KR20050120476A - Method for achieving handover between communication systems which are different - Google Patents

Abstract

The present invention relates to a method for handover between heterogeneous communication systems, which enables a mobile terminal to handover from a new network to an established network, in particular in a communication system. Is an invention that enables handover from a new network (WCDMA) network (or system) to an existing network (CDMA1x network) (or system).

Description

Method for achieving handover between communication systems which are different}

The present invention relates to a communication system, and more particularly, to a handover method between heterogeneous communication systems allowing a mobile terminal to handover from a new network to an established network.

In general, it is necessary to go through a transition period in order to evolve from the existing network currently being commercialized to the new network supporting the next generation communication service. This is not a problem if all existing networks are changed to a new network at once, but it is inefficient in terms of cost and time, and since the mobile terminal owned by the user must also be changed, a complete change to a new network is almost impossible at this time. can do.

Accordingly, there exists a communication environment in which the existing network and the new network are mixed, and mobile terminal manufacturers have developed a dual band dual mode terminal (abbreviated as DBDM) to adapt to the mixed communication environment. .

On the other hand, in order to provide both the communication service of the existing network and the communication service of the new network to the user using the DBDM terminal, the continuity of the service currently being received should be guaranteed when the DBDM terminal moves from one network to another.

As described above, it is handover that guarantees the continuity of the service.

In order to perform the handover between heterogeneous communication systems (or networks), the DBDM terminal should be able to search frequencies of two communication systems (or networks) at the same time.

Taking a handover procedure between a conventional network and a new network as an example, conventionally, a wideband code division multiple access (WCDMA) system and a global system for mobile communications (hereinafter, referred to as WCDMA) are described. , GSM for short handover).

In the handover from the WCDMA system to the GSM system, a compressed mode is used to prevent data transmission in the WCDMA for a predetermined time, and the DBDM terminal searches for the frequency of the GSM during the corresponding time.

Accordingly, if the found GSM frequency satisfies the handover condition, the DBDM terminal reports a measurement report message to the UTSRAN (UMTS Terrestrial Radio Access Network).

The UTRAN then sends a Relocation Required message for handover to the GSM system to the Mobile Switching Center (hereinafter referred to as MSC) to initiate a handover to the DBDM terminal.

As described above, there has been a handover scheme from the WCDMA system (or network) to the GSM system (or network).

However, there is currently no technology for handover between a WCDMA system and a first generation code division multiple access (CDMA1x) system.

However, if the prior art uses the handover method between the GSM system (or network) in the above-described WCDMA system (or network) for handover between the WCDMA system and the CDMA1x system, that is, assume that the compressed mode method is used.

However, since the time for not transmitting data in the WCDMA system is shorter than the time required for frequency searching in the CDMA1x system, the handover is impossible even if the compressed mode method is used for handover from the WCDMA system to the CDMA1x system. Accordingly, there is a need for another method for successfully performing handover between a WCDMA system and a CDMA1x system.

An object of the present invention has been made in view of the above points, and in particular, a mobile terminal handovers from a WCDMA network (or system), which is a new network, to a CDMA1x network (or system), which is an established network. It is to provide a handover method between heterogeneous communication systems.

Another object of the present invention is to provide a handover method between heterogeneous communication systems for supporting handover to an existing network forming a nationwide network to ensure continuity of voice service even in a region where a service of a new network is impossible. To provide.

A feature of a handover method between heterogeneous communication systems according to the present invention for achieving the above objects is that a DBDM terminal having a modem for WCDMA and a modem for CDMA1x is a border cell in which the WCDMA and the CDMA1x overlap. UTRAN transmits a power-on condition of the CDMA1x modem and / or a handover condition to the CDMA1x network to the DBDM terminal, and the DBDM terminal measures When the signal strength in the bordered cell satisfies the power-on condition, the power-on of the CDMA1x modem is turned on, and the CDMA1x signal strength in the bordered cell measured by the DBDM terminal is handed over. And performing a handover from the WCDMA network to the CDMA1x network as the condition is satisfied.

