JP2001086190A - Error control system in data transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an error control system in effective data transmission even in a transmission system whose communication environment is not excellent. SOLUTION: In this error control system, contents 1 are sent to a reception station R, and when a reception discrimination block 6 returns a NAK signal, a packet length control block 2 receives a packet of the contents 1 from a transmission buffer memory 9 to reconfigure the packet. In order to reduce the length of the packet, the contents 1 are divided at a proper position. Reducing the length of the packet can enhance possibility of reception without an error. Then the divided contents are fed to a protocol conversion block 3, a header, a tailer and a check sum are added to each packet, the resulting packets are fed to a transmission processing block 4, which retransmits the packets.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for controlling an error in a transmission system in data communication.
The present invention relates to an error control system that retransmits information to a receiving station when the information is not correctly transmitted from the transmitting station to the receiving station.

[0002]

2. Description of the Related Art The most important functions in data communication are:
That is, data to be communicated is correctly transmitted to the receiving station. However, an error often occurs in data when exchanging data between information devices. In particular, in a transmission system such as a transmission line or a transmission device, data to be communicated is likely to cause errors due to noise from other electronic devices or physical interruption.

Therefore, many error control systems for detecting and correcting data errors in a transmission system have been devised. There are various types of error control systems in data transmission. For example, a receiving station returns received data to a transmitting station as it is, and the transmitted data is compared with the transmitted data at the transmitting station to determine whether there is an error. An information feedback system or an error correction system (fo) in which a code having an error correction capability is added to transmission data in advance and a receiving station automatically corrects errors at the time of decoding.
rward error control system).

[0004] Among them, an automatic retransmission request method (automatic retransmission request method) is mainly used at present in data communication.
repeat request system: ARQ scheme). According to this method, a transmitting station adds an error detection code to transmission data in advance, and the receiving station checks the error detection code to detect the presence or absence of an error. An ACK (acknowledgement) signal indicating that the receiving station has successfully received the transmission data depending on the presence or absence, or a NAK indicating that the transmission data has an error.
One or both of the (negative acknowledgment) signals are returned to the transmitting station. The transmitting station automatically retransmits the data when it determines that the transmitted data has not been correctly transmitted to the receiving station.

There are several types of ARQ schemes. FIG. 5 shows Stop-and-W which is the most basic ARQ scheme.
FIG. 3 is a diagram illustrating a state of data communication by the ait method.
Data to be communicated is transmitted from the transmitting station in packet units. Here, a packet refers to a group of information blocks obtained by dividing transmission data by an appropriate data length. A packet often includes one or both of a header including protocol control information such as a transmission destination address and a transmission path, and a tailor indicating the end of data.

According to the Stop-and-Wait system, the transmitting station transmits one packet and then transmits an ACK from the receiving station.
The transmission is suspended until either the signal or the NAK signal is received. Then, upon receiving the ACK signal, the next packet is transmitted, and upon receiving the NAK signal, the same packet is retransmitted.

FIG. 5 shows an example in which packets 1, 2, and 3 are transmitted. In this figure, packet 1 has been correctly received by the receiving station, and an ACK signal has been returned from the receiving station to the transmitting station. Therefore, the transmitting station that has received the ACK signal subsequently transmits packet 2.
On the other hand, in the packets 2 and 3, an error has been detected in the receiving station, and a NAK signal is returned from the receiving station to the transmitting station. Therefore, the transmitting station that has received the NAK signal retransmits the same packet.

[0008] Since the reception status is returned each time one packet is transmitted, data to be communicated can be more accurately transmitted to the receiving station by using the ARQ system.

In addition to the Stop-and-Wait method, Go-ba
There is also a continuous ARQ scheme that does not interrupt transmission, such as the ck-N scheme and the Selective-Repeat scheme. Go-back-N method
As shown in FIG. 6, when a transmitting station continuously transmits a packet and receives a NAK signal, the transmitting station goes back by N packets to the point where an error is detected and retransmits the packet again. Further, as shown in FIG. 7, the Selective-Repeat scheme is a scheme in which the Go-back-N scheme is improved and only packets in which an error is detected are retransmitted.

