KR101824994B1 - User equipment apparatus and method for performing handover between inter RATs - Google Patents

Abstract

A method for performing handover between heterogeneous networks and a terminal apparatus using the same. A terminal apparatus according to the present invention includes: a first type communication module configured to transmit and receive signals to and from a first type base station using a first wireless communication system; A second type communication module configured to transmit and receive a signal to and from a second type base station using a second wireless communication method; And a second communication module for communicating with the first type communication module, the first type communication module being operable to receive a signal requesting handover from a first type base station operating in an active state to a second type base station, state to the second type base station operating in the second type of base station. When the first type communication module receives from the first type base station a measurement request signal including list information for one or more second type base stations, the processor determines, based on the list information, Type base station, and the first type communication module can transmit the measured result by the processor to the first type base station.

Description

TECHNICAL FIELD [0001] The present invention relates to a method and apparatus for performing handover between heterogeneous networks,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to wireless communication, and more particularly, to a method for performing handover between heterogeneous networks and a terminal apparatus therefor.

Handover refers to a function in which a mobile station automatically tunes to a new communication channel of a neighboring base station and continuously maintains a communication state when a mobile station moves from a cell boundary to a neighboring base station service area. The call disconnection time during the automatic change of the call channel is about 15 ms or less. In such a short period of time, it is difficult for the subscriber in the call to perform the message communication between the base station and the terminal to hardly detect the momentary call disconnection state. Due to the development of wireless communication technology, the number of terminals is rapidly increasing and heterogeneous networks using different wireless communication methods are expanding. Heterogeneous network or media handover techniques have also been developed.

The handover method includes hard handover (HHO) and soft handover. Soft handover techniques include macro diversity handover (MDHO) and fast base station switching Switching, FBSS). However, since the soft handover technique has a problem of overhead, hard handover techniques are under study.

In the wireless mobile communication field, not only voice communication but also data transmission and reception have been steadily evolving. Currently, 4th generation mobile communication technology, for example, LTE (Long Term Evolution) wireless communication system is attracting attention. However, in the situation where the fourth generation communication network and the third generation communication network that have been commercialized are mixed, the mobile communication terminal or the mobile communication data card is not only used for the fourth generation mobile communication technology but also for the 3G mobile communication technology At the same time. Accordingly, a mobile terminal or a data card type device (hereinafter referred to as a dual mode terminal) having a dual modem processor is required to simultaneously support the next generation mobile communication technology and the existing generation mobile communication technology.

The dual mode terminal is equipped with two modems having different communication methods and supports wireless communication using each of them, and is mainly used in a region where heterogeneous communication networks are mixed. 2. Description of the Related Art As a typical example of a dual mode terminal, a device capable of using both LTE (Long Term Evolution) wireless communication and eHRPD (enhanced High-Rate Packet Data) wireless communication is attracting attention.

However, there is no research on the efficient handover scheme of a terminal currently operating in a dual mode,

SUMMARY OF THE INVENTION The present invention provides a method for performing handover between heterogeneous networks.

According to another aspect of the present invention, there is provided a terminal apparatus for performing handover between heterogeneous networks.

The technical problems to be solved by the present invention are not limited to the technical problems and other technical problems which are not mentioned can be understood by those skilled in the art from the following description.

According to another aspect of the present invention, there is provided a method for performing a handover between a heterogeneous network of a mobile station (MS) according to the present invention, including: performing handover from a first type BS operating in an active state to a second type BS; Receiving a signal requesting to do; And performing a handover to a second type base station operating in an idle state with the terminal of the second type base station based on the signal reception, wherein the first and second type base stations Different wireless communication methods. The method includes receiving a measurement request signal including list information for one or more second type base stations from the first type base station; Performing measurements on the one or more second type base stations based on the list information; And transmitting the measurement result to the first type base station.

According to another aspect of the present invention, there is provided a terminal apparatus for performing handover between heterogeneous networks, including: a first type communication module configured to transmit and receive signals to and from a first type base station using a first wireless communication method; A second type communication module configured to transmit and receive a signal to and from a second type base station using a second wireless communication method; And a second communication module for communicating with the first type communication module, the first type communication module being operable to receive a signal requesting handover from a first type base station operating in an active state to a second type base station, state to the second type base station operating in the second type of base station. Wherein when the first type communication module receives a measurement request signal including list information for one or more second type base stations from the first type base station, Type base station, and the first type communication module may transmit the measurement result by the processor to the first type base station.