More preferably, the UTRAN transmits a power on condition of the CDMA1x modem and / or a handover condition of the CDMA1x system to the DBDM terminal using a measurement control message. Send. At this time, after the DBDM terminal powers on the CDMA1x modem, reporting the fact to the UTRAN using a measurement report message, and the DBDM terminal reports the CDMA1x. After performing the handover to the network, reporting the fact to the UTRAN using a measurement report message.

More preferably, a beacon generator for generating a beacon of the WCDMA is installed in the base station of the CDMA1x.

More preferably, the UTRAN transmits a power on condition of the CDMA1x modem through a system information block 3 (SIB3). Here, the InterRAT ID of the system information block 3 (SIB3) is determined as an identifier of the first generation code division multiple access method. The system further includes a classification condition for the network in the border cell in the InterRAT List of the system information block 3 (SIB3) and transmits the information to the DBDM terminal.

More preferably, the frequency search according to the handover condition uses Event 1a for performing intra-frequency measurement.

Other objects, features and advantages of the present invention will become apparent from the detailed description of the embodiments with reference to the accompanying drawings.

Hereinafter, with reference to the accompanying drawings illustrating the configuration and operation of the embodiment of the present invention, the configuration and operation of the present invention shown in the drawings and described by it will be described by at least one embodiment, By the technical spirit of the present invention described above and its core configuration and operation is not limited.

The present invention proposes a handover procedure between heterogeneous communication systems, and in particular, a handover procedure from a new network to an existing network.

Accordingly, hereinafter, a handover between the WCDMA system and the CDMA1x system will be described as an example.

1 is a diagram illustrating a system configuration for handover between heterogeneous communication systems of the present invention, and FIG. 2 is a diagram illustrating a handover from WCDMA to CDMA1x according to the present invention.

1 and 2, in the present invention, for handover to CDMA1x in a WCDMA system, a mobile terminal is a DBDM mobile station 1 supporting both a WCDMA service and a CDMA1x service.

The WCDMA system includes its own communication system components 10-13, and the CDMA1x system also includes its own communication system components 20-13. In addition, the present invention includes a gateway 30 having a protocol conversion function between the WCDMA system and the CDMA1x system. More specifically, a roaming gateway (RGW) 30 is provided between the WCDMA switch 10 and the CDMA1x switch 20 having a signal message and parameter conversion function.

The components 10 to 13 of the WCDMA system include a WCDMA switch 10, a Radio Network Controller (RNC) 11, a Node B 13, and a Home Location Register (HLR). Register).

The components 20 to 23 of the CDMA1x system include a CDMA1x switch 20, a base station controller (BSC) 21, a base transceiver station (BTS) 23, and a home location register (HLR). (22).

Particularly, in the present invention, the DBDM terminal 1 can measure the signal for the CDMA1x service while receiving the WCDMA service, that is, the DBDM terminal 1 which has been provided with the WCDMA service can receive the CDMA1x frequency. Is required for handover to the CDMA1x cell of the DBDM terminal.), And a beacon generator for transmitting a WCDMA pilot channel to the CDMA1x base station 23 is provided. In other words, in the present invention, by installing a beacon generator for generating and transmitting a WCDMA beacon (= pilot) in the CDMA1x base station 23, the DBDM terminal 1 searches for a signal for the CDMA1x service.

As shown in FIG. 2, the present invention configures a border cell overlapping the CDMA1x cell in the boundary region of the WCDMA cell. For this purpose, a beacon generator for generating a beacon of WCDMA is installed in the base station 23 of the CDMA1x.

Handover to CDMA1x is performed when the DBDM terminal 1 satisfies the handover condition to the CDMA1x cell when it is located in the border cell.

