JP3226751B2 - Mobile communication system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital cordless telephone system which uses a TDM between a master station and each slave station.
The present invention relates to a mobile communication system connected using the A-TDD scheme.

[0002]

2. Description of the Related Art In recent years, various mobile communication systems have been developed with the development of communication technology and the expansion of communication needs.
One of them is PHS (Personal Handy Phone System)
) Is a digital cordless telephone device.

[0003] This type of device comprises, for example, a base unit connected to a public telephone network via a subscriber line, and a plurality of slave units connected to the base unit via a radio channel.
The radio access system between the master unit and each slave unit includes a four-channel multiplex multi-carrier TDMA (Time Division Multiplex).
Access)-The TDD (Time Division Duplex) method is adopted. This type of access method is, for example, as shown in FIG. 9, a transmission signal frame transmitted by each of a plurality of radio frequencies f1 to fn is converted into four times for a forward link used for communication from each slave unit to a master unit. Slots FL1 to FL4, and four time slots RL1 to RL4 for the reverse link from the master unit to the respective slave units. Each of these time slots FL1 to FL4 for the forward link and each time slot for the reverse link. Wireless communication is performed by using pairs of RL1 to RL4 as channels. That is,
Four channels are provided by one radio frequency.

Incidentally, the PHS has 37 radio frequencies (f1 to f37), of which f12 and f18 are used for control.
Others are used for calls. Of the radio frequencies for the call, f1 to f10 are used for a direct call between slave units described later, and the rest are used for an outside line call and a relay call between the slave units.

In general, a digital cordless telephone apparatus has two communication modes: an external call mode in which a slave unit communicates with the public telephone network via a master unit via an external line, and an extension line mode in which a master unit is relayed between slave units. And a relay communication mode between child devices. The communication in the relay communication mode between the slaves is performed as follows. FIG. 7 shows an example of the sequence.

That is, when a calling operation is performed in the slave unit PS1, first, a "link channel establishment request" signal is transmitted from the slave unit PS1 to the master unit BS. Receiving this signal, base station BS returns a "link channel assignment" signal to source handset PS1 to designate a communication channel. For this reason, the above-mentioned wireless communication channel is set between the originating slave unit PS1 and the master unit. At the same time, master unit BS sends an incoming call notification signal to slave unit PS2 of the called party. Upon receiving the incoming call notification signal, the slave unit PS2
A "link channel establishment request" signal is transmitted to the master unit BS. On the other hand, the base station BS sets “link channel assignment”.
Send back signal to specify another wireless channel. Therefore, another wireless communication channel is set between the slave unit PS2 and the master unit BS. In this way, a wireless communication link by each of the above-mentioned wireless communication channels is formed between the mobile station PS1 of the transmission source and the mobile station PS2 of the destination via the base station BS. A call can be made via.

However, since one transmission frame is composed of four channels as described above, the number of channels that can be simultaneously used by the base station BS is limited to four channels.
Moreover, one of these channels is used as a control channel, so that the number of channels that can be substantially used as a communication channel is three. For this reason, when an extension call between the slave units relaying the master unit BS as described above is performed, the master unit BS spends two channels on the extension call between the slave units, and the remaining communication channels are There is only one channel. Therefore, in this state, the master unit BS can only relay outside line calls by one slave unit,
For example, as shown in FIG. 10, even when a link channel establishment request for an extension call comes from another slave unit PS3, it cannot be accepted. That is, only one set of extension telephone calls can be made at the same time.

Therefore, recently, in addition to the external line communication mode and the above-mentioned relay communication mode between the child devices relaying the parent device, a child device which directly makes an extension call without relaying the parent device between the child devices is provided. It is being considered to provide a direct call mode during the call.
FIG. 8 is a diagram showing a call operation sequence in the direct call mode between child devices.

That is, when an extension call is made in the direct call mode between the slave units, for example, the user tries to make a call.
In each of the slave units, the speaker operates the mode changeover switch to set the talk mode to the direct talk mode between the slave units. Then, when the speaker performs a calling operation in one of the slave units, a calling signal is transmitted from the calling slave unit PS1 to the called slave unit PS2. On the other hand, the called slave unit PS2
In this state, when a call signal addressed to the terminal itself is received in this state, the slave unit PS2 of this destination is thereafter received.
The transmission and reception of a synchronization signal is performed between and the slave unit PS1 of the transmission source. The transmission and reception of this synchronization signal causes the
When the synchronization between PS1 and PS2 is established,
A wireless communication link that does not relay the base station BS is formed between 1 and PS2, and thereafter, communication becomes possible.