 According to the handover between heterogeneous networks according to the present invention, an unnecessary band or frequency of a terminal is changed and a handover is performed, so that a handover time can be shortened and communication performance can be improved.

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

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
1 is a diagram conceptually showing a network structure of an E-UMTS.
2 is a conceptual diagram illustrating a network structure of an evolved universal terrestrial radio access network (E-UTRAN).
3 and 4 illustrate a control plane and a U-plane (User-Plane) structure of a radio interface protocol between a UE based on the 3GPP radio access network standard and the E-UTRAN Fig.
5 is a diagram illustrating a configuration of a terminal apparatus 500 for performing handover between heterogeneous networks according to the present invention.
6 is a diagram illustrating a configuration of a terminal apparatus 500 for performing handover between heterogeneous networks according to the present invention.
FIG. 7 is a flowchart illustrating a process of a handover between a heterogeneous network according to a preferred embodiment of the present invention.
8 is a flowchart illustrating a detailed procedure of a handover from an LTE base station to an eHRPD base station according to an exemplary embodiment of the present invention.

Hereinafter, preferred embodiments according to 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, those skilled in the art will appreciate that the present invention may be practiced without these specific details. For example, the following detailed description assumes that the mobile communication system is an Institute of Electrical and Electronics Engineers (IEEE) 802.16 system or a 3GPP (3rd Generation Partnership Project). However, the IEEE 802.16 system, The present invention is applicable to any other mobile communication system.

In some instances, well-known structures and devices may be omitted or may be shown in block diagram form, centering on the core functionality of each structure and device, to avoid obscuring the concepts of the present invention. In the following description, the same components are denoted by the same reference numerals throughout the 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), an MS (Mobile Station), and an AMS (Advanced Mobile Station). It is also assumed that the base station collectively refers to any node at a network end that communicates with a terminal such as a Node B, an eNode B, a BS (Base Station), and an AP (Access Point).

In a mobile communication system, a mobile station can receive information from a base station through a downlink, and the mobile station can also transmit information through an uplink. The information transmitted or received by the terminal includes data and various control information, and various physical channels exist depending on the type of information transmitted or received by the terminal.

Prior to describing the present invention, the Evolved Universal Mobile Telecommunications System (E-UMTS), which is a technical field to which the present invention is applied, and related technical features will be described below.

1 is a diagram conceptually showing 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 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 an Access Gateway (hereinafter referred to as AG) located at the end of a UE, a cell (eNB), and a network (E-UTRAN) . Typically, an eNB may simultaneously transmit multiple data streams for broadcast services, multicast services, and / or unicast services. An interface for transmitting user traffic or control traffic may be used between eNBs.

The AG may be divided into a part for handling user traffic and a part for processing control traffic. At this time, a new interface between the AG for processing new user traffic and the AG for processing control traffic can be communicated with each other. Also, the AG manages the mobility of the UE in a TA (Tracking Area) unit, and the TA is composed of a plurality of cells. If the terminal moves from one TA to another TA, it informs AG that the TA where it is located has changed.

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

2 is a conceptual diagram 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 in an existing UTRAN system. The E-UTRAN is composed of cells (eNBs), and the cells are connected via the X2 interface. The cell is connected to the terminal through the air interface, and is connected to the EPC (Evolved Packet Core) through the S1 interface.

EPC is composed of MME (Mobility Management Entity), S-GW (Serving-Gateway) and PDN-GW (Packet Data Network-Gateway). The MME has information on the access information of the terminal or the capability of the terminal, and this information is mainly used for managing the mobility of the terminal. The S-GW is a gateway having an E-UTRAN as an end point, and the PDN-GW is a gateway having a PDN (Packet Data Network) as an end point.

3 and 4 illustrate a control plane and a U-Plane (User-Plane) structure of a radio interface protocol between a UE and an E-UTRAN based on the 3GPP radio access network standard Fig.

In particular, the wireless interface protocol consists of a physical layer, a data link layer, and a network layer vertically, and horizontally includes a user plane for data information transmission and a control plane And a control plane for signal transmission.

The protocol layers of FIGS. 3 and 4 are based on an Open System Interconnection (OSI) reference model widely known in communication systems. The lower three layers are referred to as L1 (first layer), L2 (second layer) , And L3 (third layer).

