Methods and apparatus for controlling circuit switched fall back of a mobile station from E-UTRAN to UTRAN/GERAN in a full-multi-operator core network

Packet Switched (PS) handover based Circuit Switched Fall Back (CSFB) of a mobile station is controlled from an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) cell to a target Universal Terrestrial Radio Access Network (UTRAN) cell or a target GSM EDGE Radio Access Network (GERAN) cell in a PS domain. A network node receives a handover request from a SGSN. A PLMN ID associated with the SGSN is identified. A set of PLMN IDs transmitted as system information by the target UTRAN cell or the target GERAN cell is identified. A PLMN ID index is generated to indicate an association between the PLMN ID associated with the SGSN and one of the PLMN IDs of the set. The PLMN ID index is communicated toward the mobile station for use during PS handover based CSFB. The mobile station embeds the PLMN ID index in a Location Area Update (LAU) message, and transmits the LAU message to a target BSS/RNS of the GERAN/UTRAN cell for use during the PS handover based CSFB.

TECHNICAL FIELD

The present disclosure relates to radio access networks and, more particularly, to circuit switched fallback in a multi-operator core network.

BACKGROUND

With the introduction of the FULL-Multi-Operator Core Network (FULL-MOCN) feature a common radio access network (RAN, e.g. a BSS) will be shared by multiple Mobile Switching Centres (MSCs) and/or Serving GPRS Support Nodes (SGSNs), where each MSC and/or SGSN is associated with a different Public Land Mobile Network (PLMN) identified using a unique PLMN ID value. When a Mobile Station (MS) is operating in an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) service area and is attached to the UTRAN or GSM EDGE Radio Access Network (GERAN) Circuit Switched (CS) domain, a CS fallback (CSFB) from E-UTRAN access to the UTRAN/GERAN CS domain access may become necessary if the MS cannot initiate an IMS voice session because it is either not IMS registered or IMS voice services are not supported in the E-UTRAN service area. CSFB operations are described in the standards document 3GPP TS (Technical Specification) 23.272. CSFB may be performed using PS Handover to the target UTRAN/GERAN service area (i.e., PS Handover based CSFB is triggered) where the target service area supports FULL-MOCN operation.

PS Handover based CSFB can be used in a scenario wherein the serving E-UTRAN core network may select a target UTRAN/GERAN cell that is associated with a Location Area (LA) which is different from one stored in the MS. Note that a change in LA will typically be experienced for PS handover based CSFB since it involves a change in RAT (radio access technology). Consequently, the MS will initiate a Location Area Update (LAU) procedure upon arrival in the target UTRAN/GERAN cell.

As part of the LAU procedure, the MS transmits a LAU REQUEST message to the target RAN. The target RAN is responsible for forwarding the LAU REQUEST message to the correct Mobile Switching Centre (MSC) based on the PLMN ID that was selected by the serving E-UTRAN core network (during the PS Handover procedure) for use by the MS upon its arrival in the target UTRAN/GERAN service area. Thus, the MSC to which the target RAN forwards the LAU REQUEST message should be the MSC associated with the selected PLMN ID. However, this becomes problematic for PS handover based CSFB to a target cell supporting FULL-MOCN since for this scenario there will be no process for the target RAN to determine the MSC to which it should forward the LAU REQUEST message because it will not be able to associate the MS sending this message with any specific PLMN.

For the non-handover scenario where an MS is able to read system information prior to sending the LAU REQUEST message, the Skip Indicator Information Element included in this message is used to provide the target RAN with the information it needs to determine the MSC to which it is to forward the LAU REQUEST message, i.e., it contains an indication of the selected PLMN ID. Prior to sending a LAU REQUEST message, the MS has knowledge of the set of PLMNs supported by its current serving cell (indicated by system information sent in the serving cell) whenever MOCN operation is supported. Therefore, for the non-handover scenario, the MS is able to use this information to set the value of the Skip Indicator included in the LAU REQUEST message to reflect the desired PLMN ID.

