JP2000050336A - Hand-over method in mobile radio communication and mobile station system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a efficient hand-over method in mobile communication using pluralities of radio channels. SOLUTION: First a mobile station makes radio communication through a base station 1 through ratio channels 1, 2. Assume that radio channels 1, 3 be channels assigned specifically to respective cells and radio channels 2, 4 be radio channels assigned to pluralities of cells, when the mobile station roams toward a base station 1 and cannot keep a required signal-to-noise power ratio, the mobile station requests hand-over of the radio channel. In the case that the radio channel 2 is used by another mobile station in the base station 2 at a mobile destination, the base station 2 assigns the radio channel 4 used by pluralities of cells to the mobile station. The mobile station hands over the radio communication from the channels 1, 2 into the channels 3, 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to mobile communications. In particular, the present invention relates to handover in mobile communication using a plurality of wireless channels.

[0002]

2. Description of the Related Art Frequency division multiplexing (Frequency Divisi)
In an analog FM system using an on-multiple access (FDMA) system, for example, an analog NTT system, in a switching center or a base station controller monitoring a plurality of base stations, the electric field strength of a mobile station is monitored by peripheral base stations. I have.
When the field strength of the mobile station that is currently talking is reduced, the exchange will hand over the radio channel to the appropriate base station.
This is called a handover initiated by the base station.

[0003] Time Division Multipl
e Access: TDMA) In inter-cell handover of digital mobile communication using the TDMA system, the mobile station measures the electric field strength of a base station during a call and the electric field strength of a base station in a neighboring cell, and transmits to a base station having a strong electric field strength. Handover the radio channel. This will be referred to as a mobile station initiated handover.

[0004] In the technical flow, handover initiated by a base station has been changed to handover initiated by a mobile station.

[0005]

The above-described handovers initiated by the base station and the mobile station are both performed on a single radio channel. In the future, in order to enable large-capacity and highly reliable data transmission in mobile communications, mobile radio systems that use multiple radio channels simultaneously will take into account device compatibility with the current system, deployment to the current frequency band, etc. Promising.

[0006] In a method of allocating a plurality of radio channels, it is considered that a radio channel uniquely allocated to each cell and a radio channel usable in a plurality of cells are used at the same time. According to this method, the number of wireless channels can be switched and used as needed, so that wireless communication can always be performed using the required number of wireless channels.

As a handover method of such a mobile communication system using a plurality of radio channels simultaneously, it can be assumed that a conventional method is applied as it is. However, in the handover method of the mobile radio communication method using a plurality of radio channels as described above, the conventional TD
If the handover method in the communication using one channel of the MA system and the FDMA system is applied as it is, it is not possible to efficiently handover a wireless channel usable in a plurality of cells. This is because the assignment method of the radio channel is different from the assignment method unique to the conventional cell.

It is an object of the present invention to provide an efficient handover method in mobile communication using a plurality of radio channels as described above.

[0009]

In order to solve the above-mentioned problems, the present invention provides a radio channel between a mobile station and a base station, the radio channel being uniquely assigned to each cell and a plurality of cells. In mobile radio communication using a plurality of radio channels with a radio channel that can be used in any cell in the zone to be configured, the mobile station moves to another cell and the current radio base station and the destination In the method of handing over a radio channel with a radio base station of a cell, the handover of a radio channel uniquely assigned to each cell performs a handover to a radio channel uniquely assigned to a destination cell, Handover of a radio channel that can be used in any cell in the zone is performed in any cell in the zone to which the mobile station moves. And performing handover with respect to kill radio channel.

With this configuration, a handover method suitable for each radio channel can be used, and handover can be performed efficiently. The handover of a radio channel that can be used in any cell in the zone is performed by another radio channel that can be used in any cell in a different zone if the radio channel is being used by a target radio base station. Is selected and handover is performed. If the wireless channel is not being used by the destination wireless base station, handover can be performed on the wireless channel. As a result, the use efficiency of the wireless channel can be improved.

In addition, handover can be performed by performing simultaneous multi-station communication using the same radio channel at the same time between the radio base station currently in communication and the radio base station of the destination cell.

According to this handover method, handover can be performed while utilizing the characteristics of diversity reception using a plurality of radio channels.

