JPH04100454A - Method of packet communication - Google Patents

Abstract

PURPOSE:To prevent a decline in communication efficiency of the title method by throwing away packet data after a single reading and reducing the value of a data read-and-throw variable by one whenever the data are received when the read-and-throw variable is one or larger and restarting the storage of received packet data in a reception buffer when the data read-and-throw variable becomes zero. CONSTITUTION:When no data exist in a reception buffer 34 at the next readout timing, P=0 is set and the value of a data read-and-throw variable C becomes '1'. Thereafter, the variable C increases one by one whenever readout timing comes and reaches '4'. Dummy readout is successively performed whenever packets arrive and the value of the variable C successively decreases and reaches '0' when the 13th packet data R are thrown away, but, since the readout timing comes soon, the variable C again becomes '1' and the 14th received packet data R are thrown away.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a packet communication method for communicating information using packets.

BACKGROUND OF THE INVENTION In general, this type of packet communication method is implemented in a device connection as outlined in the third (!l). In other words, in FIG. The packet is transmitted through the packet communication network 32 to the receiving device 33.

However, since the packet propagation delay time of the packet communication network 32 is not constant, the receiving device 33 puts the packet data R into the -H receiving buffer 34 and reads the data after it has been accumulated to a certain extent to obtain the received packet data R. I have to.

As a result, even if there is fluctuation in the packet propagation delay time of the packet communication network 32, the data i in the reception buffer 34
By simply increasing or decreasing the received packet data R, the reading speed of the received packet data R can be maintained at a constant speed.

Conventionally, in this type of packet communication, when transmitting audio information, the transmitting device 31 adds consecutive numbers (sequence numbers) to the packets and sends the packets, and the receiving device 33
Now, the expected value N of the sequence number of the packet to be read out from the reception buffer 34 is obtained, and the readout is performed while checking the expected value N and the sequence number of the packet actually read out.

This is in case the packet transmission delay time fluctuation becomes so large that it cannot be absorbed by the reception buffer 34. This will be explained below based on the flowchart of FIG. 4, which explains the conventional packet communication method, and the timing chart of FIG. 5, which shows the operation when some packets arrive at the receiving side with a delay. do.

In FIG. 5, the packet with sequence number 1.2.3 arrived normally, but the packet with sequence number 4.5.6 arrived normally.
．． The operation when packet No. 7 is delayed is explained.

Further, the fluctuation absorption lY in the reception buffer 34 of this conventional example is set to 2. Further, in FIG. 4, E is the sequence number of the packet that is about to be read out next from the reception buffer 34, N is the expected value, and P is the sequence number of the packet that is about to be read out from the reception buffer 34.
This is the number of received packet data accumulated in 4.

As shown in Figure 4, when communication starts, step 4-1
At this point, the device is initialized, and along with this, the expected value N, sequence number E, and number P of accumulated data in the reception buffer 34 are cleared to O.

Then, the accumulation of arriving data in the reception buffer 34 is started, and when the packet with sequence number 2 arrives,
Since two packets of data have been accumulated in the reception buffer 34, the initialization phase is now completed.

Next, in step 4-2, it is determined whether it is the timing to read, and if YES, it is determined in step 4-3 whether or not there is accumulated data P in the reception buffer 34, and if there is accumulated data, step After reading the data from the reception button 734 in step 4-4 and adding 1 to N in step 4-5, the judgment in step 4-2 is
.

The judgment in step 4-2 is repeated in the same way as in the case of .

On the other hand, in step 4-3, if there is no accumulated data of the received baptism 734, the process moves to step 4-6 and the variable N
After adding 1 to , it is determined in step 4-7 whether or not it is the timing to read out, and if YES, step 4-7 is performed.
8, the variable N is calculated by 121III, and if the determination in step 4-7 is NO, it is determined in step 4-9 whether or not there is data accumulated in the reception buffer 34 at the present time.

