KR100330246B1 - Method of automatically reconnecting a dropped call in mobile communication system - Google Patents

Abstract

The present invention automatically reconnects an existing call by a method of location registration when a call connection failure occurs due to an unserviceable condition of a call in a mobile communication system. The present invention relates to a mobile communication system having a plurality of base stations and a plurality of mobile switching stations, wherein at least one of the plurality of base stations connected to a mobile station of a subscriber and at least one of the plurality of mobile switching stations connected to the connected base station is provided. A method of reconnecting a service between a subscriber's mobile terminal and a subscriber's terminal during service failure with a subscriber's terminal through a mobile switching center, the method comprising: registering a location from the mobile terminal of the subscriber when the service fails When a request message is received by one of a plurality of base stations and a mobile switching station connected thereto, the mobile switching center searches for a location registration device that has registered a previous location of the mobile terminal, and the mobile terminal registered with the found location registration device. Determining whether the information is in service; If the status of the beams service said mobile switching center is made by attempting to reconnect for a paging to the mobile terminal by the process of the mobile terminal of the subscriber and the subscriber of the terminal blood resume the service.

Description

Method of automatic reconnection in case of call failure in mobile communication system {METHOD OF AUTOMATICALLY RECONNECTING A DROPPED CALL IN MOBILE COMMUNICATION SYSTEM}

The present invention relates to a mobile communication system, and more particularly, to a method for reconnecting a call in case of a call connection failure.

In general, public land mobile networks (PLMNs) are connected to mobile stations and base stations in a wireless environment unlike wired switched networks. In radio-based communication, call service may be impossible due to the influence of the surrounding environment during propagation of shadowed areas or eletric waves due to the characteristics of radio waves. In particular, in a mobile telephone network, a subscriber having a terminal may move a location by using a walk or a vehicle. In this case, temporary disconnection may occur due to the characteristics of the radio wave. When such a phenomenon occurs, in the prior art, if the call unavailable state is maintained for a predetermined time, it is determined that the call service is impossible and releases the call. As an example of the above-defined time, IS-95 sets it to about 5 seconds (= 20 ms x 270 one frame period). When the call is released in this undesired state, the calling party has the inconvenience of having to retry the call from the beginning in order to access the call with the previous counterpart.

As a method for improving such inconvenience, there are one example as follows.

First, U.S. Patent No. 5,546,382 discloses a reconnection method for a line for providing continuous service in the event of a transmission failure in data communication.

U. S. Patent No. 5,239, 571 discloses a method for reconnection when a call is released due to abnormal termination in mobile communication. The method is implemented through modification of the terminal or an additional device of the terminal. That is, it is a technology that automatically sets up a call in case of abnormality by storing information of origination and reception by using RAM (RAM) inside the terminal.

In addition, US Patent No. 5,566,236 discloses a method of introducing an intelligent network concept and reconnecting with a telephone connected to a nearby telecommunication system (private switch and Centrex) when a call is disconnected.

An object of the present invention is to provide a method for automatically reconnecting a call by a method of location registration when a call failure occurs during a call service in a mobile communication system.

Another object of the present invention is to provide a method for automatically reconnecting a call by a method of location registration during a call failure in a mobile communication system.

In the present invention, " during call service " is defined as a state in which voice communication and data communication services such as audio, still picture, and moving picture are provided. In addition, in the present invention, a call when a temporary call unavailable state or a continuous call unavailable state is caused is defined as a "drop call", and the temporary call unavailable state is called a call connection failure or call failure. There are various kinds of fault calls defined above, such as truncation (unidirectional, bidirectional) calls, noise of specific channels, out of service, and the like. Here, the cut call means that the call is cut in a predetermined time.

1 is a configuration diagram of a mobile communication system applied as an example according to an embodiment of the present invention;

2 is a call processing flow diagram for releasing a disability call according to an embodiment of the present invention;

3 is a detailed control flowchart performed by an MS according to an embodiment of the present invention;

4 is a detailed control flowchart performed by a BS according to an embodiment of the present invention;

5 is a detailed control flowchart performed by an MSC according to an embodiment of the present invention;

6 is a call processing flowchart for performing a procedure by the existing paging method specified in IS-634,

7 is a detailed control flowchart performed by the VLR according to an embodiment of the present invention;

8A to 8C are flowcharts of a mobile terminal subscriber performing a call automatic reconnection after moving to a current MSC service area after a call failure occurs in a previous MSC service area;

9 is a call processing transition diagram according to the prior art,

10 is a call processing state transition diagram according to an embodiment of the present invention,

11 is a configuration diagram of a format of a "Registration Notification Return Result" signal including a reconnection flag according to an embodiment of the present invention;

12 is a view showing a structure in which "MSD ID" and "Location Area ID" are added to "Registration Cancellation", that is, a location registration deletion command message prescribed by IS-41, etc .;

