JP2000196662A - Packet multiple transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable stable transmission by recovering the delay when an untransmitted packet exists and limiting a maximum transmission speed. SOLUTION: This packet multiple transmitter has a timer 103 which generates a transmission trigger in every minimum packet interval and a transmission time holding part 106 which holds time to transmit the next packet. When the current time passes the time to transmit the packet and also when a transmission trigger exists, the packet is transmitted. Thus, the delay of packet transmission time is made minimum and also, the minute packet interval is maintained all the time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packet multiplex transmission apparatus for digitizing continuous information such as voice and video at a certain speed, packetizing the same, multiplexing it with other information, and transmitting the multiplexed information to a remote place via a network. It is about.

[0002]

2. Description of the Related Art When transmitting packets of time-continuous information, such as video and audio, at a certain transmission rate in real time, a method of sending out packets at fixed time intervals is often used. In this method, since the amount of transmission information is constant, the resources of the network can be used without waste, and the receiving side can receive at a predetermined speed.
It is easy to process the received information in real time. When transmitting continuous information of a plurality of channels in such a packet transmitting apparatus, a general method is to generate packets at fixed time intervals for each channel and time-division multiplex them.

FIG. 1 shows an example of a conventional packet multiplex transmission apparatus based on the above concept. In this example, continuous transmission data 2001A, 2001B, 2001C of three channels
Packets at time intervals 2002A and 2002, respectively.
B, 2002C, multiplexed and output. Hereinafter, the operation of this example will be described.

[0004] A portion for controlling packet transmission is provided for each transmission channel. The packet transmission unit 201A of channel 1 controls the transmission timing of the transmission data 2001A of channel 1. The transmission data packet 2001A is temporarily stored in the transmission queue 203A and waits for a transmission time. The packet transmission unit of each channel transmits a reference clock 1 which is a pulse signal serving as a time reference from the reference clock generation unit 111.
003 is provided. The timer 202A counts the reference clock 1003, clears itself each time it reaches the time interval information 2002A, and simultaneously sends a transmission trigger to the transmission control unit 204A. The transmission control unit 204A extracts a packet from the transmission queue 203A every time a transmission trigger is received, and outputs the packet to the multiplexer 113 as a packet output 2002A. With this procedure, packets are sent to the multiplexer at regular intervals according to the transmission time interval 2002A.

Similarly, packet transmission section 201B controls the output time of transmission data packet 2001B of channel 2 according to transmission time interval 2002B,
1C controls the output time of the transmission data packet 2001C of channel 3 according to the transmission time interval 2002C. In the multiplexer 113, the arriving packets 2003A, 2003
B and 2003C are transmitted to the transmission path as transmission packets 1013 in the order of arrival.

According to the above procedure, the packets of channel 1, channel 2, and channel 3 are multiplexed and output according to each time interval.

[0007]

In the above-described packet multiplex transmitting apparatus, various problems may occur if the operating conditions are not ideal. A problem associated with the present invention is that if a packet on a channel cannot be transmitted for any reason, it may adversely affect the transmission timing of subsequent transmitted packets. The reasons why packets cannot be transmitted are as follows.

(1) A case where the transmission path is temporarily saturated and a packet to be transmitted at that moment cannot be output. (2) When the packet cannot be transmitted due to collision with packet transmission of another channel. (3) When no packet is prepared in the transmission queue even at the time to transmit.

[0009] The result is the same even if the cause is different.
Normally, when a packet to be transmitted is not output at the timing to be transmitted, the packet remains in the transmission queue and waits for the next transmission timing. As a result, all subsequent packets are output with a delay of one packet interval. This means that necessary data does not arrive at the receiving side when required, and in some cases, transmission failure occurs.

[0010] On the other hand, transmission devices provided with a mechanism for preventing this have conventionally existed. This is to accumulate the number of unsuccessfully transmitted packets, and to transmit them as soon as possible once transmission is possible. In this case, the transmission delay is temporary, and the reception failure on the receiving side can be reduced. However, this case also has the following problem.

When transmission becomes possible, transmission is attempted as soon as possible. If there are many packets that could not be transmitted, the packets will be transmitted at a speed that is full of the permissible speed of the network for a while. . As a result, if there is a repeater or the like in the transmission path, the transmission speed may exceed the permissible speed, resulting in transmission failure. In addition, the receiving side may not be able to completely receive the data, which may result in transmission failure.

