JP2963689B1 - Mobile communication system and mobile terminal - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To reduce a probability that a communication of a mobile terminal is forcibly disconnected due to a shortage of an available transmission band in a destination wireless zone at the time of handoff of the mobile terminal. SOLUTION: A mobile switching center S for setting and controlling a communication line.
W has means for grasping the transmission band of the free communication line in the wireless zones ZN1 to ZNi managed by the subordinate wireless base stations BS1 to BSi. For example, from mobile terminal MS3 to ZN
When there is a handoff request to the mobile terminal MS3, it is determined whether or not there is an available communication line in the destination wireless zone ZN2 that is equal to or greater than the transmission band required by the mobile terminal MS3. Notifies that there is no free line. The mobile terminal MS3 notifies the subscriber of the arrival of the notification of no available line by displaying or by sound. The subscriber can prevent the communication from being forcibly disconnected by stopping the movement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a mobile communication system such as an automobile telephone system and a portable telephone system.

[0002]

2. Description of the Related Art Conventionally, in a mobile communication system such as an automobile telephone system and a portable telephone system, when a mobile terminal moves in a wireless zone during communication, a handoff for switching to a communication line of a destination wireless zone (during communication). Channel switching) is performed, but if there is no free communication line not used for communication in the destination wireless zone, and if the mobile device is moved as it is, the communication is forcibly disconnected in the destination wireless zone. There was a problem that would be done.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to reduce the frequency of forcibly disconnecting a communication because a mobile terminal cannot secure a wireless channel in a destination wireless zone during a handoff during communication. I have.

[0004]

In order to achieve the above object, a mobile communication system according to the present invention comprises a mobile switching center for controlling the setting of a communication line and a radio base station for managing a radio zone.
In the mobile communication system, the mobile switching center comprises: a mobile terminal that, when a mobile terminal moves in a wireless zone during communication, performs a handoff for switching to a communication line of a destination wireless zone to continue communication. has means for grasping the transmission band of the radio zone free communication line to manage the overall region of the wireless base station, when there is a handoff request from a mobile terminal, that moves to its destination radio zone determining whether the terminal is idle communication channel of the transmission band to be necessary, if there are no free communication line or the transmission band required, the free communication of required transmission bandwidth to the mobile terminal line is configured to deliver an empty-out without line notification that notifies that no, the mobile terminal informs the subscriber that from the mobile switching center has arrived the absence idle line notification And means that, without notice the free line
After a certain period of time has passed since the
Compare the field strength of the zone with the field strength of the neighboring wireless zone.
And the difference in the electric field strength reaches the level at which handoff is required.
Handoff to the mobile switching center when
Means for outputting a request, and receiving the idle line absence notification.
Switch to the destination wireless zone after
Means for notifying the subscriber of the fact . As a result, when the notification indicating that there is no free line arrives, communication can be continued without moving by the will of the subscriber. In addition, receiving a notification that there is no free line,
Subscriber who did not move to continue, starts moving again
can do.

[0005]

In addition , the mobile switching center, for a notified mobile terminal that has already sent the no-line-free notification, sends the notification transmission time, the required transmission band, and Hold data for managing information such as the wireless zone number in the, when detecting a change in the idle communication line in the wireless zone of the wireless base station under the control, refer to the data for the corresponding wireless zone, Based on the required transmission band in the data, it is determined whether the notified mobile terminal that can use the transmission band of the free communication line exists, and In this case, the wireless zone is notified that the communication line is free, and is switched to the destination wireless zone. As a result, the subscriber who did not move to continue communication by the notification of no available line,
The movement can be started again.

[0007] In addition, the mobile switching center, when there is a handoff request from the mobile terminal, when there is no vacant communication channel of the transmission band of the mobile terminal is required for the destination radio zone, the mobile A search is made in the data for managing the notified mobile terminal as to whether there is a notified mobile terminal to which the terminal is currently moving to the wireless zone with which communication is currently performed and to which the notification of no available line has already been transmitted, and transmission notified mobile terminal when present, plus the necessary transmission bandwidth of the mobile terminal that originated the radio zone currently communicating transmission band and said handoff requests for free communication line of the mobile terminal having issued the handoff request The bandwidth corresponds to the above
That is a notification already seen mobile terminals of the necessary transmission bandwidth or more, and,
Of a mobile terminal transmission bandwidth plus the necessary transmission bandwidth notified mobile terminal transmission band and to the corresponding free communication line current radio zone in communication Notified viewed mobile terminals has issued the handoff request the appropriate required when it was confirmed that the transmission band or is switched to the both radio zones <br/> destination notified that vacant communication line to each destination radio zone to the mobile terminal, in the case other than the above,
The idle time notifying the mobile terminal that has issued the handoff request that there is no idle communication line of a required transmission band.
A lineless notification is sent out, and the data for managing the notified mobile terminal is transmitted to the mobile terminal that has issued the handoff request.
The information is registered. As a result, the stopped mobile terminal can be moved to the destination even if there is no free band in the destination wireless zone that is higher than the transmission band required by the mobile terminal that has stopped moving.

