JP2011097140A - Communication system and communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication system capable of improving the certainty of data transmission using an SV (supervision and control) line, when data communication is deteriorated by fading. <P>SOLUTION: Among wireless access devices, a wireless access device which has received data transmitted from a monitoring device through a wired network, transmits the received data to other wireless access devices by radio communication, and determines the presence or absence of deterioration in a data transmission/reception situation with the other wireless access devices. When it is determined that there is deterioration in the data transmission/reception situation, a request for extending a time-out period in the data transmission is transmitted to the monitoring device. Then, the monitoring device extends the time-out period in the data transmission based on the reception of the request for extending the time-out period. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a communication system and a communication method for transmitting and receiving data between devices.

  The communication system shown in FIG. 1 includes a monitoring device 10 and radio access devices 20a to 20d. Here, in the communication system shown in FIG. 1, each of the wireless access devices 20a to 20d (generically referred to as the wireless access device 20) is connected to the monitoring device 10 or another wireless access device via a wired network. Each having a communication means and a second communication means for connecting to another wireless access device via a wireless network, and has a serial connection configuration (the last wireless access device connected in series is Only the first communication means is connected to other wireless access devices via a wireless network).

  When the monitoring device 10 transmits data to, for example, the wireless access device 20b, wireless communication with the wireless access device 20b may deteriorate due to fading of wireless communication between the wireless access device 20a and the wireless access device 20b. There is. In the communication system as shown in FIG. 1, when data is transmitted and received, important data is transmitted by a main signal, and a supervisory control line (hereinafter referred to as an SV line) is used by using an additional bit to the main signal. For example, the monitoring device 10 may transmit, for example, data for updating the firmware of the wireless access device 20b using the SV line.

  However, in such a communication system, when communication degradation occurs due to fading in the wireless communication between the wireless access devices 20, control is performed to reduce the line capacity of the SV line as much as possible in order to secure the line capacity to transmit with the main signal. Is done. Specifically, this control is a control called an adaptive modulation function (AMR) that prevents line disconnection by changing the modulation of a signal to a lower-rate modulation. As a related technique, Patent Document 1 discloses a technique for transferring firmware data and updating firmware of an apparatus included in an information device.

JP 2006-260182 A

  Generally, a communication device has a time-out function for interrupting processing when data transmission is not completed within a specified time or when there is no response from a transmission partner. This is because the communication device performs infinite data retransmission and does not waste resources such as the CPU resource of the line or communication device.

  Here, if the transmission of data using the SV line is not completed within a specified time by reducing the line capacity of the SV line by the function of the AMR, the data communication between the monitoring device 10 and the wireless access device 20b is performed. A time-out occurs, and data transmission between the monitoring device 10 and the wireless access device 20b is interrupted. However, in order to complete the data transmission, the monitoring device 10 needs to transmit the interrupted data from the beginning. Therefore, the data is transmitted a plurality of times, and the amount of traffic flowing through the SV line increases accordingly. There is a problem.

  Accordingly, an object of the present invention is to provide a communication system and a communication method capable of improving the reliability of data transmission when data communication is deteriorated due to fading.

  To achieve the above object, the present invention provides a communication system comprising a data transmission device and a wireless relay device, wherein the wireless relay device is transmitted from the data transmission device and received via a wired network. A wireless communication unit that transmits the received data to a wireless access device by wireless communication, a first transmission / reception state deterioration determination unit that determines whether or not a data transmission / reception state of the wireless access device has deteriorated, and the first transmission / reception state deterioration determination unit A first time-out extension requesting unit that transmits a time-out extension request for data transmission to the data transmission device when it is determined that the data transmission / reception status is deteriorated in the data transmission device, Based on the reception of the request for extending the timeout period, a time schedule for extending the timeout period in the data transmission And setup time changing unit, a communication system comprising: a.

  In the communication system described above, the present invention provides a second transmission / reception condition deterioration determination unit that determines whether the wireless access device has deteriorated a data transmission / reception condition with the wireless relay device, and a second transmission / reception condition deterioration determination unit. A second time-out extension requesting unit that transmits a time-out time extension request in the data transmission to the data transmitting device via the wireless relay device when it is determined that the data transmission / reception status is deteriorated in FIG. It is characterized by.

