JPH05336152A - Multi-medium multiplex system - Google Patents

Abstract

PURPOSE:To implement multiplexing by taking both a delay time and an abort rate into account at all times. CONSTITUTION:A delay priority revision threshold level DL1 is set to a waiting cell number of each port in the case of polling control. When a waiting cell number WC1 of any port exceeds the threshold level, the number of cells to be set when the port is once selected is increased. Thus, the priority of the port in the polling control is increased. On the other hand, an abort priority revision threshold level LL1 is set to a delay time of each port in the case of a queue length monitor control. When a delay time DE1 of any port exceeds the threshold level, a queue length monitoring offset QO1' of the port is decreased. Thus, the priority of the port for the queue length monitor control is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multimedia multiplexing system which efficiently multiplexes media having different required qualities while satisfying the required qualities of the respective media.

[0002]

2. Description of the Related Art In ATM (Asynchronous Transfer Mode), which has been actively studied as a next-generation communication technique, information is divided into fixed-length cells for transmission. Therefore, media with different required qualities such as video, audio, and data can be handled in a unified manner. On the other hand, when these multimedia information is multiplexed and transmitted by ATM, the communication quality (transmission delay, cell loss rate, etc.) varies due to temporal changes in traffic. Therefore, keep the utilization efficiency of the network high,
And it is necessary to devise to maintain communication quality.

Conventionally, as a multimedia multiplexing method in an ATM network, a control method has been proposed which combines polling control advantageous for delay time and queue length monitoring control advantageous for cell discard (Kajiyama et al. "Multimedia multiplexing method in ATM network", IEICE Transactions BI Vol.J74-BI No.5 pp.399-407 1991 5
Month). The multiplexing algorithm will be described with reference to FIG.

As shown in FIG. 2, cells to be transmitted are stored in separate queues 21, 22 and 23 for each quality class. Although the number of quality classes is set to 3 in this conventional example, this number can be arbitrarily set depending on the media to be multiplexed. Each buffer length is B and is constant. The queue 21 of port 1 stores cells of a class that is strict about discarding and not strict about delay. The queue 22 of port 2 stores cells of a class that is moderately strict regarding discard and delay. Port 3 queue 23
Stores cells of a class that is sensitive to delay and less severe to discard. Selector 24 is the most difficult port to discard,
That is, the number of waiting cells in the queue 21 of port 1 is monitored, and the polling control and the queue length monitoring control are switched according to the value.

In this method, a threshold Th is set to the number of waiting cells of the port that is most strict in discarding, that is, port 1. When the number of waiting cells in the queue 21 is Th or less, polling control is performed to select each port in order at a constant cycle. The polling control here is skip polling that skips to the next port when there is no cell at the port. Each port has a polling offset value PO _i (i = 1,2,3). If the number of waiting cells is less than or equal to PO _i , it is considered that no cells are stored in that port and is not selected. If the number of waiting cells at all ports is less than or equal to PO _i, normal interlace polling without offset value is performed. By setting PO _i to be high for ports with low delay requirements, ports with low delay requirements are not selected until cells have accumulated to some extent, so that cells in a delay strict class can be preferentially transmitted.

On the other hand, when the number of waiting cells in the queue 21 exceeds the threshold value Th, the queue length monitoring control for selecting the port with the maximum number of waiting cells is performed. Again, the queue length monitoring offset value QO _i (i = 1,2,3) is set for each port. Select the port with the maximum value of the number of waiting cells minus QO _i . Q
By setting O _i low for a port that is strict in discarding, cells in a class that is strict in discarding can be preferentially transmitted. In either case, the selected port sends out cells one by one.

[0007]

By the way, according to the above-described multiplexing method, whether polling control or queue length monitoring control is performed is determined by the number of waiting cells of the port that is most severe to discard. Therefore, even if the number of waiting cells of another port that is severe to discard (for example, port 2 in the conventional example) increases in a burst manner, polling control is performed if the number of waiting cells of the port for which the threshold value Th is set is Th or less. Then, there is a problem that the quality of the ports other than the Th setting port, which are severe to discard, deteriorates.

On the other hand, there is a similar problem even when the queue length monitoring control is performed. That is, even if the delay time of the port with severe delay exceeds the allowable value, the queue length monitoring control is performed as long as the number of waiting cells of the Th setting port does not become Th or less. Therefore, there is a problem that the quality of the class that is strict in delay is deteriorated.

