JP3313564B2 - Multiplexer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplexing apparatus in a mobile communication terminal having a variable rate codec, and more particularly to forcibly reducing a maximum voice data rate while ensuring that control data is transmitted within a time limit. The present invention relates to a multiplexing device for a mobile communication terminal which minimizes the deterioration of voice quality due to the communication.

[0002]

2. Description of the Related Art In recent years, particularly in the field of mobile communications, a communication system that performs voice coding using a variable rate codec has been receiving attention. In such a system, a means for sharing and multiplexing control data such as call control information and coded voice data in the communication capacity of one channel and transmitting the multiplexed data may be employed. At this time, since the information rate of the audio data is variable, if the control data is inserted into the gap of the communication capacity occupied by the audio data, the audio quality does not deteriorate.

[0003] However, in many cases, the transmission of control data must be completed within a certain time limit. Therefore, it is necessary to reduce the maximum audio data rate allowed for the variable rate codec to some extent to secure the communication capacity of control data. Occurs. Therefore, there is a need for a multiplexing technique capable of minimizing the deterioration of voice quality while guaranteeing the control data transmission time limit.

FIG. 9 shows a schematic configuration of a mobile communication terminal using a multiplexing device according to the prior art. In FIG. 9, the mobile communication terminal includes an antenna 1, a transmitting unit 2, a multiplexing unit 3, a variable rate codec 4, a microphone 5, a control data unit 6, a receiving unit 7, a separating unit 8, an audio decoder 9, and a speaker 10.
And an audio rate control unit 100.

Next, the operation of the multiplexing device in the conventional mobile communication terminal will be described. The transmission signal and the reception signal in the antenna 1 are synchronized with the base station and are configured by frames divided in a certain time unit.

[0006] The reception signal from the antenna 1 is demodulated by the reception unit 7 and sent to the separation unit 8. The separating unit 8 separates the audio data and the control data multiplexed in the demodulated signal into frames, and sends the audio data to the audio decoder 9 and the control data to the control data unit 6. The audio data sent to the audio decoder 9 is decoded and sent out from the speaker 10 as audio.

The control data section 6 analyzes the control data sent from the separation section 8, generates control data to be transmitted, and sends it to the multiplexing section 3. The audio rate control unit 100 detects that the control data unit 6 has generated control data, and instructs the variable rate codec 4 to reduce its maximum audio data rate. The variable rate codec 4 determines the rate of the sound input from the microphone 5 on a frame basis based on the sound pressure, generates sound data, and sends the sound data to the multiplexing unit 3.

The variable rate codec 4 sets the maximum audio data rate allowed for normal audio data equal to the maximum data rate of the normal channel, but reduces the maximum audio data rate when instructed. The multiplexing unit 3 accumulates the control data sent from the control data unit 6 and multiplexes the audio data and the control data in frame units and sends the multiplexed data to the transmitting unit 2. At this time, the audio data is first inserted into the frame, and if there is stored control data, the control data or a part thereof is inserted into the vacant communication capacity of the frame.

The transmitting section 2 modulates the data multiplexed by the multiplexing section 3 and transmits the modulated data from the antenna 1. Audio rate control unit
When the control unit 100 detects that the control data stored in the multiplexing unit 3 has been transmitted, it instructs the variable rate codec 4 to return the maximum audio data rate to normal. The variable rate codec 4 receives the instruction and resets the maximum audio data rate allowed for the audio data to be equal to the maximum data rate of the communication channel.

Next, the multiplexing method according to the prior art will be described in detail. Here, one frame has a communication capacity of a maximum of 24 bytes, and the maximum audio data rate is 24 bytes per frame at normal time and 12 bytes per frame at control data transmission. The variable rate codec 4 generates any one of 24 bytes, 12 bytes, 6 bytes, and 3 bytes of audio data per frame.

At some point in time, the control data section
When byte control data is generated, the audio rate control unit
100 indicates to the variable rate codec 4 12 bytes per frame as the maximum audio data rate. Thereafter, the variable rate codec 4 generates one of 12 bytes, 6 bytes, and 3 bytes of audio data per frame until the next instruction. Therefore, at least a 12-byte capacity is secured for the control data in each frame.