If it is determined in step 4-9 that there is accumulated data, it is determined in step 4-10 whether N=E, and if YES, the process returns to step 4-2 and the sequence number 1 is set at the read timing. The received packet data R of sequence number 2.3 is read out in the same manner.

On the other hand, if N=M is not true in step 4-10, dummy reading is performed in step 4-11, and when the determination in step 4-9 is No, step 4-7
, and repeat the above operation.

However, in the case shown in FIG. 5, there is no data in the reception buffer 34 at the next read timing, and the packet with sequence number 4 arrives when the expected value N is 5. Therefore, since N≠E, dummy reading is performed and the data of the packet with sequence number 4 is discarded. For the next packet with sequence number 5,
Since the corresponding read timing is met, the data is read normally.

In this way, even with the above conventional packet communication method,
Packets can be sent and received normally except for large consecutive packets.

Problems to be Solved by the Invention However, in the conventional packet communication method described above, a sequence number must be added at the transmitting device, which increases packet redundancy and reduces communication efficiency. .

In addition, if the initial setting value of the amount of fluctuation absorption Y in the receiving device is small, or if the fluctuation congestion of the packet communication network increases during operation, the amount of data delay will increase and data will be frequently discarded. There was also the problem of becoming

The present invention is intended to solve such conventional problems, and its first purpose is to provide a packet communication method that does not require assigning sequence numbers and can prevent a decrease in communication efficiency. , its second purpose is to provide a packet communication method that can reduce the packet delay l by changing the fluctuation absorption capacity for each communication, thereby reducing the amount of discarded data. It's about doing.

Means for Solving the Problems In order to achieve the above-mentioned first object, the present invention starts accumulating received packet data in a receiving buffer immediately after the start of communication, and accumulates received packet data in an amount necessary for absorbing delay fluctuations. Sometimes, there is a packet communication method in which the received packet data is read out one packet at a time at regular intervals, and at the start of communication, a data readout variable is defined as 0, and when the above-mentioned receive buffer 7 is empty, the iU When the reading timing has come, the data reading discarding variable which is the initial value O is set to 1, and thereafter, the value of the variable is increased by 1 each time the reading timing comes, and the reading discarding variable is at least 1 or more. Sometimes,
Each time the received packet data is received, the data is read out from the receive buffer, and the value of the read-out variable is decreased by 1. When the value of the read-out variable becomes ○, the received packet data is stored in the receive buffer again. Initially, when the amount of received packet data necessary for absorbing delay fluctuations has been accumulated, the received packet data is read out one packet at a time at regular intervals thereafter.

Furthermore, in order to achieve the first object, the present invention stores the value of the discarded variable until the discarded variable becomes O again when the discarded variable becomes at least 1, When the above-mentioned discard variable decreases to O, reception of received packet data in subsequent communication is performed based on the value of the above-mentioned stored discard variable.1. The amount of fuel injection into the fa is now determined.

Effects According to the first invention, with the above configuration, it is possible to discard or read data without assigning a sequence number to received data and checking it with an expected value, thereby preventing a decrease in communication efficiency. .

Further, according to the second invention, with the above configuration, the next fluctuation absorption capacity can be set based on the number of discarded data from the previous time, so the fluctuation absorption capacity can be changed for each communication. , the amount of packet delay can be reduced, and the amount of discarded data can be reduced.

Embodiment FIG. 1 is a flowchart explaining a packet communication method according to an embodiment of the present invention, and FIG. 2 is a timing chart showing the operation when some packets arrive at the receiving side with a delay. .

In addition, in Figure 2, the 12th, 13th, and 14th
The 15th packet arrived normally, but after the 15th packet, the 1st packet arrived normally.
The operation when six packets 5-O to 15-5 are connected is explained.

Note that the fluctuation absorption amount Y was set to "2". Further, in FIG. 1, P is a variable indicating the number of packet data stored in the reception buffer 34, and C is a data discard variable.

The operation of the first embodiment of the present invention will be explained below.

