JP2004201127A - Communication controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication controller capable of dynamically and compactly controlling the data transfer amount per unit time. <P>SOLUTION: An image storage server 12 which returns an enabling signal for permitting transmission of the next packet signal to a camera device 16 in accordance with a packet signal transmitted from the camera device 16 refers to a target communication speed of a camera device 16 set by an operator, detects a real communication speed of a packet signal transmitted from the camera device 16 and adjusts return timing of an enabling signal on the basis of the target communication speed and the real communication speed of the camera device 16 to return the enabling signal. As a result, by only control with the image storage server 12, the communication speed of a signal from the camera device 16 to a desired communication speed can be easily limited. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a communication control device, and more particularly to, for example, a communication control device that returns a response signal to a communication terminal when a signal received from the communication terminal satisfies a condition.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, when a data server sends data to a terminal device via a communication line, a communication band usable for the terminal device is registered and transmitted autonomously in order to control a data transfer amount (communication band) per unit time. The amount of data to be adjusted. In addition, a communication band usable for each terminal device is registered and adjusted in a packet switching device such as a router interposed on a communication line connecting the data server and the terminal device.
[0003]
[Problems to be solved by the invention]
However, for example, in a system in which one server is connected to a plurality of terminal devices, when the communication band (available communication band) usable by each terminal device dynamically changes, the use of each terminal device It is necessary to dynamically set possible communication bands individually. That is, each communication terminal or packet switching device sets the usable communication band according to the change in the actual usable communication band. In this case, since each communication terminal or packet switching apparatus is independently set, it is impossible to cope with a change in communication band that affects the entire system.
[0004]
As another control method, there is a method in which a server uniformly manages a usable communication band for each terminal device in order to cope with a change in the communication band that affects the entire system. In this method, the available communication band for each terminal device managed by the server is notified to the terminal device as necessary, and the terminal device sets the notified usable communication band to the device. However, in this method, there is a time lag between the change of the actually usable communication band and the change of the setting of the usable communication band of the terminal device, or the available communication band value between the server and the terminal device. There is a drawback that a communication device for performing the above communication is required and the network control unit becomes complicated.
[0005]
Therefore, a main object of the present invention is to provide a communication control device capable of dynamically and simply controlling a data transfer amount per unit time.
[0006]
[Means for Solving the Problems]
According to the present invention, when a signal satisfying the condition is received from the communication terminal, the communication control device that returns the permission signal for permitting transmission of the next signal to the communication terminal includes the first detection unit that detects the target communication speed of the communication terminal. Means, a second detection means for detecting an actual communication speed of the communication terminal, and a return means for returning a permission signal at a timing based on the target communication speed and the actual communication speed.
[0007]
[Action]
When a signal satisfying the condition is received from the communication terminal, the communication control device returns a permission signal for permitting transmission of the next signal to the communication terminal, wherein the first detection means detects a target communication speed of the communication terminal. The second detecting means detects an actual communication speed of the communication terminal. The return means returns the permission signal at a timing based on the target communication speed and the actual communication speed.
[0008]
In a preferred aspect, the detecting means detects the actual communication speed based on the difference between the previous reception timing and the current reception timing.
[0009]
In another preferred aspect, the first signal returning means for returning the permission signal promptly when the actual communication speed of the returning means is equal to or lower than the target communication speed is included.
[0010]
In another preferred aspect, the apparatus further comprises a calculating unit for calculating a delay time associated with a difference between the actual communication speed and the target communication speed, and the returning unit includes a delay period when the actual communication speed is higher than the target communication speed. And second signal returning means for returning a permission signal after the elapse of the time.
[0011]
【The invention's effect】
According to the present invention, the data transfer from the communication terminal can be appropriately delayed by transmitting the response signal to the reception signal from the communication terminal at a timing based on the result of the determination by the determination unit. The communication speed of the transmitted signal can be easily limited to a desired communication speed.
[0012]
The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.
