JP2000286775A - Direct communication method between mobile stations in radio communication system and mobile station using the communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain direct communication between mobile stations according to the TDD system without requiring reference signal from a control station or the like without the need for intervention of a relay station. SOLUTION: This radio communication system has a relay station 2 with a plurality of speech channels and connected to a control station 1 and a plurality of mobile stations 3, 4 making radio communication with the relay station 2 according to the TDD system. In the case of direct communication between the mobile stations 3, 4 placed in a radio zone, the caller side mobile station 3 starts transmission in an optional timing and after the called party side mobile station 4 detects a frame synchronizing signal from this transmission signal, the transmission reception time slot is set up by matching a reception slot of the called party side mobile station 4 with a transmission slot of the caller side mobile station 3 so as to attain direct communication between the caller side mobile station 3 and called party side mobile station 4 without the need for intervention of the relay station 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time division duplex (hereinafter simply referred to as "TDD") system for direct communication between mobile stations in a privately owned wireless communication system of a government, a prefectural government, a municipal government or a company. The present invention relates to a method for direct communication between mobile stations in a wireless communication system, and a mobile station using the communication method.

[0002]

2. Description of the Related Art Wireless communication systems disclosed in JP-A-8-33024 and JP-A-9-84136 are known as devices that enable direct communication between mobile stations by the TDD system.

In such a wireless communication system,
A transmission / reception time slot for direct communication between slave units is determined by synchronizing with a control signal from the master unit.

In a radio communication system having a relay station and a base station, synchronization with a time slot of a continuously or intermittently transmitted downlink signal such as a broadcast signal from the base station and the relay station is required. Thus, the transmission / reception time slot for direct communication between mobile stations is determined.

[0005] Referring to FIG. 8, a description will be given of a synchronous control of a direct communication method between slave units in a conventional digital cordless telephone system. 8A and 8B show frame timings between the master unit and the slave unit. FIG. 8A shows a transmission / reception frame of the master unit, FIG. 8B shows a control signal from the master unit,
FIG. 4C shows the timing of a call signal from the calling handset.
FIG. 3D shows the transmission / reception frames of the called-side slave station waiting.

According to this method, a transmission / reception time slot between the slave units is established by adjusting the transmission / reception timing of the call between the slave units as the basic timing to the control signal from the master unit, and the direct communication between the slave units is established. Is possible.

When a base station or a relay station exists,
The master unit corresponds to a base station or a relay station, the slave unit corresponds to a mobile station, and a ringing tone (ring back tone: RBT) is generated in a higher station such as a control station. By transmitting the ringing tone to the calling side slave unit, the ringing tone is output to the calling side slave unit.

[0008]

However, according to such a conventional direct communication method between mobile stations, the synchronization with the time slots of the downlink signals continuously or intermittently transmitted from the base station and the relay station is performed. Requires a reference signal to be taken,
The mobile station needs to store the frame timing.

Further, when a mobile station moves in a zone, there is another problem that communication between the mobile stations cannot be performed until the mobile station stores a frame timing corresponding to a destination wireless zone.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide a wireless communication system which enables direct communication between mobile stations by a TDD system without a reference signal from a control station or the like. It is an object of the present invention to provide a direct communication method between mobile stations and a mobile station using the communication method.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a relay station having a plurality of communication channels and a plurality of mobile stations performing wireless communication in a TDD system using these communication channels. A method for direct communication between mobile stations in a wireless communication system, wherein a calling mobile station of the plurality of mobile stations communicates directly with a called mobile station of the plurality of mobile stations. When starting, the calling mobile station:
The transmission of the transmission signal to the called mobile station is started at an arbitrary timing, and the called mobile station detects a frame synchronization signal based on the transmission signal from the calling mobile station, and outputs the frame synchronization signal. By adjusting the timing of the receiving slot of the called mobile station to the transmitting slot of the calling mobile station, a transmission / reception time slot between the calling mobile station and the called mobile station is established. The direct communication is performed between the calling mobile station and the called mobile station without the relay station.

According to the present invention, direct communication between mobile stations can be performed by the TDD system without a reference signal from a control station or the like.

[0013]

According to the first aspect of the present invention, there is provided a relay station having a plurality of communication channels, and a plurality of mobile stations performing wireless communication in a TDD system using these communication channels. A direct communication method between mobile stations in a wireless communication system having: a calling mobile station among the plurality of mobile stations communicating directly with a called mobile station among the plurality of mobile stations. When starting, the calling mobile station starts outputting a transmission signal to the called mobile station at an arbitrary timing, and the called mobile station outputs a transmission signal from the calling mobile station. Based on the frame synchronization signal, based on the frame synchronization signal, by adjusting the timing of the reception slot of the called mobile station to the transmission slot of the calling mobile station, the calling mobile station and The transmission / reception time slot between the called mobile stations Is established, and direct communication is performed between the calling mobile station and the called mobile station without the intermediary of the relay station, so that the mobile station moves in the TDD system without a reference signal from a control station or the like. This has the effect of enabling direct communication between stations.

According to the second aspect of the present invention, the calling mobile station that starts direct communication with the called mobile station detects one or more carrier frequencies for which transmission has been permitted in advance, and detects the carrier frequency. It is determined whether or not the frequency is an empty carrier, and if it is determined that the carrier frequency is an empty carrier, a frame synchronization signal is added on the carrier frequency, and notification information is transmitted to a communication channel to which a voice signal is assigned. Is transmitted to the called mobile station at an arbitrary timing.

According to the third aspect of the present invention, when the calling mobile station continues to transmit a transmission signal including notification information to the called mobile station, the user of the calling mobile station Is notified that communication is not possible because a communication channel is currently established, so that the user of the calling mobile station can recognize that communication is currently impossible.