As processing of the mobile station in such a handover method, the electric field strength of the radio channel with the base station in the serving area that is currently being received and the electric field strength of the control channel reported by the base station in the surrounding area are received. In comparison, a handover request can be made when the compared electric field strength is lower than a preset threshold value.

Further, it is possible to search for both the radio channel uniquely assigned to each cell in the destination base station and the radio channel usable in any cell in the zone.

In the case of simultaneous multi-station communication,
It is also possible to measure the electric field strength of a wireless channel performing multi-station simultaneous communication and stop the communication with the base station whose electric field strength has become equal to or lower than a predetermined value when the electric field intensity has become equal to or lower than a predetermined value.

[0016]

Embodiments of the present invention will be described with reference to the drawings.

FIGS. 1 and 2 show the configuration of a mobile communication system used in the present invention.

FIG. 1 shows an example of a service area of a cell constituted by base stations of a mobile communication network. In FIG.
The cells of base station 1 12 and base station 2 22 constitute service areas 10 and 20, respectively. The mobile station 30 is currently in the service area 10 and the base station 1
12 and a plurality of radio channels assigned to each cell and a plurality of radio channels assigned to a zone constituted by a plurality of cells. The mobile station 30 is moving in the direction of the service area 20 provided by the base station 222. The base station controller 50 manages wireless channels set by the base stations 1 and 2 and the like.

FIG. 2 shows an example of the configuration of the mobile communication network shown in FIG. FIG. 2 shows a connection relationship between the base station 1 12, the base station 2 22, the exchange 40, and the base station control device 50 via a control line and a communication line. The base station control device 50 connects the wired channel of the exchange 40 with the base stations 1 and 2.
Manages wireless channels. According to an instruction from the base station control device 50, a communication line to the mobile station 30 is set.

The present invention relates to a handover in a mobile station 30 that is communicating using a radio channel assigned to each cell and a radio channel assigned to a plurality of cells forming a zone. . Hereinafter, the handover will be described in detail.

(Embodiment 1) In Embodiment 1, with respect to handover of a radio channel uniquely assigned to each cell, handover is performed to a radio channel uniquely assigned to a destination cell. Regarding handover of radio channels that can be used in multiple cells,
If the wireless channel is being used by the destination wireless base station, handover is performed to another wireless channel that can be used by a plurality of wireless channels.

[0022] Of the plurality of radio channels, a radio channel assigned to a unique cell is, for example, a conventional TDMA.
It is possible to perform handover by a handover method similar to the FDMA method and the FDMA method.

When a radio channel usable in a plurality of cells currently in use at the destination base station is being used, a handover is performed on a radio channel usable in a plurality of cells at the destination base station. Going over. By performing the handover in this way, it is possible to increase the subscriber capacity by a wireless channel that can be used in a plurality of cells.

The first embodiment will be briefly described with reference to FIG. In FIG. 3, the same configuration as in FIG. 1 and FIG.
The same reference numerals are used.

In FIG. 3, first, the mobile station 30 performs radio communication with the base station 112 via the radio channels 1 and 2. Among these radio channels, radio channel 1 is a radio channel assigned to each cell, and radio channel 2 is a radio channel assigned to a plurality of cells. Therefore, the wireless channel 2 is the base station 2
22 can also be used.

As the mobile station 30 moves toward the base station 222, the radio wave of the base station 112 becomes weaker. When the required signal-to-noise power ratio cannot be maintained, the mobile station 30 requests the base station 222 to perform a handover of the radio channel of the base station 1. At this time, the destination base station 22
When the wireless channel 2 is used by another mobile station in 2, the base station 222 allocates the wireless channel 4 that can be used in a plurality of cells to the mobile station in the same manner as the wireless channel 2. The mobile station 30 performs handover from the wireless channels 1 and 2 to the wireless channels 3 and 4.

This handover control will be described in detail with reference to a sequence diagram shown in FIG.

In FIG. 4, first, the mobile station is the base station 1.
And a call using the carrier waves 1 and 2 (S102).
When the radio wave of the base station 1 is weakened by the movement of the mobile station, a weak electric field report is made to the base station controller (S104). The base station control device that has received the report instructs the exchange to switch the wired channel (S106). Similarly, the mobile station is instructed to switch from the carrier 1 assigned to each cell to the carrier 3 by the base station 2 (S10).
7). Thereafter, the communication is continued using the carrier 3 from the base station 2 and the carrier 2 from the base station 1 (S10).
8).