In addition, the ACK signal or the NAK signal is not returned because the transmission data does not reach the receiving station, or the ACK signal or the NAK signal is returned from the receiving station but does not reach the transmitting station. In consideration of the case, a timer is provided in the transmitting station, and after transmission, if there is no response from the receiving station even after a certain period of time, retransmit,
There is also a timer method.

[0011]

In the above-described conventional error control systems, such as the ARQ system, it is difficult to maintain a stable communication state, for example, when a wireless transmission line is used. It was not necessarily effective for transmission systems with poor communication environments. In such a transmission system, the transmitting station cannot easily receive the ACK signal from the receiving station, so that the same packet continues to be retransmitted many times, so that subsequent data is not transmitted to the receiving station or the amount of data to be retransmitted. This is because there is a problem that the buffer memory for storing the transmission data overflows immediately due to an excessive increase in the transmission data.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to realize an error control system in data transmission that is effective even for a transmission system having a poor communication environment.

[0013]

Means for Solving the Problems Claim 1 of the present invention
The transmitting station includes a transmitting station that transmits data in packet units, and a receiving station that receives the data. The transmitting station transmits the data to the packet length according to the success or failure of the data reception at the receiving station. Is an error control system in data transmission that changes and resends.

According to a second aspect of the present invention,
2. The error control system in data transmission according to claim 1, wherein the receiving station determines whether each packet of the data is successfully received, and notifies the transmitting station of each determination result. When the result indicates that the reception of the packet is unsuccessful, the transmitting station changes the packet length of the data by dividing the packet and generating a new packet.

According to a third aspect of the present invention,
3. The error control system in data transmission according to claim 2, wherein the packet includes a plurality of contents, and each of the plurality of contents is provided with priority information according to a degree of need to reach the receiving station. And the plurality of contents are arranged based on the priority.

According to a fourth aspect of the present invention,
4. The error control system in data transmission according to claim 3, wherein the receiving station determines whether each of the plurality of contents has been successfully received, and determines a result of the determination based on the priority of each of the plurality of contents. Notify the transmitting station using information, and when the determination result indicates that reception of the content whose priority is equal to or higher than a predetermined value is unsuccessful, the transmitting station selects the content and The packet length of the data is changed by generating a new packet.

According to a fifth aspect of the present invention, there is provided:
5. The error control system in data transmission according to claim 4, wherein the receiving station determines success or failure of reception within a packet even at a layer higher than the plurality of contents.

According to a sixth aspect of the present invention,
6. The error control system in data transmission according to claim 1, wherein the transmitting station overlaps a buffer memory for temporarily storing the data and an auxiliary memory for storing the contents of the buffer memory. And a device.

According to a seventh aspect of the present invention,
7. The error control system for data transmission according to claim 1, wherein the transmitting station further includes a timer that measures an elapsed time from a transmission time of each packet of the data.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 In this embodiment,
If the communication environment of the transmission system is good, the packet length can be changed according to the reception condition so that the transmission is performed with a large packet length, and if the communication environment of the transmission system is poor, the transmission is performed with a small packet length. Thus, an error control system in data transmission is provided.

In general, if the packet length is large, a large amount of information can be transmitted at one time, so that the transmission efficiency is good. But,
If the packet length is large, there is a high possibility that an error occurs somewhere in the packet due to the influence of noise or the like. Conversely, if the packet length is small, the transmission efficiency is reduced, but the possibility of occurrence of an error is low.

Therefore, in the present embodiment, the same packet as the packet transmitted once is not retransmitted as in the conventional error control system, but the packet length is changed and retransmitted.

FIG. 1 is a block diagram illustrating an error control system in data transmission according to the present embodiment, taking an ARQ system as an example. In FIG. 1, the content 1 is shown as data transmitted from the transmitting station S to the receiving station R.

First, at the transmitting station S, the content 1 is input to the packet length control block 2. The packet length control block 2 changes the packet length by dividing the content 1 in the retransmission stage, but sends the content 1 to the protocol conversion block 3 without changing the packet length at the first data transmission.

