KR20120014702A - Method for receiving call at dual mode device and apparatus therefor - Google Patents

Abstract

PURPOSE: A dual mode terminal call receiving method and a device thereof are provided to enhance a call setup delay when a fallback mode to a legacy network while receiving LTE data service in a dual mode terminal. CONSTITUTION: A terminal receives a paging request message for a circuit switching call from a legacy network through a MSC(Mobile Switching Center)(901,903). The terminal transmits an extended service request message to LTE network(904). The terminal converts the access network from the LTE to the legacy network(909). The terminal transmits a paging response message to the legacy network(913).

Description

TECHNICAL FOR RECEIVING CALL AT DUAL MODE DEVICE AND APPARATUS THEREFOR}

The present invention relates to a dual mode terminal. More specifically, the present invention relates to a call reception method and a device therefor in a dual mode terminal.

In the field of wireless mobile communication, there has been a steady evolution in terms of not only voice calls but also high-speed data transmission and reception. At present, the fourth generation mobile communication technology, for example, LTE (Long Term Evolution) wireless communication system, is drawing attention. However, in the situation where the 4th generation communication network and the 3rd generation or the 2nd generation communication network commercially available are mixed, the mobile communication terminal or the mobile communication data card is not only the 4th generation mobile communication technology but also the 3G which is commercially available and widely used now. / 2G mobile communication technology must be included at the same time. Therefore, in order to simultaneously support the next generation of mobile communication technology and the previous generation of mobile communication technology, a mobile terminal or a data card type device (hereinafter, dual mode terminal) having a dual modem processor is required.

The dual mode terminal is equipped with two modems having different communication methods to support wireless communication using each of them, and is mainly used in a region where heterogeneous communication networks are mixed. As a representative example of a dual mode terminal, both the 4th generation wireless communication technique (Long Term Evolution) and the 2nd generation wireless communication technique Global System for Mobile communications (GSM) or the 3rd generation wireless communication technique UMTS (Universal Mobile Telecommunications System) Available devices are attracting attention. In the present invention, a multi-mode device capable of communicating with both an LTE network and a GSM / UMTS network will be described. However, other types of wireless communication may also be applied to those skilled in the art. It is self-evident.

An object of the present invention is to provide a call reception method and a device therefor in a dual mode terminal.

Technical problems to be achieved in the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned above will be clearly understood by those skilled in the art from the following description. Could be.

In a wireless communication system according to an aspect of the present invention, a method for receiving a call by a terminal includes: receiving a MSC from a legacy communication network for a paging request message from a legacy communication network while receiving a data packet service from a long term evolution (LTE) network; receiving through a mobile switching center; Transmitting an extended service request message to the LTE network and releasing an established RRC connection with the LTE network; Changing an access network from the LTE communication network to the legacy communication network; Transmitting a paging response message to the legacy communication network; And receiving a call from the legacy communication network. The legacy communication network may be one of a Global System for Mobile communications (GSM) network and a Universal Mobile Telecommunications System (UMTS) communication network.

Furthermore, the step of releasing the RRC connection is characterized in that the terminal triggers the RRC connection release procedure.

Preferably, after the mobile switching center (MSC) receives a paging request message from the legacy communication network, the mobile switching center executes a first timer of a preset period, and when the first timer expires, LTE data from a serving gateway. Discontinue service.

More preferably, after the step of releasing the RRC connection, executing a second timer of a predetermined period; And when the second timer expires, transmitting a paging response to the legacy communication network.

On the other hand, a terminal device according to another aspect of the present invention, a wireless communication unit for transmitting and receiving signals from a Long Term Evolution (LTE) communication network and a legacy communication network; A first processor for processing a signal received from the LTE communication network; And a second processor for processing a signal received from the legacy network, wherein the first processor receives a paging request message for a circuit switching call from a legacy network while receiving a data packet service from the LTE network. receiving through a switching center, transmitting an extended service request message to the LTE network, releasing an established Radio Resource Control (RRC) connection with the LTE network, and the second processor Change the access network to the legacy communication network, transmit a paging response message to the legacy communication network, and receive a call from the legacy communication network. The legacy communication network may be one of a Global System for Mobile communications (GSM) network and a Universal Mobile Telecommunications System (UMTS) communication network.