FIG. 10 shows an example of the amount of audio data for each frame generated by the variable rate codec 4 and how control data is multiplexed in each frame.

In FIG. 10, reference numeral 101 denotes an audio data amount for each frame, 102 denotes a control data amount for each frame, and 103 denotes a frame in which the audio rate control unit 100 instructs the variable rate codec 4 to reduce the maximum audio data rate. 1
Frame number, 104 is the amount of data (bytes)
Is the vertical axis of the graph showing the graph.

In this example, since the control data transmission capacity of 84 bytes was secured between the frame numbers 1 to 6, the voice rate control unit 100 Instructs the audio data rate to return to 24 bytes per frame.

[0015]

The data rate of audio data encoded by the variable rate codec is high in a voiced state and low in a silent state. Therefore, although the audio data rate has a stochastic fluctuation, a control data rate that can be secured even when the audio data rate is not forcibly operated can be expected when a long time is assumed to some extent.

If the required control data rate obtained by the control data amount and its transmission time limit is not much higher than the expected control data rate, the control data rate can be reduced without forcibly reducing the maximum audio data rate. May be sent in time.

Nevertheless, in the above conventional example,
The maximum audio data rate was unconditionally reduced, resulting in deterioration of audio quality during that period.

For example, in the graph of FIG. 10 showing the relationship between the amount of audio data per frame and the amount of control data per frame, the control data of 84 bytes is transmitted by the frame whose frame number is 12. It is assumed that transmission can be performed. Between 1 and 12 frames
For example, a state where the audio data rate is the lowest such as frame numbers 7 to 10 may exist.

Therefore, if control data is multiplexed after waiting for those frames, it is not necessary to reduce the maximum audio data rate in frame numbers 1 to 6.

The present invention solves such a conventional problem, and degrades voice quality by forcibly reducing the maximum voice data rate while ensuring that control data is transmitted within a time limit. The goal is to minimize.

[0021]

In order to achieve the above object, according to the first aspect of the present invention, when control data is to be multiplexed and transmitted by a frame at a certain time limit, the control data is generated when the control data is generated. Means for presetting and storing the minimum cumulative control data transmission amount from the time to the time limit as a minimum cumulative control data transmission amount curve which is a function of time;
Means for storing the total amount of control data actually transmitted from the time of generation of the control data, and the difference between the cumulative control data transmission amount and the value of the minimum cumulative control data transmission amount curve in each frame from the time of the control data generation to the time limit Means for forcibly reducing the maximum audio data rate.

According to a second aspect of the present invention, when control data is generated, one or more integer constants are set and stored as a window width, and each frame has a number equal to the window width including the frame. In order to keep the average control data rate of past frames always above a certain level,
Means for instructing the variable rate codec to forcibly reduce the maximum audio data rate of the frame as needed.

According to a third aspect of the present invention, the window width
The storage unit and the control actually transmitted since the control data was generated
Cumulative control data transmission amount storage unit that stores the total amount of data
In addition , instead of the window control unit, in each frame, while calculating the remaining control data amount from the cumulative control data transmission amount notified from the cumulative control data transmission amount storage unit, and including the frame The maximum number of frames in the past so that the control data rate of the number of past frames equal to the window width is equal to or greater than the required control data rate obtained from the amount of remaining control data and the remaining time up to the transmission time limit of the control data. Means are provided for instructing the variable rate codec to forcibly reduce the audio data rate.

According to a fourth aspect of the present invention, the control data amount required in the window in each frame is one.
Means are provided for updating the window width for each frame so as to be equal to or less than the maximum value of the control data amount that can be obtained by operating the frame so that the audio data rate is minimized.

According to a fifth aspect of the present invention, there is provided means for setting and storing a preset average audio data rate,
In each frame, the control data rate obtained from the average audio data rate read from the audio rate rate storage unit
Comprising means for determining the difference between the expected value and the required control data rates over preparative, and means for instructing a variable rate codec to forcibly reduce the maximum audio data rate of the frame in accordance with the value of the difference I have.