The mobile station searches for a radio channel usable in a plurality of cells, in this case, a carrier (S110), and requests the base station controller to switch from carrier 2 to carrier 4 usable in a plurality of cells (S110). S112). The base station controller instructs the exchange to switch the wired channel according to the request of the mobile station (S114). Also, the mobile station is permitted to switch from the carrier 2 of the base station 1 to the carrier 4 of the base station 2 (S115). Thus, the mobile station can continue the call using the carrier 3 and the carrier 4 from the base station 2 (S116).

By using the above-described sequence, it is possible to control handover of a plurality of radio channels having different management modes from the base station 1 to the base station 2.

(Embodiment 2) In Embodiment 2, with regard to handover of a radio channel uniquely assigned to each cell, handover is performed to a radio channel uniquely assigned to a destination cell. Regarding handover of radio channels that can be used in multiple cells,
If the same wireless channel is not in use at the destination wireless base station, handover to the same wireless channel is performed.

In the second embodiment, with respect to handover of a radio channel that can be used in a plurality of cells, if the radio channel currently in use at the destination base station is free, the radio channel is used as it is, Handover of base station. At this time, the wireless channel is handed over without performing the multi-station simultaneous communication described later. Thereby, the use efficiency of the wireless channel can be improved.

FIG. 5 shows a handover according to the second embodiment. 5, the same components as those in FIGS. 1 to 3 are denoted by the same reference numerals.

In FIG. 5, first, the mobile station 30 performs radio communication with the base station 112 via the radio channels 1 and 2. Among these radio channels, radio channel 1 is a radio channel assigned to each cell, and radio channel 2 is a radio channel assigned to a plurality of cells.

Therefore, the radio channel 2 is connected to the base station 222.
Can also be used.

As the mobile station moves toward base station 222, the radio wave of base station 1 becomes weaker. When the required signal-to-noise power ratio cannot be maintained, the mobile station 30
22 requests handover of the radio channel of the base station 112. At this time, if the wireless channel 2 is a free wireless channel in the destination base station 2, the base station 2
Allocates radio channel 2 to the mobile station. The mobile station hands over from radio channels 1 and 2 to radio channels 3 and 2.

The control of the handover according to the second embodiment will be described in detail with reference to the sequence diagram of FIG. FIG.
In the sequence diagram of FIG. 5, the same reference numerals are given to the same sequence as the sequence diagram of FIG.

In FIG. 6, first, the mobile station talks with base station 1 using carrier waves 1 and 2 (S10).
2). When the radio wave of the base station 1 is weakened by the movement of the mobile station, a weak electric field is reported to the base station controller (S10).
4). The base station control device that has received the report instructs the exchange to switch the wired channel (S106). Similarly, the mobile station is instructed to switch from the carrier 1 assigned to each cell to the carrier 3 by the base station 2 (S107). Thereafter, the mobile station continues the call using the carrier 3 from the base station 2 and the carrier 2 from the base station 1 (S108).

The mobile station searches for a carrier that can be used in a plurality of cells (S110). If the carrier 2 is not used in the destination cell, the carrier 2 is transmitted from the base station 1 to 2 to the base station controller. Is requested (S112). The base station controller instructs the exchange to switch the wired channel according to the request of the mobile station (S114). In addition, the mobile station is permitted to switch from carrier 2 of base station 1 to carrier 2 of base station 2 (S115). Thus, the mobile station can continue the call using the carrier 3 and the carrier 2 from the base station 2 (S116 ').

In this way, it is possible to control the handover of a plurality of radio channels having different management modes from the base station 1 to the base station 2.

(Embodiment 3) In Embodiment 3, with respect to a radio channel uniquely assigned to each cell, handover is performed to a radio channel uniquely assigned to a destination cell. Regarding handover of a radio channel that can be used in a plurality of cells, the same radio channel is used in a destination cell, and a mobile station performs a plurality of base station simultaneous communication (multi-station simultaneous communication) using this radio channel. , A wireless channel handover is being performed.