Further, the first processor is characterized in that to trigger the RRC connection release procedure, to release the RRC connection.

Preferably, the mobile switching center (MSC), after receiving a paging request message from the legacy communication network, executes a first timer of a preset period, and when the first timer expires, LTE data from a serving gateway. Discontinue service.

More preferably, after executing the step of releasing the RRC connection, the first processor executes a second timer of a preset period and transmits a paging response to the legacy communication network when the second timer expires. It features.

According to embodiments of the present invention, a call setup delay that may occur when a fallback mode occurs to a legacy network while receiving an LTE data service from a dual mode terminal may be alleviated, thereby avoiding a circuit call drop.

The effects obtainable in the present invention are not limited to the above-mentioned effects, and other effects not mentioned above may be clearly understood by those skilled in the art from the following description. will be.

1 is a diagram conceptually illustrating a network structure of an E-UMTS.
2 is a diagram conceptually illustrating a network structure of an Evolved Universal Terrestrial Radio Access Network (E-UTRAN).
3 and 4 illustrate a control plane and a user plane (U-Plane, User-Plane) structure of a radio interface protocol between a terminal and an E-UTRAN based on the 3GPP radio access network standard. It is a figure which shows.
5 is a diagram showing the structure of a dual-mode terminal of the present invention.
6 is a conceptual diagram illustrating a structure of a dual mode terminal of the present invention.
FIG. 7 illustrates a situation in which a dual mode terminal receives a call from a legacy network while receiving a data service from an LTE network.
8 is a signal flow diagram illustrating a conventional procedure when a dual mode terminal receives a call from a legacy network while receiving a data service from an LTE network.
9 is a signal flow diagram illustrating a procedure according to an embodiment of the present invention when a dual mode terminal receives a call from a legacy network while receiving a data service from an LTE network.
10 illustrates a block diagram of a terminal device according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following detailed description, together with the accompanying drawings, is intended to illustrate exemplary embodiments of the invention and is not intended to represent the only embodiments in which the invention may be practiced. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, one of ordinary skill in the art appreciates that the present invention may be practiced without these specific details. For example, the following detailed description will be described in detail assuming that the main mobile communication system is a 3GPP LTE system, but is applicable to any other mobile communication system except for the specific matters of 3GPP LTE.

In some instances, well-known structures and devices may be omitted or shown in block diagram form centering on the core functions of the structures and devices in order to avoid obscuring the concepts of the present invention. In addition, the same components will be described with the same reference numerals throughout the present specification.

In the following description, it is assumed that the UE collectively refers to a mobile stationary or stationary user equipment such as a UE (User Equipment) and an MS (Mobile Station). It is also assumed that the base station collectively refers to any node of a network end that communicates with a terminal such as a Node B, an eNode B, and a base station.

Prior to describing the present invention, the following describes the Evolved Universal Mobile Telecommunications System (E-UMTS) and technical features related thereto.

1 is a diagram conceptually illustrating a network structure of an E-UMTS. In particular, the E-UMTS system has evolved from the existing WCDMA UMTS system and is currently undergoing basic standardization work in the 3rd Generation Partnership Project (3GPP). E-UMTS is also called a Long Term Evolution (LTE) system. For details of the technical specifications of UMTS and E-UMTS, refer to Release 7 and Release 8 of "3rd Generation Partnership Project (Technical Specification Group Radio Access Network)" respectively.

Referring to FIG. 1, an E-UMTS is mainly an Access Gateway (hereinafter referred to as an AG) connected to an external network by being located at an end of a user equipment (UE), a cell (eNB), and a network (E-UTRAN). It is composed. Typically, an eNB may transmit multiple data streams simultaneously for broadcast service, multicast service and / or unicast service. An interface for transmitting user traffic or control traffic may be used between eNBs.

