JPH0267846A - Voice packet transmission control system - Google Patents

Abstract

PURPOSE:To improve the voice quality by performing measurement related to the signal, which indicates whether packet reception is possible or not, to discriminate the degree of congestion of a packet network and determining prescribed packets to be abandoned in accordance with this discrimination result to dynamically control the packet transmission volume. CONSTITUTION:A proportion of packet reception inhibition is calculated by a packet network reception inhibition time counting part 80, and a packet abandonment rate setting part 82 obtains a packet abandonment rate corresponding to the calculation result. A packet itself abandoning part 18 retrieves an abandonment table 19 by the packet abandonment rate set by the packet abandonment rate setting part 82 to determine packets to be abandoned so that the reduction of voice quality is minimized. Consequently, packets to be abandoned are dynamically determined in accordance with the congestion state of a packet network 20 by the packet itself abandoning part 18. Thus, the degradation of voice quality is minimized to improve the voice quality.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a voice packet assembly in which packets are assembled based on voice signals and the packets are dynamically discarded according to the congestion regulation state of the packet network. This relates to transmission control methods.

[Conventional technology]

In general, a packet network sends a signal (hereinafter referred to as a packet reception permission/disapproval signal) to indicate whether or not a packet can be received or not depending on the degree of congestion within the network. Notify the packet terminal. The packet terminal sends or stops sending packets in response to this notification signal, and the amount of packets sent to the packet network is forcibly regulated.

When packet transmission is restricted, a possible method is to temporarily accumulate transmission data like e-mail, and then transmit the accumulated transmission data in packets after the restriction is lifted. However, when the transmission data is audio data (audio signal), immediacy is required, so when audio data is stored once, the delay in storage time is accumulated each time it is stored.
This has the disadvantage that the audio transmission delay time gradually increases.

To deal with this drawback, it is necessary to self-discard the accumulated audio data as appropriate to ensure immediacy. Concerning this self-discarding, there are a method of self-discarding at appropriate intervals, a method of self-discarding when a packet transmission restriction occurs, and the like. However, with either method, packets are carelessly discarded, causing discomfort due to audio interruptions, two-word beginnings, two-word endings, etc., and as the discard rate increases, it becomes difficult to understand the content of the conversation. It has the following drawback.

By the way, as a high-quality encoding method for audio signals,
For example, there is CCITT Recommendation G, 722.

This CCITT Recommendation G, 122? The encoding method based on $ is 64 kbps subband ADPCM method 2,
64kb of audio signal in the frequency band of 50Hz to 7kHz
It is capable of high-quality 8-bit encoding in PS, and is used in teleconferencing systems that reproduce high-quality audio and a sense of realism.

Also, the 8-bit code in this encoding method is emb
edded code is used. This embedde
The d code has a characteristic that no sudden deterioration of voice quality occurs even if two or three bits in the 8-bit code are missing.

As a voice packet transmission method that utilizes this characteristic, the Institute of Electronics, Information and Communication Engineers, Study Group Material 1NS7-81 (1987
゜12.24) There are methods described on pages 1 to 6.

According to this audio packet transmission method, 8-bit emb
Divide the edded code into every 2 bits and extract the corresponding 2 pintos from multiple consecutive 8-bit codes,
They are aggregated to generate four packets.

The degree of influence (level) on the quality due to the loss of each generated packet differs from packet to packet, and audio packet transmission systems that take advantage of this property have been considered.

Problem to be solved by the invention C] By the way, in the conventional method described above, when the packet network becomes in a state of congestion, in addition to discarding within the packet network,
A situation arises in which the packet network does not accept input voice packets. When this state is viewed from the packet terminal, the packet discard rate changes drastically (from 0% to 100%).
), and the problem was that the amount of packets sent to the packet network could not be controlled.

If the amount of packets sent to the packet network is not optimal, more packets than necessary or packets will be discarded carelessly, resulting in less than optimal voice quality. Therefore, there has been a need for a method that can improve voice quality by detecting the degree of packet network congestion and dynamically controlling the amount of packets sent.

The present invention was created in view of these points, and an object of the present invention is to provide a voice packet transmission control method that can improve voice quality.

[Means to solve the problem]

FIG. 1 is a configuration diagram of the voice packet transmission control method 2 of the present invention.

In the figure, the voice packet transmission control system of the present invention includes a measuring means for measuring a packet reception permission/disapproval signal indicating whether or not a packet can be received supplied from a packet network, and based on the measurement result by this measuring means. A discard rate setting means that determines the degree of congestion of a packet network and sets a packet discard rate, a discard table that defines the relationship between the packet discard rate and a discard method, and a packet discard rate set by the discard rate setting means. Accordingly, the packet discarding means discards predetermined packets based on the discard table.