In the protocol conversion block 3, a header and a tailer are added to the content 1. Then, a packet is generated by further adding, for example, a checksum in which data length information is recorded as an error detection code. FIG.
The packet P1 shown in FIG. In FIG. 2, the packet P1 has a header HD before the content 1 and a tailor TL after the content 1. Also, the packet P
1 has an individual checksum for each of the content 1 and the header HD. That is, a checksum CS0 that records information on the data length of the content 1,
Checksum C that records information on the data length of the header HD
Sh is provided.

After the packet is output from the protocol conversion block 3 to the transmission processing block 4, the packet is transmitted as transmission data from the transmission processing block 4 to the receiving station R via the transmission path P.

At this time, the packet is also output from the protocol conversion block 3 to the transmission buffer memory 9 and
Transmission buffer memory 9 for reference during packet retransmission
Is stored temporarily.

The packets recorded in the transmission buffer memory 9 may be stored in an auxiliary storage device 10 such as a magneto-optical disk. Auxiliary storage device 10
If you want to send the same data again after a period of time, or if you want to certify the contents of the transmission, you can store not only the transmission history of the packet but also its contents for a long period of time. Can be used.

Subsequently, in the receiving station R, the reception processing block 5 receives the transmission data. The received packet is sent from the reception processing block 5 to the reception determination block 6,
The reception determination block 6 compares the checksum value with the data length of the actually received packet to determine whether an error has occurred during transmission.

Taking the packet shown in FIG. 2 as an example, it will be described whether the actual data length of the received header HD matches the data length information recorded in the checksum CSh, and whether the received content 1 It is determined whether or not the actual data length of the data and the information of the data length recorded in the checksum CS0 match.

As a result, if there is no error, the reception judgment block 6 continues the reception processing (data distribution and data rearrangement at the reception station R) in the reception processing block 5. Also, an ACK signal is transmitted to the transmitting station S to notify the transmitting station S that the transmission data has been received without error.
Tell through. If there is an error, the reception processing in the reception processing block 5 is stopped, and a NAK signal is transmitted to the transmitting station S to notify the transmission station S that the transmission data has an error.

The reception determination block 6 is set to transmit the NAK signal to the transmitting station S only when there is an error in the transmission data, or to transmit the ACK signal to the transmitting station S only when there is no error. It may be.

At the transmitting station S, ACK / NAK
The signal reception block 7 receives the ACK from the reception determination block 6
Receive a signal or NAK signal. If the receiving station R has received the transmission data without error, there is no need for retransmission, so the previous packet stored in the transmission buffer memory 9 is deleted. On the other hand, if there is an error in the data received by the receiving station R, a retransmission instruction is given to the transmission buffer memory 9 to retransmit the previous packet. As a result, the transmission buffer memory 9 sends the data of the previously sent packet to the packet length control block 2. ACK / NAK
The signal receiving block 7 notifies the packet length control block 2 whether to perform retransmission or non-retransmission.

The ACK / NAK signal receiving block 7
Is provided with a timer 8 for measuring the elapsed time from the packet transmission time point in consideration of the case where the ACK signal or the NAK signal cannot be received. ACK / N if no response
The AK signal receiving block 7 may be given a retransmission command. The timer 8 can recognize the transmission time point by monitoring the input time point of the transmission data from the protocol conversion block 3 to the transmission buffer memory 9, for example.

Further, if the timer 8 is provided, if the reception determination block 6 is set to transmit only the ACK signal, the ACK is automatically transmitted if the ACK signal does not come within a certain time after the transmission. The / NAK signal receiving block 7 can issue a retransmission command to the packet length control block 2 and the transmission buffer memory 9. Similarly, if the reception determination block 6 is set to transmit only the NAK signal, the NA
If the K signal does not come, the ACK / NAK signal receiving block 7 can automatically issue an erase command.

Further, if there is a timer 8, regardless of whether an ACK signal or a NAK signal is received, an erasing command is issued from the ACK / NAK signal receiving block 7 to the transmission buffer memory 9 when a predetermined time has elapsed from the transmission. It is also possible to do so.