The AG may be divided into a part that handles user traffic and a part that handles control traffic. In this case, a new interface may be used to communicate with each other between the AG for processing new user traffic and the AG for controlling traffic. In addition, the AG manages mobility of the UE in units of a tracking area (TA), and the TA is configured of a plurality of cells. When the UE moves from one TA to another TA, it notifies the AG that the TA where it is located has changed.

CN (Core Network) may be configured as a network node for user registration of the AG and the UE. An interface for distinguishing between E-UTRAN and CN may be used.

2 is a diagram conceptually illustrating a network structure of an Evolved Universal Terrestrial Radio Access Network (E-UTRAN).

Referring to FIG. 2, the E-UTRAN system is an evolved system from the existing UTRAN system. The E-UTRAN consists of cells (eNodeBs), and the cells are connected through an X2 interface. The cell is connected to the terminal through the air interface, and is connected to the Evolved Packet Core (EPC) through the S1 interface.

The EPC includes a mobility management entity (MME), a serving-gateway (S-GW), and a packet data network-gateway (PDN-GW). The MME has information about the access information of the terminal or the capability of the terminal, and this information is mainly used for mobility management of the terminal. S-GW is a gateway having an E-UTRAN as an endpoint, and PDN-GW is a gateway having a PDN (Packet Data Network) as an endpoint.

3 and 4 illustrate a control plane and a user plane (U-Plane, User-Plane) structure of a radio interface protocol between a terminal and an E-UTRAN based on the 3GPP radio access network standard. It is a figure which shows. In particular, the air interface protocol consists of a physical layer, a data link layer, and a network layer vertically, and horizontally a user plane and control for transmitting data information. It is divided into a control plane for transmitting a signal.

In addition, the protocol layers of FIGS. 3 and 4 are based on the Open System Interconnection (OSI) reference model, which is widely known in communication systems. The lower three layers are L1 (first layer) and L2 (second layer). , L3 (third layer).

The control plane means a path through which control messages used by the terminal and the network to manage a call are transmitted. The user plane refers to a path through which data generated at an application layer, for example, voice data or Internet packet data, is transmitted. Hereinafter, each layer of the control plane and the user plane of the radio protocol will be described.

The physical layer, which is the first layer, provides an information transfer service to an upper layer by using a physical channel. The physical layer is connected to the upper Media Access Control (MAC) layer through a transport channel. Data moves between the MAC layer and the physical layer through the transport channel. Data moves between the physical layer between the transmitting side and the physical side of the receiving side. The physical channel is modulated by an orthogonal frequency division multiplexing (OFDM) scheme and utilizes time and frequency as radio resources.

The MAC layer of the second layer provides a service to a radio link control (RLC) layer, which is a higher layer, through a logical channel. The RLC layer of the second layer supports reliable data transmission. The functionality of the RLC layer may be implemented as a functional block inside the MAC. In this case, the RLC layer may not exist. The PDCP (Packet Data Convergence Protocol) layer of the second layer performs a header compression function to reduce unnecessary control information in order to efficiently transmit an IP packet such as IPv4 or IPv6 over a narrow bandwidth interface. .

The radio resource control (RRC) layer located at the bottom of the third layer is defined only in the control plane, and the configuration, re-configuration, and release of radio bearers (RBs) are performed. Responsible for control of logical channels, transport channels and physical channels in connection with. The radio bearer refers to a service provided by the second layer for data transmission between the terminal and the E-UTRAN. To this end, the RRC layer exchanges RRC messages between the terminal and the network.

In FIG. 3, the non-access stratum (NAS) layer above the RRC layer performs functions such as session management and mobility management. The NAS layer is present in a mobility management entity (MME) of a terminal and a network.

MME is a key control-node in LTE access networks. The MME is responsible for tracking and paging processes for the terminal in the idle state. The MME is also involved in the radio bearer activation / deactivation process and is responsible for selecting a Serving Gateway (SGW) for UEs during 'Initial Attach' or during intra-LTE handovers including core network relocation. Together. The MME is responsible for terminal authentication through interaction with a Home Subscriber Server (HSS). NAS signaling is terminated in the MME, the MME is responsible for generating a temporary identifier and assigning to the terminal. The MME checks whether the UE has a right to camp on a PLMN (Public Land Mobile Network) of the service provider. The MME is the endpoint for encryption / integrity protection for NAS signaling in the network and is responsible for security key management. MME provides control plane functionality for mobility between LTE and 2G / 3G access networks.