[0008] Furthermore, the mobile terminal, the field strength of the electric field strength and the neighboring radio zone of the radio zone currently in communication
Compared bets, difference of the field strength to the handoff request
It should be equal to or less than a larger predetermined level than
When detecting, the mobile switching center has means for sending a handoff notice to the mobile switching center via a radio base station that manages the currently communicating wireless zone, the mobile switching center,
When the handoff notice is received, the transmission band of the free communication line in the neighboring wireless zone is checked, and if there is no free communication line of the required transmission band requested by the mobile terminal, the communication is performed via the wireless base station. the notifying that there is no vacant communication line to the mobile terminal sends a advance notice, the mobile terminal hands stage you notify the subscriber said that the advance notice was received from the mobile switching center It has. As a result, a warning can be issued earlier, so that even in the case of a high-speed mobile terminal or a small wireless zone configuration, a sudden stop at the time of handoff does not need to be performed.

Further, the mobile terminal of the present invention has a mobile switching center for controlling the setting of a communication line and a radio base station for managing a radio zone , and when the mobile terminal moves through the radio zone during communication, a mobile terminal used in a mobile communication system configured to continue the communication by performing a handoff to switch to the destination radio zone communication line, when performing a handoff request, to the destination radio zone receiving a no idle channel notification is notified from the mobile switching center when there is no free communication lines of the transmission band that require
When taking only the hand <br/> stage you notify the subscriber that the predetermined time after receiving the notification without the idle line
After the elapse, the electric field strength of the
Compare the electric field strength of the wireless zone, and
When the level at which the
Means for outputting a handoff request to a mobile switching center;
Destination wireless zone after receiving notification of no available line
Notify subscribers when switched to
And means for performing the above. Furthermore, the electric field strength of the electric field strength and the neighboring radio zone of the radio zone currently in communication
Comparing the degrees, the difference in the electric field intensity to the handoff request
It should be equal to or less than a larger predetermined level than
Can and has been detected, to a means for transmitting a handoff advance notice to the mobile switching center via a wireless base station managing the radio zone currently communicating, require the neighboring radio zone
When receiving the advance notice of the notified from the mobile switching center when there is no vacant communication channel of the transmission band area that is one and a means for notifying the subscriber that the.

[0010]

FIG. 1 is a diagram showing an example of a configuration of a mobile communication network in which a mobile communication system according to the present invention is realized. In this figure, SW is a mobile switching center, and as shown, holds three types of information: notified mobile terminal information 10, wireless zone information 20, and communicating mobile terminal information 30. The information will be described later.
.., BSi are radio base station groups under the mobile switching center SW, ZN1, ZN2,.
ZNi is the radio base station BS1, BS2,..., BS
i, the wireless zone managed by each, MS1, MS2, M
S3, MS4, MS5, MS6 ... are mobile terminals.

FIG. 2 is a diagram showing an example of the notified mobile terminal information 10. This notified mobile terminal information 10
Is information that manages a mobile terminal that has been notified that there is not a sufficient transmission band in the destination wireless zone (hereinafter, referred to as a “notified mobile terminal”).
0, the mobile terminal number 510, the required transmission band 520, the notification signal transmission time 530, and the communicating wireless zone number 540. These pieces of information are set when the mobile terminal is notified that there is not enough transmission band in the movement destination wireless zone and receives an acceptance response to the notification, and has a transmission band sufficient for communication as described later. Is deleted when the user is notified that is available. As will be described later, the notified mobile terminal information 10 is not used in the first embodiment of the present invention.

Here, the destination wireless zone number 500 is a number indicating the wireless zone to which the mobile terminal having the mobile terminal number 510 is going to move, the mobile terminal number 510 is a number for identifying the notified mobile terminal, and Transmission band 5
20 is the transmission band required by the mobile terminal of mobile terminal number 510, notification signal transmission time 530 is the time at which the notification signal was transmitted to the mobile terminal of mobile terminal number 510, and wireless zone number 540 during communication is the movement of mobile terminal number 510. The number of the wireless zone in which the terminal is currently staying and communicating. In addition,
FIG. 2 shows an example in which minutes and seconds are stored as the notification signal transmission time 530. However, the present invention is not limited to this. For example, hours, minutes, and seconds may be stored, or millimeters and seconds may be stored. You may make it memorize | store in a unit of second.