An object of the present invention is to provide a packet multiplexing transmission apparatus which realizes stable transmission by recovering the delay of untransmitted packets when there is, and limiting the maximum transmission rate.

[0013]

In order to achieve the above object, a packet multiplex transmitting apparatus according to the present invention includes a timer section for generating a trigger indicating that transmission is possible according to a minimum transmission interval, and a timing for transmitting a next packet. A transmission time holding unit that holds the current time, a comparing unit that compares the current time with the transmission time, and a transmission control unit that transmits a packet when the current time exceeds the transmission time and a transmittable trigger is input. Have.

[0014]

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

FIG. 2 shows the configuration of a packet multiplex transmission apparatus according to one embodiment of the present invention. This configuration example shows a case where a packet of continuous data of three channels is transmitted. As in the conventional example of FIG. 1, transmission data 1010 of channel 1
The transmission process of the packet A is performed by the packet transmission unit 101A for channel 1 and the transmission process of the transmission data 1010B of channel 2 is performed by the packet transmission unit 101B for channel 2 and channel 3.
The transmission process of the transmission data 1010C is performed by the packet transmission unit 101C for channel 3. If the number of channels is N, N packet transmission units may be connected.
The packet outputs 1012A, 1012B, and 1012C from the packet transmission units 101A, 101B, and 101C are time-division multiplexed in the arrival order by the
13 is transmitted to the transmission path.

The reference clock generator 111 generates a reference clock 1003, which is a pulse signal serving as a reference for controlling the transmission time of the entire device,
1B, 101C and the reference time generator 112. In the reference time generation unit 112, the reference clock 1003
The current time 1004 is generated based on the
01A, 101B and 101C.

Next, the channel 1 packet transmission section 101A
Will be described. Transmission data 10 of channel 1
10A is stored in the temporary transmission data queue 109 and waits for transmission. Data 1001A used for setting the minimum transmission interval of the packet is converted into a minimum transmission interval (Tmin) 1002 in the minimum transmission interval holding unit 102 and stored. The timer 103 counts the reference clock 1003 for the minimum transmission interval 1002, and generates a transmittable pulse 1005 once at the minimum transmission interval. On the other hand, data 1006 used for setting an average packet transmission interval
A is a transmission interval (Tav) 100 in the transmission interval holding unit 104.
7 and stored. The transmission time holding unit 106 always holds the transmission time 1008 of the next packet. Each time one packet is transmitted, the transmission interval 1007 and the transmission time 1008 are added by the adder 105, that is, the value of the next packet. Updated at transmission time. Transmission time 100
8 is compared with the current time 1004 by the comparator 107. If both the condition that the current time 1004 has passed the transmission time 1008 and the condition that the transmittable pulse 1005 is positive are satisfied, the logical product 108 generates a transmission trigger 1009. Upon receiving the transmission trigger 1009, the transmission control unit 110 extracts the packet 1011 to be transmitted from the transmission data queue 109 and outputs the packet 1010.
Output as 12A. If the transmission is successful, the transmission control unit 110 sets the update trigger 1014 to the transmission time holding unit 1
06, and updates the transmission time 1008 to the next packet transmission time.

The operation of the embodiment of FIG. 2 will be described more specifically with reference to the time charts of FIGS. 3, 4, and 5. FIG. 3 is a time chart in the case where no compensation is made even when there is a period during which transmission is not possible. FIG. 4 is a time chart in a case where measures are taken for a time during which transmission is impossible, but the maximum transmission speed is not limited. FIG. 5 is a time chart in a case where the transmission disabled time is compensated for and the maximum transmission speed is limited by the configuration of FIG. 3, 4, and 5, the vertical axis represents traffic volume, and the horizontal axis represents time transition. Packet transmission 301 is represented by a rectangle as shown. In these examples, the state of transmission of the transmission packet 301 at the average packet interval 302 and the subsequent packet transmission when the transmission impossible period 303 occurs are schematically illustrated. In the case of FIG. 3, since there is no compensation even if there is a period during which transmission is not possible, each transmission packet is transmitted with a delay corresponding to the period during which transmission is impossible from the time when transmission should be originally performed, and the delay is not recovered. .
In the case of FIG. 4, if there is a transmission disabled period, the number of packets that failed to transmit is counted, and the failed packet is being transmitted at the maximum speed immediately after transmission becomes possible. In this method, the delay of packet transmission can be recovered immediately, but packets are concentrated and transmitted immediately after the transmission disabled period, and if the receiving side or the relay device in the transmission path etc. do not have sufficient speed May cause a transmission failure due to a delay in processing. FIG. 5 shows the operation of the packet multiplex transmission apparatus of the present invention. In the packet multiplexing apparatus of the present invention, the average packet interval (Ta
v), but when the transmission disable period 303 occurs, the transmission time is delayed, and the minimum packet interval (Tmin) 304 is maintained until the delay is eliminated.
Packets are transmitted at intervals of. As a result, the packet transmission delay is quickly eliminated while maintaining the maximum transmission rate limit.