In the NAS layer, two states are defined for ESM (EPS Mobility Management) registered state (EMM-REGISTERED) and EMM unregistered state (EMM-UNREGISTERED) for the mobility management of the UE, and these two states are applied to the UE and the MME. The initial terminal is in an EMM unregistered state, and the terminal performs a process of registering with the corresponding network through an initial attach procedure to access the network. If the contact procedure is successfully performed, the UE and the MME are in the EMM registration state.

In the NAS layer, two types of EPS connection management (ECM_IDLE) and ECM_CONNECTED (ECM_CONNECTED) are defined to manage a signaling connection between the UE and the EPC. These two states are the UE and the MME. Applies to When the UE in the ECM idle state makes an RRC connection with the E-UTRAN, the UE is in the ECM connection state. The MME, which is in the ECM idle state, becomes an ECM connection state when it establishes an S1 connection with the E-UTRAN. When the terminal is in the ECM dormant state, the E-UTRAN does not have a context of the terminal. Accordingly, the UE in the ECM idle state performs a UE-based mobility related procedure such as a cell selection or cell reselection procedure without receiving a command from the network. On the other hand, when the terminal is in the ECM connection state, the mobility of the terminal is managed by the command of the network. In the ECM idle state, when the location of the terminal is different from the location known by the network, the terminal informs the network of the corresponding location of the terminal through a TA update (Tracking Area Update) procedure.

5 is a diagram showing the structure of a dual-mode terminal of the present invention.

Referring to FIG. 5, a dual mode terminal may include an LTE processor for processing a signal received from an application processor and an LTE network, and a legacy processor for processing a signal received from a legacy network. Here, the legacy network refers to a GSM network, a second generation communication network, or a UMTS network, a third generation communication network.

The application processor may be configured as a module in hardware within the dual mode terminal, or may be included in a PC and configured independently of the dual mode terminal. In addition, the application processor may include a connection manager (CM) for managing and controlling a connection state to a legacy network or an LTE network according to a network environment.

More specifically, the CM performs a switching role for transmitting and receiving data between an application and a modem (legacy processor or LTE processor) according to a network connection state. That is, when the dual mode terminal is connected to the legacy network, the application data is transmitted and received through the A interface so that the legacy processor and the application are connected. When the dual mode terminal is connected to the LTE network, the application data is transmitted to the LTE processor. Send and receive over the B interface so that the application is connected.

The host interface is located between the legacy processor and the LTE processor, and may be used for transmitting control signals and data signals between the processors.

6 is a conceptual diagram illustrating a structure of a dual mode terminal of the present invention.

Referring to FIG. 6, the dual mode terminal may include two antennas, and the two antennas may have a single RX / Single TX structure. That is, it cannot receive signals from LTE network and legacy network (2G GSM network or 3G UMTS network) at the same time, and can only receive signals from one network, and also transmit signal to only one network of LTE network and legacy network. Possible form.

FIG. 7 illustrates a situation in which a dual mode terminal receives a call from a legacy network while receiving a data service from an LTE network.

Referring to FIG. 7, it is assumed that the dual mode terminal having the single RX / Single TX structure is located in an area where both LTE service and legacy service are available, and receives a data service, for example, a streaming service from the LTE network. In this case, when the dual mode UE receives a circuit call from the legacy network, the dual mode terminal stops the LTE data service as a fallback method and goes through a call setup process with the legacy network. However, it is assumed that packet switching handover (PS HO) is not supported between the LTE network and the legacy network assumed in the present invention, 2G GSM network or 3G UMTS network.

