JP5150545B2 - Communication control device and communication control method - Google Patents

Description

  The present invention relates to a communication control apparatus and a communication control method for performing communication control in xDSL (Digital Subscriber Line) communication.

  Conventionally, when a communication control device such as a modem installed in a user's home communicates with a station side device (for example, VDSL (VDSL aggregation device in the case of Very High Bitrate Digital Subscriber Line)) via a communication line by xDSL. A training process is performed as an initial procedure for starting communication. In the training process, when the modem on the user's home side is turned on, the control information is communicated between the modem and the station side device, depending on the electrical characteristics of xDSL communication, the noise level of the communication line, etc. Thus, the optimum communication parameters are determined and handshaking is executed. In such training processing, for example, a signal-to-noise ratio (SNR) is measured for each frequency band corresponding to the subchannel divided between the modem and the station-side device, and depending on the measurement result. Thus, the allocation of the frequency and the number of bits allocated to the subcarriers that are subcarriers is determined. In general, such a training process requires several tens of seconds to several minutes, and any user communication cannot be performed during the training process.

  Here, the modem and the station-side device communicate at a communication speed based on the determined communication parameter, but the communication state of the communication line may change due to an external factor after the communication is started. For example, there may be a situation in which noise occurs or increases on the communication line and bit errors frequently occur. Patent Document 1 discloses an ADSL modem that optimizes a communication speed by restarting and performing a training process again when the communication speed decreases after the start of communication. Further, in Non-Patent Documents 1 to 3, if the SNR measured within a certain time decreases so as to fall below the lower reference value, the SNR is increased by reducing the communication speed by reducing the number of bits allocated to the subcarrier. If it increases to exceed the upper limit reference value, the SRA (Seamless Rate Adaptation) function for controlling to increase the communication speed and decrease the SNR by increasing the number of bits allocated to the subcarrier, An SOS function for controlling the communication speed to drop immediately when a decrease (abrupt increase in noise) is detected is described.

JP 2003-264603 A

“ITU-T Recommendation G.993.2 Amenment 3”, TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU, August 2008 “ITU-T Recommendation G.993.2”, TELECOMMUNICATION STANDARDIZATION SECTION OF ITU, February 2006 “ITU-T Recommendation G.994.1”, TELECOMMUNICATION STANDARDIZATION SECTION OF ITU, May 2003

  However, the SRA function and the SOS function in Non-Patent Documents 1 to 3 described above are functions that operate after the training process. Therefore, by the training process which is the initial procedure of the link probability, it is possible to change the communication speed according to the increase / decrease of the SNR in the frequency band determined to be used, and maintain the SNR margin for maintaining the communication quality above a certain level. The unused frequency band determined not to be used by the training process cannot be used for communication until the training process is executed again after the link is established. In other words, even when there is a frequency band in which the SNR is small and determined as an unused frequency band when the training process is performed, and thereafter the SNR increases and communication is possible, such an unused frequency is obtained by the SRA function or the SOS function. Bands cannot be used for communication. In order to bring such an unused frequency band into a communication state, it is necessary to perform training processing again. On the other hand, the technique described in Patent Document 1 performs the training process again when the communication speed is below a certain level. For example, when the situation of the external factor is deteriorated, the communication speed is reduced. Although it is not possible to improve the training, it is considered that the operation of the training process that makes it impossible for the user to communicate arbitrarily occurs frequently.

  The present invention has been made in view of such a situation, and provides a communication control device and a communication control method capable of appropriately performing training processing when an improvement in communication speed can be expected.

  In order to solve the above-described problems, the present invention is a communication control device that controls the communication speed between a terminal device and a station-side device connected via a communication line, and measures the communication state of the communication line. A training processing unit for performing training processing for determining whether to use for communication between the terminal device and the station-side device for each frequency band of the subchannel in the communication line based on the measured communication state; An unused frequency band storage unit that stores information indicating an unused frequency band that is determined not to be used for communication by the training processing unit, and a threshold of a signal-to-noise ratio that can use the frequency band for communication is Signal-to-noise ratio threshold storage unit stored in advance, signal-to-noise ratio measurement unit for measuring signal-to-noise ratio in unused frequency band stored in unused frequency band storage unit, and noise-to-noise measurement Compare the signal-to-noise ratio measured by the signal-to-noise ratio threshold stored in the signal-to-noise ratio threshold storage unit and determine whether the measured signal-to-noise ratio exceeds the signal-to-noise ratio threshold. If the signal-to-noise ratio determination unit and the signal-to-noise ratio determination unit determine that the measured signal-to-noise ratio exceeds the threshold of the signal-to-noise ratio, communication in the unused frequency band is possible. A warning information generation unit that generates warning information indicating that there is a warning information output unit that outputs warning information generated by the warning information generation unit is provided.