13 is a view showing a structure of a registration reconnection message according to an embodiment of the present invention;

14 is a structural diagram of a BS side for detecting a call failure;

15 is a diagram illustrating an example in which a corresponding paging area and a corresponding cell are configured as a paging area for reconnection paging;

16 illustrates an example of using an intersystem page according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same elements in the figures are denoted by the same numerals wherever possible. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

According to an embodiment of the present invention, a system applied as an example is a digital mobile communication system using a North American method. Standards used in North American methods include IS-95, IS-634, and IS-41. In particular, the present invention is applicable to 3G (3rd Generation) IS-95 capable of transmitting high-speed data as well as voice. 3G IS-95 provides high quality voice, moving picture and internet search.

An example of a mobile communication system applied according to an embodiment of the present invention is a home location register (HLR) 80, a mobile switching center (MSC) 70, a base station controller (BSC) 64, a BTS (as shown in FIG. 1). Base station Transceiver Subsystem (62) and Mobile Station (MS) 50. In one Public Land Mobile Network (PLMN), several HLRs and MSCs interwork with each other to perform subscriber management and call exchange functions. As shown in FIG. 1, multiple MSCs 70 are connected to one HLR 80 (MSC0 70a and MSC1 70b in FIG. 1), and multiple BSC 64s may be connected to one MSC 70 (eg, MSC0). BSC00 64a and BSC01 64b may be connected to 70a, and a plurality of BTS 62s may be connected to one BSC 64 (for example, BTS000 62a and BTS001 62b to BSC00 64a). In general, the BSC 64 and the BTS 62 are collectively referred to as a base station (BS) 60.

Referring to the functions of the components of FIG. 1 in more detail, MSC 70 performs control to connect with BSC 64, Public Switch Telephone Network (PSTN) and PLMN (PLMN), BSC 64 is a wireless Performing link and radio link control and handoff functions, the BTS 62 performs a function of configuring a radio channel and managing radio resources with the MS 50, and the HLR 80 performs a subscriber location registration function. The VLR (Visitor Location Register) 72a, b is a database that temporarily stores information of the MS 50 existing in the area that the MSC (ie, MSC0 70a and MSC1 70b) is in charge of. If the MS 50 leaves other areas, the stored information is deleted.

In the above mobile communication system, when a call is established, the corresponding MS 50 and BTS 62 allocate a radio channel, and BTS 62 and BSC 64, BSC 64 and MSC 70, MSC 70 and its own network or external network (for example, PSTN) Allocate the call routes of and connect them to make a call. When a call is established and in a call, when a call cannot be maintained for a certain time due to a wireless environment or a shadow area, the call is forcibly terminated by a general mobile communication system. Examples of situations in which a call cannot be maintained for a certain time period include elevators, tunnels without relays, long tunnels located between adjacent cells, and radio shading areas in high-rise buildings.

Such a situation becomes a position where a failure call defined in the embodiment of the present invention can be generated, and the position can be classified into the case of reference numerals 10, 12, 14, and 16 shown in FIG.

Positions 10, 12, and 14 are located in the region of the MSC having the same fault generating position (MSC0 70a in FIG. 1), and positions 16 are BTSs of MSCs having different faulting positions (MSC0 70a in FIG. 1). Is between BTS011 62d and BTS100 62e of MSC1 70b). On the other hand, among the call generation locations in the same MSC area (MSC0 70a), the reference number 10 indicates that the call has occurred between the BTS000 62a and the terminal in the area of the BTS (BTS000 62a), and the reference number 12 is the same BSC ( In the area covered by the BTSs (BTS000 62a and BTS001 62b in FIG. 1) of BSC00 64a, a failure call has occurred between terminals talking to either BTS 62a or 62b, and reference numeral 14 is in the same MSC (MSC0 70a). An inter-terminal call, which is in communication with one BTS, occurs between an area that is in charge of BTSs (BTS001 62b and BTS010 62c in FIG. 1) connected to other BSCs (BSC00 64a and BSC01 64b), respectively.

A method for reconnecting a call when a call is generated is disclosed in detail in patent application No. 98-13789, which was invented by the inventor Chun Kyung-joon and assigned to the applicant.

On the other hand, in the embodiment of the present invention, when a disability call occurs, the above-mentioned patent application No. 98-13789 (need to be changed to an overseas application number when translated into English: PCT application number PCT / KR99-00183 (1999.4.17) of the present case The call is reconnected through a location registration method different from the location registration method.

2 is a call processing flow diagram for releasing a fault call and reconnecting a call according to an embodiment of the present invention. 3 is a detailed control flowchart performed by an MS according to an embodiment of the present invention, FIG. 4 is a detailed control flowchart performed by a BS according to an embodiment of the present invention, and FIG. 5 is a flowchart of an MSC according to an embodiment of the present invention. Detailed control flow chart to perform. 7 is a detailed control flowchart performed by the VLR according to an embodiment of the present invention.

