JPH11308665A - Group communication method and mobile station - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain smooth and sure transit to a group communication mode among mobile stations at the outside of a base station service zone. SOLUTION: Mobile stations 3e-3g are placed in the service area of a base station 1 and make normal mobile communication. Meanwhile, mobile stations 3a-3d are placed at the outside of the service area of the base station 1, wherein a mobile station 3a acts like a group for instiating mobile station to start a group speech, so that group communication is made among the mobile stations 3a-3d. The mobile station 3a changes its transmission frequency into F1 and its reception frequency into F2, and acts as a caller mobile station and makes a group call to the mobile stations 3b-3d. The mobile stations 3b-3d make communication with the caller mobile station 3a or with other mobile stations via the caller mobile station 3a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system, and more particularly to a system for performing group communication between mobile stations outside the service area of a base station when the mobile station is out of the service area of the base station. .

[0002]

2. Description of the Related Art In a system in which a base station of a mobile communication system performs group communication between mobile stations with a duplex transmission / reception frequency, when the mobile station is out of the service area (out of service area) of the base station, communication becomes impossible. Therefore, in the current system, in order to achieve direct communication between group mobile stations between mobile stations that are out of the service area of the base station and cannot operate the system, the mobile station reception frequency is manually changed to the transmission frequency. And press-talk communication. Further, in the case of the existing duplex system, in order to perform the group communication, in order to prevent radio wave congestion, the transmission / reception frequency is switched to the one-frequency press-talk system, and the communication is performed.

[0003] Japanese Patent Publication No. Hei 4-73646 describes a system which enables group communication between mobile stations outside such a service area.

The system described in the above publication discloses a transmitter for transmitting a radio signal having a predetermined frequency fT, and a transmitter for receiving a radio signal having a predetermined frequency fR (fR ≠ fT). And a receiver for receiving a radio signal of a frequency fR transmitted from a base station, transmitting a radio signal of a frequency fT to the base station, and performing a duplex communication. The radio signal of frequency f
The mobile station is located outside the service area of the base station when the reception level of the radio signal of the frequency fR from the base station falls below a predetermined level. The reception frequency is switched to fT, the radio signal of the frequency fT transmitted from another mobile station in the group is converted to the frequency fR and received, and the reception frequency and the transmission frequency of the mobile station in the group are And performing simplex communication by radio signals of frequency fT to other mobile stations outside the service area of the base station, thereby enabling a simplex communication between the mobile stations outside the service area. I have.

[0005]

However, in the above system, when a mobile station moves out of the base station service area and performs a group call, all the mobile stations in the group need to change the reception frequency. It was impossible to talk with a mobile station whose reception frequency was not changed. In addition, the frequency changing operation is uncertain and reduces the reliability of the system.

An object of the present invention is to eliminate the need for all mobile stations to perform control for changing the reception frequency even outside the base station service area, and to perform group communication using the same transmission / reception frequency as when inside the service area. To provide a highly reliable group communication system capable of shifting to

[0007]

According to the present invention, as a system for realizing group communication outside the service area of a base station, one calling mobile station changes the transmission / reception frequency to the same as that of the system base station, and the mobile station outside the service area receives the call. A call is made to another mobile station. That is, the group mode is set by the group call signal from the mobile station that activates the group call, and the mobile station performs the function as the base station. The group communication is operated with the same system function as in the base station service area without changing to the transmission frequency.

According to the present invention, when group communication is performed when the mobile station is located outside the service area, the mobile stations other than the calling mobile station can change the frequency without changing the frequency. Since a call can be made at the same transmission / reception frequency as in the service area, smooth and reliable group communication can be performed.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A communication area in group communication is basically an area where radio waves of a calling station reach. In the present invention, when a mobile station that has moved out of the service area of the base station in a group performs inter-group communication, the transmission / reception frequency and operation of the mobile station are as follows.

[0010] 1. The mobile station that has moved out of the service area has the same transmission and reception frequency as the base station service area.

2. The mobile station that activates the group communication changes the transmission / reception frequency to the same frequency as the base station frequency (reverse the transmission / reception frequency), and calls out-of-range mobile stations in a group.

3. The called out-of-range mobile station receives the group call signal from the mobile station that has activated the group communication, and performs group communication between the activated mobile station and another out-of-range mobile station by a press talk call.

4. A mobile station that activates group communication has a repeater function in the wireless device, plays the role of an automatic relay function during group communication, and performs reception and return of a received signal.

By the above operation, the group communication area outside the service area can be constructed as an area starting from the calling station.

FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a base station, 2 denotes a service area of the base station 1, 3a to 3g denote mobile stations, and 4 denotes a radio wave arrival area of the mobile station 3a serving as a calling station. In FIG. 1, the mobile stations 3e to 3g are located in the service area of the base station 1, and perform normal mobile radio communication in the service area of the base station 1.

On the other hand, the mobile stations 3a to 3d are located outside the service area of the base station 1, and the mobile station 3a becomes a group-initiated mobile station to start a group call, and
Group communication is performed between 3d.

