JP2001244975A - Device and method for multiplex audio packet transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce lowering of an audio quality caused by packet delay oscilla tion or packet waste at the time of multiplexing an audio packet to which audio information inputted from a line is converted, when this audio packet is temporarily increased. SOLUTION: This multiplex audio packet transmitter has a multiplex packet control means for generating the audio packet from the audio information, which is inputted from the line by a line correspondent transmission part, except for a soundless state and performing control for multiplexing the packet within the range of a maximum multiplex number provided on the basis of the limit band of a transmission line, a packet buffer means for temporarily storing the audio packet for delaying multiplexing until l the traffic of the other audio packet concerning audio packets is lowered, which are generated beyond the maximum multiplex number, and a packet waste reporting means for generating a signal for reporting packet waste to the receiving side of that line when packets are discarded since the packet buffer means exceeds storage capacity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice packet multiplex transmission apparatus and a voice packet multiplex transmission method for packetizing voice information into code information of a fixed information block, multiplexing and transmitting the first packets of the plurality of channels. .

[0002]

2. Description of the Related Art Conventionally, voice transmission has been shifted from an analog system to a digital system. In the case of telephone transmission using voice that requires real-time characteristics, voice is A / D-converted with digitization. The packet is divided into a predetermined number of bits, transmitted along a line, D / A converted, and transmitted to a target destination.

This voice packet transmission apparatus is described as a first prior art in Japanese Patent Laid-Open No. 5-304509. Conventionally, in this publication, each line-corresponding unit packetizes audio information digitized by a bit string conversion circuit by a pulse coding (PCM) method as it is into 256 bytes each having a predetermined length, and a multiplexing unit for packetizing the audio information. When the sum of the packet amounts exceeds the transmission path capacity, some packets on an arbitrary line have been discarded. In this discarding, in the audio information digitized by the PCM method, the higher bits have a higher specific gravity relating to the amplitude of the audio signal, and if the same amount of information is lost, the higher bits have lower audio clarity.

[0004] In this publication, as shown in FIG.
If the sum of the packet amounts exceeds the transmission capacity, the packet having the smallest bit position number is preferentially discarded.

FIG. 4 is a block diagram showing an outline of the configuration of the voice packet transmission device of the publication. The voice packet transmission apparatus shown in FIG. 4 receives input voice information digitized by the PCM method for each line, divides the input voice information into predetermined lengths, and edits the bits in order from the lowest position to the highest position bit. A bit string conversion circuit 201 and a control unit 206 as bit string conversion means for dividing the input voice information; and a bit position number addition circuit 202 and a control unit 206 for adding a bit position number to the output of the bit string conversion circuit 201, respectively. Based on the detection result of the silence detection circuit 205, the silence detection circuit 205 and the control unit 206 for detecting whether or not the bit section at each position is silence. And a packetization circuit 204 for discarding the silent section and packetizing and outputting the packetized data, a packet information generation circuit 203, and a control unit 206.

The multiplexing unit 230 detects the bit position number of each line from the output of the packetizing circuit 204 as shown in FIG. 5, and based on the detection result, determines if the total amount of packets exceeds the transmission line capacity. The buffer 231 that preferentially discards the packet having the smallest bit position number, the bit position number detection circuit 232, the control circuit 234, and the packet multiplexing circuit 233 that multiplexes and outputs the output of the bit position number detection circuit 232 And

An input audio signal 221 digitized by the PCM method is input to an input terminal 211, and a bit string conversion circuit 201 outputs an input audio signal 2 from the input terminal 211.
21 is divided into a predetermined length (256 bytes). The bit string conversion circuit 201 performs bit conversion on the 256-byte audio information based on the bit string conversion control signal 223 from the control circuit 206. Bit position number addition circuit 2
02 adds the bit position signal 224 output from the control circuit 206 to the 32-byte information for each bit position input from the bit string conversion circuit 201 and outputs the information to the packetizing circuit 204. The packetizing circuit 204 packetizes the information for each bit position input from the bit position number adding circuit 202 by adding control information such as a source address and a destination address created by the packet information generating circuit 203. . On the other hand, the silence detection circuit 20
5 receives the input audio signal 221 and outputs the bit string conversion circuit 2
When the voice information in the section where the processing is performed in step 01 is silent, the packet discarding signal 222 is output to the packetizing circuit, and the packetizing circuit 204 outputs the packet discarding signal 222.
Is input, the packet is discarded, and the packetized information is transmitted to the multiplexing unit 230.