A method of reconnecting a call when a call failure occurs according to an embodiment of the present invention will now be described with reference to FIGS. 2, 3 to 5, and 7.

If a call is established and is in a call service (in a call) state and the traffic channel that was in a call service (in a call) is disconnected, the MS and BS determine whether a call failure has occurred. The MS and BS determine the call service (calling) state (step 300 of FIG. 3 and step 400 of FIG. 4). The MS and BS then determine if a call failure occurred if the traffic channel was disconnected (step 302 of FIG. 3 and step 402 of FIG. 4). The MS and BS, as disclosed in the prior patent application Nos. 98-13789, have not received the frame in the current traffic channel for a preset time value (1 second to 10 seconds) or errors are received continuously in succession. If it is determined that the call failure occurred. As for the said preset time value, about 1-2 second is preferable. It can be seen that the time value 1,2 seconds set to detect the call failure is less than about 5 seconds, which is a time value defined when the existing call is released.

A more detailed description of how the MS and BS detects a call failure is as follows.

The structure of the BS side for detecting call failure is shown in FIG. Referring to FIG. 14, the CDMA radio wave received by the antenna 100 is converted into an intermediate frequency IF through RF & XCVB (Radio Frequency & Tranceiver Block) 102. The converted intermediate frequency IF is composed of packets of QCELP (Qualcomm Code Excited Linear Predictive coding) scheme in CMDMA (CDMA Mod. And Demod. Block) 104. In this operation, the CMDB 104 checks whether a packet (frame) is normally present as follows.

-Cyclic Redundancy Code (CRC) Check

-Check the brokenness of the frame

In the CMDB 104, a value indicating whether the CRC is normal and a value indicating the brokenness of the frame (Quality Matrix: H'00 to H'ff) are included in the transform frame (constructed packet) and transmitted to the TSB (transcoder) 106. In TSB 106, when the value indicating whether the CRC is normal or the value indicating the brokenness of the frame (Quality Matrix: H'00 to H'ff) is "0", the TSB 106 determines that it is abnormal and performs the corresponding operation. In the case of "1", processing proceeds normally. In normal processing, the received frame is converted into PCM (Pulse Code Modulation) and transmitted to the MSC.

If the TSB 106 determines to be in an abnormal state, it plays a role of counting consecutive occurrences of errors and unreceived frames to determine whether there is a final failure. TSB 106 uses the timer interrupt generated every 20ms as a criterion for determining whether a frame is received. In other words, it checks whether a frame is received every 20ms interrupt.

TSB 106 determines that a failure is initiated when 20 frames of an error state, that is, a bad frame, are output from the CMDB 104. After that, if a predetermined number of failure frames are continuously received, the failure is detected. If it is assumed that the time value set to detect a call failure is 2 seconds, it will be determined as a call failure when receiving 80 consecutive frames in error state. However, if two or more consecutive normal frames are received while detecting a fault, the counter counting the bad frames is initialized and returned to normal state. On the other hand, TSB 106 determines that the failure is started when there are no frames transmitted from CMDB 104, that is, when 20 no frames are continuous. If no frame continues, it is determined as a call failure. It is preferable that the time point for declaring a call failure during continuous reception of no frames is shorter than the time point for declaring a call failure during continuous reception of error frames.

An example of a method for detecting call failure in an MS is as follows. When the MS is in terminal control on the call channel, it always monitors the forward call channel. If the MS receives L (L is a natural number) bad frames continuously in the forward communication channel, the transmitter stops the transmitter operation. Thereafter, when the MS continuously receives M good frames (M is a natural number), the MS restarts the transmitter. The MS sets a fade timer for the forward call channel. The fade timer is activated when the MS first operates the terminal transmitter in a call channel initialization sub-state of the terminal control state on the call channel. The fade timer is reset for N (N is a natural number) seconds upon receiving the M (M is a natural number) good frames in succession in a forward channel. If the fade timer expires, the MS stops the transmitter and declares a call failure.

When a call failure occurs in this way, the MS notifies the terminal user of waiting for reconnection (step 304 in FIG. 3), and the BS proceeds with a call release procedure (step 404 in FIG. 4). The MS may notify the terminal user of waiting for reconnection by using a method of flashing a terminal LED (Light Emission Diode) to emit light, displaying a message on the terminal display window, or generating a specific tone. . The terminal user recognizes when the call automatic reconnection due to the call failure is provided through the above methods.

Meanwhile, the BS notifies the MSC of the call failure as it detects the occurrence of the call failure. The BS may notify the MSC of the call failure by using an existing message or using a new message. In the method of using the existing usage message, there is a method of notifying a call failure by combining element values in the existing message without changing the existing message, and a method of notifying a call failure by defining a new element and adding the same in the existing message.

