system apparatus of the first communication system, the radio 40 between the mobile station and the radio access network bearer setup request signal containing priority call infor apparatus of the first communication system when the mation and requesting setup of a radio bearer of the first mobility management node receives the start request communication system between the mobile station and signal and determines that a circuit-switched fallback the radio access network apparatus of the first commu procedure is to be prioritized. nication system when the mobility management node 45 4. The mobility management node according to claim 3, receives the start request signal and determines that a wherein circuit-switched fallback procedure is to be prioritized; the mobility management node determines whether or not notifying, by the radio access network apparatus of the first a circuit-switched fallback procedure is to be prioritized, communication system, a radio access network appara based on at least one of connection cause information tus of a second communication system of the priority 50 and connection type information contained in the start call information via the mobility management node and request signal for circuit-switched type of communica a packet switch of the second communication system, tions, and subscriber profile information held by the the second communication system supporting circuit mobility management node. Switched type of communications; and ck k sk k k