  The present invention further includes a retraining request input unit that receives an input of retraining request information corresponding to the warning information output by the warning information output unit, and the training processing unit stores the retraining request information in the retraining request input unit. When input, the training process is performed.

  In the present invention, the signal-to-noise ratio measured by the signal-to-noise ratio measuring unit for a predetermined time after the warning information is generated by the warning information generating unit A training process is performed when the threshold value of the noise ratio is exceeded.

  The present invention further includes a signal determination unit that determines whether or not a frequency band that can be communicated in a communication line is a no-signal state, and the warning information generation unit includes a signal pair measured by the anti-noise ratio measurement unit. Warning information is generated when the noise ratio exceeds a signal-to-noise ratio threshold and the signal determination unit determines that the communicable frequency band is in a no-signal state.

  The present invention also provides a communication speed measuring unit that measures a communication speed of communication performed by the terminal device via a communication line, a communication speed measured by the communication speed measuring unit, and a maximum communication speed of the communication line. The communication speed determination unit that determines whether or not the communication speed exceeds the recommended communication speed and the warning information generation unit have a signal-to-noise ratio measured by the noise-to-noise ratio measurement unit. Warning information is generated when the signal-to-noise ratio threshold is exceeded and the communication speed determination unit determines that the communication speed does not exceed the recommended communication speed.

  Further, the present invention controls a communication speed between a terminal device and a station-side device connected via a communication line, and a threshold of a signal-to-noise ratio that can use the frequency band of the communication line for communication Is a communication control method of a communication control device including a signal-to-noise ratio threshold storage unit in which information is stored in advance and an unused frequency band storage unit in which information indicating an unused frequency band determined not to be used for communication is stored The training processing unit measures the communication state of the communication line, and uses it for communication between the terminal device and the station side device for each frequency band of the subchannel in the communication line based on the measured communication state. A training process for determining whether or not the information indicates an unused frequency band in an unused frequency band storage unit, and a signal-to-noise ratio measurement unit is stored in the unused frequency band storage unit. use A step of measuring a signal-to-noise ratio in the waveband; and a signal-to-noise ratio determination unit, the signal-to-noise ratio measured by the to-noise ratio measuring unit, and the signal-to-noise ratio stored in the signal-to-noise ratio threshold storage unit Comparing the ratio threshold to determine whether the measured signal-to-noise ratio exceeds the signal-to-noise ratio threshold, and the warning information generating unit is measured by the signal-to-noise ratio determining unit When it is determined that the signal-to-noise ratio exceeds the threshold of the signal-to-noise ratio, a step of generating warning information indicating that communication in an unused frequency band is possible, and a warning information output unit Outputting the generated warning information.

  As described above, according to the present invention, the communication control device measures the communication state of the communication line between the terminal device and the station side device, and based on the measured communication state, For each frequency band, training processing is performed to determine whether to use for communication between the terminal device and the station side device, and information indicating an unused frequency band determined not to be used for communication by the training processing is stored The signal-to-noise ratio in the unused frequency band stored in the unused frequency band storage unit is measured, and the measured signal-to-noise ratio is stored in advance, and the signal pair that can use the frequency band for communication is stored. When it is determined that the noise ratio threshold is exceeded, warning information indicating that communication in the unused frequency band is possible is generated. To be able to detect the state in which the communication in the determined frequency band is enabled, when the training process in this state, there is a high possibility that the communication speed is improved.