However, for the case of PS Handover based CSFB described above, there is no way for the MS to determine the PLMN selected for it to use in the target cell nor the set of PLMNs supported in the target cell. The MS is therefore unable to populate the Skip Indicator with information that the target RAN needs to use to correctly forward the LAU REQUEST message. With inaccurate/invalid information present within the Skip Indicator there is a high risk that the target RAN will forward the LAU REQUEST message to a MSC that is not associated with the PLMN selected for use by the MS, which may result in the MS receiving less than optimal service. For example, the MS may be billed excessively for all CS calls made while being served by the less preferred PLMN.

SUMMARY

To address the foregoing problems identified in the prior art, the Detailed Description presented hereinafter will describe several systems and methods directed to controlling CSFB of a mobile station from an E-UTRAN serving cell to a target UTRAN cell or a target GERAN cell in a CS domain.

One embodiment is directed to a method in a radio telecommunications network for controlling Packet Switched (PS) handover based CSFB of the mobile station. The method includes receiving a handover request from a SGSN. A PLMN ID associated with the SGSN is identified responsive to the handover request. A set of a plurality of PLMN IDs transmitted as system information by the target UTRAN cell or the target GERAN cell is identified. A PLMN ID index is generated that indicates an association between the PLMN ID associated with the SGSN and one of the PLMN IDs of the set. The PLMN ID index is communicated toward the mobile station for use during the PS handover based CSFB.

The PLMN ID index may be communicated to the mobile station through a handover command message. Upon moving to the target UTRAN cell or the target GERAN cell and completing the PS handover based CSFB, the mobile station establishes a CS connection and determines that a LAU is required. It then embeds the received PLMN ID index in a Location Area Update (LAU) message that it transmits in the target UTRAN cell or target GERAN cell. A target RAN serving the target UTRAN cell or target GERAN cell receives the LAU message and can use the PLMN ID index included therein to identify the MSC that is associated with the PLMN ID index, which can result in the MS receiving improved service.

Another embodiment is directed to a method by a mobile station for controlling PS handover based CSFB of the mobile station from a E-UTRAN serving cell to a target UTRAN cell or a target GERAN cell in a PS domain. An extended service request message is transmitted by the MS to the eNodeB of the E-UTRAN serving cell. A handover command message is received from the eNodeB of the E-UTRAN serving cell responsive to the extended service request message, where the handover command contains a PLMN ID index. The PLMN ID index is embedded in a Location Area Update, LAU, message. The LAU message is transmitted in one of the UTRAN cell or the GERAN cell to which the MS was directed by the handover command message.

As explained above, because the mobile station receives a PLMN ID index as part of the handover command message, it can retain knowledge of this information and is therefore able to include the PLMN ID index in Layer 3 messages sent to the target BSS or target RNS upon establishing a CS connection in the target GERAN cell or target UTRAN cell after completion of the handover execution phase of the PS handover based CSFB procedure. The target BSS or target RNS can thereby identify the MSC that is associated with the PLMN selected for use by the mobile station, which can result in the MS receiving improved service.

Another embodiment is directed to a network node for controlling PS handover based CSFB of a mobile station from an E-UTRAN serving cell to a target UTRAN cell or a target GERAN cell in a PS domain. The network node comprises at least one processor and at least one memory coupled to the at least one processor and comprising computer readable program code that when executed by the at least one processor causes the at least one processor to perform operations that include receiving a handover request from a SGSN, identifying a PLMN ID associated with the SGSN responsive to the handover request, identifying a set of a plurality of PLMN IDs transmitted as system information by the target UTRAN cell or the target GERAN cell, generating a PLMN ID index that indicates an association between the PLMN ID associated with the SGSN and one of the PLMN IDs of the set, and communicating the PLMN ID index toward the mobile station for use during PS handover based CSFB.