[0008] The multiplexing unit 230 stores the packet transmitted from the line corresponding unit 210 in a buffer 231, and the buffer 231 receives the packet and receives a packet reception signal 24.
1 is supplied to the control circuit 234. The packet once stored in the buffer 231 is transmitted to the bit position number detection circuit 232.
, The bit position number detection circuit 232 detects the bit position number 242 added by the line correspondence unit 210 and supplies it to the control circuit 234. The control circuit 234 calculates the sum of the packet amount input from the line correspondence unit 210. Is larger than the transmission capacity, one of the lines having the smallest bit position number 242 added by the bit position number adding circuit 202 is selected, and the packet discard signal 243 is sent to the bit position number detecting circuit 232 of that line. Output. If this results in
If the sum of the multiplexed packet amounts, that is, the sum of the packet amounts from the line corresponding unit 210 excluding the discarded packets still exceeds the capacity of the transmission line, the packet discard processing is similarly performed for the other lines. Will be It should be noted that packet discarding processing is not performed on the same line as continuously as possible. In this way, packets including bits close to the least significant bit of the PCM original information are discarded preferentially.

This is because, in the code according to the PCM system, the closer to the least significant bit, the smaller the amplitude component of the voice is. Therefore, the amount of error of the signal component when the packet is discarded is reduced. I have less.

Further, as a second prior art, Japanese Patent Laid-Open No.
According to Japanese Patent Publication No. 6383, the configurations of a line-compatible transmitting unit and a line-compatible receiving unit are the same as those shown in FIG. 4. In the same publication, when discarding voice packets of some lines due to line congestion or the like. In order to reduce the decrease in voice intelligibility at the receiving side, if the sum of the packet amounts exceeds the transmission capacity, the voice type information output from the voice type information detection circuit gives priority to voice packets that are vowel parts. Was discarded.

[0011]

However, in the above-described first prior art voice packet transmission apparatus, the voice coded data of the coding system in which the strength of the signal component does not directly correspond to the bit string as in the PCM system. When packetization is performed, the drop in voice quality when a packet composed of low bit positions of data is discarded is not necessarily smaller than that of a packet composed of high bit positions. Not exclusively.

[0012] In the second method of discarding voice packets according to the prior art, when the voice information is divided into a vowel portion and a consonant portion, and a coding method other than packetization is applied, for example, a high When a packet is generated by the efficiency compression coding method or the like, the priority of packet discard cannot be determined based on the same criteria. Furthermore, in any of the prior art methods, the probability of packet discarding in each multiplexed channel is statistically equal, so that when the packet discarding frequency occurs, the voice quality of all the channels deteriorates. there is a possibility.

[Object of the Invention] The present invention discriminates between a sound part and a silent part of audio information input from a line, and then multiplexes and transfers only the sound information and the silence detection information by packet multiplexing. Along with the efficient use of the transmission path, when the traffic of voice packets temporarily increases, the packets of the new conversation channel are temporarily stored in the packet buffer, and the multiplexing timing is delayed to reduce If the packet is discarded because the quality degradation has been minimized and the packet buffer capacity has been exceeded, the sender is notified of this, so that the no-communication state is maintained and the overall communication quality is reduced as much as possible. The aim is to reduce it.

[0014]

A voice packet multiplex transmission apparatus according to the present invention generates a voice packet from a voice information input from a line in a line-compatible transmitting unit except when there is no sound, and transmits the voice packet to a limited band of a transmission line. Packet multiplexing control means for performing control for multiplexing packets within a range of the maximum multiplexing number provided based on the multiplexing number, and multiplexing for voice packets generated exceeding the maximum multiplexing number until the traffic of other voice packets is reduced. Packet buffer means for temporarily storing voice packets for delay and, when a packet is discarded because the capacity of the packet buffer means is exceeded, a signal for notifying the receiving side of the line of the packet discard is generated. Packet discard notification means.

The present invention also relates to a voice packet multiplex transmission apparatus for multiplexing voice packets via a line and transmitting the multiplexed voice packets. A silence detection unit, encoding is performed for the speech portion based on the result of the discrimination by the speech / silence detection unit, and silence detection information is generated only at the start of silence for the silence portion. A speech encoding unit that does not perform encoding, and information for identifying a channel and information for identifying speech / non-speech are added to the encoded speech information and the silence detection information output from the speech encoding unit. A packetizer for performing first packetization, and a packet for storing the first packet in order to delay the start of multiplexing of the first packet output from the packetizer. A buffer unit; a second packet assembling unit that multiplexes the first packet output from the packetizing unit or the packet buffer unit, multiplexes the multiplexed packet into a second packet, and outputs the multiplexed packet to a transmission path; The number of packets of the second packet multiplexed by the packet assembling unit and the first packet output from the packetizing unit from the channel of the first packet stored in the packet buffer unit, A packet multiplexing control unit that controls accumulation in the buffer unit and controls the start of multiplexing of untransmitted packets of the first packet in the packet buffer unit.