The invention according to claim 6 is provided with means for obtaining a statistic of the audio data rate encoded by the variable rate codec in each frame and updating the average audio data rate.

With such a configuration, the multiplexing device according to the first aspect of the present invention uses the accumulation of the accumulated control data transmission amount that increases more rapidly in a state closer to silence, and reduces the control data rate in the frame in the sound state. By covering the reduction of the allocation, the number of times of forced reduction of the maximum audio data rate can be reduced.

The multiplexing apparatus according to the second aspect absorbs the stochastic fluctuation of the voice data rate due to voiced and non-voiced sound by the window width and forcibly reduces the maximum voice data rate to prevent the deterioration of voice quality. It has the effect that it can be minimized.

According to the third aspect of the present invention, the multiplexing device stores the accumulated control data transmission amount and determines the required control data rate from the remaining control data amount. Is high enough,
This has the effect of reducing the rate at which the maximum audio data rate thereafter is forcibly reduced, thereby reducing audio quality degradation.

The multiplexing device according to the fourth aspect has the effect of preventing the deterioration of voice quality due to the continuous minimum of the voice rate.

In the multiplexing apparatus according to the present invention, when the probability that the audio data rate is not required to be operated is higher than the probability that the audio data rate must be operated, the audio data rate is not forcibly reduced. This has the effect of reducing the possibility of unnecessary voice quality degradation.

The multiplexing device according to the sixth aspect has the effect of further reducing the possibility of unnecessary voice quality deterioration by using a more plausible value of the voice data rate.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 shows a schematic configuration of a mobile communication terminal using a multiplexing device according to a first embodiment of the present invention.

In FIG. 1, the mobile communication terminal includes an antenna 1, a transmitting unit 2, a multiplexing unit 3, a variable rate codec 4, a microphone 5, a control data unit 6, a receiving unit 7, a separating unit 8, an audio decoder 9, and a speaker 10. , Cumulative control data transmission amount storage unit 1
1. It comprises a lowest cumulative control data transmission section curve storage section 12 and a cumulative data amount comparison section 13.

Next, the operation of the multiplexer in the mobile communication terminal will be described. The transmission signal and the reception signal in the antenna 1 are synchronized with the base station and are configured by frames divided in a certain time unit.

The signal received from antenna 1 is demodulated by receiving section 7 and sent to separating section 8. The separating unit 8 separates the audio data and the control data multiplexed in the demodulated signal into frames, and sends the audio data to the audio decoder 9 and the control data to the control data unit 6. The audio data sent to the audio decoder 9 is decoded and sent out from the speaker 10 as audio.

The control data section 6 analyzes the control data sent from the separating section 8, generates control data to be transmitted, and sends it to the multiplexing section 3. At this time, the transmission restriction time T of the control data is designated. Cumulative control data transmission amount storage unit
Reference numeral 11 updates and stores the accumulated transmission data amount of the control data multiplexed and transmitted by the multiplexing unit 3 for each frame.

When the control data is generated, the minimum accumulated control data transmission amount curve storage unit 12 reads the data amount D, the generation time t ₀ and the transmission restriction time T from the control data unit 6, and at time t ₀ , 0, A straight line that is D at time T is defined and stored as a minimum accumulated control data transmission amount curve S _min (t) that is a function of time t. Since it is assumed that the transmission of the control data can be completed by time T, the slope of S _min (t) should be smaller than the control data rate that can be secured by reducing the audio data rate to the maximum.

By the way, the accumulated data amount comparing unit 13 determines that the leading time of the frame is t _i and the time interval of the frame is t _f in all the frames between the times t ₀ and T.
The cumulative control data transmission amount D (t _i ) notified from the cumulative control data transmission amount storage unit and the minimum cumulative control data transmission amount S _{min at} t _i + t _f stored in the minimum cumulative control data transmission amount curve storage unit 12. Compare the value of (t _i + t _f ).