[0013]
【Example】
Referring to FIG. 1, a remote monitoring system 10 of this embodiment includes an image storage server 12 having a storage capacity capable of storing a large number of images. The image storage server 12 is connected to a plurality of camera devices 16, 16,.
[0014]
FIG. 2 shows the internal configuration of the image storage server 12. The internal memory 102 stores a program 110 executed by the CPU 106 and a communication band limitation table 112 in addition to the image data sent from the camera device 16. The HDD 104 stores a communication band limit setting table 114 to which a value is input by an operator. The HDD 104 stores a large amount of image data sent from the camera device 16. By executing the program, the CPU 106 supports a protocol corresponding to the camera device 16 and receives image data transmitted from the camera device 16. Communication with the outside is performed via the network I / F 108.
[0015]
Each camera device 16 is configured as shown in FIG. The subject is photographed by the image sensor 202, and the photographed image data is temporarily stored in the internal memory 210. The flash memory 204 records a program 212 executed by the CPU 208. The CPU 208 transmits the image data shot by executing the program 212 recorded in the flash memory 204 to the image storage server 12. Communication with the outside is performed via the network I / F 206.
[0016]
FIG. 5 shows an example of the items of the communication band limitation table 112 and the values of the respective items. The communication band limitation table 112 has items of all the camera devices 16 connected to the image storage server 12 via the network. Items possessed by each camera device 16 are “maximum allowable data amount per second” and “fixed flag”. The value of the “maximum allowable data amount per second” can be obtained by referring to the communication band limitation setting table 114 or calculated from the connection status of the camera device. More specifically, the value of the “maximum allowable data amount per second” is determined. For the camera device 16, there is a set value set by the operator in the communication band limit setting table 114. In this case, the set value is set to the value of the “maximum allowable data amount per second” of the camera device 16 in the communication band limitation table 112. On the other hand, if there is no set value set by the operator in the communication band limit setting table 114 for the camera device 16, the “maximum reception allowable data per second” is set so as to average the camera devices having no set value by the operator. The value of "quantity" is calculated. The “fixed flag” is “1” (true) when the value of “maximum allowable data amount per second” is referenced from the communication band limitation setting table 114, and is “0” (false) otherwise. . Therefore, by referring to the “fixed flag”, it can be determined whether or not the value of the “maximum allowable data amount per second” is specified by the operator.
[0017]
FIG. 6 shows an example of the items of the communication band limitation setting table 114 and the values of the respective items. The communication band limit setting table 114 has an item of the camera device 16 for which a setting instruction has been given by the operator and an item of “total communication capacity” that can be communicated through the communication line. For each item, a “maximum allowable data amount per second” can be set, and this value is input by the operator. Note that the communication speed of a camera device in which the setting value of the “maximum reception capacity data amount per second” is set to “0” is not limited.
[0018]
The CPU 106 of the image storage server 12 executes the processing shown in FIG. 7 according to the program 110 stored in the internal memory 102. First, an application processed by the image storage server 12 is executed in step S101. Next, in step S103, it is determined whether or not there is a data reception request from the camera device 16. If YES, step S113 and subsequent steps are executed. If NO, step S105 and subsequent steps are executed.
[0019]
In step S113, the communication band limitation table 112 is referred to, and in the next step S115, it is determined whether or not the item of the camera device 16 which has issued the data reception request is in the communication band limitation table 112. If there is an item, the process proceeds to step S125 to activate the data reception processing handler. If there is no item, the process proceeds to step S117, and the communication band limitation setting table 114 is referred to. In the next step S119, the item of the camera device 16 which has issued the reception request is added to the communication band limitation table 112. If there is a setting value referred to in step S117, the content of the added item is set in the “maximum allowable amount of received data per second” and the fixed flag is set to “1”. If there is no setting value referred to in step S117, the fixed flag is set to "0" while "maximum permissible received data per second" is left blank.
[0020]
Next, the process proceeds to step S121, in which the value of the “maximum allowable amount of received data per second” of the camera device 16 whose fixed flag is “0” is calculated so as to be averaged. The calculation of the value is performed by a function of the total communication capacity, the set value of the camera device whose fixed flag is “1”, and the number of camera devices whose fixed flag is “0”. In the next step S123, the communication band limitation table 112 is updated based on the result calculated in step S121.