However, in a conventional apparatus having such a direct communication mode between slave units, when a direct call is performed between the slave units, as described above, both the calling side and the called side have the slave side. The call mode must be set in advance to the direct call mode between handset units by manual operation. For this reason, it is not possible to make a direct call between the child devices with the child device which is not set to the direct telephone mode between the child devices, and in this case, it is necessary to rely on an extension call relaying the parent device. That is, the utilization rate of the direct call mode between the slave units cannot be increased. If the user forgets to return the call mode from the direct call mode between handset units to the relay call mode between handset units, the radio channel for standby differs between the direct call mode between handset units and the relay call mode between handset units. Even if it occurs, there is a problem that it becomes impossible to respond to this.

[0011]

As described above, in the conventional apparatus, the setting and canceling of the direct talk mode between the slave units must all be performed manually by the speaker. For this reason, it is not possible to make a direct telephone call between the child devices with a child device whose telephone call mode is not set to the direct telephone call mode between the child devices, and it is impossible to increase the utilization rate of the direct telephone call mode between the child devices. In addition, if the call mode is set to the direct call mode between slave units in order to increase the usage rate of the direct call mode between handset units, it will not be possible to respond to an incoming external line during this time. Occurs.

The present invention has been made in view of the above circumstances. It is an object of the present invention to enable automatic setting and release of a direct communication mode between slave stations without relying on manual operation. Accordingly, it is an object of the present invention to provide a mobile communication system capable of increasing the utilization rate of the direct communication mode between slave stations and ensuring that the slave station can receive an incoming external call.

[0013]

To achieve the above object, the present invention provides a master station connected to a wired communication line and a plurality of slave stations connected to the master station via a radio channel. A slave station relay communication for connecting the master station and each slave station using a TDMA-TDD system and connecting the slave stations via the master station as a communication mode to enable communication; Mode, and a mobile communication system including a direct communication mode between slave stations that enables communication by directly connecting slave stations, wherein the master station issues a request for switching from the slave station to the direct communication mode between slave stations to the master station. When a call control signal including the communication signal arrives, a response signal including an instruction to switch to the direct communication mode between slave stations is sent to the slave station, and the destination station is switched to the direct communication mode between slave stations. Means for transmitting an incoming call control signal including an instruction, and Each of the slave stations has mode designation means for designating and inputting a direct communication mode between slave stations, and when the direct communication mode between slave stations is designated by the mode designation means upon calling, Means for transmitting a transmission control signal including a request for switching to the direct communication mode between slave stations, and a response signal including an instruction for switching to the direct communication mode between slave stations, when the master station returns the response signal. Means for switching the communication mode of the slave station from the relay communication mode between the slave stations to the direct communication mode between the slave stations, and an incoming call control signal including an instruction for switching from the master station to the slave station direct communication mode in the standby state. Means for switching the mode of the own station from the inter-slave relay communication mode to the inter-slave direct communication mode, and a slave station of a communication partner with the inter-slave direct communication mode set. Follow the prescribed procedure between Direct connection control means for connecting via a wireless channel for direct communication between slave stations, and a predetermined time from when a signal including a switching instruction to the direct communication mode between slave stations arrives from the master station. If not shifted to direct communication between slave stations within, and when the direct communication between slave stations is terminated, respectively restore the mode of the own station from the direct communication mode between slave stations to the relay communication mode between slave stations, Thus, a mode restoration control means for setting a state capable of responding to an incoming call from the master station is provided.

[0014]

[0015]

As a result, according to the present invention, when a call is made in a state in which the direct communication mode between slave stations is set in the source slave station, the mode is switched from the master station to the destination slave station together with the call notification. The instruction is notified, and the destination slave station is automatically set to the direct communication mode between slave stations. Therefore, thereafter, connection control for direct communication between the slave stations is performed between the two slave stations, whereby the two slave stations are directly connected via a wireless channel to enable wireless communication. Also with it
When the communication in the direct communication mode between the slave stations ends abnormally or when the communication ends, the communication mode of each slave station is automatically changed from the direct communication mode between the slave stations to the relay communication mode between the slave stations for relaying the master station. Return.