Further, according to the present invention, in a voice packet multiplex transmission method for multiplexing voice packets via a line and transmitting the multiplexed voice packets, the transmitting unit for outputting voice signals from a plurality of lines includes voice information input from the lines. Based on the result of the discrimination between a sound part and a silent part, the sound part is encoded and output as audio information based on the discrimination result. In the subsequent silence state, the silence detection information is output without performing encoding, and information for identifying a channel indicating the line and speech / non-speech information for the audio information and the silence detection information.
Packetization is performed by adding information for identifying silence.
In order to delay the start of the multiplexing of the packetized packet, the packet is stored, and the packet output from the buffer unit storing the packetized or the packet is multiplexed, divided into ATM cells, and transmitted to the transmission line. Output,
The packet multiplexing control unit for controlling the transmitting unit includes the AT
Performing control to accumulate the packet to be packetized in the buffer from the number of packets to be multiplexed in the M cell and the channel of the packet accumulated in the buffer;
In addition, it is characterized in that the start of multiplexing of untransmitted packets in the buffer is controlled.

[Operation] According to the present invention, referring to FIG. 1, the packet multiplexing control means 30 comprises: a voice packet output from the line corresponding transmission unit 10 corresponding to each line; 20. The number of voice packets already stored in the packet buffer 20 is monitored, and voice packets newly generated exceeding the maximum multiplexing number or voice packets of the line already stored in the packet buffer 20 are line-compatible. When output from the transmission unit 10, those voice packets are accumulated in the packet buffer means 20 as far as the capacity is possible.

Here, when voice packets exceeding the capacity of the packet buffer means 20 are generated, the packet multiplexing control means 30 instructs the line corresponding transmission unit 10 to discard those voice packets. At the same time, it instructs the packet discarding notification means provided in the line reception corresponding unit 60 to transmit a signal for notifying the packet discarding to the receiving side of the line corresponding to the discarded packet.

If the number of multiplexed audio packets is less than the maximum number of multiplexed packets, the packet multiplexing control means 30 multiplexes the untransmitted audio packets stored in the packet buffer means 20. Start.

As described above, when traffic exceeding the limited bandwidth is temporarily generated, the start of packet multiplexing of newly generated traffic is delayed, thereby deteriorating communication quality due to packet discarding and delay fluctuation. As much as possible. Further, when discarding a packet, the sender is notified of the packet discard, and the communication quality of other communications is minimized.

[0021]

Embodiments of the present invention will be described in detail with reference to the drawings.

First Embodiment (1) Description of Configuration A first embodiment of the present invention will be described with reference to the drawings.

Referring to FIG. 1, in a first embodiment of the present invention, a means for judging a sound / non-speech state of a sound / non-speech state of input voice information from a line on a transmission side to a transmission line 2 is described.
Based on the silence detection unit 13 and the speech / silence determination result of the speech / silence detection unit 13, the speech information is encoded in the speech state, and the silence detection information is generated only at the start of silence in the silence state. Then, the speech encoding unit 11 of the means that does not perform the subsequent encoding, and the speech identification information encoded by the speech encoding unit 11 and the silence detection information include information for identifying a channel and information for identifying speech / non-speech. The packetizing unit 12 of the means for adding and packetizing is provided in the line corresponding transmitting unit 10 of the packet transmitting processing means corresponding to the line.

On the other hand, when a packet exceeding a preset multiplexing capacity occurs on the transmission line 2, a packet buffer unit 20 for storing the packet in a buffer is provided to delay the multiplexing timing. ATM cell assembling section 40 for multiplexing packets from a line and packets stored in a buffer and sending the multiplexed packet to a transmission line.
It is determined whether packets are stored in the packet buffer unit 20 based on the voiced / silent state of each line and the multiplexing capacity of the transmission line, and a determination is made to start multiplexing of untransmitted packets in the packet buffer unit 20. Packet multiplexing control means 30 for deciding to discard packets based on the available capacity of
Having. Here, when outputting to the ATM network, AT
The M-cell assembling unit 40 is used, but the public network or I
When using the SDN network, the packet buffer unit 2
0 is set as a first packet, and the result of multiplexing the first packet is set as a second packet.
The packet assembling section 40 of FIG. Accordingly, in this case, the output to the transmission path 2 or the input from the transmission path 2 operates as the second packet in the same manner as the ATM network.
Hereinafter, the transmission path 2 will be described using an example of an ATM network.

Further, an ATM cell decomposing unit 50 for separating the multiplexed packet from the transmission line 2 into a line corresponding receiving unit 60 of the line corresponding packet receiving processing unit based on the identification information of the channel. Extract coded audio information and silence detection information from sound / silence identification information,
The information is sent to the audio decoding unit 62 of the means for decoding the encoded audio information, or to the silence reproducing unit 63 of the means for reproducing the silence from the silence detection information, and the decoded audio information or the silence reproduction information is A depacketizing unit 61 is a unit for controlling the selecting unit 65 of the unit for selecting and outputting to the line based on the information of sound / no sound.

