JP3486558B2 - Wireless voice multiplex communication terminal - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless voice multiplex communication terminal device and a wireless system for transmitting a media multiplex signal including an information frame including real time information such as voice and an information frame including non real time information such as computer data. The present invention relates to a voice multiplex communication system.

[0002]

2. Description of the Related Art A conventional technique relating to the transmission of a media multiplex signal composed of an information frame containing real-time information such as voice and an information frame containing non-real-time information such as computer data is disclosed in, for example, Japanese Unexamined Patent Publication No. 8-163071. It is disclosed in Japanese Patent Publication No. 9-219684.

For example, PHS (Personal Handy Phone Sys)
In the case of transmitting information using a wireless communication line such as tem), the probability of error occurrence is higher than that of a wired transmission line. Therefore, especially in the case of transmitting a media multiplex signal, a means for synchronizing the information frames between the terminals communicating with each other is required. A HDLC (High level Data Link Control p
rocedure) etc., add a unique flag,
Furthermore, considering the error in the flag, FEC is added to the flag part.
A method of applying (Forward Error Correction) and interleaving and transmitting is known.

According to this method, since the flag portion is protected, the synchronization is not lost. However, when FEC is applied to the encoded data itself, there is a problem that the effective transmission band is reduced. Also, if wrong synchronization occurs in the flag portion, different media will be passed to an unauthorized decoder. For example,
When transmitting a media multiplex signal in which voice information and computer data are mixed, if the computer data is erroneously passed to the voice decoder, noise may be generated. In particular, when transmission errors occur continuously, it is impossible to suppress noise generation.

On the other hand, PIAFS (PHS Internet Access)
Forum Standard) In protocols for data transmission such as procedures, fixed length frames are used for transmission, unique words for synchronization establishment are mutually transmitted at the time of link establishment, and after synchronization pull-in is completed, a fixed position is set at a specific position of the fixed length frame. By monitoring the presence / absence of a certain frame identification flag, the terminals communicating with each other are synchronously monitored, and if a transmission error occurs, error free is guaranteed by retransmission.

However, in the method such as the PIAFS procedure, when transmitting coded data such as voice, even if a non-fatal 1-bit error occurs during voice reproduction, the voice coded data is discarded. Moreover, since the transmission error is compensated by the retransmission, the delay caused by the retransmission control becomes a problem. Therefore, for example, in Japanese Patent Laid-Open No. 9-219684, error-free compensation is performed by using retransmission for computer data and images at the time of media multiplex transmission, and errors are allowed for real-time media such as voice to allow real-time performance. After completing the synchronization pull-in by compensating for each other and transmitting the unique words for synchronization establishment to each other at the time of link establishment,
The control is performed so that the transmission / reception timing of the fixed length frame is used.

However, even when the method disclosed in Japanese Patent Laid-Open No. 9-219684 is adopted, it is not possible to suppress noise, which is a problem when errors occur continuously. Further, if the transmission quality is poor and the link once established cannot be maintained, the communication state cannot be restored to the normal state.

[0008] For example, in the PIAFS procedure, after the unique word is pulled in and synchronization is established, the presence or absence of the synchronization identification flag is monitored at a fixed byte position. Assuming that the pulled-in synchronization is lost, the process transitions to the processing for pulling in the synchronization again. However, when transmitting media such as voice, it is desirable to allow some errors and continue decoding on the receiving side to reduce voice interruptions. However, if the received data is passed to the audio decoder in a state of being out of synchronization, data that is not actually voice encoded data may be passed to the audio decoder, which is expected to cause noise.

[0009]

SUMMARY OF THE INVENTION In order to minimize the overhead at the time of multiplex transmission of media, Japanese Patent Laid-Open No. 9-2 is recommended.
As disclosed in Japanese Patent Publication No. 196884, it is desirable to identify media in synchronization with each other between terminals communicating with each other at a predetermined timing. Further, it is necessary to suppress as much as possible noise that occurs when transmission conditions are so bad that synchronization cannot be maintained.