According to the fourth aspect of the present invention, when the called mobile station waiting for direct communication from the calling mobile station receives the transmission signal from the calling mobile station, the called mobile station changes the transmission signal. Demodulate to generate a demodulated signal, detect a frame synchronization signal from the demodulated signal, and, based on the frame synchronization signal,
The receiving slot of the called mobile station can be synchronized with the transmitting slot of the calling mobile station.

According to the fifth aspect of the invention, the called mobile station, after establishing a transmission / reception time slot with the calling mobile station, adds a frame synchronization signal on the currently used carrier frequency, Further, it has an effect that a transmission signal in which notification information is added to a communication channel to which a voice signal is assigned can be transmitted to the calling mobile station in a transmission slot synchronized with a reception slot of the calling mobile station.

According to the invention, the called mobile station establishes a transmission / reception time slot with the calling mobile station, and then uses the transmission slot synchronized with the reception slot of the calling mobile station. When transmitting a transmission signal to the calling mobile station,
Since the current transmission start is notified to the user of the called mobile station, the user of the called mobile station can recognize the current transmission start.

According to the invention described in claim 7, when the calling mobile station receives the transmission signal from the called mobile station, the calling mobile station demodulates the transmission signal to generate a demodulated signal. Detects the frame synchronization signal, decodes the voice signal in the communication channel based on the frame synchronization signal, and, instead of the notification information, transmits the transmission signal to which the voice signal from the own station is added, and transmits the transmission signal to the calling mobile station It has the effect of transmitting to

According to the eighth aspect of the present invention, since the notification information included in the speech channel is silent even if the speech is decoded, the mobile station receiving the speech channel does not output the speech. In addition, there is an effect that the user on the mobile station side does not feel discomfort due to this notification information.

According to the ninth aspect of the present invention, the notification information received from the calling mobile station includes ring tone information for generating an arbitrary ring tone, and the called mobile station transmits the call tone to the calling mobile station. A ring tone is generated based on the ring tone information included in the notification information received from the mobile station, and the ring tone is output as a ringing tone. The mobile station has the effect that a ringtone can be obtained.

According to the tenth aspect of the present invention, the called mobile station generates a ring tone by voice decoding the ring tone information included in the notification information in the communication channel from the calling mobile station. Since the ring tone is output as a ring tone, the called mobile station can obtain the ring tone without the intervention of a relay station or a control station.

According to the eleventh aspect of the present invention, the called mobile station that is outputting the ringing tone generates a ring tone that generates an arbitrary ring tone in a transmission slot synchronized with a reception slot of the calling mobile station. Since the notification information including the information is added to the transmission signal to the calling mobile station, the calling mobile station can obtain a ringing tone without any intervening relay station or control station. It has the action of:

According to the twelfth aspect of the present invention, the notification information received from the called mobile station includes ringing tone information for generating an arbitrary ringing tone, and the calling mobile station transmits the ringing tone to the called mobile station. A ringing tone is generated based on the ringing tone information included in the notification information received from the mobile station, and the ringing tone is output. Therefore, even if a relay station, a control station, or the like does not intervene, the calling side moves. The station has an effect that a ringing tone can be obtained.

According to the thirteenth aspect of the present invention, the calling mobile station generates a ringing tone by voice decoding the ringing tone information included in the notification information in the communication channel from the called mobile station. Since the ringing tone is output, the calling mobile station can obtain the ringing tone without the intervention of a relay station or a control station.

According to the fourteenth aspect of the present invention, the timing of the transmission slot of the called mobile station has a predetermined time length in the frame synchronization signal detected from the calling mobile station, and this time length Has the effect that the setting can be changed.

According to the fifteenth aspect of the present invention, there are provided a plurality of mobile stations capable of directly communicating with each other in a TDD system using a plurality of communication channels of a relay station, wherein the mobile station comprises:
When receiving a transmission signal for starting communication directly from a calling mobile station among the plurality of mobile stations, a frame synchronization signal of the calling mobile station is detected based on the transmission signal, and the frame synchronization signal is On the basis of, by adjusting the timing of the reception slot of the mobile station to the transmission slot of the calling mobile station, to establish a transmission and reception time slot with the calling mobile station, without the relay station, Since the direct communication with the calling mobile station is performed, there is an effect that direct communication can be performed between the mobile stations by the TDD method without a reference signal from a control station or the like.

According to the sixteenth aspect, the mobile station outputs the transmission signal by adding the notification information to the communication channel to which the voice signal is allocated, so that the mobile station obtains the information based on the notification information. be able to.

According to the seventeenth aspect of the present invention, the notification information added to the speech channel is made silent even when speech is decoded, so that the mobile station receiving this speech channel outputs the speech. However, there is an effect that the user on the mobile station side does not feel discomfort due to this notification information.

According to the eighteenth aspect of the present invention, when the mobile station receives the notification information from the calling mobile station, the mobile station generates a ring tone based on the ring tone information included in the notification information. Since the sound is output as a sound, the mobile station that has received the call can obtain a ring tone without the intervention of a relay station or a control station.

According to the nineteenth aspect, when the mobile station receives the notification information from the calling mobile station, the mobile station generates a ring tone by decoding the ring tone information included in the notification information. Since the ring tone is output as a ring tone, the mobile station that has received the call can obtain the ring tone without the intervention of a relay station or a control station.

According to the twentieth aspect, when the calling mobile station starts direct communication with another mobile station, the calling mobile station generates a ringing tone based on the ringing tone information included in the notification information. Since this ringing tone is output, the calling mobile station can obtain the ringing tone without the intervention of a relay station or a control station.

According to the twenty-first aspect of the present invention, when the calling mobile station starts direct communication with another mobile station, the calling tone information contained in the notification information is decoded by speech to make a ring tone. Is generated and this ringing tone is output.
There is an effect that the calling mobile station can obtain a ringing tone without the intervention of a relay station, a control station, or the like.