FIG. 3 is a diagram showing an example of the wireless zone information 20. This wireless zone information 20 is
It is information for managing a wireless zone managed by the wireless base stations BS1 to BSi controlled by W. For example, FIG.
As shown in FIG. 7, data such as the wireless zone number 600 and the free transmission band 610 are included. Here, the wireless zone number 600 is a number for identifying a wireless zone, and the vacant transmission band 610 is data indicating a transmission band of a vacant line in the wireless zone of the wireless zone number 600.
These pieces of information are updated when a change occurs in the free transmission band of the wireless zone due to the start, end, and handoff of communication of the mobile terminal.

FIG. 4 is a diagram showing an example of the mobile terminal information 30 during communication. The communicating mobile terminal information 30 is information for managing the communicating mobile terminal. For example, as shown in FIG.
It is composed of data such as 0. Each mobile terminal can apply for a required transmission band at the start of communication and start communication when accepted by the network. When the communication starts, the communicating mobile terminal information 30 is set, and when the communication ends, it is deleted. Here, the mobile terminal number 700 is a number for identifying a mobile terminal in communication. The required transmission band 71
0 is a transmission band required by the mobile terminal having the mobile terminal number 700, and a value declared by the mobile terminal to the network at the start of communication is set.

Hereinafter, the mobile communication system of the present invention will be described with reference to a mobile terminal MS3 (FIG. 1) moving while communicating. First, the operation of the mobile communication system according to the first exemplary embodiment of the present invention will be described in detail with reference to the flowchart of FIG. As shown in FIG.
It is assumed that the mobile terminal MS3 is communicating within the wireless zone ZN1 managed by the base station BS1 and is moving in the direction of the arrow. The mobile terminal MS3 performs step S10 in FIG.
, The electric field strength from the wireless zone ZN1 with which communication is currently being performed and the neighboring wireless zone is observed. Then, it is determined whether or not the electric field strength of the neighboring wireless zone has become larger than the electric field strength of the current wireless zone ZN1, that is, whether or not the mobile station has entered the handoff area. Proceed to
A handoff request notification signal including data for identifying a nearby wireless zone (a destination wireless zone) having an increased electric field strength is sent to the mobile switching center SW via the wireless base station BS1 managing the current wireless zone. Send out. Here, this nearby wireless zone is assumed to be ZN2.

Upon receiving the handoff request notification signal in step S40, the mobile switching center SW firstly stores the wireless zone information 20 (FIG. 3) and the communicating mobile terminal information 30.
Referring to (FIG. 4), the available transmission band of the communication line and the required transmission band of the mobile terminal MS3 in the destination wireless zone ZN2 specified in the handoff request notification signal are grasped. Then, it is checked whether the free transmission band 610 of the destination wireless zone ZN2 is larger than the required transmission band 710 of the mobile terminal MS3, and whether a communication line of the transmission band required by the mobile terminal MS3 can be secured. As a result, if the required transmission band can be secured, the handoff process is started as it is. On the other hand, if it cannot be secured, step S
Go to 50. In the case of the example shown in FIGS. 3 and 4, the free transmission band 610 of the wireless zone ZN2 is 1.5 Mbps.
And the required transmission band 710 of the mobile terminal MS3 is 2.5
Mbps, the process proceeds to step S50.

Since it is difficult for the mobile switching center SW to secure an empty communication line in the destination wireless zone ZN2 in step S50, the mobile switching center SW sends the radio base station BS1 to the mobile terminal MS3 that has issued the handoff request. A notification signal for notifying that there is no vacancy in the transmission band of the communication line in the wireless zone of the movement destination via is transmitted. This notification signal is transmitted to the mobile terminal MS3 using, for example, a control channel.

When the mobile terminal MS3 receives the notification signal in step S60, it notifies the subscriber that there is no free space in the transmission band of the communication line in the destination wireless zone by using notification means such as display or sound. Notify. This allows
The subscriber can recognize that the communication can be continued in the current wireless zone if the movement is stopped, and determines whether the movement can be stopped. If the movement cannot be stopped and the user moves out of the current wireless zone, the communication is forcibly disconnected.

As described above, when there is no free communication line of a sufficient band in the destination wireless zone, the mobile switching center sends a notification signal to notify the mobile terminal that there is no free communication line, thereby enabling the mobile terminal to perform the mobile communication. The terminal (subscriber) can know that communication cannot be continued when moving in the moving direction. Therefore, the subscriber can continue the communication by stopping the movement.

In the above case , if there is no free line in the destination wireless zone, handoff cannot be performed . Therefore, handoff can be performed after a predetermined time has elapsed by adding the following processing.

