WO2013166675A1

WO2013166675A1 - Providing packet switched registration information to facilitate handover from a circuit switched network

Info

Publication number: WO2013166675A1
Application number: PCT/CN2012/075261
Authority: WO
Inventors: Shyamal Ramachandran; Xipeng Zhu; Miguel Griot; Ac C. Mahendran; Lenaig G. CHAPONNIERE
Original assignee: Qualcomm Incorporated
Priority date: 2012-05-09
Filing date: 2012-05-09
Publication date: 2013-11-14

Abstract

A method, an apparatus, and a computer program product for wireless communication are provided in which context information from a packet switched network domain is shared between a mobile switching center and mobile management entity. This information is then used to facilitate a reverse single radio voice call continuity procedure for handing over a user equipment from a circuit switched domain to a packet switched domain.

Description

PROVIDING PACKET SWITCHED REGISTRATION INFORMATION TO FACILITATE HANDOVER FROM A CIRCUIT SWITCHED NETWORK

BACKGROUND

Field

[0001] The present disclosure relates generally to communication systems, and more particularly, to a handover between circuit switched and packet switched wireless networks.

Background

[0002] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

[0003] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example of an emerging telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). It is designed to better support mobile broadband Internet access by improving spectral efficiency, lower costs, improve services, make use of new spectrum, and better integrate with other open standards using OFDMA on the downlink (DL), SC-FDMA on the uplink (UL), and multiple- input multiple- output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.

SUMMARY

In an aspect of the disclosure, context information from a packet switched (PS) network domain is shared between a mobile switching center (MSC) and mobile management entity (MME). This information is then used to facilitate a reverse single radio voice call continuity (rSRVCC) procedure for handing over a user equipment (UE) from a circuit switched (CS) domain to a PS domain.

In an aspect of the disclosure, PS registration information is requested from the UE while the UE is associated with a CS network. An identifier may be received from the UE in response to the request. The identifier may be provided to the MME or another network entity. The rSRVCC procedure may then be performed using the identifier. The identifier may comprise one or more of a packet temporary mobile subscriber identity, a routing area identity, a packet temporary mobile subscriber identity signature, and a globally unique temporary identity.

In an aspect of the disclosure, the PS registration information is requested from the UE when the UE is determined to be capable of performing the rSRVCC procedure. The PS registration information may be requested from the UE when the UE is determined to be in need of performing the rSRVCC procedure.

In an aspect of the disclosure, requesting the PS registration information from the UE may include performing a mobility management (MM) procedure. The MM procedure may comprise one or more of a temporary mobile subscriber identity packet temporary mobile subscriber identity reallocation, authentication, identification, an international mobile subscriber identity attach or detach.

In an aspect of the disclosure, requesting the PS registration information from the UE may include performing a call management procedure that may include one or more of one or more of a service request and a reestablish request. Performing the call management procedure comprises exchanging the PS registration information through an upper layer protocol. In an aspect of the disclosure, requesting the PS registration information from the UE may include requesting the registration information using one or more call control signaling procedures.

In an aspect of the disclosure, a request is received at a network entity of a PS network to initiate a rSRVCC procedure. The request may identify a UE associated with a CS network. A home subscriber server (HSS) may be queried for PS registration information of the UE. The rSRVCC procedure may then be performed using the PS registration information of the UE.

In an aspect of the disclosure, the PS registration information comprises one or more of a packet temporary mobile subscriber identity, a routing area identity, a packet temporary mobile subscriber identity signature, and a globally unique temporary identity. The CS network may comprise a global system for mobile communications network. The PS registration information may be requested from the HSS when the UE is determined to be capable of performing the rSRVCC procedure.

In an aspect of the disclosure, querying the HSS includes determining an identifier of a PS domain network identity associated with the UE, and querying the PS network entity for PS domain registration information of the UE.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 is a diagram illustrating an example of a network architecture.

[0014] FIG. 2 is a diagram illustrating an example of an access network.

[0015] FIG. 3 is a diagram illustrating an example of a DL frame structure in LTE.

[0016] FIG. 4 is a diagram illustrating an example of an UL frame structure in LTE.

[0017] FIG. 5 is a diagram illustrating an example of a radio protocol architecture for the user and control planes.

[0018] FIG. 6 is a diagram illustrating an example of an evolved Node B and user equipment in an access network.

[0019] FIG. 7 illustrates a wireless network system having different domains.

[0020] FIG. 8 illustrates a message transmitted in a wireless system.

[0021] FIG. 9 illustrates a message transmitted in a wireless system.

[0022] FIG. 10 includes flow charts of methods of wireless communication. [0023] FIG. 11 is a conceptual data flow diagram illustrating the data flow between different modules/means/components in an exemplary apparatus.

[0024] FIG. 12 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.

DETAILED DESCRIPTION

[0025] The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

[0026] Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

[0027] By way of example, an element, or any portion of an element, or any combination of elements may be implemented with a "processing system" that includes one or more processors. Examples of processors include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

[0028] Accordingly, in one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or encoded as one or more instructions or code on a computer-readable medium. Computer- readable media includes computer storage media. Storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0029] FIG. 1 is a diagram illustrating an LTE network architecture 100. The LTE network architecture 100 may be referred to as an Evolved Packet System (EPS) 100. The EPS 100 may include one or more UE 102, an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN) 104, an Evolved Packet Core (EPC) 110, a HSS 120, and an Operator's IP Services 122. The EPS can interconnect with other access networks, but for simplicity those entities/interfaces are not shown. As shown, the EPS provides packet-switched services, however, as those skilled in the art will readily appreciate, the various concepts presented throughout this disclosure may be extended to networks providing circuit- switched services.