(Embodiment 1) Hereinafter, a radio communication system according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating an overall configuration of a wireless communication system according to a first embodiment, and FIG. 2 is a block diagram illustrating an internal configuration of a mobile station according to the first embodiment.

The radio communication system shown in FIG. 1 includes a control station 1 for setting and switching control of a communication channel, monitoring and controlling a relay station, monitoring and controlling a communication channel, and a plurality of communication stations connected to the control station 1. Relay station 2 having a communication channel of
And a plurality of mobile stations 3 and 4 capable of performing wireless communication with the relay station 2 by the TDD scheme and capable of directly communicating with each other.
It consists of:

In the wireless communication system having such a configuration, when performing direct communication between the mobile stations 3 and 4, for example, the mobile station 3 is a calling mobile station, and the mobile station 4 is connected to the called mobile station. Then, even if there is no intermittently transmitted control signal from the relay station 2, the called mobile station 4 adjusts the timing of the receiving slot to the transmitting slot of the calling mobile station 3 so that A transmission / reception time slot between the calling mobile station 3 and the called mobile station 4 is established.
This allows direct communication between the calling mobile station 3 and the called mobile station 4 without intervening. Hereinafter, the details will be described.

The calling mobile station 3 and the called mobile station 4 shown in FIG. 2 include a radio unit 5, a modem unit 6, a timing generation unit 7,
DSP (digital signal processing unit) 8, CPU (control unit)
9, a display / operation unit 10 and an audio unit 11.

The radio section 5 communicates with the relay station 2 or the partner mobile station through an antenna (not shown). The modulation / demodulation unit 6 performs logic processing of modulation / demodulation such as π / 4 shift QPSK. The timing generator 7 generates and supplies a timing signal to each of the modem 6, the DSP 8, the CPU 9, and the audio unit 11.

The DSP 8 performs time-division multiple access / duplex control, scramble, error control, ADPCM voice coding / decoding, and the like. In addition, the CPU 9
It controls the entire mobile station. These CPU 9 and DSP
8 allows direct communication between the calling mobile station 3 and the called mobile station 4 without interposition of the relay station 2.

The display / operation unit 10 includes a CPU 9
And various operations such as dial operation are performed, and LED or LC is displayed.
It is composed of a display unit such as D, a keyboard, and the like.

The audio section 11 includes a microphone for extracting an audio signal, an A / D converter for digitally converting the audio signal extracted by the microphone, and an amplifier for amplifying the digitally converted audio signal. A microphone amplifier to be input to the DSP 8, a D / A converter for converting an audio signal processed by the DSP 8 into an analog signal, a receiver amplifier for amplifying the analog-converted audio signal, and an amplified audio signal Is output by a receiver or the like that outputs the sound.

Next, a direct communication operation between the calling mobile station 3 and the called mobile station 4 in the first embodiment will be described. FIG. 3 is a sequence diagram showing a direct communication operation between the calling mobile station 3 and the called mobile station 4 in the first embodiment.

In this case, it is assumed that the calling mobile station 3 and the called mobile station 4 are located in a wireless zone where they can communicate with each other.

The CPU 9 of the calling mobile station 3 shown in FIG.
When a call operation from the display / operation unit 10 for starting direct communication with the called mobile station 4 is detected by press (step S1), one or more carrier frequencies for which transmission permission has been received in advance are detected. Then, it is determined whether or not this carrier frequency is an empty carrier, and when it is determined that this carrier frequency is an empty carrier, a transmission operation is instructed to the DSP 8 (step S2).

The DSP 8 of the calling mobile station 3 has a CPU
When receiving a transmission operation instruction from the mobile station 9, the called mobile station 4 adds a frame synchronization signal, a preamble signal, and the like to a carrier frequency determined to be an idle carrier, and further assigns a voice signal to a communication channel. It generates a transmission signal to which notification information decoded by an arbitrary audio decoding method that does not produce silence even when audio is decoded is added.

Further, the DSP 8 of the calling mobile station 3
Transmits the generated transmission signal as silent transmission to the called mobile station 4 in an arbitrary timing slot (step S3). At this time, the CPU 9 of the calling mobile station 3 displays on the display / operation unit 10 "Synchronization is in progress" to notify the user that a call cannot be made because synchronization is currently being established (step S4).

On the other hand, in the called mobile station 4 waiting,
When the CPU 9 detects the carrier frequency (step S5), the CPU 9 instructs the DSP 8 of the called mobile station 4 to receive the carrier frequency (step S6). According to the receiving operation, the DSP 8 of the called mobile station 4 continues the received frame synchronization acquisition processing until the frame synchronization signal is obtained (step S7).

The DSP 8 of the called mobile station 4 executes the reception frame synchronization acquisition processing in step S7 to demodulate the transmission signal as silent transmission from the calling mobile station 3, and performs frame synchronization from the demodulated signal. When the signal is acquired (step S8), the called mobile station 4 becomes the third slot of the time length determined by the frame synchronization signal, for example, of the four-slot communication channel from the first slot to the fourth slot. In the case where transmission and reception are performed in step (1), a waiting time until the first to third slots arrive, that is, a transmission timing time Xms of the third slot is calculated.

Further, the DSP 8 of the called mobile station 4
Is an arbitrary speech code that adds a frame synchronization signal, a preamble signal, or the like to the received carrier frequency and assigns a speech signal to a speech channel to which speech is not silenced even if speech is decoded by the calling mobile station 3. A transmission signal to which notification information encoded by the encoding scheme is added.

Here, the DSP 8 of the called mobile station 4
The transmission / reception between the calling mobile station 3 and the called mobile station 4 is performed by matching the transmission slot of the calling mobile station 3 with the reception slot of the called mobile station 4 based on the acquired frame synchronization signal. Establish frame synchronization by establishing time slots.