The mobile terminal MS3 receiving the notification signal
When a predetermined time has passed since the notification signal was received,
As in step S10, the electric field strengths from the wireless zone ZN1 currently communicating and the neighboring wireless zone are observed again. Then, it is determined whether or not the electric field strength of the neighboring wireless zone remains higher than the electric field strength of the current wireless zone ZN1, that is, whether or not the mobile station is still staying in the handoff area. Similarly, the mobile switching center S via the radio base station BS1 managing the current radio zone.
Send a handoff request notification signal to W. Otherwise, no signal is sent. Note that, in this case as well, the nearby wireless zone is set to ZN2.

The mobile switching center SW that has received the handoff request notification signal performs the following processing as a line check processing, as in step S40. First, the mobile switching center SW refers to the wireless zone information 20 and the communicating mobile terminal information 30, and determines whether the transmission band of the communication line of the neighboring wireless zone ZN2 of the wireless zone ZN1 is available and the mobile terminal M.
The required transmission band of S3 is grasped. And the wireless zone Z
It is checked whether the vacant transmission band 610 of N2 is larger than the required transmission band 710 of the mobile terminal MS3 and a communication line of the required transmission band can be secured. As a result, if the required transmission band can be secured, the handoff process is started as it is.

Then, after the handoff process is completed,
After the connected radio base station is switched to BS2, the mobile terminal MS3 informs the subscriber to that effect. As a result, the subscriber can know that the line has not been disconnected even when the wireless zone is switched and the movement is resumed, and can resume the movement. As described above, in the present invention , the mobile terminal has a function of notifying the subscriber when handoff is performed after receiving the notification signal indicating that there is no idle line. The notification to the subscriber can be made by using various kinds of notification means such as a display unit, an audible display using an acoustic signal or voice, or a display using vibration.

On the other hand, if it is determined that the required transmission band cannot be secured as a result of the line check processing in step S40, the process proceeds to step S50. In this step S50, the mobile switching center SW makes it difficult for the mobile switching center SW to secure an empty communication line in the destination wireless zone as in the case described above. A notification signal for notifying that the transmission band of the communication line is free in the zone is transmitted. And
Upon receiving the notification signal, the mobile terminal MS3 executes the step S10 when the predetermined time has elapsed again,
The above operation is repeated.

As described above, according to the present invention , after receiving a notification signal indicating that there is no available communication line in the destination wireless zone, a request for handoff is made from the mobile terminal at predetermined time intervals. Therefore, it is possible to resume the movement while continuing the communication.

Next, another embodiment of the present invention will be described.
This will be described with reference to the flowchart of FIG. Form of implementation described above, if there is no free line in the destination radio zone, but was made to allow handoff after a predetermined time has elapsed, this
Form of implementation is that as it is possible to handoff when it is empty lines or transmission band that requires the destination radio zone.

As described above, there is no free communication line in the destination wireless zone, and after receiving the free line absence notification signal, the mobile terminal M which stops to continue communication.
In step S3, in step S70, an acceptance response to the notification of no available line is made to the mobile switching center SW via the radio base station BS1. When the mobile switching center SW receives the acceptance response to the notification of no available line from the mobile terminal MS3, the mobile switching center SW performs a notified terminal registration process in step S80. That is, in step S80, the notified mobile terminal information 10 (FIG. 2) includes information on the mobile terminal MS3, the destination wireless zone number 500, the mobile terminal number 510, the required transmission band 520, and the notification signal transmission. Time 53
0 and the data of the communicating wireless zone number 540 are registered. At this time, the destination wireless zone number 50
0, the necessary transmission band 520 is sorted in ascending order, and the notification signal sending time 530 is sorted in ascending order, and the registration is performed.
The search for the notified mobile terminal information 10 can be executed quickly.

The mobile terminal information registered in the notified mobile terminal information 10 is, as described later, provided that there is an available transmission band in the destination wireless zone and handoff can be performed after registration and before handoff can be performed. , Etc., and are deleted when the mobile phone is forcibly disconnected due to being moved to and before the handoff can be performed after the registration and the mobile phone is moved out of the handoff area.

The mobile switching center SW, when there is a change in the number of vacant communication lines in the radio zone of the supervised radio base station, detects this and updates the radio zone information 20 (FIG. 3). (Step S90). For example, assuming that a vacant communication line is created in the wireless zone ZN2 managed by the wireless base station BS2 due to the termination or handoff of the communication of the mobile terminal, this is detected in step S90, and the wireless zone ZN2 in the wireless zone information 20 is detected. Update the available transmission band data 610 for step S10
The process proceeds to the notified terminal process of 0.