Further, in addition to the means for realizing voice information communication between these devices, the apparatus has a function relating to processing when a packet is discarded at the time of packet multiplexing. A push button (PB) signal generator 64 for generating a packet discard notification signal to be output toward the line when a packet discard of a certain line is determined; A selection unit 65 is provided for selecting a packet discard notification signal from the reproduction information and outputting it to the line. This push button (PB) signal generation unit 64 is a sound that generates a noteworthy sound as a warning sound or a caution sound.
Other sounds may be used, for example a dual tone generator of a similar sound generator.

(2) Description of Operation In the first embodiment of the present invention, for voice information input from a line, a sound part and a silent part are discriminated, and a sound part is always encoded. However, for silence parts, silence detection information is generated only at the start of silence, and thereafter, encoding is not performed. Communication can be performed.

In general, the distribution of occurrence of silence in a voice call has a statistical property. Therefore, when such communication is multiplexed, the transmission bandwidth varies. In the packet multiplexing control process, when the amount of audio information packets exceeds the bandwidth of the transmission line set in advance, discarding of packets due to a temporary increase in the transmission band is minimized. Therefore, the multiplexing process of a new conversation is delayed.

Specifically, when the number of packets to be multiplexed exceeds a predetermined upper limit value, the beginning of a voiced packet newly generated from a silent state is stored in a buffer, and packet transmission from the buffer is performed by multiplexing. Starts after a vacant number of packets is generated. This conversation is multiplexed via the buffer until a silence state occurs next time, so that a delay always occurs during that time. Similarly, when a new conversation occurs, the accumulation of packets in the buffer is started in the same manner. However, if the buffer has insufficient free storage capacity, the packet is discarded, and a packet discard notification signal is sent to the receiving side of the line. Is sent. The talker who has received the packet discard notification signal temporarily suspends the conversation, so that the conversation can be started again if the buffer storage capacity becomes available.

[0030]

EXAMPLES [First Example] (1) Description of Configuration In order to explain the above-described embodiment of the present invention in more detail, the first example of the present invention will be described in more detail with reference to the drawings. Will be described.

FIG. 1 is a block diagram showing the configuration of a voice packet multiplex transmission apparatus according to one embodiment of the present invention. The voice packet multiplexing transmission apparatus 1 shown in FIG. 1 compresses voice information input from a line after code compression and silence compression, multiplexes the packets, transmits the multiplexed packets to the transmission line 2 as ATM cells, and performs packet multiplexing from the received ATM cells. This is an audio packet multiplex transmission device that reproduces audio information after separation and sends it out to a line.

The voice information input from the line is input to a sound / non-sound detecting unit 13 constituting the line-compatible transmitting unit 10.
A speech state and a silence state are discriminated for each predetermined section, and according to the speech / silence discrimination result, in the case of a speech state by the speech encoding unit 11, a speech code compressed by PCM encoding or the like is used. In the case of a silent state, silence detection information is generated only at the start of silence by silence compression processing, and subsequent encoding is not performed. The coded audio signal and the silence detection information that have been subjected to the audio code compression are added with channel ID information for identifying a channel and speech / silence information for identifying speech / silence in the packetizing unit 12. Are packetized into a sound packet and a silence detection packet, respectively.

The packet multiplexing control unit 30 monitors the number of channels to be multiplexed, and stores packets of channels for which multiplexing processing needs to be delayed in the packet buffer unit 20 when new multiplexing processing becomes possible. , The packet transmission of the untransmitted channel from the packet buffer unit 20 is started.

The ATM cell assembling section 40 multiplexes the packet from the packetizing section 12 or the packet buffer section 20 of each line according to the instruction of the packet multiplexing control section 30 and divides the packet into a plurality of ATM cells for transmission. A process of transmitting to the road 2 is performed.

The ATM cell disassembly unit 50 processes and transmits the ATM cells in the same manner as described above, contrary to the ATM cell assembling unit 40 which is processed and transmitted by the executed line corresponding transmitting unit 10. A multiplexed packet is reconstructed from the plurality of received ATM cells, and the packet is output to the depacket unit 61 of each line corresponding receiving unit 60 based on the channel ID information added to each packet. The depacket unit 61 outputs a voiced packet to the voice decoding unit 62 from the voiced / silent information added to the packet, and outputs a voiceless detection packet to the voiceless reproduction unit 6.
3 and controls the selection unit 65 for selecting the audio information compressed and decoded by the audio decoding unit 62 and the silence information reproduced by the silence reproduction unit 63, based on the received packet. Output playback audio information to the line. Also, the PB connected to the selection unit 65
The signal generating unit 64 is used for notifying the receiving side of the channel of packet discarding when a packet is discarded due to lack of free space in the packet buffer unit 20 in packet multiplexing processing by the packet multiplexing control unit 30. The PB signal is output to the line when the packet multiplexing control unit 30 controls the packet multiplexing control unit 30 together with the selection unit 65 when a packet is discarded.

