Retransmission control device and retransmission control method

Abstract

This retransmission control device (100a) comprises: a bit error assessment unit (103a) for assessing the presence of a bit error in the data packet received by a reception unit (101) and detecting an error rate; a retransmission request unit (104) for transmitting a retransmission request to the sender of the data packet; a transmission unit (102) for transferring a data packet assessed as being free of bit errors to a subsequent processing unit; and a packet analysis unit (105) for instructing the retransmission request unit (104) to transmit a retransmission request when the error rate is greater than or equal to a retransmission threshold value, and instructing the transmission unit (102) to transfer a data packet assessed as having a bit error to the processing unit when the error rate is less than the retransmission threshold value.

Description

[Technical field]

[0001] The present invention relates to a retransmission control device and a retransmission control method for controlling the transmission and reception of data in a computer system such as an arithmetic unit. [Background technology]

[0002] Technological innovation is progressing in many fields such as machine learning, artificial intelligence (AI), and the Internet of Things (IoT), and by utilizing various information and data, services are being actively improved and added value is being provided. Processing in these fields requires large amounts of calculations, and therefore an information processing infrastructure is essential.

[0003] For example, Non-Patent Document 1 discloses an attempt to update the existing information processing infrastructure. However, it is also true that modern computer systems are unable to keep up with the rapidly increasing amount of data. Non-Patent Document 1 also points out that in order to achieve further evolution in the future, technology that surpasses Moore's Law must be established.

[0004] As a technology that goes beyond Moore's Law, for example, a technology called flow-centric computing is disclosed in Non-Patent Document 2. Flow-centric computing introduces a new concept of moving data to a location where a computing function is present and processing the data there, instead of the conventional computing approach of performing processing where the data is located.

[0005] To realize the above-mentioned flow-centric computing, a wideband communication network is necessary for data movement. At the same time, if the communication network is not controlled efficiently, data movement may not be performed efficiently.

[0006] Generally, as one of the processes that affect the efficiency of data transfer, retransmission processing when a packet error occurs can be cited. When a packet error occurs, the packet is retransmitted at a predetermined retransmission interval. However, since the desired arithmetic processing cannot be started until the retransmission of the packet is completed, the processing time is extended or the throughput deteriorates. As shown in Non-Patent Document 2, in a large-scale computer system that connects arithmetic units via an optical network, no example of an efficient retransmission control method has been disclosed.

Prior Art Documents

Non-Patent Documents

[0007]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] An object of the present invention is to provide a retransmission control device and a retransmission control method that can control the transmission and reception of data in a computer system and improve the performance of the entire system.

Means for Solving the Problems

[0009] A retransmission control device (first to fourth embodiments) of the present invention includes a receiving unit configured to receive a data packet, a bit error determination unit configured to determine the presence or absence of a bit error in the data packet received by the receiving unit and detect an error rate of the data packet determined to have a bit error, a retransmission request unit configured to transmit a retransmission request to a source of the data packet, a transmitting unit configured to transfer the data packet determined to have no bit error by the bit error determination unit to a downstream processing unit, and a packet analysis unit configured to instruct the retransmission request unit to transmit the retransmission request when the error rate is equal to or greater than a retransmission threshold, and to instruct the transmitting unit to transfer the data packet determined to have a bit error by the bit error determination unit to the processing unit when the error rate is smaller than the retransmission threshold. Before comparing the error rate with the retransmission threshold, the packet analysis unit analyzes the data packet determined to have a bit error by the bit error determination unit, thereby determining the processing content to be performed by the processing unit on the data packet, and sets the retransmission threshold corresponding to the processing content. It is characterized by the above.

[0010] In addition, in one configuration example (second embodiment) of the retransmission control device of the present invention, the packet analysis unit determines whether or not a bit error detected by the bit error determination unit when the error rate is smaller than the retransmission threshold is a bit error that will cause a significant difference in the calculation processing of the processing unit, and when it is determined that the bit error is a bit error that will cause a significant difference, it instructs the retransmission request unit to transmit the retransmission request, and when it is determined that the bit error is a bit error that will not cause a significant difference, it instructs the transmission unit to transfer the data packet that has been determined to have a bit error by the bit error determination unit to the processing unit. 。

[0011] Furthermore, one configuration example (fourth embodiment) of the retransmission control device of the present invention is characterized in that it further includes a first threshold setting unit configured to set the retransmission threshold corresponding to the sender of the data packet received by the receiving unit. Furthermore, one configuration example (fourth embodiment) of the retransmission control device of the present invention is characterized in that it further includes a second threshold setting unit configured to set the retransmission threshold corresponding to the processing unit. Furthermore, one configuration example (third embodiment) of the retransmission control device of the present invention is characterized in that it further includes a threshold change unit configured to change the retransmission threshold based on the quality of the processing result of the processing unit.

[0012] Moreover, a retransmission control method (first to fourth embodiments) of the present invention includes a first step of receiving a data packet, a second step of determining whether or not there is a bit error in the data packet received in the first step and detecting an error rate of the data packet determined to have a bit error, and a third step of transferring the data packet determined to have no bit error in the second step to a downstream processing unit. a fourth step of determining a process to be performed by the processing unit on the data packet determined to have a bit error by analyzing the data packet determined to have a bit error in the second step, and setting a retransmission threshold corresponding to the process; The error rate The above If the retransmission threshold is exceeded, a retransmission request is sent to the source of the data packet. 5 a third step of transferring the data packet determined to have a bit error in the second step to the processing unit when the error rate is smaller than the retransmission threshold value. 6 The present invention is characterized by including the steps of: Effect of the Invention

[0013] According to the present invention, the retransmission control device receives a data packet, judges whether or not there is a bit error in the received data packet, and detects the error rate of the data packet judged to have a bit error. Next, when the error rate of the data packet judged to have a bit error by the bit error judgment unit is equal to or greater than the retransmission threshold, the retransmission control device transmits a retransmission request to the sender of the data packet. Also, when the error rate is smaller than the retransmission threshold, the retransmission control device transfers the data packet to a processing unit at a subsequent stage. In the present invention, retransmission of data packets that are not originally necessary for providing the service quality required in the subsequent processing can be suppressed, and while providing the required service quality, an increase in processing time associated with retransmission can be suppressed, thereby realizing low delay. Also, in the present invention, the network load and power consumption associated with the transmission and reception of retransmission packets can be reduced. Furthermore, in the present invention, the buffer that temporarily stores data packets on the transmission side for the transmission of retransmission packets can be reduced. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a block diagram showing the configuration of a conventional retransmission control device. [Diagram 2] FIG. 2 is a block diagram showing a configuration of a retransmission control device according to a first embodiment of the present invention. [Diagram 3] FIG. 3 is a flowchart illustrating the operation of the retransmission control device according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a block diagram showing a configuration of a retransmission control device according to a second embodiment of the present invention. [Diagram 5] FIG. 5 is a flowchart illustrating the operation of the retransmission control device according to the second embodiment of the present invention. [Figure 6] FIG. 6 is a block diagram showing a configuration of a retransmission control device according to the third embodiment of the present invention. [Figure 7] FIG. 7 is a flowchart illustrating the operation of the retransmission control device according to the third embodiment of the present invention. [Figure 8]FIG. 8 is a block diagram showing a configuration of a retransmission control device according to the fourth embodiment of the present invention. [Figure 9] FIG. 9 is a block diagram showing a configuration of a computer system including a retransmission control device according to the fourth embodiment of the present invention. [Figure 10] FIG. 10 is a flowchart illustrating the operation of the retransmission control device according to the fourth embodiment of the present invention. [Figure 11] FIG. 11 is a block diagram showing an example of the configuration of a computer that realizes the retransmission control device according to the first to fourth embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] [Previous configuration] First, the configuration of a conventional retransmission control device will be described with reference to Fig. 1. The conventional retransmission control device 100 includes a receiving unit 101 that receives a data packet DP, a transmitting unit 102 that transfers the data packet DP to a downstream processing block or processing device, a bit error determining unit 103 that determines whether or not a bit error exists in the data packet DP received by the receiving unit 101, and a retransmission request unit 104 that outputs a retransmission request message RP (retransmission request packet) to the outside of the retransmission control device 100.

[0016] The transmitting unit 102 transfers the data packet DP that is determined to have no bit error by the bit error determining unit 103 to a downstream processing unit. If the bit error determining unit 103 determines that there is a bit error, the retransmission request unit 104 transmits a retransmission request message RP to the source of the data packet DP.

[0017] [Configuration of the first embodiment] Next, the configuration of a retransmission control device according to a first embodiment of the present invention will be described with reference to Fig. 2. The retransmission control device 100a of this embodiment includes a receiving unit 101 that receives a data packet DP, a transmitting unit 102 that transfers the data packet DP to a downstream processing block or processing device, a bit error determining unit 103a that determines whether or not there is a bit error in the data packet DP and detects an error rate indicating the proportion of data packets DP that are determined to have a bit error that contain bit errors, and a retransmission request unit 104 that transmits a retransmission request message RP (retransmission request packet) to the sender of the data packet DP.

[0018] The retransmission control device 100a also includes a packet analysis unit 105 that instructs the retransmission request unit 104 to send a retransmission request when the error rate is equal to or greater than the retransmission threshold TH, and instructs the transmission unit 102 to transfer the data packet determined to have a bit error by the bit error determination unit 103a to a downstream processing block or processing device when the error rate is smaller than the retransmission threshold TH.

[0019] More specifically, the packet analysis unit 105 analyzes the header or payload of the data packet DP that is determined to have a bit error by the bit error determination unit 103a, and thereby determines the processing or service content to be applied to the data packet DP by a subsequent processing block or processing device (processing unit). The packet analysis unit 105 sets a retransmission threshold TH corresponding to the processing or service content determined as a result of the analysis.

[0020] The packet analysis unit 105 compares the retransmission threshold TH with the error rate of the data packet DP detected by the bit error determination unit 103a, and if the error rate is equal to or greater than the retransmission threshold TH, sets a retransmission flag F. Also, if the error rate of the data packet DP is smaller than the retransmission threshold TH, the packet analysis unit 105 instructs the transmission unit 102 to transfer this data packet DP to a downstream processing unit. One example of the error rate is an error rate that indicates how many error bits are contained in the data packet DP.

[0021] The retransmission control device 100a of this embodiment differs from the conventional retransmission control device 100 in that it includes a packet analysis unit 105. Since the conventional retransmission control device 100 does not include the packet analysis unit 105, when the bit error determination unit 103 determines that there is a bit error, the retransmission flag F is set in the retransmission request unit 104 without analyzing the data packet DP. In other words, when the data packet DP includes a bit error, a retransmission request is made across the board regardless of the processing content or service content applied to the data packet DP by a processing unit at a later stage.

[0022] On the other hand, the retransmission control device 100a of this embodiment judges whether or not there is a bit error in the received data packet DP, and detects an error rate indicating how many bit errors are contained in the data packet DP. When the data packet DP contains a bit error, the retransmission control device 100a analyzes the header or payload of the data packet DP, and determines the processing content or service content to be applied to the data packet DP by a processing unit at a later stage.

[0023] The retransmission control device 100a sets a retransmission threshold TH corresponding to the processing content or service content determined as a result of the analysis. The retransmission control device 100a compares the retransmission threshold TH with the error rate, and if the error rate is equal to or greater than the retransmission threshold TH, transmits a retransmission request message RP to the outside of the retransmission control device 100a, and if the error rate is smaller than the retransmission threshold TH, transfers the data packet DP to a downstream processing unit.

[0024] As a result, in this embodiment, the necessity of retransmission can be changed depending on the processing contents and service contents in the subsequent stage. For example, in machine learning such as image recognition and object detection, even if an image or video to be recognized contains an error, the recognition accuracy may not be affected.

[0025] In the conventional retransmission control device 100, a retransmission request is made regardless of the processing content or service content in the subsequent stages, so that retransmission of a data packet DP increases the processing time required until recognition is completed.

[0026] On the other hand, in the retransmission control device 100a of this embodiment, even if the image or video to be recognized contains an error, as long as the error does not affect the recognition accuracy, retransmission is not required, thereby suppressing an increase in the processing time required to complete recognition.

[0027] [Operation of the first embodiment] Next, the operation of the retransmission control device 100a of this embodiment will be described with reference to Fig. 3. The retransmission control device 100a of this embodiment first receives a data packet DP, judges whether or not there is a bit error in the received data packet DP, and detects the error rate of the data packet DP. Next, if the error rate of the data packet DP judged by the bit error judgment unit 103a to have a bit error is equal to or greater than the retransmission threshold value TH, the retransmission control device 100a transmits a retransmission request message RP to the outside. Also, if the error rate is smaller than the retransmission threshold value TH, the retransmission control device 100a transfers the data packet DP to a processing unit at a subsequent stage.

[0028] First, the receiving unit 101 receives a data packet DP from a transmitting device via a communication network (step S100 in FIG. 3).

[0029] The bit error determining unit 103a determines whether or not there is a bit error in the data packet DP received by the receiving unit 101, and detects the error rate of the data packet DP if a bit error is included (step S101 in FIG. 3).

[0030] If the bit error determination unit 103a determines that there is no bit error (NO in step S101), the transmission unit 102 transfers the data packet DP to a downstream processing unit (step S102 in FIG. 3). The processing unit processes the data packet DP transferred from the retransmission control device 100a.

[0031] Next, if the bit error determination unit 103a determines that there is a bit error (YES in step S101), the packet analysis unit 105 analyzes the header or payload of the data packet DP to determine the processing content or service content to be applied to the data packet DP by a downstream processing unit (step S103 in Figure 3).

[0032] The packet analysis unit 105 sets a retransmission threshold TH corresponding to the processing content or service content identified as a result of the analysis (step S104 in FIG. 3), and compares the retransmission threshold TH with the error rate detected by the bit error determination unit 103a (step S105 in FIG. 3).

[0033] The packet analysis unit 105 stores in advance a table in which the relationship between the processing content or service content for the data packet DP and the retransmission threshold value TH to be set is registered. The packet analysis unit 105 acquires the retransmission threshold value TH corresponding to the processing content or service content identified as a result of the analysis from the table.

[0034] If the error rate is equal to or greater than the retransmission threshold TH (YES in step S105), the packet analysis unit 105 sets the retransmission flag F (step S106 in FIG. 3). By setting the retransmission flag F, it is possible to instruct the retransmission request unit 104 to transmit a retransmission request.

[0035] Furthermore, if the error rate is smaller than the retransmission threshold TH (NO in step S105), the packet analysis unit 105 instructs the transmission unit 102 to transfer the data packet DP to a downstream processing unit (step S107 in FIG. 3).

[0036] When the retransmission flag F is set by the packet analysis unit 105, the retransmission request unit 104 transmits a retransmission request message RP (retransmission request packet) to the source of the data packet DP (step S108 in FIG. 3).

[0037] When receiving a transfer instruction from the packet analysis unit 105, the transmission unit 102 transfers the data packet DP to a downstream processing unit (step S102).

[0038] [Effects of the first embodiment] As described above, the retransmission control device 100a of this embodiment judges whether or not there is a bit error in the received data packet DP, and detects the error rate of the data packet DP. Next, the retransmission control device 100a analyzes the header or payload of the data packet DP that the bit error judgment unit 103a judges to have a bit error, and determines the processing content or service content to be applied to the data packet DP by the subsequent processing unit. The retransmission control device 100a sets a retransmission threshold TH corresponding to the processing content or service content identified as a result of the analysis.

[0039] When the error rate of the data packet DP that the bit error determination unit 103a has determined to have a bit error is equal to or greater than the retransmission threshold TH, the retransmission control device 100a transmits a retransmission request message RP to the source of the data packet DP. When the error rate is smaller than the retransmission threshold TH, the retransmission control device 100a transfers the data packet DP to a downstream processing unit.

[0040] In this embodiment, retransmission of data packets DP that are not necessary for providing the service quality required in the subsequent processing can be suppressed, and the required service quality can be provided while suppressing an increase in processing time associated with retransmission, thereby realizing low latency. In this embodiment, the network load and power consumption associated with the transmission and reception of retransmission packets can be reduced. Furthermore, in this embodiment, the buffer that temporarily stores data packets DP on the transmission side for the transmission of retransmission packets can be reduced.

[0041] [Configuration of the second embodiment] Next, a second embodiment of the present invention will be described. Fig. 4 is a block diagram showing the configuration of a retransmission control device according to the second embodiment of the present invention. The retransmission control device 100b of this embodiment includes a receiving unit 101 for receiving a data packet DP, a transmitting unit 102 for transferring the data packet DP to a processing unit at a subsequent stage, a bit error determining unit 103a for determining the presence or absence of a bit error in the data packet DP and detecting the error rate of the data packet DP determined to have a bit error, and a retransmission request unit 104 for transmitting a retransmission request message RP to the sender of the data packet DP.

[0042] The retransmission control device 100b also includes a packet analysis unit 105b that instructs the retransmission request unit 104 to send a retransmission request when the error rate is equal to or higher than the retransmission threshold TH, and determines whether the bit error detected by the bit error judgment unit 103a when the error rate is lower than the retransmission threshold TH is a bit error that will cause a significant difference in the calculation processing of a downstream processing unit, and if it is determined that the bit error will cause a significant difference, instructs the retransmission request unit 104 to send a retransmission request, and if it is determined that the bit error will not cause a significant difference, instructs the transmission unit 102 to transfer the data packet determined by the bit error judgment unit 103a to have a bit error to the downstream processing unit.

[0043] More specifically, the packet analysis unit 105b analyzes the header or payload of the data packet DP that is determined to have a bit error by the bit error determination unit 103a, and determines the processing or service content to be applied to the data packet DP by a subsequent processing unit. The packet analysis unit 105b sets a retransmission threshold TH corresponding to the processing or service content determined as a result of the analysis.

[0044] The packet analysis unit 105b compares the retransmission threshold TH with the error rate of the data packet DP detected by the bit error determination unit 103a, and sets a retransmission flag F if the error rate is equal to or greater than the retransmission threshold TH.

[0045] In addition, the packet analysis unit 105b includes an error-mixed location identification unit 106 that identifies the location where the bit error detected by the bit error determination unit 103a has occurred for each chunk of data of a predetermined size contained in the data packet DP when the error rate of the data packet DP is smaller than the retransmission threshold TH.

[0046] The packet analysis unit 105b determines, based on the result of identification by the error-mixed portion identification unit 106, whether or not the bit error detected by the bit error determination unit 103a is a bit error that will cause a significant difference in the arithmetic processing of a subsequent processing unit.

[0047] If the packet analysis unit 105b determines that the bit error is one that causes a significant difference, it sets a retransmission flag F. If the packet analysis unit 105b determines that the bit error is one that does not cause a significant difference, it instructs the transmission unit 102 to transfer the data packet DP to a downstream processing unit.

[0048] In addition, when a downstream processing unit performs image recognition, for example, the error-mixed location identification unit 106 identifies whether the bit error has occurred in a location that does not affect the results of image recognition (for example, the background part of the image) or a location that does affect the results of image recognition (for example, near the center of the image).

[0049] [Operation of the second embodiment] Next, the operation of the retransmission control device 100b of this embodiment will be described with reference to Fig. 5. The retransmission control device 100b of this embodiment first receives a data packet DP, judges whether or not there is a bit error in the received data packet DP, and detects the error rate of the data packet DP. Next, if the error rate of the data packet DP that the bit error judgment unit 103a judges to have a bit error is equal to or greater than the retransmission threshold value TH, the retransmission control device 100b transmits a retransmission request message RP to the outside.

[0050] If the error rate is smaller than the retransmission threshold TH, the retransmission control device 100b determines whether or not the bit error will cause a significant difference in the arithmetic processing of the downstream processing unit, and if the bit error causes a significant difference, sets the retransmission flag F. Also, if the bit error does not cause a significant difference, the retransmission control device 100b transfers the data packet DP to the downstream processing unit.

[0051] First, the receiving unit 101 receives a data packet DP from a transmitting device via a communication network (FIG. 5, step S200).

[0052] The bit error determining unit 103a determines whether or not there is a bit error in the data packet DP received by the receiving unit 101, and detects the error rate of the data packet DP if a bit error is included (step S201 in FIG. 5).

[0053] If the bit error determining section 103a determines that there is no bit error (NO in step S201), the transmitting section 102 transfers the data packet DP to a downstream processing section (step S202 in FIG. 5).

[0054] Next, if the bit error determination unit 103a determines that there is a bit error (YES in step S201), the packet analysis unit 105b analyzes the header or payload of the data packet DP to determine the processing content or service content to be applied to the data packet DP by a downstream processing unit (step S203 in FIG. 5).

[0055] The packet analysis unit 105b sets a retransmission threshold TH corresponding to the processing content or service content identified as a result of the analysis (step S204 in FIG. 5), and compares the retransmission threshold TH with the error rate detected by the bit error determination unit 103a (step S205 in FIG. 5).

[0056] The packet analysis unit 105b stores in advance a table in which the relationship between the processing content or service content for the data packet DP and the retransmission threshold value TH to be set is registered. The packet analysis unit 105b acquires the retransmission threshold value TH corresponding to the processing content or service content identified as a result of the analysis from the table. If the error rate is equal to or greater than the retransmission threshold TH (YES in step S205), the packet analysis unit 105b sets the retransmission flag F (step S206 in FIG. 5).

[0057] If the error rate is smaller than the retransmission threshold TH (NO in step S205), the packet analysis unit 105b judges whether or not the bit error will cause a significant difference in the calculation process of the subsequent processing unit. Specifically, the error-mixed portion identification unit 106 identifies the portion where the bit error detected by the bit error determination unit 103a occurs for each chunk of data of a predetermined size contained in the data packet DP received by the receiving unit 101 (step S207 in FIG. 5).

[0058] Then, the packet analysis unit 105b determines, based on the result of identification by the error-mixed portion identification unit 106, whether or not the bit error detected by the bit error determination unit 103a is a bit error that will cause a significant difference in the processing of a subsequent processing unit (FIG. 5, step S208).

[0059] When image processing is performed in a downstream processing section, a chunk of data of a predetermined size refers to data for one image, for example. For example, if a bit error occurs in a predetermined important location in the data for one image contained in a data packet DP received by the receiving unit 101, the packet analysis unit 105b determines that there is a fatal error, and determines that the bit error will cause a significant difference in the calculation processing of a downstream processing unit.

[0060] Alternatively, the packet analysis unit 105b may determine that a bit error occurs when the rate at which bit errors occur in data for one image exceeds a predetermined rate, as a bit error that causes a significant difference.

[0061] If the packet analysis unit 105b determines that the bit error is one that will cause a significant difference (YES in step S208), it sets the retransmission flag F (FIG. 5, step S206). If the packet analysis unit 105b determines that the bit error is one that will not cause a significant difference (NO in step S208), it instructs the transmission unit 102 to transfer the data packet DP to a downstream processing unit (FIG. 5, step S209).

[0062] When the retransmission flag F is set by the packet analysis unit 105b, the retransmission request unit 104 transmits a retransmission request message RP (retransmission request packet) to the source of the data packet DP (step S210 in FIG. 5).

[0063] When receiving a transfer instruction from the packet analysis unit 105b, the transmission unit 102 transfers the data packet DP to a downstream processing unit (step S202).

[0064] [Effects of the second embodiment] As described above, the retransmission control device 100b of this embodiment judges whether or not there is a bit error in the received data packet DP, and detects the error rate of the data packet DP. Next, the retransmission control device 100b analyzes the header or payload of the data packet DP that the bit error judgment unit 103a judges to have a bit error, and determines the processing content or service content to be applied to the data packet DP by the subsequent processing unit. The retransmission control device 100b sets a retransmission threshold TH corresponding to the processing content or service content identified as a result of the analysis.

[0065] If the error rate of the data packet DP that the bit error determination unit 103a has determined to have a bit error is equal to or greater than the retransmission threshold TH, the retransmission control device 100b transmits a retransmission request message RP to the source of the data packet DP. If the error rate is smaller than the retransmission threshold TH, the retransmission control device 100b determines whether or not the bit error will cause a significant difference in the arithmetic processing of the downstream processing unit, and if the bit error causes a significant difference, sets a retransmission flag F. If the bit error does not cause a significant difference, the retransmission control device 100b transfers the data packet DP to the downstream processing unit.

[0066] In this embodiment, retransmission of data packets DP that are not necessary for providing the service quality required in the subsequent processing can be suppressed, and the increase in processing time associated with retransmission can be suppressed while providing the required service quality, thereby realizing low latency. In this embodiment, the network load and power consumption associated with the transmission and reception of retransmission packets can be reduced. In addition, in this embodiment, the buffer that temporarily stores data packets DP on the transmission side for the transmission of retransmission packets can be reduced.

[0067] In the first embodiment, increasing the retransmission threshold TH reduces the frequency of retransmission, thereby enhancing the effect of reducing latency, but at the same time, the quality of processing in the downstream processing unit may be reduced. On the other hand, in this embodiment, by determining whether or not a bit error occurs that will cause a significant difference in the processing in the downstream processing unit, it is possible to increase the retransmission threshold TH to enhance the effect of reducing latency, while at the same time suppressing the degradation of the quality of processing in the downstream processing unit.

[0068] [Configuration of the third embodiment] Next, a third embodiment of the present invention will be described. Fig. 6 is a block diagram showing the configuration of a retransmission control device according to the third embodiment of the present invention. The retransmission control device 100c of this embodiment includes a receiving unit 101 for receiving a data packet DP, a transmitting unit 102 for transferring the data packet DP to a processing unit at a subsequent stage, a bit error determining unit 103a for determining the presence or absence of a bit error in the data packet DP and detecting the error rate of the data packet DP determined to have a bit error, and a retransmission request unit 104 for transmitting a retransmission request message RP (retransmission request packet) to the sender of the data packet DP.

[0069] The retransmission control device 100c also includes a packet analysis unit 105 that instructs the retransmission request unit 104 to send a retransmission request when the error rate is equal to or greater than the retransmission threshold TH, and instructs the transmission unit 102 to transfer the data packet determined to have a bit error by the bit error determination unit 103a to a downstream processing block or processing device when the error rate is smaller than the retransmission threshold TH, and a threshold change unit 107 that dynamically changes the retransmission threshold TH based on the quality of the processing result of the downstream processing unit.

[0070] More specifically, when the quality of the processing result of the downstream processing unit remains better than the reference value for a predetermined period of time or more, the threshold change unit 107 controls the retransmission frequency of the data packet DP to be reduced by increasing the retransmission threshold TH by a predetermined amount from the current value. Also, when the frequency at which the quality of the processing result of the downstream processing unit deteriorates below the reference value becomes higher than a predetermined value, the threshold change unit 107 controls the retransmission frequency to be increased by decreasing the retransmission threshold TH by a predetermined amount from the current value.

[0071] The quality of the processing result of the latter processing unit refers to the recognition accuracy, for example, when the latter processing unit performs image recognition. The threshold change unit 107 increases the retransmission threshold TH when the recognition accuracy is equal to or higher than the reference value for a predetermined period of time or more. In addition, the threshold change unit 107 decreases the retransmission threshold TH when the frequency at which the recognition accuracy is degraded from the reference value becomes higher than a predetermined value.

[0072] In the above example, the threshold change unit 107 judges whether the processing result of the downstream processing unit is good or bad, but it is not necessary to provide the threshold change unit 107 with a function for judging whether the processing result is good or bad. For example, the downstream processing unit may judge whether the processing result is good or bad. The threshold change unit 107 dynamically changes the retransmission threshold TH by referring to the judgment result.

[0073] Alternatively, the client device may use the processing result of the subsequent processing unit to determine whether the processing result is acceptable. The threshold change unit 107 dynamically changes the retransmission threshold TH by acquiring the determination result by the client device.

[0074] [Operation of the third embodiment] Next, the operation of the retransmission control device 100c of this embodiment will be described with reference to Fig. 7. The retransmission control device 100c of this embodiment first receives a data packet DP, judges whether or not there is a bit error in the received data packet DP, and detects the error rate of the data packet DP. If the error rate of the data packet DP judged by the bit error judgment unit 103a to have a bit error is equal to or greater than the retransmission threshold TH, the retransmission control device 100c transmits a retransmission request message RP to the outside. If the error rate is smaller than the retransmission threshold TH, the retransmission control device 100c transfers the data packet DP to a processing unit at a subsequent stage. Furthermore, the retransmission control device 100c changes the retransmission threshold TH based on the quality of the processing result of the processing unit at the subsequent stage.

[0075] First, the receiving unit 101 receives a data packet DP from a transmitting device via a communication network (step S300 in FIG. 7).

[0076] The bit error determining unit 103a determines whether or not there is a bit error in the data packet DP received by the receiving unit 101, and detects the error rate of the data packet DP if a bit error is included (Step S301 in FIG. 7).

[0077] If the bit error determining section 103a determines that there is no bit error (NO in step S301), the transmitting section 102 transfers the data packet DP to a downstream processing section (step S302 in FIG. 7).

[0078] Next, if the bit error determination unit 103a determines that there is a bit error (YES in step S301), the packet analysis unit 105 analyzes the header or payload of the data packet DP to determine the processing content or service content to be applied to the data packet DP by a downstream processing unit (step S303 in FIG. 7).

[0079] The packet analysis unit 105 sets a retransmission threshold TH corresponding to the processing content or service content identified as a result of the analysis (step S304 in FIG. 7), and compares the retransmission threshold TH with the error rate detected by the bit error determination unit 103a (step S305 in FIG. 7).

[0080] If the error rate is equal to or greater than the retransmission threshold TH (YES in step S305), the packet analysis unit 105 sets the retransmission flag F (step S306 in FIG. 7). If the error rate is smaller than the retransmission threshold TH (NO in step S305), the packet analysis unit 105 instructs the transmission unit 102 to transfer the data packet DP to a downstream processing unit (step S307 in FIG. 7).

[0081] When the retransmission flag F is set by the packet analysis unit 105, the retransmission request unit 104 transmits a retransmission request message RP (retransmission request packet) to the source of the data packet DP (step S308 in FIG. 7).

[0082] When receiving a transfer instruction from the packet analysis unit 105, the transmission unit 102 transfers the data packet DP to a downstream processing unit (step S302).

[0083] On the other hand, the threshold change unit 107 monitors the quality of the processing result of the subsequent processing unit (step S309 in FIG. 7). If the quality of the processing result of the subsequent processing unit remains better than the reference value for a predetermined period of time or more (YES in step S310 in FIG. 7), the threshold change unit 107 increases the retransmission threshold TH by a predetermined amount from the current value (step S311 in FIG. 7).

[0084] In addition, if the frequency at which the quality of the processing result of the subsequent processing unit deteriorates below the reference value becomes higher than a predetermined value (YES in step S310), the threshold change unit 107 lowers the retransmission threshold TH by a predetermined amount from the current value (step S311).

[0085] [Effects of the third embodiment] As described above, the retransmission control device 100c of this embodiment judges whether or not there is a bit error in the received data packet DP, and detects the error rate of the data packet DP. Next, the retransmission control device 100c analyzes the header or payload of the data packet DP that the bit error judgment unit 103a judges to have a bit error, and determines the processing content or service content to be applied to the data packet DP by the subsequent processing unit. The retransmission control device 100c sets a retransmission threshold TH corresponding to the processing content or service content identified as a result of the analysis.

[0086] If the error rate of the data packet DP that the bit error determination unit 103a has determined to have a bit error is equal to or greater than the retransmission threshold TH, the retransmission control device 100c transmits a retransmission request message RP to the source of the data packet DP. If the error rate is smaller than the retransmission threshold TH, the retransmission control device 100c transfers the data packet DP to a downstream processing unit. Furthermore, the retransmission control device 100c changes the retransmission threshold TH based on the quality of the processing result of the downstream processing unit.

[0087] In this embodiment, retransmission of data packets DP that are not necessary for providing the service quality required in the subsequent processing can be suppressed, and the increase in processing time associated with retransmission can be suppressed while providing the required service quality, thereby realizing low latency. In this embodiment, the network load and power consumption associated with the transmission and reception of retransmission packets can be reduced. In addition, in this embodiment, the buffer that temporarily stores data packets DP on the transmission side for the transmission of retransmission packets can be reduced.

[0088] Furthermore, in this embodiment, by changing the retransmission threshold TH based on the quality of the processing result of the subsequent processing unit, when the quality of the processing result is good, retransmission can be suppressed more actively. As a result, in this embodiment, the effect of reducing delay can be further enhanced compared to the first embodiment, and the network load and power consumption can be further reduced.

[0089] In this embodiment, the threshold change unit 107 is applied to the first embodiment, but the second embodiment and this embodiment may be combined.

[0090] [Configuration of the fourth embodiment] Next, a fourth embodiment of the present invention will be described. Fig. 8 is a block diagram showing the configuration of a retransmission control device according to the fourth embodiment of the present invention. Fig. 9 is a block diagram showing the configuration of a computer system including a retransmission control device according to the fourth embodiment of the invention.

[0091] The retransmission control device 100d of this embodiment includes a receiving unit 101 that receives a data packet DP, a transmitting unit 102 that transfers the data packet DP to a downstream processing block or processing device, a bit error determination unit 103a that determines whether or not there is a bit error in the data packet DP and detects an error rate indicating the proportion of data packets DP that are determined to have a bit error that contain bit errors, and a retransmission request unit 104 that transmits a retransmission request message RP (retransmission request packet) to the sender of the data packet DP.

[0092] The retransmission control device 100d also includes a packet analysis unit 105 that instructs the retransmission request unit 104 to send a retransmission request when the error rate is equal to or greater than the retransmission threshold TH, and instructs the transmission unit 102 to transfer data packets determined to have a bit error by the bit error determination unit 103a to a downstream processing block or processing device when the error rate is smaller than the retransmission threshold TH, a threshold setting unit 108 that sets the retransmission threshold TH for each downstream processing unit, and a threshold setting unit 109 that sets the retransmission threshold TH for each client device that uses the processing results of the downstream processing unit.

[0093] The computer system includes client devices 1-1 to 1-M (M is an integer equal to or greater than 1) that request information processing such as arithmetic processing and image recognition to a server device via a communication network, server devices 2-1 to 2-N (N is an integer equal to or greater than 1) that perform information processing such as arithmetic processing and image recognition based on requests from the client devices 1-1 to 1-M, and a gateway 3 that relays communications between the client devices 1-1 to 1-M and the server devices 2-1 to 2-N. A retransmission control device 100d is provided in the gateway 3. The server devices 2-1 to 2-N are processing units subsequent to the retransmission control device 100d.

[0094] [Operation of the fourth embodiment] Next, the operation of the retransmission control device 100d of this embodiment will be described with reference to Fig. 10. The receiving unit 101 receives data packets DP from the transmitting client devices 1-1 to 1-M via the communication network 4 (Fig. 10, step S400).

[0095] The bit error determining unit 103a determines whether or not there is a bit error in the data packet DP received by the receiving unit 101, and detects the error rate of the data packet DP if a bit error is included (Step S401 in FIG. 10).

[0096] If the bit error determining section 103a determines that there is no bit error (NO in step S401), the transmitting section 102 transfers the data packet DP to the destination server device 2-1 to 2-N via the communication network 5 (step S402 in FIG. 10).

[0097] Next, if the bit error determination unit 103a determines that there is a bit error (YES in step S401), the packet analysis unit 105 analyzes the header or payload of the data packet DP to determine the processing content or service content that the server device 2-1 to 2-N, which is the destination of the data packet DP, will apply to the data packet DP (FIG. 10, step S403).

[0098] The packet analysis unit 105 sets a retransmission threshold TH corresponding to the processing content or service content identified as a result of the analysis (step S404 in FIG. 10). Here, similar to the first to third embodiments, the retransmission threshold TH corresponding to the processing content or service content is set, but the method of setting the retransmission threshold TH is not limited to this.

[0099] For example, the threshold setting unit 108 may set a retransmission threshold TH for each of the subsequent processing units (for each of the server devices 2-1 to 2-N that are destinations of the data packets DP) (step S404). Also, the threshold setting unit 109 may set a retransmission threshold TH for each of the client devices 1-1 to 1-M that use the processing results of the subsequent processing units (for each of the client devices 1-1 to 1-M that are source devices of the data packets DP) (step S404).

[0100] Retransmission criteria A1 to A between the gateway 3 and the client devices 1-1 to 1-M M and retransmission criteria B1 to B2 between the gateway 3 and the servers 2-1 to 2-N. Nand may be set independently. For example, the communication network 4 connecting the gateway 3 and the client devices 1-1 to 1-M is a long-distance network with unknown communication quality, such as a wireless communication network or the Internet. In contrast, the communication network 5 connecting the gateway 3 and the server devices 2-1 to 2-N is a short-distance network with relatively guaranteed communication quality, such as a wired communication network in a data center.

[0101] In such a network environment, retransmission criteria A1 to A2 between the gateway 3 and the client devices 1-1 to 1-M are M and retransmission criteria B1 to B2 between the gateway 3 and the servers 2-1 to 2-N. N In other words, the retransmission threshold TH set by the threshold setting unit 108 and the threshold setting unit 109 is a combination of these retransmission criteria A1 to A M ,B1~B N It is predetermined according to

[0102] In this embodiment, the retransmission threshold TH can be appropriately set by one or more of the following methods: setting of the retransmission threshold TH by the packet analysis unit 105, setting of the retransmission threshold TH by the threshold setting unit 108, and setting of the retransmission threshold TH by the threshold setting unit 109. However, when setting the retransmission threshold TH by two or more methods, it is desirable to determine the priority of each setting method in advance.

[0103] Next, the packet analysis unit 105 compares the retransmission threshold TH with the error rate detected by the bit error determination unit 103a (step S405 in FIG. 10). If the error rate is equal to or greater than the retransmission threshold TH (YES in step S405), the packet analysis unit 105 sets the retransmission flag F (step S406 in FIG. 10). By setting the retransmission flag F, it is possible to instruct the retransmission request unit 104 to transmit a retransmission request.

[0104] Furthermore, if the error rate is smaller than the retransmission threshold TH (NO in step S405), the packet analysis unit 105 instructs the transmission unit 102 to transfer the data packet DP to a downstream processing unit (step S407 in FIG. 10).

[0105] When the retransmission flag F is set by the packet analysis unit 105, the retransmission request unit 104 transmits a retransmission request message RP (retransmission request packet) to the client devices 1-1 to 1-M that are the senders of the data packets DP via the communications network 4 (step S408 in FIG. 10).

[0106] When receiving a transfer instruction from the packet analysis unit 105, the transmission unit 102 transfers the data packet DP to the destination server device 2-1 to 2-N via the communication network 5 (step S402).

[0107] When the transfer and processing of the data packet DP is repeated, such as when a desired process is divided into multiple steps between the gateway 3 and the server devices 2-1 to 2-N, errors may accumulate stepwise even if the error rate is below the retransmission threshold TH at the start of the process. In this case, a retransmission request is made to the client devices 1-1 to 1-M when the error rate reaches or exceeds the retransmission threshold TH.

[0108] Even if the data packet DP contains a bit error, the server devices 2-1 to 2-N can start processing, and during that processing, a retransmission request can be made to the client devices 1-1 to 1-M, and the data packet DP can be replaced at the point in time when the retransmission packet is received. By overlapping the processing in the server devices 2-1 to 2-N with the retransmission control, an increase in processing time due to the retransmission control can be suppressed.

[0109] [Effects of the fourth embodiment] As described above, the retransmission control device 100d of this embodiment judges whether or not there is a bit error in the received data packet DP, and detects the error rate of the data packet DP. Next, the retransmission control device 100d analyzes the header or payload of the data packet DP that the bit error judgment unit 103a judges to have a bit error, and determines the processing content or service content to be applied to the data packet DP by the subsequent processing unit. The retransmission control device 100d sets a retransmission threshold TH corresponding to the processing content or service content identified as a result of the analysis, a retransmission threshold TH corresponding to the subsequent processing unit, and a retransmission threshold TH corresponding to the client device that is the sender of the data packet DP.

[0110] The retransmission control device 100d transmits a retransmission request message RP to the source of the data packet DP when the error rate of the data packet DP determined by the bit error determination unit 103a to have a bit error is equal to or greater than the retransmission threshold TH. Also, when the error rate is smaller than the retransmission threshold TH, the retransmission control device 100a transfers the data packet DP to a downstream processing unit.

[0111] In this embodiment, retransmission of data packets DP that are not necessary for providing the service quality required in the subsequent processing can be suppressed, and the increase in processing time associated with retransmission can be suppressed while providing the required service quality, thereby realizing low latency. In this embodiment, the network load and power consumption associated with the transmission and reception of retransmission packets can be reduced. In addition, in this embodiment, the buffer that temporarily stores data packets DP on the transmission side for the transmission of retransmission packets can be reduced.

[0112] Furthermore, in this embodiment, by setting a retransmission threshold TH for each sender of the data packet DP, for each subsequent processing unit, and for each processing content in the subsequent processing unit, it is possible to provide different service qualities for each processing content or service content even if the processing request is from the same client device 1-1 to 1-M.

[0113] In this embodiment, the threshold setting units 108 and 109 are applied to the first embodiment, but the second embodiment and this embodiment may be combined. Moreover, it goes without saying that the configuration of FIG. 9 may be applied to the retransmission control devices 100a, 100b, and 100c of the first to third embodiments, and the gateway 3 may be provided with the retransmission control devices 100a, 100b, and 100c.

[0114] [Extended Example] Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention. In addition, the embodiments can be combined in any manner within a range that does not contradict each other.

[0115] The retransmission control devices 100a, 100b, 100c, and 100d described in the first to fourth embodiments can be realized by a computer equipped with a CPU (Central Processing Unit), a storage device, and an interface, and a program that controls these hardware resources. An example of the configuration of this computer is shown in Fig. 11. The computer is equipped with a CPU 200, a storage device 201, and an interface device (I / F) 202.

[0116] A communication network or the like is connected to the I / F 202. In such a computer, a program for implementing the retransmission control method of the present invention is stored in the storage device 201. The CPU 200 executes the processes described in the first to fourth embodiments according to the program stored in the storage device 201.

[0117] Each of the client devices 1-1 to 1-M and the server devices 2-1 to 2-N can also be realized by a computer. [Industrial Applicability]

[0118] The present invention can be applied to a computer system. [Explanation of symbols]

[0119] 1-1 to 1-M... client devices, 2-1 to 2-N... server devices, 3... gateways, 4, 5... communication networks, 100a, 100b, 100c, 100d... retransmission control devices, 101... receiving unit, 102... transmitting unit, 103a... bit error determination unit, 104... retransmission request unit, 105, 105b... packet analysis unit, 106... error contamination location identification unit, 107... threshold change unit, 108, 109... threshold setting units.

Claims

1. a receiver configured to receive data packets; a bit error determination unit configured to determine the presence or absence of a bit error in the data packet received by the receiving unit and to detect an error rate of the data packet determined to have a bit error; a retransmission request unit configured to send a retransmission request to a source of the data packet; a transmission unit configured to transfer the data packet determined to have no bit error by the bit error determination unit to a downstream processing unit; a packet analysis unit configured to instruct the retransmission request unit to transmit the retransmission request when the error rate is equal to or greater than a retransmission threshold, and to instruct the transmission unit to transfer a data packet determined to have a bit error by the bit error determination unit to the processing unit when the error rate is smaller than the retransmission threshold, A retransmission control device characterized in that the packet analysis unit analyzes a data packet that has been determined to have a bit error by the bit error determination unit before comparing the error rate with the retransmission threshold, thereby determining the processing content to be performed by the processing unit on the data packet, and setting the retransmission threshold corresponding to the processing content.

2. 2. The retransmission control device according to claim 1, The retransmission control device is characterized in that when the error rate is smaller than the retransmission threshold, the packet analysis unit determines whether or not the bit error detected by the bit error determination unit is a bit error that will cause a significant difference in the calculation processing of the processing unit, and if it determines that the bit error will cause a significant difference, it instructs the retransmission request unit to send the retransmission request, and if it determines that the bit error will not cause a significant difference, it instructs the transmission unit to transfer the data packet that has been determined to have a bit error by the bit error determination unit to the processing unit.

3. 3. The retransmission control device according to claim 1, 13. The retransmission control device, further comprising: a first threshold setting unit configured to set the retransmission threshold corresponding to a source of a data packet received by the receiving unit.

4. 4. The retransmission control device according to claim 1, The retransmission control device further comprising a second threshold setting unit configured to set the retransmission threshold corresponding to the processing unit.

5. 5. The retransmission control device according to claim 1, The retransmission control device further comprising a threshold change unit configured to change the retransmission threshold based on a quality of a processing result of the processing unit.

6. A first step of receiving a data packet; a second step of determining whether or not a bit error exists in the data packet received in the first step, and detecting an error rate of the data packet determined to have a bit error; a third step of transferring the data packet determined to have no bit error in the second step to a downstream processing unit; a fourth step of determining a process to be performed by the processing unit on the data packet determined to have a bit error by analyzing the data packet determined to have a bit error in the second step, and setting a retransmission threshold corresponding to the process; a fifth step of sending a retransmission request to a source of the data packet if the error rate is greater than or equal to the retransmission threshold; and a sixth step of transferring the data packet determined to have a bit error in the second step to the processing unit when the error rate is smaller than the retransmission threshold.

Images