For example, if the timer 8 is used, ACK
The / NAK signal receiving block 7 can also delete the transmission data in the auxiliary storage device 10 after storing it for a desired period. Conversely, after the transmission data is stored in the auxiliary storage device 10 for a desired period, the data can be recalled to the transmission buffer memory 9 and retransmitted.

In the ACK / NAK signal receiving block 7, for example, the number of retransmission instructions for the same packet is counted, and an erasing instruction is issued to the transmission buffer memory 9 when the number exceeds a certain number. Is also good.
In this way, it is possible to prevent the subsequent packet from being sent to the receiving station because the same packet is continuously retransmitted many times.

Now, the packet length control block 2
When the non-retransmission notification is received from the K / NAK signal reception block 7, the content 1 to be transmitted next is transmitted to the protocol conversion block 3 as it is, and the transmission is repeated, as in the case of the previously transmitted packet.

On the other hand, when the notification of retransmission is received, the packet transmitted earlier is received from the transmission buffer memory 9 and the packet is reconfigured.

FIG. 2 illustrates the reconfiguration of the packet. In order to reconstruct the packet, first, in order to shorten the initially transmitted packet P1, the content 1 is divided at an appropriate place, and the content 1a, 1b
Divided into Then, the packet length control block 2 sends the divided contents 1a and 1b to the protocol conversion block 3.

Then, in the protocol conversion block 3, a header HD and a tailor TL are added to each of the contents 1a and 1b, and each of them is added to a new packet P2.
P3. At this time, for example, in addition to the information such as the transmission destination address, information for notifying the receiving station R of the change in the packet length may be recorded in the header HD. Checksums CSa and CSb respectively corresponding to the contents 1a and 1b are newly prepared and added.
Then, the newly generated packets P2 and P3 are sent to the transmission processing block 4, and the transmission is repeated again.

Then, the receiving station R performs the receiving process and the receiving determination again, and sends an ACK signal or a NAK signal to the transmitting station S as before. Then, the transmitting station S repeats the same processing.

When the transmitting station S retransmits the divided packets P2 and P3 again,
Further, similar packet reconfiguration may be performed. That is,
As shown in FIG. 2, the contents 1a and 1b are further divided into contents 1c to 1f, and each of the contents 1c to 1f has a header HD, a tailor TL, and a checksum C.
Sc to CSf are added, and each is added to a new packet P
4-P7 may be set. Thereafter, when a retransmission request is further received, the same packet reconfiguration as described above may be repeated.

If the error control system in data transmission according to the present embodiment is used, the packet length can be reduced, so that the possibility of occurrence of errors is reduced. Will be more reliable.

According to the present embodiment, conversely, when the communication environment is favorable, a plurality of contents having a short data length can be combined and transmitted as a long packet. In such a case, a plurality of contents may be connected in the packet length control block 2, a packet may be generated in the protocol conversion block 3, and transmission processing may be performed. Then, it is possible to increase the packet length by repeating packet reconfiguration until the ACK / NAK signal receiving block 7 notifies retransmission.

In this case, since the packet length becomes large, a large amount of information can be transmitted at one time, and the transmission efficiency is good.

Embodiment 2 The present embodiment is a modification of the error control system in data transmission according to the first embodiment, and assigns priorities to contents in a packet.

For example, there is a case where a packet contains a content that is always required to reach the receiving station or a content that does not need to reach the receiving station. In this case, as long as the data required to reach the receiving station is received by the receiving station without error, the receiving station can ignore the data even if other data contains an error. Then, the transmitting station may omit the retransmission of the content having a low necessity to reach the receiving station. Further, when an error is included in the content that is required to reach the receiving station and it is necessary to retransmit the content, for example, the content may be added to a packet to be transmitted next time and transmitted together.

In order to realize the above, it is necessary to specify in which part of the packet an error has occurred.

Therefore, in the present embodiment, priority information is added to each content in a packet, and an error detection code is added to each content.

