KR20050120477A - 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 command of the CDMA1x modem to the DBDM terminal when the active set consists only of the border cell, and the DBDM terminal measures Powering on the CDMA1x modem as the signal strength of the bordered cell satisfies the power-on condition, and the CDMA1x signal strength of the bordered cell measured by the DBDM terminal is determined by the hand. And performing a handover from the WCDMA network to the CDMA1x network as the over condition is satisfied.

More preferably, after powering on the CDMA1x modem, if the border cell belonging to the active set is deleted, the UTRAN is powered off of the CDMA1x modem that is on. Measurement measurement message (Off) is transmitted to the DBDM terminal.

More preferably, after powering on the CDMA1x modem, if the handover to the CDMA1x network is not performed until the expiration of a preset timer, and the best cell is not the border cell, the UTRAN A measurement control message is sent to the DBDM terminal to turn off the power of the CDMA1x modem that is on.

More preferably, the power on command of the CDMA1x modem is transmitted using a measurement control message. Here, the UTRAN further transmits a handover condition to the system of the CDMA1x using the measurement control message. In addition, the UTRAN corresponds to a condition corresponding to an event 2d, which is an inter-RAT event, as the handover condition. The event 3x is an inter-RAT event. Or 3c) informs the DBDM terminal.

In addition, after the CDMA1x modem is powered on, the DBDM terminal checks whether the handover condition is satisfied. At this time, after powering on the CDMA1x modem, if the signal strength of the frequency used by the border cell falls below a certain threshold before expiration of a preset timer, it is determined that the best cell is the border cell. If the best cell is the border cell, the UTRAN hands over the DBDM terminal to a CDMA1x cell superimposed on the border cell. Alternatively, after powering on the CDMA1x modem, if the signal strength of the frequency used by the border cell falls below a certain threshold before expiration of a preset timer, it is determined whether the best cell is the border cell. If the best cell is not the border cell, the DBDM terminal is not handed over to the CDMA1x cell. After the power-on of the CDMA1x modem is turned on, when the handover condition is satisfied, the DBDM terminal reports the fact to the UTRAN using a measurement report message.

More preferably, after powering on the modem for the CDMA1x, if the strength of the frequency currently used by the DBDM terminal is less than or equal to a certain intensity, the DBDM terminal informs the fact that the WCDMA radio network controller (Radio) Network Controller: RNC).

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. It is required for handover of the DBDM terminal to the CDMA1x cell.) As shown in FIG. 2, a border cell overlapping the CDMA1x cell is configured in the boundary region of the WCDMA cell.

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 3a 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.

The DBDM terminal which is in an active state with respect to the WCDMA service (especially the voice call service) moves to a border cell area overlapping the WCDMA cell and the CDMA1x cell (S10).

At this time, that is, when the DBDM terminal moves to the border cell, the UTRAN checks whether the active set consists of border cells only (S11).

Here, when the active set includes only the border cells, the UTRAN transmits a power on command of the CDMA1x modem to the DBDM terminal (S12). At this time, the UTRAN transmits a power on command of the modem for CDMA1x using a measurement control message. The UTRAN further includes a handover condition in a measurement control message along with a power on command of the modem for CDMA1x and transmits the result to the DBDM terminal.

On the other hand, if the border cell belonging to the active set is deleted after the CDMA1x modem is powered on, the UTRAN will turn off the measurement control message for turning off the CDMA1x modem. (Measurement control message) is transmitted to the DBDM terminal.

On the other hand, when the signal strength in the border cell satisfies the power-on condition, the power of the CDMA1x modem is turned on. As another example of the present invention, the DBDM terminal reports to the UTRAN using a measurement report message that the power of the modem for CDMA1x is turned on.

After powering on the CDMA1x modem, if the border cell belonging to the active set is deleted, the UTRAN is a measurement control message for powering off the CDMA1x modem that is on. (Measurement control message) is transmitted to the DBDM terminal.

Also, after powering on the CDMA1x modem, if the best cell is a border cell without performing a handover to the CDMA1x network until expiration of a preset timer, the CDMA1x network overlaps the border cell. Over

On the other hand, if the best cell is not a border cell, the UTRAN transmits a measurement control message to the DBDM terminal to turn off the power of the CDMA1x modem that is on. That is, when the signal strength of the WCDMA cell is higher than the signal strength of the border cell, the UTRAN sends a measurement control message to turn off the power of the CDMA1x modem that is on. Send to

Meanwhile, the UTRAN is a handover condition provided through a measurement control message, and a condition corresponding to an event 2d, which is an inter-RAT event, is a 3D (Event 3a) event. , 3b, or 3c) to inform the DBDM terminal.

