JP4219835B2 - Data generation apparatus and data transmission method - Google Patents

Description

  The present invention relates to a data generation apparatus that secures a transmission rate by transmitting data (packets, cells, frames, etc.) at an arbitrary timing on a time axis.

  The data generation device is a terminal that is generally connected to a communication path and can communicate, such as a normal personal computer, and is a device that generates data and transmits the data to the communication path. Such a device measures the processing capability by applying an appropriate data load to a device that transmits data in a fixed data band to the subsequent device or transmission line, and to the device or transmission line. It is also used as a pseudo test device for doing this.

FIG. 4 is a diagram schematically illustrating a conventional data generation apparatus and its operation.
4A, the scheduler 10 has a timer inside, controls the data transmission interval based on the allocated bandwidth, and determines the data transmission rate by making a transmission request to the data generation device 11. To do. The data generated by the data generation device 11 is sent to the transmission device 13 and sent from here to the transmission path.

  When data cannot be transmitted by flow control (flow control (1) in the figure) from the transmission device side, the data generation device 11 temporarily stores the data input from the subscriber side device 14 in the buffer 12, and the data is transmitted. The scheduled data transmission rate is secured by sending the accumulated data when it becomes possible.

FIG. 4B is a timing chart showing the relationship between the conventional data transmission timing and each control.
As shown at the top of FIG. 4B, the data transmission is expected to be regularly transmitted at the time interval t1 when there is no problem. On the other hand, the lower part of FIG. 4B shows the relationship between data input, flow control (1), (2), data transmission, and transmission request when a delay occurs due to flow control. Data entry occurs when a transmission request is issued.

  At timing I, data transmission is delayed due to flow control (1). In this case, data input is normal. However, since the flow control (1) has occurred, the data is accumulated in the buffer 12, and the transmission of data is awaited until the flow control (1) is eliminated. At timing I, data stored in the buffer after the flow control (1) is lost is transmitted. Timing II shows a case where the flow control (1) extends over two data transmission timings. Also at the timing II, when the flow control (1) occurs, the input data is accumulated in the buffer 12 and waits for data transmission until the flow control (1) is completed. When the flow control (1) ends, the data stored in the buffer 12 is sent out, and thereafter, transmission is performed as usual. Here, the capacity of the buffer 12 is twice the data size. That is, two rectangles with diagonal lines indicating the data in FIG. 4B can be buffered. Next, at timing III, the flow control (1) continues for a long time, and the case where data cannot be stored in the buffer 12 is shown. In this case, after the flow control (1) occurs, two pieces of data are stored in the buffer 12, but since the buffer 12 overflows and cannot be stored, the flow control (2) is generated. Then, the subscriber side device 14 is stopped from transmitting data. Therefore, the transmission request during that time is invalidated. When the flow control (1) is eliminated, the data stored in the buffer is transmitted, and thereafter, normal transmission is performed.

Conventional techniques include Patent Document 1 and Patent Document 2. Patent Document 1 discloses a technique for counting the number of signals that could not be transmitted by opening a ranging window and sending the signal with priority over the next transmission opportunity. In Patent Document 2, regarding a digital video stream, when the data stream overflows, a zero packet is added to delay the data portion of the data stream, and when there is no overflow, the zero packet is deleted and the data stream is deleted. A technique for accelerating part of the data is disclosed.
JP 2002-204245 A Japanese translation of PCT publication No. 2002-507375

  However, if the amount of data scheduled in the transmission suspension period by the flow control (1) from the transmission apparatus 13 exceeds the capacity of the buffer 12, data input from the subscriber apparatus 14 is performed until the buffer becomes empty. Since the transmission request from the scheduler 10 becomes invalid, the expected data transmission rate cannot be ensured.

  The range of the transmission stop period in which the expected data transmission rate can be secured depends on the buffer capacity, and in order to double the resistance to flow control from the transmission apparatus side, it is necessary to double the buffer capacity. This increases the scale of the apparatus.

  An object of the present invention is to provide a data generation apparatus and a data transmission method capable of ensuring a long-term scheduled data transmission rate with a smaller apparatus configuration without depending on the buffer capacity.

In the data generation device of the present invention, in the data generation device that transmits data at an arbitrary timing scheduled on the time axis, when the data cannot be transmitted at the scheduled timing, a delay time that the data is delayed is provided. Delay time coefficient means for counting, scheduling means for calculating a transmission rate faster than a normal transmission rate based on the delay time, and scheduling to send delayed data based on the calculated rate;
And a data transmission means for transmitting data according to the schedule.