After the DSP 8 of the called mobile station 4 establishes frame synchronization with the calling mobile station 3, the DSP 8 waits for the next arriving transmission slot of the called mobile station 4. The timing time Xms is measured, and when the transmission timing time Xms is reached (step S9), the generated transmission signal is transmitted to the calling mobile station 3 as voice transmission in the transmission slot at this time (step S1).
0).

That is, the DSP 8 of the called mobile station 4 waits for a transmission timing time corresponding to the transmission slot of the called mobile station 4, and uses the transmission slot of the called mobile station 4 to transmit the transmission signal as voice transmission. Transmit to the mobile station 3.

When the CPU 9 of the called mobile station 4 establishes frame synchronization with the calling mobile station 3 and starts voice transmission, the user of the called mobile station 4 is currently receiving a call. Is displayed on the display / operation unit 10 (step S11).

When the DSP 8 of the calling mobile station 3 receives the voice transmission from the called mobile station 4, it executes this frame synchronization acquisition processing (step S12). The data is transmitted to the called mobile station 4 (step S13).

Upon receiving the silent transmission from the calling mobile station 3, the DSP 8 of the called mobile station 4 performs a frame detection process to determine whether or not the transmission matches the frame synchronization signal ( Step S14) One for each frame
The CPU 9 of the called mobile station 4 is notified of the frame pulse signal generated each time as a frame timing signal (FRT) (step S15).

The CPU 9 of the called mobile station 4 executes step S
If it is determined in step 14 that the frame synchronization signals match, the voice transmission from the called mobile station 4 to the calling mobile station 3 is continued (step S16).

The DSP 8 of the calling mobile station 3
Indicates that the frame synchronization is acquired in the frame synchronization acquisition processing continued in step S12 (step S1).
7) Waiting for a transmission timing time Xms corresponding to the transmission slot of the own station from the frame synchronization signal (step S18), and switching from silent transmission to voice transmission,
Voice transmission to the called mobile station 4 is started in the transmission slot of the calling mobile station 3 (step S19). Here, the DSP 8 of the calling mobile station 3 calculates the transmission timing time Xms until the transmission slot of the calling mobile station 3 arrives in the same manner as described above.

Thus, direct communication by voice transmission between the calling mobile station 3 and the called mobile station 4 becomes possible.

The calling mobile station 3 is connected to the called mobile station 4.
When the voice transmission to the DSP 8 is started, the DSP 8
9 is notified of a synchronization establishment signal (FSYNC) and a frame timing signal (FRT) (step S21). In response to the synchronization establishment signal and the frame timing signal, the CPU 9 cancels the display of “synchronization established (silent transmission in progress)” currently being displayed on the display / operation unit 10 (step S22), thereby making a call. The user of the local mobile station 3 is made aware that the call with the called mobile station 4 has become possible.

Next, the DS in the first embodiment will be described.
The temporal state transition of P8 will be described. FIG. 4 shows the first
FIG. 10 is a time state transition diagram of the DSP 8 in the embodiment.

As shown in FIG. 4, state 12 is the initialization of the signal processing unit in the DSP 8, and after the frame synchronization is established, the time length determined from the frame synchronization signal, that is, from the received frame synchronization signal, is automatically set. It is assumed that various variable setting values such as a transmission timing time Xms corresponding to the transmission slot of the station are set, and as shown in FIG. I have.

The various variable setting values are written from the display / operation unit 10 via the CPU 9 to a non-volatile memory such as an EEPROM (not shown) connected to the CPU 9 and necessary values are initialized by the DSP 8 Is set by

After the initialization is completed, the DSP 8 shifts to an interrupt waiting state 13 for waiting for a so-called call or call operation. When there is a transmission instruction during the interrupt waiting state 13, this is a function of the DSP 8 operating on the calling mobile station 3, and the DSP 8 shifts to the silent transmission state 14.

The DSP 8 in the silent transmission state 14
Determines whether or not a time corresponding to one frame (hereinafter, simply referred to as one frame length) has elapsed, and if one frame length has elapsed, obtains reception frame synchronization in order to obtain reception frame synchronization. Move to state 15. In the reception frame synchronization acquisition state 15, the silent transmission state 14 and the TDD operation are repeatedly executed until the reception frame synchronization is acquired.

If the reception frame synchronization has been acquired in the reception frame synchronization acquisition state 15, the operation shifts to the audio transmission state 16 in which the silent transmission is switched to the audio transmission. After the transition to the voice transmission state 16, the state transitions to the reception frame synchronization detection state 17 for detecting whether or not the reception frame synchronization matches.

In the reception frame synchronization detection state 17,
When it is detected that the frame synchronization received by an arbitrary algorithm is lost, the process shifts to the initialization state 12 again, executes the initialization of the DSP 8, and waits in the interrupt waiting state 13.

Although not shown in FIG. 4, the CPU 9
It is also possible to shift to the initialization state 12 after executing the call termination processing from.

When a reception instruction is issued during the interruption waiting state 13, the DS operating on the called mobile station 4
This function is a function of P8. The DSP 8 detects an empty carrier in response to the reception instruction, and when detecting the empty carrier, shifts to a reception frame synchronization acquisition state 18 in order to acquire reception frame synchronization.

The received frame synchronization acquisition state 1
At 8, the process is continued until the reception frame synchronization is obtained. If the received frame synchronization is acquired in the received frame synchronization acquisition state, after the acquisition of the frame synchronization, the state shifts from the synchronized frame to the Xms waiting state 19 for waiting for the transmission timing time Xms corresponding to the transmission slot of the own station. .

If the transmission timing time Xms has been reached, a transition is made to the voice transmission state 20 in which voice transmission is executed in the transmission slot at this time.

In the voice transmission state 20, it is determined whether or not one frame length has elapsed. If the one frame length has elapsed, a reception frame synchronization detection state for detecting whether or not the reception frame synchronization is matched. Move to 21.

