JPH07111475A - Group communication system for mobile radio equipment - Google Patents

Abstract

PURPOSE:To receive a group call signal even on the way of group communication by providing a redial control means in a caller station side and sending the group call signal even during group communication. CONSTITUTION:When a control section 4 makes group dialing, a receiver 2 makes carrier sense by the carrier sense control from the control section 4 to search a dead channel. Then a group call signal including information of a call group and dead channel information 7 is generated by the control section 4 and a transmitter 3 sends the signal from an antenna 1. When there is a station of a registered group among stations receiving the transmission information, the station transits to a communication state in the standby operation state and the communication is made available. A group call station gives a command of sending a group call signal from a redial control section 5 to the control section 4 after the lapse of a predetermined time from the dialing and the transmitter 3 sends the group call signal again from the antenna 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice group communication system for mobile radios in an MCA system.

[0002]

2. Description of the Related Art In a conventional MCA system having a control-dedicated channel, a group-selecting call signal originated by a calling station is transmitted to a wireless station which is in the same group as the calling station, such as delay in power-on. If the wireless station could not be received for some reason, the wireless station could not perform group communication and was left behind from the group.

FIG. 4 shows a timing chart of a conventional calling system. The channels are composed of a control dedicated channel 9 and a communication channel (n channel) 14. When the station A makes the call operation 10, the station A wireless device receives the carrier sense 1
Start 1 and check whether there is a carrier in each channel, and search for a channel with no carrier. In FIG. 4, assuming that the n channel is a channel in which no carrier is detected, station A sends a group call signal 12 including call group number information and empty channel information n on the control dedicated channel.

If the station B is in the standby operation before the call from the station A, the connection is established, the channel is shifted to the call channel, and the call is started. However, when the station B turns on the power of the wireless device 15 after calling the station A, the group call signal 12 of the station A cannot be received, and the communication is not established, and the call cannot be performed.

[0005]

As described above, according to the conventional technique, even a station that joins a group during group communication is not turned on by the power being turned on before the group communication. And, there is a drawback that the communication is not called.
An object of the present invention is to eliminate this drawback and to provide a group communication system capable of receiving a group call signal even in the middle of group communication.

[0006]

According to the present invention, in order to solve the above-mentioned problems, recalling control is provided on the group calling station side, and after Ci monitoring operation, the group calling signal is reissued on the control dedicated channel. It was something that was called.

[0007]

[Operation] By providing the recall control means in this way,
Since the group call signal is transmitted even during group communication,
A wireless device that is a member of a group can receive a group call signal even during communication.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of a radio device according to an embodiment of the present invention. In the figure, 1 is an antenna, 2 is a receiver, and 3
Is a transmitter, 4 is a control unit composed of a microcomputer and a modem, and 5 is re-call control for sending a group call signal. When the control unit 4 performs a group call operation, the receiver 2 performs carrier sense to search for an empty channel by the carrier sense control from the control unit 4, and makes a group call including the call group information and the empty channel information. A call signal is generated by the control unit 4 and transmitted from the transmitter 3 through the antenna 1.

Among the stations that have received the transmission information, if it is a station of a registered group, it shifts to the communication state in the standby operation state and communication is possible. After a certain period of time has passed after the call was issued by the group calling station, the re-call control 5 instructs the control unit 4 to send the group call signal, and the transmitter 3 retransmits the group call signal from the antenna 1.

FIG. 2 is a flow chart showing the group call operation of the wireless device in this embodiment. In FIG. 2, the feature of the present invention lies in the step of calling the group selective calling signal 6 for re-calling at regular time intervals, in contrast to the operation of the conventional wireless device.

FIG. 3 is a timing chart showing a group calling method according to the present invention. As shown in the figure, since the group A call signal 7 is periodically transmitted from the station A even after the Ci monitoring, even if the station B is turned on 15 during the group communication, the group call signal 7 is transmitted. Is received reliably,
The called operation 8 can be performed.

[0012]

As described above, according to the present invention, it is possible to realize a communication system capable of surely receiving a group call signal and communicating even if the station is powered on during the group communication. it can.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a wireless device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the wireless device according to the embodiment of the present invention.

FIG. 3 is a timing chart showing a group calling method according to the present invention.

FIG. 4 is a timing chart showing a conventional group calling method.

[Explanation of symbols]

 1 Antenna 2 Receiver 3 Transmitter 4 Control Unit by Modem and Microcomputer 5 Recall Control Unit 6 Group Selective Call Call 7 Group (Selective Call) Call Signal 8 Station B Called Operation 9 Control Dedicated Channel 10 Station A Call operation 11 Station A carrier sense 12 Group (selective call) call signal 13 Ci monitor 14 Call channel 15 Power on

Claims (1)

[Claims] 1. A group communication system for mobile radios in a MCA system having a dedicated control channel, characterized in that a calling station periodically transmits a call signal by group communication. method.