If the BS detects a call failure, the BS notifies the MSC using the signal used in the call release procedure. The procedure of the release procedure performed in step 404 of FIG. 4 will be described with reference to FIG. 2.

As the BS detects the occurrence of a call failure, the BS notifies the MSC of the failure using the existing release signal. That is, the BS detecting the occurrence of a call failure transmits a release signal including the failure notification information to the MSC. In FIG. 2, the release signal including the failure notification information is indicated by a "Clear Request (DROP)" or "Release (DROP)" signal. If the failure notification information included in the release signal is, for example, "1 (= DROP)", the release signal may be defined as a release signal due to a call failure, and if "0 (= NORMAL)", the release signal may be defined as a normal release signal. Can be.

When the MSC is in a call service (in a call) state (step 500 of FIG. 5) and a release signal transmitted from the BS, that is, a "Clear Request" or "Release" signal is received (step 502 of FIG. 5), The failure notification information included in the release signal is used to determine whether or not the connection status is reconnected (step 504 of FIG. 5). For example, the MSC recognizes the reconnection situation when the failure notification information is "1 (= DROP)".

Specific methods for including or adding the failure notification information to the existing "Clear Request" or "Release" signal are as follows. In the first method, fault notification among the message types that constitute the "Clear Request" or "Release" signal format specified in IS-634, that is, the values specified in the "Cause" information element among Cause, Circuit Identity, and Code Extension. Values that can be used as variables can be used to determine if the BS is in a failure notification situation. Examples of values defined in the "Cause" information element that can be used as fault notification variables include "Up link Quality (Cause: 0x02), Up link Strength (Cause: 0x03), MS not equip (0x20), BS" not equip (0x25), etc. In the second method, the MSC determines whether the BS reports a failure notification by adding a failure notification information element to the "Clear Request" or "Release" signal format specified by IS-634. You may.

Another method for fault notification is to define and use a new message for fault notification. When the BS detects a call failure, it will send a defined new message to the MSC. The defined new message format is implemented in the same way as the "Release Request" signal or the "Release Request" signal.

In the determination of step 504 of FIG. 5, if it is not in the reconnection state, call release (step 520 of FIG. 5) is performed. However, in the reconnection situation, the MSC connects the announcement to notify the other subscriber that it is waiting for reconnection (step 506 of FIG. 5). The announcement may be provided as a general voice message, music, tone, mute if the other subscriber is a telephone subscriber, and provided in the form of null data if the other subscriber is a data subscriber or a service providing device. Can be.

The MSC drives the timer with the timer value T-Val1 after connecting the announcement to the other subscriber (step 508 of FIG. 5). The T-Val1 is a timer value for determining whether the BS, which receives the location registration from the MS after receiving the release signal according to the failure call, transmits a location update request signal within the corresponding time. The T-Val1 time is set from several seconds to several hundred seconds. The timer value T-Val1 is registered as initialization data and may be changed by an operator according to a system operation state and characteristics of a subscriber. While the T-Val1 timer is running, the general recall procedures (Clear Command, Clear Complete, SCCP RLSD, SCCP RLC) as shown in FIG. 2 defined in IS-634 are performed between the BS and the MSC ( Step 404 of FIG. 4, step 510 of FIG. 5).

Meanwhile, as shown in FIG. 2, the MS notifies the user of waiting for reconnection as a call failure is detected (step 304 of FIG. 3), and performs terminal initialization (step 308 of FIG. 3). In more detail with reference to FIG. 3, when a call failure is detected, the user is notified of reconnection waiting (step 304 of FIG. 3), and a timer having a timer value of T-Val2 is driven. The timer value T-Val2 is a timer value set to determine whether a page message is transmitted from the BS within a preset time after detecting a call failure. The timer value T-Val2 is in the unit of several tens of seconds, preferably about 30 seconds. After driving the timer whose timer value is T-Val2, the MS performs terminal initialization (step 308 of FIG. 3). In the terminal initialization process, system re-aquisition is performed and is maintained in the MS idle state.

In this state, only the radio channel in which the call failure occurs, for example, the radio service channel between the MS and the base station, is released, but the remaining existing service channels, such as the BS and the MSC, and / or the MSC and the other MSCs, the MSC and the other subscribers, It stays the same.

When the call failure phenomenon is resolved due to the position movement of the MS which performs the terminal initialization, the MS transmits a "Registration Message" signal, which is a location registration request message, to the BS (step 310 of FIG. 3). The BS determines whether the "Registration Message" signal, which is the location registration request message, is received (step 406 of FIG. 4), and if so, transmits a "Location Updating Request" signal indicating a location update request to the MSC in response. (Step 408 of FIG. 4).