Particularly, in the case of communicating using a wireless communication means such as PHS, it is necessary to cope with a momentary interruption occurring in a wireless section and a communication line interruption due to a base station switching operation (handover). The present invention occurs in a wireless section in a wireless voice multiplex communication terminal device and a wireless voice multiplex communication system that perform media multiplex transmission in synchronization with a predetermined timing without using a synchronization flag after pulling in synchronization. Out-of-sync is detected in the event of a momentary interruption or interruption of the communication line at the time of handover, noise is suppressed, and when the transmission status is restored, the link for multiplex transmission is quickly restored, and further transmission It is an object of the present invention to provide a means for suppressing deterioration of voice quality, especially generation of significant noise even when errors are continuous.

[0011]

Claim 1 SUMMARY OF THE INVENTION are such as voice
Information frames including real-time information and computer data
A certain number of information frames containing non-real-time information
The signals that appear in a predetermined order
To receive real-time and non-real-time information
In the wireless voice multiplex communication terminal device,
For each slot in which an information frame
Prepare independent error counters for each slot
Measuring means for measuring the number of consecutive errors and each error counter
A comparing means for comparing the number of consecutive errors with a threshold value;
The number of consecutive errors in one error counter is less than the threshold value.
In the above case, the circuit of the circuit that reproduces the received audio signal
And an audio mute means for performing the above-mentioned operation.

According to the first aspect of the present invention, when information frame errors continuously occur due to, for example, a momentary disconnection of a wireless line or a handover, an error of any slot
Continuous error count information frame detected by the counter is more than the threshold value, implementing a muting circuit for reproducing an audio signal is an audio mute unit received. Therefore, the generation of significant noise is suppressed .

[0013] For the error detection regarding received information frame, for example, CRC (Cyclic Redundancy Check)
It can be monitored by checking the code. If the first information frame including real-time information such as voice does not include the CRC code, the error in the first information frame cannot be directly detected.

However, since the first information frame containing real-time information and the second information frame containing non-real-time information such as computer data appear periodically in a predetermined order, they are detected for the second information frame. The error that has occurred in the first information frame can be estimated based on the error that has occurred. Claim 2 provides real-time information such as voice.
Non-real time including information frame and computer data
An information frame containing information is predetermined by a predetermined number
Real-time information by periodically receiving signals that appear in sequence
And wireless voice multiplexing terminal for receiving non-real time information
In the end device, the information frame targeted for retransmission control is
Independent error for each slot to be received
Prepare a counter to measure the number of consecutive errors for each slot.
Measuring means and the number of consecutive errors of each error counter
A comparison means to compare with the value and any one error count
If the number of consecutive errors in
A resynchronization means for performing resynchronization processing is provided.

In claim 2, either slot
Error of information frames detected by the error counter of
If the number is greater than or equal to the threshold, the resynchronization means performs the predetermined resynchronization processing
If you get out of sync, sync automatically.
Can be recovered.

The third aspect is real-time information such as voice.
Non-real time such as information frame and computer data including
A predetermined number of information frames containing
The signals that appear in different order are periodically received and real-time information is received.
Wireless voice communication for receiving information and non-real time information
Information frame to be subject to retransmission control in the terminal device
For each slot that should be received
-Preparing a counter to measure the number of consecutive errors for each slot
Measuring means and the number of consecutive errors of each error counter
First comparing means for comparing with the first threshold and each error counter
The number of consecutive errors of the data is greater than the first threshold value.
A second comparing means for comparing with a threshold value of 2;
The number of consecutive errors in the error counter is less than or equal to the first threshold value.
In the above case, the circuit of the circuit that reproduces the received audio signal
Audio muting means for implementing the
-The number of consecutive errors in the counter is greater than or equal to the second threshold value.
In this case, a resynchronization means for performing a predetermined resynchronization process is provided.

According to the third aspect, as in the first aspect, the sound mute means suppresses the generation of significant noise. Further, as in the second aspect, when the synchronization is lost, the synchronization can be automatically restored by the function of the resynchronization means .