FIG. 3 is a block diagram illustrating an error control system in data transmission according to the present embodiment. In FIG. 3, a plurality of contents 12a to 1 transmitted from the transmitting station S to the receiving station R as one packet are shown.
2d is shown. These contents 12a to 12
Priority is set to each of d.

For example, assuming that the error control system in data transmission according to the present embodiment is applied to a remote monitoring system for security, for example,
Alarm data that gives an alarm to an observer located away from the security place, sensor data indicating information such as temperature sensors and infrared sensors installed in the security place, voice data and image data inside and around the security place Conceivable. For example, if the priorities are higher in the order just described, the priority levels are 1 for alarm data, 2 for sensor data, 3 for audio data, and 4 for image data (the lower the number, the higher the priority level). high). The description below is based on this example.

First, the contents 12a to 12d are input to the packet length control block 2. In the packet length control block 2, the contents 12a to 12
The packet length is changed by selecting which content to be retransmitted out of d. The content 12a to 12d is sent to the priority assignment block 11 as it is at the time of the first data transmission.

In the priority assignment block 11, the contents 12a-1 output from the packet length control block 2 are output.
A level signal having priority information is assigned to each of the 2d. Then, each of the contents 12 a to 12 d to which the level signal is added is sent to the protocol conversion block 3.

In the protocol conversion block 3, a checksum is added to each of the contents 12a to 12d to make a set of data, and then a packet is generated by adding a header and a tailor.

The packet P8 shown in FIG. 4 is an example of the generation. In the packet P8, an individual checksum is provided for each of the contents 12a to 12d and the header HD. That is, the checksum CSh of the header HD
And checksum CS1 of each content 12a to 12d
To CS4.

In the packet P8, priority level signals LV1 to LV4 are assigned to the contents 12a to 12d, that is, alarm data, sensor data, audio data, and image data.

In the packet P8, the contents are arranged in descending order of priority from the header HD. By arranging high-priority content at a position close to the header HD, when the receiving station R has to terminate reception for some reason, the highest-priority content is transmitted to the receiving station R as much as possible. You can keep.

In the packet P8, checksums CSα and CSβ are provided at appropriate places (for example, every two contents) in a higher order than the contents. The checksum CSα records information on the data length from the header HD to the checksum CS2, and the checksum CSβ stores the checksum CS from the level signal LV3.
Information on data lengths up to 4 is recorded. Like the checksums CSα and CSβ, the checksum added in a layer higher than the content section can be used to quickly determine the presence or absence of an error or to roughly identify where in a packet an error exists. This is more useful than checking for each content when you want to know about it. However, these checksums CSα and CSβ can be omitted.

The packet is output from the protocol conversion block 3 to the transmission processing block 4 and transmitted from the transmission processing block 4 to the receiving station R via the transmission path P.
At this time, the packet is also output from the protocol conversion block 3 to the transmission buffer memory 9 and temporarily stored in the transmission buffer memory 9 for reference when retransmitting the packet. The packet recorded in the transmission buffer memory 9 may be further stored in the auxiliary storage device 10.

Subsequently, in the receiving station R, the reception processing block 5 receives the transmission data. The received packet is sent from the reception processing block 5 to the reception determination block 6,
The reception determination block 6 compares the checksum value with the data length of the actually received packet to determine whether an error has occurred during transmission.

Referring to the packet shown in FIG. 4 as an example, if the checksums CSα and CSβ are included in the packet, first, the checksum CS
2 and whether the information on the data length recorded in the checksum CSα matches, and the actual data length from the level signal LV3 to the checksum CS4 and the data recorded in the checksum CSβ It is determined whether the length information matches.

If there is an error at this stage, the reception processing in the reception processing block 5 is stopped, and a NAK signal for notifying the transmission station S that the transmission data has an error is transmitted. At the time of transmitting the NAK signal, a priority level signal of an erroneous portion is added to the NAK signal.
For example, when an error is detected by checking the checksum CSα, for example, information of all the level signals LV1 and LV2 in the section of the checksum CSα is added to the NAK signal. Alternatively, for example, information of the level signal LV1 having the highest priority among the sections of the checksum CSα may be added to the NAK signal. In any case, checksum CS
It suffices if it is possible to identify in which part of the area divided by α and CSβ an error has occurred. Then, the transmitting station S
In the above, the information is used as a material for determining whether to retransmit the packet, what portion should be retransmitted, and how much the packet length should be changed.