[0021]
When the update of the communication band limitation table 112 is completed, the process proceeds to step S125, and the “data reception processing handler” is activated. The “data reception processing handler” will be described later in detail. When the activation of the “data reception processing handler” is completed, the process returns to step S101 and normal application processing is performed.
[0022]
When there is no reception request from the camera device 16 in step S103, first, in step S105, it is checked whether the camera device 16 in the communication band limitation table 112 is connected to the network. In the next step S107, if there is a camera device 16 that has been disconnected, the camera device 16 that has been disconnected in step S109 is deleted from the communication band limitation table 112, and in the next step S111, the communication band limitation table 112 is deleted. Update the value. The value is updated in the same manner as in step 123 described above.
[0023]
When the update of the communication band limitation table 112 is completed, the process proceeds to step S127, and it is determined whether a power-off command has been input to the image storage server 12. If a power-off command is input to the image storage server 12, the image storage server 12 turns off the power after the end processing. If the power-off command has not been input to the image storage server 12, the process returns to step S101 and the application processing of the image storage server 12 is performed.
[0024]
The data reception processing handler in step S125 in FIG. 7 is executed according to the flow shown in FIGS. First, in step S131, the “maximum received data per second” corresponding to the camera device 16 that has requested data reception is acquired by referring to the communication band limitation table 112, and is substituted for the variable “MAX”. When the assignment to “MAX” is completed, the process moves to step S133, and it is determined whether or not there is a communication band limitation for the camera device that has requested data reception. Whether or not there is a communication band limitation is determined from the value of “MAX” obtained by referring to step S131. When the value of “MAX” is positive, there is a communication band limitation, and when the value of “MAX” is “0” or a negative value, there is no communication band limitation. If it is determined in step S133 that there is a communication band limitation, steps S135 to S143 are executed. If it is determined in step S133 that there is no communication band limitation, the process proceeds to step S145.
[0025]
Steps S135 to S143 are pre-processing when there is a communication band limitation. In step S135, a measurement unit time (S) is calculated. The measurement unit time is a function using “MAX” as a parameter. Next, in step S137, the basic packet interval time (T) is calculated. The basic packet interval time is a function using “MAX” as a parameter. Next, in step S139, "0" is substituted for the received data amount (D) within a unit time. When the substitution is completed, the packet interval measurement timer (p) and the measurement unit time timer (s) are reset in steps S141 and S143, and each timer is started from "0". When the reset of the timer is completed, the process proceeds to step S145.
[0026]
In step S145, a packet from the camera device is received. At this time, the size of the packet is “d”. Upon completion of the packet reception, it is determined in step S147 whether there is a communication band limitation. If there is a communication band limitation, the process proceeds to step S149, and if there is no communication band limitation, the process proceeds to step S171. The determination as to whether or not there is a communication band limitation is made based on the value of “MAX” as in step S133.
[0027]
In step S149, the received data amount (D) per unit time is updated by adding the size of the packet received in step S145. When the update of “D” is completed, the process proceeds to step S151, and it is determined whether or not the measurement unit time timer (s) has exceeded the measurement unit time (S). If the measurement unit time timer (s) exceeds the measurement unit time (S), the packet interval measurement timer (p), the received data amount within the unit time (D), and the unit time measurement timer are determined in steps S153 to S157. (S) is reset, and the process proceeds to step S171 to immediately return "ACK" (acknowledge) or "NAK" (negative acknowledge). On the other hand, if the measurement unit time timer (s) has not exceeded the measurement unit time (S) in step S151, the process moves to step S159.