A fourth aspect of the present invention is the radio of the first or third aspect.
In the audio multiplex communication terminal device,
Mute count that counts the number of times the path was muted
Measuring means and the number of times the muting is performed within a predetermined time
If the number is more than the specified number, disconnect the established communication line
And a line disconnecting means for controlling the line.

According to a fourth aspect of the present invention, the mi
Will be established when the number of
The disconnecting means disconnects the established wireless communication line. Therefore,
Useless communication times when the deterioration of communication quality is not resolved for a long time.
You can avoid using lines.

[0020]

[0021]

Claim 5 is Claim 1, Claim 2, Claim
3. The wireless voice multiplex communication terminal device according to claim 3 or 4.
Information that causes logical inconsistency in retransmission control
When the reception of frames is detected continuously for a certain threshold or more.
In this case, a contradiction detecting means for performing resynchronization processing is further provided.

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

In the communication terminal on the receiving side, for example, at the time of a momentary interruption or a communication interruption in a wireless section, the same data that was normally received last may be repeatedly input by retransmission. In such a case, no abnormality is detected in the CRC code inspection of the information frame received at the reception timing of the frame to be retransmitted. That is, the transmission error cannot be detected only by monitoring the CRC error, and the computer data or the like is passed to the audio decoder.

In this way, when the data that is inconsistent with respect to the retransmission control logic is continuously received, the inconsistency detecting means of claim 5 detects an error, and the media between the transmitting side and the receiving side communication terminals is detected. Reestablish the link for multiplex transmission. A contradiction occurs from the viewpoint of the retransmission control logic, for example, when information frames having the same frame number are continuously received, even though the reception has already been confirmed, the time exceeds N times the round trip delay. This is the case, for example, when a retransmission request for the same frame is received, or although the terminal itself is transmitting new data, it continuously receives delivery confirmation for the same information frame.

[0031]

DETAILED DESCRIPTION OF THE INVENTION (First Embodiment) One embodiment of a wireless audio multiplex communication terminal equipment of the present invention shown in FIGS. 1 and 3-6. This form is for all claims
Corresponds to the term .

FIG. 1 is a flow chart showing the main part of control in the first embodiment. FIG. 3 is a time chart showing a configuration example of a frame and a slot of a signal to be transmitted. FIG. 4 is a block diagram showing a configuration example of a communication system. FIG. 5 is a protocol stack diagram showing a protocol configuration on the mobile terminal device. FIG. 6 is a flowchart showing a process for detecting a contradiction in a data link control protocol.

In this embodiment, the measuring means according to claim 1 is compared.
The means and the audio muting means respectively perform step S12,
It corresponds to S13 and S15. Moreover, the measuring hand of claim 2
The step, the comparison means, and the resynchronization means are respectively step S1.
2, corresponding to S19 and S21 .

The measuring means of claim 3 and the first comparison means
Stage, second comparing means, audio muting means and resynchronizing means
Are steps S12, S13, S19 and S15, respectively.
And S21 .

Further, the mute frequency measuring means and the mute frequency measuring means of claim 4 are provided.
And the line disconnecting means correspond to steps S16 and S18 , respectively.

The contradiction detecting means of claim 5 is the step S5.
It corresponds to 1, S52 and S53. In this mode, as shown in FIG. 4, the mobile terminal device 100 and the center terminal device 20 are connected.
0 is used to configure the communication system. Of course, it is also possible to use a plurality of mobile terminal devices 100 having the same configuration and perform communication between the plurality of mobile terminal devices 100.

The mobile terminal device 100 shown in FIG. 4 includes a portable personal computer 110, a camera 120 with a capture function, a communication interface unit 130, and a PH.
S terminal 140, PC card interface 150 and 1
It is composed of 60. The portable personal computer 110 is a commercially available standard-sized small computer. The camera with capture function 120 is C
This is a camera using a two-dimensional image pickup device such as a CD, which repeatedly takes an image at a predetermined timing and sequentially outputs the captured image data. Camera 120 with capture function
Is connected to the portable personal computer 110 using a commercially available PC card interface 150.