In the third embodiment, as a handover of a radio channel that can be used in a plurality of cells, the same radio channel is transmitted by a destination base station so that the mobile station performs the handover by multi-station simultaneous communication. Is going. This is called Code Division Multipl
e Access (CDMA) has the same effect as the so-called diversity handover. in this way,
By performing the handover, the handover can be performed while utilizing the characteristics of the diversity reception by using a plurality of radio channels.

FIG. 7 shows a third embodiment. In FIG.
The same components as those in FIGS. 1 to 3 and 5 are denoted by the same reference numerals.

Now, referring to FIG.
Is in the service area 10 of the cell of the base station 112 and is communicating with the base station 112 using a plurality of radio channels, as described with reference to FIG. Mobile station 30
Moves in the direction of the arrow, and enters an area where the service areas of the base station 112 and the base station 222 overlap. Then, the radio wave from the base station 112 becomes weak. Therefore, among the plurality of radio channels used by the mobile station 30, the radio channels uniquely assigned to each cell are from the base station 112 to the base station 222.
Perform a handover to

In the case of a radio channel allocated to a plurality of cells, the mobile station 30 desires the base station 222 to allocate the same radio channel as the base station 112. Upon accepting the request from the mobile station 30, the base station 222 sets up a line to the mobile station 30 using the same wireless channel as that used by the base station 112. When a series of line settings are completed, it becomes possible for the mobile station 30 to perform simultaneous multiple base station communication between the base station 112 and the base station 222. After communicating with a plurality of base stations at the same time, the wireless channel of the base station with the weaker electric field is disconnected.
As a result, the handover of the radio channel allocated to a plurality of cells is performed.

FIG. 8 shows an example of handover control according to the third embodiment. FIG. 8 is a sequence diagram, and FIG.
The same reference numerals are given to the same sequence as in FIG. 6 and FIG. In FIG. 8, first, the mobile station is communicating with base station 1 using carrier waves 1 and 2 (S102). When the radio wave of the base station 1 is weakened by the movement of the mobile station, a weak electric field report is made to the base station controller (S104). The base station control device that has received the report instructs the exchange to switch the wired channel (S106). The base station controller also
The mobile station is also instructed to switch from the carrier 1 assigned to each cell to the carrier 3 by the base station 2 (S107).

The mobile station searches for a carrier that can be used in a plurality of cells (S110). If carrier 2 is not used in the destination cell, the carrier 2 is transmitted to the base station controller by the base station 1 and the base station. (S12).
1). The base station control device instructs the exchange to switch the wired channel according to the request of the mobile station (S122).
In addition, the base station 2 is transmitted from the carrier 2 of the base station 1 to the mobile station.
Of the multi-station simultaneous communication to the carrier 2 of the communication (S12)
3). Further, when the mobile station moves and the electric field strength of the carrier 2 from the base station 1 decreases, the mobile station reports this (S125). The base station control device determines the carrier 2 of the base station 1.
Is requested to the mobile station to release (S126), and a switching instruction is issued to the exchange (S127). Thus, the mobile station talks with the base station 2 using the carrier 2 and the carrier 3 (S128).

Thus, it is possible to perform handover control from the base station 1 to the base station 2 while simultaneously performing multi-station simultaneous transmission on a plurality of wireless channels having different management modes.

Note that the wireless channel in the description of each of the above embodiments means a wireless channel distinguished by frequency, time, spreading code, and the like.

(Control in Mobile Station) FIG. 9 is a flowchart showing in detail the processing in the mobile station when all of the first to third embodiments are implemented.

In FIG. 9, the mobile station always detects the electric field strength of the radio channel with the base station in the service area (S202), and the area around the area where the mobile station is present. (S204). The detected field strength of the service area,
The electric field strength in the surrounding area is compared (S206), and if the difference is equal to or larger than the threshold value, there is no need to perform handover, and communication with the base station in the current service area is performed as it is ( S210). If the difference is equal to or larger than the threshold, first, handover is performed on a radio channel uniquely assigned to the cell among a plurality of channels used for communication between the mobile station and the base station (S212). .

Next, a handover process is performed on the radio channels allocated to a plurality of cells.

The mobile station searches for a wireless channel in the destination base station. First, the wireless channel allocated to a plurality of cells currently used for communication with the base station is determined by the destination base station. In step S214, it is detected whether the device is in use.