If D (t _i ) is equal to or greater than S _min (t _i + t _f ), D (t _i + t _f ) will remain even if the amount of data allocated to control data in that frame is zero. S
Since it does not fall below _min (t _i + t _f ), no operation is performed on the audio data rate.

If D (t _i ) is less than S _min (t _i + t _f ), the control data amount S _min (t _i + t _f ) -D
The maximum audio data rate at which (t _i ) can be secured is instructed to the variable rate codec 4. that time,
As described above, since the slope of S _min (t) should be smaller than the maximum control data rate, the control data amount S _min (t _i +
t _f) -D (maximum speech data rate as t _i) can be at least ensured always exists.

The variable rate codec 4 determines the rate of the sound input from the microphone 5 on a frame basis based on the sound pressure, generates sound data, and sends it to the multiplexing unit 3. The variable rate codec 4 sets the maximum audio data rate allowed for normal audio data equal to the maximum data rate of the communication channel, but reduces the maximum audio data rate when instructed.

The multiplexing unit 3 accumulates the control data sent from the control data unit 6, multiplexes the audio data and the control data in frame units, and sends the multiplexed data to the transmission unit 2. that time,
First, voice data is inserted into a frame, and if stored control data is present, the control data or a part thereof is inserted into a vacant portion of the communication capacity of the frame. The transmitting unit 2 modulates the data multiplexed by the multiplexing unit 3 and transmits the modulated data from the antenna 1.

Next, the relationship between the minimum cumulative control data transmission amount curve and the cumulative control data transmission amount used in the present embodiment will be described.

In FIG. 2, the minimum cumulative control data transmission amount curve 30 and the cumulative control data transmission amount 31 are represented as functions of time (ms). In FIG. 2, the generation time of the control data is set to 0 for convenience. Here, one frame is the maximum
It has a communication capacity of 24 bytes and a maximum audio data rate of 24 bytes per frame at normal times. The variable rate codec 4 generates any one of 24 bytes, 12 bytes, 6 bytes, and 3 bytes of audio data per frame. Further, the length of one frame is set to 20 ms.

At time 120 ms in FIG. 2, the accumulated control data transmission amount 31 is 48 bytes, and at time 140 ms at the beginning of the next frame, the minimum accumulated control data transmission amount curve 30 is 49 bytes. The accumulated data amount comparison unit 13 instructs the variable rate codec 4 to have a maximum audio data rate of 12 bytes per frame so that at least one byte of control data can be secured in a frame whose head time is 140 ms.

As described above, according to the above embodiment of the present invention, the maximum audio data rate is operated only when the cumulative control data transmission amount may intersect the minimum cumulative control data transmission amount curve. Voice quality degradation can be reduced while ensuring that control data transmission is completed within the time limit.

By setting a curve having a small slope at the beginning and a large slope at the end of the period as the minimum accumulated control data transmission amount curve, it is possible to prevent a sound state from being accidentally continued at the beginning.
Relatively large stochastic fluctuations in the stage where the elapsed time is short can be absorbed in a long time, and unnecessary operation of the audio data rate can be reduced.

(Second Embodiment) FIG. 3 shows a schematic configuration of a mobile communication terminal using a multiplexer according to a second embodiment of the present invention. This embodiment is different from the first embodiment already described with reference to FIG. 1 in that the cumulative control data transmission amount storage unit 11, the minimum cumulative control data transmission unit curve storage unit 12, the cumulative data amount comparison unit 13 Is provided with a window control unit 14 and a window width storage unit 15 in place of. The configuration of the other parts of the second embodiment is the same as that of the first embodiment already described, and the duplicate description will be omitted.

[0050] When to control data that has the data amount D generated at time t ₀ is multiplexed by the frame at time T, the window width memory 15 frame number N is smaller than that contained from time t ₀ to the T One window is set with W frames composed of one or more integer constants ( this is hereinafter referred to as a window width W) .

The window control unit 14 is a window width storage unit
It reads the window width W that is set at 15, in each frame in the time from time t ₀ to T, so that the control data in the past W frames containing the frame is secured over DW / N Operating the maximum audio data rate in the last frame of the window, or in a plurality of frames in a continuous window including the last frame.