(2) Description of Operation Next, the operation of the voice packet multiplex transmission apparatus according to one embodiment of the present invention will be described in more detail with reference to the drawings.

FIG. 2 is a flowchart for explaining the operation of the voice packet multiplex transmission apparatus according to one embodiment of the present invention.

FIG. 3 is a diagram for explaining the packet multiplexing process of the voice packet multiplex transmission apparatus according to one embodiment of the present invention.

When the voice information input from the line is in a sound state, the line corresponding transmitting section 10 periodically outputs a sound packet of a fixed length information block. In the case of a silent state, a silence detection packet to which silence information of the fixed-length information block is added is output at the start of silence, but no packet is output thereafter.

With respect to the band limitation provided in the transmission line 2,
Since the information amount per unit cycle of the voiced packet or the silence detection packet to be output there is a fixed length as described above, the packet band limiting process in the packet multiplexing control unit 30 is performed in the cycle in which the voiced packet is output. Is set as a unit cycle, and the number of channels of packets to be multiplexed is monitored and controlled every cycle so that the number of channels of packets to be multiplexed per unit cycle is equal to or less than a value obtained from the limited bandwidth. Here, the processing flow of the packet multiplexing control unit 30 will be described with reference to FIG.

The packet multiplexing control unit 30 determines whether the voiced packet or the silence detection packet output from the packetizing unit 12 or the packet buffer unit 20 of each line in FIG. The multiplexed channel is determined according to the processing flow of (1). First, in the first condition determination (S11), regarding the channels already stored in the packet multiplexing control unit 30,
The latest packet is always stored at the end of the same channel in the buffer (S16) to ensure that the order of packet output does not change during multiplexing. However, if the free space of the packet buffer unit 20 is insufficient (S13), a PB signal indicating packet discard is sent to the receiving side of the channel (S17), and the packet is discarded (S1).
8).

In the second condition determination (S12), when a voice packet is generated in a new channel, the bandwidth increases. Therefore, the number of channels to be multiplexed in this cycle is verified, and the cycle is continued from the previous cycle. The sum of the number of channels to be transmitted and the number of untransmitted channels reserved in the packet buffer unit 20, that is, the sum of the number of leading voice packets, the number of continuous transmission channels, and the number of buffer reserved channels is larger than the maximum number of multiplexed channels. Only when the number is less than the maximum number of multiplexed channels of the permissible transmission path (No), multiplexing is started for the number of vacant channels, and the packet buffer unit 20 for more channels. accumulate.

On the other hand, if the sum of the first voiced packet, the number of continuous transmission channels, and the number of buffer reservation channels is larger than the maximum number of multiplexed channels (Yes), it is next determined whether or not the packet buffer unit 20 has free space. If the free space of the packet buffer unit 20 is insufficient (No) (S14), a PB signal indicating packet discard is sent to the receiving side of the channel (S17), and the packet is discarded (S18). . If there is free space in the packet buffer unit 20 in step S14, the packet buffer unit 20
The packet is stored in the area of the new channel within
5).

According to the second condition judgment, it is ensured that the channel continuing from the previous cycle is preferentially multiplexed, and the channel generated later is transmitted to the packet buffer unit 20.
Prevents the priority from being given to the channel whose transmission is suspended.

In the third condition judgment (S19), if the number of continuously transmitted channels is less than the maximum number of multiplexed channels (Yes), the untransmitted channels held in the packet buffer unit 20 are reserved. Is started (S20). In the third condition judgment (S19), if the number of continuously transmitted channels exceeds the maximum number of multiplexed channels (No), the ATM cell assembling unit 40 determines in step S19.
The packet is multiplexed with the result of step 20 and transmitted to the transmission line 2 as an ATM cell (S21).

An example of the multiplexed channel determination processing will be described with reference to FIG. FIG. 3 shows an example in which the maximum number of multiplexed channels is set to 3 in an apparatus having four-channel inputs (CH1 to CH4). In addition, a voiced packet (each of 1 to 4 CH) and a silent detection packet (each of 1 to 4 CH) of each channel are distinguished from a silent state as illustrated.