In the notified terminal processing step S100, first, in the notified mobile terminal information 10, a wireless zone (in this case, ZN2) in which the number of available communication lines has changed is set as a destination wireless zone. Search for mobile terminals that are located. Then, from the searched mobile terminals, the mobile terminal that performs the notification of the presence of the free line is selected by the following procedure. As an example of the selection procedure, the mobile switching center SW sets the notification signal transmission time 53 in the notified mobile terminal information 10.
Using the 0 as a key, the notified mobile terminals are searched in ascending order of the notification signal transmission time 530, and the wireless zone Z of the wireless zone information 20 is compared with the required transmission band 520 of the notified mobile terminal.
A comparison is made as to whether the free transmission band 610 of the communication line N2 is large, and a mobile terminal having a larger free transmission band 610 is determined. As a result, it is possible to perform handoff by selecting a mobile terminal having a long elapsed time after stopping the movement.

As another example of the selection procedure, the mobile switching center SW searches the notified mobile terminals in the notified mobile terminal information 10 in the order of the required transmission band 520 in ascending order, using the required transmission band 520 as a key. A comparison is made as to whether the free transmission band 610 of the communication line of the wireless zone ZN2 in the zone information 20 is larger than the required transmission band 520 of the mobile terminal, and a mobile terminal having a larger free transmission band 610 is determined. According to this procedure, it is possible to reduce the number of terminals that have stopped moving earlier.

As still another example of the selection procedure, the mobile switching center SW, in the notified mobile terminal information 10, sets the wireless zone information 20 relating to the currently communicating wireless zone set to the communicating wireless zone number 540. The mobile terminals are selected in ascending order of the available transmission band 610 using the available transmission band 610 as a key. Then, a comparison is made as to whether the free transmission band 610 of the communication line in the wireless zone ZN2 is larger than the required transmission band 710 of the mobile terminal, and a mobile terminal having a larger free transmission band 610 is determined. According to this procedure, processing can be performed from a mobile terminal communicating in a wireless zone with a small available transmission band, and traffic in a high-traffic wireless zone can be reduced.

As described above, the free transmission band of the line of the wireless zone ZN2 and the required transmission band of the mobile terminal are grasped, and the mobile terminal whose free transmission band 610 of the wireless zone ZN2 is larger than the required transmission band 520 of the mobile terminal is determined. If it does not exist, this processing does nothing. If there is, the information of the selected mobile terminal is deleted from the notified mobile terminal information 10, and the process proceeds to step S110. Hereinafter, a description will be given assuming that the selected mobile terminal is MS3.

In step S110, the mobile switching center SW
The selected notified mobile terminal notifies the mobile terminal MS3 via the currently connected wireless base station BS1 that there is a free line, and places the mobile terminal MS3 in the wireless zone ZN2.
A handoff for switching to the line is started.

The mobile terminal M that has received the notification that there is a free line.
In step S3, in step S120, the handoff to the wireless zone ZN2 is performed in the same procedure as the conventional handoff. Then, the mobile station notifies the subscriber of the execution of the handoff, as in the case of the movement stop release processing, that is, the case described above. With this, the subscriber can resume the movement. By the above procedure, the mobile terminal that is communicating temporarily stops moving, so that it is possible to continue communication without forcibly disconnecting the communication due to the inability to secure a wireless communication line at the destination.

In the above-described embodiment, the handoff is not performed when there is no available communication line having the required transmission band or more in the destination wireless zone. Still another embodiment of the present invention in which handoff is performed depending on conditions will be described. In this embodiment, when there is a handoff request from the mobile terminal, and there is no free communication line of the transmission band required by the mobile terminal in the destination wireless zone, the destination wireless zone of the mobile terminal, The mobile terminal investigates whether or not there is a notified mobile terminal to which the wireless zone with which the mobile terminal is currently communicating is located by searching the notified mobile terminal information 10. If so, taking into account the required transmission bandwidth of the mobile terminal that has issued the handoff request and the notified mobile terminal and the available transmission bandwidth of both wireless zones, and if possible, handoff of both mobile terminals At the same time.

In FIG. 7, ZN_a and ZN_b are radio zones, MS_a and MS_b are mobile terminals,
a is a mobile terminal that is trying to perform handoff, MS_b is a notified mobile terminal, A is an available transmission band of the radio zone ZN_a, B is a required transmission band of the mobile terminal MS_a, C is a required transmission band of the mobile terminal MS_b, and D is This is a free transmission band of the wireless zone ZN_b. Here, as shown in the figure, the wireless zone ZN_a and the wireless zone ZN_b are adjacent to each other, and the mobile terminal MS_a is currently communicating in the wireless zone ZN_a, as indicated by an arrow in the figure, and
Moving to N_b. On the other hand, mobile terminal MS_
b is currently communicating in the wireless zone ZN_b, and attempts to move to the wireless zone ZN_a,
Since the free transmission band A of the mobile terminal MS_b is smaller than the required transmission band C of the mobile terminal MS_b, handoff cannot be performed, and the mobile terminal MS_b is registered in the notified mobile terminal information 10.