Another embodiment is directed to a mobile station for controlling PS handover based CSFB of the mobile station from a E-UTRAN serving cell to a target UTRAN cell or a target GERAN cell in a PS domain. The mobile station comprises at least one processor and at least one memory coupled to the at least one processor and comprising computer readable program code that when executed by the at least one processor causes the at least one processor to perform operations that include transmitting an extended service request message to an eNodeB of the E-UTRAN serving cell, receiving a handover command message from the eNodeB of the E-UTRAN serving cell responsive to the extended service request message, where the handover command contains a PLMN ID index, embedding the PLMN ID index in a LAU message, and transmitting the LAU message in one of the UTRAN cell or the GERAN cell to which the MS was directed by the handover command message.

Other methods, network nodes, and mobile stations according to embodiments of the invention will be or become apparent to one with skill in the art upon review of the following drawings and detailed description. It is intended that all such additional methods, network nodes, and mobile stations be included within this description, be within the scope of the present invention, and be protected by the accompanying claims. Moreover, it is intended that all embodiments disclosed herein can be implemented separately or combined in any way and/or combination.

DETAILED DESCRIPTION

The invention will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. The invention may, however, be embodied in many different forms and is not to be construed as limited to the embodiments set forth herein.

One or more of foregoing problems identified in the prior art may be overcome by various embodiments disclosed herein. Some embodiments are disclosed in the context of an example Third Generation Partnership Project (3GPP) radio telecommunications network shown inFIG. 1which performs a PS Handover based CSFB procedure that is modified relative to that disclosed in 3GPP TS 23.272. An overview of the network ofFIG. 1is initially provided, and then various operations according to embodiments disclosed herein are explained in the context of the network ofFIG. 1. Although various embodiments are disclosed in the context of the network ofFIG. 1, the invention is not limited thereto.

The radio telecommunications network comprises a plurality, typically thousands, of mobile stations (MSs)100(also known as user equipment nodes, wireless terminals, or mobile stations) that communicate through radio access communication links with a UTRAN110, a GERAN120, and/or an E-UTRAN130.

The UTRAN110/GERAN120can include radio network controller (RNC)/base station controller (BSC) nodes to control communications through radio base station nodes providing radio access communication links to MSs100that are within their respective communication service cells. The E-UTRAN130can include radio base station nodes (eNodeBs) that can provide the combined functionality of the RNC/BSC nodes of the UTRAN110/GERAN120.

A plurality of SGSNs140(one of which is shown inFIG. 1) are responsible for the delivery of data packets from and to the MSs100within their geographical service area. Their tasks can include packet routing and transfer, mobility management (attach/detach and location management), logical link management, and authentication functions. The SGSNs140control communications connections between MSs100and one or more packet-based networks, and may perform other functions such as mobility management of MSs100. Mobility Management Entities (MMEs)150(one of which is shown inFIG. 1) and the SGSNs140provide control plane functionality to enable mobility of MSs100between the UTRAN110, the GERAN120, and the E-UTRAN130via the S3 interface between the MMEs150and the SGSNs140.

The MMEs150route and forward signalling packets for the E-UTRAN130, and are responsible for EPS Connection Management (ECM) idle mode MS100tracking and paging procedures, and are involved in connection bearer (Packet Data Network (PDN) connection) activation/deactivation processes, for choosing a Serving Gateway (SGW) for a MS100at the initial attachment and at time of handover.

In one embodiment, one or more network nodes (e.g., base station subsystem (BSS), radio network subsystem (RNS), MME, MSC, SGSN, etc.) of the radio telecommunications network controls Packet Switched (PS) handover based CSFB of a MS100from the E-UTRAN serving cell130to the target UTRAN cell110or the target GERAN cell120in a PS domain. A PS handover request is received from the SGSN140. A Public Land Mobile Network (PLMN) ID associated with the SGSN140is identified responsive to the PS handover request. A set of a plurality of PLMN IDs transmitted as system information by the target UTRAN cell110or the target GERAN cell120is identified. A PLMN ID index is generated that indicates an association between the PLMN ID associated with the SGSN140and one of the PLMN IDs of the set.