[Function] The measuring means measures the packet reception permission/denial signal indicating whether or not packet reception is permitted or not supplied from the packet network, and the degree of congestion of the packet network is determined according to this measurement result. The packet discard rate is set by The packet discard means searches the discard table based on this packet discard rate, determines a discard method, and discards a predetermined packet.

In the present invention, the degree of congestion of the packet network is determined by measuring the packet reception permission/denial signal indicating whether or not the packet can be received, and the packet is discarded in accordance with the result of this determination.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 2 is a schematic configuration diagram of a packet network in an embodiment of the present invention.

In the figure, an audio signal supplied to an input terminal 10 is transferred to a packet generator 12. The packet generation unit 12
After converting the audio signal into a predetermined code, it assembles a packet and notifies the bucket network 20 that the packet will be sent. The yi 20 notifies the packet generation unit 12 of a packet reception permission/disapproval signal 70 indicating whether or not the packet can be received depending on the degree of congestion inside the steel.

When packet reception is permitted, the packet generation unit 12
sends the packet 50, and if it is not permitted, stops sending the packet 50 until permission is granted.

The bucket 14M20 performs processing such as delaying and discarding the received packet 50, and returns the packet 6.
It is transferred to the packet reproducing unit 40 as 0. The packet playback unit 40 disassembles the packet 60 to obtain audio data and converts this audio data into an audio signal, which is output from the output terminal 30.

Further, FIG. 3 shows the configuration of an embodiment when focusing on the bucket 1-discarding operation. A packet self-discarding section 18 is provided after the packet generating section 12 in FIG. 2 to discard packets.

In FIG. 3, I4 is an analog-digital converter (
16 is a packet assembly section, 17 is a buffer memory, and 18 is a packet self-discard section.

A/D for the audio signal a supplied from the input terminal 10
The conversion unit 14 converts, for example, an 8-bit code pl+P2+P31P4, compliant with CCITT recommendation G722, .
...is generated. This 8-bit code is sequentially stored in the buffer memory 17 in the packet assembling section 16. Thereafter, the packet assembling unit 16 generates four packets 81 with different degrees of influence (level) on voice quality due to packet loss.
+, e+z+ e13, e (assuming that 2 bits of each consecutive 8-bit code are extracted to assemble 4 packets) and transferred to the packet self-discard unit 18. Similarly, the packet assembling unit 16 assembles the packet e21. e 22+
e23. Assemble e 24 and packet self-discard unit 1
Transfer to the date.

The packet self-discard unit 18 estimates the degree of congestion of the packet network 20 according to the packet reception permission/disapproval signal 70 supplied from the packet network 20. Based on this estimation result, a packet discard rate that defines packets ffi to be sent to the packet network 20 is calculated, and based on this calculation result, packets are thinned out and discarded. In Figure 2, the packet discard rate is set to 25%, and the packet enl(n・1
,2. ) are thinned out and discarded, and the remaining packets en
□-en3. e, , 4 (n=L2. . . ) are sent as packet 50 to packet m20.

FIG. 4 shows a detailed configuration for controlling the discard operation in the packet self-discard section 18 of FIG.

In FIG. 4, 19 is a discard table, 21 is a packet reception permission/disapproval signal terminal, 22 is a packet network input terminal, 80 is a packet network unreceivable time counter, 82 is a packet discard rate setting unit, and 84 is a control unit. It is.

The packet generation unit 12 assembles packets based on the input audio signal according to instructions from the control unit 84.

In addition, the packet network unreceivable time counting unit 80 controls the control unit 8.
4, the reception time of the portion indicating that packet reception is not permitted in the signal supplied from the packet reception permission/denial signal terminal 21 of packet y420 is measured, and this measurement result is sequentially sent to the packet discard rate setting unit 82. Transfer to.

FIG. 5 shows an example of the packet reception permission/denial signal 70 supplied from the packet reception permission/denial signal terminal 21. In the figure, a high state of the signal indicates that packet reception is not permitted, and a low state of the signal indicates that packet reception is permitted.

The packet network reception unavailable time counting unit 80 measures each of the reception times L+, tz, and L3 of the portion indicating that packet reception is not permitted.

Further, when the packet network unreceivable time counting unit 80 receives the packet reception permission/disapproval signal 70, it notifies the packet generation unit 12 of this fact as an instruction to stop/restart packet transmission. The packet generation unit 12 stops or resumes sending the packets being transferred to the packet network input terminal 22 in response to this notification.