In such a state, step S
The mobile switching center SW, which has received the handoff request notification signal issued from the mobile terminal MS_a in the same manner as the mobile terminal MS_20, searches the notified mobile terminal information 10 and the wireless zone information 20 and performs a handoff.
Regarding a, notification that the currently communicating wireless zone (in this case, ZN_a) is the destination, and the currently communicating wireless zone is the destination wireless zone of the mobile terminal MS_a (in this case, ZN_b). A search is made in the notified mobile terminal information 10 as to whether or not an already-completed mobile terminal exists. In this search method, as in the case of the above-described embodiment, selection is made in the order of the notification signal transmission time 530 of the mobile terminal and in the order of smaller required transmission bandwidth 520. If the notified mobile terminal is not found as a result, the information of the mobile terminal MS_a attempting the handoff is registered in the notified mobile terminal information 10, and the same procedure as in the above-described embodiment is performed. The mobile station MS_a sends an idle line absence notification signal. Here, it is assumed that the mobile terminal MS_b has been searched.

Next, the mobile switching center SW transmits the notified mobile terminal information 10, the wireless zone information 20, and the communication information for the searched notified mobile terminal MS_b and the mobile terminal MS_a attempting the handoff. Referring to the middle mobile terminal information 30, the required transmission band 710 of the mobile terminal MS_a attempting handoff and the required transmission band 520 of the notified mobile terminal MS_b are set as shown in FIG. 7 with the free band 610 of the radio zones ZN_a and ZN_b. Then, it is determined whether or not a relationship of “A + B ≧ C and B ≦ C + D” is satisfied. When the above relationship is established, the mobile terminals MS_a and MS_b can hand off each other. Therefore, a signal for notifying that each mobile terminal has a free line is transmitted, and at the same time, handoff is performed. I do. Thereafter, the same processing as in the case described above is performed. As described above, in this embodiment, even if there is no available transmission band in the target wireless zone that is equal to or greater than the transmission band required by the mobile terminal that has requested handoff or the stopped mobile terminal, And handoff is possible.

Now, as described above, in the present invention,
The mobile terminal is configured to notify the subscriber to that effect when the idle line absence notification signal is notified,
When moving at a high speed or when the wireless zone is small, a warning that there is no free line in the destination wireless zone may be sudden. Therefore, a still further embodiment of the present invention in which a notice of no vacant line is given before such a sudden warning will be described with reference to FIGS. 8 and 9 taking the situation of FIG. 1 as an example. Will be explained.

In step S210 of FIG. 8, the mobile terminal MS
3 observes the electric field strengths from the currently communicating wireless zone ZN1 and neighboring wireless zones. Then, when a difference between the electric field strength of the currently communicating wireless zone and the electric field strength from the neighboring wireless zone is found to be equal to or less than a certain level, a neighboring wireless zone is found, that is, it is determined whether or not the user has entered the adjacent zone detection area in FIG. I do. FIG. 9 shows the wireless zone ZN1.
FIG. 7 is a diagram schematically showing an adjacent zone detection area and a handoff area on a line connecting the centers of ZN2 and ZN2. Upon detecting that the mobile terminal MS3 has entered the adjacent zone detection area in step S210, the mobile terminal MS3 notifies the mobile switching center SW via the wireless base station BS1 managing the current wireless zone to the handoff notice including the nearby wireless zone number. A notification signal is sent (step S220). Here, the nearby wireless zone is ZN2. If necessary, the subscriber may be notified that a handoff notice has been given to the subscriber at this time.

In step S230, the mobile switching center SW that has received the notification that the electric field level of the nearby wireless zone has increased (handoff notice notification signal) first refers to the wireless zone information 20 and the communicating mobile terminal information 30. Then, the transmission band of the communication line of the neighboring wireless zone ZN2 of the wireless zone ZN1 and the required transmission band of the mobile terminal MS3 are grasped. Then, it is checked whether the free transmission band 610 of the wireless zone ZN2 is larger than the required transmission band 710 of the mobile terminal MS3, and whether a communication line of the required transmission band can be secured. As a result, if the necessary transmission band can be secured, nothing is performed, and if not, the process proceeds to step S240.