FIG. 6 shows a packet multiplex transmitting apparatus according to another embodiment of the present invention. A feature of this embodiment is that, in addition to data transmitted at a constant speed, data for which transmission time does not need to be guaranteed can be multiplexed and transmitted. In this case as well, as in the example of FIG. 2, the transmission delay of data to be transmitted at a constant speed is quickly eliminated even if there is a temporary transmission impossible time while observing the limit of the maximum transmission speed. The transmission processing of the packet of the other data (data for which the transmission time does not need to be guaranteed) 4002 like the transmission data 4001 of the constant speed of the channel 1 is performed by the packet transmission unit 40 for the channel 1.
1A, transmission data of channel 2 is transmitted by a packet transmission unit 401B for channel 2, and transmission processing of transmission data of channel 3 is performed by a packet transmission unit 401C for channel 3. Each of the packet transmission units 401A, 401B, and 401C is similar to the example of FIG.
Output 4009A, 4009B, 4009 from
C is time-division multiplexed by the multiplexer 113 in the order of arrival and transmitted to the transmission line as a transmission packet 1013.

The reference clock generator 111 generates a reference clock 1003, which is a pulse signal serving as a reference for controlling the transmission time of the entire apparatus, and transmits the packet to the packet transmitters 401A and 401A.
1B, 401C and the reference time generator 112. In the reference time generation unit 112, the reference clock 1003
The current time 1004 is generated based on the
01A, 401B, and 401C.

The internal operation of the channel 1 packet transmitting section 401A will be described. Transmission data 4001 at a constant speed of channel 1 is stored in the temporary transmission data queue 403 and waits for transmission. The other transmission data 4002 of channel 1 is stored in the transmission data queue 404 and waits for transmission. Data 1001A used for setting the minimum transmission interval of the packet is converted into a minimum transmission interval (Tmin) 1002 in the minimum transmission interval holding unit 102 and stored. The timer counts the reference clock 1003 for the interval of the minimum transmission interval 1002, and generates a transmission trigger 4003 once at the minimum transmission interval. On the other hand, the data 1006A used for setting the average packet transmission interval is converted into a transmission interval (Tav) 1007 by the transmission interval holding unit 104 and held. The transmission time holding unit 106 always holds the transmission time 1008 of the next packet. Each time one packet is transmitted, the transmission interval 1007 and the transmission time 1008 are added by the adder 105, that is, the value of the next packet. Updated at transmission time. The transmission time 1008 is set to the comparator 10
7 and is compared with the current time 1004.
When the transmission time 4 has passed the transmission time 1008, the transmission request signal 4005 is output. Upon receiving the transmission trigger 4003, the transmission control unit 406 reads a packet from either the transmission data queue 403 or the transmission data queue 404, and outputs a packet output 4009A. At this time, the selector 405 determines which queue to read from. When the transmission trigger 4003 occurs, if the transmission request signal 4005 is positive, that is, the transmission time of the constant-speed transmission data has passed, it is read from the transmission data queue 403, and if the transmission request signal 4005 is false, that is, the constant-speed transmission data If the transmission time has not passed, the data is read from the transmission data queue 404. Transmission request signal 400
If 5 is false and the transmission data queue 404 is empty, no packet transmission is performed. When the transmission of the data packet from the transmission queue 403 is successful, the transmission control unit sends an update trigger 4004 to the transmission time holding unit 106, and updates the transmission time 1008 to the next packet transmission time.

As a result, in the example of FIG. 6, data which does not need to guarantee the transmission time at a constant speed using the difference between the minimum packet interval and the average packet interval while having the features of the example of FIG. Can be executed without obstructing the transmission of the data and maintaining the maximum transmission speed.