For example, when the window width is 4 and the control data of 84 bytes is transmitted in 12 frames, the window control unit 14 operates to secure the control data of 28 bytes in the window, and ends the third frame of the window. When the control data has already been transmitted by d bytes, the maximum audio data rate is instructed to the variable rate codec 4 so that (28-d) bytes are secured in the fourth frame.

As described above, according to the above-described embodiment of the present invention, the maximum audio data rate is forcibly reduced by absorbing the stochastic fluctuation of the audio data rate due to the presence or absence of sound with the window width. The degradation of voice quality can be minimized, and the control data
Since / N or more is secured, it is possible to guarantee that the transmission of the control data of the data amount D within the N frames is completed.

(Third Embodiment) FIG. 4 shows a schematic configuration of a mobile communication terminal using a multiplexer according to a third embodiment of the present invention. This embodiment is different from the second embodiment already described with reference to FIG. 3 in that the accumulated control data transmission amount storage unit 11 described in the first embodiment is different from the second embodiment.
And a cumulative window control unit 16 is provided in place of the window control unit 14. The configuration of the other parts of the third embodiment is the same as that of the second embodiment already described, and the duplicate description will be omitted.

If certain control data having a data amount D is to be transmitted in N frames, the accumulation window control unit 16
Reads the window width W set in the window width storage unit 15 and, at the beginning of an arbitrary frame i of the N frames, stores the accumulated control data transmission amount storage unit
11 reads out the accumulated control data transmission amount D (i) stored therein, calculates the number of remaining frames N (i) including the frame, and furthermore, the control data is included in the past W frames including the frame ( DD (i)) The maximum audio data rate is manipulated in the last frame of the window or in a plurality of frames in a continuous window including the last frame so as to secure W / N (i) or more.

Next, this embodiment will be described in detail with reference to FIG. Here, it is assumed that the window width is 4, and 84 bytes of control data are transmitted in 12 frames.

Now, when the control data transmission amount up to the seventh frame is as shown in FIG. 5, in the eighth frame, the accumulative window control unit 16 calculates the remaining data amount 18 and the remaining number of frames 5 from 18 × 4/5 = 14.4 is obtained, and it is determined that the control data amount of the past four frames including the eighth frame is secured to 15 bytes. Since 12 bytes of control data have already been transmitted in the fifth to seventh frames, the cumulative window control unit 16 instructs the variable rate codec 4 to secure at least 3 bytes of control data in the eighth frame.

As described above, according to the above-described embodiment of the present invention, when frames in which the control data rate can be sufficiently secured continue to some extent due to the silence state, the required control data rate thereafter becomes low. The possibility of operating the maximum audio data rate can be reduced, and the deterioration of audio quality can be reduced.

(Fourth Embodiment) FIG. 6 shows a schematic configuration of a mobile communication terminal using a multiplexing device according to a fourth embodiment of the present invention. This embodiment is different from the third embodiment already described with reference to FIG. 4 in that a window width calculation unit 17 is newly provided instead of the window width storage unit 15. The other parts of the configuration of the fourth embodiment are the same as those of the third embodiment already described, and the duplicate description will be omitted.

When certain control data having a data amount D is to be transmitted in N frames, the window width calculation unit 17 sets the cumulative control data transmission amount storage unit 11 at the beginning of an arbitrary frame i of the N frames. Reads the accumulated control data transmission amount D (i) stored therein, and obtains N (i) d _max / (D) from the number of remaining frames N (i) including the frame.
-Set the largest integer not exceeding D (i)) as the window width W (i) in that frame. Where d
_max is the maximum value of the control data amount that can be obtained by performing an operation to minimize the audio data rate in one frame.

Therefore, the control data amount required for the window width W (i), W (i) (DD- (i)) / N
(I) is always less than or equal to d _max, and the frame in which the audio data rate can be forcibly minimized, which can occur in the window, can be limited to at most one frame.

In general, in a variable rate codec, it is desirable not to forcibly lower the audio quality as continuously as possible. Thus, according to the embodiment of the present invention, the operation for forcibly reducing the maximum audio rate is performed. Can be provided at intervals.