[0030] The E-UTRAN includes the evolved Node B (eNB) 106 and other eNBs 108.

The eNB 106 provides user and control planes protocol terminations toward the UE 102. The eNB 106 may be connected to the other eNBs 108 via a backhaul (e.g., an X2 interface). The eNB 106 may also be referred to as a base station, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), or some other suitable terminology. The eNB 106 provides an access point to the EPC 110 for a UE 102. Examples of UEs 102 include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, or any other similar functioning device. The UE 102 may also be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

[0031] The eNB 106 is connected by an SI interface to the EPC 110. The EPC 110 includes MME 112, other MMEs 114, a Serving Gateway 116, and a Packet Data Network (PDN) Gateway 118. The MME 112 is the control node that processes the signaling between the UE 102 and the EPC 110. Generally, the MME 112 provides bearer and connection management. All user IP packets are transferred through the Serving Gateway 116, which itself is connected to the PDN Gateway 118. The PDN Gateway 118 provides UE IP address allocation as well as other functions. The PDN Gateway 118 is connected to the Operator's IP Services 122. The Operator's IP Services 122 may include the Internet, the Intranet, an IP Multimedia Subsystem (IMS), and a PS Streaming Service (PSS).

[0032] FIG. 2 is a diagram illustrating an example of an access network 200 in an LTE network architecture. In this example, the access network 200 is divided into a number of cellular regions (cells) 202. One or more lower power class eNBs 208 may have cellular regions 210 that overlap with one or more of the cells 202. The lower power class eNB 208 may be a femto cell (e.g., home eNB (HeNB)), pico cell, micro cell, or remote radio head (RRH). The macro eNBs 204 are each assigned to a respective cell 202 and are configured to provide an access point to the EPC 110 for all the UEs 206 in the cells 202. There is no centralized controller in this example of an access network 200, but a centralized controller may be used in alternative configurations. The eNBs 204 are responsible for all radio related functions including radio bearer control, admission control, mobility control, scheduling, security, and connectivity to the serving gateway 116.

[0033] The modulation and multiple access scheme employed by the access network

200 may vary depending on the particular telecommunications standard being deployed. In LTE applications, OFDM is used on the DL and SC-FDMA is used on the UL to support both frequency division duplexing (FDD) and time division duplexing (TDD). As those skilled in the art will readily appreciate from the detailed description to follow, the various concepts presented herein are well suited for LTE applications. However, these concepts may be readily extended to other telecommunication standards employing other modulation and multiple access techniques. By way of example, these concepts may be extended to Evolution-Data Optimized (EV-DO) or Ultra Mobile Broadband (UMB). EV-DO and UMB are air interface standards promulgated by the 3rd Generation Partnership Project 2 (3GPP2) as part of the CDMA2000 family of standards and employs CDMA to provide broadband Internet access to mobile stations. These concepts may also be extended to Universal Terrestrial Radio Access (UTRA) employing Wideband-CDMA (W- CDMA) and other variants of CDMA, such as TD-SCDMA; Global System for Mobile Communications (GSM) employing TDMA; and Evolved UTRA (E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, and Flash-OFDM employing OFDM A. UTRA, E-UTRA, UMTS, LTE and GSM are described in documents from the 3GPP organization. CDMA2000 and UMB are described in documents from the 3GPP2 organization. The actual wireless communication standard and the multiple access technology employed will depend on the specific application and the overall design constraints imposed on the system.

[0034] The eNBs 204 may have multiple antennas supporting MIMO technology. The use of MIMO technology enables the eNBs 204 to exploit the spatial domain to support spatial multiplexing, beamforming, and transmit diversity. Spatial multiplexing may be used to transmit different streams of data simultaneously on the same frequency. The data steams may be transmitted to a single UE 206 to increase the data rate or to multiple UEs 206 to increase the overall system capacity. This is achieved by spatially precoding each data stream (i.e., applying a scaling of an amplitude and a phase) and then transmitting each spatially precoded stream through multiple transmit antennas on the DL. The spatially precoded data streams arrive at the UE(s) 206 with different spatial signatures, which enables each of the UE(s) 206 to recover the one or more data streams destined for that UE 206. On the UL, each UE 206 transmits a spatially precoded data stream, which enables the eNB 204 to identify the source of each spatially precoded data stream.

[0035] Spatial multiplexing is generally used when channel conditions are good. When channel conditions are less favorable, beamforming may be used to focus the transmission energy in one or more directions. This may be achieved by spatially precoding the data for transmission through multiple antennas. To achieve good coverage at the edges of the cell, a single stream beamforming transmission may be used in combination with transmit diversity.