It is an object of the present invention to solve the above problems and to provide a multimedia multiplexing system which efficiently multiplexes cells of a plurality of media while satisfying the required quality.

[0010]

In order to solve the above problems, the present invention sets a delay priority update threshold for the number of waiting cells for all ports and performs polling control. When the number of waiting cells of any port exceeds the set delay priority update threshold, increase the number of cells to send when that port is selected once,
When the number of waiting cells becomes equal to or less than the delay priority update threshold, the number of cells to be transmitted when the port is once selected is returned to the original value.

On the other hand, the discard priority update thresholds are set for the delay times for all the ports, and the delay time is discarded for any one of the ports when the queue length monitoring control is performed. When the delay time exceeds, the queue length monitoring offset value of the port is decreased, and when the delay time becomes equal to or less than the discard priority update threshold, the queue length monitoring offset value of the port is returned to the original value.

[0012]

According to the present invention, even when delay priority control such as polling control is performed, if the number of waiting cells of a discard priority port increases, the number of cells to send when the port is once selected. To increase. As a result, the priority of that port in polling control can be increased. Even when discard priority control such as queue length monitoring control is performed, if the delay time of a delay priority port increases, the queue length monitoring offset value of that port is reduced. Thereby, the priority of the port in the queue length monitoring control can be increased. Therefore, it is possible to always perform multiplexing in consideration of both the quality of delay and the quality of discard.

[0013]

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a diagram showing a control method of a multimedia multiplexing system according to an embodiment of the present invention. The cells to be transmitted are stored in separate queues 11, 12, 13 for each quality class. The queue 11 of the port 1 stores cells of a class that is strict about discarding and not strict about delay. The queue 12 of port 2 stores cells of a class that is moderately severe in discarding and delaying. The queue 13 of the port 3 stores cells of a class that is strict in delay and not strict in discarding. Although the number of ports to be set is three in this embodiment, this number can be arbitrarily set depending on the type of media to be multiplexed.

In the figure, (a) and (b) show the operation during polling control. Also, (c) and (d)
Indicates an operation during queue length monitoring control.

First, when polling control is performed
think of. Polling control in this embodiment
Skip to the next port if there is no cell
Ring. Delay to the number of waiting cells for each port
Priority update threshold DL_iSet (i = 1,2,3). Each current po
The number of waiting cells is WC_i(i = 1,2,3). Also, each port
To WC_iValue of WC_iIs the threshold DL_iThe value is 0 when
Hold on and WC_iIs the threshold DL _iWhen it exceeds the
Provided with counters 14, 15 and 16 that count the number of cells
It Each counter value is DC_iIt is indicated by (i = 1,2,3).
DC_iThe initial values of all are 0. Office for polling
The set value is the same as in the conventional example and does not meet the required quality for delay.
Let me PO_iSet (i = 1,2,3). The number of waiting cells is PO_ibelow
In that case, it is assumed that there are no cells accumulated in that port.
Made and not selected. Each port has its own port selected
Then, the cell is output from the queue. At this time, a cue
The number of cells output from the DC_i+1 cell. DC_iThe initial value of
All are 0, so by default, 1 cell from each port
Is output.

It is assumed that cells arrive in the queue 12 of port 2 in bursts. When the number of waiting cells WC2 in the queue 12 is less than or equal to the delay priority update threshold value WC2, the ports in which the number of waiting cells exceeds the polling offset value, that is, the ports 1 and 2 in sequence as shown in FIG. Send cells one by one. However, the number of waiting cells WC2 in the queue 12 eventually increases and exceeds the delay priority update threshold DL2 as shown in FIG. At this time, the value of counter 15 is exceeded by the number of exceeded cells.
Increment the value of DC2. In the figure, since one cell is over, the counter value is incremented by one. When the value of DC2 is increased by 1, the number of cells transmitted when port 2 is selected once is increased by 1. This means that the priority of port 2 in polling control has increased. When the number of waiting cells WC2 becomes equal to or less than the threshold value DL2, the value of the counter DC2 is reset to 0. That is, the number of cells transmitted when port 2 is selected once returns to one cell.

In this embodiment, the number of cells output from the queue when each port is selected is DC _i +1 cells, but for example, the number of cells output when DC _i > 0 is set. The same effect can be obtained by switching to n cells (constant value: n> 1). Therefore, these are not excluded from the scope of the present invention.