The PLMN ID index is then communicated toward the MS100for use during PS handover based CSFB. The PLMN ID index can be communicated to the MS100through a handover command message. Upon moving to the target UTRAN cell110or the target GERAN cell120, completing the handover and establishing a CS connection in the target cell, the MS100determines that a Location Area Update, LAU, is needed and embeds the received PLMN ID index in a LAU message that it transmits in the target UTRAN cell110/target GERAN cell120to which the MS100was directed by the handover command message. A RNC/BSC of the target UTRAN cell110/target GERAN cell120receiving the LAU message can use the PLMN ID index to identify the MSC160that is associated with the PLMN selected for use by the MS100, which can result in the MS receiving improved service.

These and further operations, methods and associated message flows between various network nodes of the radio telecommunications network are explained below with reference toFIG. 2. Some steps ofFIG. 2may be performed as described in 3GPP TS 23.272 (e.g., FIG.6.2.1) and as described in 3GPP TS 23.401 (e.g., FIG.5.5.2.3.3-1).

Referring to step200ofFIG. 2, the MS100is operating in, and serviced by, a source eNodeB102of the E-UTRAN serving cell130. The MS100sends an Extended Service Request200for mobile originating CS fallback to the source MME150(via the eNodeB102). The UE100only transmits this request if it is attached to CS domain (with a combined Evolved Packet System (EPS)/IMSI Attach) and cannot initiate an IMS voice session because, for example, the UE100is not IMS registered or IMS voice services are not supported by the serving IP-Connectivity Access Network (IP-CAN), home PLMN or MS100.

In steps202-210, the source eNodeB102triggers PS handover to the target GERAN cell120or the target UTRAN cell110by sending a Handover Required message (S1AP Cause, Target System Identifier, Source to Target Transparent Container) to the source MME150. The source eNodeB102selects the target PS handover cell (e.g., among one or a plurality of the target GERAN cells120or the target UTRAN cells110) responsive to the PLMN ID and possibly further responsive to the LAI for CS domain provided by the source MME150.

More particularly, in step202the source MME150sends an S1-AP MS Context Modification Request (CS Fallback Indicator, LAI) message to the source eNodeB102. This message indicates to the source eNodeB102that the MS100should be moved to UTRAN/GERAN. The registered PLMN for CS domain is identified by the PLMN ID included in the LAI, which is allocated by the source MME150. In step204, source eNodeB102replies with a S1-AP UE Context Modification Response message, and then communicates, in step206, a Handover Required Message to the source MME150.

In step208, the source MME150determines from the “Target System Identifier” IE that the type of handover is IRAT Handover to GERAN/U IRAN. For the case where the target RAT is GERAN the source MME150initiates a handover resource allocation procedure by sending a Forward Relocation Request (IMSI, Target Identification (shall be set to “empty”), MM Context, PDN Connections, MME Tunnel Endpoint Identifier for Control Plane, MME Address for Control plane, Source to Target Transparent Container, Packet Flow ID, XID parameters (if available), Target Cell Identification, MS Info Change Reporting Action (if available), CSG Information Reporting Action (if available), UE Time Zone, ISR Supported, RAN Cause, Serving Network) message to the target SGSN140.

For brevity, various further operations ofFIG. 2are explained in the context of PS handover based CSFB to the GERAN cell120, although similar operations can be performed for CSFB to the UTRAN cell110. Accordingly, these and other embodiments are not necessarily limited to PS handover based CSFB to a GERAN cell.

In step210, the target SGSN140requests a target BSS104of the GERAN cell120to establish the necessary resources (PFCs) by sending the message PS Handover Request (Local TLLI, IMSI, Cause, Target Cell Identifier, PFCs to be set-up list, Source BSS to Target BSS Transparent Container and NAS container for handover). It is noted that if the PS handover based CSFB were to a UTRAN cell110, the target SGSN140would send a handover request message to a target Radio Network Subsystem (RNS)104.

The target BSS104allocates the requested resources and communicates (step212) the applicable parameters to the target SGSN140in the message PS Handover Request Acknowledge (Local TLLI, List of set-up PFCs, Target BSS to Source BSS Transparent Container, Cause). The target BSS104contains information informing that FULL-MOCN operation is supported, and thereby determines that PLMN ID Index information may be required by the MS100when the MS100arrives in the target GERAN cell120as a result of a PS Handover from the E-UTRAN serving cell130to the target GERAN cell120.