The control plane is a path through which control messages used by the UE and the network to manage calls are transmitted. The user plane means a path through which data generated in the application layer, for example, voice data or Internet packet data, is transmitted. Hereinafter, the layers of the control plane and the user plane of the wireless protocol will be described.

The physical layer as the first layer provides an information transfer service to an upper layer using a physical channel. The physical layer is connected to the upper layer of Medium Access Control (MAC) layer through a transport channel. Data is transferred between the MAC layer and the physical layer through the transport channel. Data is transferred between the transmitting side and the receiving side physical layer through the physical channel. The physical channel is modulated by an Orthogonal Frequency Division Multiplexing (OFDM) scheme, and uses 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 an upper layer, through a logical channel. The RLC layer of the second layer supports reliable data transmission. The function of the RLC layer may be implemented as a function block inside the MAC. In this case, the RLC layer may not exist. The Packet Data Convergence Protocol (PDCP) layer of the second layer performs a header compression function to reduce unnecessary control information for efficient transmission in an air interface having a narrow bandwidth when transmitting IP packets such as IPv4 or IPv6 .

A Radio Resource Control (RRC) layer located at the bottom of the third layer is defined only on the control plane and includes a configuration, reconfiguration, and release of radio bearers (RBs) And controls the logical channels, the transport channels, and the physical channels. The radio bearer means a service provided by the second layer for data transmission between the UE and the E-UTRAN. To this end, the RRC layer exchanges RRC messages between the UE and the network.

In FIG. 3, the Non-Access Stratum (NAS) layer at the top of the RRC layer performs functions such as session management and mobility management. The NAS layer exists in the Mobility Management Entity (MME) of the UE and the network.

The MME is a key control-node in an LTE access network. The MME is responsible for the tracking and paging procedures for the idle terminal. In addition, the MME participates in the radio bearer activation / deactivation process and is responsible for selecting a Serving Gateway (SGW) at the time of 'Initial Attach' or during an intra-LTE handover including a core network relocation. do. The MME takes charge of terminal authentication through interaction with a Home Subscriber Server (HSS). The NAS signaling is terminated at the MME, and the MME is responsible for creating and assigning a temporary identifier to the terminal. The MME verifies that the terminal has the authority to camp-on the service provider's PLMN (Public Land Mobile Network). MME is the endpoint for encryption / integrity protection for NAS signaling in the network and is responsible for security key management. The MME provides a control plane function for mobility between LTE and 2G / 3G access networks.

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

In the NAS layer, two types of ECM (EPS Connection Management) idle state (ECM_IDLE) and ECM connection state (ECM_CONNECTED) are defined in order to manage signaling connection between the terminal and the EPC, . When an ECM idle terminal establishes an RRC connection with an E-UTRAN, the UE becomes an ECM connected state. ECM An idle MME becomes an ECM connection when it makes an S1 connection with an E-UTRAN. When the UE is in the ECM idle state, the E-UTRAN has no context of the UE. Therefore, the UE in the idle state of the ECM performs a mobility-related procedure based on a terminal such as a cell selection or a cell reselection procedure without receiving a command of the network. On the other hand, when the terminal is in the ECM connection state, the mobility of the terminal is managed by a command of the network. If the location of the terminal is different from the location known by the network in the ECM idle state, the terminal notifies the network of the corresponding location of the terminal through a TA (Tracking Area Update) procedure.

Hereinafter, a handover process in an IEEE 802.16 system, which is an example of a mobile communication system, will be briefly described. A serving base station (SBS) is a base station to which a terminal is currently receiving service, and a target base station (TBS) is a base station to which a terminal is to perform handover. The hard handover synchronizes with the target base station in advance in order to shorten the communication disconnection time during handover. In order to do this, the MS may transmit a MS handover request message to the serving BS. When the MS receives a handover response message from the target BS by transmitting a handover request message to the target BS, And transmits a handover response message in response to the handover request message. The UE obtains information related to the target BS through the MS handover response message, prepares a handover procedure, and transmits a handover direction message to the serving BS. Then, the communication setting is changed according to the target base station, and an action time is waited for receiving a fast ranging information message (Fast_Ranging_IE) from the target base station. The fast ranging information message is a message containing information necessary for the UE to perform ranging process with the target BS, and the Action Time is a time when the candidate target BSs to be handed over promise to transmit the HS- . After receiving the high-speed ranging information message from the target base station, the terminal completes authentication of the terminal through the ranging process and resumes communication. In order to prevent loss of data occurring during communication disruption, the UE, the serving BS, and the target BS buffers the data, transmits and receives the buffered information after the handover is successfully performed, and then continues normal communication. The UE starts buffering at the time of transmitting the UE handover indication message, and the serving BS starts buffering at the time of receiving the UE handover indication message.