(Fifth Embodiment) FIG. 7 shows a schematic configuration of a mobile communication terminal using a multiplexer according to a fifth embodiment of the present invention. This embodiment is different from the fourth embodiment already described with reference to FIG. 6 in that a rate comparison unit 19 and an audio rate storage unit in which an accumulation window control determination unit 18 is provided instead of the accumulation window control unit 16 are provided. Part 20
Is newly provided. The configuration of the other parts of the fifth embodiment is the same as that of the fourth embodiment already described, and the duplicate description will be omitted.

For example, in a CDMA cellular system, the average voice data rate is 40% of the communication capacity.
Is said to be. The speech rate storage unit 20 corresponds to such a value, and stores an average amount of audio data R _v per frame as a constant, set.

When certain control data having a data amount D is to be transmitted in N frames, the cumulative window control judging unit 18 calculates the cumulative control data at the head of an arbitrary frame i in the N frames. The accumulated control data transmission amount D (i) stored in the transmission amount storage unit 11 is read, and the value is sent to the rate comparison unit 19.

In each frame, the rate comparing section 19 reads R _v read from the audio rate storing section 20, D (i) sent from the cumulative window control judging section 18, and the number N (i) of remaining frames including that frame. From (D-D
(I)) / N (i) − (R _f −R _v ) is calculated and returned to the cumulative window control determining unit 18. Here, _Rf is the data amount per frame including the voice data and the control data. Where (D−D (i)) / N (i) − (R _f −
R _v ) is the difference between the control data rate required in this frame and the expected value of the control data rate determined from the average audio data rate.

If the required data rate in this frame is lower than the expected value of the control data rate, the probability of not operating the audio data rate is higher than the probability of operating the audio data rate. Therefore, it is statistically more advantageous not to operate the audio data rate under such conditions.

[0068] Therefore, only when the result from the cumulative window control determination unit 18 rate comparing circuit 19 is not negative, like the accumulation window control unit 16 in the fourth embodiment, the frame than the window width calculation section 17 window width W of
(I) is read out, and the past W (i) including the frame is read out.
Control data in (DD- (i)) W
(I) The maximum audio data rate is manipulated in the last frame of the window or in a plurality of frames in a continuous window including the last frame so as to secure at least / N (i).

When the result from the rate comparing unit 19 is negative, the cumulative window control determining unit 18 determines that the control data amount in the past W frames including that frame is (DD- (i)).
Even if it is less than W (i) / N (i), the operation of the audio data rate is not performed.

As described above, according to the above embodiment of the present invention, when the required control data rate is lower than the expected value, the maximum audio rate is forcibly set as compared with the fourth embodiment. The amount of reduction can be reduced, and voice quality degradation can be further reduced. (Sixth Embodiment) FIG. 8 shows a schematic configuration of a mobile communication terminal using a multiplexing device according to a sixth embodiment of the present invention. This embodiment differs from the fifth embodiment described with reference to FIG. 7 in that an audio rate statistic calculation unit 21 is provided instead of the audio rate storage unit 20. The configuration of the other parts of the sixth embodiment is the same as that of the fifth embodiment already described, and the duplicate description will be omitted.

The voice rate statistic calculation unit 21 calculates the initial value R _vinit of the average voice data amount per frame at the start of operation.
And an integer constant n of 2 or more. R _vinit is, for example, CDMA as described in the fifth embodiment.
In cellular cellular systems, this is equivalent to 40% of the communication capacity.

The voice rate statistic calculation unit 21 calculates the voice data amount R of one frame from the variable rate codec 4.
_vsample is received, and (n-1) R _vinit / n + R
The _Vsample / n is calculated and set as the average amount of audio data R _v, since, reads the R _Vsample in each frame,
(N-1) by calculating the value of _{R v / n + R vsample /} n, continue to update the value of the sequential average amount of audio data R _v. Note that, in a frame in which the maximum audio data rate is operated, R
Do not update the value of _v .