If there is no error at the stage of the division by the checksums CSα and CSβ, a check is performed for each content. That is, whether the actual data length of the header HD matches the information of the data length recorded in the checksum CSh, and whether the contents 12a to 12
It is determined whether or not the actual data length of d matches the data length information recorded in the checksums CS1 to CS4.

As a result, if there is no error, the reception judgment block 6 continues the reception processing in the reception processing block 5. Also, an ACK signal is transmitted to the transmitting station S to notify the transmitting station S that the transmission data has been received without error.
Tell through. If there is an error, the reception processing in the reception processing block 5 is stopped, and a NAK signal is transmitted to the transmitting station S to notify the transmission station S that the transmission data has an error. At the time of transmitting the NAK signal, as in the previous case,
The level signal of the erroneous content is added to the NAK signal.

When the checksums CSα and CSβ are omitted, the reception determination block 6 may perform a check in content units from the beginning.

As in the first embodiment, reception determination block 6 transmits a NAK signal to transmission station S only when there is an error in transmission data, or transmits an ACK signal only when there is no error. It may be set to transmit to S. In the former case, the level signal of the erroneous content may be added to the NAK signal as described above.
In the latter case, the AC of the packet received without error is
When transmitting the K signal, the level signal of the content having an error in the previous packet may be added to the ACK signal.

At the transmitting station S, the ACK / NAK signal receiving block 7 receives the ACK signal or the NAK signal from the reception determining block 6. If the receiving station R has received the transmission data without error, there is no need for retransmission, so the previous packet stored in the transmission buffer memory 9 is deleted.

On the other hand, if there is an error in the data received by the receiving station R, the ACK / NAK signal receiving block 7
It is determined whether or not to retransmit from the information of the level signal added to the signal or NAK signal. That is, if the content of the priority higher than the predetermined value is not correctly received, the content is retransmitted.
A retransmission instruction is given to the transmission buffer memory 9. As a result, the transmission buffer memory 9 sends the data of the previously sent packet to the packet length control block 2. Further, the ACK / NAK signal receiving block 7 may give an erasing command to the transmission buffer memory 9 for correctly received content.

The ACK / NAK signal receiving block 7
Informs the packet length control block 2 about retransmission / non-retransmission and which priority content is to be retransmitted.

As in the first embodiment, a timer 8 is provided so that the reception station R
If there is no response from the ACK / NAK signal receiving block 7, a retransmission command may be given to the ACK / NAK signal receiving block 7. Further, if the timer 8 is provided, similarly to the first embodiment, when the reception determination block 6 is set to transmit only the ACK signal or the NAK signal, the ACK signal is transmitted even after a certain time has elapsed from the transmission. Alternatively, the ACK / NAK signal receiving block 7 automatically issues a retransmission command or an erasing command if a NAK signal does not come,
Regardless of whether a K signal or a NAK signal is received, an erasing command can be issued from the ACK / NAK signal receiving block 7 to the transmission buffer memory 9 when a predetermined time has elapsed from the transmission.

Note that, as in the first embodiment, ACK / NA
The K signal receiving block 7 may count the number of retransmission instructions of the same packet, and issue an erasure instruction to the transmission buffer memory 9 when the number exceeds a certain number. In this way, it is possible to prevent the subsequent packet from being sent to the receiving station because the same packet is continuously retransmitted many times. Further, the retransmission may be determined by combining the priority and the number of retransmissions, for example, by increasing the allowable number of retransmissions for a higher priority.

Now, the packet length control block 2
When the non-retransmission notification is received from the K / NAK signal reception block 7, the contents 12a to 12d to be transmitted next are transmitted to the protocol conversion block 3 as they are, and the transmission is repeated, as in the case of the previously transmitted packet.