In particular, as shown in FIG. 2, when the signal strength of the CDMA1x cell is greater than or equal to a predetermined level in a region where the WCDMA cell and the newly configured border cell area overlap, the handover is performed. To start. Thereafter, when the DBDM terminal 1 satisfies the power-on condition of the CDMA1x modem when the DBDM terminal 1 is completely located outside the WCDMA cell area and is located only in the border cell, the DBDM terminal 1 activates the CDMA1x modem. That is, power on the CDMA1x modem. The DBDM terminal 1 reports the completion of activation of the CDMA1x modem to the UTRAN.

In addition, the DBDM terminal 1 performs a handover trigger considering an event 1a in a region where the border cell and the serving cell of the CDMA1x base station 23 overlap each other.

Meanwhile, the DBDM terminal 1 may have a single chip configuration for WCDMA / CDMA1x.

On the other hand, the DBDM terminal 1 may have a physical configuration in which a modem for WCDMA and a modem for CDMA1x are separately provided instead of a single chip.

In the case of the DBDM terminal 1 having a WCDMA modem and a CDMA1x modem separately, power is applied to both modems, resulting in a waste of power of the terminal. Apply power.

As a result, the present invention proposes a power on / off scheme for the CDMA lx modem when performing a handover from the WCDMA system to the CDMA lx system, and also proposes a handover triggering scheme.

3 is a flowchart illustrating a handover procedure between heterogeneous communication systems according to the present invention.

Referring to FIG. 3, first, a power on / off method of a WCDMA / CDMA1x modem in a DBDM terminal having a WCDMA modem and a CDMA1x modem will be described.

When a DBDM terminal in an idle state or an active state for a WCDMA service is moved to a border cell area overlapping a WCDMA cell and a CDMA1x cell (S10), UTRAN determines the power of the modem for the CDMA1x. The on condition and / or the handover condition to the CDMA1x network (system) are transmitted, and the corresponding DBDM terminal receives them (S11). More specifically, when the strength of the signal received by the DBDM terminal is more than a predetermined level, a power-on condition of the modem for CDMA1x is provided from the UTRAN.

Thereafter, the DBDM terminal determines whether the measured signal strength in the measured border cell satisfies the power-on condition (S12).

When the signal strength in the measured border cell satisfies the power-on condition, the DBDM terminal turns on the power of the CDMA1x modem (S13), and reports the fact to the UTRAN later.

When the DBDM terminal is in an active state with respect to voice call service of WCDMA, the UTRAN uses a measurement control message to power on a modem for CDMA1x. Condition and / or handover condition to the network (system) of CDMA1x. At this time, after the DBDM terminal powers on the modem for CDMA1x, the DBDM terminal reports the fact to the UTRAN using a measurement report message. At this time, the UTRAN drives the handover timer to handover the DBDM terminal to the CDMA1x cell superimposed on the border cell when the handover timer expires while being between the CDMA1x power off condition and the handover condition.

On the other hand, the DBDM terminal, which is in an active state with respect to voice call service of WCDMA, performs a handover to the CDMA1x network, and then reports the fact (handover completion) to a measurement report message (Measurement report message). Report to UTRAN. In addition, the DBDM terminal distinguishes whether the cell is a border cell, a WCDMA cell, or a CDMA1x cell by using neighboring cell information received through a measurement control message from the UTRAN. That is, the DBDM terminal heterogeneously has a cell ID identical to the identifier ID of a CDMA1x cell, which is a WCDMA beacon cell, among neighbor cell information provided from UTRAN through intra-frequency cell information of a measurement control message. Cells are distinguished by being provided through InterRAT Cell Info. Accordingly, the DBDM terminal determines a primary scrambling code using the same cell ID included in the intra-frequency cell info as a CDMA1x cell, which is a WCDMA beacon cell.

On the other hand, when the DBDM terminal is in an idle state for the communication service of WCDMA, the UTRAN transmits the power on condition of the modem for CDMA1x through the System Information Block 3 (SIB3). do. In this case, SIB3 is a type of information (message) transmitted through an overhead channel.