  According to the present invention, in the communication system described above, when the first transmission / reception condition degradation determination unit determines whether or not fading has occurred, and determines that the fading has occurred, the data transmission condition has deteriorated. It is characterized by determining.

  According to the present invention, in the above-described communication system, the second transmission / reception state deterioration determining unit determines whether or not fading has occurred, and if the fading has occurred, the data transmission state is deteriorated. It is characterized by determining.

  In the communication system described above, the time-out time changing unit of the data transmission device may receive the data transmission / reception status improvement notification from either the wireless relay device or the wireless access device. The extended time-out period is changed to a predetermined initial value.

  The present invention is also a communication method in a communication system including a data transmission device and a wireless relay device, wherein a wireless communication unit of the wireless relay device is transmitted from the data transmission device and received via a wired network. The first transmission / reception status deterioration determining unit of the wireless relay device determines whether or not the data transmission / reception status of the wireless access device is deteriorated, and the wireless relay device A time-out extension request unit, when the first transmission / reception status degradation determination unit determines that the data transmission / reception status is degraded, transmits a timeout time extension request in the data transmission to the data transmission device; The time-out time changing unit of the data transmitting device receives the data transmission request based on the reception of the time-out time extension request. Is a communication method characterized by extending the time-out period in.

  According to the present invention, in the communication method described above, the second transmission / reception status degradation determination unit of the radio access device determines whether or not the data transmission / reception status of the radio relay device has deteriorated, and the second timeout of the radio access device When the extension request unit determines that the second transmission / reception status degradation determination unit has the degradation of the data transmission / reception status, the extension request unit issues a request for extending the timeout time in the data transmission to the data transmission device via the wireless relay device. It is characterized by transmitting.

  According to the present invention, a wireless access device 20 (wireless relay device) connected to the monitoring device 10 by wire or a wireless access device 20 that receives data from another wireless access device 20 by wireless communication is connected to a wireless communication partner. When fading of wireless communication is detected, the monitoring device 10 that is the data transmission source is requested to extend the timeout time. Thereby, even if the line capacity of the SV line in the wireless communication based on the operation of the AMR function is reduced, it is possible to improve the accuracy of maintaining the data communication through the SV line.

It is a block diagram which shows the structure of a communication system. It is a functional block diagram of a radio access device. It is a functional block diagram of a monitoring apparatus. It is a sequence diagram which shows the processing flow of a communication system. It is a 2nd block diagram which shows the structure of a communication system.

Hereinafter, a communication system according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a communication system according to the embodiment.
In this figure, reference numeral 10 is a monitoring device (data transmission device), and 20a to 20d are wireless access devices. The monitoring device 10 monitors each of the wireless access devices 20a to 20d (hereinafter collectively referred to as the wireless access device 20), transmits main data using the main signal, and adds bits to the main signal. Is used to configure a supervisory control line (SV line) and, for example, firmware data for updating the firmware of the wireless access device 20 is transmitted over a wired network.
Note that the monitoring device 10 uses SNMP or the like as a protocol for monitoring the wireless access device 20 and transmits data such as firmware data using an SV line using a protocol such as FTP or TFTP.

  The wireless access device 20 includes a wired communication unit connected to the monitoring device 10 or another wireless access device via a wired network, and a wireless communication unit connected to another wireless access device 20 via the wireless network. And having a configuration of a communication system having a serial connection form. Of the wireless access devices 20 connected in series, the wireless access device 20a connected closest to the monitoring device 10 is connected to the monitoring device 10 via a wired network, and is a communication system connected in series. The wireless access device 20d connected to the end is only connected to the wireless access device 20c via a wireless network. Among the wireless access devices 20a to 20d, since the wireless access device 20a and the wireless access device 20c transmit data wirelessly to the other wireless access devices 20, the wireless access device 20a and the wireless access device 20c. Is referred to as a wireless relay device in the wireless access device 20.