On the other hand, when the notification of retransmission is received, the packet received from the transmission buffer memory 9 is received and the packet is reconfigured.

FIG. 4 illustrates this packet reconfiguration. In the packet length control block 2, ACK
Based on the priority information notified from the / NAK signal receiving block 7, of the packets sent from the transmission buffer memory 9, the content having the corresponding priority is divided and extracted. Then, the extracted content is sent to the priority assignment block 11. In the priority assignment block 11, each content is re-assigned a priority, rearranged, and sent to the protocol conversion block 3.

Then, in the protocol conversion block 3, a checksum is added to each content, and then each content is grouped and a header and tailor are added to form a new packet. At this time, similarly to the first embodiment, in the header, information for notifying the receiving station R of the change in the packet length is recorded in addition to the information such as the transmission destination address. Then, the newly generated packet is sent to the transmission processing block 4, and the transmission is repeated again.

For example, when it is necessary to always receive the content having the priority of 2 or more in the packet P8 of FIG.
If the content 12a having the priority 1 and the content 12b having the priority 2 are not correctly received,
Headers HD, Taylor TL,
A packet P9 may be generated by adding the checksums CSh, CS1, and CS2, and this may be used as a new packet to be retransmitted. Then, the lower priority contents 12c,
Retransmission of 12d audio data and image data is omitted.

Further, for example, if it is desired to always receive the content having the priority level of 4 or more in the packet P8, if the content 12c having the priority 3 and the content 12d having the priority 4 are not correctly received, Then, a packet P10 may be generated by adding a header HD, a tailor TL, and a checksum CSh, CS3, CS4 to the contents 12c, 12d, and use this as a new packet to be retransmitted.

For example, if it is desired to always receive the content having the priority level 1 in the packet P8, and if the content 12a having the priority 1 is not correctly received, a header, a tailor,
A new packet to be retransmitted may be added with a checksum.

However, when it is inefficient to generate one packet with one or a small amount of content, for example, the content 12a may be mixed with a content group to be transmitted next and transmitted. In this case, the packet length control block 2 calls the contents 12 a from the transmission buffer memory 9 and sends them to the priority assignment block 3 together with the contents to be sent next. And
In the priority assignment block 3, the contents are rearranged and a level signal is assigned to each of them. For example,
A higher priority level signal may be given to the erroneous content 12a. Further, the priority of the erroneous content 12a may be lower than the priority of the newly transmitted content 12d.

Using the error control system in data transmission according to the present embodiment makes it possible to more reliably resend high-priority content in a packet.

As an example to which the error control system in data transmission according to the present embodiment can be applied, there is, for example, a net auction (auction using a communication line) other than the above-described remote monitoring system for crime prevention. When conducting an auction, the data sent by the buyer to the seller may be, for example, "buying" information, "successful bid price" information, "delivery place" information, and the like. Can be. Therefore, in this case, as in the case of the above-described security remote monitoring system, it is possible to reliably resend the content having a high priority in the packet.

Others. In Embodiments 1 and 2, ARQ
The error control system of the system is taken as an example.
Of course, the RQ method can be applied to the Stop-and-Wait method and also to the continuous ARQ method such as the Go-back-N method and the Selective-Repeat method. In either case,
If the information of the change in the packet length is transmitted to the receiving side at the time of retransmission, the protocol can be adapted between the transmitting station and the receiving station.

The present invention can be applied to any error control system other than the ARQ system, such as an information feedback system that notifies a transmitting station of a reception status.

[0086]

According to the present invention, if the error control system for data transmission according to the first aspect is used, the packet length can be reduced, so that the possibility of occurrence of errors is reduced and the transmission system in which the communication environment is not good. Even if there is, retransmission becomes more certain. Also, by increasing the packet length, it is possible to transmit more information at once.

According to the error control system for data transmission according to the second aspect of the present invention, the reception status is returned each time each packet is transmitted, so that the data to be communicated is more accurately transmitted to the receiving station. can do.