With the development of wireless communication technology, handover technology has been developed to support handover between inter-RAT (Radio Access Technology). Even if the terminal moves to a heterogeneous (or heterogeneous) network other than the network in which the terminal is registered, it is a technique for continuously providing services currently used and continuously improving the user's convenience.

In this specification, it is assumed that the first wireless communication chip and the second wireless communication chip are chips for processing and transmitting signals using different wireless communication methods or different wireless connection technology methods. For example, the first wireless communication chip may be a chip that processes signals using the LTE scheme, and the second wireless communication chip may be a CDMA 1x, CDMA 1x EVDO, WCDMA, or eHRPD (evolved high rate packet data) Chip that processes signals, but is not limited thereto. Also, a base station that transmits and receives signals using a first wireless communication scheme (e.g., LTE) with a mobile station may transmit and receive signals using a second wireless communication scheme (e.g., eHRPD) Is referred to as a second type base station. In the present invention, a base station can be used as a concept including a cell or a sector.

5 is a diagram showing an example of the configuration of the terminal 500 according to the present invention.

5, a terminal 500 includes a first wireless communication chip 510, a second wireless communication chip 520, a power amplifier 530, an RF front-end module 540 And an antenna 550. [0034] FIG.

The first wireless communication chip 510 and the second wireless communication chip 520 transmit an original signal (a baseband signal) in a signal transmission process to a signal in a high frequency band And demodulates the received high frequency signal into a baseband signal in a signal reception process. Each of the wireless communication chips 510 and 520 may be implemented as an "RF (Radio Frequency) chip " for modulating a signal processed in a baseband into a signal in a high frequency band, and a baseband chip for processing a baseband signal, RF < / RTI > baseband chip "in which a signal processed in the baseband is modulated in a high frequency band or an RF chip in which a received signal is demodulated into a low frequency band and processed as a baseband signal.

In addition, the first and second wireless communication chips 510 and 520 may be implemented as separate chips as shown in FIG. 5, or may be implemented as a single chip.

As described above, the first wireless communication chip 510 and the second wireless communication chip 520 process the original signal into a signal of a high frequency band during the signal transmission process. On the contrary, in the signal reception process, Band signal and perform modulation / demodulation functions, respectively.

When the terminal 500 needs to simultaneously transmit signals from a plurality of wireless communication chips 510 and 520 to which different wireless communication systems are applied, the first wireless communication chip 510 transmits the original signal in the first frequency band And at the same time, the second wireless communication chip 520 can perform the function of processing the original signal into the signal of the second frequency band. That is, the terminal 500 can transmit signals by modulating signals in different frequency bands in the first and second wireless communication chips 510 and 520 during a signal transmission process. In general, when the terminals 500 transmit signals processed by the first and second wireless communication chips 510 and 520 at the same time, they can transmit signals through different frequency bands.

An interface (not shown) is connected between the first wireless communication chip 510 and the second wireless communication chip 520 to exchange signals and information between components in the terminal 500.

A power amplifier (PA) 530 is used to amplify a received signal, which is processed by the first wireless communication chip 510 and the second wireless communication chip 520 .

The RF front-end module 540 is capable of transmitting / receiving the terminal 500 and enabling a call in various environments. The RF front-end module 540 connects the antenna 550 in the terminal 500 with the first wireless communication chip 510 and the second wireless communication chip 520 to separate the transmission and reception signals . The RF front-end module 540 includes a receiving-end front-end module having a receiving-signal filtering filter as a module for filtering and amplifying and a power amplifier 530 for amplifying a transmitting signal A transmitter front-end module, and the like. The RF front-end module 540 is used for a Global System for Mobile communications (GSM) terminal of a time division multiplexing (TDMA) scheme in which a transmission signal and a reception signal must be switched during a call. Is used.