It is a block diagram which shows the structural example of the communication system by one Embodiment of this invention. It is a figure which shows the example of the frequency band determined to be used for communication by the training process by one Embodiment of this invention, and the unused frequency band determined not to be used for communication. It is a figure which shows the example of the frequency band determined to be used for communication by the training process by one Embodiment of this invention, and the unused frequency band determined not to be used for communication. It is a figure which shows the concept of the control performed by the SRA control part by one Embodiment of this invention. It is a figure which shows the communication state for every subcarrier when the communication speed by one Embodiment of this invention changes. It is a figure which shows the communication state for every subcarrier when the communication speed by one Embodiment of this invention changes. It is a figure which shows the communication state for every subcarrier when the communication speed by one Embodiment of this invention changes. It is a figure which shows the concept of the control performed by the SRA control part by one Embodiment of this invention. It is a figure which shows the change of the communication speed corresponding to the change of the conventional communication state, and the change of the communication speed corresponding to the change of the communication state using a SRA function and a SOS function. It is a flowchart which shows the operation example of the communication system by one Embodiment of this invention. It is a figure which shows the state change according to the communication control performed by the communication control apparatus by one Embodiment of this invention. It is a figure which shows the change of the noise amount of the unused frequency band by one Embodiment of this invention. It is a block diagram which shows the structural example of the communication system by one Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
<First Embodiment>
FIG. 1 is a block diagram showing a configuration of a communication system 1 according to the first embodiment of the present invention. The communication system 1 includes a terminal device 100, a communication control device 200, and a collective device 300. The terminal device 100 and the communication control device 200 are installed in the user's home. The terminal device 100 is a computer device such as a PC (personal computer) operated by a user, for example, and is connected to the communication control device 200. The communication control device 200 is a computer device that relays communication between the terminal device 100 and the collective device 300. For example, a modem can be applied. The communication control device 200 performs xDSL communication with the collective device 300. In the present embodiment, the communication control device 200 and the aggregation device 300 perform VDSL communication. The collective device 300 is a station-side device, and is connected to an external communication device through, for example, an optical fiber line. Here, although one terminal device 100 and one communication control device 200 are shown in the figure, a plurality of communication control devices 200 may be connected to the collective device 300.

The terminal device 100 is a computer device installed in a user's house, and is connected to the collective device 300 via the communication control device 200.
The communication control device 200 is a computer device that controls communication between the terminal device 100 and the aggregation device 300, and includes a communication control unit 210, an unused frequency band storage unit 220, a signal determination unit 230, and a communication speed measurement. Unit 231, communication speed determination unit 232, SNR threshold storage unit 240, SNR determination unit 241, warning information generation unit 250, warning information output unit 260, and retraining request input unit 261. As the communication control device 200, for example, a modem can be applied.

The communication control unit 210 includes a training processing unit 211, an SNR measurement unit 212, an SRA control unit 213, and an SOS control unit 214, and performs communication with the collective device 300.
The training processing unit 211 measures the communication state of the communication line such as the electrical characteristics in the xDSL communication line and the noise level of the communication line by communicating control information with the collective device 300, and sets the measured communication state. The optimum communication parameters are determined accordingly. The training processing unit 211 performs training processing for determining optimal communication parameters in this way, and executes handshaking with the aggregation device 300. Here, for example, the training processing unit 211 measures the communication state for each frequency band corresponding to a predetermined sub-channel of the communication line, and whether or not the measured communication state exceeds a predetermined communication quality threshold value. It is determined that the frequency band of the subchannel exceeding the communication quality threshold is used for communication between the terminal device 100 and the station side device 300. In addition, it is determined that the frequency band of the subchannel whose communication state does not satisfy the defined communication quality threshold is not used for communication. The training processing unit 211 stores information indicating a frequency band determined not to be used for communication in the unused frequency band storage unit 220 as an unused frequency band.

  2 and 3 are diagrams showing examples of frequency bands determined to be used for communication and unused frequency bands determined not to be used for communication by the training process performed as described above. For example, in VDSL, links between a plurality of US (UpStream) (US1 to 3) and a plurality of DS (DownStream) (DS1 to 3) are determined in advance according to the frequency band. When it is determined that all the subchannels are used by the training processing performed by the training processing unit 211, as shown in FIG. 2, it corresponds to all the subchannels of all the links of US1 to US3 and DS1 to DS3. The frequency band is used for communication. On the other hand, as shown in FIG. 3, if the communication quality of the frequency band indicated by the symbol a in US3 is equal to or lower than a predetermined threshold, the frequency band in that area is determined to be an unused area by the training processing unit 211. Is done. The training processing unit 211 stores information indicating the frequency band indicated by the symbol a in the unused frequency band storage unit 220 as an unused frequency band.

  The training processing unit 211 performs automatic retraining processing when the automatic retraining setting information is ON based on the automatic retraining setting information input by the user and stored in the storage area of the training processing unit 211. In the automatic retraining process, an unused frequency measured by the SNR measurement unit 212 for a certain time (T2) stored in advance in its own storage area after the warning information is generated by the warning information generation unit 250 described later. When the SNR of the band exceeds the SNR threshold value stored in the SNR threshold value storage unit 240, training processing is performed. The training processing unit 211 does not perform the automatic retraining process when the automatic retraining setting information is OFF.