The MSC determines whether a Location Updating Request is received before the timer value T-Val1 expires (step 512 of FIG. 5). If it is not received, the reconnection failure announcement is connected to the other subscriber (step 528), and then the call is released (step 530).

If the location update request message (Location Updating Request) is received before the timer value T-Val1 expires in the determination of step 512 of FIG. 5, the MSC determines whether the location requesting MS is its subscriber and if it is its subscriber. A location registration request is made with its own VLR (step 514 of FIG. 5). That is, the MSC sends a "Registration Notification" signal to its VLR.

Here, an example of a case where the MS requested by the MSC for location registration is its subscriber will be described with reference to FIG. 2. If a call failure occurred in the region 10, 12, 14 in Figure 2, the MS becomes its subscriber in VLR 72a in MSC0 70a.

However, if a call failure occurs in region 16, and the MS has moved from the region of MSC1 70b to the region of MSC0 70a, the MS is not its subscriber from the perspective of MSC0 70a.

A method for reconnecting a call when the MS requesting location registration to the MSC is its subscriber will be described immediately with reference to FIG. 2, and a method for reconnecting a call when the MS requesting location registration to the MSC is not its subscriber. Will be described later with reference to FIGS. 8A and 8B.

If the MS requesting a location registration is its subscriber, the MSC makes a location registration request with its VLR (step 514 of FIG. 5). That is, the MSC sends a "Registration Notification" signal to its VLR.

The VLR receives a registration notification sent by the MSC (step 700 of FIG. 7), and determines whether information of the corresponding MS registered therein is in a call service (calling) state (step 702). . If the information of the corresponding MS is in call service (calling) state in 702 of FIG. 7, since the location registration request of the MSC requires re-connection of an existing call, the VLR indicates a location registration request response message (Registration Notifi.Ack). After resetting the flag (Reconnection flag = "1") in the set and transmits to the MSC (step 704 of FIG. 7). If the information of the corresponding MS is not in the call service (calling) state in step 702 of FIG. 7, the VLR resets the reconnection flag in the location registration request response message (Reconnection flag = "0). ") And then the MSC (step 706 of FIG. 7).

FIG. 11 shows a structure in which a reconnection flag is added to a location registration request response message defined in IS-41, that is, "Registration Noti. Ack." Referring to the format configuration shown in FIG. 11, it can be seen that a 1-bit reconnection flag is included in a spare. The Reconnection Flag is set to, for example, "1 (= DCR; Drop Call Reconnection)" when the failure call is informed that the call can be reconnected after successful location registration.

The MSC determines whether a location registration request response message (Registration Noti. Ack (DCR)) having a reconnection flag (Reconnection flag = "1") is received from the VLR (step 516 of FIG. 5), and the BS is received. The location registration acceptance response (step 518 of FIG. 5). That is, it transmits a "Location Update Accepte" signal to the BS.

The BS determines whether a "Location Update Accepte" signal, which is a location registration acceptance response of the MSC, is received (step 410 of FIG. 4), and transmits a location registration acceptance response message to the MS (step 412 of FIG. 4). That is, it transmits a "Registration Acception Order" signal to the MS. Accordingly, the MS receives a location registration acceptance response, that is, a "Registration Acception Order" signal (step 312 of FIG. 3).

The MSC sends a SCCP RLSD signal after sending a location registration accept response to the BS, that is, a "Location Update Accepte" signal, and in response, the BS sends the SCCP RLC to the MSC.

Thereafter, when the MSC performs the paging request for failing call reconnection, that is, the MSC transmits a “paging request” to the BS (step 520 of FIG. 5). When the paging request, the MSC may request reconnection paging only to the corresponding base station, and may also request reconnection paging to neighbor base stations including the corresponding base station. It is more desirable to request paging for neighboring base stations, including the busy base station, than to request paging only for a busy base station.

The paging area for reconnection according to an embodiment of the present invention will be described in more detail below. The paging area for reconnection can be determined by the internal data of the MSC. Paging for reconnection may attempt paging only to a corresponding cell where a called subscriber (terminal) is located, and may attempt to paging several adjacent cells into one paging area. In addition, paging may be attempted to a broad area including all cells controlled by the MSC. In the present specification, paging to only the corresponding cell is defined as "cell paging", paging several adjacent cells to a single paging area is defined as "PAI paging", and the MSC includes all the cells that are in charge of the broadcast ( paging to broad) is defined as "broad paging".

Cell paging is a commonly used method for primary paging attempts. PAI paging is used to increase the paging success rate than the cell paging of one cell, and is preferably used as a method of secondary paging or primary paging after cell paging during primary paging. Broad paging is used when the location information of the MS is unknown or when the primary paging fails to increase the probability of paging success by widening the paging area.

