JPH0734558B2 - Voice packet communication system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to voice signal communication in a packet switching system.

[Conventional technology]

In communication using voice packets, the delay between the sending and receiving terminals greatly depends on the network configuration and status, and especially for packets sent through communication paths that pass through multiple links, intra-network delay is almost proportional to the number of links. Occurs.

FIG. 2 is a diagram showing a breakdown of total delays between terminals for transmitting and receiving packets in the packet switching system. Generally, the total delay between the transmitting and receiving terminals of a voice packet is a delay time for accumulating digital data output from an encoding device until it reaches a certain bit (packet length) as shown in FIG. "Delay", and the processing time spent on each transmission path and switch until the packet is received by the partner terminal, and the "queuing delay" that is the processing waiting time. Of these, "Packet creation delay"
Is determined only by the packet length, that is, the delay is proportional to the packet length. Regarding the "queuing delay", the queuing delay increases almost in proportion to the number of transit stages of the packet. The total delay increases or decreases depending on the virtual circuit.

Conventionally, fixed-length packets are used for all virtual circuits related to voice, and therefore the "packet creation delay" is constant, while the performance of transmission lines and exchanges included in the set virtual circuit. Since the "queuing delay" of increases and decreases according to the number of transits, the total delay depends on the number of transmission lines / switches included in the set virtual circuit.

[Problems to be solved by the invention]

In the method using fixed-length packets, the total delay between terminals increases or decreases depending on the length of the route in the set virtual circuit, and the quality of voice communication service is affected. Therefore, long-distance voice communication can uniformly receive only services of poor quality (large delay).

In addition, since the packet length is fixed, the limit of reduction of the delay time is limited by the fixed delay, that is, the packet creation delay, even in the communication that requires the real-time property.

Also, in a broadcast communication system in which some processing is performed on packets sent to multiple terminals at the same time when all response packets returned from these terminals arrive at the sending terminal, the waiting time for processing is queuing. The response performance depends on the packet passing through the virtual circuit with the longest delay because the response packet from the terminal with the long queuing delay is used instead of the response packet from the terminal with the shortest delay.

An object of the present invention is to solve the above problems and to set an appropriate packet length for each virtual circuit independently of the queuing delay related to the virtual circuit set between terminals, An object of the present invention is to provide a voice packet communication method capable of increasing or decreasing the total delay time.

[Means for solving problems]

The present invention relates to a voice packet communication method in which a virtual line is set and communication is performed every time a call is made, and the number of via switching nodes, the number of via transmission lines, and the via transmission line of a line set between transmitting and receiving terminals It is characterized in that a packet having a different data length is used for each call in accordance with at least one of the transmission rates.

[Action]

 The principle of the present invention will be described with reference to FIG.

In the figure, 104, 105, 106 are terminals, 107, 108, 109 are exchanges,
110 indicates a transmission path.

In the present invention, the number of transit transmission line stages in the call route (virtual circuit) between terminals set as shown in FIG.
The packet length is set according to at least one of the number of transit exchange stages and the transmission speed of the transit transmission line.

In FIG. 1, a packet 101 of a virtual circuit with many transit switching nodes going from the terminal 104 to the terminal 105.
The queuing delay of (data DEF) and 102 (data ABC) is packet 103 (data A) from the terminal 104 to the terminal 106 of the virtual circuit with few transit switching nodes.
Although it is larger than the queuing delay of (BCDEF), the present invention can reduce the packet creation delay by creating a packet shorter than the packet 103 for the packet 101 and the packet 102. As shown in the figure, the difference in total delay can be reduced by compensating for the difference in queuing delay with the difference in packet creation delay.

In addition, by shortening the packet length of the virtual circuit, which is likely to have a large number of via transmission line stages or the transmission speed of the via transmission line or the number of via switchboard stages, the queuing delay is increased. The response time from a large terminal can be shortened, and the overall response time can be shortened.

〔Example〕

 Next, examples of the present invention will be described.