Particularly, in the present invention, when the DBDM terminal is in an idle state for the communication service of WCDMA, the Inter Radio Access Technology Identifier (InterRAT ID) of the SIB3 is defined as the identifier of the CDMA1x, and the UTRAN of the SIB3 is used. In addition, a classification condition for the network in the border cell is further included in the Inter Radio Access Technology List (InterRAT List) and transmitted to the DBDM terminal. For example, the selection condition (signal strength) for the border cell is included in the InterRAT List and transmitted to the DBDM terminal.

Subsequently, the DBDM terminal, which is in an idle state for the communication service of WCDMA, periodically measures a frequency and satisfies a power-on condition, and turns on the power of the CDMA1x modem by itself.

On the other hand, the DBDM terminal in the idle state is a system information block 11 (SIB11) to distinguish whether the signal to be measured corresponds to a border cell, a beacon cell (CDMA1x cell) or a WCDMA cell. Use neighbor cell information that comes down. In more detail, the DBDM terminal heterogeneously radios a cell identifier (ID) that is identical to the identifier (ID) of the CDMA1x cell, which is a WCDMA beacon cell, among neighbor cell information provided from the IBRAN through the intra-frequency cell info of the SIB11. It is provided through InterRAT Cell Info. Thus, the DBDM terminal determines a primary scrambling code (PSC) using the same cell identifier (ID) in the intra-frequency cell information as a CDMA1x cell, which is a WCDMA beacon cell.

Meanwhile, the DBDM terminal which is in an idle state or an active state for the WCDMA service determines whether the measured CDMA1x signal strength in the measured border cell satisfies the handover condition (S14). If the signal strength of the measured border cell satisfies the handover condition, the DBDM terminal performs handover from the WCDMA network to the CDMA1x network (S15).

In addition, in the present invention, after the DBDM terminal in the idle state turns on the power of the CDMA1x modem as described above, the DBDM terminal immediately registers the location registration to the CDMA1x network (CDMA1x HLR). Perform. Then, the power of the WCDMA modem is turned off.

On the other hand, during a voice call, the DBDM terminal turns off the power of the CDMA1x modem when the signal strength of the CDMA1x cell, which is the WCDMA beacon cell, drops below a certain level while using the CDMA1x modem that is in the on state. Inform the UTRAN via the Measurement Report Message.

The following describes a handover triggering scheme from the WCDMA network to the CDMA1x network.

As already mentioned above, when a DBDM terminal receiving a WCDMA voice call service moves to a border cell, the UTRAN transmits a Measurement Control Message to power-on and / or handover conditions of the CDMA1x modem of the DBDM terminal. To provide.

Accordingly, after the CDMA1x modem is powered on, the DBDM terminal measures the signal strength of the CDMA1x cell, which is the beacon cell of WCDMA, and satisfies the handover condition, and transmits a measurement report message to the UTRAN and transmits it to the CDMA1x network. Starts handover.

On the other hand, the frequency search based on the handover condition uses Event 1a which performs intra-frequency measurement. When the event 1a condition is provided to the DBDM terminal, the event 1a is generated when the DBDM terminal sufficiently moves to the CDMA1x cell region, which is the WCDMA beacon cell region, by using an individual offset value.

According to the present invention described above, a handover from the new WCDMA network to the CDMA1x network forming a nationwide network is possible, so that the shadow area that the WCDMA service does not reach (the area where the existing CDMA1x system is in charge of service) Guarantees service continuity for voice services.

In particular, when the handover scheme from the WCDMA system described in the present invention to the CDMA1x system is satisfied, the 3GPP standard is satisfied, and therefore, a handover function from WCDMA to CDMA1x can be provided within the 3GPP standard range.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

1 is a diagram illustrating a system configuration for handover between heterogeneous communication systems of the present invention.

2 is a diagram for explaining handover from WCDMA to CDMA1x according to the present invention;

3 is a flowchart illustrating a handover procedure between heterogeneous communication systems according to the present invention.