Meanwhile, the BS determines whether a paging request is received (step 414 of FIG. 4), and transmits a page message to the MS as shown in FIG. 2 when the paging request is received (step 416 of FIG. 4). . Figure 2 shows an example of sending a page message only once. However, when the BS tries to reconnect paging, it is desirable to perform a plurality of times. It is preferable to try cell paging at the first paging, PAI paging at the second paging, and then PAI paging to a larger area than the PAI area at the second paging. And, if paging is not known when the location information of the MS is unknown. Therefore, the paging success rate will be increased if the system operator sets up a suitable paging area for reconnection paging according to the environment and paging order.

FIG. 15 is a diagram illustrating an example in which a corresponding paging area and a corresponding cell are configured as one paging area during paging for reconnection. In FIG. 15, C_1, ... C_18 means a cell. When the incoming location information is cell C_1, the MSC requesting reconnection paging does not require paging only to cell C_1, but C_1, C_2, all cells belonging to the area PAI_1 composed of the cell C_1 and its neighbor cells. Require primary paging with C_3, C_4 and C_5. Each cell belonging to the area PAI_1 may or may not belong to the same MSC. If there is no response to the primary paging, paging may be requested in an area wider than the area PAI_1 in the primary paging. That is, the secondary paging area may require PAI_2 or broadcast paging including all cells in the MSC.

In addition, if the MSC to which the cell to request reconnection paging belongs is different from the MSC to which the cell and the neighboring cells belong to each other, to request reconnection paging to all neighbor cells, paging to the other MSC from the calling party must be requested. Intersystem Page).

15 is a diagram illustrating an example of using an intersystem page according to an embodiment of the present invention. For example, as shown in FIG. 15, when the PAI_1 region is configured, when the information of the cell to which the originating MSC1 requests an incoming call is C_3, when the retry paging is requested to a cell adjacent to C3, cells belonging to the PAI_1 region, that is, C_2 Reconnect paging should be requested as, C_3, C_4, C_5. Among these cells, C_2 and C_3 may request paging directly from MSC1, but for paging to C_4 and C_5, the originating MSC1 uses inter-system page 2 to request paging from MSC2 (ie, C_4, Delivers the message containing the ID of C_5 to MSC2. The MSC2 receives the paging attempt at C_4 and C_5. If the MSC2 receives a response from the BS, the MSC2 transmits a response to the intersystem page 2 to the MSC1. In the case of subscribers located at the MSC and MSC boundaries, intersystem Page 2 can increase the paging success rate.

On the other hand, after receiving the location registration acceptance response message from the BS, that is, the "Registration Acception Order" signal, the MS determines whether a page message from the BS is received within the T-Val2 time (step 316 of FIG. 3). If the page message is not received within the time T-Val2 in step 316 of FIG. 3, the notification indicating that the page message is waiting for reconnection is canceled (step 318 of FIG. 3), and then the idle state is entered (320 of FIG. 3). step). If a page message is received in step 316 of FIG. 3, the MS releases the T-Val2 timer (step 322), and then sets a call path using the existing paging method specified in IS-634 (step 324). To step 334).

2 is a conventional paging procedure defined by IS-634, and it should be understood that the signals in the block 200 are characteristically shown for better understanding in the description of embodiments of the present invention. . 6 shows a flowchart of performing a call connection procedure using the existing paging method defined in IS-634. The call connection flowchart of FIG. 6 is an actual call connection procedure performed in block 200 of FIG.

If the MS receives a page message (Page Message), the operation of reconnecting the call in the MS, BS, MSC as follows. 2 and 6, when a page message is received, the MS transmits a page response message to the BS (step c of FIG. 6 and step 324 of FIG. 3). When the BS receives a page response message (step C in FIG. 6 and step 418 in FIG. 4), the BS transmits a "Complete L3 Info: Paging Response" signal indicating the paging success to the MSC (step d in FIG. 6). , Step 420 of FIG. 4). The MSC determines whether paging is successful according to whether the "Complete L3 Info: Paging Response" signal is received (step 522 of FIG. 5), and when the "Complete L3 Info: Paging Response" signal is received, resets the MSC call path. (Step d to u of FIG. 6, step 524 of FIG. 5), the announcement broadcast waiting for reconnection connected to the counterpart subscriber is released (step 526). On the other hand, if the “Complete L3 Info: Paging Response” signal is not received in step 522 of FIG. 5, an announcement broadcast to notify the other subscriber of a reconnection failure (step 528 of FIG. 5) is performed, and then call release is performed (FIG. 5). Step 530).

When the page response message is received (step c in FIG. 6 and step 418 in FIG. 4), the BS transmits a "Complete L3 Info: Paging Response" signal to the MSC, indicating paging success (FIG. The paging procedure is subsequently performed using the existing paging method (step d of FIG. 6) (step d to u of FIG. 6 and step 420 of FIG. 4) to make a call service (call) state (step 422 of FIG. 4).

