KR20120076977A - Method for call retrying and mobile telecommunication system for the same - Google Patents

Abstract

PURPOSE: A call reattempt method and a mobile communication system for the same are provided to increase a call success rate of a terminal and to reduce resources of a communication network. CONSTITUTION: A local switch transmits a message to a destination exchange(40) when obtaining a subscriber roaming number. The terminal receives a response from the destination switch. The terminal sets up a CSMT(Circuit Switched fallback Mobile Terminated call flag) to the destination switch. The terminal performs location registration. The destination switch performs location registration to an HLR(Home Location Register)(20).

Description

Call retry method and mobile communication system therefor {METHOD FOR CALL RETRYING AND MOBILE TELECOMMUNICATION SYSTEM FOR THE SAME}

The present invention relates to the field of mobile communications, and more particularly, to an incoming call retry method of an exchange for increasing the success rate of an incoming call of a mobile terminal in a boundary section of the exchange and a mobile communication system therefor.

CSFB (circuit switching fallback) is a mobile terminal that has been serviced in a long term evolution (LTE) evolved-universal terrestrial radio access network (E-UTRAN) cell region and falls back to a circuit switching (CS) domain. The mobile communication service provider may configure the terminal and the network to receive the voice call service.

In case of a general CSFB incoming call, the switch that the first incoming call is attempted requests the paging of the CSFB incoming through the SGs interface to the terminal of the corresponding LTE region, and the terminal of the LTE region moves to the WCDMA cell to perform the CSFB and performs a paging response. The incoming call is made.

However, when the terminal moved to the WCDMA cell to perform the CSFB incoming call at the exchange border area is different from the exchange to which the incoming call is attempted, that is, when the exchange location changes, the incoming call fails. 3GPP TS 23.272 proposes the following recommendations as MT Roaming retry for CSFB to increase the success rate of incoming calls due to such exchange change. 1 is an exemplary view illustrating a roaming retry procedure according to 3GPP TS 23.272.

The gateway mobile switching center (GMSC), the home location register (HLR), and the OldMSC perform the New Roaming Retry (MT) Roaming Retry procedure to perform the incoming call to the NewMSC when the terminal changes the switch location during the paging of the incoming call. To perform.

When the OldMSC receives an IAM (initial address message) and receives a MAP Cancel Location message while performing incoming paging, the OldMSC sends a MAP Resume Call Handling message to the gateway mobile switching center (GMSC) to request to resume the incoming call. The GMSC disconnects the ISDN user part (ISP) connection from the OldMSC, performs second send routing information (SRI) with the HLR, acquires a roaming number (MSRN), and attempts an incoming call to the NewMSC.

As described above, the existing MT Roaming retry for CSFB procedure requires the support of the GMSC and the HLR according to the additional operation performed by the local exchange and the Resume Call Handling, which causes a problem of resource occupancy and load of the communication network.

The present invention provides an incoming call retry method of an exchange for increasing an incoming call success rate of a mobile terminal in a boundary section of an exchange, and a mobile communication system therefor.

The mobile communication system according to the present invention transmits a message used by a local exchange that an incoming call is attempted to obtain a subscriber roaming number to a destination exchange before a terminal moving from a cell boundary to another cell moves to the other cell, and responds from the destination exchange. Receive

In addition, the call retry method of the present invention comprises the steps of: a) moving the terminal from the cell boundary to another cell; b) transmitting, by the local exchange that the incoming call is attempted from the terminal when the mobile terminal moves to another cell, a message used to obtain a subscriber roaming number to the destination exchange; And c) the local exchange receiving a response from the destination exchange.

According to the present invention, there is no change in the existing call processing operation of GMSC and HLR, so it is not necessary to send and receive additional GMSC and HLR message, and the incoming call retry by CSFB according to processing of PRN (provide roaming number) operation in local exchange. Substituting as much as possible reduces the resources and load of the network.

1 illustrates an example roaming retry procedure according to 3GPP TS 23.272.
2 is an exemplary view showing an incoming call retry procedure according to an embodiment of the present invention.
3 is an exemplary view showing a PRN message transmission method according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions will not be described in detail if they obscure the subject matter of the present invention.

The present invention provides a CSFB (circuit switching) in which a mobile terminal provided with a service in an evolved-universal terrestrial radio access network (E-UTRAN) cell area provides a voice call service by falling back to a circuit switching (CS) domain. A system capable of providing fallback, a circuit switching domain consisting of a gateway mobile switching center (GMSC), a home location register (HLR), and an MSC server and an E-UTRAN base station (eNB). And a system including a MME (Mobility Management Entity), to change the conventional MT Roaming retry for CSFB method to reduce the resources and load of the communication network.

In the general CSFB call processing procedure, the local exchange (OldMSC) that attempted the first incoming call requests the CSFB incoming paging through the SGs interface to the terminal of the region, and the terminal of the E-UTRAN region performs the CSFB. In order to do this, an incoming call is made by moving to a wideband code division multiple access (WCDMA) cell and performing a paging response.

However, when the UE moved from the LTE E-UTRAN cell to the WCDMA cell to perform the CSFB incoming call at the exchange boundary area is different from the local exchange to which the incoming call is attempted and the destination exchange moved by the UE is changed. According to the procedure as shown in 2, the incoming call to the destination exchange where the location registration has occurred is successful.