[0028]
In step S159, it is determined whether or not the packet interval measurement timer (p) has exceeded the basic packet interval time. If the packet interval measurement timer (p) has exceeded the basic packet interval time, the packet interval measurement timer is reset in step S161, and the process proceeds to step S171 to immediately return "ACK" or "NAK". If the packet interval measurement timer (p) has not exceeded the basic packet interval time, the process from step S163 is performed. In step S163, the delay time (t) is calculated. The delay time (t) includes the amount of received data within a unit time (D), the packet size (d), the packet interval measurement timer value (p), the measurement unit time (S), the measurement unit time timer value (s), and This is a function using the basic packet interval time (T) as a parameter. When the calculation of the delay time (t) is completed, the packet interval measurement timer is reset in step S165, and the process waits for the delay time (t) in step S167. When the waiting for the delay time (t) is completed, it is determined in step S169 whether the measurement unit time timer (s) has exceeded the measurement unit time (S). If the measurement unit time timer (s) exceeds the measurement unit time (S), after resetting the received data amount (D) within the unit time and the unit time measurement timer (s) in steps S155 to S157, Proceed to step S171. On the other hand, if the measurement unit time timer (s) has not exceeded the measurement unit time (S) in step S169, the process directly proceeds to step S171.
[0029]
In step S171, it is determined whether the data of the packet received from the camera device is correct. The determination as to whether the data of the packet is correct is made based on the validity of the packet included in the packet, a sequence number that guarantees the order, and a block check code such as a checksum and a CRC. If the result of this determination is that the packet data is correct, "ACK" is sent out in step S173. Then, if it is determined in step S175 that the reception data has been completed by the end determination of the reception data, the process returns to the main processing. On the other hand, if it is determined that the reception data has not been completed, the process moves to step S145 to receive the next packet.
[0030]
On the other hand, if it is determined in step S171 that the received packet is not correct, the process proceeds to step S177. If a retry is to be performed, “NAK” is transmitted and the process proceeds to step S145. If there is no retry, error processing is performed in step S181. After that, the process returns to the main process. In step S177, whether or not to retry is determined based on whether or not the number of retries of the same packet has reached a specified number.
[0031]
FIG. 4 is an illustrative view showing timings of a measurement unit time (S), a basic packet interval time (T), a packet interval time (p), and a delay time (t) when the data reception processing handler is executed by the CPU 106. Shown in
[0032]
FIG. 4A is an illustrative view showing a case where packets are received at the same interval as the basic packet interval time (T). In this case, since the maximum permissible data amount per second (communication band limit) matches the actual data communication speed, there is no delay time (t) for returning "ACK".
[0033]
FIG. 4B is an illustrative view when the packet reception interval is shorter than the basic packet interval time (T), that is, when the packet arrives at a communication speed higher than the communication band limit. Since the packet B arrives at a time shorter than the basic packet interval time (T) (the timing of FIG. 4A), an appropriate delay time (t) is set so that the packet C arrives at the timing of FIG. "ACK" is returned after. Since the packet C arrives at a timing earlier than that of FIG. 4A, a longer delay time than that of the packet B is given, and “ACK” is sent so that the packet D arrives at the timing of FIG. Is returning.
[0034]
FIG. 4C is an illustrative view showing a case where reception of the packet B is delayed. The packet B is received much later than the timing shown in FIG. 4A, that is, after the packet A has been received and a time much longer than the basic packet interval time has elapsed. Since the interval time between packet A and packet B is longer than the basic packet interval time, "ACK" for the reception of packet B is immediately returned. Since the packet C is received at a timing shorter than the basic packet interval time from the packet B, “ACK” is transmitted after an appropriate delay time (t) so that the next packet D arrives at the timing of FIG. Is returning. As for the next received packet D, the amount of received data within the unit time of measurement until the packet D is received is small and arrives at a timing later than the timing of the packet D in FIG. "ACK" is returned without a delay time even though the packet interval time is shorter than the basic packet interval time (T).
[0035]
The CPU 208 of the camera device 16 performs the processing shown in FIG. 10 according to the program 212 stored in the flash memory. First, in step S201, an application processed by the camera device is executed. Next, when there is a data transmission request from the application operating in step S203, the process proceeds to step S207, and the data transmission processing handler is activated. The data transmission processing handler will be described later in detail. If there is no data transmission request from the running application in step S203, the process proceeds to step S205. If there is no power-off command of the camera device in step S205, the process returns to step S201. When the power-off command is issued in step S205, the processing of the program 214 ends, and the power of the camera device is turned off.