When the reception frame synchronization detection state 21 detects that the reception frame synchronization is matched by an arbitrary algorithm, the voice transmission state 20 and the TDD operation are continued. Further, when it is detected in the reception frame synchronization detection state 21 that the reception frame is out of synchronization, the processing shifts to the initialization state 12 again, and the DSP 8 is initialized.
It will wait in the interrupt waiting state 13.

As described above, according to the first embodiment, the relay station 2 having a plurality of communication channels and the plurality of mobile stations 3 and 4 performing wireless communication in the TDD system using these communication channels are provided. When the calling mobile station 3 starts direct communication with the called mobile station 4, the calling mobile station 3 transmits a transmission signal to the called mobile station 4 at an arbitrary timing. Output starts, the called mobile station 4 detects a frame synchronization signal based on a transmission signal from the calling mobile station 3, and based on the frame synchronization signal, the called mobile station 3 By adjusting the timing of the reception slot of the called mobile station 4 to the transmission slot of the called mobile station 3,
Since the transmission / reception time slot between the called mobile station 4 and the called mobile station 4 is established, the direct communication between the calling mobile station 3 and the called mobile station 4 is performed without the relay station 2 interposed therebetween. The mobile stations can directly communicate with each other by the TDD method without a reference signal from the control station 1 or the like.

The calling mobile station 3 is connected to the called mobile station 4.
When silence transmission is continued, it is displayed that the call cannot be made because the call channel is currently established.
D is displayed, so that the user of the calling mobile station 3 can recognize that a call cannot be made at present.

Also, the called mobile station 4 is
After establishing a transmission / reception time slot with the transmission side, a transmission signal is transmitted to the calling side mobile station 3 in a transmission slot synchronized with the reception slot of the calling side mobile station 3. Since the incoming call from the mobile station 3 is displayed on the LCD of the display / operation unit 10, the user of the called mobile station 4 can recognize the incoming call from the calling mobile station 3 at the start of transmission.

In the above embodiment, when the calling mobile station 3 continues the silent transmission to the called mobile station 4, the display / operation unit 10 of the calling mobile station 3 Although the LCD indicates that a call cannot be made because a communication channel is currently established, a blinking display or a lighting display of an LED may be used instead. Also, the indication of the transmission start of the called mobile station 4 can be replaced by the blinking display or the lighting display of the LED similarly to the above.

(Embodiment 2) Next, a radio communication system according to a second embodiment will be described. Note that the same reference numerals are given to the same components as those in the wireless communication system shown in the first embodiment, and the description of the configuration and operation is omitted.

The difference from the wireless communication system shown in the first embodiment is that the wireless communication system does not go through the relay station 2 or the control station 1
Each mobile station can output a ring tone (RTB) and a ring tone.

Next, a direct communication operation between the calling mobile station 3 and the called mobile station 4 in the second embodiment will be described. FIGS. 5 and 6 are sequence diagrams showing a direct communication operation between the calling mobile station 3 and the called mobile station 4 in the second embodiment.

The CPU 9 of the calling mobile station 3 shown in FIG.
When the call detection operation of the display / operation unit 10 for starting the direct communication with the called mobile station 4 is detected by press (step S31), one or more carrier frequencies for which transmission is permitted in advance are detected. It is determined whether or not this carrier frequency is an empty carrier, and when it is determined that this carrier frequency is an empty carrier, a transmission operation is instructed to the DSP 8 (step S32).

The DSP 8 of the calling side mobile station 3 adds a frame synchronization signal, a preamble signal, and the like to the carrier frequency determined to be an empty carrier, and further receives an incoming call on a speech channel to which a voice signal is assigned. The transmission signal added with the notification information decoded by an arbitrary audio decoding method that does not produce a silent sound even when the audio is decoded by the mobile station 4 is sent to the called mobile station 4 at an arbitrary timing slot as a silent transmission. It transmits (step S33). At this time, "Synchronization is being established" is displayed on the display / operation unit 10 of the calling mobile station 3 (step S34).

On the other hand, in the called mobile station 4 waiting,
When the CPU 9 detects the carrier frequency (step S35), the CPU 9 instructs the DSP 9 of the called mobile station 4 to receive the carrier frequency (step S36). According to the receiving operation, the DSP 8 of the called mobile station 4 continues the received frame synchronization acquisition processing until the frame synchronization signal is obtained (step S37).

The DSP 8 of the called mobile station 4 executes the reception frame synchronization acquisition processing in step S37, and demodulates the transmission signal as silent transmission from the calling mobile station 3,
A frame synchronization signal is obtained from the demodulated signal (step S38).

Here, the DSP 8 of the called mobile station 4
Is stored in the transmission slot of the calling mobile station 3 based on the frame synchronization signal acquired in step S38.
By establishing a transmission / reception time slot between the calling mobile station 3 and the called mobile station 4 by matching the reception slots of
Establish frame synchronization.

The CPU 9 of the called mobile station 4
When the frame synchronization with the calling mobile station 3 is established, "incoming" is displayed on the display / operation unit 10 to notify the user of the called mobile station 4 that the incoming call is currently being received (step S39). ), The audio section 11 is turned on to output a ring tone (RT) (step S40).

Further, the DSP 8 of the called mobile station 4
Generates a transmission signal in which a frame synchronization signal, a preamble signal, and the like are added to a received carrier frequency, and the ring tone (RT) is added as ringing tone information to a communication channel to which a voice signal is assigned.

The DSP 8 of the called mobile station 4 waits for the next arriving transmission slot of the called mobile station 4 after the frame synchronization with the calling mobile station 3 is established. After measuring the time Xms and reaching the transmission timing time Xms (step S41), the generated transmission signal is transmitted to the calling mobile station 3 as RT transmission in the transmission slot at this time (step S4).
2).