FIG. 2 is a functional block diagram of the wireless access device.
As shown in this figure, the wireless access device 20 includes a wired reception unit 201 that receives transmission data from other devices connected via a wired network, and data to other devices connected via the wired network. Wired transmitting unit 202 for transmitting, modulating unit 203 for modulating the received signal, transmitting unit 204 for amplifying the signal, distributor 205 for distributing the received signal, receiving unit 206 for receiving the signal, demodulating unit for demodulating the signal 207. Further, the wireless access device 20 includes a modulation / demodulation control unit 208 that changes the modulation scheme according to the state of the transmission path, a transmission / reception state deterioration determination unit 209 that determines whether or not the data transmission / reception state of the wireless access device 20 has deteriorated, A timeout extension requesting unit 210 for sending a timeout extension request for requesting extension of timeout time in data transmission to the monitoring apparatus 10 when the transmission / reception status degradation judging unit 209 determines that there is degradation of the data transmission / reception situation; And an antenna 211 for transmitting signals.

FIG. 3 is a functional block diagram of the monitoring device.
As shown in this figure, the monitoring device 10 includes a communication unit 101 that communicates with a wireless access device 20 connected via a wired network, a control unit 102 that controls each processing unit of the monitoring device 10, and a data transmission time. A time-out counter 103 that measures a time-out time, a time-out time changing unit 104 that performs processing for changing the time-out time, and a database 105 that holds the IP address of each wireless access device 20 are provided.

In the communication system according to the present embodiment, the wireless access device 20 (wireless relay device) that has received data transmitted from the monitoring device 10 via the wired network in the wireless access device 20 transmits the received data to the wireless communication device. Is transmitted to the other wireless access device 20, the presence / absence of deterioration of the data transmission / reception status with the wireless access device 20 is determined, and when it is determined that the data transmission / reception status is deteriorated, the timeout time of data transmission is determined. An extension request is transmitted to the monitoring device 10. Then, the monitoring device 10 extends the timeout time in data transmission based on the reception of the request for extending the timeout time.
In the communication system according to the present embodiment, the wireless access device 20 that has received the data transmitted by the monitoring device 10 from another wireless access device 20 by wireless communication transmits / receives data to / from the wireless access device 20 that has transmitted the data. When the data transmission / reception status is determined to be degraded, a request for extending the timeout time in data transmission is transmitted to the monitoring device 10 via the wireless access device 20 that transmitted the data. .
With such a process, the communication system according to the present embodiment performs a process of improving the reliability of data transmission using the SV line when the data communication is deteriorated due to fading.

  Note that fading refers to a phenomenon in wireless communication in which the wavelengths of radio waves that arrive at a time difference interfere with each other and affect the strength of the radio level on the receiving side. As a result, an environment in which data cannot be normally received by the receiving device occurs.

FIG. 4 is a sequence diagram showing a processing flow of the communication system.
Next, details of processing of each device in the communication system will be described.
In the present embodiment, a state in which fading has not occurred is assumed to be normal, and a state in which fading has occurred and the line has deteriorated is assumed to be abnormal. However, since the operations at normal time and abnormality are different, each process will be described.
First, in normal operation, the monitoring device 10 stores the IP addresses of the wireless access devices 20a to 20d in the database 105 in advance, and designates the wireless access device 20 as a data transmission target via the interface by a user or the like. When the designation of data to be transmitted using the SV line is accepted, the control unit 102 reads the IP address and data (firmware) of the wireless access device 20. Then, the control unit 102 performs a process of transmitting firmware data read from the database to the IP address read from the database by using a TFTP (Trivial File Transfer Protocol) protocol using the SV line (step S101). . In the present embodiment, it is assumed that this destination IP address is the IP address of the wireless access device 20b. When transmitting the firmware data to the wireless access device 20b, the monitoring device 10 first transmits the firmware data via the directly connected wireless access device 20a. The monitoring device 10 transmits the firmware data by dividing it into block units.

  In the wireless access device 20a, when the data transmitted from the monitoring device 10 is received by the wired reception unit 201, the modulation unit 203 modulates the signal based on the control of the modulation / demodulation control unit 208, and the transmission unit 204 is a wireless destination. The access device 20b is determined based on the IP address, and firmware data is sequentially transmitted in block units via the distributor 205 by wireless communication using the SV line (step S102). Then, by the wireless communication, the receiving unit 206 of the wireless access device 20b receives the firmware data. Here, the reception unit 206 of the wireless access device 20b sequentially receives firmware data in units of blocks, but each time the firmware data divided in units of blocks is received, a reception response (ACK) is sent to the wireless access device. It transmits to the monitoring apparatus 10 via 20a (step S103). Here, the wireless access device 20a and the transmission / reception state degradation determination unit 209 of the wireless access device 20b detect the reception level in the wireless communication between the wireless access device 20a and the wireless access device 20b, respectively, and determine whether or not fading has occurred. (Step S104). Now, it is assumed that the transmission / reception status degradation determination unit 209 of each of the wireless access device 20a and the wireless access device 20b determines that no fading has occurred. When the reception unit 206 of the wireless access device 20b receives the firmware data divided in units of all blocks, the reception unit 206 transmits a download completion notification (step S105).