[0036]
The data transmission processing handler of step S207 in FIG. 10 is executed according to the flow shown in FIG. First, the data to be transmitted is divided into packets in step S211. Next, in step S213, it is determined whether there is a packet to be transmitted. If there is a packet to be transmitted, steps S215 and subsequent steps are executed. If there is no packet to be transmitted, the data transmission processing handler ends.
[0037]
In step S215, the packet is transmitted to the image storage server 12. Then, in step S217, the process waits for a response of "ACK" or "NAK" from the image storage server 12. In the next step S219, it is determined whether or not the packet has been correctly transmitted. In the determination method, if the response obtained in step S217 is “ACK”, it means that the packet has been transmitted correctly, and the process returns to step S213 to transmit the next packet to be transmitted. If the reply obtained in step S217 is "NAK" or there is no reply and time-out has occurred, it means that the packet could not be transmitted correctly, and the process proceeds to step S221. In step S221, it is determined whether or not the packet whose transmission has failed is retransmitted. When retransmitting the packet, the process returns to step S215 to transmit the failed packet again. If the transmission is not performed again, the flow proceeds to step S223, performs error processing, and then returns to the main processing.
[0038]
The packet transmission of the camera device 16 is processed in the same procedure as the generally performed packet transmission. Therefore, the present invention is realized by changing the procedure of only the receiving side, and the transmitting side may be a general data transmitting device.
[0039]
As can be understood from the above description, by appropriately delaying the "ACK" or "NAK" timing returned from the receiving side, it is possible to limit the communication speed of each data transmission terminal.
[0040]
Although the “total communication capacity” in the communication band limit setting table 114 is input by the operator, a value obtained by measuring the actual communication capacity of the communication line and calculating the result may be used.
[Brief description of the drawings]
FIG. 1 is an illustrative view showing one embodiment of the present invention;
FIG. 2 is a block diagram showing a part of the embodiment in FIG. 1;
FIG. 3 is a block diagram showing another part of the embodiment of FIG. 1;
FIG. 4 is an illustrative view showing one portion of an operation of the embodiment in FIG. 1;
FIG. 5 is an illustrative view showing a part of the embodiment in FIG. 1;
FIG. 6 is an illustrative view showing another portion of the embodiment of FIG. 1;
FIG. 7 is a flowchart showing a part of the operation of the embodiment in FIG. 1;
FIG. 8 is a flowchart showing another portion of the operation of the embodiment in FIG. 1;
FIG. 9 is a flowchart showing another portion of the operation of the embodiment in FIG. 1;
FIG. 10 is a flowchart showing another portion of the operation of the embodiment in FIG. 1;
FIG. 11 is a flowchart showing another portion of the operation of the embodiment in FIG. 1;
[Explanation of symbols]
10 Communication System 12 Image Storage Server 16 Camera Device 20 Network

Claims (4)

When receiving a signal that satisfies the condition from the communication terminal, a communication control device that returns a permission signal that permits transmission of the next signal to the communication terminal,
First detecting means for detecting a target communication speed of the communication terminal;
A communication control device comprising: a second detection unit that detects an actual communication speed of the communication terminal; and a return unit that returns the permission signal at a timing based on the target communication speed and the actual communication speed. The communication control device according to claim 1, wherein the detection unit detects the actual communication speed based on a difference between a previous reception timing and a current reception timing. The communication control device according to claim 1, wherein the return unit includes a first signal return unit that returns the permission signal promptly when the actual communication speed is equal to or lower than the target communication speed. Further comprising a calculating means for calculating a delay time related to the difference between the actual communication speed and the target communication speed,
4. The method according to claim 1, wherein the return unit includes a second signal return unit that returns the permission signal after the elapse of the delay period when the actual communication speed is higher than the target communication speed. Communication control device.

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