In addition, the RF front-end module 540 may be used to transmit signals over multiple frequency bands, such as the terminal 500 described in the present invention. For example, the RF front-end module 540 allows the terminal 500 to use the GSM method and the W-CDMA method at the same time. By using this RF front-end module 540, it is possible to reduce the number of parts of the terminal 500 and increase the reliability of the terminal 500, The loss can be reduced.

The RF front-end module 540 reduces power consumption, dramatically improving battery consumption, and enables miniaturization of components of multiple frequency bands, multi-function terminals. 5, the RF front-end module 540 may transmit signals processed in a plurality of frequency bands received from the power amplifier 530 through the antenna 550, respectively .

The antenna 550 transmits a signal to an external device (e.g., a base station) and is shown as one in FIG. 5. However, the terminal 500 may have a plurality of antennas. An RF (Radio Frequency) module may include an RF front-end module 540 and an antenna 550 as a module for transmitting and receiving signals to and from a base station.

The terminal may include a first wireless communication chip 510 and a second wireless communication chip 520 to operate in a dual mode. That is, the first wireless communication chip 510 is in an active state for transmitting and receiving signals with a first type base station (for example, an LTE network base station) using a first wireless communication scheme (for example, an LTE scheme) The second wireless communication chip 520 may operate in an idle mode with a second type base station using a second wireless communication system (e.g., a CDMA system). Alternatively, when the second wireless communication chip 520 operates in an active state for transmitting / receiving signals with the second type base station (for example, the CDMA network base station), the first wireless communication chip 510 transmits the first Type base station and an idle mode.

The handover method between heterogeneous networks according to the present invention operates in an active state in which a first wireless communication chip 510 transmits and receives signals to and from a first type base station using an LTE scheme and a second wireless communication chip 520 ) Is assumed to operate in an idle mode with a second type base station using the eHRPD scheme.

Here, the idle state is a mode in which not only handover but also normal operation is stopped and traffic transmission / reception with the base station is not performed. However, in the idle mode, the UE can perform pilot signal strength measurement for neighboring cells as well as the serving cell (base station), and can transmit paging messages, which are broadcast system messages and system information, . The paging message is a message indicating a paging action to the terminal. For example, paging operations include ranging, network reentry, and the like. Meanwhile, in the active state, the terminal can perform traffic transmission / reception with the base station.

6 is a diagram illustrating a configuration of a terminal apparatus 500 for performing handover between heterogeneous networks according to the present invention.

The configuration shown in FIG. 6 assumes that the first wireless communication chip 510 and the second wireless communication chip 520 are implemented as one integrated wireless communication chip rather than a separate chip. However, it has been described above that it can be constituted by a separate wireless communication chip.

The first type communication module 515 may be provided in a separate first wireless communication chip 510 or an integrated wireless communication chip and the second type communication module 525 may be provided in a separate second wireless communication chip 520. [ Or an integrated wireless communication chip. The first type communication module 515 is used for transmitting and receiving signals to and from a first type base station (for example, an LTE network base station) using the first wireless communication method, and the second type communication module 525 is used for transmitting / (E.g., an eHRPD network base station) that uses a second type of base station (e.

As described above, the terminal 500 including the plurality of wireless communication chips 510 and 520 or the integrated wireless communication chip supporting the plurality of wireless communication systems can operate in the dual mode. For example, when the first type communication module 515 of the terminal 500 transmits / receives a signal to / from a specific first type base station serving as a serving base station in an active state, the second type communication module 525 transmits / May operate in an idle mode or an idle state with the second type base station. The serving base station may send system information related to the measurement of the terminal to the terminal, which allows the terminal to measure the base stations operating in the active state, Measurement may also be performed. That is, the system information may be configured such that the first type communication module 515, in which the terminal remains active, is configured to perform the measurement report on the first type base stations or the second type communication module 525 may also be configured to provide measurement reporting for second type base stations.

After the measurement, the first type communication module 515 of the active terminal 500 transmits a measurement report message to a specific first type base station (hereinafter, referred to as a first type base station A) serving as a serving base station . The measurement report message may include channel quality information for a serving base station, which is a first type base station, and channel quality information for a neighboring cell (or neighbor base station). In addition, the measurement report message includes the second type base stations (the second type base station B, the second type base station C, the second type base station (B), and the second type base station D), etc.) may be further included.