Upon receiving the RT transmission from the called mobile station 4, the DSP 8 of the calling mobile station 3 executes this frame synchronization acquisition processing (step S43). The message is transmitted to the called mobile station 4 (step S44).

Upon receiving the silent transmission from the calling mobile station 3, the DSP 8 of the called mobile station 4 executes a frame detection process to determine whether or not the transmission matches the frame synchronization signal ( Step S45) 1 for each frame
The frame pulse signal generated each time is notified to the CPU 9 of the called mobile station 4 as a frame timing signal (FRT) (step S46).

The DSP 8 of the called mobile station 4 executes step S
If it is determined in the frame detection process of step 45 that the frame synchronization signals match, the RT transmission from the called mobile station 4 to the calling mobile station 3 is continued (step S47).
At this time, the CPU 9 of the called mobile station 4 starts the operation of counting the press detection waiting timer for detecting the off-hook operation (step S48).

The DSP 8 of the calling mobile station 3
Indicates that the frame synchronization is acquired in the frame synchronization acquisition processing continued in step S43 (step S4).
9) Waiting for a transmission timing time Xms corresponding to the transmission slot of the own station from this frame synchronization signal (step S50), and switching from silent transmission to voice transmission,
Voice transmission to the called mobile station 4 is started in the transmission slot of the calling mobile station 3 (step S51). Here, the DSP 8 of the calling mobile station 3 calculates the transmission timing time Xms until the transmission slot of the calling mobile station 3 arrives in the same manner as described above.

Thus, direct communication by voice transmission between the calling mobile station 3 and the called mobile station 4 becomes possible.

The calling mobile station 3 is connected to the called mobile station 4.
When the voice transmission to the DSP 8 is started, the DSP 8
9 is notified of a synchronization establishment signal (FSYNC) and a frame timing signal (FRT) (step S52). In response to the synchronization establishment signal and the frame timing signal, the CPU 9 cancels the display of “synchronization established (silent transmission in progress)” currently being displayed on the display / operation unit 10 (step S53), thereby making a call. The user of the local mobile station 3 is made aware that the call with the called mobile station 4 has become possible.

Further, when voice transmission to the called mobile station 4 is started, the calling mobile station 3 voice-decodes a transmission signal as RT transmission from the called mobile station 4. As a result, a ringing tone (RBT) is output as audio via the audio unit 11 (step S54).

Then, the called mobile station 4 continues the RT transmission to the calling mobile station while outputting the ringing tone, and also monitors the off-hook operation. On the other hand, the calling side mobile station 3 decodes the RT transmission from the called side mobile station by voice decoding, thereby generating a ring tone (RBT).
, And voice transmission for calling to the called mobile station is continued. That is, as shown in FIGS. 5 and 6, voice transmission and RT transmission are repeatedly performed between the calling mobile station 3 and the called mobile station 4.

Thereafter, the CPU 9 of the called mobile station 4
When an off-hook operation is detected by pressing, a voice switching instruction is issued by D
Notify SP8 (step S55). This DSP8
Switches from RT transmission to voice transmission in response to the voice switching instruction, and shifts to voice transmission processing from the next frame (step S56).

The calling side mobile station 3 decodes the voice transmission instead of the RT transmission from the called side mobile station 4 (step S57), and thereby the calling side mobile station 3 and the called side. Direct communication between the mobile stations 4 becomes possible.

As described above, in response to the silent transmission from the calling mobile station 3, the called mobile station 4 sounds a ring tone, and furthermore, the ring tone of the called mobile station 4 is encoded to perform RT transmission. Is transmitted to the calling mobile station 3 and the ring tone is output as voice by decoding the RT transmission of the calling mobile station 3 by voice. Therefore, even if the relay station 2 or the like does not intervene, The user of the calling mobile station 3 can be provided with a ring tone, and the user of the called mobile station 4 can be provided with a ring tone.

Next, the DS in the second embodiment will be described.
The temporal state transition of P8 will be described. FIG. 7 shows the second
FIG. 10 is a time state transition diagram of the DSP 8 in the embodiment.

As shown in FIG. 7, the state 22 is the initialization of the signal processing unit in the DSP 8, and after the frame synchronization is established, the time length determined from the frame synchronization signal, that is, from the received frame synchronization signal, is automatically set. It is assumed that various variable setting values such as the transmission timing time Xms corresponding to the transmission slot of the station are set, and as shown in FIG. 7, the configuration is such that initialization is performed by a signal such as reset release or frame synchronization loss. I have.

The various variable setting values are written from the display / operation unit 10 via the CPU 9 to a nonvolatile memory such as an EEPROM (not shown) connected to the CPU 9 and necessary values are initialized by the DSP 8 Is set by

After completion of the initialization, the DSP 8 shifts to an interrupt waiting state 23 for waiting for a so-called incoming call or calling operation. If there is a transmission instruction during the interrupt waiting state 13, this is a function of the DSP 8 operating in the calling mobile station 3, and the DSP 8 shifts to the silent transmission state 24.

The DSP 8 in the silent transmission state 24
Determines whether or not a time corresponding to one frame (hereinafter, simply referred to as one frame length) has elapsed, and if one frame length has elapsed, obtains reception frame synchronization in order to obtain reception frame synchronization. Move to state 25. In the reception frame synchronization acquisition state 25, the silent transmission state 14 and the TDD operation are repeatedly executed until the reception frame synchronization is acquired.

If the reception frame synchronization has been acquired in the reception frame synchronization acquisition state 25, a transition is made to the audio transmission state 26 in which the silent transmission is switched to the audio transmission. After shifting to the voice transmission state 26, the process shifts to a reception frame synchronization detection state 27 for detecting whether or not the reception frame synchronization is matched.

In the received frame synchronization detection state 27,
When it is detected that the frame synchronization received by an arbitrary algorithm is out of synchronization, the process again shifts to the initialization state 22, executes the initialization of the DSP 8, and waits in the interrupt waiting state.