Subsequently, after powering on the CDMA1x modem, the DBDM terminal checks whether the handover condition is satisfied.

More specifically, after powering on the CDMA1x modem, if the signal strength of the frequency used by the border cell falls below a certain threshold before expiration of a preset timer, the UTRAN determines whether the best cell is the border cell. Check it. At this time, if the best cell is a border cell, the DBDM terminal is handed over to a CDMA1x cell superimposed on the border cell.

On the other hand, if the best cell is not a border cell, it does not move to the CDMA1x network, and therefore, inter-FA handover is started.

More preferably, after powering on the CDMA1x modem, if the signal strength of the WCDMA cell is less than or equal to a predetermined intensity (A threshold) before expiration of a preset timer (S13), the UTRAN is bound to the best cell. Further check whether the cell (S15). At this time, if the best cell is a border cell, the DBDM terminal is handed over to the CDMA1x cell superimposed on the border cell (S17).

In addition, in the present invention, the UTRAN transmits a relocation required message to the CDMA1x Mobile Switching Center (MSC) for handover of the DBDM terminal to the CDMA1x cell.

On the other hand, while the DBDM terminal is using the CDMA1x modem in the power-on state, if the DBDM terminal is moved and the border cell is deleted from the active set, the UTRAN sends a measurement control message to the DBDM terminal and Turn off the power (S16).

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. When a wideband code division multiple access scheme and the first generation code division multiple access scheme move to overlapped border cell regions and an active set consists only of the border cells, UTRAN is used. Transmitting a power on command of the first generation code division multiple access modem 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. 2. The apparatus of claim 1, wherein, after powering on the first generation code division multiple access method modem, when the border cell belonging to the active set is deleted, the UTRAN is turned on. A measurement control message is transmitted to the dual band dual mode terminal to turn off the power of the first generation code division multiple access modem. Handover method. The method of claim 1, wherein after powering on the first generation code division multiple access method modem, handover to the first generation code division multiple access network is not performed until expiration of a preset timer. And, if the best cell is not the border cell, a measurement control message for powering off the modem for the first generation code division multiple access method in which the UTRAN is on. ) Is transmitted to the dual band dual-mode terminal handover method between heterogeneous communication systems. The method of claim 1, wherein after powering on the first generation code division multiple access method modem, handover to the first generation code division multiple access network is not performed until expiration of a preset timer. And if the best cell is the border cell, handover to the first generation code division multiple access network overlapping the border cell. 2. The handover between heterogeneous communication systems according to claim 1, wherein a power on command of the first generation code division multiple access modem is transmitted using a measurement control message. Way. 6. The method of claim 5, wherein the UTRAN further transmits a handover condition to the first generation code division multiple access system using the measurement control message. Handover method between heterogeneous communication systems. The method according to claim 6, wherein the UTRAN is an inter-RAT event, wherein the condition corresponding to event 2d, which is an inter-FA event, is an inter-RAT event. Handover method between heterogeneous communication systems characterized in that it informs the dual-band dual-mode terminal by the event 3x (Event 3a, 3b or 3c). 7. The heterogeneous method of claim 6, wherein after the power of the first generation code division multiple access method modem is turned on, the dual band dual mode terminal checks whether the handover condition is satisfied. Method for handover between communication systems in a network. 9. The method of claim 8, wherein after powering on the first generation code division multiple access modem, the signal strength of the frequency used by the border cell is less than or equal to a certain threshold before expiration of a preset timer. If falling, check whether the best cell is the border cell, If the best cell is the border cell, the UTRAN is handed over the dual band dual mode terminal to a first generation code division multiple access cell superimposed on the border cell. Handover method. 10. The method of claim 9, wherein after powering on the first generation code division multiple access method modem, the signal strength of the frequency used by the border cell is less than or equal to a certain threshold before expiration of a preset timer. If falling, check whether the best cell is the border cell, If the best cell is not the border cell, handover between heterogeneous communication systems, characterized in that the handover to the first generation code division multiple access network. 10. The method of claim 8, wherein after the power-on of the first generation code division multiple access method modem is turned on, when the handover condition is satisfied, the dual band dual mode terminal measures the fact and reports the fact. Method for handover between heterogeneous communication systems, characterized in that for reporting to the UTRAN (Measurement report message). 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 satisfies the handover condition to the first generation code division multiple access network, the fact is reported to the UTRAN using a measurement report message. And handing over between the heterogeneous communication systems. According to claim 1, If the strength of the frequency currently used by the dual-band dual mode terminal after the power-on of the first generation code division multiple access method modem is less than a certain intensity, the dual band dual And a mode terminal reports the fact to the radio network controller (RNC) of the broadband code division multiple access method.