FIG. 7 shows a specific channel transmission unit in which the transmission time can be set for each transmission packet by extending the example of FIG. In this example, the scheduled transmission time for each packet can be specified, so that the packet can be transmitted not only at a constant speed but also at any timing.

In this example, the transmission data packet 101
0A is stored in the transmission data queue, and the transmission time 7001 of each packet is accumulated in the transmission time queue 701. As in the case of FIG. 2, the data 1001A used for setting the minimum transmission interval of the packet is the minimum transmission interval holding unit 1
02, it is converted to a minimum transmission interval (Tmin) 1002 and stored. In the timer 103, the minimum transmission interval is 10
The reference clock 1003 is counted for an interval of 02, and a transmittable pulse 1005 is generated once at the minimum transmission interval.
The transmission time setting unit 702 reads the transmission time 1008 of the next packet to be transmitted from the transmission time queue 701 one by one,
Send to comparison section 107. The comparing unit compares the current time 1004 with the transmission time 1008 to determine whether the current time 1004 has passed the transmission time 1008. If both the condition that the current time 1004 has passed the transmission time 1008 and the condition that the transmittable pulse 1005 is positive are satisfied, the logical product 108 sets the transmission trigger 1
009 is generated. The transmission control unit 110 transmits the transmission trigger 10
When receiving the packet 09, one packet is read from the transmission data queue 109 and output as an output packet 1012 </ b> A. When output is successful, an update trigger 1014 is issued to the transmission time setting unit 1014. When receiving the update trigger 1014, the transmission time setting unit 1014 reads the transmission time of the next packet from the transmission time queue 701 and sends it to the comparison unit 107.

[0025]

According to the present invention, since the time at which a packet is to be transmitted is always held for each transmission channel, the delay of the packet transmission time of each channel is automatically adjusted so as to always be minimized. Is done. For this reason, the average transmission speed is kept constant, and the delay of the arrival time of the packet does not accumulate, so that the possibility of hindering the processing on the receiving side is reduced.

On the other hand, since packets are transmitted at intervals longer than the interval set at the minimum transmission interval, the normal maximum transmission rate is not exceeded in any case. For this reason, in the relay device and the receiving device in the transmission path, the probability that a transmission failure occurs even temporarily exceeding the transmission processing capability is reduced.

Also, by utilizing the difference between the maximum transmission speed and the average transmission speed, it is possible to insert a packet that does not need to guarantee the transmission time into a gap between packets to be transmitted while maintaining the average transmission speed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a conventional packet multiplex transmission device.

FIG. 2 is a configuration diagram of a packet multiplex transmission apparatus according to one embodiment of the present invention.

FIG. 3 is a time chart in a case where a conventional packet multiplex transmission apparatus does not perform any compensation for a period during which transmission is impossible.

FIG. 4 is a diagram showing a time chart in a case where a conventional packet multiplex transmission device takes measures against a time during which transmission is impossible, but does not limit the maximum transmission speed.

FIG. 5 is a diagram showing a time chart in a case where the packet multiplex transmission apparatus according to one embodiment of the present invention compensates for a transmission disabled time and further limits a maximum transmission speed.

FIG. 6 is a configuration diagram of a packet multiplex transmitting apparatus according to another embodiment of the present invention.

FIG. 7 is a block diagram of a packet multiplex transmitting apparatus according to still another embodiment of the present invention, which is thicker;

[Explanation of symbols]

101A: Packet transmission unit for channel 1, 101B: Packet transmission unit for channel 2, 101C: Packet transmission unit for channel 3, 102 ... Minimum transmission interval holding unit, 103 ...
Interval timer, 104: transmission interval holding unit, 105
... adder, 106 ... transmission time holding unit, 107 ... comparator,
108: logical product, 109: transmission data queue, 110
... a transmission control unit, 111 ... a reference clock generation unit. 112 ...
Reference time generation unit, 113: multiplexer, 201A: packet transmission unit for channel 1, 201B: packet transmission unit for channel 2, 201C: packet transmission unit for channel 3, 20
2A: Interval timer of channel 1, 202B: Interval timer of channel 2, 202C: Channel 3
, An interval timer of 203A... Transmission queue of channel 1, 203B... A transmission queue of channel 2, 203C.
Channel 3 transmission queue, 204A ... channel 1 transmission controller, 204B ... channel 2 transmission controller, 204C
... Transmission control unit of channel 3 301 transmission packets 3
02: average transmission interval, 303: transmission disabled period, 304:
Minimum transmission interval, 401A: packet transmission unit for channel 1, 401B ... packet transmission unit for channel 2, 401C
.., Channel 3 packet transmission unit, 403, constant speed data queue, 404, other data queue, 405
Selector, 406: transmission control unit, 4008: selected transmission packet, 701: transmission time queue, 702: transmission time setting unit, 7001: transmission time for each packet.