On the other hand, the communication interface unit 130
Includes a call circuit 131, a voice codec 132, a memory 133, a CPU 134 and a 32 kbps line interface 1.
35 is equipped. Communication interface unit 13
The internal bus of 0 is a commercially available PC card interface 16
It is connected to the portable personal computer 110 via 0. A PHS terminal 140 is connected to the 32kbps line interface 135.

Therefore, the mobile terminal device 100 can transmit and receive radio signals via the PHS terminal 140. Since the PHS terminal 140 is used in this example, the data transmission rate is 32 kbps. The PHS base station 310 that wirelessly communicates with the PHS terminal 140 is connected to the ISDN network 320 by wire. And this ISDN network 320
The center terminal device 200 is connected to.

Computer 21 of the center terminal device 200
0, a communication interface unit 220 is connected via a PCI bus interface 230. The communication interface unit 220 includes a CPU 221, a memory 222, a voice codec 223, a communication circuit 224, and a communication circuit 224.
32kbps line interface 225, speed conversion circuit 226
And an ISDN interface 227.

The CPU 221, the memory 222, the audio codec 223, the communication circuit 224, the 32 kbps line interface 225 and the PCI bus interface 230 are connected to each other via the internal bus of the communication interface unit 220. 32kbps line interface 225
Is connected to the ISDN interface 227 via the speed conversion circuit 226.

The speed conversion circuit 226 converts the data transmission speed in order to match the data transmission speeds of the 32 kbps line interface 225 and the ISDN interface 227. The ISDN interface 227 is an IS
It is connected to the DN network 320.

In the mobile terminal device 100, the digital image obtained by the image capturing by the camera 120 with the capture function and the voice input from the communication circuit 131 are PHS.
It can be transmitted in the form of a wireless signal via the terminal 140. In reality, both the digital image and the voice are encoded and transmitted as a signal in which the digital image and the voice are multiplexed.

When the PHS terminal 140 receives a signal in which the digital image and the voice are multiplexed, the digital image and the voice are separated and decoded respectively, and the voice is output from the call circuit 131 to be portable. An image is displayed on a display unit built in the personal computer 110. The center terminal device 200 has almost the same functions as the mobile terminal device 100. However, in reality, the center terminal device 200
Is configured to be able to communicate with four mobile terminal devices 100 at the same time.

The control system protocol in the mobile terminal device 100 is configured as shown in FIG. As shown in FIG. 5, the control system on the portable personal computer 110 includes a transmission frame generation 510 and an image encoding / decoding 52.
0, communication control 530, image capture ring 540, and image display 550. These protocols are realized by executing software of the portable personal computer 110.

On the other hand, the communication interface unit 130
The control system protocol in is a 32 kbps digital bearer 410, media multiplexing 420, voice encoding / decoding 4
30 and ARQ (Automatic Request fo of transmission frame)
r Repetition) control 440. Communication interface unit 130
The above protocol is implemented by software that is processed by dedicated hardware and executed by the built-in CPU 134. For example, the voice encoding / decoding 430 protocol is realized by the hardware of the voice codec 132.

In PHS communication, it is possible to transmit data by utilizing the empty areas of the time slots formed in time series by time division multiplexing. Also, P
In HS communication, one information frame (T-CH frame) and three communication channels are multiplexed,
The mobile terminal device 100 and the center terminal device 200 use only the T-CH frame allocated for information transmission.

That is, in this example, real-time information such as voice and non-real-time information such as computer data and image data are time-division multiplexed in units of 160-bit T-CH frames transmitted and received by the PHS 32 kbps digital bearer terminal in units of 5 msec. And then transmit. The signal actually transmitted between the mobile terminal device 100 and the center terminal device 200 is configured as shown in FIG. 3, for example. In the example of FIG. 3, the information frames F1, F2, F2, F2, F1, F2, F are set at the timing of each frame that appears in the time period t.
2, ... is assigned.