In the existing CS (Circuit Switched call) fallback system disclosed in 3GPP TS 23.272, a terminal performs a paging request signal through a mobile switching center (MSC) and an MME of an LTE network, which serves as a bridge between an LTE network and a legacy network. Receive. Upon receiving the paging request signal, the UE transmits a signal to perform an CS fallback procedure to the LTE network.

In response, the LTE network commands an inter-RAT cell change order or triggers an RRC connection release procedure so that the UE releases the RRC connection. Accordingly, the UE stops transmitting LTE data from the associated PDN gateway and the serving gateway to the UE by informing the LTE network that the RRC connection has been released, and releases the UE context. The terminal transmits a paging response signal to the legacy network as soon as the network check for the RRC connection release ends.

8 is a signal flow diagram illustrating a conventional procedure when a dual mode terminal receives a call from a legacy network while receiving a data service from an LTE network. In particular, Figure 8 is characterized in that the antenna of the dual-mode terminal is the Single RX / Single TX structure.

Referring to FIG. 8, the dual mode terminal of the present invention cannot receive signals simultaneously in both networks because the antenna structure is Single Tx / Single Rx. Accordingly, while the terminal receives the data service, as in step 801, the MME of the LTE network receives a paging request signal from the MSC. The MME transmits the paging request signal to the terminal in the form of a circuit switching service indicator (CS service notification) message in step 802.

Subsequently, when the terminal determines to receive a call service from the legacy network, in step 803, it sends an extended service request message to the MME of the LTE network to notify the use of the legacy circuit network to the LTE network. Send. Upon receiving this, the MME transmits an S1 “S1-AP message with CS Fallback indicator”, which is a permission message meaning that it may change to GERAN / UTRAN to the base station (eNodeB) of LTE in step 804, and the base station (eNodeB) responds to this. Sends an “S1-AP response message” to the MME.

In addition, the eNodeB transmits a signaling connection release message to the UE in step 806 to trigger an RRC connection release procedure, and in step 807, transmits a “UE context release message” to the MME to release the UE context. You can request

Since the UE does not support packet switching handover as described above, the UE performs the RRC connection release procedure as described in the 3GPP 36.311 document while changing the network to GERAN / UTRAN. In this case, the UE context release procedure is performed between the UE, the base station, and the MME as shown in step 808. In step 809, the UE searches for a suitable cell of the legacy network and receives system information to perform a RAT change procedure.

Next, the UE connected to the legacy network sends a stop request message of the data service to the MME of the LTE network through the Radio Network Subsystem (RNS) and the Serving GPRS Support Node (SGSN) in steps 810 and 811 as described in the 3GPP 23.060 document. Send. Upon receiving this message, the MME requests the serving gateway and the PDN gateway to stop the LTE data service and update the corresponding radio bearer.In step 812, the serving gateway and the PDN gateway perform the interruption of the LTE data service and then wirelessly transmit to the MME. The bearer update response signal (Update Bearer) is transmitted.

Finally, when the UE completes the RRC disconnection procedure and confirms the interruption of the LTE data service, the UE transmits a paging response message to the MSC through the base station subsystem (RNS) / RNS in step 813. Perform circuit call setup to the UMTS network.

In summary, in the above-described method, after the base station transmits an RRC release command to the terminal, the RRC connection release procedure is performed in a form in which the terminal releases the RRC connection. That is, it can be regarded as an RRC connection release procedure based on network triggering. However, if the terminal is located at the cell-cell boundary or in a state of very high mobility, the case where such an RRC release command is not properly transmitted to the terminal cannot be excluded. In this case, since the base station must wait for a response from the terminal, that is, an ACK signal, it may take a very long time until the RRC connection release procedure is completed, and further, the terminal context release is completed. If this delay is severe, the time required for the terminal to transmit a paging response to the legacy network and set up a call becomes long. Therefore, if the call establishment time limit is exceeded, the probability of leading to the call drop is also increased.