First, the local exchange (OldMSC) 30, which is an exchange to which an incoming call is attempted before the terminal 60 moves, attempts an incoming call (S10 to S50) to the terminal 60 of the corresponding LTE E-UTRAN region through the CSFB through the SGs interface. Incoming paging request (S60, S70), the terminal 60 in the LTE E-UTRAN region moves to the WCDMA cell to perform the CSFB to perform a paging response.

In this case, when the exchange location of the terminal 60 moved to the WCDMA cell in the border area is changed, the terminal 60 sets a circuit switched fallback mobile terminated call flag (CSMT) to the destination exchange (NewMSC) 40 of the region. Performing location registration by the CSFB incoming (S80), the destination exchange 40 performs the location registration to the HLR (20) (S90).

The HLR 20 sends a MAP_CancelLocation message including the destination exchange 40 number to the local exchange 30 to perform location registration of the destination exchange 40 (S100), and the local exchange 30 confirms. (Ack) When the message is sent to the HLR 20 (S110), the HLR 20 transmits an InsertSubscriberData (subscriber information transfer) message to the destination exchange 40 (S120, S130). Thereafter, the HLR 20 transmits a location registration confirmation (UpdateLocationAck) message to the destination exchange 40 (S140).

The local exchange 30 transmits the MAP_ProvideRoamingNumber message to the destination exchange 40 using the destination exchange 40 number included in the reception of the MAP_CancelLocation message during paging (S150), and the destination exchange 40 receives the subscriber roaming number (MSRN). Respond with a MAP_ProvideRoamingNumber acknowledgment (Ack) message including the mobile subscriber roaming number (S160).

In addition, the local exchange 30 refers to the subscriber roaming number included in the PRN message and transmits an IAM (initial address message) message to the destination exchange 40 for incoming call processing (S170).

In response to receiving the IAM message, the destination exchange 40 transmits a setup message to the terminal 60 when CSMT is set in the corresponding subscriber terminal 60 (S180) and proceeds with the incoming call processing (S190).

3 is an exemplary view showing a PRN message transmission method according to an embodiment of the present invention. The PRN message is used when obtaining a VLR (visit location register) subscriber roaming number (MSRN) registered in the destination exchange 40. The HLR 20 receives the send routing information (SRI) message and then the destination exchange 40. In the present invention, there is a difference in that the local exchange 30 directly transmits and transmits a PRN message. In order to perform this function, the HLR 20 should transmit to the local exchange 30 including the destination exchange 40 number in the MAP_CancelLocation message when performing the location registration procedure, and when receiving the MAP_CancelLocation message, the local exchange 30 receives the destination exchange. Send a PRN message to 40 to obtain the MSRN and send an IAM to the destination exchange 40;

While the above methods have been described through specific embodiments, the methods may also be implemented as computer readable code on a computer readable recording medium. Computer-readable recording media include all kinds of recording devices that store data that can be read by a computer system. Examples of the computer-readable recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like, and may be implemented in the form of a carrier wave (for example, transmission over the Internet) . The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. In addition, functional programs, codes, and code segments for implementing the above embodiments can be easily deduced by programmers of the present invention.

Although the present invention has been described in connection with some embodiments thereof, it should be understood that various changes and modifications may be made therein without departing from the spirit and scope of the invention as understood by those skilled in the art. something to do. It is also contemplated that such variations and modifications are within the scope of the claims appended hereto.

10: GMSC 20: HLR
30: OldMSC 40: NewMSC
50: SAE / LTE 60: terminal

Claims (8)

As a mobile communication system,
A mobile communication system for transmitting a message used by a local exchange that an incoming call is attempted to obtain a subscriber roaming number to a destination exchange and receiving a response from the destination exchange before the terminal moving to another cell from a cell boundary. The method of claim 1,
The terminal performs location registration by setting a circuit switched fallback mobile terminated call flag (CSMT) to the destination exchange,
The destination exchange system performs a location registration with a home location register (HLR). The method of claim 2,
The home location register sends a location cancellation message including the destination exchange number to the local exchange after performing location registration of the destination exchange,
The local exchange receiving the location cancellation message and sending a confirmation message to the home location register. The method of claim 3,
The local exchange transmits the subscriber roaming number to the destination exchange by using the MAP_ProvideRoamingNumber message to the destination exchange by using the destination exchange number included when the location cancellation message is received.
The terminating exchange responds to the local exchange with a MAP_ProvideRoamingNumber acknowledgment message. As a call retry method,
a) moving the terminal from one cell boundary to another cell;
b) transmitting, by the local exchange that the incoming call is attempted from the terminal when the mobile terminal moves to another cell, a message used to obtain a subscriber roaming number to the destination exchange; And
c) receiving a response from the destination exchange by the local exchange. The method of claim 5,
The step b)
b1) the terminal performing location registration by setting a circuit switched fallback mobile terminated call flag (CSMT) to the destination exchange; And
b2) the destination exchange performing a location registration with a home location register (HLR). The method of claim 6,
After step b2),
b3) the home location register sending a location cancellation message including the called exchange number to the local exchange; And
b4) the local exchange further comprising receiving the location cancellation message and sending a confirmation message to the home location registrar. The method of claim 7, wherein
And the local exchange transmits the subscriber roaming number to the destination exchange using the MAP_ProvideRoamingNumber message to the destination exchange using the destination exchange number included in the reception of the location cancellation message, and receives a response with a MAP_ProvideRoamingNumber confirmation message.

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