  When receiving the download completion notification via the wireless access device 20a, the control unit 102 of the monitoring device 10 transmits reset instruction information to the wireless access device 20b via the wireless access device 20a (step S106). This reset instruction information is transferred from the wireless access device 20a to the wireless access device 20b by wireless communication (step S107). When the wireless access device 20b receives the reset instruction information, the wireless access device 20b rewrites the currently registered firmware data using the previously received firmware data, and restarts (step S108). Thereby, the firmware update process of the wireless access device 20a is completed. Thus, the normal process is completed.

Next, the operation at the time of abnormality will be described.
In the determination in step S104 described above, when the transmission / reception state degradation determination unit 209 of either or both of the wireless access device 20a and the wireless access device 20b determines that fading has occurred, it has determined that fading has occurred. The transmitting unit 204 of the wireless access device 20a and the receiving unit 206 of the wireless access device 20b operate the AMR function to change the signal modulation method to a lower rate method (step S109). As a result, the line capacity to be transmitted by the main signal in the radio communication between the radio access apparatus 20a and the radio access apparatus 20b is secured, and control is performed to reduce the line capacity of the SV line as much as possible. Then, the start of operation of the AMR function is detected by the timeout extension request unit 210 of the wireless access device 20a or the wireless access device 20b. Then, the timeout extension requesting unit 210 of the wireless access device 20a or the wireless access device 20b transmits information notifying the decrease of the SV line capacity to the monitoring device 10 (step S110). Note that the reception level lowering time due to fading is generally about several seconds to 90 seconds, and thereafter the reception level recovers.

  Next, when the monitoring device 10 receives the notification of the decrease in the SV line capacity, the control unit 102 causes the timeout time changing unit 104 to avoid an abnormality in data communication using the SV line due to the decrease in the SV line capacity. Outputs a command signal. Then, the time-out time changing unit 104 rewrites the time-out time threshold stored in the time-out counter 103 to a time-out time threshold longer than the current time (step S111). As a result, the timeout counter 103 performs a process of determining a timeout when the control unit 102 transmits data and the ACK is not returned from the radio access device 20, using a long timeout period. As a result, even if the SV line capacity is reduced, the probability of avoiding the inability to perform data communication due to timeout increases.

  When the transmission / reception state degradation determination unit 209 of the radio access device 20a or the radio access device 20b determines that fading has occurred and has again detected that fading has not occurred, the AMR function performs signal processing. The modulation method is changed to a higher rate method (higher speed communication is possible) (step S112). As a result, the capacity of the SV line increases to the normal capacity. The timeout extension request unit 210 of the wireless access device 20a or the wireless access device 20b notifies the monitoring device 10 of an increase in the SV line capacity when the signal modulation method is changed to a higher rate method by the AMR function. Information (notification of improvement in data transmission / reception status) is transmitted (step S113).

  Next, when the monitoring device 10 receives the notification of the increase in the SV line capacity, the control unit 102 notifies the timeout time changing unit 104 of the recovery of the state of data communication using the SV line due to the increase in the SV line capacity. Output a signal. Then, the time-out time changing unit 104 rewrites the time-out time threshold stored in the time-out counter 103 to the original short time-out time threshold (step S114). Thereafter, when the transmission of data is completed between the monitoring device 10 and the wireless access device 20, the processing of steps S105 to 108 described above is performed.

  As described above, according to each process in the above-described communication system, the wireless access device 20 (wireless relay device) connected to the monitoring device 10 through a wired network or the wireless access that receives data from other wireless access devices 20 by wireless communication. When the device 20 detects fading of wireless communication with the wireless communication partner, the device 20 requests the monitoring device 10 that is the data transmission source to extend the timeout time. Thereby, even if the line capacity of the SV line in the wireless communication based on the operation of the AMR function is reduced, it is possible to improve the accuracy of maintaining the data communication through the SV line.