Although not shown in FIG. 7, the CPU 9
It is also possible to shift to the initialization state 12 after executing the call termination processing from.

When a reception instruction is issued during the interruption waiting state 23, the DS operating on the called mobile station 4
This function is a function of P8. The DSP 8 detects an empty carrier in response to the reception instruction, and when detecting an empty carrier, shifts to a reception frame synchronization acquisition state 28 in order to acquire reception frame synchronization.

Then, this received frame synchronization acquisition state 2
At 8, the process is continued until the reception frame synchronization is obtained. If the reception frame synchronization is acquired in the reception frame synchronization acquisition state 28, after the acquisition of the frame synchronization, the state shifts from the synchronized frame to the Xms waiting state 29 for waiting for the transmission timing time Xms corresponding to the transmission slot of the own station. I do.

If the transmission timing time Xms has been reached, RT transmission state 3 in which a ring tone is voice-coded in the transmission slot at this time to perform RT transmission as a ring tone.
Move to 0.

In the RT transmission state 30, it is determined whether or not one frame length has elapsed. If the one frame length has elapsed, a reception frame synchronization detection state for detecting whether or not the reception frame synchronization is matched. Move to 31.

When the reception frame synchronization detection state 31 detects that the reception frame synchronization is matched by an arbitrary algorithm, the RT transmission state 20 and the TDD operation are continued. Further, when it is detected in the reception frame synchronization detection state 31 that the reception frame is out of synchronization, the process again shifts to the initialization state 12, and the DSP 8 is initialized.
It will wait in the interrupt waiting state 23.

When the off-hook operation of the called mobile station 4 is detected during the reception frame synchronization detection state 31, this RT
The transmission is switched to the voice transmission, and the state shifts to the voice transmission state 32.

After the transition to the voice transmission state 32, the flow shifts to the reception frame synchronization detection state 31 to detect whether or not the frame synchronization is established, and repeat the voice transmission and the TDD operation in the ringing tone transmission state 30. . Then, when it is detected that the frame synchronization has been lost by an arbitrary algorithm, the process returns to the initialization state 22 to initialize again.
It waits for the state 23 interrupt.

According to the second embodiment, when direct communication is performed between the calling mobile station 3 and the called mobile station 4, the call is received in response to the silent transmission from the calling mobile station 3. The mobile station 4 rings a ring tone and decodes the ring tone of the called mobile station 4 to transmit an RT transmission to the calling mobile station 3, and the RT transmission of the calling mobile station 3. Is output as a ringing tone by decoding the voice, so that the ringing tone is provided to the user of the calling mobile station 3 without the intervention of the relay station 2 or the like, and the called mobile station is called. 4 users can be provided with ringtones.

Further, since the CPU 9 of the called mobile station 4 switches from the RT transmission to the voice transmission in accordance with the off-hook operation, even if the relay station 2 or the control station 1 does not intervene, the mobile station can communicate with each other. A direct communication like a telephone becomes possible between them.

The ringing tone is decoded and sounded by the voice encoding unit of the called mobile station 4 so that the called mobile station 4 simultaneously sounds the ringing tone, or the ringing tone to be transmitted is transmitted. Alternatively, another ring tone may be directly sounded from the sound source generator.

[0117]

As is apparent from the above description, according to the present invention, regardless of the presence or absence of a master station or a control station, a TDD system in which it is difficult to constantly or intermittently transmit a control signal serving as a time slot reference. In a wireless communication system, direct communication between mobile stations can be performed by the TDD method without a reference signal from a control station or the like, and accordingly, a time slot reference is transmitted to a calling mobile station that starts transmission. And a direct communication method between mobile stations can be provided, and even in direct communication between mobile stations, a ring tone and a ringing tone can be provided to each mobile station.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a wireless communication system according to a first embodiment of a direct communication method between mobile stations according to the present invention;

FIG. 2 is a block diagram showing an internal configuration of a mobile station according to the first embodiment.

FIG. 3 is a sequence diagram showing a direct communication operation between mobile stations according to the first embodiment.

FIG. 4 is a state transition diagram over time of the DSP according to the first embodiment;

FIG. 5 is a sequence diagram showing a direct communication operation between mobile stations according to the second embodiment.

FIG. 6 is a sequence diagram showing a direct communication operation between mobile stations according to the second embodiment.

FIG. 7 is a diagram illustrating a temporal state transition of a DSP according to the second embodiment;

FIG. 8 is a timing chart of a direct communication method between slave units in a conventional digital cordless telephone.

[Explanation of symbols]

 Reference Signs List 1 control station 2 relay station 3 calling side mobile station (mobile station) 4 called side mobile station (mobile station) 5 radio section 6 modem section 7 timing generation section 8 DSP (digital signal processing section) 9 CPU (control section) 10 Display / operation unit 11 Audio unit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5K067 AA25 AA34 AA35 BB12 CC05 DD02 DD13 DD23 DD25 EE02 EE06 EE25 FF15 FF27 GG03 GG11 HH01 JJ03

Claims (21)