In this example, real-time information such as voice is assigned to the information frame F1 of the first group, and this information frame F1 is not subject to retransmission control. Further, the CRC code is not attached to the information frame F1 and the frame error check is omitted. Non-real time information such as computer data and image data is assigned to the information frame F2 of the second group, and retransmission control is performed for this information frame F2. That is,
The presence or absence of a transmission error is identified by checking the CRC code added to the information frame F2, and when an error is detected, retransmission control of that information frame is performed.

Further, in the example of FIG. 3, the information frame F1 of the first group for voice transmission and the information frame F2 of the second group used for the transmission of the image data are set to have the same frame length, and for the voice. It shows a case where image data or the like is transmitted in a triple band. Each information frame F1, F2
Is not added with a flag or the like for distinguishing the groups. In this example, for example, Japanese Patent Laid-Open No. 9-219
The information frames F1 and F2 are distinguished by using frame timing synchronization as disclosed in Japanese Patent No. 684.

That is, between the mobile terminal device 100 and the center terminal device 200 which communicate with each other, a pattern of the order of transmitting the information frames F1 and F2 is set,
The information frames F1 and F2 are transmitted and received according to the order. For example, in the example of FIG. 3, the information frames F1 of the first group are arranged in the first frame, three information frames F2 of the second group appear subsequently, and the appearance pattern of such an order is four frame periods. repeat. Therefore, by grasping the position (timing) of the first frame of the received signal on the receiving side, it is possible to distinguish each information frame group without referring to the contents of each frame.

However, if a handover for switching the PHS base station 310 to be used or a momentary disconnection of the wireless line occurs due to the movement of the mobile terminal device 100, an error continuously occurs in the information frame to be transmitted, and the frame is transmitted. Sometimes timing is out of sync. Further, since the information frame does not include a flag for identifying the group, the information frame including image data or the like may be erroneously input to the audio circuit. Therefore, significant noise may occur.

Therefore, in this example, the mobile terminal device 100
In the circuit on the receiving side of the center terminal device 200, the control shown in FIG. 1 is executed for the error of the generated information frame. Further, in order to detect the number of error frames that appear continuously, as shown in FIG. 3, error counters EC1, EC2, EC3 associated with each time slot are provided.
Is provided. However, for the information frame of the first group, since it does not include the CRC code, the occurrence of an error cannot be directly detected.

However, if errors occur continuously,
There is a high probability that an error will occur not only in the information frame of the first group but also in the information frame of the second group adjacent thereto. Therefore, the error in the information frame of the first group can be estimated from the error occurring in the information frame of the second group. Since the CRC code is included in the information frame of the second group for retransmission control, the error of the information frame of the second group can be directly detected.

The error counters EC1, EC2, EC3 are prepared for all the slots in which the information frame including the CRC code appears when the signal timings of the transmitting side and the receiving side are matched. In FIG. 3, the error counters EC1, EC2, and EC3 respectively indicate the reception timing (T
1+ (1 + 4m) t), (T1 + (2 + 4m) t),
Continuous errors are counted by (T1 + (3 + 4m) t) (m = 0, 1, 2 ...).

Here, 3 of the frames subject to retransmission control
The number of consecutive errors is counted for each reception timing.
This is to enable out-of-synchronization detection when the frame timing perceived by the transmitting side deviates from the frame timing perceived by the receiving side due to a momentary interruption or the like in the wireless transmission path. In other words, if a missing or erroneous bit is inserted in the bit sequence transmitted in the order of transmission on the transmission side, the location where the CRC, which the reception side is aware of, should be originally written in the transmission frame subject to retransmission control. The data of the dislocated place is C
Since it is processed as RC, a CRC error occurs in each transmission frame. However, when information is lost in transmission frame units due to a momentary interruption or the like, the reception timing (T1 + (1 + 4m) t) of the frame in which the retransmission control target is the information frame F1 of the first group that is not the retransmission control target, ( T1
+ (2 + 4m) t) and (T1 + (3 + 4m) t) will be received. Also, (T1 + (1 + 4m) t),
(T1 + (2 + 4m) t), (T1 + (3 + 4m) t)
Since it is uncertain at which timing the data will be received, an independent error counter is assigned to each timing and continuous errors are monitored at each timing.