FIG. 5 is a second block diagram showing the configuration of the communication system.
In the example described above, an example in which the wireless access devices 20 are connected in series has been described. However, as illustrated in FIG. 5, a plurality of wireless accesses are made to the wireless access device 20a connected to the monitoring device 10 via a wired network. You may make it comprise a communication system so that apparatus 20b-d may be directly connected by radio | wireless communication.

Each of the above devices has a computer system inside. Each process described above is stored in a computer-readable recording medium in the form of a program, and the above process is performed by the computer reading and executing the program. Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.
The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

10 ... Monitoring devices 20a to 20d ... Wireless access device 201 ... Wired reception unit 202 ... Wired transmission unit 203 ... Modulation unit 204 ... Transmission unit (wireless communication unit)
205: Distributor (wireless communication unit)
206... Reception unit (wireless communication unit)
207 ... Demodulation unit 208 ... Modulation / demodulation control unit 209 ... Transmission / reception state deterioration determination unit (first transmission / reception state deterioration determination unit, second transmission / reception state deterioration determination unit)
210 ... Time-out extension request part (first time-out extension request part, first time-out extension request part)
211 ... Antenna 101 ... Communication unit 102 ... Control unit 103 ... Timeout counter 104 ... Timeout time changing unit 105 ... Database

Claims (7)

A communication system comprising a data transmission device and a wireless relay device,
The wireless relay device is
A wireless communication unit that transmits data transmitted from the data transmission device and received via a wired network to a wireless access device by wireless communication;
A first transmission / reception state deterioration determining unit that determines whether or not the data transmission / reception state of the wireless access device has deteriorated;
A first time-out extension requesting unit for transmitting a time-out extension request for data transmission to the data transmitting device when it is determined by the first transmission / reception state deterioration determining unit that the data transmission / reception state is deteriorated; Prepared,
The data transmitting device is
A communication system, comprising: a timeout time changing unit that extends a timeout time in the transmission of the data based on reception of the request for extending the timeout time. The wireless access device is
A second transmission / reception situation deterioration determining unit that determines whether or not the data transmission / reception situation has deteriorated with the wireless relay device;
A second time-out for transmitting a request for extending a time-out period in the data transmission to the data transmission device via the wireless relay device when the second transmission / reception status degradation determination unit determines that the data transmission / reception status is deteriorated An extension request section;
The communication system according to claim 1, further comprising: The first transmission / reception state deterioration determining unit determines whether or not fading has occurred, and determines that the data transmission state has deteriorated when determining that the fading has occurred. The communication system according to 1. The second transmission / reception state deterioration determining unit determines whether or not fading has occurred, and determines that the data transmission state has deteriorated when it is determined that fading has occurred. The communication system according to 1. The time-out time changing unit of the data transmitting device changes the extended time-out time to a predetermined initial value when the data transmission / reception status improvement notification is received from either the wireless relay device or the wireless access device. The communication system according to any one of claims 1 to 4, wherein: A communication method in a communication system including a data transmission device and a wireless relay device,
The wireless communication unit of the wireless relay device transmits data received from the data transmission device and received via the wired network to the wireless access device by wireless communication,
The first transmission / reception status degradation determining unit of the wireless relay device determines whether or not the data transmission / reception status is degraded with the radio access device;
When the first timeout extension requesting unit of the wireless relay device determines that the data transmission / reception status is deteriorated in the first transmission / reception status deterioration determining unit, the data transmission request for extension of timeout time in the data transmission is sent. To the device,
The communication method, wherein the time-out time changing unit of the data transmitting device extends the time-out time in the data transmission based on reception of the time-out time extension request. A second transmission / reception status degradation determination unit of the wireless access device determines whether data transmission / reception status with the wireless relay device is degraded;
When the second timeout extension requesting unit of the wireless access device determines that the data transmission / reception status is deteriorated in the second transmission / reception status deterioration determining unit, the wireless relay relays a request for extending the timeout time in the data transmission. The communication method according to claim 7, wherein the data is transmitted to the data transmission device via the device.

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