  According to the data transmission method of the present invention, in the data transmission method in the data generation apparatus which transmits data at an arbitrary timing scheduled on the time axis, the data is delayed when the data cannot be transmitted at the scheduled timing. A delay time coefficient step for counting the delay time, a transmission rate faster than a normal transmission rate is calculated based on the delay time, and scheduling is performed so that delayed data is transmitted based on the calculated rate. A scheduling step; and a data transmission step of transmitting data according to the schedule.

  According to the present invention, it is possible to provide a small-sized data generation device and a data transmission method capable of maintaining a data transmission rate at a scheduled value on average without preparing a buffer for absorbing delay. I can do it.

In the embodiment of the present invention, the following means are used.
Does not have a buffer for absorbing the transmission stop period, measures the time (delay time) when data could not be transmitted at the timing to be transmitted, and transmits the data by subtracting the accumulated time from the next transmission timing .

As described above, the data transmission rate is temporarily accelerated by shortening the data transmission cycle by the delayed time, and as a result, a long-term data transmission rate can be ensured.
Further, independent control can be performed for each channel only by the data transmission propriety information by flow control without being influenced by the contention resolution method in the subsequent transmission apparatus.

  Furthermore, the range of the transmission stop period in which the expected data transmission rate can be ensured depends on the upper limit (number of bits) of the timer for measuring the delay time, but in order to double the resistance to flow control from the transmission apparatus side. Can be realized simply by increasing the number of digits of the timer by one bit, so that the configuration can be simplified and downsized.

FIG. 1 is a block diagram of a data generation device according to an embodiment of the present invention.
The data generation device 20 includes a data reception processing unit 24 that processes a received data frame, and a frame generation processing unit 25 that regenerates the received data frame and transmits it to a transmission path. The frame generation processing unit 25 receives a data transmission request from a scheduler (not shown), and transmits a data frame based on a control signal from the data generation control unit 22 that notifies the scheduler of transmission completion. The data generation control unit 22 receives the flow control signal from the upstream, and sends and receives the control signal to and from the transmission permission signal generation unit 23 that generates the transmission permission signal of the data frame, and transmits the data at an appropriate timing. . The timing generator 21 includes a clock and the like, and gives operation timing to each block of the data generation device 20.

FIG. 2 is an explanatory diagram of an embodiment of the present invention.
In FIG. 2A, the scheduler 10 has an internal timer, manages time information (t1) from the data transmission cycle to the next transmission timing, and determines the next data transmission timing. When the transmission completion of the immediately preceding data is received at the obtained data transmission timing and the flow control (1) is not input from the transmission apparatus side, a transmission request is made to the data generation apparatus 11.

  The data generation device 11 controls the flow control information (2) to the subscriber side device 14 according to the request from the scheduler 10, and notifies the scheduler 10 of the completion of transmission when the data transmission is completed.

  If the condition is not satisfied in the scheduler 10 (transmission stopped state) and a transmission request cannot be made at the data transmission timing, the time until the transmission request can be made is measured and set as a delay time. This time measurement is performed by the delay measurement timer 30.

When the scheduler 10 calculates the data transmission timing, the subsequent transmission timing can be advanced according to the amount of accumulated delay by subtracting the accumulated delay information.
If the delay information accumulation is larger than the time until the next data transmission timing, the next transmission request is made at the minimum interval (t2), and the difference (t1-t2) from the original transmission interval is calculated as the delay information accumulation. By subtracting from, the delay can be absorbed over a plurality of transmission periods.

FIG. 2B is a timing diagram of data transmission according to the embodiment of the present invention.
As shown in FIG. 2B, when flow control does not occur, data is sent out regularly at a time interval t1. On the other hand, when a delay occurs due to the flow control (1), the flow control (2) is also delayed as shown in the timing I portion, and the transmission request and data input are delayed. Then, when the flow control (1) is eliminated, the waited data is transmitted at a high speed for the delayed time. In the case of the timing I, since there is one waiting data, if the delay time is d1, the waiting data is transmitted during the time t1-d1 after the flow control (1) is lost. In the case of the timing II, the case where two data are waited is shown. In this case, data transmission is stopped until the flow control (1) is eliminated, and the waited data is transmitted after the flow control (1) is eliminated. At this time, assuming that the delay time is d2, data is sent one by one every t2 hours after the flow control (1) disappears, and the last data is t1- (d2- (t1- t2)) Complete sending in time. In the case of timing III, the waiting time by the flow control (1) straddles the transmission timing of the four data, and the delay time is d3. The waited data is sent at t2 intervals after the flow control (1) is lost. However, in this case, even if the timing of the fifth data is reached, transmission of the waited data does not end, so that the fifth data is also waiting for transmission. Then, the sequentially waited data is sent up to the fifth data at time interval t2, but since the fifth transmission time t2 is related to the transmission time of the sixth data, there are also five sixth data. After the transmission time of the eye data, it is transmitted during the time t1 × 5- (d3−t2 × 5). After that, it is the same as normal data transmission.