The first type base station A serving as the serving base station can determine whether to perform handover based on the measurement report message. In the measurement report message, if the signal strength between the terminal 500 and the first type base station A is less than a preset threshold value (for example, -70 dB), the first type base station A transmits a handover Can be determined. At this time, if the signal quality between the terminal 500 and the first type base stations is not better than the signal quality between the terminal 500 and the second type base stations, the first type base station A is a second type base station Lt; / RTI >

The first type base station A may transmit the measurement request signal to the terminal 500 together with the list information on the adjacent second type base stations (or the second type cells). Here, the list information may be information on the second type base stations adjacent to the pre-configured first type base station A or information configured based on the measurement report of the terminal. At this time, the list information to be transmitted may include an identifier (ID) (or cell ID) of a second type of base stations (eHRPD base stations, for example), a band class, A plurality of frequencies (for example, 75 MHz, 200 MHz, and 600 MHz) may exist in the use frequency information of a specific second type base station. That is, there is a plurality of frequencies used by one base station, and the terminals use a frequency determined by hashing among a plurality of frequencies arbitrarily through hashing at the time of connection, thereby preventing the terminals from being concentrated at one frequency.

The processor 560 of the terminal 500 receives the list information and a second type base station (hereinafter referred to as a second type base station B) which is in an idle state with the second type communication module 525 of the current terminal 500, ) Can be compared with each other. If the ID of the second type base station (i.e., the second type base station B) that is in an idle state with the second type communication module 525 of the current terminal is included in the received list information, The processor 560 of the second type communication module 525 may perform measurement only on the second type base station B which is in the idle state with the second type communication module 525 among the list information. The first type communication module 515 transmits the measurement result of the second type base station B which is in the idle state with the second type communication module 525 to the first type base station A serving as the serving base station You can do it. At this time, the processor 560 may not compare the used frequency information included in the list information. The processor 560 may not be able to transmit the measured information when the used frequency is different even though it belongs to the same base station, Type base stations (for example, the second type base station B, the second type base station C, etc.). However, the ID (or cell ID), the band class, and the used frequency information of the second type base stations included in the list information and the second type that is in an idle state with the current type 2 communication module 525 When only the frequency of the information of the base station B is different, the first type communication module 515 may transmit only the frequency information to the first type base station A as a measurement report.

Then, the first type base station A may determine to hand over to the second type base station B which is in the idle state with the measured and reported second type communication module 525. The first type base station A transmits a second type base station C other than the second type base station B which is in an idle state to the measured and reported second type communication module 525 to the terminal 500, May be determined as the target base station to be handed over. At this time, the first type base station A may transmit the handover request signal together with the band information (for example, CDMA band) information and the channel information for the second type base station C. That is, the first type communication module 515 transmits band information (for example, CDMA Band) information and channel information for the second type base station C to be handed over from the first type base station A, And may receive a request signal.

In this manner, the second type base station B and the first type base station A, which are currently idle with the second type communication module 525 of the terminal 500, 2 type base stations C are different from each other, the processor 560 performs a handover to the currently acquired cell, i.e., the second type base station B that is in the idle state despite the request of the first type base station A The unnecessary band or frequency of the terminal 500 is not changed, so that the handover time can be shortened and the communication performance can be improved.

While the processor 560 of the terminal performs the measurement, the high data rate sleep duration operates at a maximum of 5.12 seconds. When the first type communication module 515 receives a measurement request signal (e.g., a measurement enable command) from the first type base station A in the case of the 40-second sleep, the processor 560 forcibly sets the HDR state It can be controlled to wake-up.

In addition, when the first type communication module 515 receives the measurement request signal (e.g., Measurement Enable Command) from the first type base station A and the HDR state is the idle state, The first type communication module 515 can transmit the measurement result to the first type base station A at the time of the HDR wake-up by the first type communication terminal.

FIG. 7 is a flowchart illustrating a process of a handover between a heterogeneous network according to a preferred embodiment of the present invention.

7, the serving base station can send system information related to the measurement of the terminal 500 to the terminal. The system information is transmitted to the terminal 500, which is operating in an active state, And may also instruct to perform measurements on base stations that are operating idle. That is, the system information may be configured such that the first type communication module 515, in which the terminal 500 is in an active state, is configured to perform a measurement report on the first type base stations or a second type The communication module 525 may also be configured to provide measurement reporting for second type base stations.