Therefore, the setting operation and the returning operation of the direct communication mode between the slave stations by the speaker become unnecessary, and thereby the utilization rate of the direct communication between the slave stations is increased. Also, since it will not be left in the direct communication mode between slave stations,
When an outside line arrives, it can be reliably received.

[0017]

1 and 2 are circuit block diagrams showing the configurations of a master unit BS and a slave unit PS of a digital cordless telephone apparatus according to an embodiment of the present invention, respectively. FIG.
First, the base station BS includes a radio unit 1 having an antenna 11, a modem unit 2, a TDMA unit 3, a communication unit 4,
And a control unit 5. That is, the radio frequency signal arriving from the slave unit PS is received by the antenna 11 and then input to the receiving unit 13 via the high frequency switch 12 of the radio unit 1. In the receiving unit 13, the received radio frequency signal is mixed with a receiving local oscillation signal generated from the frequency synthesizer 14 and frequency-converted into a receiving intermediate frequency signal. The local oscillation frequency generated by the frequency synthesizer 14 is instructed by the control unit 5 according to the radio channel frequency. Further, the radio unit 1 is provided with a reception field strength detection unit (RSSI) 16. The reception electric field strength detection section 16 detects the reception electric field strength of the radio frequency signal arriving from the slave unit, and the detected value is applied to the control section 5.
Will be notified.

The received intermediate frequency signal output from the receiving unit 13 is input to the demodulation unit 21 of the modem unit 2. The demodulation section 21 performs digital demodulation of the received intermediate frequency signal, thereby reproducing a digital communication signal.
In the TDMA decoding unit 31 of the TDMA unit 3, the control unit 5
The digital communication signal is decomposed for each time slot in accordance with the instruction, and the decomposed digital communication signal is input to the communication unit 4. The communication unit 4 includes an adaptive difference PCM transcoder (ADPCM-TRANSCODER) 41
And a PCM codec (PCM-CODEC) 42, and the digital speech signal is generated by the adaptive difference PCM.
The signal is sequentially decoded by the transcoder 41 and the PCM codec 42 and reproduced as an analog call signal. This analog call signal is transmitted to the subscriber line SL of the public telephone network (not shown) via the hybrid circuit 43 in the case of an external call, whereas the PCM is used in the case of an internal call.
The signal is fed back to the codec 42.

On the other hand, analog speech signals arriving from the public telephone network via the subscriber line SL or speech signals returned from the PCM codec 42 are sequentially encoded by the PCM codec 42 and the adaptive difference PCM transcoder 41. The signal is converted into a digital communication signal. In the TDMA encoder 32, the adaptive difference transcoder 41
Is multiplexed by inserting it into a desired time slot, and the multiplexed digital call signal is input to the modulator 22. In the modulation section 22, the carrier signal is digitally modulated by the digital communication signal, and this modulated carrier signal is
Is input to In the transmitting unit 15, the modulated carrier signal is mixed with a transmitting local oscillation signal generated from the frequency synthesizer 14 to be frequency-converted to a radio channel frequency instructed by the control unit 5, and further to a predetermined transmission power. Amplified to the level. Then, the radio frequency signal output from the transmitting unit 15 is transmitted from the antenna 11 to the slave unit PS via the high frequency switch 12.

The control unit 5 includes, for example, a microcomputer as a main control unit.
External line connection control means 51 and relay connection control means 52 between slave units
And direct connection control means 53 between child devices.

The external line connection control means 51 connects between the slave unit PS and the public telephone network to enable external line communication of the slave unit PS, and sets an empty communication channel with the slave unit PS. And processing for making and receiving calls to and from a public telephone network.

The inter-slave unit relay connection control means 52
, A call signal in the relay call mode between handset units arrives from the handset unit PS of the transmission source and the handset unit PS of the destination.
Are assigned to different communication channels, and these communication channels are connected to form a wireless communication link between the slave units.