[0036] In the detailed description that follows, various aspects of an access network will be described with reference to a MIMO system supporting OFDM on the DL. OFDM is a spread- spectrum technique that modulates data over a number of subcarriers within an OFDM symbol. The subcarriers are spaced apart at precise frequencies. The spacing provides "orthogonality" that enables a receiver to recover the data from the subcarriers. In the time domain, a guard interval (e.g., cyclic prefix) may be added to each OFDM symbol to combat inter-OFDM-symbol interference. The UL may use SC-FDMA in the form of a DFT-spread OFDM signal to compensate for high peak- to-average power ratio (PAPR).

[0037] FIG. 3 is a diagram 300 illustrating an example of a DL frame structure in LTE.

A frame (10 ms) may be divided into 10 equally sized sub-frames. Each sub-frame may include two consecutive time slots. A resource grid may be used to represent two time slots, each time slot including a resource block. The resource grid is divided into multiple resource elements. In LTE, a resource block contains 12 consecutive subcarriers in the frequency domain and, for a normal cyclic prefix in each OFDM symbol, 7 consecutive OFDM symbols in the time domain, or 84 resource elements. For an extended cyclic prefix, a resource block contains 6 consecutive OFDM symbols in the time domain and has 72 resource elements. Some of the resource elements, as indicated as R 302, 304, include DL reference signals (DL-RS). The DL-RS include Cell-specific RS (CRS) (also sometimes called common RS) 302 and UE-specific RS (UE-RS) 304. UE-RS 304 are transmitted only on the resource blocks upon which the corresponding physical DL shared channel (PDSCH) is mapped. The number of bits carried by each resource element depends on the modulation scheme. Thus, the more resource blocks that a UE receives and the higher the modulation scheme, the higher the data rate for the UE.

[0038] FIG. 4 is a diagram 400 illustrating an example of an UL frame structure in

LTE. The available resource blocks for the UL may be partitioned into a data section and a control section. The control section may be formed at the two edges of the system bandwidth and may have a configurable size. The resource blocks in the control section may be assigned to UEs for transmission of control information. The data section may include all resource blocks not included in the control section. The UL frame structure results in the data section including contiguous subcarriers, which may allow a single UE to be assigned all of the contiguous subcarriers in the data section.

[0039] A UE may be assigned resource blocks 410a, 410b in the control section to transmit control information to an eNB. The UE may also be assigned resource blocks 420a, 420b in the data section to transmit data to the eNB. The UE may transmit control information in a physical UL control channel (PUCCH) on the assigned resource blocks in the control section. The UE may transmit only data or both data and control information in a physical UL shared channel (PUSCH) on the assigned resource blocks in the data section. A UL transmission may span both slots of a subframe and may hop across frequency.

[0040] A set of resource blocks may be used to perform initial system access and achieve UL synchronization in a physical random access channel (PRACH) 430. The PRACH 430 carries a random sequence and cannot carry any UL data/signaling. Each random access preamble occupies a bandwidth corresponding to six consecutive resource blocks. The starting frequency is specified by the network. That is, the transmission of the random access preamble is restricted to certain time and frequency resources. There is no frequency hopping for the PRACH. The PRACH attempt is carried in a single subframe (1 ms) or in a sequence of few contiguous subframes and a UE can make only a single PRACH attempt per frame (10 ms).

[0041] FIG. 5 is a diagram 500 illustrating an example of a radio protocol architecture for the user and control planes in LTE. The radio protocol architecture for the UE and the eNB is shown with three layers: Layer 1, Layer 2, and Layer 3. Layer 1 (LI layer) is the lowest layer and implements various physical layer signal processing functions. The LI layer will be referred to herein as the physical layer 506. Layer 2 (L2 layer) 508 is above the physical layer 506 and is responsible for the link between the UE and eNB over the physical layer 506.

[0042] In the user plane, the L2 layer 508 includes a media access control (MAC) sublayer 510, a radio link control (RLC) sublayer 512, and a packet data convergence protocol (PDCP) 514 sublayer, which are terminated at the eNB on the network side. Although not shown, the UE may have several upper layers above the L2 layer 508 including a network layer (e.g., IP layer) that is terminated at the PDN gateway 118 on the network side, and an application layer that is terminated at the other end of the connection (e.g., far end UE, server, etc.).

[0043] The PDCP sublayer 514 provides multiplexing between different radio bearers and logical channels. The PDCP sublayer 514 also provides header compression for upper layer data packets to reduce radio transmission overhead, security by ciphering the data packets, and handover support for UEs between eNBs. The RLC sublayer 512 provides segmentation and reassembly of upper layer data packets, retransmission of lost data packets, and reordering of data packets to compensate for out-of-order reception due to hybrid automatic repeat request (HARQ). The MAC sublayer 510 provides multiplexing between logical and transport channels. The MAC sublayer 510 is also responsible for allocating the various radio resources (e.g., resource blocks) in one cell among the UEs. The MAC sublayer 510 is also responsible for HARQ operations.

[0044] In the control plane, the radio protocol architecture for the UE and eNB is substantially the same for the physical layer 506 and the L2 layer 508 with the exception that there is no header compression function for the control plane. The control plane also includes a radio resource control (RRC) sublayer 516 in Layer 3 (L3 layer). The RRC sublayer 516 is responsible for obtaining radio resources (i.e., radio bearers) and for configuring the lower layers using RRC signaling between the eNB and the UE.