If it is in use, a vacant radio channel is checked from among the radio channels allocated to the other cells (S216), and handover is performed for it (S218). If it is not in use, it detects whether or not simultaneous multi-station communication with the destination base station is possible using radio channels assigned to a plurality of cells currently used for communication with the base station. (S220).

If simultaneous multi-station communication is not possible, the base station connected to the same radio channel is changed (S222). Thereby, the handover process of the radio channel allocated to the plurality of cells is performed (S224).

If simultaneous multi-station communication is possible, multi-station simultaneous communication is performed with the base station currently communicating and the destination base station on the same wireless channel (S226). The mobile station measures the electric field strength of a plurality of communicating base stations during simultaneous multi-station communication (S228). When the electric field strength becomes equal to or less than the predetermined threshold value, the base station releases the radio channel of the base station whose value is equal to or less than the threshold value (S232). Thereby, the handover process of the radio channel allocated to the plurality of cells is performed (S234).

As described above, each embodiment follows the same process up to the presence or absence of the use of the radio channel allocated to a plurality of cells. If the radio channel is in use, a free radio channel is searched from radio channels allocated to a plurality of cells, and if the radio channel is not used, the same radio channel is set as the destination base station. . At this time, the handover process differs depending on the presence / absence of multi-station simultaneous transmission. In the present invention, in mobile communication using wireless channels of different management modes at the same time, a handover control method for a wireless channel suitable for each is applied. This enables more efficient handover control as compared with the conventional TDMA and FDMA handover control methods.

FIG. 1 shows a configuration example of a mobile station in which this control is performed.
0 is shown. The details of the configuration of the mobile station vary depending on the type of radio channel used (which is distinguished by frequency, time, spreading code, etc.). In FIG. 10, mobile device 100
Are a plurality of transmitters 122, 124 and receivers 132,
134, baseband processing unit 110, microphone 102 and speaker 104, control unit 140, memory 142, multiple antenna duplexers 152, 154, antenna 15
6,158, etc.

FIG. 10 shows an example in which two transmitters and receivers are used as a plurality of transmitters and receivers. However, the number is not limited to this, and may be any number. . FIG. 10 shows an example of voice input,
When transmitting and receiving data, an input / output terminal from a computer may be provided. The above-described handover control of the present invention is performed by using the control unit 140 and the memory 142 which are configured by a CPU or the like.

The voice from the user is transmitted to the microphone 102
, Processing such as voice encoding is performed by the baseband processing unit 110. The processed signal is transmitted to the transmitter 1
12, 124, and are modulated into a radio signal.
Radio waves are radiated from different antennas 156 and 158 from the transmission / reception duplexers 152 and 154, respectively. At this time, the plurality of transmitters 1 are stored in the control unit 140 and the memory 142.
22 and 124 are controlled.

In reception, a plurality of antennas 156,
158, and receives 2 via the duplexer 152, 154.
Wireless signals are input to the two receivers 132 and 134. The receivers 132 and 134 are controlled by the control unit 140 and the memory 142 to measure the electric field strength and determine the level. Thus, the above-described overhand control can be performed.

Now, the signals demodulated in the receivers 132 and 134 are subjected to processing such as decoding in the baseband processing section 110, and sound can be reproduced from the speaker 104.

At this time, even when the mobile station is at the cell edge, by performing the above-described handover control, stable voice communication can be performed, and highly reliable wireless communication can be performed. it can.

[0064]

The effects of the present invention are as follows.

(1) In a mobile communication method using a plurality of radio channels, an efficient radio channel handover method can be provided.

(2) Handover by simultaneous multi-station communication becomes possible.

(3) It is possible to flexibly hand over wireless channels having different management modes.

(4) There is compatibility with the handover method in the existing mobile communication system.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a service area of a cell constituted by base stations of a mobile communication network.

FIG. 2 is a block diagram showing an example of the configuration of the mobile communication network shown in FIG.

FIG. 3 is a diagram illustrating a handover according to the first embodiment;

FIG. 4 is a sequence diagram illustrating handover according to the first embodiment in detail.

FIG. 5 is a diagram illustrating a handover according to a second embodiment.

FIG. 6 is a sequence diagram illustrating handover according to the second embodiment in detail.

FIG. 7 is a diagram illustrating a handover according to a third embodiment.

FIG. 8 is a sequence diagram showing a handover in a third embodiment in detail.