FIG. 3 is a diagram showing communication control for determining the packet length at the time of call setup. In the figure, 301, 302, 303 are terminals, 306, 3
07 and 308 are exchanges, and 309 is a transmission line.

In FIG. 3, it is assumed that communication is performed from the terminal 301 to the terminals 302 and 303. In response to a call setup request from the terminal 301 to the terminal 302 and the terminal 303, after the call setup, a control packet 304 and a control packet 305 for notifying the setup completion are sent from the terminal 302 and the terminal 303 to the terminal 301, respectively.

FIG. 4 is a diagram showing the structure of this control packet. The control packet includes a field 402 indicating the number of exchange stages included in the set path, a logical channel number (LCN) 403 for identifying the set communication path, and a field 401 for other control information. Since the number of transmission lines has a relationship of the number of exchanges + 1, it is sufficient to have information on the number of exchanges.

In the network of FIG. 3, the field 402 of the control packet 304 contains information that the number of transit exchange stages between the terminal 301 and the terminal 302 is 3, and the field 402 of the control packet 305 includes information about the transit exchange between the terminal 301 and the terminal 303. Information that the number of stages is 2 is included.

FIG. 5 is a diagram showing a packet creation unit of the transmission terminal. In the figure, 501 is an A / D exchange circuit, 503 is a data buffer, 504 is a packet length memory, 505 is a header addition circuit, 506 is a packet assembly circuit, 507 is a network, and 508 is a packet buffer.

Digital data 502 sent from the A / D conversion circuit 501
Are stored in the data buffer 503. The packet length determined for each LCN 403 based on the information in the respective fields 402 of the control packet 304 and the control packet 305 at the time of call setup is recorded in advance in the packet length memory 504 for each LCN 403. If the digital data 502 accumulated in the data buffer 503 has a length that matches the packet length recorded in the packet length memory 504 for each LCN, the header adding circuit
The header created by 505 and the packet assembling circuit 506 are combined to create a packet, which is sent to the network 507 via the packet buffer 508.

In this embodiment, only the number of exchange stages is used as the control parameter, but a configuration in which the speed of the transmission line is added to the format is also possible.

〔The invention's effect〕

According to the present invention, for the queuing delay related to the virtual circuit set between the terminals, independently of it,
The total delay time can be increased or decreased by setting an appropriate packet length for each virtual circuit.

Therefore, by setting an appropriate packet length, it is possible to reduce the influence of the difference in queuing delay caused by the voice packet transmitted from the transmitting terminal to the receiving terminal passing through a different virtual circuit for each call. it can.

In addition, shortening the packet length generally leads to an increase in transmission cost. However, even if the user provides short-distance long-distance communication due to the corresponding cost burden, or conversely, the real-time property is low and the total delay time is large. By increasing the packet length for packets in a virtual circuit between good terminals, low-cost communication can be provided.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the principle of the present invention, FIG. 2 is a diagram showing a breakdown of total delays between terminals of packet transmission / reception in a packet switching system, and FIG. 3 is an embodiment of the present invention. FIG. 4 is a diagram showing communication control for determining a packet length at call setup in FIG. 4, FIG. 4 is a diagram showing a configuration of a control packet in the embodiment of the present invention, and FIG. 5 is a packet of a transmitting terminal in the embodiment of the present invention. It is a figure which shows a creation part. 101,102,103 …… Packet 104,105,106,301,302,303 …… Terminal 107,108,109,306,307,308 …… Switch 110,309 …… Transmission path 304,305 …… Control packet 501 …… A / D conversion circuit 503 …… Data buffer 504 …… Packet length memory 507 …… Network 508 …… Packet buffer

Claims (1)

[Claims] 1. A voice packet communication system for setting a virtual line every time a call is made to perform communication, and the number of via switching nodes, via transmission lines, and via transmission of a line set between transmitting and receiving terminals. A voice packet communication system characterized in that a packet having a different data length is used for each call according to at least one of the transmission rates of the routes.