The target BSS104identifies (step230) the PLMN ID associated with the target SGSN140from which it receives the PS Handover Request (i.e. the target (selected) PLMN ID) and further identifies (step232) a set of a plurality of PLMN IDs transmitted as part of system information (SI) in the target GERAN cell120, and is configured to generate therefrom (step234) a “PLMN ID Index” corresponding to the target PLMN ID. In step212, the target BSS104communicates the generated PLMN ID Index as part of a PS Handover Request Ack message to the target SGSN140.

In one embodiment, the target BSS104is configured to determine (generate) the PLMN ID index to indicate an association between the PLMN ID associated with the SGSN140and one of the PLMN IDs of the set. In a further embodiment, the set of the PLMN IDs comprises an ordered list of PLMN IDs, and the target BSS104determines (generates) the PLMN ID index in response to the location of the PLMN ID associated with the SGSN in the ordered list of PLMN IDs. For example, when the target PLMN ID is the third PLMN ID occurring in the list of PLMN IDs transmitted as part of System Information (SI) in the target cell, the target BSS104sets the PLMN ID Index to 3.

It is noted that when a GWCN (Gateway Core Network) architecture is used in which SGSNs and MSCs are shared by multiple PLMNs, the SGSN140indicates the target (selected) PLMN ID in a new Information Element in the PS Handover Request message sent to the target BSS in step210. The target BSS104contains information identifying the set of PLMN IDs transmitted as part of SI in the target cell, and is configured to determine (generate) a “PLMN ID Index” corresponding to the target PLMN ID.

The target BSS104includes (embeds) the “PLMN ID Index” as new information within the “Target BSS to Source BSS Transparent Container” message that is communicated to the target SGSN140in the PS Handover Request Ack message212. The container is part of the Radio Network information (see section 5.6.1.8.2 of 3GPP TS 43.129) carried by “Target BSS to Source BSS Transparent Container” and is sent transparently to the MS100(i.e. the source eNodeB102passes this information directly to the MS100as part of the PS Handover procedure).

In step214, the target SGSN140sends (e.g., forwards) the message Forward Relocation Response (Cause, SGSN Tunnel Endpoint Identifier for Control Plane, SGSN Address for Control Plane, Target to Source Transparent Container, RAN Cause, List of set-up PFIs, Address(es) and TEID(s) for User Traffic Data Forwarding, Serving GW change indication) to the source MME150. The Target to Source Transparent Container includes the PLMN ID Index carried within the Target BSS to Source BSS Transparent Container received from the target BSS104.

In step216, the source MME150performs further PS Handover preparation and sends the message Handover Command (Target to Source Transparent Container (PS Handover Command with RN part and EPC part), E-RABs to Release List, Bearers Subject to Data Forwarding List), SLAP Cause) to the source eNodeB102. The Handover Command message includes the PLMN ID Index.

In Step218, the source eNodeB sends to the MS100a command message to handover to the Target Access System via the message “HO from E-UTRAN Command” The command message includes a transparent container including Radio Network information (see step212) that the target BSS104has constructed in the preparation phase. The command message includes the PLMN ID Index.

In step220, the MS100executes the handover according to the parameters provided in the “HO from E-UTRAN Command” it received in step218and thereby moves to the target BSS104.

In step222, the MS100arrives in the GERAN cell120, completes the handover execution phase, and if the LA of the target cell is different from the one stored in the MS100, the MS100responds by initiating a Location Area Update or a Combined RA/LA Update procedure. If the network is operating in NMO-I (Network Mode of Operation I), the MS100may initiate a separate Location Area Update (LAU) before initiating the RAU procedure instead of a Combined RA/LA Update procedure (to speed up the PS handover based CSFB procedure). Alternatively, if the network is operating in NMO-II or NMO-III, the MS100initiates a Location Area Update before initiating the RAU procedure required for PS handover.