There is a high possibility of continuously detecting an error in the received information frame in the following cases. (1) When continuous frame errors occur due to temporary deterioration of transmission conditions. (2) When the transmission quality is constantly poor around the service area of the wireless base station. (3) In the case where the handover operation occurs as a result of the mobile terminal device 100 moving beyond the service area edge of the radio base station.

When the control shown in FIG. 1 is carried out, under the above condition (1), it is determined whether or not the voice codec is muted according to the length of time during which the deterioration of the transmission condition continues. When the duration is short, noise is generated during that time. However, in a vocoder (voice communication device) as shown in the ITU standard number (G.729), since a code considering a code error is used, fatal noise does not occur. If the duration is long, the audio codec is muted.

In the case of the above (2), there is a possibility that a state in which the communication state is recovered after the frame errors continue and then the frame errors continue again occurs repeatedly. Under such conditions, when the control of FIG. 1 is performed, the mute operation of the voice codec repeatedly works. It is desirable to forcibly disconnect the connection if the minimum condition for establishing communication cannot be met. Therefore, the number of times the mute operation is activated in a certain period of time is counted, and if the number of mute operations exceeds a predetermined threshold within the certain period during voice multiplex transmission, the line is disconnected.

In the case of the above (3), transmission errors continue near the edge of the service area, but the transmission state is restored when the mobile station is handed over and moves to another area. Even if it is about the time for activating the mute operation of the voice codec or about the time for activating the resynchronization, the communication state is restored to normal after the temporary interruption of the communication.

The contents of the control shown in FIG. 1 will be described.
As a result of checking the CRC code added to each information frame, if a transmission error of the information frame is detected, the process proceeds from step S11 to S12. Step S12
Then, the error counter of the corresponding time slot is counted up. For example, the time (T1 + 2
When a transmission error is detected in the information frame appearing between t) and (T1 + 3t), 1 is added to the count value of the error counter EC2. When no transmission error is detected, the count value of the error counter is cleared to 0. Therefore, the error counter counts the number of consecutive frames related to the transmission error of the information frame.

In step S13, the count values of the error counters EC1, EC2, EC3 of each slot are compared with a predetermined threshold value M. Error counters EC1, EC2, E
If any one of the count values of C3 is greater than or equal to the threshold value M,
In step S15, the audio codec 132 (or 2
The sound reproduction output of 23) is muted (or the output level is reduced).

If all the count values of the error counters EC1, EC2, EC3 are less than the threshold value M, step S14
Then, the normal operation, that is, the multiplex transmission of the audio signal and the image data is continued. After muffling, in step S16, the muffling number Cm within the fixed time Tm is calculated. For example, when the silencing operation and its cancellation frequently occur, the silencing frequency Cm within the fixed time Tm increases.

In step S17, the number of mute times Cm within the fixed time Tm is compared with the threshold value L. The number of muffling times Cm is the threshold value L
If it is larger, the process proceeds to step S18, and the communication line secured at that time is disconnected. That is, it is determined that the state of (2) has fallen.

If the mute count Cm is less than or equal to the threshold L, the number of consecutive error frames is continuously monitored. Then, when the count value of any one of the error counters EC1, EC2, EC3 is equal to or greater than the threshold value N, it is determined that the situation is the above (3), and the resynchronization process is executed in step S21. Also,
If the number of consecutive error frames is greater than or equal to M and less than N, it is determined that the transmission errors are consecutive due to a temporary deterioration of the transmission state,
In step S20, the mute operation of the audio codec 132 is canceled, and in step S14, the media multiplex transmission mode is restored. In addition, in FIG. 1, (M <N), and the actual value of the threshold value N may be, for example, about four times the threshold value M. The threshold L may be set to about 10 and the fixed time Tm may be set to about 10 seconds.