[0045] FIG. 6 is a block diagram of an eNB 610 in communication with a UE 650 in an access network. In the DL, upper layer packets from the core network are provided to a controller/processor 675. The controller/processor 675 implements the functionality of the L2 layer. In the DL, the controller/processor 675 provides header compression, ciphering, packet segmentation and reordering, multiplexing between logical and transport channels, and radio resource allocations to the UE 650 based on various priority metrics. The controller/processor 675 is also responsible for HARQ operations, retransmission of lost packets, and signaling to the UE 650.

[0046] The transmit (TX) processor 616 implements various signal processing functions for the LI layer (i.e., physical layer). The signal processing functions includes coding and interleaving to facilitate forward error correction (FEC) at the UE 650 and mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-phase- shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols are then split into parallel streams. Each stream is then mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time and/or frequency domain, and then combined together using an Inverse Fast Fourier Transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator 674 may be used to determine the coding and modulation scheme, as well as for spatial processing. The channel estimate may be derived from a reference signal and/or channel condition feedback transmitted by the UE 650. Each spatial stream is then provided to a different antenna 620 via a separate transmitter 618TX. Each transmitter 618TX modulates an RF carrier with a respective spatial stream for transmission.

[0047] At the UE 650, each receiver 654RX receives a signal through its respective antenna 652. Each receiver 654RX recovers information modulated onto an RF carrier and provides the information to the receive (RX) processor 656. The RX processor 656 implements various signal processing functions of the LI layer. The RX processor 656 performs spatial processing on the information to recover any spatial streams destined for the UE 650. If multiple spatial streams are destined for the UE 650, they may be combined by the RX processor 656 into a single OFDM symbol stream. The RX processor 656 then converts the OFDM symbol stream from the time-domain to the frequency domain using a Fast Fourier Transform (FFT). The frequency domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, and the reference signal, is recovered and demodulated by determining the most likely signal constellation points transmitted by the eNB 610. These soft decisions may be based on channel estimates computed by the channel estimator 658. The soft decisions are then decoded and deinterleaved to recover the data and control signals that were originally transmitted by the eNB 610 on the physical channel. The data and control signals are then provided to the controller/processor 659.

[0048] The controller/processor 659 implements the L2 layer. The controller/processor can be associated with a memory 660 that stores program codes and data. The memory 660 may be referred to as a computer-readable medium. In the UL, the controller/processor 659 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover upper layer packets from the core network. The upper layer packets are then provided to a data sink 662, which represents all the protocol layers above the L2 layer. Various control signals may also be provided to the data sink 662 for L3 processing. The controller/processor 659 is also responsible for error detection using an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support HARQ operations.

In the UL, a data source 667 is used to provide upper layer packets to the controller/processor 659. The data source 667 represents all protocol layers above the L2 layer. Similar to the functionality described in connection with the DL transmission by the eNB 610, the controller/processor 659 implements the L2 layer for the user plane and the control plane by providing header compression, ciphering, packet segmentation and reordering, and multiplexing between logical and transport channels based on radio resource allocations by the eNB 610. The controller/processor 659 is also responsible for HARQ operations, retransmission of lost packets, and signaling to the eNB 610.

Channel estimates derived by a channel estimator 658 from a reference signal or feedback transmitted by the eNB 610 may be used by the TX processor 668 to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor 668 are provided to different antenna 652 via separate transmitters 654TX. Each transmitter 654TX modulates an RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the eNB 610 in a manner similar to that described in connection with the receiver function at the UE 650. Each receiver 618RX receives a signal through its respective antenna 620. Each receiver 618RX recovers information modulated onto an RF carrier and provides the information to a RX processor 670. The RX processor 670 may implement the LI layer.

The controller/processor 675 implements the L2 layer. The controller/processor 675 can be associated with a memory 676 that stores program codes and data. The memory 676 may be referred to as a computer-readable medium. In the UL, the control/processor 675 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover upper layer packets from the UE 650. Upper layer packets from the controller/processor 675 may be provided to the core network. The controller/processor 675 is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.

[0053] FIG. 7 illustrates a wireless network system having different domains. A rSRVCC procedure may be used to facilitate handoff and/or handover of a call, such as a voice call, from a CS domain 740 to a PS domain 720. A voice call in PS domain 720 may employ voice over Internet Protocol (VoIP), voice over LTE (VoLTE), or other services to transport voice calls through a PS network.

[0054] An rSRVCC procedure may be performed in a CS domain 740 (e.g.,

GSM/CDMA) by a mobile switching center (MSC) 746 responsible for routing voice calls and other services. The MSC 746 typically handles call setup and releases, mobility and hand-over requirements during the call and accounting (charging). During handover of a UE 702, an MSC 746 which anchors the CS call determines a target PS domain MME 724 and/or serving GPRS support node (SGSN) 744. For example, when MSC 746 determines that MME 724 is the target, the MSC 746 may provide MME 724 with PS domain context of the UE 702. In some embodiments, the target may be SGSN 744 which provides an interface between the radio system and the fixed network for PS services, and may perform functions needed to handle packet exchange with a UE 702. The SGSN 744 stores subscription and location information for each served UE 702, including the cell or the routing area (RA) in which the UE 702 is located.

[0055] To complete an rSRVCC procedure for handing off a UE 702 from CS service to a PS service, an MSC 746 provides the target MME 724 with information regarding registration context of the UE 702 in current PS domain 720, to enable the target MME 724 to initiate PS handover. PS domain registration context may indicate, for example, a packet temporary mobile subscriber identity (P-TMSI), a routing area identity (RAI), a P-TMSI Signature and a globally unique temporary identity (GUTI).