In this example, a certain period (T1 to T1)
5. . ) Is multiplexed in the next cycle and output as an output multiplexed voice packet. The channel CH1 generated in the T6 cycle to the T10 cycle is output.
Since the voice packet or the silence detection packet of exceeds the maximum number of multiplexed channels at the time of multiplexing, the packet is temporarily stored in the packet buffer unit 20 as shown as a pending packet in the packet buffer unit 20 of FIG. It is output two cycles later. However, due to the influence of the channel CH1, no packet discarding, packet fluctuation, or the like has occurred in any other channel.

Here, an example of the operation of the packet multiplexing means often implemented in the conventional voice packet transmission apparatus will be described.
This will be described with reference to FIG. This figure shows an example of an output packet when two different multiplexing methods are used under the same input conditions as in FIG. 3 and the limitation on the maximum number of multiplexed channels. FIG.
Multiplexing example 1 in channel CH1 to channel C
Multiplexing is repeated in the order of H4 except for silence packets,
When the cycle changes, this is a method of multiplexing from the next channel multiplexed in the previous cycle, and packets exceeding the maximum number of multiplexed channels are discarded. In this example, when the maximum number of multiplexed channels is exceeded, packets are discarded with almost the same probability in the channel being communicated, thereby causing the communication quality to be almost uniformly reduced in all channels. Become.

On the other hand, in multiplexing example 2 shown in FIG. 6, the order of multiplexing is the same as in multiplexing example 1, but packets exceeding the maximum number of multiplexed channels are stored in a waiting buffer.
This is a method of sending this packet preferentially in the next cycle. In this example, when the maximum number of multiplexed channels is exceeded (T7 to T11), packet delay fluctuations occur at almost the same probability in the channel under communication, and a means for absorbing the fluctuations is provided in the receiving apparatus. Otherwise, the communication quality with the device will be degraded, or if the state exceeding the maximum number of multiplexed channels continues to be discarded, the packet will be almost equally distributed over all channels. Communication quality will be degraded.

In contrast to the multiplexing examples 1 and 2 shown in FIG. 6, in the present embodiment, as shown in FIG. 3, in order to keep the communication quality at a certain level or more, each block configuration explained in FIG. With the respective functions of the flowchart described with reference to FIG. 2, due to the mutual influence of each channel as described above, it is possible to prevent packet discarding, packet fluctuation, and the like from occurring in that channel.

[Second Embodiment] As a second embodiment of the present invention, an ATM (Asynchronous Transfer Module) shown in FIG.
e: Asynchronous communication mode) The cell assembling section 40 and the ATM cell decomposing section 50 respectively transmit the ATM to the transmission line 2.
Although shown as a functional unit for transferring voice packets using cells, S
When voice packets are transmitted using packet transfer means based on TM (Synchronous Transfer Mode), AT
The M cell assembling section 40 performs only multiplexing of voice packets as a packet assembling section 40 'for STM,
The M cell decomposing unit 50 performs the distribution of the voice packet from the multiplexed voice packet to the line receiving corresponding unit 60 based on the channel ID information as the STM packet separating unit 50 '. Also, the PB signal generation unit 64 generates a busy tone BT signal that has been transmitted for a disconnected call at the time of call setting by a conventional STM-based switching system or the like as a BT signal generation unit 64 '.

Here, the STM system conforms to the unified BI
To establish the SDN standard, SDH (Synchronous Digital Hierarchy), which unifies digital hierarchy,
The interface between the multiplexing device and the transmission path is set to NNI (Ne
PDH before SDH as twork Node Interface)
(Plesiochronous Digital Hierarchy), which is a synchronous transmission module (STM) that multiplexes various signals into transmission signal structures.
And based on STM-N (N = 1,
4, 16), the STM-N has a structure of 270 × N bytes × 9 rows, which is accommodated in 125 μs, and the information area is transmitted as an STM-N payload.

Therefore, the packet assembling unit 4 according to this embodiment is
The multiplexed STM frame at 0 'is assembled at predetermined intervals in units of 125 μs. Also, instead of the ATM cell disassembly unit 50, the packet is disassembled into a desired packet by a packet disassembly unit 50 ′ and transmitted to the depacketizing unit 61.

[Third Embodiment] As a third embodiment of the present invention, an ATM cell assembling unit 40 for transferring a voice packet using an IP packet to the transmission line 2 in FIG. The IP packet assembling unit 40 "performs multiplexing of voice packets and addition of IP header information. The ATM cell decomposing unit 50 separates the multiplexed voice packets from the IP packets as the IP packet separating unit 50" in the Internet, and outputs the channel ID information. The voice packet is distributed to the line receiving corresponding unit 60 based on the above.

The Internet handles multimedia for transmitting not only voice but also image signals and data, and uses TCP / IP (Transmission Control Protocol / In).
Internet protocol according to the protocol of the Internet protocol (fixed length or variable length). In the case of audio or video, real-time transmission may be required. It is preferable that the assembling unit 40 ″ and the IP packet separating unit 50 ″ respond appropriately.