The average voice data amount is slightly different depending on the speaker. If this value is set higher than the actual value, the required control data rate calculated by the rate comparing unit 19 and the expected value of the control data rate are calculated. The value of the difference increases, and the probability that an unnecessary audio data rate operation is performed increases. Also,
If the average audio data volume is set lower than the actual value, the difference between the required control data rate and its expected value will be smaller, and more control data volume may remain even near the transmission time limit. A situation arises where the performance is statistically increased, and thus the maximum audio data rate must be continuously reduced.

According to the above embodiment of the present invention, the probability that an unnecessary audio data rate operation is performed is minimized by monitoring and updating a more statistically correct average audio data rate, and The possibility that the maximum audio data rate must be continuously reduced near the transmission time limit can be reduced.

[0075]

As is apparent from the above description of the embodiment, the present invention according to claim 1 has a maximum control data transmission amount only when there is a possibility that the cumulative control data transmission amount crosses the minimum cumulative control data transmission amount curve. Since the audio data rate is controlled, there is an effect that it is possible to guarantee that the transmission of the control data is completed within the time limit while reducing the audio quality deterioration.

Further, the invention according to the second aspect absorbs the stochastic fluctuation of the voice data rate due to sound and non-voice by the window width, and suppresses the deterioration of the voice quality due to the forcible reduction of the maximum voice data rate. Since the control data can be minimized and the control data is secured in a window by a certain amount or more, it is possible to guarantee that the transmission of the control data is completed within the time limit.

Further, according to the third aspect of the present invention, when frames in which the control data rate can be sufficiently secured continue to some extent due to the silent state, the required control data rate thereafter becomes low, and therefore the maximum audio data rate is reduced. There is an effect that the possibility of operation can be reduced and the deterioration of voice quality can be reduced.

According to the fourth aspect of the present invention, since the number of frames that can be generated in a window and whose audio data rate is forcibly minimized can be limited to at most one frame, the operation of forcibly reducing the maximum audio rate is performed. This has the effect that the intervals can be provided.

Further, when the required control data rate is lower than the expected value, the forcible reduction of the maximum voice rate can be reduced, and the voice quality degradation is reduced. It has the effect that it can be done.

Further, according to the present invention, the probability that an unnecessary audio data rate operation is performed is minimized by monitoring and updating a more statistically correct average audio data rate. This has the effect of reducing the possibility that the maximum audio data rate must be continuously reduced near the time limit.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a mobile communication terminal using a multiplexing device according to a first embodiment of the present invention;

FIG. 2 is a graph showing a relationship between a minimum accumulated control data transmission amount curve and an accumulated control data transmission amount used in the description of the first embodiment of the present invention;

FIG. 3 is a block diagram showing a schematic configuration of a mobile communication terminal using a multiplexing device according to a second embodiment of the present invention;

FIG. 4 is a block diagram showing a schematic configuration of a mobile communication terminal using a multiplexing device according to a third embodiment of the present invention;

FIG. 5 is a table showing a relationship between a control data transmission amount and a cumulative control data transmission amount of a frame used in the description of the third embodiment of the present invention;

FIG. 6 is a block diagram showing a schematic configuration of a mobile communication terminal using a multiplexing device according to a fourth embodiment of the present invention;

FIG. 7 is a block diagram showing a schematic configuration of a mobile communication terminal using a multiplexing device according to a fifth embodiment of the present invention;

FIG. 8 is a block diagram showing a schematic configuration of a mobile communication terminal using a multiplexer according to a sixth embodiment of the present invention;

FIG. 9 is a block diagram showing a schematic configuration of a mobile communication terminal using a multiplexing device in a conventional example;

FIG. 10 is a graph showing the relationship between the amount of audio data for each frame and the amount of control data for each frame used in the description of the conventional example.