In accordance with various embodiments, in step222, the MS100embeds the PLMN ID Index, which was received as part of the “HO from E-UTRAN Command” in step218, into the LAU message that is transmitted to the target BSS104. In a further embodiment, the MS100embeds the PLMN ID Index in a “Skip Indicator” IE of the LAU message that it transmits to the target BSS104.

The target BSS104identifies the PLMN ID Index received with the LAU message, such as by looking at a value of the Skip Indicator IE of the LAU message, and determines therefrom which MSC is to be associated with the MS100. The target BSS104may forward the LAU message to a MSC160that is identified by the PLMN ID index of the LAU message. The MS100, the BSS104, and the MSC160can then perform further operations to complete CS call setup, step224, which may occur according to known 3GPP standards processes.

Related Operations and Methods by a Radio Telecommunications Network for Controlling PS handover based CSFB

FIGS. 3-10illustrate flowcharts of related operations and methods by a radio telecommunications network according to some related embodiments. The operations and methods may be performed by, for example, a BSS, a RNS, a MME, a SGSN, and/or a MSC.

FIG. 3illustrates operations and methods by the radio telecommunications network for controlling PS handover based CSFB of a MS from a E-UTRAN serving cell to a target UTRAN cell or a target GERAN cell in a PS domain. A handover request is received (step300) from a SGSN. The handover request may be a PS handover request. A PLMN ID associated with the SGSN is identified (step302) responsive to the handover request. A set of a plurality of PLMN IDs transmitted as system information by the target UTRAN cell or the target GERAN cell is identified (step304). The set of the PLMN IDs can include PLMN IDs of a plurality of different operators of a FULL-Multi-Operator Core Network (FULL-MOCN). A PLMN ID index is generated (step306) that indicates an association between the PLMN ID associated with the SGSN and one of the PLMN IDs of the set. The PLMN ID index is communicated (step308) in a handover command sent to the MS during the PS handover based CSFB.

In a related embodiment ofFIG. 4, a Location Area Update (LAU) message is received (step400) from the MS. The LAU message contains the PLMN ID index. A MSC160is selected (step402) responsive to the PLMN ID index.

FIG. 5is a related embodiment toFIG. 4, in which the PLMN ID index is identified (step500) from a skip indicator information element of the LAU message.

FIG. 6is a related embodiment toFIG. 4, in which selection (step402) of a MSC160includes selecting (step600) one of the PLMN IDs transmitted as system information by the target UTRAN cell or the target GERAN cell responsive to the PLMN ID index of the LAU message.

FIG. 7is a related embodiment toFIG. 4, in which the LAU message is forwarded (step700) to a Mobile Switching Centre, MSC, that corresponds to the PLMN ID index of the LAU message.

FIG. 8is a related embodiment toFIG. 1, where the set of the PLMN IDs (step304) can include an ordered list of PLMN IDs. The PLMN ID index can be generated (800) in response to the location of the PLMN ID associated with the SGSN in the ordered list of PLMN IDs.

FIG. 9is a related embodiment toFIG. 8, where communication (step308) of the PLMN ID index toward the MS for use during PS handover based CSFB, can include embedding (step900) the PLMN ID index as an information item in a handover command message. The handover command message is communicated (step902) toward the MS.

FIG. 10is a related embodiment toFIG. 1, where embedding (step900) the PLMN ID index as an information element in a handover command message can include embedding (step1000) the PLMN ID index in a Target BSS to Source BSS Transparent Container carried within the handover command message.

Related Operations and Methods by a Mobile Station

FIGS. 11-13illustrate flowcharts of related operations and methods by a MS according to some related embodiments.

FIG. 11illustrates operations and methods by the MS for controlling PS handover based CSFB of the MS from a E-UTRAN serving cell to a target UTRAN cell or a target GERAN cell in a CS domain. Referring toFIG. 11, an extended service request message is transmitted (step1100) to an eNodeB of the E-UTRAN serving cell. A handover command message is received (step1102) from the eNodeB of the E-UTRAN serving cell responsive to the extended service request message, where the handover command contains a PLMN ID index. After completing the handover execution phase of a PS handover based CSFB, the mobile station establishes a CS connection and determines that a LAU update is required. The PLMN ID index is embedded (step1104) in a Location Area Update (LAU) message. The LAU message is transmitted (step1106), with the PLMN ID index, in one of the UTRAN cell or the GERAN cell to which the mobile station was directed by the handover command message. The PLMN ID index can identify a PLMN ID of one of a plurality of different operators of a FULL-Multi-Operator Core Network (FULL-MOCN).