The direct connection control means 53 between sub-units includes a sub-unit PS
When a call signal in the direct call mode between handset arrives from the terminal, a call channel is assigned to the calling handset PS, and an incoming call notification including a call mode switching instruction is sent to the called handset PS. After that, a wireless link using the above-mentioned communication channel is formed between the both handsets.

On the other hand, the slave unit PS includes a radio unit 6 having an antenna 61, a modem unit 7, a TDMA unit 8, and a communication unit 9.
And a control unit 10 including a key input unit 104 and a display unit 105.

That is, the radio frequency signal arriving from the master unit BS is received by the antenna 61 and then input to the receiving unit 63 via the high frequency switch 62 of the radio unit 6. In the receiving section 63, the received radio frequency signal is mixed with a receiving local oscillation signal generated from the frequency synthesizer 64 and frequency-converted into a receiving intermediate frequency signal.
The local oscillation frequency generated from the frequency synthesizer 64 is instructed by the control unit 10 according to the radio channel frequency. The wireless unit 6 is provided with a reception electric field strength detection unit 66. The reception field strength detection unit 66 detects the reception field strength of the radio frequency signal arriving from the master unit BS, and notifies the control unit 10 of the detected value.

The received intermediate frequency signal output from the receiving section 63 is input to the demodulating section 71 of the modem section 7. The demodulation section 71 digitally demodulates the received intermediate frequency signal, thereby reproducing a digital communication signal.

TDMA decoding section 81 of TDMA section 8
Extracts a digital communication signal from a time slot allocated to the own device according to an instruction from the control unit 10 and inputs the extracted digital communication signal to the communication unit 9. The communication unit 9 includes an adaptive difference PCM transcoder 91 and a PC
M codec 92, and the digital speech signal is transmitted by the adaptive differential PCM transcoder 91 and PCM
The signal is sequentially decoded by the codec 92 and reproduced into an analog call signal. The analog communication signal is amplified by a receiving amplifier (not shown) and then output from a speaker 93.

On the other hand, the transmission voice input to the microphone 94 is sequentially encoded by the PCM codec 92 and the adaptive difference PCM transcoder 91 to become a digital communication signal. In the TDMA encoding unit 82, the digital speech signal output from the adaptive difference transcoder 91 is inserted into a time slot specified by the control unit 10 and input to the modulation unit 72. In the modulator 72, the carrier signal is digitally modulated by the digital communication signal, and the modulated carrier signal is input to the transmitter 65. In the transmitting section 65, the modulated carrier signal is mixed with a transmitting local oscillation signal generated from the frequency synthesizer 64 to be frequency-converted to a radio channel frequency instructed by the control section 10, and further to a predetermined transmission power. Amplified to the level. Then, the transmitting unit 6
The radio frequency signal output from 5 is transmitted from the antenna 61 to the base station BS via the high frequency switch 62.

The control unit 10 includes, for example, a microcomputer as a main control unit. As a new control function related to direct communication between slave units, the communication mode switching control means 1
01, an inter-slave direct call transmission control means 102, and an inter-slave direct call reception control means 103.

When a call mode designating operation is performed on the key input section 104, the call mode switching control means 101 determines whether the designated call mode is the direct talk mode between the slave units or the relay talk mode between the slave units. It is determined whether there is.
Further, when a request for switching to the direct communication mode between child devices arrives from the parent device BS, the communication mode of the own device is switched from the relay communication mode between the child devices to the direct communication mode between the child devices. Further, after the end of the call in the direct talk mode between the slave units, and when the switch to the direct talk mode between the slave units is not performed within a predetermined time after the switching to the direct talk mode between the slave units is instructed from the master unit BS. Then, the call mode is returned to the inter-child-unit relay call mode.

The direct-call-to-child-unit calling control means 102 sets the direct-call-to-child-unit communication mode to the base station BS when a calling operation is performed in a state where the direct-call-to-child-unit communication mode is designated as the call mode. A link channel establishment request including the requested information is transmitted, and when a communication channel is designated by the base station BS, a paging process is performed on the destination handset using this communication channel.