The packet discard rate setting unit 82 calculates the cumulative sum of the measurement results within a predetermined time based on the measurement results transferred from the packet network unreceivable time counting unit 80 according to instructions from the control unit 84. The value obtained by dividing the calculated cumulative sum by the unit time is determined as the degree of convergence of the packet y420. Furthermore, a packet discard rate is set according to this degree of comparison. For example, each reception time tl, t2 . The congestion degree of the packet network 20 is obtained by dividing the sum of t3 by the unit time to (1.-1-1.÷t3)/lo.

The packet self-discarding unit 18, according to instructions from the control unit 84,
Based on the discard table 19, the packet discard rate setting unit 8
Determine the discard method according to the packet discard rate set in step 2.

Examples of the contents of the discard table 19 are shown in Tables 1 and 2.

(Margin below this page) Table 1 (n = 1.2. ・ ・ ・ ・Qz
<Q3 <Qa), "R" indicates the packet discard rate (unit: [%]), and 'X and OJ indicate the presence or absence of discard.

Table 1 shows the relationship between packets to be discarded and the degree of influence on voice quality. Furthermore, Table 2 shows the relationship between the packet discard rate R and the degree of influence on voice quality.

For example, if the discard rate is R-25 [%] as shown in FIG.
With reference to Tables 1 and 2), control is performed to discard packets enl corresponding to degree Q, where the impact on quality due to packet discard is the smallest.

Next, the packet generation section 12 discards the relevant packet under the control of the packet self-discard section 18 according to the instruction from the control section 84 and supplies the remaining packet to the packet network input terminal 22 of the packet network 20 .

When supplying this packet, the packet generation unit 12:
The transmission of packets is controlled in accordance with the instruction to stop/restart packet transmission notified from the packet network unreceivable time counting unit 80.

FIG. 6 shows an application example of packet discard.

(a) shows a method of supplying packets that have undergone packet discard processing to the packet network 20 as shown in FIGS. 2 and 3. In addition, in (b), the packet discard permission designator h
,, (n=L2...) is added, and the packet network 20
It shows a method for discarding data according to the degree of network congestion within the network.

In this way, the packet network unreceivable time counting unit 80 calculates the rate of packet reception disallowance, and the packet discard rate setting unit 82 determines the packet discard rate according to this calculation result. The packet self-discard unit 18 searches the discard table 19 based on the packet discard rate set by the packet discard rate setting unit 82, and determines discarded packets to minimize the deterioration of voice quality.

Therefore, packets to be discarded can be dynamically determined by the packet self-discard unit 18 according to the congestion state of the packet network 20, and it is possible to improve voice quality by minimizing deterioration of voice quality. becomes.

In addition, in the example of this explanation, four packets are
Although the packets are generated as blocks, the number of packets in the block may also be increased by increasing the amount of data stored in the buffer memory 17. In this case, the number of influence degrees Q increases in accordance with the number of packets, and the step width of the packet discard rate R can be made smaller.

〔Effect of the invention〕

As described above, according to the present invention, the degree of congestion of the packet network is determined by measuring the signal indicating whether or not a packet can be received, and a predetermined packet to be discarded is determined according to the result of this determination. It is possible to dynamically control the amount of packets sent and improve voice quality.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the voice packet transmission control system of the present invention, Fig. 2 is a schematic diagram of a packet network of an embodiment, Fig. 3 is an explanatory diagram of packet discard of an embodiment, and Fig. 4 is an implementation example. FIG. 5 is an explanatory diagram of a packet reception permission/disapproval signal, and FIG. 6 is a detailed explanatory diagram of the present invention. In the figure, 10 is an input terminal, 12 is a packet generator, 14 is an analog-digital converter, 16 is a packet assembly unit, 17 is a buffer memory, 18 is a packet self-discard unit, 19 is a discard table, and 20 is a packet network , 21 is a packet reception permission/disapproval signal terminal, 22 is a packet network input terminal, 30 is an output terminal, 40 is a packet reproducing unit, 50, 60 is a packet, 70 is a packet reception permission/disapproval signal, 80 is a packet m 82 is a bucket/node discard rate setting section; and 84 is a control section. Figure Figure Figure

Claims (1)

[Claims] (1) A measuring means for measuring a signal indicating whether or not packets can be received supplied from the packet network, and based on the measurement results by the measuring means, determining the degree of congestion of the packet network and setting the packet discard rate. a discarding rate setting means for discarding a packet, a discarding table defining a relationship between a packet discarding rate and a discarding method, and discarding a predetermined packet based on the discarding table according to the packet discarding rate set by the discarding rate setting means. What is claimed is: 1. A voice packet transmission control system comprising: packet discarding means for discarding packets;