[0056] A P-TMSI identifies a UE 702 within a given RA on a temporary basis and is used by the network to page the specified UE 702. A P-TMSI Signature conveys proof that a P-TMSI returned by the UE 702 corresponds to a P-TMSI allocated by the SGSN. An RAI is used for paging and registration purposes and comprises a location area identity (LAI) and a routing area code (RAC). A GUTI is an unambiguous identification of the UE 702 that allows the identification of a MME and network. [0057] An rSRVCC-capable UE 702 may inform the MSC 746 of its current PS domain registration context at call origination, during the call when PS registration context changes, during PS to CS SRVCC when a RA update (RAU) is not immediately performed. An rSRVCC procedure may be used when a CS call is initiated in a non-dual transfer mode (non-DTM) GERAN, in a network mode of operation (NM02) network, and/or as a result of a single radio voice call continuity (SRVCC). Accordingly, the only connection available to the UE 702 may be the CS signaling connection and/or the CS signaling connection may be the only reliable link between the UE 702 and the network at the time rSRVCC is desired. Moreover, the PS network may not be connected to the CS network. In some instances, the UE 702 may not yet have performed RAU after SRVCC.

[0058] Certain embodiments permit sharing of the PS context of UE 702 between an

MSC 746 and MME 724 such that PS domain registration information of UE 702 may be provided to a target PS domain MME 724 during handover. In some embodiments, the UE 702 provides PS context information to the MSC 746. In some embodiments, a target MME 724 determines this information from a home subscriber server (HSS), which maintains subscription-related information. A target MME/SSGN typically needs to know the current PS registration context of a UE 702 during an rSRVCC.

[0059] Certain embodiments communicate PS domain context through one or more CS domain procedures. Mobility management (MM) common procedures may be used to convey PS domain information. MM common procedures may include temporary mobile subscriber identity (TMSI) reallocation, authentication and identification procedures. MM common procedures may also include international mobile subscriber identity (IMSI) detach and MM information procedures. MM common procedures may be initiated at any time and, with the exception of IMSI detach, MM common procedures are initiated by the network.

[0060] Certain MM-specific procedures may be used to convey PS domain information.

MM-specific procedures may include location update procedures and IMSI attach procedures. Typically, MM-specific procedures are initiated when an MM connection is not yet established. PS domain information may be conveyed using one or more configuration management (CM) procedures including, for example, using one or more of a CM service request and CM reestablish request. A CM procedure can be initiated at any time but, typically, CM procedures do not inherently facilitate any information exchange. In some embodiments, an upper layer protocol is used for information exchange when a CM procedure is invoked.

PS domain information may be conveyed using one or more call control signaling procedures that may be used for call setup and call progress related functions. Call control signaling procedures may be initiated anytime.

In one example, an MM identification procedure may be used and/or extended to permit reporting of PS domain information. An MSC 746 configured to support rSRVCC may query a UE 702, requesting one or more of a PTMSI, an RAI, and a PTMSI signature when rSRVCC is needed. When the UE 702 is configured to support rSRVCC, the UE 702 may provide current information on its PS domain registration status. The MSC 746 may then provide the current information to a target MME 724. FIG. 8 includes a table 800 that illustrates the content of an identity request message. Table 802 illustrates a simplified example of encoding that identifies the type of identity to be provided.

In another example, an MSC 746 may provide a target MME 724 with an IMSI of UE 702. The target MME 724 may query an HSS associated with the UE 702, requesting the current identifier of the MME 724 associated with the UE 702. Upon receiving this information from the HSS, the target MME 724 may contact the current MME 724 and provide the current MME 724 the IMSI of the UE 702. The current SGSN/MME may then determine the current PS registration context of the UE 702. Thereafter, the current SGSN/MME and the target SGSN/MME may perform a PS handover.

FIG. 9 depicts am detailed example of mobile identity information element content, including different information element types 902, 906, and 908.

The purpose of the Mobile Identity information element is to provide an identity that may comprise the IMSI), TMSI, P-TMSI, M-TMSI, the international mobile equipment identity (IMEI), the IMEI with the software version number (IMEISV), and/or the temporary mobile group identity (TMGI) associated with the optional Multimedia Broadcast/Multicast Service (MBMS) session Identity.

The network and/or UE may select a mobile identity type based on application, priorities, preferences and other factors. In the example of packet paging, the network may select the mobile identity type based on a priority system where P- TMSI is used if available and IMSI is used otherwise. In the example of MBMS (pre-)notification the network may select a mobile identity type 906 referred to as "TMGI and optional MB MS Session Identity". Identity type 906 is typically used in MBMS (pre-) notification procedures.

In some embodiments, UE and the network may select the mobile identity type based on priority where TMSI is used if available, and IMSI is used otherwise.

In the example of mobile terminated call establishment the UE may select the same mobile identity type as received from the network in a paging request message. In some instances, (e.g. dual transfer mode CS), the UE may select the mobile identity type according to a predefined or preconfigured priority scheme where TMSI is used if available, and IMSI is used otherwise.