In the stand-by state, when the incoming call notification signal including the request for switching to the direct communication mode between the handset units arrives from the base station BS in the standby state, the control means 103 controls the direct telephone call mode between the handset units. Incoming call control state, master BS
Sends a link channel establishment request to set a communication channel, and thereafter executes a process for forming a wireless link with the originating handset.

Next, the operation of the apparatus configured as described above will be described with reference to the sequence diagrams shown in FIGS. 3 and 4, and the flowcharts shown in FIGS. Suppose now that in the slave unit PS1, the speaker performs a direct communication mode between the slave units with the key input unit 104 so as to perform a direct talk between the slave units with the slave unit PS2, and then performs a call operation. Suppose. Then, after the control unit 5 recognizes the designation operation of the direct communication mode between the slave units, the slave unit PS1 detects the calling operation in step 5a as shown in FIG. A “link channel establishment request” signal including a request to switch to the direct communication mode between slave units is transmitted to the master unit BS.

On the other hand, when a "link channel establishment request" signal arrives from slave unit PS1, master unit BS determines whether or not this signal includes a request for switching to the direct talk mode between slave units. If this request is included, a "link channel assignment" signal including information indicating an empty communication channel and information for instructing switching to the direct communication mode between the slave units is returned to the slave unit PS1 as the transmission source. I do. At the same time, an incoming call notification signal including switching instruction information for switching to the direct communication mode between the child devices is transmitted to the child device PS2 of the destination.

When the above-mentioned "link channel assignment" signal arrives, the control unit 10 of the slave unit PS1 of the transmission source performs step 5c.
Then, the process proceeds to step 5d, where it is determined whether the switching instruction of the communication mode is an instruction to switch to the relay communication mode between the slave units or an instruction to switch to the direct communication mode between the slave units. If the result of this determination is that there is an instruction to switch to the direct communication mode between slave units, the process proceeds to step 5f, where the communication mode of the own device is switched to the direct communication mode between slave units. Thereafter, a calling process for direct connection between the slave units is executed.
If the switching instruction is for the inter-slave unit relay call mode, the call processing via the master unit BS is performed in step 5e while maintaining the own unit's call mode in the inter-slave unit relay call mode. continue.

On the other hand, as shown in FIG. 6, the slave unit PS2 of the called party monitors the incoming call in step 6a in the standby state, and in this state, when an incoming call notification signal arrives from the master unit BS, in step 6b. The contents of the mode switching instruction included in the incoming call notification signal are determined. As a result of this determination, if it is the direct communication mode between the slave units, the process proceeds to step 6d, where the communication mode of the own device is switched to the direct communication mode between the slave units, and then the incoming call processing for the direct connection between the slave units is performed. Execute. If the switching instruction is for the inter-slave relay call mode, in step 6c, the master unit B keeps its own call mode in the inter-slave relay call mode.
The incoming call processing via S is continued.

In the calling process and the incoming call process for the direct connection between the slave units, as shown in FIG. 3, first, the originating slave unit PS1 uses the control channel for the direct talk between the slave units to set the destination slave unit. A calling signal is sent to the machine PS2. Then, a synchronization signal for establishing synchronization is transmitted and received between the slave unit PS1 as the transmission source and the slave unit PS2 as the destination. When the synchronization is established, an incoming call notification is performed in the called handset PS2, and in this state, when the speaker of the called handset PS2 goes off-hook and responds, the called handset PS2 receives a call from the called handset PS2. A response signal is returned to the handset PS1, and thereafter, both handsets PS
1 and PS2 are connected via a communication channel for direct communication between slave units, and communication is possible.

Accordingly, in this state, as shown in FIG. 3, even if a calling operation for a relay call between handset units is performed in another handset unit PS3, and a "link channel establishment request" signal is transmitted, the master unit unit PS3 receives the signal. Since two or more available time slots remain in the BS, a communication channel can be allocated to the slave unit PS3 using the time slots.

The source and destination slave units PS1,
PS2 receives a mode switching instruction from the master unit BS,
As shown in FIG. 4, time counting is started by a timer from that point of time. If a communication link is not formed within a predetermined time, the timer expires and the communication mode of the own device is returned to the relay communication mode between slave units. . Further, even when the communication in the direct communication mode between the slave units is completed, the communication mode of the own device is returned to the relay communication mode between the slave units.