In step S240, the mobile switching center SW
Since it is difficult to secure a communication line in the destination wireless zone, there is no available line to notify the mobile terminal MS3 via the base station BS1 that there is no available communication band transmission band in the destination wireless zone. Sends a notice signal.

In step 250, when receiving the notice signal indicating that there is no available line, the mobile terminal MS3 sends a notification to the subscriber by using notification means such as display, sound, voice or vibration other than the notification signal. It notifies that there is no free space in the transmission band of the communication line in the destination wireless zone. As a result, the subscriber can take measures such as reducing the moving speed if possible in preparation for stopping the movement. Then, the above-described processing of FIG. 5 and thereafter is executed.

If there is no notification from the mobile switching center SW with respect to the notification of the handoff notice in step S220, the mobile terminal MS3 does nothing. In addition, when the subscriber is notified by a display or a sound that the handoff notice has been notified to the subscriber, the display, the sound, or the vibration is erased to cancel the notification. As described above, according to this embodiment, a preliminary warning can be issued before giving a sudden warning in the case of a mobile terminal having a fast moving speed or a small wireless zone, and a sudden stop by the subscriber can be performed. Can be prevented.

[0046]

As described above, according to the mobile communication system and the mobile terminal of the present invention, the transmission band of the free line required by the mobile terminal moving to the destination wireless zone at the time of handoff is sufficient. If the mobile terminal receives no free line notification from the mobile switching center, the mobile terminal stops moving and can continue communication without switching to the destination wireless zone. It is possible to reduce the probability of being disconnected. Also, the mobile terminal that has stopped moving can restart the movement by making a handoff request after a certain time has elapsed and receiving a notification from the mobile switching center that there is a free line. Further, even if there is no free line with a sufficient transmission band in the destination wireless zone of the mobile terminal to which the handoff request has been made, the mobile switching center communicates with the mobile terminal that has issued the handoff request to the destination wireless zone. If there is a mobile terminal that has stopped moving to the destination wireless zone, and a line with a sufficient transmission band can be secured even if handoff is performed with each other, each mobile terminal is notified that there is a free line, and at the same time, Handoff allows movement. In addition, the subscriber is required to make an abrupt announcement to notify the mobile terminal that the mobile terminal does not have a sufficient free line transmission band in the destination wireless zone in advance that no free line is available, so that the communication can be continued. You do not need to stop for a while.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of a mobile communication system according to the present invention.

FIG. 2 is a diagram illustrating a configuration example of notified mobile terminal information according to the present invention.

FIG. 3 is a diagram illustrating a configuration example of wireless zone information according to the present invention.

FIG. 4 is a diagram showing a configuration example of mobile terminal information during communication in the present invention.

FIG. 5 is a diagram showing an example of the flow of sending an idle line absence notification signal in the present invention.

FIG. 6 is a diagram showing an example of the flow of sending a free line presence notification signal in the present invention.

FIG. 7 is a diagram illustrating an example of a relationship between a free transmission band of a wireless zone and a required transmission band of a mobile terminal according to the present invention.

FIG. 8 is a diagram showing an example of the flow of an idle line no notice notification transmission signal according to the present invention.

FIG. 9 is a diagram showing an example of an adjacent zone detection area in the present invention.

[Explanation of symbols]

 SW mobile switching center BS1 to BSi radio base station ZN1 to ZNi, ZN_a, ZN_b radio zone MS1 to MS8, MS_a, MS_b mobile terminal 10 notified mobile terminal information 20 wireless zone information 30 communicating mobile terminal information 500 destination wireless zone number 510 Mobile terminal number 520, 710 Required transmission band 530 Notification signal transmission time 540 Communication wireless zone 600 Wireless zone number 610 Free transmission band 700 Terminal number A, D Free transmission band of wireless zone B, C Required transmission band of mobile terminal

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Takehiko Kobayashi 3-4 Hikarinooka, Yokosuka City, Kanagawa Pref. YRP Co., Ltd. Mobile Communication Technology Laboratory (56) References JP-A-6-54366 (JP) (A) JP-A-6-121373 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04B 7/24-7/26 102 H04Q 7/00-7/38

Claims (6)