Claims (6)

[Claims] 1. A packet multiplexing apparatus for packetizing and transmitting temporally continuous digital information, comprising means for calculating a time at which each packet is to be transmitted, and comparing a current time with a time at which the packet is to be transmitted. Means for generating, a signal indicating that transmission is possible at every minimum packet transmission time interval, and a current time when a signal indicating that transmission is possible is received by the signal generation means. Means for outputting a packet to a transmission path when the time to transmit the packet has passed. 2. Packet multiplex transmission in which time-continuous digital information whose transmission time delay time must be guaranteed and digital information whose delay time need not be guaranteed are packetized and time-division multiplexed and transmitted. An apparatus for calculating a time at which each packet should be transmitted for digital information for which a delay time needs to be guaranteed; a means for comparing a current time with a time at which a packet should be transmitted; and a minimum packet transmission time. Means for generating a signal indicating that transmission is possible at each interval, and a delay time when the current time has passed the time to transmit the packet when the signal indicating that transmission is possible is received Output the corresponding packet of the information that needs to be guaranteed to the transmission path, and if the current time is not after the time to transmit the packet, the delay time If status packet without information required transmission waiting certifying, packet multiplexing transmission apparatus and means for transmitting it. 3. A packet multiplexing apparatus for packetizing and transmitting digital information which is continuous in time, means for storing a time at which each packet should be transmitted in association with each packet, and transmitting a current time and a packet. Means for comparing with a time to be transmitted, means for generating a signal indicating that transmission is possible at every minimum packet transmission time interval, and upon receiving the signal indicating that transmission is possible, the current time indicates that the packet is Means for outputting a packet to a transmission path when a time to be transmitted has passed. 4. A packet multiplexing transmission apparatus for packetizing and transmitting time-continuous digital information of a plurality of channels, and time-division multiplexes transmission packets of each channel onto a transmission path shared by the channels. Means for transmitting, means for calculating the time to transmit each packet for each channel, means for comparing the current time for each channel with the time to transmit the packet, and the minimum packet transmission time for each channel Means for generating a signal indicating that transmission is possible at each interval, and when receiving the signal indicating that transmission is possible, if the current time is past the time to transmit the packet, Means for sending a packet to be transmitted to said time division multiplexing means. 5. Digital information for which it is necessary to guarantee a time delay of transmission time continuously over a plurality of channels,
What is claimed is: 1. A packet multiplexing transmission apparatus for packetizing digital information that does not need to guarantee a delay time associated with each channel and transmitting the digital information in a time-division multiplexed manner, wherein a transmission packet for each channel is shared between the channels. Means for time-division multiplexing and transmission, means for calculating the time at which each packet should be transmitted for digital information for which a delay time needs to be guaranteed for each channel, and the current time for each channel. Means for comparing with the time to transmit the packet, means for generating a signal indicating that transmission is possible at each minimum packet transmission time interval, and a signal indicating that transmission is possible for each channel. At this point, if the current time is past the time at which the packet should be sent, the corresponding packet of information for which a delay time needs to be guaranteed is If the current time is not after the time at which the packet should be transmitted and the packet of information that does not need to guarantee a delay time is in a transmission waiting state, the packet is output to the time division multiplex transmission. Means for sending to the means. 6. A packet multiplexing transmission apparatus for packetizing and transmitting time-continuous digital information of a plurality of channels, and time-division multiplexes transmission packets of each channel onto a transmission path shared by the channels. Means for transmitting, means for storing the time to transmit each packet for each channel in association with each packet, means for comparing the current time for each channel with the time to transmit the packet, Means for generating a signal indicating that transmission is possible at every minimum packet transmission time interval of, and upon receiving the signal indicating that transmission is possible, the current time is past the time at which the packet should be transmitted. Means for transmitting a corresponding packet to said time-division multiplexing means.