After transmitting the page response message (Page Response Message) to the BS in step 324 of FIG. 3, the MS performs a paging procedure using the existing paging method to become a call service state. In more detail, after transmitting a page response message (Page Response Message) to the BS, it is determined whether "Alert with Info" is received (step 326 of FIG. 3), and when received, informing that the subscriber is waiting for reconnection. Release the notification. Thereafter, the terminal generates a ring (step 330 of FIG. 3), and when the terminal user answers (step 332 of FIG. 3), the terminal enters a call service (call) state (step 334).

Next, a method of reconnecting a call when the MS requesting location registration to the MSC is not its subscriber will be described with reference to FIGS. 8A to 8C. 8A to 8C are flowcharts of a mobile terminal subscriber performing a call automatic reconnection after moving to a current MSC service area after a call failure occurs in a previous MSC service area.

8A and 8B, when the MS requesting a location registration to the current MSC is not its subscriber, the current MSC makes a location registration request to its VLR (ie, the current VLR). That is, the current MSC transmits a "Registration Notification" signal to its VLR (current VLR). Accordingly, the current VLR determines whether there is information of the corresponding MS according to a registration notification transmitted by the current MSC. Since the present VLR is not a subscriber, there is no information of the corresponding MS. As a result, the current VLR makes a registration notification to the HLR, and the HLR makes a registration cancellation command to the previous VLR registered with the MS.

FIG. 12 shows a structure in which "MSD ID" and "Location Area ID" are added to a location registration deletion command message prescribed by IS-41, that is, an existing "Registration Cancellation" message. The "MSC ID" and "Location Area ID" received by the location registration delete command are used later for intersystem paging.

Upon receiving the registration cancellation command, the previous MSC determines whether the information of the corresponding MS is in a busy state. If the normal call release was performed (when the call was terminated by the intention of the other subscriber or the terminal user), the MSC deletes the information of the MS registered in its VLR according to the HLR's registration deletion command, and then registers the HLR. Respond with success to the delete command. However, when a call failure occurs, the information of the corresponding MS registered in the VLR is kept in a busy state.

Therefore, if the information of the MS is not busy, the VLR will delete the information of the MS and then perform normal operation. FIG. 8C shows a flowchart of a general operation performed when the information of the corresponding MS is not in a busy state. More specifically, referring to FIG. 8C, the previous VLR deletes the information of the corresponding MS and transmits the registration deletion command result response to the HLR as success. That is, the message "Registration Cancellation Return Message (success)" is transmitted to the HLR. In response, the HLR sends a "Registration Notofication Return Result" signal to the current VLR, which sends it to the current MSC. The current MSC responds with a location registration accept response to the BS. That is, it transmits a "Location Update Accept" signal to the BS. When the BS receives a "Location Update Accept" signal, which is the location registration acceptance response of the MSC, the BS transmits a "Registration Accepted Order" signal, which is a location registration acceptance response message, to the MS.

8B, however, if the information of the corresponding MS is in a busy state, the previous VLR transmits the registration deletion command result response to the HLR without failing to delete the information of the MS. That is, as shown in Fig. 8B, it is transmitted as a "Registration Cancellation Return Result" signal. The previous VLR also forwards a Registration Reconnection message to its MSC (ie, the previous MSC).

13 illustrates a structure of a registration reconnection message according to an embodiment of the present invention. The parameter of the registration reconnection message includes an electric serial number (ESN), a mobile identification number (MIN), an MSC ID, a location area ID, and the like, and is used for an intersystem page. The ESN is the terminal's serial number, the MIN is the subscriber's number, the MSC ID is the MSC's ID, and the Location Area ID is the area to be paged.

The HLR, which has received a registration cancellation command result response message, that is, a "Registration Cancellation Return Result" signal from the previous VLR, transmits a "Registration Notofication Return Result" signal to the current VLR. Send to current MSC. The current MSC responds with a location rejection response to the BS, i.e. sends a "Location Update Reject" signal to the BS. When the BS receives a "Location Update Reject" signal of the location registration rejection response of the MSC, the BS transmits a "Registration Reject Order" signal of the location registration rejection response message to the MS.

On the other hand, the previous MSC that receives the Registration Reconnection message from the previous VLR will use the Location Area ID of the MSC ID listed in the Registration Reconnection message. That is, the previous MSC transmits the message "InterSystem Page2" to the current MSC, and the current MSC receives the paging attempt to the MS through the BS. That is, the MSC transmits a "Paging Request" signal to the BS, and the BS transmits a "Page Message" signal to the MS in response.

When the MS sends a "Page Response Message" signal in response to the BS, the BS sends a "Complete L3 Info: Paging Response" signal to the current MSC in response. The current MSC transmits the "InterSystem Page2 Return Result" signal to the previous MSC in response to the BS "Complete L3 Info: Paging Response" signal.