(57) [Claims] A mobile switching center for controlling the setting of a communication line and a wireless base station for managing a wireless zone , wherein when a mobile terminal moves through the wireless zone during communication, the mobile terminal switches to the communication line of the destination wireless zone. in a mobile communication system configured to continue the communication by performing a handoff to switch, the mobile switching center, means for grasping the transmission band of the idle communication channel of the radio zone managed by the overall region of the wireless base station And when there is a handoff request from the mobile terminal,
It is determined whether or not there is a free communication line in the transmission band required by the mobile terminal in the destination wireless zone. is configured to deliver a notification empty-out without line you notice that there is no vacant communication lines necessary transmission band Te, the mobile terminal, wherein no free line notification from the mobile switching center has arrived and means for notifying the subscriber that, before
After a predetermined time has passed since the notice
The field strength of the currently communicating wireless zone and the nearby wireless zone
And the difference in the electric field strength
When the required level has been reached, the mobile exchange
Means for outputting a handoff request to the station;
Switch to the destination wireless zone after receiving the lineless notification
Hand to notify subscribers when they are replaced
Mobile communication system, comprising a stage. 2. The mobile switching center, for a notified mobile terminal that has already sent the no-line-free notification, sends the notification transmission time, the required transmission band, and the current communication for each destination wireless zone. Hold data for managing information such as the wireless zone number in the, when detecting a change in an idle communication line in the wireless zone of the wireless base station under the control, refer to the data for the corresponding wireless zone, Based on the required transmission band in the data, it is determined whether the notified mobile terminal that can use the transmission band of the free communication line exists, and 2. The mobile communication system according to claim 1, wherein the mobile communication system switches to a destination wireless zone by notifying that a communication line has become free to the wireless zone. Wherein the mobile switching center, if when there is a handoff request from a mobile terminal, there is no free communication lines of the transmission band to the mobile terminal is required for the destination radio zone, the mobile terminal Is searched in the data for managing the notified mobile terminal as to whether or not there is a notified mobile terminal to which the notification of no available line has already been sent to the wireless zone in which communication is currently performed. If there is an already-completed mobile terminal, the transmission band obtained by adding the transmission band of the vacant communication line of the wireless zone in communication with the mobile terminal that has issued the handoff request and the required transmission band of the mobile terminal that has issued the handoff request. Corresponds to the above
To have a Notified viewed mobile terminals necessary transmission bandwidth or more, and the need for notified mobile terminal for transmitting band and the corresponding free communication lines radio zone currently in communication Notified viewed mobile terminals that the corresponding When it is confirmed that the transmission band obtained by adding the transmission band is equal to or more than the required transmission band of the mobile terminal that has issued the handoff request, a communication line is opened in the destination wireless zone for each of the two mobile terminals. Notify that
It switched to the destination radio zone to the case other than the above, and sends the no idle line notification for notifying that there is no vacant communication channel of the transmission bandwidth required for the mobile terminal having issued the handoff request Issues the handoff request to the data for managing the notified mobile terminal.
The mobile communication system according to claim 2 , wherein information about the mobile terminal is registered. Wherein said mobile terminal is currently comparing the field strength of the neighboring radio zone and the field intensity of the radio zone in communication, the level difference of the field strength should the handoff request
Detected that it has fallen below a predetermined level that is greater than
At this time , a handoff notice is sent to the mobile switching center via the radio base station that manages the currently communicating radio zone.
The mobile switching center receives the handoff notice.
At the same time, confirms the transmission band of a vacant communication line of the neighboring wireless zone, and if there is no vacant communication line of the required transmission band requested by the mobile terminal, the mobile terminal transmits to the mobile terminal via the wireless base station. It sends a advance notice for notifying that there is no vacant communication line, wherein the mobile terminal includes a feature that it has a hands-stage you notify the subscriber that the advance notice from the mobile switching center has arrived The mobile communication system according to any one of claims 1 to 3, wherein 5. A communication line for a destination wireless zone, comprising : a mobile switching center for controlling the setting of a communication line; and a wireless base station for managing a wireless zone. A mobile terminal used in a mobile communication system in which communication is continued by performing a handoff to switch to a wireless zone of a movement destination when a handoff request is made.
Free communication lines of the transmission band that requires receives the no idle line notification is notified from the mobile switching center in the absence
Occasionally, a manual stage you notify the subscriber that the, after a predetermined time has elapsed after receiving the notification without the idle line
The field strength of the currently communicating wireless zone and the nearby wireless zone
And the difference in the electric field strength
When the required level has been reached, the mobile exchange
Means for outputting a handoff request to the station, the destination radio zone after receiving a notification without the idle line
To the subscriber when the
A mobile terminal comprising: a notifying unit . 6.further,Electric field of the wireless zone currently communicating
Strength and neighborhoodofWireless zoneCompare with the electric field strength,electric field
The difference in strengthGreater than the handoff required level
IBelow a certain levelDetected thatWhenNow
The transfer is performed via a wireless base station that manages a wireless zone in communication.
Sends a handoff notice to the mobile switching centermeans
And in the nearby wireless zoneI needTransmission bandRegionalFree communication times
Advance notice notified by the mobile switching center when there is no line
ToreceivedSometimes inform the subscriber about it
meansClaims characterized by having:5Transfer of description
Mobile terminal.