[Claims] A relay station having a plurality of traffic channels;
A direct communication method between mobile stations in a wireless communication system having a plurality of mobile stations performing wireless communication in a TDD system using these communication channels, wherein a calling mobile station among the plurality of mobile stations is When starting direct communication to a called mobile station of the plurality of mobile stations, the calling mobile station starts outputting a transmission signal to the called mobile station at an arbitrary timing, The called mobile station,
A frame synchronization signal is detected based on the transmission signal from the calling mobile station, and the timing of the reception slot of the called mobile station is set to the transmission slot of the calling mobile station based on the frame synchronization signal. Together, a transmission / reception time slot between the calling mobile station and the called mobile station is established, and direct communication between the calling mobile station and the called mobile station without intervening the relay station. Direct communication method between mobile stations in a wireless communication system. 2. A calling mobile station that starts direct communication with a called mobile station detects one or more carrier frequencies for which transmission has been permitted in advance, and determines whether the carrier frequency is an empty carrier. If the carrier frequency is determined to be an empty carrier, a frame synchronization signal is added on the carrier frequency, and a transmission signal in which notification information is added to a communication channel to which a voice signal is assigned is transmitted at an arbitrary timing. 2. The direct communication method between mobile stations in a wireless communication system according to claim 1, wherein the transmission is performed to the called mobile station. 3. When a calling mobile station continues to transmit a transmission signal including notification information to a called mobile station, a call channel is currently established for a user of the calling mobile station. 3. The direct communication method between mobile stations in a wireless communication system according to claim 2, wherein the communication is notified that the communication is impossible. 4. The called mobile station waiting for direct communication from the calling mobile station receives the transmission signal from the calling mobile station and demodulates the transmission signal to generate a demodulated signal. ,
A frame synchronization signal is detected from the demodulated signal, and a reception slot of the called mobile station is synchronized with a transmission slot of the calling mobile station based on the frame synchronization signal. 4. The direct communication method between mobile stations in the wireless communication system according to 3. 5. A communication channel to which a called mobile station establishes a transmission / reception time slot with a calling mobile station, adds a frame synchronization signal to a currently used carrier frequency, and further allocates a voice signal. 5. The mobile station according to claim 4, wherein a transmission signal to which notification information is added is transmitted to the calling mobile station in a transmission slot synchronized with a reception slot of the calling mobile station. A direct communication method between each other. 6. The called mobile station, after establishing a transmission / reception time slot with the calling mobile station, transmits to the calling mobile station in a transmission slot synchronized with a reception slot of the calling mobile station. 6. The direct communication method between mobile stations in a wireless communication system according to claim 5, wherein when the signal is transmitted, the user of the called mobile station is notified of the current transmission start. 7. When a calling mobile station receives a transmission signal from a called mobile station, the calling mobile station demodulates the transmission signal to generate a demodulated signal, and detects a frame synchronization signal from the demodulated signal. Based on the frame synchronization signal, the audio signal in the communication channel is decoded, and instead of the notification information,
7. The direct communication method between mobile stations in a wireless communication system according to claim 5, wherein a transmission signal to which a voice signal from the own station is added is transmitted to the calling mobile station. 8. The direct communication method between mobile stations in a wireless communication system according to claim 2, wherein the notification information included in the communication channel is silent even if the speech is decoded. 9. The notification information received from the calling mobile station includes:
The called mobile station has ringtone information for generating an arbitrary ringtone, and the called mobile station generates a ringtone based on the ringtone information included in the notification information received from the calling mobile station. 8. The method for direct communication between mobile stations in a wireless communication system according to claim 2, wherein 10. The called mobile station generates a ring tone by voice decoding the ring tone information included in the notification information in the communication channel from the calling mobile station, and outputs the ring tone. The direct communication method between mobile stations in a wireless communication system according to claim 9, wherein 11. The called mobile station that is outputting a ringing tone is:
A transmission slot synchronized with a reception slot of the calling mobile station, wherein notification information including ringing tone information for generating an arbitrary ringing tone is added to a transmission signal to the calling side mobile station. 11. The direct communication method between mobile stations in the wireless communication system according to 10. 12. The notification information received from the called mobile station includes ringing tone information for generating an arbitrary ringing tone, and the calling mobile station transmits the notification information received from the called mobile station. A ringing tone is generated based on the ringing tone information included, and the ringing tone is output.
Or a direct communication method between mobile stations in the wireless communication system according to 9 to 11. 13. The calling mobile station generates a ringing tone by decoding the ringing tone information included in the notification information in the communication channel from the called mobile station, and outputs the ringing tone. 13. The direct communication method between mobile stations in a wireless communication system according to claim 12, wherein: 14. The transmission slot timing of the called mobile station has a time length determined by a frame synchronization signal detected from the calling mobile station, and the time length can be set and changed. The direct communication method between mobile stations in a wireless communication system according to claim 4, wherein 15. A plurality of mobile stations capable of directly communicating with each other in a TDD system using a plurality of communication channels of a relay station, wherein the mobile station is a calling side of the plurality of mobile stations. Upon receiving a transmission signal for starting direct communication from the mobile station, the mobile station detects a frame synchronization signal of the calling mobile station based on the transmission signal, and based on the frame synchronization signal, transmits a transmission signal of the calling mobile station. By adjusting the timing of the reception slot of the mobile station to the slot, a transmission / reception time slot with the calling mobile station is established, and the direct communication with the calling mobile station is performed without interposition of the relay station. A mobile station characterized by performing. 16. The mobile station according to claim 15, wherein the mobile station outputs a transmission signal by adding notification information to a communication channel to which a voice signal is assigned. 17. The notification information added to the call channel includes:
2. The apparatus according to claim 1, wherein even if the audio is decoded, no sound is generated.
6. The mobile station according to 6. 18. The mobile station, upon receiving the notification information from the calling mobile station, generates a ringtone based on the ringtone information included in the notification information, and sounds and outputs the ringtone. The mobile station according to claim 16, wherein 19. Upon receiving the notification information from the calling mobile station, the mobile station generates a ring tone by voice decoding the ring tone information included in the notification information, and outputs the ring tone. 19. The mobile station according to claim 18, wherein 20. When a calling mobile station starts direct communication with another mobile station, the calling mobile station generates a ringing tone based on ringing tone information included in the notification information, and outputs the ringing tone. The mobile station according to claim 16, characterized in that: 21. When a calling mobile station starts direct communication with another mobile station, the calling mobile station generates a ringing tone by decoding the ringing tone information included in the notification information, and generates the ringing tone. The mobile station according to claim 20, wherein the mobile station outputs the signal.