FIG. 2 is a schematic diagram of means for inverting the transmission / reception frequency of the mobile station according to the present invention. In the mobile station that has activated the group communication, the switches SW1 to SW4 are switched by the mode switching control circuit 17, and the transmitter 1
5 and antenna shared circuit 12 and antenna shared circuit 1
Frequency conversion circuits 13 and 14 are connected between the receiver 2 and the receiver 16, respectively.

The basic unit of the radio equipment of the group-activated mobile station is DUP, RX, TRX C similar to a normal duplex radio.
The REP that is configured by ONT or the like and that wraps the reception into the transmission signal according to the group operation mode is mounted.

Further, the group-activated mobile station operates the relay function of inverting the transmission / reception frequency and diverting the received signal to the transmission side by the group activation. Therefore, by transmitting a signal obtained by combining the communication signal from the own station and the received signal from the transmitter, group communication is enabled.

Next, with reference to FIG. 1, an outline of the operation of group communication outside the base station service area will be described. When the mobile station 3a becomes the calling mobile station and makes a group call to the mobile stations 3b to 3d, the transmission / reception frequency of each mobile station is as follows: mobile station 3a transmission F1 reception F2 mobile station 3b to 3d transmission F2 reception F1 and the calling mobile station 3a press-talks the mobile station 3b.
To 3d at frequency F1.

When the mobile station 3b performs group communication via the mobile station 3a, the mobile station 3b transmits at the frequency F2 allocated during a call. The mobile station 3a receives the signal of the mobile station 3b and converts the received signal to a frequency F
1 and automatically relayed to the mobile stations 3c and 3d. In the mobile stations 3c and 3d, the mobile station 3c
The call b can be monitored.

When the mobile station 3b talks with the mobile station 3c, the mobile station 3b similarly makes a voice call via the calling mobile station 3a and talks with the mobile station 3c.

For the call termination, the mobile station 3a, which is the calling station, has a forced termination or normal termination control function with priority. In addition, it is possible to set to automatically end the call when the no-call state continues for a predetermined time.

[0024]

According to the present invention, when a mobile station moves out of the service area of a base station and performs a group call, only the mobile station that activates the group call changes the transmission / reception frequency, and the other mobile stations change the transmission / reception frequency. Since the group call can be performed without changing the group communication, a smooth and reliable shift to the group communication mode can be performed.

[0025]

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a mobile station according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 base station 2 base station service area 3a to 3g mobile station 4 radio wave arrival area of calling mobile station 3a 11 antenna 12 antenna shared circuit 13, 14 frequency conversion circuit 15 transmitter 16 receiver 17 mode switching control circuit SW1 to SW4 switch

Claims (6)

[Claims] 1. A transmitter for transmitting a radio signal of a predetermined frequency F2, and a transmitter for transmitting a radio signal of a predetermined frequency F2.
A receiver for receiving a radio signal of (F1 ≠ F2), receiving the radio signal of the frequency F1 transmitted from the base station within a service area of the base station, In the mobile radio communication system for performing communication by transmitting the radio signal of the frequency F2, when the plurality of mobile stations are located outside the service area of the base station, one of the plurality of mobile stations One of which activates a group operation mode, inverts a transmission / reception frequency, and functions as a base station, thereby enabling group communication between the plurality of mobile stations outside a service area of the base station. Method 2. The mobile station, which activates the group operation mode, converts a radio signal of the frequency F2 into a radio signal of the frequency F1 and transmits the radio signal of the frequency F1, and converts the radio signal of the frequency F1 into a radio signal of the frequency F2. 2. The group communication method according to claim 1, further comprising means for converting the received signal into a signal, and calling another mobile station outside the service area of the base station using a radio signal of a frequency F1. 3. The mobile station that has activated the group mode has a repeater function in the wireless device of the mobile station, and plays a role of an automatic relay function at the time of group communication to receive and return a received signal. The group communication method according to claim 1, wherein: 4. A mobile station called from a mobile station that has activated the group mode receives a group call signal from the mobile station that has activated the group communication, and has activated the group communication in a press talk call. 2. The group communication method according to claim 1, wherein the group communication is performed between the mobile station and another out-of-service mobile station. 5. A transmitter for transmitting a radio signal of a predetermined frequency F2, and a transmitter for transmitting a radio signal of a predetermined frequency F2.
A receiver for receiving a radio signal of (F1 ≠ F2), receiving the radio signal of the frequency F1 transmitted from the base station, and transmitting the radio signal of the frequency F2 to the base station Then, in a mobile station for mobile radio communication that performs communication within the service area of the base station, the mobile station is output from the transmitter when the group communication mode activation means and the group communication mode are activated. Means for converting a radio signal of a frequency F2 to a radio signal of a frequency F1 and supplying the radio signal of the frequency F1 received by the antenna to a radio signal of a frequency F2 and supplying the radio signal of the frequency F2 to the receiver. A mobile station capable of group communication, comprising: 6. The mobile station according to claim 5, wherein the mobile station that has activated the group communication mode has a repeater function for performing automatic relay during group communication.