In this case, for example, the packetizing unit 12
The packet handled by the depacketizing unit 61 is treated as a first packet, and the packet transmitted or input by the IP packet assembling unit 40 ″ and the IP packet separating unit 50 ″ is treated as a second packet.

[0057]

As is clear from the above description, the present invention has the following effects.

The first effect is that when the amount of voice packets multiplexed and transmitted to the transmission path exceeds a predetermined bandwidth capacity, the timing for starting multiplexing on a channel in which a new voice packet has occurred is started. In order to delay the delay, packets are temporarily stored in the packet buffer, and multiplexing is started after there is a margin in the bandwidth capacity. This has the effect of minimizing packet discard due to a large increase in the number of multiplexed channels.

That is, when a voice packet of a certain channel is generated, in the channels that have been multiplexed up to now, there is no delay fluctuation waiting for multiplexing, no packet discarding, etc., and the packet is temporarily stored in the packet buffer. This is because packets of the output channel are also transmitted at regular intervals without causing delay fluctuations waiting for multiplexing after the start of multiplexing.

The second effect is that the buffer capacity prepared for absorbing packet delay fluctuation in the receiving side device can be reduced. This is because the receiving-side device converts a packet that fluctuates in the arrival interval to a certain extent into an audio signal at a certain interval. Therefore, a buffer that temporarily accumulates the arriving packet and absorbs the fluctuation of the packet delay is needed, and the fluctuation width absorbed there is required. The smaller the number, the smaller the buffer capacity for storing the packets.
The reason for this effect is that a packet multiplexing control method for storing packets that cannot be multiplexed when a voice packet exceeds the bandwidth capacity in a buffer and switching the channel to be stored in the buffer irrespective of a change in a silent / voiced state. In the case of, the delay caused by the buffer accumulation by switching to the accumulation in the buffer at the time of multiplexing occurs as the packet delay fluctuation after the multiplexing. This is because such switching does not occur, so that packet delay fluctuation due to multiplexing is reduced.

Further, the third effect is that, when a packet is discarded exceeding the storage capacity of the packet buffer, means for notifying the sender of the packet discard is provided, so that the sender can communicate. In addition, it is possible to recognize a conversation that has not been made, and to reduce the number of voice packets staying in the packet buffer by interrupting the conversation, thereby achieving efficient use of the packet buffer.

That is, in the apparatus having no packet discard notification means according to the present invention, the occurrence of packet discard is recognized by the communication partner as a deterioration in voice quality or interruption of conversation, and the notification from the communication partner is notified. Since the sender cannot directly recognize the state of communication except in the case where packet discarding occurs frequently, the transmission state of the transmitted information cannot be sufficiently grasped. This is because these are improved. In addition, since the sender who has been notified of the packet discarding temporarily suspends the conversation, the accumulation of further voice packets in the packet buffer is stopped, and thereafter the transmission path traffic decreases, and the packet is accumulated in the packet buffer. This is because it is possible to newly accumulate voice packets of another channel in the empty packet buffer due to the transmitted packet being sent.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a voice packet multiplex transmission apparatus of the present invention.

FIG. 2 is a flowchart for explaining the operation of the voice packet multiplex transmission device according to one embodiment of the present invention.

FIG. 3 is a diagram for explaining packet multiplexing processing of the voice packet multiplex transmission apparatus according to one embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a conventional voice packet transmission device.

FIG. 5 is a block diagram showing a configuration of a conventional voice packet transmission device.

FIG. 6 is a diagram for explaining an example of the operation of a packet multiplexing unit often implemented in a conventional voice packet transmission device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Voice packet multiplex transmission apparatus 2 Transmission line 10 Line corresponding transmission unit 11 Voice encoding unit 12 Packetization unit 13 Voice / silence detection unit 20 Packet buffer unit 30 Packet multiplex control unit 40 ATM cell assembling unit 50 ATM cell decomposing unit 60 Line-related receiving unit 61 Depacketizing unit 62 Audio decoding unit 63 Silence reproduction unit 64 PB signal generation unit 65 Selection unit 201 Bit string conversion circuit 202 Bit position number addition circuit 203 Packet information generation circuit 204 Packetization circuit 205 Silence detection circuit 206 Control Circuit 210 Line corresponding unit 211 Input terminal 221 Input audio signal 223 Bit string conversion control signal 224 Bit position information 230 Multiplexing unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04L 13/00 307Z (72) Inventor Yuji Suzuki 1-4-2 Mita, Minato-ku, Tokyo NEC Communication Systems (72) Inventor Naoaki Tadokoro 4-4-2 Mita, Minato-ku, Tokyo NEC Communication Systems Co., Ltd. F-term (reference) 5K028 CC05 KK32 MM12 SS04 SS14 SS24 5K030 HA08 HA10 HB01 HB14 HC02 HC05 JA05 JA06 JT01 KA03 KA19 LA06 LB11 LC11 LE17 MA13 MB13 MB15 5K034 AA17 CC05 EE10 FF17 MM18 NN22