Next, consider the case where the queue length monitoring control is being performed. A normal state is shown in FIG. Similar to the polling control, the discard priority update threshold LL _i (i = 1,2,3) is set for the delay time for each port. The delay time at each port is represented by DE _i (i = 1,2,3). DE _i
Indicates the delay time from when each cell is input to the port until it is output from the port. Further, registers 17, 18 and 19 for monitoring the value of DE _i and controlling the queue length monitoring offset value according to the value are provided. The register values are LC _i (i = 1,2,3). The initial values of LC _i are all 0. The queue length monitoring offset value is an initial value, which is the same as in the conventional example.
Set 2, 3). However, actually, the value obtained by subtracting LCi from QOi is used as the true offset value QOi '. That is, QOi '= QOi-LCi (i = 1,2,3) (Equation 1). Since the initial values of LCi are all 0, the initial value is Q
Oi '= QOi. The cell is transmitted from the port with the largest value of the number of waiting cells minus QO _i '. When each port is selected, each port sends out one cell from the queue.

Now, it is assumed that the delay time DE3 of the cell transmitted as shown in FIG. 1 (d) exceeds the threshold LL3 in the queue 13 of the port with severe delay, that is, the port 3. At this time, the value LC3 of the register 19 of the port 3 is set to 10. Since the queue length monitoring offset value QO3 'is expressed by Equation 1,
The value of QO3 'after the increment is 10 smaller than that before the increment shown in FIG. Offset value
The smaller QO3 ', the larger the queue length recognized in the queue length monitoring control. Therefore, the port 3 has a higher priority in the queue length monitoring control. If the delay time is less than the threshold LL3, set the value of LC3 to 0
Reset to. The priority in the queue length monitoring control of port 3 returns to the original state.

In this embodiment, the value of register 19
LC3 is set to 10 when the delay time exceeds the threshold LL3,
When the delay time becomes less than or equal to the threshold value LL3, it is controlled to reset to 0. For example, if a cell that exceeds the threshold value first occurs, the value is set to 10 and 1 is set as cells that exceed the threshold value are continuously transmitted. A control that increments by one is also conceivable. In this case, as the cells exceeding the threshold value are continuously transmitted, the priority in the queue length monitoring control of the port increases.
The same effects can be obtained by such control. Therefore, these are not excluded from the scope of the present invention.

[0021]

As described above, according to the present invention,
Even when delay time priority control such as polling control is performed, the priority of a port that is difficult to discard can be increased by the number of waiting cells at each port. Further, even when the discard rate priority control such as the queue length monitoring control is performed, the delay time of each port can increase the priority of the port that is strict in delay. Therefore, it is possible to perform efficient multiplexing in consideration of both the delay time and the discard rate.

[Brief description of drawings]

FIG. 1 is a diagram showing an operation in a multimedia multiplexing system showing an embodiment of the present invention.

FIG. 2 is a diagram showing an operation in a conventional multimedia multiplexing system.

Claims (1)

[Claims] 1. When a threshold value is set for the number of waiting cells of a port that has a separate queue for each requested quality and the request quality is the most severe, and the number of waiting cells of the port that is the most severe for discard is less than or equal to the threshold value. Sets a polling offset value to all ports so that the value becomes smaller as the request for delay becomes higher, and data is sequentially sent from each port to the port in which the number of waiting cells is larger than the polling offset value. If polling control is performed and the number of waiting cells of the port that is the most severe to discard exceeds the threshold,
A queue length monitoring offset value is set for all ports so that it becomes smaller as the request for discarding becomes higher, and data is sent out from the port with the largest value obtained by subtracting the queue length monitoring offset value from the number of waiting cells. In the multiplex system that performs queue length monitoring control, the delay priority update threshold is set for the number of waiting cells for all ports, and the number of waiting cells for any port is set to the above value when performing the polling control. If the delay priority update threshold is exceeded, increase the number of cells to send when a port exceeding the delay priority update threshold is once selected, and wait cells of the port exceeding the delay priority update threshold. When the number becomes equal to or less than the delay priority update threshold value, the number of cells to be transmitted when the port exceeding the delay priority update threshold value is once selected is returned to the original value, When the discard priority update threshold is set for each delay time for all ports, and the delay time exceeds the discard priority update threshold for any port during queue length monitoring control Reduces the queue length monitoring offset value of the port whose delay time exceeds the discard priority update threshold, and the delay time of the port whose delay time exceeds the discard priority update threshold is the discard priority update threshold A multimedia multiplexing system characterized in that, in the following cases, the queue length monitoring offset value of a port that exceeds the discard priority update threshold is returned to the original value.