As described above, in the present embodiment, when a calling operation is performed in the slave unit PS1 in a state where the direct talk mode between the slave units is specified, the calling control including the request for switching to the direct talk mode between the slave units is performed. The base station BS transmits a signal to the base station BS, and upon receiving the switching request, the base station BS sends a control signal including a mode switching instruction to each of the slave station PS1 as the transmission source and the slave station PS2 as the destination, and each slave station PS1. , And PS2 are switched to the direct communication mode between the slave units, respectively, and the communication link in the direct talk mode between the slave units is not formed within a predetermined time after the switching instruction is received. When the communication in the mode ends, the communication mode of each of the slave units PS1 and PS2 is returned to the relay communication mode between the slave units.

Therefore, according to the present embodiment, the call mode of the called handset PS2 is automatically switched to the direct call mode between handset units at the time of notification of an incoming call. Eliminates the need to manually set the direct call mode between handset units. Therefore, no matter what communication mode is set for the child device of the called party, a direct telephone call can be made between the child devices regardless of the communication mode. Therefore, it is possible to increase the utilization rate of the direct call mode between the slave units, thereby enabling a number of extension telephone calls between the slave units at the same time.

In this embodiment, each of the slave units PS1, PS2
Is provided with a mode return control means, and when the mode switching is not completed within a certain time after the mode switching instruction is received from the base station BS and after the end of the call, the call mode is automatically returned to the inter-subunit relay call mode. I do. Therefore, the call mode is not set to the direct call mode between the slave units, and the call mode is not left. As a result, it is possible to always reliably respond to the outside-line incoming call notification from the master unit BS.

The present invention is not limited to the above embodiment. For example, in the above-described embodiment, only when a link channel establishment request signal accompanied by a request for switching the direct communication mode between slave units is transmitted from the slave unit, the master unit An instruction to switch to the direct talk mode is sent to switch the talk mode to the direct talk mode between handset units, but a link channel establishment request signal accompanied by a request for switching the relay talk mode between handset units is transmitted from the slave unit. Even if the request is made, if there is no vacant slot and the master unit cannot allocate a channel to this request, the master unit sends an instruction to switch to the direct talk mode between slave units to each of the source and destination slave units. In such a case, the communication mode may be switched to the direct communication mode between child devices. In this way, the call can be made in the direct call mode between the slave units regardless of the use condition of the master unit, so that the call completion rate for the extension call request between the slave units can be increased.

In addition, the control procedure and contents of the transmission control and the reception control of the slave unit, the configuration of the master unit and the slave unit, the type of the system, and the like can be variously modified without departing from the gist of the present invention. .

[0045]

As described above in detail, according to the present invention, when a calling operation is performed in a state where the direct communication mode between the sub-units is set in the transmission source sub-unit, the switching to the direct communication mode between the sub-units is performed. A transmission control signal including a switching request is transmitted to the master unit, and upon receipt of the switching request to the slave unit direct communication mode, the master unit instructs the destination slave station to switch to the slave unit direct communication mode. The communication mode is switched to the direct communication mode between the slave units by returning the response signal including the response signal including the instruction to switch the communication mode to the direct communication mode between the slave units. The mode is switched to the direct communication mode between slave units, and thereafter, a procedure for setting a wireless link between the slave station of the transmission source and the slave station of the destination is executed. In addition, when the switching to the direct communication mode between the slave units is not completed within a predetermined time after the instruction to switch to the direct communication mode between the slave units is received, and after the communication in the direct communication mode between the slave units is completed, the communication is performed. The mode is returned to the relay communication mode between slave units.

Therefore, according to the present invention, the setting and canceling of the direct communication mode between slave stations can be performed automatically without relying on manual operation, thereby increasing the utilization rate of the direct communication mode between slave stations, and It is possible to provide a mobile communication system in which a slave station can reliably receive an incoming call from an outside line.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing a configuration of a base unit of a digital cordless telephone device according to one embodiment of the present invention.

FIG. 2 is a circuit block diagram showing a configuration of a slave unit of the digital cordless telephone device according to one embodiment of the present invention.

FIG. 3 is a sequence diagram showing a connection procedure between handset units in a direct call mode between handset units in one embodiment of the present invention.