In the example where a paging response message is sent as a response to a paging for CS fallback, the UE may: (i) select the TMSI as mobile identity type if the network has, in E-UTRAN, paged the MS for CS fallback using the S-TMSI, or indicated TMSI in the a CS service notification message; (ii) select the IMSI as mobile identity type if the network has, in E-UTRAN, paged the MS for CS fallback using the IMSI, or indicated IMSI in the CS service notification message.

In the example of emergency call establishment and re-establishment the UE may select the mobile identity type according to a predefined or preconfigured priority system whereby (i) the TMSI is used if available and if the location update status is UPDATED, and the stored location area identity (LAI) is equal to the one received on the BCCH from the current serving cell; (ii) IMSI is used in cases where no TMSI is available or TMSI is available but either the update status is different from UPDATED, or the stored LAI is different from the one received on the BCCH from the current serving cell; and (iii) the IMEI is used in cases where no SIM/USIM is available or the SEVI/USIM is considered as not valid by the UE or no IMSI or TMSI is available. In the example of an identification procedure (e.g. GPRS mobility management (GMM) identification procedure) the UE may select the mobile identity type which was requested by the network, if available. If the requested identity is not available, then the mobile station may indicate an identity type "No Identity." In the example of ciphering mode setting procedure and in GMM authentication and ciphering procedure the mobile may select the IMEISV.

A typical mobile identity information element 904, 906, and 908 is coded to provide different types of information. A type of identity may be encoded as illustrated in the Type filed extracted as table 902. An odd/even indication may determine whether an even or odd number of identity digits is provided. The odd/even indication may also be used to determine when the TMSI/P-TMSI or TMGI and MBMS Session Identity is used.

Identity digits for the IMSI, IMEI and IMEISV may be encoded using BCD coding, binary, hexadecimal, or other suitable coding scheme. In some embodiments unused digits may be filled with a padding value, such as an end mark coded as "1111.". When a the identity type is "No Identity," the identity digit bits may be encoded with all 0's, all l's or any suitable combination of digits and bits, and the length of the mobile identity contents parameter may be set to a value that conveys additional information. In one example, the mobile identity contents parameter may have a value of "1" when the identification procedure is used, "2" if the GMM identification procedure is used, and "3" if the EMM identification procedure is used.

Certain codes may be provided by each administration. In the example where the mobile identity comprises a TMSI/P-TMSI/M-TMSI then certain bits may coded as "1111" or other predetermined value and the coding of the TMSI/P-TMSI may be left open for each administration.

Other information may include a mobile country code (MCC), a mobile network code (MNC), an indication of presence or absence of MCC/MNC, MBMS session identity, and MBMS Session identity indication (whether MBMS session identity is present), and an MBMS Service ID. The contents of the MBMS Service ID field may be coded as part of a temporary mobile group identity. The coding of the MBMS service ID is typically the responsibility of each administration and coding using full hexadecimal representation may be used. Other information may determine whether P-TMSI is native or mapped.

FIG. 10 includes a flow chart 1000 of a method of wireless communication. The method may be performed by a network entity such as MSC 746. At step 1002, the MSC 746 request PS registration information from a UE 702 while UE 702 is associated with a CS network. The PS registration information may be requested from the UE 702 if the UE 702 is determined to be capable of performing the rSRVCC procedure. Otherwise, the procedure may be terminated. The CS network may comprise a GSM network.

In some embodiments, requesting the PS registration information from UE 702 includes performing one or more MM procedures. The one or more MM procedures may comprise TMSI reallocation, TMSI authentication, and/or TMSI identification. The one or more MM procedures may comprise IMSI attach, and/or an IMSI detach.

In some embodiments, requesting the PS registration information from UE 702 includes performing a call management (CM) procedure. The CM procedure may comprise one or more of one or more of a CM service request and a CM reestablish request. Performing the CM procedure may include exchanging the PS registration information through an upper layer protocol.

In some embodiments, requesting the PS registration information from the UE 702 includes requesting the registration information using one or more call control signaling procedures.

At step 1004, the MSC 746 receives an identifier from the UE 702 in response to the request. The identifier may comprise one or more of a P-TMSI, an RAI, a P- TMSI signature, and a GUTI.

At step 1006, the MSC 746 performs an rSRVCC procedure using the identifier. In some embodiments, the rSRVCC procedure is performed when the identifier is provided to a target MME 724. In some embodiments, the rSRVCC procedure is performed when the identifier is provided to a target SGSN 744.

FIG. 10 includes a flow chart 1050 of a method of wireless communication. The method may be performed by a network entity such as MME 724. At step 1052, the MME 724 receives a request at a network entity of a PS network to initiate an rSRVCC procedure. The request may identify a UE 702 associated with a CS network. The CS network may comprise a GSM network.

At step 1054, the MME 724 queries an HSS 728 for PS registration information of the UE 702. The PS registration information may comprise one or more of a P- TMSI, an RAI, a P-TMSI signature, and a GUTI. In some embodiments, the PS registration information may be requested only when the UE 702 is determined to be capable of performing the rSRVCC procedure.

In some embodiments, the HSS 728 is queried determining an identifier of a PS domain network identity associated with the UE 702, and querying the PS network entity for PS domain registration information of the UE 702.

At step 1056, the MME 724 performs the rSRVCC procedure using the PS registration information of the UE 702.

FIG. 11 is a conceptual data flow diagram 1100 illustrating the data flow between different modules/means/components in an exemplary apparatus 1102. The apparatus may be a network entity such as an MME 724 or MSC 746. The apparatus includes a receiving module 1104 that processes queries and responses to queries, an identifying module 1106 that identifies registration information for UE 702, an rSRVCC module 1108 that processes handover of UE 702, and a transmission module 1110 that prepares and sends messages.

[0086] The apparatus may include additional modules that perform each of the steps of the algorithm in the aforementioned flow charts of FIG. 10. As such, each step in the aforementioned flow charts of FIG. 10 may be performed by a module and the apparatus may include one or more of those modules. The modules may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by a processor configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

[0087] FIG. 12 is a diagram 1200 illustrating an example of a hardware implementation for an apparatus 1102' employing a processing system 1214. The processing system 1214 may be implemented with a bus architecture, represented generally by the bus 1224. The bus 1224 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 1214 and the overall design constraints. The bus 1224 links together various circuits including one or more processors and/or hardware modules, represented by the processor 1204, the modules 1104, 1106, 1108, 1110, and the computer-readable medium 1206. The bus 1224 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

[0088] The processing system 1214 may be coupled to a transceiver 1210. The transceiver 1210 is coupled to one or more antennas 1220. The transceiver 1210 provides a means for communicating with various other apparatus over a transmission medium. The processing system 1214 includes a processor 1204 coupled to a computer-readable medium 1206. The processor 1204 is responsible for general processing, including the execution of software stored on the computer- readable medium 1206. The software, when executed by the processor 1204, causes the processing system 1214 to perform the various functions described supra for any particular apparatus. The computer-readable medium 1206 may also be used for storing data that is manipulated by the processor 1204 when executing software. The processing system further includes at least one of the 1104, 1106, 1108, and 1110. The modules may be software modules running in the processor 1204, resident/stored in the computer readable medium 1206, one or more hardware modules coupled to the processor 1204, or some combination thereof. The processing system 1214 may be a component of the eNB 610 and may include the memory 676 and/or at least one of the TX processor 616, the RX processor 670, and the controller/processor 675

In one configuration, the apparatus 1102/1102' for wireless communication includes means 1106 for requesting PS registration information from a UE 702 while the UE 702 is associated with a CS network, means 1104 for receiving an identifier from the UE 702 in response to the request, and means 1108 for performing an rSRVCC procedure using the identifier.

In another configuration, the apparatus 1102/1102' for wireless communication includes means 1104 for receiving a request to initiate an rSRVCC procedure, means 1106 for querying an HSS 728 for PS registration information of a UE 702, and means 1108 for performing the rSRVCC procedure using the PS registration information of the UE 702.

The aforementioned means may be one or more of the aforementioned modules of the apparatus 1102 and/or the processing system 1214 of the apparatus 1102' configured to perform the functions recited by the aforementioned means. As described supra, the processing system 1214 may include the TX Processor 616, the RX Processor 670, and the controller/processor 675. As such, in one configuration, the aforementioned means may be the TX Processor 616, the RX Processor 670, and the controller/processor 675 configured to perform the functions recited by the aforementioned means.

Further disclosure is included in the Appendix.

It is understood that the specific order or hierarchy of steps in the processes disclosed is an illustration of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged. Further, some steps may be combined or omitted. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean "one and only one" unless specifically so stated, but rather "one or more." Unless specifically stated otherwise, the term "some" refers to one or more. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed as a means plus function unless the element is expressly recited using the phrase "means for."

WHAT IS CLAIMED IS:

Claims

1. A method of wireless communication, comprising:

requesting packet switched (PS) registration information from a user equipment (UE) while the UE is associated with a circuit switched (CS) network;

receiving an identifier from the UE in response to the request; and

performing a reverse single radio voice call continuity (rSRVCC) procedure using the identifier.

2. The method of claim 1, wherein the identifier comprises one or more of a packet temporary mobile subscriber identity (P-TMSI), a routing area identity (RAI), a P-TMSI signature, and a globally unique temporary identity (GUTI).

3. The method of claim 1, wherein the CS network comprises a global system for mobile communications (GSM) network.

4. The method of claim 1, wherein the PS registration information is requested from the UE when the UE is determined to be capable of performing the rSRVCC procedure.

5. The method of claim 1, wherein requesting the PS registration information from the UE includes performing a mobility management (MM) procedure.

6. The method of claim 5, wherein the MM procedure comprises one or more of a temporary mobile subscriber identity (TMSI) reallocation, authentication and identification.

7. The method of claim 5, wherein the MM procedure comprises one or more of an international mobile subscriber identity (IMSI) attach and an IMSI detach.

8. The method of claim 1, wherein requesting the PS registration information from the UE includes performing a call management (CM) procedure.

9. The method of claim 8, wherein the CM procedure comprises one or more of one or more of a CM service request and a CM reestablish request.

10. The method of claim 8, wherein performing the CM procedure comprises exchanging the PS registration information through an upper layer protocol.

11. The method of claim 1, wherein requesting the PS registration information from the UE includes requesting the registration information using one or more call control signaling procedures.