By the way, when a momentary interruption or communication interruption occurs in the wireless section, the last data normally received by the PHS terminal 140 and transferred to the communication interface unit 130, that is, already stored in the buffer on the communication interface unit 130 side. The same accumulated data may be repeatedly transmitted from the PHS terminal 140 to the communication interface unit 130.

In such a case, the CRC check of the information frame received at the reception timing of the information frame F2 of the second group to be retransmitted and the CRC written in the frame match, so the CRC check is correct. To be judged. Therefore, there are cases where a transmission error cannot be detected only by monitoring the CRC error, and computer data etc. may be passed to the audio decoder.

Therefore, when data that is inconsistent with respect to the retransmission control logic is continuously received, the same process as the CRC error is performed. Inconsistent data as seen from the retransmission control logic here means that when information frames with the same frame number are received consecutively even though the reception has already been confirmed, the time that is equal to or more than a predetermined multiple of the round trip delay. For example, when a retransmission request for the same frame is received over a period of time, or when the terminal itself is continuously transmitting new data, the delivery confirmation for the same information frame is continuously received.

That is, in the contradiction detection process shown in FIG. 6, it is determined in step S51 whether or not the reception-confirmed frames have been continuously received Q1 times, and in step S52, the retransmission request time for the same frame is round trip delay. It is determined whether or not the product is larger than the product of Rtt and Q2, and in step S53, the delivery confirmation of the same frame is confirmed by Q3.
It is identified whether or not it has been received consecutively. If any of the conditions in steps S51, S52, and S53 is satisfied, the process proceeds to step S54, and the resynchronization process is executed.

As described above, the mobile terminal device 100 and the center terminal device 200 of this embodiment do not transmit voice data that does not guarantee error free, but transmit computer data and image data that guarantee error free by retransmission control. Monitor the occurrence of errors by CRC inspection etc.,
The transmission state relating to the voice data is estimated according to the transmission error occurrence state, and when a constant level transmission error occurs continuously, the reproduction circuit of the voice codec 132 (223) is muted and the error is monitored. If the continuation of transmission errors is resolved after a certain period of time after the mute operation on the receiving side is started, the mute control is canceled to restart the voice reproduction, and after the mute control, a certain time (Tm) If the continuous error is not resolved even after the lapse of time, it is estimated to be a handover or movement to the outside of the service area, and once the link is resolved, the link is re-established, thereby suppressing the occurrence of significant noise.

(Second Embodiment) This embodiment is a modification of the first embodiment and is the same as the first embodiment except that the control contents shown in FIG. 1 are replaced with the control contents shown in FIG. It is the same .

(Vacancy)

(Vacancy)

Referring to FIG. 2, the content of the process is simplified as compared with FIG. In step S32, the continuous error of the frame is compared with the threshold value M. Then, if the continuous error of the frames is equal to or more than the threshold value M, the audio codec is muted in step S34. Further, step S3
At 5, the frame continuation error is compared with a threshold N. If the frame continuation error is less than the threshold value N, mute cancellation is executed in step S36.

[0075]

As described above, the present invention employs a highly efficient media multiplex transmission system capable of establishing synchronization on a wireless transmission line by using timing synchronization without using a synchronization flag after pulling in synchronization. ing. Further, it is possible to suppress the occurrence of noise by detecting the out-of-synchronization when the communication line is interrupted due to a momentary interruption or a handover that occurs in a wireless section when performing media multiplex transmission. Furthermore, when the transmission state is restored, the link for multiplex transmission can be quickly restored. Further, there is an effect that the means for suppressing the deterioration of the voice quality, especially the generation of remarkable noise, can be realized by a simple means even if the transmission errors are continuous.

[Brief description of drawings]

FIG. 1 is a flowchart showing a main part of control according to a first embodiment.

FIG. 2 is a flowchart showing a main part of control according to a second embodiment.

FIG. 3 is a time chart showing a configuration example of a frame and a slot of a signal to be transmitted.

FIG. 4 is a block diagram showing a configuration example of a communication system.

FIG. 5 is a protocol stack diagram showing a protocol configuration on a mobile terminal device.