FIG. 3 is a flowchart illustrating the operation of the scheduler according to the embodiment of the present invention.
First, in step S10, the accumulated delay value and the delay timer are reset to zero. In step S11, it is determined whether the sum of the accumulated delay value and the delay timer value is less than or equal to the accumulated delay maximum value. If it is determined in step S11 that the sum is larger than the delay accumulated maximum value, in step S12, the delay accumulated maximum value is set as the delay accumulated value, the delay timer is set to 0, and the process proceeds to step S14. If it is determined in step S11 that the sum is equal to or less than the delay cumulative maximum value, in step S13, the sum of the delay cumulative value and the delay timer value is set as the delay cumulative value, and the delay timer is set to zero. Then, the process proceeds to step S14. In step S14, it is determined whether the accumulated delay value is greater than or less than the value obtained by subtracting the minimum time interval t2 required for data transmission from the normal data transmission interval t1. If the accumulated delay value is larger than the difference, in step S15, t2 is set in the schedule timer, the accumulated delay value-(t1-t2) is set in the accumulated delay value, and the process proceeds to step S17. If it is determined in step S14 that the accumulated delay value is equal to or less than the difference, in step S16, the t1-delay accumulated value is set in the schedule timer, the accumulated delay value is set to 0, and step S17. Proceed to

  In step S17, it is determined whether or not the schedule timer is zero. If the determination in step S17 is No, in step S22, the schedule timer is decremented by 1 and the process proceeds to step S17. If the determination in step S17 is Yes, it is determined in step S18 whether or not transmission completion has been received. If the determination in step S18 is not received, the delay timer is incremented by 1 in step S21, and the process proceeds to step S17. If the determination in step S18 has been received, it is determined in step S19 whether there is flow control (1) ('H') or not ('L'). As a result of the determination in step S19, when it is determined that the flow control (1) is 'H', the process proceeds to step S21. If it is determined as a result of the determination in step S19 that the flow control (1) is 'L', a transmission request is made in step S20, and the process returns to step S11.

  According to the present embodiment, it is possible to ensure the expected data transmission rate with a smaller apparatus configuration without depending on the buffer capacity.

It is a block block diagram of a data generation device according to an embodiment of the present invention. It is explanatory drawing of one Embodiment of this invention. It is a flowchart explaining operation | movement of a scheduler according to embodiment of this invention. It is a figure which illustrates the conventional data generation apparatus and its operation | movement roughly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Scheduler 11, 20 Data generation apparatus 13 Transmission apparatus 14 Subscriber side apparatus 21 Timing generator 22 Data generation control part 23 Transmission permission signal generation part 24 Data reception process part 25 Frame generation process part 30 Delay measurement timer

Claims (3)

In the flow control of data from the transmission device to the data generation device, when a delay occurs in data transmission, a method is adopted in which data transmission from the subscriber device is stopped by flow control from the data generation device to the subscriber side device. In a data generation device for sending data at an arbitrary timing scheduled on the time axis,
A delay time counting means for counting a delay time in which the data is delayed when the data cannot be transmitted at the scheduled timing;
Scheduling means for setting a transmission rate faster than a normal transmission rate based on the delay time, and scheduling to transmit data delayed based on the set rate;
Data transmission means for transmitting data according to the schedule;
A data generation device comprising: In the flow control of data from the transmission device to the data generation device, when a delay occurs in data transmission, a method is adopted in which data transmission from the subscriber device is stopped by flow control from the data generation device to the subscriber side device. In the data transmission method in the data generation device for transmitting data at an arbitrary timing scheduled on the time axis,
A delay time counting step for counting a delay time in which the data is delayed when the data cannot be transmitted at the scheduled timing;
A scheduling step of setting a transmission rate faster than a normal transmission rate based on the delay time and scheduling to send data delayed based on the set rate;
A data transmission step of transmitting data according to the schedule;
A data transmission method comprising: In the flow control of data from the transmission device to the data generation device, when a delay occurs in data transmission, a method is adopted in which data transmission from the subscriber device is stopped by flow control from the data generation device to the subscriber side device. In the data transmission method in the data generation device for transmitting data at an arbitrary timing scheduled on the time axis,
A delay time counting step for counting a delay time in which the data is delayed when the data cannot be transmitted at the scheduled timing;
A scheduling step of setting a transmission rate faster than a normal transmission rate based on the delay time and scheduling to send data delayed based on the set rate;
A data transmission step of transmitting data according to the schedule;
A program for causing a computer to implement a data transmission method characterized by comprising:

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