If the error control system for data transmission according to the third aspect of the present invention is used, when the receiving station has to terminate the reception for some reason, the content having the highest priority is transmitted to the receiving station. Can be transmitted.

With the error control system for data transmission according to the fourth aspect of the present invention, it is possible to more reliably retransmit contents having a high priority in a packet.

When the error control system for data transmission according to the fifth aspect of the present invention is used, it is necessary to quickly determine the presence or absence of an error or to roughly know where in a packet an error exists. Will be useful.

If the error control system in data transmission according to claim 6 of the present invention is used, not only the transmission history of a packet but also its contents can be stored for a long period of time. This can be used when the user wants to send a message or to certify the contents of the transmission.

According to the error control system for data transmission according to claim 7 of the present invention, the packet can be retransmitted when a predetermined time has elapsed after the transmission of the packet by the timer. In addition, the contents of the buffer memory can be erased when a certain time has elapsed after the transmission of the packet. Further, after the data is stored in the auxiliary storage device for a desired period, the data can be recalled and retransmitted.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an error control system in data transmission according to a first embodiment.

FIG. 2 is a diagram showing a structure of a packet used in an error control system in data transmission according to the first embodiment.

FIG. 3 is a block diagram showing an error control system in data transmission according to a second embodiment.

FIG. 4 is a diagram showing a structure of a packet used in an error control system in data transmission according to a second embodiment.

FIG. 5: Stop-and error control system of ARQ system
It is a figure which shows a -Wait method.

FIG. 6: Go-bac of the ARQ error control system
FIG. 3 is a diagram illustrating a kN scheme.

FIG. 7 is a diagram illustrating an ARQ-based error control system.
It is a figure showing an ive-Repeat system.

[Explanation of symbols]

1, 12a to 12d content, 2 packet length control block, 3 protocol conversion block, 4 transmission processing block, 5 reception processing block, 6 reception judgment block, 7 ACK / NAK signal reception block, 8 timer, 9 transmission buffer memory, 10 auxiliary storage devices,
11 Priority block

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 5K014 AA01 BA01 FA03 5K030 GA12 HA08 HB28 LA01 LA02 LA03 5K034 AA06 DD01 EE11 HH01 HH02 HH09 HH10 HH11 HH12 HH63 MM03 MM14 MM22 MM25 NN26

Claims (7)

[Claims] 1. A transmitting station for transmitting data in packet units, and a receiving station for receiving the data, wherein the transmitting station transmits the data to a packet length according to the success or failure of the data reception at the receiving station. Error control system in data transmission, changing and retransmitting. 2. The receiving station judges whether each packet of the data is successfully received, notifies the transmitting station of each judgment result, and the judgment result indicates that the reception of the packet is unsuccessful. 2. The error control system in data transmission according to claim 1, wherein when indicating, the transmitting station changes the packet length of the data by dividing the packet and generating a new packet. 3. The packet includes a plurality of contents, and priority information is given to each of the plurality of contents in accordance with a degree of necessity to reach the receiving station, and the plurality of contents are based on the priority. 3. An error control system in data transmission according to claim 2, wherein the contents are arranged. 4. The receiving station determines whether or not each of the plurality of contents has been successfully received, and transmits a result of the determination to the transmitting station by using the information on the priority of each of the plurality of contents. Notify, when the determination result indicates that reception of the content whose priority is equal to or more than a predetermined value is unsuccessful, the transmitting station,
The error control system in data transmission according to claim 3, wherein the packet length of the data is changed by selecting the content and generating a new packet. 5. The receiving station according to claim 1, wherein:
5. The error control system in data transmission according to claim 4, wherein success / failure of reception is determined even in a layer of a higher order than the plurality of contents. 6. The transmission station according to claim 1, further comprising: a buffer memory for temporarily storing the data; and an auxiliary storage device for storing the contents of the buffer memory in an overlapping manner. Error control system for data transmission in the Internet. 7. The error control system in data transmission according to claim 1, wherein the transmitting station further includes a timer for measuring an elapsed time from a transmission time point of each packet of the data.