In order to solve this problem, the present invention proposes that when a dual mode terminal receives a paging request from a legacy network, the terminal transmits a terminal triggering RRC connection release message to the base station and releases the RRC connection by itself. Furthermore, as soon as the MME receives the paging request message from the MSC, it is preferable to update the radio bearer by transmitting a data service stop request message to the serving gateway and the PDN gateway when the first timer expires. In addition, after the UE releases the RRC connection, it is preferable to proceed with the second timer, and immediately send a paging response to the legacy network when the second timer expires. Hereinafter, the above-described method will be described in more detail with reference to FIG. 9.

9 is a signal flow diagram illustrating a procedure according to an embodiment of the present invention when a dual mode terminal receives a call from a legacy network while receiving a data service from an LTE network.

Referring to FIG. 9, while the terminal receives the data service, as shown in step 901, the MME of the LTE network receives a paging request signal from the MSC. Upon receiving the paging request signal, the MME drives the first timer in step 902 and transmits the paging request signal to the terminal in the form of a circuit switching service indicator (CS service notification) message in step 903. The first timer is for updating the radio bearer by transmitting a data service stop request message to the serving gateway and the PDN gateway when the timer expires as described above.

Subsequently, when the UE determines to receive a call service from the legacy network, the UE sends an extended service request message to the base station (eNodeB) of the LTE network in step 904 to use the legacy circuit network for the LTE network. Send a notification of meaning and directly trigger the RRC disconnection procedure. In addition, the base station eNodeB forwards the extended service request message to the MME in step 905. In response to this, the MME and the eNodeB “S1-AP message”, which is a permission message meaning that the access network may be changed to a GSM EDGE Radio Access Network (GERAN) / UMTS Terrestrial Radio Access Network (UTRAN) at step 906 and a response thereto. In step 907, the "S1-AP response message" is transmitted and received through the S1 interface, and the terminal context is released according to the 3GPP TS 23.401 document.

Meanwhile, the terminal may directly drive the first timer after directly triggering the RRC connection release procedure, and may transmit a legacy paging response immediately when the timer expires. In step 909, the UE searches for a suitable cell of the legacy network, receives system information, and performs a RAT change procedure.

Separately, when the first timer expires, the MME requests the serving gateway and the PDN gateway to stop the LTE data service and update the radio bearer corresponding to the serving gateway and the PDN gateway at step 910 and step 911. After stopping the data service, a radio bearer update response signal (Update Bearer) is transmitted to the MME. Finally, when the second timer expires, the UE transmits a paging response message to the MSC through the BSS / RNS in step 913, and based on this, the MSC performs GSM / UMTS circuit call setup.

According to the above-described method, the terminal can proceed with the disconnection procedure immediately without waiting for the grant or ACK response for the RRC connection release from the network, the terminal itself paging response message without confirmation of data service interruption to the LTE network Because it can transmit to the legacy network, call setup delay due to message loss can be reduced and call drop rate can be reduced in the presence of high mobility such as inter-cell boundaries or high-speed trains where the wireless environment is unstable.

10 illustrates a block diagram of a terminal device according to an embodiment of the present invention.

Referring to FIG. 10, the terminal device 1000 includes a processor 1010, a memory 1020, an RF module 1030, a display module 1040, and a user interface module 1050. The terminal device 1000 is shown for convenience of description and some modules may be omitted. In addition, the terminal device 1000 may further include necessary modules. In addition, in the terminal device 1000, some modules may be classified into more granular modules. The processor 1020 may separately include an LTE processor for communicating with an LTE network and a legacy processor for communicating with a legacy network, and are configured to perform an operation according to the above-described embodiment of the present invention.

The memory 1020 is connected to the processor 1010 and stores an operating system, an application, program code, data, and the like. The RF module 1030 is connected to the processor 1010 and performs a function of converting a baseband signal into a radio signal or converting a radio signal into a baseband signal. To this end, the RF module 1030 performs analog conversion, amplification, filtering and frequency up-conversion, or a reverse process thereof. The display module 1040 is connected to the processor 1010 and displays various information. The display module 1040 may use well-known elements such as, but not limited to, a liquid crystal display (LCD), a light emitting diode (LED), and an organic light emitting diode (OLED). The user interface module 1050 is connected to the processor 1010 and may be configured with a combination of well-known user interfaces such as a keypad, a touch screen, and the like.