FIG. 6 is a flowchart showing a contradiction detection process of a data link control protocol.

[Explanation of symbols] 100 mobile terminal devices 110 Portable personal computer 120 Camera with capture function 130 Communication interface unit 131 call circuit 132 audio codecs 133 memory 134 CPU 135 32kbps line interface 140 PHS terminal 150,160 PC card interface 200 Center terminal device 210 computers 220 Communication interface unit 221 CPU 222 memory 223 audio codec 224 communication circuit 225 32kbps line interface 226 speed conversion circuit 227 ISDN interface 230 PCI bus interface 310 PHS base station 320 ISDN network 410 32kbps digital bearer 420 media multiplexing 430 Speech coding / decoding 440 ARQ control of transmission frame 510 Transmission frame generation 520 Image encoding / decoding 530 communication control 540 image capturing 550 image display

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-9-219684 (JP, A) JP-A 8-65276 (JP, A) JP-A 63-194439 (JP, A) JP-A 4- 14921 (JP, A) JP-A-8-163071 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01J 3/00 G10L 11/02 G10L 19/00

Claims (5)

(57) [Claims] 1. Information including real-time information such as voice information
Includes non-real-time information such as frames and computer data
Information frames and a predetermined number of information frames in a predetermined order.
The received signal is received periodically to provide real-time information and
For wireless voice multiplex communication terminal device that receives real-time information
In this case, the information frame subject to retransmission control should be received.
An independent error counter is prepared for each lot.
And a measuring means for measuring the number of consecutive errors for each slot, and a ratio for comparing the number of consecutive errors of each error counter with a threshold value.
The comparison means and the number of consecutive errors in any one error counter are
Mute the circuit that reproduces the received audio signal when the threshold is exceeded.
A wireless voice multiplex communication terminal device comprising: an audio mute unit . 2. Information including real-time information such as voice
Includes non-real-time information such as frames and computer data
Information frames and a predetermined number of information frames in a predetermined order.
The received signal is received periodically to provide real-time information and
For wireless voice multiplex communication terminal device that receives real-time information
In this case, the information frame subject to retransmission control should be received.
An independent error counter is prepared for each lot.
And a measuring means for measuring the number of consecutive errors for each slot, and a ratio for comparing the number of consecutive errors of each error counter with a threshold value.
The comparison means and the number of consecutive errors in any one error counter are
A re-synchronization means for performing a predetermined re-synchronization process when the threshold value or more is satisfied . 3. Information including real-time information such as voice
Includes non-real-time information such as frames and computer data
Information frames and a predetermined number of information frames in a predetermined order.
The received signal is received periodically to provide real-time information and
For wireless voice multiplex communication terminal device that receives real-time information
In this case, the information frame subject to retransmission control should be received.
An independent error counter is prepared for each lot.
Te, a measuring means to measure the continuous number of errors for each slot, the number of continuous errors for each error counter and the first threshold comparator
And the first threshold value for the continuous error number of each error counter.
The second comparing means for comparing with the second threshold which is larger than the second threshold, and the number of consecutive errors in any one of the error counters
Note: Plays the received audio signal when it is above the first threshold.
Audio muting means for muting the circuit to be connected and the number of consecutive errors in any one error counter
Note that if the second threshold value is exceeded, a predetermined re-synchronization process is performed.
Wireless voice multiplex communication characterized by having a synchronization means
Terminal device . 4. The wireless voice multiplex communication according to claim 1 or 3.
The number of times the circuit that reproduces the audio signal is muted
Mute number counting means for counting, and the number of times the mute is performed within a predetermined time is less than a predetermined number.
If it is above, a disconnecting hand that disconnects the established communication line
A wireless voice multiplex communication terminal device , further comprising a step . 5. Claim 1, claim 2, claim 3 and claim
In the wireless voice multiplex communication terminal device according to any one of the items 4 to 4, of the information frame which causes logical inconsistency in retransmission control.
Resync when reception is detected continuously for a certain threshold or more
A wireless voice multiplex communication terminal device , further comprising a contradiction detection means for performing processing .