Since the subsequent call reconnection procedure is the same as the operation description of the procedures according to FIG. 2 described above, the description thereof is omitted.

9 and 10 illustrate a transition state of a call processing state according to the prior art and the embodiment of the present invention. In the prior art, as shown in FIG. 9, when a call is released from a busy state or a disconnection occurs continuously for a predetermined time or more, for example, 5 seconds or more, the state immediately transitions to an idle state. In contrast, in the exemplary embodiment of the present invention, as shown in FIG. 10, when a call connection failure occurs for a first time, for example, several seconds (preferably one or two seconds) in the call service state, the mobile station transitions to a waiting state waiting for a reconnection request. If there is a request for reconnection by the location registration method, the paging procedure is performed to transition back to the call state. However, even in the standby state, if the call disconnection continues for a second time, for example, several tens of seconds (preferably between 30 seconds and 60 seconds), the state transitions to the idle state. In addition, even in the embodiment of the present invention, if there is a release request in the call service or waiting state, the state immediately transitions to the idle state.

In the above description of the present invention, specific embodiments have been described, but various modifications can be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be defined by the equivalent of claims and claims.

As described above, according to the present invention, when a call failure occurs in a public mobile communication network, the call is automatically reconnected by the terminal location registration method, and the call is released by a temporary disconnection condition such as an elevator or a tunnel. Eliminate the inconvenience. As a result, mobile subscribers can be relieved of anxiety about call disturbances and secure call quality for public mobile communication networks.

Claims (7)

In a mobile communication system having a plurality of base stations and a plurality of mobile switching stations, one of the plurality of base stations connected to a subscriber's mobile terminal and at least one of the plurality of mobile switching stations connected to the connected base station is selected. In the method of re-connecting the service between the subscriber's mobile terminal and the subscriber's terminal in case of service failure during the service with the subscriber's terminal, When the location error request message from the mobile station of the subscriber is received by the subscriber in the service failure to one of a plurality of base stations and a mobile switching station connected thereto, the mobile switching station finding a location registration device that has registered the previous location of the mobile station; Determining whether the information of the mobile terminal registered in the found location registration device is in service; And when the information of the mobile terminal is in service, the mobile switching station attempts to reconnect to the mobile terminal and resumes the service between the subscriber's mobile terminal and the subscriber's terminal. The method of claim 1, wherein when the service failure occurs for a predetermined first period or more, the mobile switching station providing the service further has a process of informing the subscriber's terminal that it is waiting to resume service. The method of claim 1, wherein the mobile terminal of the subscriber further informs the mobile terminal subscriber that it is waiting to resume service when the service failure occurs over a predetermined first period. The method of claim 1, wherein when the subscriber's mobile terminal and the subscriber's terminal fail to resume service, the mobile switching station providing the service further has a process of providing the subscriber's terminal with a service resume failure message. How to. The process of claim 1, wherein the finding of the location registration device is performed. Transmitting the location registration request to the home location registration device when the mobile switching center requests the location registration to its temporary location register; The home location registration device receiving the location registration request comprises the step of requesting registration deletion to a temporary location register corresponding to the previous location of the subscriber's mobile terminal. The method of claim 5, wherein the determining of whether the service is in the service state comprises: When the temporary location register corresponding to the previous location of the subscriber's mobile terminal receives the cancellation request, if the information of the mobile terminal is in service, a message indicating that the registration deletion has failed is performed. Delivering to the mobile switching center through; If the information of the mobile terminal is not in the service state, the location information of the mobile terminal registered in the temporary location register corresponding to the previous location of the mobile terminal of the subscriber is deleted and a message of successful registration deletion deletes the home location registration device and the self. Delivering to the mobile switching center through a temporary location register of the mobile station. In a mobile communication system having a plurality of base stations and a plurality of mobile switching stations, one of the plurality of base stations connected to a subscriber's mobile terminal and at least one of the plurality of mobile switching stations connected to the connected base station is selected. In the method of re-connecting the service between the subscriber's mobile terminal and the subscriber's terminal in case of service failure during the service with the subscriber's terminal, Determining whether a service failure occurs in the service between the subscriber's mobile terminal and the subscriber's terminal for a predetermined first period or more; If the service failure occurs more than the first predetermined period of time to provide a notification message to inform the subscriber's mobile terminal and the subscriber's terminal waiting to resume service, and initializing the mobile terminal; When the location registration request message is transmitted from the mobile terminal which is in the service enabled state to the mobile switching center connected to the base station through a base station wirelessly connected with the mobile terminal, the mobile switching station finding a location registration device that has registered the previous location of the mobile terminal; and, Determining whether the information of the mobile terminal registered in the found temporary location registration device is in service; And when the information of the mobile terminal is in service, the mobile switching station attempts paging to resume the service between the subscriber's mobile terminal and the subscriber's terminal.