[Explanation of symbols]

 Reference Signs List 1 antenna 2 transmission unit 3 multiplexing unit 4 variable rate codec 5 microphone 6 control data unit 7 reception unit 8 separation unit 9 audio decoder 10 speaker 11 cumulative control data transmission amount storage unit 12 lowest cumulative control data transmission amount curve storage unit 13 cumulative data Amount comparison unit 14 Window control unit 15 Window width storage unit 16 Cumulative window control unit 17 Window width calculation unit 18 Cumulative window control judgment unit 19 Rate comparison unit 20 Audio rate storage unit 21 Audio rate statistic calculation unit 30 Minimum cumulative control data transmission Volume curve 31 Cumulative control data transmission volume 100 Audio rate control unit 101 Audio data volume per frame 102 Control data volume per frame 103 Frame number 104 Data volume

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) H04J 3/00-3/26 H04L 5/22-5/26 H04B 14/00 JICST file (JOIS)

Claims (6)

(57) [Claims] 1. An audio data coded by a variable rate codec described below is inserted for each time-divided frame, and when there is control data sent from a control data section described later, a free space of the frame is provided. A multiplexing unit that multiplexes the voice data and the control data by inserting a part of the control data into the multiplexing unit, a control data unit that generates control data to be transmitted such as call control information and sends the control data to the multiplexing unit, At a variable rate codec that has a variable rate codec that forcibly reduces the maximum audio data rate allowed for audio data by a designated amount when instructed. If it is to be multiplexed and transmitted by the frame at the time limit, the minimum accumulated control data from the time of the control data generation to the time limit A minimum cumulative control data transmission amount curve storage unit that presets and stores a transmission amount as a minimum cumulative control data transmission amount curve that is a function of time, and stores a cumulative total of control data amounts actually transmitted since the control data was generated. The accumulated control data transmission amount storage unit and the difference between the accumulated control data transmission amount notified from the accumulated control data transmission amount storage unit and the value of the minimum accumulated control data transmission amount curve in each frame from the time of generation of the control data to the time limit. A multiplexing device comprising: a cumulative data amount comparison unit that determines to forcibly reduce a maximum audio data rate and instructs a variable rate codec. Wherein said minimum cumulative control data transmission amount curve storage unit, the cumulative control data transmission amount storage unit, and instead of the accumulated data amount comparator, when the control data is generated, a certain one or more integer constant A window width storage unit that sets and stores a window width, and instructs a variable rate codec such that the average control data rate of a number of past frames equal to the window width including the frame in each frame is always equal to or greater than a certain value. The multiplexing device according to claim 1, further comprising a window control unit. 3. The control apparatus according to claim 2, wherein said window width storage unit includes a control data generating unit.
Stores the total amount of control data actually transmitted from birth
A cumulative control data transmission amount storage unit for calculating the remaining control data amount from the cumulative control data transmission amount notified from the cumulative control data transmission amount storage unit in each frame instead of the window control unit. And the control data rate of the past frames of the number equal to the window width including the frame is equal to or more than the necessary control data rate obtained from the remaining control data amount and the remaining time until the transmission control time of the control data. 3. The multiplexing apparatus according to claim 2, further comprising a cumulative window control unit for instructing a variable rate codec to forcibly reduce the maximum audio data rate of the frame so that 4. The control data amount required in the window in each frame instead of the window width storage unit is the maximum control data amount that can be obtained by performing an operation to minimize the audio data rate in one frame. A window that updates the window width for each frame so that it is less than or equal to the value, so that the number of frames in which the audio data rate takes the lowest value that can occur in each window can be made at most one. 4. The multiplexing device according to claim 3, further comprising a width calculating unit. 5. An accumulation window for instructing a variable rate codec to forcibly reduce the maximum audio data rate of the frame in accordance with a result calculated and reported by a rate comparison unit described later, instead of the accumulation window control unit. a control determination unit, and the speech rate storage unit for storing sets the average audio data rate set in advance, the expected value of the control data rate obtained from the average audio data rate read from the speech rate storage unit in each frame 5. The multiplexing apparatus according to claim 4, further comprising: a rate comparing unit that obtains a difference between required control data rates and reports the difference to the cumulative window control determining unit. 6. An audio rate statistic calculation unit that obtains statistics of an audio data rate encoded by a variable rate codec in each frame and updates an average audio data rate, instead of the audio rate storage unit. The multiplexing device according to claim 5, wherein: