JP5524889B2 - MONITORING SYSTEM, NETWORK DEVICE, AND COMMUNICATION CONTROL METHOD - Google Patents

Description

  The present invention relates to a monitoring system, a network device, and a communication control method.

In recent years, there has been a growing demand for remote monitoring and maintenance of equipment such as boilers and thermal turbines and monitoring of energy consumption from a management center located far from the site where the equipment is installed. Ideally, all the data of sensors and surveillance cameras installed at the end of such a monitoring system should be centralized and managed at the center. However, as the number of sensors and cameras has increased, it has become difficult to always collect all data to the center due to the traffic capacity that can be transmitted over the network.
In order to cope with such a current situation, for example, Patent Document 1 discloses a technique for controlling the priority of transfer / display of image data from a camera.

Furthermore, it is expected that wireless public networks such as mobile phones will be used in the network connecting the field and the management center. For example,
1) If the equipment to be monitored is a moving object such as a car or railway,
2) When a large number of communication terminals are installed in a wide range, such as automatic meter reading of electric meters, and 3) When the network configuration changes drastically, such as when communication terminals are added in stages or the installation location is changed frequently. The reason for this is that wireless connection is easy and easy to connect even when wired connection is difficult or when the efficiency is low and the wiring cost is high.

JP 2009-171471 A

  When wireless is used for the network connecting the site and the management center, the bandwidth fluctuation is larger than that in the case of wired communication, so even a packet transmitted with priority may be lost during transmission. To cope with such packet loss, not only priority control but also a retransmission mechanism is required in which the same packet is sent again when the sent packet does not arrive.

  As shown in FIG. 10, in order to implement the retransmission function, a case where a communication protocol 121 with a retransmission function (for example, TCP) is used for communication between the network interconnection device 111 and the management center 113 is considered. In this configuration, after the packet transmission order is determined by the priority control function 122, the retransmission control information 123 is exchanged between the communication protocols 121 to perform retransmission control. As shown in FIG. 8, when the wide area network condition suddenly deteriorates while the low-priority packet 81 is transmitted (82), the communication protocol resends the low-priority packet many times (83), and the result As a result, the high-priority packet 84 cannot be transmitted, and the transmission delay of a high-priority packet that should be sent quickly may increase. In other words, since priority control and retransmission control are not linked, there is a risk that contradictory control is performed and the expected performance cannot be obtained.

  In addition, in a system that transmits data measured by various sensors and cameras to the management center, whether it is better to send the latest data first or in order from the past data depends on the contents and characteristics of the sensor data. Dependent. Therefore, a system that can flexibly set priority according to the type of sensor data is required.

  In view of the above points, an object of the present invention is to provide a monitoring system and a network device that can ensure expected priority transfer performance, cope with steep bandwidth fluctuations of the network, and realize priority control and retransmission control consistent with each other. And providing a communication control method.

  The present invention is a monitoring system using a network interconnection device (network device) for connecting a local network to which a plurality of communication terminals are connected and a wide area network to which a management center (receiving node, management device) is connected. To achieve the above object, as shown in FIG. 2, the network interconnection apparatus performs retransmission control outside the communication protocol when sending packets to the wide area network (24). In the function block 24, priority control and retransmission control are not performed independently, but the retransmission data is incorporated into one of the candidates in the same manner as the first data to be sent (hereinafter referred to as initial transmission data), and the priority is considered. Determine the sending order. In addition, the number of packets to be transmitted is determined according to the bandwidth fluctuation status of the wide area network. As a result, as shown in FIG. 9, when the wide area network condition deteriorates rapidly while transmitting a low-priority packet 915 (92), the retransmission of the low-priority packet is temporarily stopped, and the priority is A high packet is sent out (97).

According to the first solution of the present invention,
A receiving node that collects data from the communication terminal;
A network device for inputting the data from the communication terminal and transmitting the data to the receiving node;
The network device is:
In accordance with the presence or absence of a confirmation notification indicating that data has arrived at the receiving node, a retransmission processing unit for retransmitting data;
For each data type, the initial transmission data that has not been transmitted to the receiving node among the data from the communication terminal, and the retransmission data that has been transmitted to the receiving node and is used for retransmission are priorities within the data type. A data storage area for storing corresponding to,
A transmission order storage area in which the transmission order is stored in advance according to the combination of the data type and the priority order;
A control unit that refers to the combination of the data type and the priority order of the transmission order storage area in the order indicated by the transmission order, and reads and transmits the data of the corresponding priority order from the data storage area corresponding to the corresponding data type; A monitoring system is provided.

According to the second solution of the present invention,
A network device that inputs data from a communication terminal and transmits it to a receiving node that collects data from the communication terminal,
In accordance with the presence or absence of a confirmation notification indicating that data has arrived at the receiving node, a retransmission processing unit for retransmitting data;
For each data type, the initial transmission data that has not been transmitted to the receiving node among the data from the communication terminal, and the retransmission data that has been transmitted to the receiving node and is used for retransmission are priorities within the data type. A data storage area for storing corresponding to,
A transmission order storage area in which the transmission order is stored in advance according to the combination of the data type and the priority order;
A control unit that refers to the combination of the data type and the priority order of the transmission order storage area in the order indicated by the transmission order, and reads and transmits the data of the corresponding priority order from the data storage area corresponding to the corresponding data type; The network apparatus is provided.

According to the third solution of the present invention,
A receiving node that collects data from the communication terminal; and a network device that inputs the data from the communication terminal and transmits the data to the receiving node, the network device indicating that the data has reached the receiving node A communication control method in a system having a retransmission processing unit for retransmitting data according to the presence or absence of a confirmation notification,
For each data type, storing initial transmission data that has not been transmitted to the receiving node among data from the communication terminal, and retransmission data that has been transmitted to the receiving node and is used for retransmission in a data storage area; ,
For each data type, giving priority within the data type to the initial transmission data and retransmission data stored in the data storage area;
The transmission order storage area in which the transmission order is stored in advance according to the combination of the data type and the priority order is referred to in the order indicated by the transmission order, and the corresponding priority order is determined from the data storage area corresponding to the corresponding data type. A communication control method including the step of reading and transmitting the data.

  According to the present invention, there are provided a monitoring system, a network device, and a communication control method that can ensure expected priority transfer performance, cope with steep bandwidth fluctuations of the network, and realize priority control and retransmission control consistent with each other. can do.

1 is an overall configuration diagram of a communication system according to a first embodiment of the present invention. It is a figure which shows the system configuration example by this invention. It is a detailed block diagram of the priority / retransmission control function of the network interconnection device according to the first embodiment. It is a figure which shows an example of the sending order reference table based on Example 1. FIG. It is a figure which shows an example of the newest data holding table based on Example 1. FIG. It is a figure which shows an example of the past data holding table based on Example 1. FIG. It is a figure which shows another example of the sending order reference table based on Example 1. FIG. It is a figure explaining the communication flow at the time of performing priority control and retransmission control independently using the communication protocol with a retransmission function. It is a figure explaining the communication flow by this invention. It is a figure which shows the system configuration example at the time of performing priority control and retransmission control independently using the communication protocol with a retransmission function.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an overall configuration diagram of a communication system capable of realizing various types of monitoring according to the present embodiment.
In the drawing, reference numerals 10 and 14 denote a wide area network (first network) called WAN (Wide Area Network) and a local network (second network) called LAN (Local Area Network), respectively. Reference numeral 11 denotes a network interconnection device (network device) that interconnects them. A variety of sensors such as temperature sensors and a plurality of communication terminals 12 such as surveillance cameras are connected to the local network 14. A management center 13 is connected to the wide area network 10.
The wireless terminal 12 includes a sensor unit such as a sensor or a monitoring camera and a communication function unit. The wireless terminal 12 transmits the sensor data obtained by the sensor unit to the network interconnection device 11 by the communication function unit.

FIG. 2 shows a system configuration example of the present embodiment.
The system includes a network interconnection device 11 and a management center 13. The network interconnection apparatus 11 includes a local network communication function unit 25, a priority / retransmission control function unit 24, and a wide area network communication function unit 21. The management center 13 includes a wide area network communication function unit 26, a priority / retransmission control function unit 27, and a screen display function unit 28.

FIG. 3 shows details of the functions and table configuration of the priority / retransmission control function unit 24 of the network interconnection apparatus in the monitoring system of the present embodiment.
The latest data holding table (second data storage area) 32 for each data type, the past data holding table (data storage area) 33 for each data type, and the sending order reference table (sending order storage area) 37 are stored in an appropriate memory. Remembered. The other functions are executed by the priority / retransmission control function unit 24.

  In the figure, sensor data from the communication terminal 12 of FIG. 1 is input to the priority / retransmission control function unit 24 via the local network communication function unit 25 shown in FIG. In the received data identification / distribution block 31, the data type is identified by the packet header of the sensor data, and registered in the latest data holding table 32 and the past data holding table 33 of the corresponding type. In the arithmetic processing block 34, statistical processing of sensor data registered in the latest data holding table, threshold determination processing for alarm presence / absence, and the like are performed to generate another type of data (average value, alarm status) and the like. The generated data is registered in the corresponding latest data holding table 32 (different from the above) and the past data holding table 33. For example, it has a latest data holding table 32 and a past data holding table 33 for data types corresponding to the contents of statistical processing and the contents of threshold determination processing. Some data such as alarm status is also referred to when selecting which one of a plurality of transmission order reference tables 37 to use by the filter selection function 36. On the other hand, from the management center 13 in FIG. 1, wide area network communication status information and retransmission control information (Ack / Nack) are input to the priority / retransmission control function unit 24. Information on the communication status of the wide area network is determined by the network quality determination function (network quality determination function unit) 35. Based on the determination result, the filter selection function (selection function unit) 36 uses the filter function (control unit) 310. The number of lines to be read out from the transmission order reference table 37 selected in (1) is determined. Note that the packet transmission amount may be determined, the transmission order reference table 37 may be sequentially read accordingly, and reading may be stopped when the determined packet transmission amount is reached. The Ack reception function 37 updates the past data holding table 33 for each type for the sensor data for which Ack has been received (38), and the priority order determination function 39 determines the priority order among the past data of that type ( 39). The filter function 310 selects the data of the designated data type and the priority order from the latest data holding table 32 for each type and the past data holding table 33 for each type in accordance with the transmission order reference table 37 previously selected, and the wide area Send to network 10. Also, the registration information of the above-mentioned past data holding table 33 is updated for the transmitted data (311).

  A block that executes the Ack reception function 37 and the type-specific past data holding table Ack update 38 may be referred to as a retransmission processing unit (or a confirmation signal processing unit). For example, the retransmission processing unit performs processing for the network interconnection device 11 to retransmit data according to the presence or absence of Ack (confirmation notification) indicating that data has arrived at the management center 13.

  FIG. 5 shows a configuration example of the latest data holding table 32. The received time information 52 is recorded together with the sensor data value 51. There is always only one data registered in the latest data holding table, and the priority is always the first. Since the latest data is also stored in the past data holding table 33, for example, an address indicating a storage location, a pointer, and the like may be stored in the latest data holding table 32.

  FIG. 6 shows a configuration example of the past data holding table 33. Similar to the latest data holding table 32, the received time information 62 is recorded together with the sensor data value 61 in the past data holding table 33. Next, the transmission flag 63 is set to 1 for the data selected and transmitted even once by the filter function 310. At the time of the above-described table update 38, the Ack reception flag 64 is set to 1 for the data for which the Ack reception function 37 has received the Ack. At the time of the priority order determination 39 described above, regarding the data for which both the transmission flag 63 and the Ack reception flag 64 are 1, it is determined that the data has safely arrived at the center and no longer needs to be retransmitted, and is excluded from the prioritization target. (66). Which data should be output first among the data having the Ack reception flag of 0 is determined and given a priority (39).

  As an example of a criterion for determining the priority order, in FIG. 6, regardless of the transmission flag 0/1, among the data with the Ack reception flag 0, the older the time information, the higher the priority order is set. As another example of the standard, it is possible to delete data that has passed for a certain period of time after being registered in the table, or to remove it from the prioritization target. It is also possible to prioritize data with a transmission flag of 0 (never sent yet) over data with 1 (already sent once). Since the data is not subject to retransmission control within a certain period of time after it is received, it is excluded from the priority given. The criterion for determining the priority order may be different for each data type.

For example, in data type A (first data type), the priority of retransmission data is higher than the priority of initial transmission data, and in data type B (second data type), the priority of retransmission data is The order may be lower than the priority order of the initial transmission data. In this way, flexible priority setting according to the contents / characteristics can be performed according to the type of sensor data.
Further, when the communication state continues to be good and there is no data to be retransmitted (Ack is received for all transmission data), for example, all the priority items are displayed as “-” (not subject). Shall.

  FIG. 4 shows a configuration example of the transmission order reference table 37. In this table, the wide area network 10 includes a combination of a plurality of data types, selection information (transmission type) indicating latest data and past data (retransmission data and first transmission data sent in the past), and priorities. Specifies the order of sending to. The filter function 310 reads the table 37 in order from the top, selects the data of the specified priority order 42 in the past data holding table 33 or the latest data holding table 32 corresponding to the described data type 41 and selects the wide area network 10. To send. The filter selection function 36 changes the number of packets permitted to be transmitted to the wide area network 10 based on the value indicating the communication status of the wide area network 10 determined by the network quality determination function 35. When the communication condition is bad, the number of transmitted packets is reduced to suppress packet transmission delay. When the communication condition is good, increase the number of packets to be sent and increase the throughput. By such a method, a monitoring system is provided that can cope with steep bandwidth fluctuations in the network and can implement priority control and retransmission control consistent with each other.

In the example of FIG. 4, since the data type A (high priority) is set to be transmitted earlier than the data type (low priority), the high priority initial transmission data is transmitted before the low priority retransmission data. it can.
A method for referring to the transmission order reference table in FIG. 4 will be described below in association with the flowchart in FIG. “High-priority data” in FIG. 9 corresponds to “data type A” in FIG. 4, “low-priority data” in FIG. 9, and “data type B” in FIG. For easy understanding, when the “wide area network status” graph displayed at the right end of FIG. 9 belongs to “bad (congested)” on the left side, the filter selection function 36 permits only one number of transmitted packets. However, when it belongs to “good (empty)” on the right side, up to two outgoing packets are permitted. Further, it is assumed that there is no data to be retransmitted in both data types A and B at time t. In the flowchart of FIG. 9, the following operations are performed at each time.

  At time t, since the “wide area network state” is “good” (91), the filter selection function 36 permits the number of transmitted packets to two. Since there is no data to be retransmitted at time t, the sending order 1 and 2 are skipped without corresponding data in the sending order reference table of FIG. Next, the latest data of data type A in the transmission order 3 is transmitted (94). Next, the sending orders 4 and 5 are also skipped without corresponding data. Next, the latest data of the data type B in the transmission order 6 is transmitted (95). When the number of transmission packets reaches 2, the filter function 310 stops reading the transmission order reference table. Further, the filter function 310 updates “transmission” flag information corresponding to each data transmitted at time t in the past data holding table 33 to “1”.

  At time t + 1, since the “wide area network state” is “bad” (92), the filter selection function 36 permits only one number of transmitted packets. In FIG. 9, Ack is returned to the data of data type A at time t (96), so transmission order 1 and 2 in FIG. 4 are skipped without corresponding data. Next, the latest data of the data type A in the transmission order 3 is transmitted (97). When the number of transmission packets becomes 1, the filter function 310 stops reading the transmission order reference table. Further, the filter function 310 updates the “transmission” flag information corresponding to the data transmitted at time t + 1 in the past data holding table 33 to “1”. Here, since Nack is returned to the data of data type B at time t, there is retransmission data, but according to the transmission order of the transmission order reference table 37, the latest data of data type A is transmitted as described above. .

  At time t + 2, since the “wide area network state” is “bad” (92), the filter selection function 36 permits only one transmission packet number. In FIG. 9, since Nack is returned to the data (t + 1) of the data type A at time t + 1 (98), there is retransmission data in the past data holding table 33 of the data type A, and the data type A of the transmission order 1 in FIG. Retransmission data (t + 1) is sent (99). When the number of transmission packets becomes 1, the filter function 310 stops reading the transmission order reference table. Further, the filter function 310 updates the “transmission” flag information corresponding to the data transmitted at time t + 2 to “1” in the past data holding table 33.

  At time t + 3, since the “wide area network state” is “good” (93), the filter selection function 36 permits up to two outgoing packets. In FIG. 9, since Nack is returned to the retransmission data (t + 1) of the data type A at time t + 2 (910), the retransmission data (t + 1) of the data type A in the transmission order 1 of FIG. 4 is transmitted (911). Next, the past data (t + 2) of the data type A in the transmission order 2 is transmitted (912). For example, the data that was supposed to be sent at time t + 2 can be sent for the first time at time t + 3 because only retransmission data (t + 1) can be sent at time t + 2. When the number of transmission packets reaches 2, the filter function 310 stops reading the transmission order reference table 37. Further, the filter function 310 updates the “transmission” flag information corresponding to each data transmitted at time t + 3 to “1” in the past data holding table 33.

FIG. 7 shows another configuration example of the transmission order reference table 37 in the present invention. It is possible to define independently for each data type whether the latest data, the first transmission data, or the past data including the retransmission data is transmitted with priority. In this configuration example, for example,
Data type priority: Data type A> Data type B> Data type C
Latest and past priorities: Past> latest for data type A (third data type), latest> past for data types B and C (fourth data type). For example, for information that is difficult to be lost during transmission, such as an alarm status, the past data is prioritized over the latest data and the priority between the data types is set higher as in data type A in FIG. For example, for information that becomes less meaningful when it becomes older to some extent, such as image data of a monitoring camera, the latest data is given priority over past data as data types B and C in FIG. By combining these conditions and defining them in a single table, priority control and retransmission control consistent with each other can be realized.

2. Configuration example 1
This monitoring system is, for example,
A management device for collecting data from a communication terminal;
A network device that inputs the data from the communication terminal and transmits the data to the management device, and the network device has a function of retransmitting the data according to the presence or absence of a confirmation notification indicating that the data has arrived at the management device. And
The network device is:
A data storage area having a first storage area for storing data of the first transmission type and a second storage area for storing data of the second transmission type for each data type indicating the type of input data ,
Corresponding to the combination of the data type and the transmission type, a transmission order storage area in which the transmission order is stored in advance,
Control that reads the data from the first storage area or the second storage area according to the corresponding data type and transmission type by referring to the combination of the data type and the transmission type in the transmission order storage area in the order indicated by the transmission order. And
The first transmission type indicates initial transmission data that has not been transmitted to the management device among data from the communication terminal, and the second transmission type is a retransmission that has been transmitted to the management device and is used for retransmission. Show data or
The first transmission type may indicate the latest data of data from the communication terminal, and the second transmission type may be a monitoring system indicating past data of data from the communication terminal.
In addition to the monitoring system, a network device in the monitoring system and a communication control method in the monitoring system can be configured.

3. Configuration example 2
The monitoring system is, for example, a monitoring system using a network interconnection device that interconnects a local network to which a plurality of communication terminals are connected and a wide area network to which a management center is connected.
The monitoring system has a mechanism for transmitting a plurality of types of monitoring data having different priorities and notifying the network interconnection device that the data has arrived at the management center,
The network interconnection device is:
Use the first table for each data type to manage whether or not to continue resending data,
Determining the priority in the data managed in the first table for each data type;
Use the second table to manage the packet transmission order to the wide area network,
Selecting data of the specified priority order from the data managed by the first table corresponding to the data type specified by the second table and sending it to the wide area network;
In the second table, a plurality of data types, various types of initial transmission data and retransmission data, and a combination of a plurality of retransmission data are collectively defined,
The amount of transmitted data is adjusted according to the communication status of the wide area network.

  INDUSTRIAL APPLICABILITY The present invention is useful as a monitoring technology that performs priority control and retransmission control in consideration of communication bandwidth variation using a monitoring system that uses, for example, a sensor or a monitoring camera, particularly a wide area network such as a mobile phone that has severe communication bandwidth variation. .

DESCRIPTION OF SYMBOLS 10 ... Wide area network 11 ... Network interconnection apparatus 12 ... Communication terminal 13 ... Management center 14 ... Local network 21 ... Wide area network communication function (with retransmission function)
22 ... Priority control function 23 ... Retransmission control information (Ack / Nack)
24 ... Priority / Retransmission control function 25 ... Local network communication function 31 ... Received data identification / distribution function 32 ... Latest data holding table registration function for each type 33 ... Past data holding table registration function for each type 34 ... Arithmetic processing function 35 ... Network quality Determination function 36 ... Filter selection function 37 ... Ack reception function 38 ... Past data holding table Ack update function for each type 39 ... Past data holding table priority order determination function for each type 310 ... Filter function 311 ... Transmission flag update function 51, 61 ... Sensor Data 52, 62 ... Time information 63 ... Transmission flag 64 ... Ack reception flags 42, 65, 66, 72 ... Priority order 41, 71 ... Data types 81, 95 ... Low priority data 82, 92 ... Period in which the wide area network state is bad 83 ... Low priority data retransmission periods 91 and 93 ... Wide area network Click state is good period 94 ... priority high data 96 ... Ack
97: Canceling retransmission of low-priority data and high-priority data transmission timing 98, 910 ... Nack
99, 911, 912 ... High priority data retransmission period

Claims (13)

A receiving node that collects data from the communication terminal;
A network device for inputting the data from the communication terminal and transmitting the data to the receiving node;
The network device is:
In accordance with the presence or absence of a confirmation notification indicating that data has arrived at the receiving node, a retransmission processing unit for retransmitting data;
For each data type, the initial transmission data that has not been transmitted to the receiving node among the data from the communication terminal, and the retransmission data that has been transmitted to the receiving node and is used for retransmission are priorities within the data type. A data storage area for storing corresponding to,
A transmission order storage area in which the transmission order is stored in advance according to the combination of the data type and the priority order;
A control unit that refers to the combination of the data type and the priority order of the transmission order storage area in the order indicated by the transmission order, and reads and transmits the data of the corresponding priority order from the data storage area corresponding to the corresponding data type; Having a monitoring system.   The network device receives data detected by the sensor or data captured by the camera from the communication terminal including the sensor or camera, and transmits the data or statistical data thereof to the receiving node. The monitoring system according to 1.   The monitoring system according to claim 1, wherein at least a part of a network between the network device that retransmits data and the receiving node is a wireless communication network. The network device is:
A network quality determination function unit for monitoring a communication state of the network between the network device and the receiving node and obtaining an index representing the communication state;
A selection function unit that determines a data transmission amount within a predetermined time according to the index,
The control unit transmits data by referring to the transmission order storage area according to a transmission order until the amount of data transmitted within a predetermined time reaches a data transmission amount determined by the selection function unit. The monitoring system described.   2. The monitoring system according to claim 1, wherein whether the first transmission data or the retransmission data is preferentially transmitted can be defined independently for each data type according to the priority. In the first data type, the priority of retransmission data is higher than the priority of initial transmission data,
6. The monitoring system according to claim 5, wherein, in the second data type, the priority order of retransmission data is lower than the priority order of initial transmission data. The data type corresponds to the data transfer priority,
In the transmission order storage area, the transmission order corresponding to the combination of the high priority data type and the priority order corresponding to the initial transmission data is the combination of the low priority data type and the priority order corresponding to the retransmission data. The monitoring system according to claim 1, wherein the order is higher than the corresponding transmission order. A second data storage area for storing information for specifying the latest data among the data from the communication terminal;
The transmission order storage area has a transmission order according to a combination of the data type, selection information indicating whether the latest data is transmitted or past data including initial transmission data and retransmission data is transmitted, and the priority order. Remembered,
According to the selection information of the transmission order storage area, it is possible to independently define for each data type which of the latest data and the past data including initial transmission data and past data including retransmission data is to be preferentially transmitted. The monitoring system according to claim 1. In the transmission order storage area,
In the third data type, the transmission order corresponding to the selection information indicating past data is earlier than the transmission order corresponding to the identification information of the latest data,
The monitoring system according to claim 8, wherein, in the fourth data type, the transmission order corresponding to the selection information indicating past data is lower than the transmission order corresponding to the identification information of the latest data.   The monitoring system according to claim 1, wherein data received from the communication terminal is sequentially stored in the data storage area, but is not included in a target to be prioritized within a predetermined first time after reception.   2. The data of the first transmission data and the retransmission data stored in the data storage area are deleted after a predetermined second time has elapsed after storage, or the data is not included in a priority order. Monitoring system. A network device that inputs data from a communication terminal and transmits it to a receiving node that collects data from the communication terminal,
In accordance with the presence or absence of a confirmation notification indicating that data has arrived at the receiving node, a retransmission processing unit for retransmitting data;
For each data type, the initial transmission data that has not been transmitted to the receiving node among the data from the communication terminal, and the retransmission data that has been transmitted to the receiving node and is used for retransmission are priorities within the data type. A data storage area for storing corresponding to,
A transmission order storage area in which the transmission order is stored in advance according to the combination of the data type and the priority order;
A control unit that refers to the combination of the data type and the priority order of the transmission order storage area in the order indicated by the transmission order, and reads and transmits the data of the corresponding priority order from the data storage area corresponding to the corresponding data type; The network device provided. A receiving node that collects data from the communication terminal; and a network device that inputs the data from the communication terminal and transmits the data to the receiving node, the network device indicating that the data has reached the receiving node A communication control method in a system having a retransmission processing unit for retransmitting data according to the presence or absence of a confirmation notification,
For each data type, storing initial transmission data that has not been transmitted to the receiving node among data from the communication terminal, and retransmission data that has been transmitted to the receiving node and is used for retransmission in a data storage area; ,
For each data type, giving priority within the data type to the initial transmission data and retransmission data stored in the data storage area;
The transmission order storage area in which the transmission order is stored in advance according to the combination of the data type and the priority order is referred to in the order indicated by the transmission order, and the corresponding priority order is determined from the data storage area corresponding to the corresponding data type. A communication control method including reading and transmitting the data.

Images