In packet communication from the transmitting device 31 to the receiving device 33 via the packet communication network 32 as shown in FIG. 3, when communication starts as shown in FIG. Along with this, the data readout variable C and the number P of accumulated data in the reception buffer 34 are cleared to O.

Then, the accumulation of the arriving data in the reception buffer 734 is started, and when the 13th packet arrives, the data for 2 packets has been accumulated in the reception buffer 34, so the initialization is started. Finish the phase.

Next, in step 12, it is determined whether it is the timing to perform reading. If YES, it is determined in step 1-3 whether or not there is accumulated data P in the reception buffer 34, and if there is accumulated data, it is determined in step 1-3. After reading the received packet y) data R from the reception buffer 34 in Step 4, the judgment in Step 1-2 is repeated in the same way as when the judgment in Step 1-2 is No.
The 14th and 14th received packet data R are read out.

On the other hand, if the judgment in step 1-3 is NO, the process moves to step 1-5, in which the data readout variable C is incremented by one, and then in step 1-6 it is judged whether it is the timing to perform the readout, and the judgment is YES. In this case, the data discard variable C is added by one, and if the determination in step 1-6 is No, it is determined in step 17 whether there is any accumulated data in the reception buffer 34.

If the judgment in step l-7 is YES, it is judged in step 1-8 whether the data discard variable C is O, and in the case of YES, the process returns to step 12 and no
In this case, perform dummy reading in step l-9, subtract 1 from variable C in step 1-10, and then perform step 1-1.
If the determination in Step 8 is No, the determination in Steps 1-6 is repeated.

However, in the case shown in FIG. 2, there is no data in the reception buffer 34 at the next read timing, so P=
0, and the value of the data discard variable C becomes "l".

After that, since no packets arrive for a while, the data readout variable C increases to "4" every time the read timing comes.

Thereafter, when a packet arrives, the data number P is no longer O, so dummy reading is performed. When a dummy read is performed, the f-number P should be O, but in reality, the number P of data is always larger than O because the par/r metes arrive one after another, and the dummy read is performed one after another. It will be held in As a result, the value of the data discard variable C gradually decreases.

Then, when the 13th received packet data R is discarded, the data discard variable C becomes ○, but the read timing comes soon, so the data discard variable C
becomes 1 again, and the 14th received packet data R is discarded.

Therefore, the value of the data discard variable C becomes O again, so
The next dummy read is not performed, and the 15th and subsequent 15-0 to 15-5 received packet data R are correctly read at the original read timing.

In this way, according to the above embodiment, the variable C indicates the number of times dummy reading should be performed, but this can be easily obtained from the easily obtained values of the number of read timings and the number of times dummy reading is performed. It has the advantage of being able to obtain two things.

Furthermore, by utilizing the fact that the maximum value of the variable C in one communication by a plurality of packet transmissions corresponds to the maximum value of propagation delay fluctuation of the packet communication network, the reception buffer 3
In a second embodiment of the present invention described below, the amount of accumulated data is determined.

In the second embodiment, when a packet delay as described above occurs, the maximum value Cmax of the data readout variable C is stored, and when the state returns to normal data readout, the stored data readout variable The value obtained by multiplying the maximum value Cmax of C by a predetermined number and converting it into an integer is
In addition to the fluctuation absorption amount Y used in the previous communication, this is set as the value of the new fluctuation absorption amount Yc.

Therefore, the larger the maximum value Cmax of the read variable C,
In other words, the larger the amount of fluctuation, the new fluctuation absorption 1
The value of kYc is automatically set large. Furthermore, if the maximum value Crnax of the read variable C is O, there is a possibility that the fluctuation absorption l is too large, so the fluctuation absorption amount Yc in the next communication is reduced by 1.

In this way, even if the delay fluctuation of the packet communication network changes, it is possible to obtain the necessary and sufficient amount of fluctuation absorption that follows it.