FIG. 12is a related embodiment toFIG. 11, where receiving (step1102) the handover command message from the eNodeB of the E-UTRAN serving cell can include extracting (step1200) the PLMN ID index from a transparent container carried within the handover command message, which can be a Target BSS to Source BSS Transparent Container.

FIG. 13is a related embodiment toFIG. 11, where embedding (step1104) the PLMN ID index in the LAU message can include embedding (step1300) the PLMN ID index in a skip indicator information element of the LAU message.

Example Network Node/Mobile Station

FIG. 14is a block diagram of a network node or mobile station1400that is configured according to some embodiments. The network node or mobile station1400may be used as one or more of the elements ofFIGS. 1 and 2, including, but not limited, to the MS100, eNodeB102, the BSS/RNS104, the MME150, the MSC160, or the SGSN150. The network node or mobile station1400can include one or more network interfaces1430, processor circuitry1410, and memory devices1420that contain functional modules1422.

The processor circuitry1410may include one or more data processing circuits, such as a general purpose and/or special purpose processor (e.g., microprocessor and/or digital signal processor) that may be collocated or distributed across one or more networks. The processor circuitry1410is configured to execute computer program instructions from the functional modules1422in the memory devices1420, described below as a computer readable medium, to perform some or all of the operations and methods that are described above for one or more of the embodiments, such as the embodiments ofFIGS. 1-13. Accordingly, the processor circuitry1410can be configured by execution of the computer program instructions in the functional modules1422to carry out at least some of the functionality described herein to control PS handover based CSFB of a mobile station from an E-UTRAN serving cell to a target UTRAN cell or a target GERAN cell in a PS domain.

ABBREVIATIONS

A list of abbreviations used in the present disclosure is provided below for ease of reference of the reader:3GPP Third Generation Partnership ProjectBSC Base Station ControllerBSS Base Station SubsystemCS Circuit SwitchedCSFB Circuit Switched Fall BackEDGE Enhanced Data rates for GSM EvolutionE-UTRAN Evolved Universal Terrestrial Radio Access NetworkeNodeB E-UTRAN NodeBFULL-MOCN FULL-Multi-Operator Core NetworkGERAN GSM EDGE Radio Access NetworkGPRS General Packet Radio ServiceGWCN Gateway Core NetworkIE Information ElementIMS IP Multimedia SubsystemLAU Location Area UpdateMME Mobility Management EntityMS Mobile StationMSC Mobile Switching CentrePLMN Public Land Mobile NetworkPS Packet SwitchedRNC Radio Network ControllerRNS Radio Network SubsystemSGSN Serving GPRS Support NodeSGW Serving GatewaySI System InformationUMTS Universal Mobile Telecommunications SystemUTRAN UMTS Terrestrial Radio Access Network

Further Definitions and Embodiments

The computer program instructions may also be loaded onto a computer and/or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer and/or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions/acts specified in the block diagrams and/or flowchart block or blocks. Accordingly, embodiments of the present disclosure may be embodied in hardware and/or in software (including firmware, resident software, micro-code, etc.) that runs on a processor such as a digital signal processor, which may collectively be referred to as “circuitry,” “a module” or variants thereof.

Many different embodiments have been disclosed herein, in connection with the above description and the drawings. It will be understood that it would be unduly repetitious and obfuscating to literally describe and illustrate every combination and subcombination of these embodiments. Accordingly, the present specification, including the drawings, shall be construed to constitute a complete written description of various example combinations and subcombinations of embodiments and of the manner and process of making and using them, and shall support claims to any such combination or subcombination.

Many variations and modifications can be made to the embodiments without substantially departing from the principles of the present invention. All such variations and modifications are intended to be included herein within the scope of the present invention.