JPH05207063A - Packetized voice delay control system - Google Patents

Abstract

PURPOSE:To shorten the total delay time of a packetized voice by controlling the sending timing of the packetized voice to a vocoder by the display value of the delay time of the packetized voice in a control data field arriving from a switching machine. CONSTITUTION:Packet switching machines 103, 105 calculate a time passing the switching machine from difference between time (tin) when the packetized voice arrives and the transmission time (tout) of the packetized voice to another station or PAD, and finds difference (td) between the time value and reference in-switching machine delay time (ts) measured and stored in advance, and sets it on the control data field of the header of the packetized voice. A PAD 108 receiving the packetized voice checks the value of the delay time display (td) set on the control data field of the packetized voice, and deletes the packetized voice with delay time over a constant value, and handles it as silence.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packet switching system, and more particularly to a voice packet delay control system.

[0002]

2. Description of the Related Art Conventionally, in this type of voice packet communication system, a voice packet assembling / disassembling apparatus (hereinafter referred to as P
Voice packets generated in a constant cycle by AD) arrive at the PAD on the receiving side with delay due to various causes in the packet switch. This arrival time does not have a fixed cycle due to fluctuations in the network delay time. Therefore, in the conventional voice packet communication method, as shown in FIG. 3, a voice packet communication call (virtual call) is made at the receiving side PAD.
After the setting, the measurement of the voice packet transmission timing is started so that the time interval becomes equal to the voice packet generation cycle. When the voice packet first arrives from the transmitting terminal side, the voice packet is temporarily held, and when the voice packet transmission timing is reached, the held voice packet is sent to the receiving terminal. If the voice packet does not arrive after the voice packet is transmitted until the next voice packet transmission timing, it is determined that silence has occurred on the transmitting side, and the vocoder is instructed to transmit the silence.

[0003]

In the conventional voice packet communication system described above, the voice packet is always held after the voice packet is sent to the receiving terminal. Therefore, in the worst case, the sending timing, that is, the voice packet generation period There is a drawback in that a delay of the same amount of time occurs, which hinders the call.

An object of the present invention is to provide a voice packet delay control system which shortens the total delay time of voice packets and improves the call quality.

[0005]

According to the voice packet delay control system of the present invention, a packet switch having a voice packet communication function has a function of storing a standard intra-switch delay time and a relay line during communication by voice packets. Alternatively, the time elapsed from the reception of the voice packet from the voice packet assembling / disassembling device to the transmission of the voice packet to another trunk line or the voice packet assembling / disassembling device is measured and stored in the standard exchange. A function of calculating the difference from the delay time, integrating the difference time into a control data field which is a part of the control information field of the voice packet, and displaying it, and a delay in the control data field of the voice packet arriving from the packet switch. The voice packet set for controlling the timing of sending the voice packet to the vocoder by the value of the time display / And a cracking unit.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a packet switching network for explaining voice packet delay time measurement according to one embodiment of the present invention. Telephones 101 and 107 convert analog voice signals into digital signals and digital signals into analog voice signals. Vocoders 102 and 106, PADs 108 and 109 for assembling and disassembling voice packets, packet switches 103 and 105 having a voice packet communication function, and a trunk line 104 connecting the packet switches. FIG. 2 is a time chart showing the transmission timing of a voice packet in an embodiment of the voice packet delay control system of the present invention.

First, a delay time measuring method according to the present invention will be described with reference to FIG. The vocoder 102 receives the analog voice signal from the telephone 101, converts it into a digital voice signal, and the PAD 108 generates a voice packet from this digital voice signal, whereby a voice packet is generated. When voice of a certain level or higher is continuously generated, this voice packet is periodically cycled at a timing that is a period until the amount of voice data necessary for the PAD 108 to generate the voice packet is accumulated. Occur.

When the volume of voice falls below a certain level, the PAD 108 determines that no voice is generated, and does not generate a voice packet in the cycle of the transmission timing. When the original voice is reproduced from the voice packet, the PAD 109 receives the voice packet and sequentially outputs the vocoder 10 at the same timing as the voice packet is generated.
According to 6, if the analog voice signal is not converted and sent to the telephone set 107, the continuity as a sound cannot be maintained like the original voice. Similarly, in the case of silence, because there is no voice packet at the same timing as the timing of silence generation,
The PAD 109 instructs the vocoder 106 to output silence during the cycle.

Therefore, the PAD1 which produces the voice packet
08 sequentially sends out the voice packets to the packet switch 103 in accordance with the voice packet generation timing.
The packet switch 103 promptly transmits the voice packet to the packet switch 105 via the trunk line 104, and the packet switch 105 sends P packets each time the voice packet arrives.
Promptly send to AD109.

The delay time that occurs when a voice packet is transferred in this way is the delay (tc1) that occurs in the process of generating the voice packet and the transmission delay (tc) on the trunk line.
2), a delay (tc3) generated in the process of decoding a voice packet, and a delay (ts) generated in the packet switch.
1, ts2). tc1 to tc3 are vocoders 10
2, 106, PADs 108, 109 are fixed values that are determined by conditions such as processing capacity and line speed. However, the delays ts1 and ts2 in the packet switch depend on the load state of the switch, so that the total delay time fluctuates. It will be.

In the voice packet delay control system of the present invention,
Time ti when the voice packet arrives at the packet switch
n and voice packet transmission time to other station or PAD to
The time elapsed for passing through the inside of the exchange is calculated from the difference of ut, and the difference between the value and the standard internal delay time ts measured and stored in advance is obtained. This difference value td is set in the control data field of the header of the voice packet as a delay time display. At this time, if td has already been set in the exchange at the preceding stage, the value is integrated and set to that value.

Next, a method of controlling the transmission timing of the voice packet by the delay time display td set in the control data field will be described with reference to FIG. Upon receiving the voice packet from the packet switch side, the PAD 109 checks the value of the delay time display td set in the control data field of the voice packet, discards the voice packet having the delay time of a certain value or more, and treats it as silence. Therefore, the number of voice packets transmitted to the vocoder 106 (see FIG. 1) on the receiving side does not always match the number of packets on the transmitting side as shown in FIG. The holding time (that is, the voice packet generation timing) is not held, and it can be sent by holding for a shorter time. Therefore, the worst value of the total delay time of voice packets can be shortened.

[0013]

As described above, according to the present invention, the PAD
In (1), the worst value of the total delay time of voice packets is shortened by controlling the transmission timing of the voice packet to the vocoder by the value of the delay time display value in the control data field of the voice packet arriving from the packet switch. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a block diagram of a packet switching network for explaining a voice packet delay time measurement according to an embodiment of the present invention.

FIG. 2 is a time chart showing a voice packet transmission timing in FIG.

FIG. 3 is a time chart showing the transmission timing of a voice packet in the conventional voice packet communication system.

[Explanation of symbols]

101, 107 Telephone 102, 106 Vocoder 103, 105 Packet switch 104 having voice packet communication function 104 Relay line 108, 109 Voice packet assembling / disassembling device (PA)
D)

Claims (1)

[Claims] 1. A packet switch having a voice packet communication function, which has a function of storing a standard intra-switch delay time, and a voice packet received from a relay line or a voice packet assembling / disassembling device during communication by voice packet. From the time until the voice packet is transmitted to another trunk line or a voice packet assembling / disassembling device, the difference from the stored standard switching delay time is calculated, and the difference time is calculated as the voice packet. Of the control data field, which is a part of the control information field, and the display timing of the voice packet arriving from the packet switch according to the delay time display value in the control data field. And a voice packet assembling / disassembling device for controlling the voice packet delaying. Deferred control method.