In addition, in the second embodiment, the new fluctuation absorption amount YC to be used for the next communication does not need to be in a proportional relationship with the maximum value Cmax of the read variable C, but is determined as a function of the maximum value Cmax of the read variable C. You can define
It may be determined not only from the maximum value Cmax of the read variable C but also from the frequency distribution and time change of the variable C in the previous communication.

Furthermore, in the first and second embodiments described above, if an upper limit value is set for the data read variable C, when the data read variable C exceeds this upper limit value, a failure such as input interruption of the received packet data R occurs. As a result, it is possible to issue an alarm, etc.

Effects of the Invention According to the first invention as described above, received packet data starts to be accumulated in the receive buffer immediately after the start of communication, and when the amount of received packet data necessary for absorbing delay fluctuations has been accumulated, the data is stored at a constant level from then on. This is a packet communication network method in which received packet data is read out one packet at each interval readout timing, where the data readout variable is defined as 0 at the start of communication, and the readout timing occurs when the abovementioned reception buffer is empty. In this case, the data read-out variable with the initial value of 0 is set to 1, and thereafter, the value of the variable is increased by 1 at each read timing, and when the read-out variable is at least 1 or more,
Each time the received packet data is received, the data is read out from the receive buffer, and the value of the read-out variable is decreased by 1. When the value of the read-out variable becomes ○, the received packet data is read out into the receive buffer again. Therefore, when the amount of received packet data necessary for absorbing delay fluctuations has been accumulated, the received packet data is read out one packet at a time at regular intervals.

Therefore, the data can be discarded or read without giving the received data a sequence number and comparing it with the expected value, thereby preventing a decrease in communication efficiency.

Further, as described above, according to the second invention, when the above-mentioned discarded variable becomes at least 1 or more, the value of the discarded variable is stored until the discarded variable becomes O again, and the above-mentioned discarded variable is stored. When the variable decreases to O, the accumulation i of received packet data in the reception buffer in subsequent communication is determined based on the value of the stored discarded variable.

Therefore, it is possible to set the next fluctuation absorption capacity based on the number of discarded data from the previous time, so it is possible to change the fluctuation absorption capacity for each communication, thereby reducing the amount of packet delay. In addition to being able to
The amount of discarded data can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a flowchart explaining a packet communication method in an embodiment of the present invention, FIG. 2 is a timing chart explaining the operation of the packet communication method of FIG. 1, and FIG. 3 is a general packet communication method. FIG. 4 is a flowchart explaining the conventional packet communication method, and FIG. 5 is a timing chart explaining the operation of the packet communication method shown in FIG. 34...Reception buffer, R...Reception packet data. Figure 1 Agent's name Patent attorney Shige Awano Takahaka 1 person 4 Beji 11・-Marunibeshi 11・-Processing ← Saba 4 figure

Claims (2)

[Claims] (1) Immediately after the start of communication, receive packet data starts to be accumulated in the receive buffer, and when the amount of receive packet data necessary to absorb delay fluctuations has accumulated, from then on, one packet of received packet data is stored at regular intervals of read timing. A packet communication method in which a data readout variable is defined as 0 at the start of communication, and when the readout timing comes when the reception buffer is empty, the data readout variable whose initial value is 0 is defined. 1, and from then on, the value of the variable is increased by 1 at each read timing, and when the discarded variable is at least 1,
Each time the received packet data is received, the data is read out from the receive buffer, and the value of the read-out variable is decreased by 1. When the value of the read-out variable becomes 0, the received packet data is read out into the receive buffer again. Therefore, when the amount of received packet data necessary for absorbing delay fluctuations is initially accumulated, the received packet data is read out one packet at a time at regular interval readout timings thereafter. (2) When the above-mentioned discarded variable becomes at least 1, the value of the discarded variable is stored until the discarded variable becomes 0 again, and when the above-mentioned discarded variable decreases to 0, 2. The packet communication method according to claim 1, wherein the amount of received packet data to be stored in the reception buffer in subsequent communication is determined based on the value of the stored discarded variable.