12. The method of claim 1, further comprising providing the identifier to a target mobile management entity (MME).

13. The method of claim 1, further comprising providing the identifier to a target serving GPRS support node (SGSN).

14. An apparatus for wireless communication, comprising:

means for requesting packet switched (PS) registration information from a user equipment (UE) while the UE is associated with a circuit switched (CS) network;

means for receiving an identifier from the UE in response to the request; and means for performing a reverse single radio voice call continuity (rSRVCC) procedure using the identifier.

15. The apparatus of claim 14, wherein the identifier comprises one or more of a packet temporary mobile subscriber identity (P-TMSI), a routing area identity (RAI), a P-TMSI signature, and a globally unique temporary identity (GUTI).

16. The apparatus of claim 14, wherein the CS network comprises a global system for mobile communications (GSM) network.

17. The apparatus of claim 14, wherein the PS registration information is requested from the UE when the UE is determined to be capable of performing the rSRVCC procedure.

18. The apparatus of claim 14, wherein the means for requesting the PS registration information from the UE performs a mobility management (MM) procedure.

19. The apparatus of claim 18, wherein the MM procedure comprises one or more of a temporary mobile subscriber identity (TMSI) reallocation, authentication and identification.

20. The apparatus of claim 18, wherein the MM procedure comprises one or more of an international mobile subscriber identity (IMSI) attach and an IMSI detach.

21. The apparatus of claim 14, wherein the means for requesting the PS registration information from the UE performs a call management (CM) procedure.

22. The apparatus of claim 21, wherein the CM procedure comprises one or more of one or more of a CM service request and a CM reestablish request.

23. The apparatus of claim 21, wherein the means for performing the CM procedure exchanges the PS registration information through an upper layer protocol.

24. The apparatus of claim 14, wherein the means for requesting the PS registration information from the UE requests the registration information using one or more call control signaling procedures.

25. The apparatus of claim 14, wherein the means for performing a rSRVCC procedure provides the identifier to a target mobile management entity (MME).

26. The apparatus of claim 14, wherein the means for performing a rSRVCC procedure provides the identifier to a target serving GPRS support node (SGSN).

27. An apparatus for wireless communication, comprising:

a processing system configured to:

request packet switched (PS) registration information from a user equipment (UE) while the UE is associated with a circuit switched (CS) network; receive an identifier from the UE in response to the request; and perform a reverse single radio voice call continuity (rSRVCC) procedure using the identifier.

28. A computer program product, comprising:

a computer-readable medium comprising code for:

receiving an identifier from the UE in response to the request; and performing a reverse single radio voice call continuity (rSRVCC) procedure using the identifier.

29. A method of wireless communication, comprising:

receiving a request at a network entity of a packet switched (PS) network to initiate a reverse single radio voice call continuity (rSRVCC) procedure, wherein the request identifies a user equipment associated with a circuit switched (CS) network; querying a home subscriber server (HSS) for PS registration information of the UE; and

performing the rSRVCC procedure using the PS registration information of the

UE.

30. The method of claim 29, wherein the PS registration information comprises one or more of a packet temporary mobile subscriber identity (P-TMSI), a routing area identity (RAI), a P-TMSI signature, and a globally unique temporary identity (GUTI).

31. The method of claim 29, wherein the CS network comprises a global system for mobile communications (GSM) network.

32. The method of claim 29, wherein the PS registration information is requested from the HSS when the UE is determined to be capable of performing the rSRVCC procedure.

33. The method of claim 29, wherein querying the HSS includes:

determining an identifier of a PS domain network identity associated with the UE; and

querying the PS network entity for PS domain registration information of the UE.

34. An apparatus for wireless communication, comprising:

means for receiving a request at a network entity of a packet switched (PS) network to initiate a reverse single radio voice call continuity (rSRVCC) procedure, wherein the request identifies a user equipment (UE) associated with a circuit switched (CS) network;

means for querying a home subscriber server (HSS) for PS registration information of the UE; and

means for performing the rSRVCC procedure using the PS registration information of the UE.

35. The apparatus of claim 34, wherein the PS registration information comprises one or more of a packet temporary mobile subscriber identity (P-TMSI), a routing area identity (RAI), a P-TMSI signature, and a globally unique temporary identity (GUTI).

36. The apparatus of claim 34, wherein the CS network comprises a global system for mobile communications (GSM) network.

37. The apparatus of claim 34, wherein the PS registration information is requested from the UE when the UE is determined to be capable of performing the rSRVCC procedure.

38. The apparatus of claim 34, wherein the means for querying the HSS determines an identifier of a PS domain network identity associated with the UE, and queries the PS network entity for PS domain registration information of the UE.

39. An apparatus for wireless communication, comprising:

a processing system configured to:

receive a request at a network entity of a packet switched (PS) network to initiate a reverse single radio voice call continuity (rSRVCC) procedure, wherein the request identifies a user equipment (UE) associated with a circuit switched (CS) network;

query a home subscriber server (HSS) for PS registration information of the UE; and

perform the rSRVCC procedure using the PS registration information of the UE.

A computer program product, comprising:

a computer-readable medium comprising code for:

receiving a request at a network entity of a packet switched (PS) network to initiate a reverse single radio voice call continuity (rSRVCC) procedure, wherein the request identifies a user equipment (UE) associated with a circuit switched (CS) network;

querying a home subscriber server (HSS) for PS registration information of the UE; and

performing the rSRVCC procedure using the PS registration information of the UE.