Claims (6)

[Claims] 1. A voice packet multiplex transmission apparatus for multiplexing and transmitting voice packets via a line, comprising: a voice / silence detection unit for determining a voice portion and a voiceless portion of voice information input from the line. Based on the determination result of the sound / silence detection unit, the sound part is encoded, and the silence part generates silence detection information only at the start of silence, and does not perform encoding in the silence state thereafter. A speech encoding unit, and adding a channel identification information and a speech / non-speech information to the encoded speech information and the silence detection information output from the speech encoding unit, and A packetizing unit for packetizing the first packet, and a packet buffer for storing the first packet in order to delay the start of multiplexing of the first packet output from the packetizing unit. A second packet assembler that multiplexes the first packet output from the packetizer or the packet buffer, multiplexes the first packet into a second packet, and outputs the multiplexed packet to a transmission path; The number of packets of the second packet multiplexed by the packet assembling unit and the first packet output from the packetizing unit from the channel of the first packet stored in the packet buffer unit. Voice packet multiplex transmission, comprising: a packet multiplexing control unit that controls accumulation in the packet buffer unit and controls multiplexing start of untransmitted packets of the first packet in the packet buffer unit. apparatus. 2. The packet multiplexing control unit, when storing the first packet output from the packetizing unit in the packet buffer unit, when the packet buffer unit has no free space, A PB signal generating unit that generates a push button (PB) signal for discarding the first packet and notifying the sender of the first packet of the discard of the first packet; Discarding the first packet by controlling a selection unit that selects voice information obtained by decoding a packet, reproduced silence information, and a PB signal for notifying discard of the first packet and outputs the signal to the line; 2. The voice packet multiplex transmission apparatus according to claim 1, wherein the voice packet multiplex transmission apparatus notifies the sender of the packet. 3. A line corresponding transmission unit corresponding to one line including the voice encoding unit, a sound / non-speech detection unit, and a packetization unit, and an AT which is the second packet from the transmission path.
AT that receives M cells and decomposes and outputs them to the receiver corresponding to each line
An M cell decomposing unit, a depacketizing unit of each of the line corresponding units for depacketizing the voice packet from the ATM cell decomposing unit, and receiving the voice digital signal from the depacketizing unit to detect the silent information. A silence reproducing unit for reproducing silence information, a voice decoding unit for reproducing voiced sound from the depacketizing unit and outputting voice information, and the first packet when there is no free space in the packet buffer unit. A PB signal generating unit for generating a PB signal for generating a notification of discarding, discarding the decoded voice information, the reproduced silence information, and the discarding of the first packet under the control of the packet multiplexing control unit. 3. The voice packet multiplex transmission apparatus according to claim 1, further comprising: a selection unit that selects a PB signal to be output and outputs the PB signal to the line. 4. The packet multiplexing control unit detects a voiced packet of the first packet or a silence of the first packet output from the packetizing unit or the packet buffer unit of the line corresponding transmission unit of each line. A determination is made as to whether or not a multiplexed channel is available for the packet, and for a channel already stored in the packet buffer unit, the latest first packet is stored at the end of the same channel in the packet buffer unit, 3. The voice packet multiplex transmission apparatus according to claim 1, wherein the first packet output order is not changed during multiplexing. 5. The packet multiplexing control unit, when the free space of the packet buffer unit is insufficient, sends a PB signal indicating the first packet discarding to the receiving side of the channel to the line corresponding receiving unit. 3. The voice packet multiplex transmission apparatus according to claim 1, wherein the first packet is discarded. 6. A voice packet multiplexing transmission method for multiplexing and transmitting voice packets via a line, wherein a transmitting unit for outputting voice signals from a plurality of lines comprises a sound part for voice information input from the line. Based on the result of the determination, encodes the sound portion and outputs it as audio information, and generates the silence detection information only at the start of silence for the silence portion. Outputs the silence detection information without performing encoding, and adds, to the speech information and the silence detection information, information for identifying a channel indicating the line and information for identifying speech / silence, and adds a packet to the packet. The packetization is performed, the packet is accumulated to delay the start of multiplexing of the packetized packet, and the packetization or the packet storing the packet is stored. Multiplexes the packets output from § unit outputs to the transmission path in the cell of the ATM cell, the packet multiplexing controller for controlling the transmission unit, the AT
From the number of packets to be multiplexed into M cells and the channel of the packets stored in the buffer, control is performed to store the packets to be packetized in the buffer. A voice packet multiplex transmission method characterized by controlling the start of multiplexing.