After the measurement is performed, the first type communication module 515 of the terminal transmits the measurement results of the first type base station A and / or the neighbor base stations to the first type base station A through a measurement report message or the like . At this time, the second type communication module 525 operating in the idle state is also connected to the second type base stations second type base stations (for example, the second type base station B, the second type base station C, Type base station (D), etc.) to the first type base station (A). If the signal strength or intensity between the terminal 500 and the first type base station A is less than a preset threshold value (for example, -70 dB), the first type base station A transmits the terminal 500 to another It can decide to hand over to the base station. In addition, when the signal quality between the terminal 500 and the first type base stations is not better than the signal quality between the terminal 500 and the second type base stations, the first type base station A is a second type base station B to determine handover.

Then, the first type base station A may transmit a measurement request signal to the terminal 500 together with the list information on the adjacent second type base stations (or the second type cells) (S710). In other words, the first type communication module 515 of the terminal may measure the second type base station (or second type cell) from the first type base station A (for example, the LTE base station) A request signal may be received (S710). Here, the list information may be information on the second type base stations adjacent to the pre-configured first type base station A or information configured based on the measurement report of the terminal. However, the list information and the measurement request for the second type base stations may be configured in the system information and may be transmitted to the terminal 500, so that the transmission is not limited to the step S710. List information about neighboring second type base stations, measurement request may be given in advance as system information. At this time, the list information to be transmitted may include an identifier (ID) (or a cell ID) of a second type of base stations, a band class, and used frequency information. A plurality of frequencies (for example, 75 MHz, 200 MHz, and 600 MHz) may exist in the used frequency information.

The list information may then be compared with the second type communication module 525 of the current terminal 500 to determine whether the second type of base station B is in an idle state (S720). If the second type base station B that is in an idle state with the second type communication module 525 of the current terminal 500 is included in the transmitted list information, the processor 560 of the terminal 500 The measurement can be performed only for the second type base station B that is in the idle state with the second type communication module 525 of the current terminal 500 in operation S730.

 Thereafter, the first type communication module 515 of the terminal transmits only the measurement results of the second type base station B, which is in an idle state with the second type communication module 525, to the first type base station A (S740). Meanwhile, the processor 560 may not compare the used frequency information included in the list information (S720).

Then, the first type base station A determines to hand over to the second type base station B that is in the idle state with the measured and reported second type communication module 525, and transmits the determined result to the terminal (S750 ). The first type base station A determines the second type base station C and not the second type base station B which is measured and reported by the target base station to which the terminal 500 is to be handed over to the terminal 500 (S750). Although the first type base station A decides to be the second type base station C as the target base station, the processor 560 of the terminal may transmit the second type base station C, which is currently in the idle state with the second type communication module 525, (B) to be handed over. That is, the processor 560 of the terminal controls the second type communication module 525 to perform the handover to the second type base station B that is in the idle state. This is because the unnecessary band or frequency of the terminal is not changed as described above, so that the handover time can be shortened and the communication performance can be improved.

After the processor 560 of the UE determines to perform handover to the second type base station B, the processor 560 of the UE performs a handover procedure to enter the second type BS (S760) . The handover process in step S760 will be described in detail with reference to FIG.

The HDR sleep duration is up to 5.12 seconds while the processor 560 of the terminal performs the measurement. When the first type communication module 515 receives a measurement request signal (e.g., a measurement enable command) from the first type base station A in the case of the 40-second sleep, the processor 560 forcibly sets the HDR state It can be controlled to wake-up.

The first type communication module 515 can transmit the measurement result (or measurement data) to the first type base station A. In addition, when the first type communication module 515 receives a measurement request signal (e.g., a measurement enable command) from the first type base station A, when the HDR status is idle, The first type communication module 515 may transmit the measurement result to the first type base station A.

8 is a flowchart illustrating a detailed procedure of a handover from an LTE base station to an eHRPD base station according to an exemplary embodiment of the present invention.