Claims (13)

A dualband dualmode terminal having a modem for a wideband code division multiple access (WCDMA) and a modem for a first generation code division multiple access (CDMA1x) is described above. As the wideband code division multiple access scheme and the first generation code division multiple access scheme move to overlapped border cell regions, the UTRAN is turned on by the modem for the first generation code division multiple access scheme. transmitting a power on condition and / or a handover condition to the first generation code division multiple access network to the dual band dual mode terminal; Turning on power of the first generation code division multiple access modem as the signal strength in the border cell measured by the dual band dual mode terminal satisfies the power on condition; The first generation code division multiple access scheme in the wideband code division multiple access scheme as the first generation code division multiple access scheme signal strength in the border cell measured by the dual band dual mode terminal meets the handover condition Handover method between heterogeneous communication systems comprising the step of performing a handover to the network. The method of claim 1, wherein the UTRAN is a power on condition and / or the first generation code division of the first generation code division multiple access method using a measurement control message (Measurement control message) A handover method between heterogeneous communication systems characterized by transmitting a handover condition to a system of a multiple access method to the dual band dual mode terminal. The method of claim 1, wherein after the dual-band dual-mode terminal powers on the first generation code division multiple access modem, the fact is determined using a measurement report message. Reporting to UTRAN, After the dual band dual mode terminal performs a handover to the first generation code division multiple access network, reporting the fact to the UTRAN using a measurement report message. Handover method between heterogeneous communication systems further comprising. The mobile station of claim 3, wherein the dual-band dual-mode terminal is configured to transmit the broadband data from neighbor cell information provided through intra-frequency cell information of a measurement control message from the UTRAN. Receiving a cell ID identical to a cell ID of a first generation code division multiple access method, which is a beacon cell of a code division multiple access method, through interRAT Cell Info. A handover method between heterogeneous communication systems. The broadband code of claim 4, wherein the dual band dual mode terminal uses a primary scrambling code that uses the same cell ID included in the intra-frequency cell information. A handover method between heterogeneous communication systems, characterized in that it is determined as a cell of a first generation code division multiple access method that is a beacon cell of a split multiple access method.  2. The handover method between heterogeneous communication systems according to claim 1, wherein a beacon generator for generating a beacon of the wideband code division multiple access method is installed in the first generation code division multiple access base station. . The method of claim 1, wherein the UTRAN transmits a power on condition of the first generation code division multiple access modem through a system information block 3 (SIB3). Handover method between heterogeneous communication systems. [8] The method of claim 7, wherein the classification information for the network in the border cell is further included in the interRAT list of the system information block 3 (SIB3) and transmitted to the dual band dual mode terminal. Handover method between heterogeneous communication systems. 8. The neighbor cell of claim 7, wherein the dual band dual mode terminal is provided from the UTRAN through intra-frequency cell information of a system information block 11 (SIB11). 9. Method of handover between heterogeneous communication systems, characterized in that the cell ID (cell ID) that is the same as the identifier (ID) of the border cell of the information is provided through the inter-RAT Cell Info (InterRAT Cell Info). 10. The apparatus of claim 9, wherein the dual band dual mode terminal uses a primary scrambling code that uses the same cell ID included in the intra-frequency cell information to the border cell. Handover method between heterogeneous communication systems, characterized in that determining. The method of claim 1, wherein after the power of the first generation code division multiple access method modem is turned on, the dual band dual mode terminal is located in the first generation code division multiple access network. And powering off the modem for the wideband code division multiple access method. The handover method of claim 1, wherein the frequency search based on the handover condition uses an event 1a for performing intra-frequency measurement. The method of claim 1, wherein after the power of the first generation code division multiple access modem is turned on, the dual band dual mode terminal turns off the power of the first generation code division multiple access modem. If the timer expires while the handover condition to the beacon cell of the wideband code division multiple access method is not satisfied, the CDMA1x network overlaps the border cell. How to handover.