The embodiments described above are the components and features of the present invention are combined in a predetermined form. Each component or feature is to be considered optional unless stated otherwise. Each component or feature may be implemented in a form that is not combined with other components or features. It is also possible to combine some of the components and / or features to form an embodiment of the invention. The order of the operations described in the embodiments of the present invention may be changed. Some configurations or features of certain embodiments may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments. It is obvious that the claims may be combined to form an embodiment by combining claims that do not have an explicit citation relationship in the claims or as new claims by post-application correction.

In this document, the embodiments of the present invention have been mainly described with reference to the data transmission / reception relationship between the terminal and the base station. The specific operation described herein as being performed by the base station may be performed by its upper node, in some cases. That is, it is apparent that various operations performed for communication with a terminal in a network including a plurality of network nodes including a base station can be performed by a network node other than the base station or the base station. A base station may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), an access point, and the like. In addition, the terminal may be replaced with terms such as a user equipment (UE), a mobile station (MS), a mobile subscriber station (MSS), and the like.

Embodiments according to the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of a hardware implementation, an embodiment of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), FPGAs ( field programmable gate arrays), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of implementation by firmware or software, an embodiment of the present invention may be implemented in the form of a module, procedure, function, etc. that performs the functions or operations described above. The software code may be stored in a memory unit and driven by a processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various known means.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit of the invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit of the invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

Claims (10)

In the method of receiving a call (Call) in the terminal in a wireless communication system,
Receiving a paging request message for a circuit switching call from a legacy communication network through a mobile switching center (MSC) while receiving a data packet service from an LTE (Long Term Evolution) network;
Transmitting an extended service request message to the LTE network and releasing an established RRC connection with the LTE network;
Changing an access network from the LTE communication network to the legacy communication network;
Transmitting a paging response message to the legacy communication network; And
Receiving a call from the legacy communication network,
How to receive a call. The method of claim 1,
The mobile switching center (MSC),
After receiving a paging request message from the legacy communication network, executing a first timer of a preset period,
When the first timer expires, characterized in that to stop the LTE data service from the serving gateway,
How to receive a call. The method of claim 1,
Executing a second timer of a preset period after executing the step of releasing the RRC connection; And
Transmitting a paging response to the legacy communication network when the second timer expires,
How to receive a call. The method of claim 1,
The step of releasing the RRC connection,
Characterized in that the terminal triggers the RRC connection release procedure,
How to receive a call. The method of claim 1,
The legacy communication network,
Characterized in that it is one of a Global System for Mobile communications (GSM) network or a Universal Mobile Telecommunications System (UMTS) network,
How to receive a call. A wireless communication unit for transmitting and receiving signals from a Long Term Evolution (LTE) communication network and a legacy communication network;
A first processor for processing a signal received from the LTE communication network; And
A second processor for processing a signal received from the legacy communication network;
The first processor,
Receiving a paging request message for a circuit switching call from a legacy communication network through a mobile switching center (MSC) while receiving a data packet service from the LTE network, and transmitting an extended service request message to the LTE network. And, release the RRC (Radio Resource Control) connection established with the LTE communication network,
The second processor,
Change the access network from the LTE communication network to the legacy communication network, transmit a paging response message to the legacy communication network, and receive a call from the legacy communication network,
Terminal device. The method according to claim 6,
The mobile switching center (MSC),
After receiving a paging request message from the legacy communication network, executing a first timer of a preset period,
When the first timer expires, characterized in that to stop the LTE data service from the serving gateway,
Terminal device. The method according to claim 6,
The first processor,
After executing the step of releasing the RRC connection, executing a second timer of a preset period, and when the second timer expires, transmitting a paging response to the legacy communication network.
Terminal device. The method according to claim 6,
The first processor,
In order to release the RRC connection, characterized in that triggering the RRC connection release procedure,
Terminal device. The method according to claim 6,
The legacy communication network,
Characterized in that it is one of a Global System for Mobile communications (GSM) network or a Universal Mobile Telecommunications System (UMTS) network,
Terminal device.

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