Referring to FIG. 8, a UE may decide to handover from an E-UTRAN (LTE base station) to an eHRPD base station (shown as 1a in FIG. 8). Then, the MS transmits an HRPD connection request message requesting an HRPD connection to the LTE base station, and the LTE base station forwards the MS message to the MME (see 1b in FIG. 8). The MME sends the P-GW address, the associated APN, and the uplink GRE key with the HRPD connection request message to the eHRPD access node via the S101 tunnel (shown as 1c in FIG. 8). The eHRPD eAN / ePCF then allocates the requested radio resource and sends an A11-Registration Request message to the HSGW (shown as 2a in FIG. 8). In this message, the eHRPD eAN / ePCF includes a P-GW address, an associated associated uplink GRE key received, and an indicator indicating that the terminal is in communication via the tunnel. eHRPD eHRPD In response to the A11-Registration Request message of the eAN / ePCF, the HSGW sends the forwarding address (i.e., HSGW IP address, GRE key, and associated APN) to the eHRPD eAN / ePCF (shown as 2b in FIG. 8) .

The eHRPD eAN / ePCF forwards the HRPD Traffic Channel Assignment (TCA) message from the S101 message to the MME. This S101 message carries the HSGW IP address, the GRE key and the associated APN for data forwarding (shown as 3 in FIG. 8).

The MME constructs resources for indirect data forwarding and sends the HSGW IP address and GRE key to the S-GW. Then, the S-GW confirms the data forwarding resource (shown as 4a in FIG. 8). Thereafter, the MME embeds the HRPD TCA message in the S101 message and forwards it to the E-UTRAN, which is wirelessly forwarded to the terminal (shown as 4b in FIG. 8).

The E-UTRAN returns the downlink IP packet to the SGW via the S103 interface and sends the downlink IP packet to the HSGW. The HSGW performs the necessary processing on the IP packet and forwards the processed IP packet to the eHRPD eAN / ePCF over the A10 connection (shown as 5 in FIG. 8).

Thereafter, the terminal acquires eHRPD radio (L2 attached) (shown as 6a in Fig. 8). Then, the terminal forwards a traffic channel completion (TCC) message to the eHRPD eAN / ePCF (shown as 6b in Fig. 8). The eHRPD eAN / ePCF sends an A11-Registration Request message carrying an active start radio link record with an indicator indicating that the UE is now operating on the eHRPD radio, to the HSGW (7a in FIG. 8) and the HSGW sends an A11- eHRPD eAN / ePCF (7b in Fig. 8).

The HSGW and the S-GW perform a proxy binding update process (8a and 8b in Fig. 8). eHRPD eAN / ePCF transmits a handover completion signal to the MME to confirm handover (HO) completion (8d in FIG. 8). When L3 attach is completed, the terminal can send / receive packets to / from the eHRPD access network (shown as 9 in FIG. 8). The 3GPP EPS resources are then released (shown as 10 in Figure 8).

As described above, after determining the handover from the LTE base station to the eHRPD base station, the UE performs a series of processes for the handover with the eHRPD network, and transmits and receives data to and from the eHRPD network after completion of the handover.

The embodiments described above are those in which the elements and features of the present invention are combined in a predetermined form. Each component or feature shall be considered optional unless otherwise expressly stated. Each component or feature may be implemented in a form that is not combined with other components or features. It is also possible to construct embodiments of the present invention by combining some of the elements and / or features. 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 clear that the claims that are not expressly cited in the claims may be combined to form an embodiment or be included in a new claim by an amendment after the application.

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 or essential characteristics thereof. Accordingly, the above description should not be construed in a limiting sense in all respects and should be considered illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention.

Claims (12)

A terminal apparatus for performing handover between heterogeneous networks,
A first type communication module configured to transmit and receive a signal to and from a first type base station using a first wireless communication method;
A second type communication module configured to transmit and receive a signal to and from a second type base station using a second wireless communication method; And
Type base station through the first type communication module when the measurement request signal including the list information for the at least one second type base station is received from the first type base station through the first type communication module, And a processor for transmitting the result of the performed measurements to the first type base station via the first type communication module,
The processor comprising:
Type base station that is operating in the idle state among the at least one second type base station when the list information includes a specific second type base station operating in an idle state,
And performs handover to a specific second type base station operating in the idle state using the second type communication module among the at least one second type base station. delete delete The method according to claim 1,
Wherein the first wireless communication method includes an LTE (Long Term Evolution)
Wherein the second wireless communication method includes an enhanced high-rate packet data (eHRPD) method. The method according to claim 1,
Wherein at least one second type base station included in the list information corresponds to a base station adjacent to the terminal apparatus. The method according to claim 1,
Wherein the list information includes at least one of band information, identification information (ID) information, and frequency information used for each of the at least one second type base station. delete delete delete delete delete delete

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