FIG. 4 is a sequence diagram showing a call termination procedure in a direct call mode between child devices according to an embodiment of the present invention.

FIG. 5 is a flowchart showing a procedure and contents of transmission control by the slave unit shown in FIG. 2;

FIG. 6 is an exemplary flowchart showing the procedure and contents of incoming call control by the slave unit shown in FIG. 2;

FIG. 7 is a sequence diagram showing a connection procedure between handset units in a relay call mode between handset units.

FIG. 8 is a sequence diagram showing a connection procedure between slave units in a conventional direct talk mode between slave units.

FIG. 9 shows a four-channel multiplex multicarrier TDMA-TD.
The figure for demonstrating a D system.

FIG. 10 is a diagram showing an example of a channel use state in the parent device.

[Explanation of symbols]

BS ... master unit PS ... slave unit 1 ... master unit wireless unit 2 ... master unit modem unit 3 ... master unit TDMA unit 4 ... master unit communication unit 5 ... master unit control unit 6 ... slave unit wireless unit 7: modem unit of slave unit 8: TDMA unit of slave unit 9: communication unit of slave unit 10: control unit of slave unit 11, 61 ... antenna 12, 62 ... high frequency switch 13, 63 ... receiving unit 14, 64 ... frequency Synthesizer 15, 65 Transmitter 16, 66 Received electric field strength detector (RSSI) 21, 71 Demodulator 22, 72 Modulator 31, 81 TDMA decoder 32, 82 TDMA encoder 41, 91 Adaptation Differential PCM transcoder (ADPC
M-TRANSCODER) 42, 92 PCM codec (PCM-CODEC) 43 Switch switch 93 Speaker 94 Microphone 51 External line connection control unit 52 Relay connection control unit between subunits 53 Direct connection control unit between subunits 101 ... call mode switching control means 102 ... direct call transmission control means between slave units 103 ... direct call reception control means between slave units 104 ... key input unit 105 ... display unit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-64-5236 (JP, A) JP-A-6-38265 (JP, A) JP-A 4-160848 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H04B ^7/ 24-7/26 H04M 1/725 H04Q 7/00-7/38

Claims (1)

(57) [Claims] 1. A master station connected to a wired communication line, and a plurality of slave stations connected to the master station via a wireless channel. TDD
Connection using the slave station and the slave station as the communication mode.
Relay between slave stations that enables communication by connecting between them via the master station
Communication mode and direct connection between slave stations to enable communication
A mobile communication system comprising a direct communication mode between the slave stations, the master station, when transmitting control signals including a request for switching to the direct communication mode between said slave station has arrived from the slave station, relative to child station Means for transmitting a response signal including an instruction to switch to the direct communication mode between slave stations, and a means for transmitting an incoming call control signal including an instruction to switch to the direct communication mode between slave stations to a destination slave station; and Each of the slave stations is provided with mode designation means for designating and inputting a direct communication mode between slave stations, and, when the direct communication mode between slave stations is designated by the mode designation means at the time of transmission, the slave station with respect to the master station. Means for transmitting a transmission control signal including a request to switch to the direct communication mode between the stations, and communication of the own station when a response signal including an instruction to switch to the direct communication mode between the slave stations is returned from the master station. Set the mode to <br / A means for switching from the inter-slave relay communication mode to the inter-slave direct communication mode, and a method for receiving an incoming control signal including an instruction to switch from the master station to the inter-slave direct communication mode in a standby state. A means for switching and setting the communication mode of the own station from the inter-slave relay communication mode to the inter-slave direct communication mode, and, with the inter-slave direct communication mode set, A direct connection control means for connecting between slave stations through a wireless channel for direct communication between slave stations according to a predetermined procedure, and a signal including an instruction to switch to the direct communication mode between slave stations is transmitted from the master station. If the mobile station does not shift to the direct communication between slave stations within a predetermined time from the arrival time, and if the direct communication between the slave stations is terminated, the communication mode of the own station is changed from the direct communication mode between the slave stations to the slave station. Restore to relay communication mode A mobile communication system comprising: a mode restoration control unit for setting a state in which the mobile station can respond to an incoming call from a master station.