FIG. 9 is a diagram illustrating a control flow according to the first to third embodiments.

FIG. 10 is a block diagram illustrating a configuration example of a mobile station used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Service area 20 Service area 30 Mobile device 30 Mobile station 40 Switch 50 Base station controller 100 Mobile device 102 Microphone 104 Speaker 110 Baseband processing unit 122, 124 Transmitter 132, 134 Receiver 140 Control unit 142 Memory 152, 154 Antenna Duplexer 156,158 antenna

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5K067 AA21 AA33 BB02 CC02 CC04 DD43 DD44 DD57 EE02 EE24 HH01 HH21 HH22 JJ11 JJ17 JJ35 JJ39

Claims (10)

[Claims] 1. A radio channel between a mobile station and a base station, wherein a plurality of radio channels uniquely assigned to each cell and a plurality of radio channels usable in any cell in a zone composed of a plurality of cells are provided. In the mobile radio communication using the radio channel, in the handover method of the radio channel between the radio base station of the current call and the radio base station of the destination cell by moving the mobile station to another cell, The handover of the radio channel uniquely assigned to the cell performs the handover to the radio channel uniquely assigned to the destination cell, and the handover of the radio channel that can be used in any cell in the zone is Performing a handover on a radio channel that can be used in any cell in the destination zone; Handover method for the butterflies. 2. The handover method according to claim 1, wherein the handover of a radio channel usable in any cell in the zone is performed when the radio base station of the movement destination is using the radio channel. A handover method, wherein a handover is performed by selecting another radio channel that can be used in any cell in the different zone. 3. The handover method according to claim 1, wherein the handover of a radio channel that can be used in any cell in the zone is performed when the radio channel is not used by a destination radio base station. A handover method, wherein a handover is performed for the wireless channel. 4. The handover method according to claim 3, wherein the handover of a radio channel usable in any cell in the zone further includes a radio base station currently in communication and a radio base station of a destination cell. A handover method comprising: performing a multi-station simultaneous communication by simultaneously using the same wireless channel for a handover. 5. The handover method according to claim 1, wherein the mobile station reports the electric field strength of a radio channel with a base station in a serving area which is currently being received and a base station in a surrounding area. A handover method comprising: comparing the electric field strengths of the control channels to be performed; and making a handover request when the compared electric field strengths are lower than a preset threshold value. 6. The handover method according to claim 5, wherein the mobile station can further use any cell in the zone and the radio channel uniquely assigned to each cell in the destination base station. A handover method comprising performing a search for both wireless channels. 7. The handover method according to claim 6, wherein the mobile station further measures an electric field strength of a radio channel performing the multi-station simultaneous communication when the multi-station simultaneous communication is being performed. A handover method comprising: stopping a call with a base station having a strength equal to or less than a predetermined value when the strength is equal to or less than a predetermined value. 8. A radio channel between a mobile station and a base station, a plurality of radio channels uniquely assigned to each cell and a plurality of radio channels usable in any cell within a zone composed of a plurality of cells. In a mobile station device performing mobile radio communication using the wireless channel of the present invention, the electric field strength of the radio channel with the base station in the serving area currently being received and the electric field of the control channel reported by the base station in the surrounding area are received. Comparing the strength, making a handover request when the compared electric field strength is lower than a preset threshold value, the radio channel and zone uniquely assigned to each cell in the destination base station Search for both of the wireless channels that can be used in any of the cells, and assign a unique address to each of the cells. The handover of the assigned radio channel performs a handover to the radio channel uniquely assigned to the destination cell, and the handover of a radio channel that can be used in any cell in the zone is performed in the zone of the destination. A mobile station apparatus for performing handover on a radio channel usable in any of the cells. 9. The mobile station apparatus according to claim 8, wherein a handover of a radio channel usable in any cell in the zone further includes a radio base station currently in communication and a radio base station in a destination cell. A mobile station apparatus characterized in that a handover is performed by performing simultaneous multi-station communication using the same wireless channel at the same time. 10. The mobile station device according to claim 9,
Furthermore, the electric field strength of a wireless channel performing simultaneous multi-station communication is measured, and when the electric field strength falls below a predetermined value,
A mobile station apparatus for stopping a call with a base station having a predetermined value or less.