The SNR measurement unit 212 measures the SNR for each frequency band corresponding to the subchannel defined in the communication line with the aggregation device 300.
The SRA control unit 213 controls the SRA function in VDSL. The SRA function increases the communication speed of the communication unit 220 if the SNR measured within a predetermined time by the SNR measurement unit 212 increases beyond a predetermined SNR upper limit reference value, and sets a predetermined SNR lower limit. If it is below the reference value, the communication speed of the communication unit 220 is controlled to be lowered. Here, increase / decrease in the communication speed can be controlled by changing the number of symbols per unit time, for example.

  For example, FIG. 4 is a diagram illustrating a concept of control performed by the SRA control unit 213 when the SNR measured by the SNR measurement unit 212 decreases and the amount of noise increases. In the figure, the upper part indicates that the SNR is larger and the amount of noise is smaller, and the lower part indicates that the SNR is smaller and the amount of noise is larger. For example, when the SNR is at the point indicated by the symbol a, the SNR margin exceeding the SNR lower limit reference value can be maintained. The SNR margin is a difference between a lower limit reference value for performing communication maintaining a predetermined communication quality and an SNR exceeding the lower limit reference value, and is more than a certain value (for example, 1 dB) for stable communication. It is desirable to maintain the SNR margin. For example, when the SNR decreases from the point indicated by the symbol a toward the point indicated by the symbol b due to an external factor such as an increase in the amount of noise, the SNR measurement unit 212 measures the change in the SNR. In this case, when the SRA control unit 213 determines that the SNR of the code b below the SNR lower limit reference value has continued for a predetermined time (for example, 5 seconds), the communication speed is reduced. As a result, the SNR increases from the code c toward the code d.

  For example, FIGS. 5-7 is a figure which shows the communication state for every subcarrier (for example, 4 kHz) when a communication speed changes in this way. In these figures, the amount of information (bits) that can be output to each subcarrier is indicated by the density of horizontal lines, and the greater the amount of horizontal lines, the greater the amount of information that can be output by that subcarrier. Yes. On the other hand, the smaller the amount of horizontal lines, the smaller the amount of information that can be output. For example, as described in FIG. 2, when frequency bands corresponding to all subchannels corresponding to US3 are usable, information can be output to all subcarriers as shown in FIG. it can. On the other hand, as shown in FIG. 3, when it is determined at the time of training processing that the SNR determined in the subchannel of a specific frequency band among the subchannels corresponding to US3 cannot be secured, the subchannel is supported. The frequency band to be used is determined as an unused frequency band, and no output is performed as indicated by reference symbol c in FIG. Further, in such a case, even in the subcarriers of other codes a and b near the frequency band where the SNR cannot be secured, the influence of external factors is larger than the communication state shown in FIG. The amount of information that can be output is less than that shown in FIG. 5, and the communication speed decreases. When an external factor such as noise decreases from the communication state shown in FIG. 6 and the SRA control unit 213 operates and the SNR increases, the amount of information that can be output to each subcarrier increases as shown in FIG. In this case, it is considered that information can be output because the noise also decreases in the unused frequency band indicated by the symbol c, and the communication speed can be further increased. However, depending on the function of the SRA control unit 213, such unused frequency band can be output. Information cannot be output to the used frequency band. Eventually, in order to output information in the unused frequency band indicated by the symbol c and effectively increase the communication speed using the frequency band, it is necessary to perform training again.

  FIG. 8 is a diagram illustrating a concept of control performed by the SRA control unit 213 when the SNR measured by the SNR measurement unit 212 increases and the noise amount decreases. For example, the SNR measuring unit 212 measures that the SNR increases toward the code b due to an external factor from the point indicated by the code a and the noise amount decreases. In this case, if the SRA control unit 213 determines that the SNR of the code b below the SNR upper limit reference value has continued for a predetermined time (for example, 5 seconds), the communication speed is increased. As a result, the SNR decreases from the code c toward the code d.

  Returning to FIG. 1, the SOS control unit 214 controls communication so as to immediately decrease the communication speed when detecting a rapid decrease in SNR. The SOS operates according to user settings, for example, when a plurality of communication errors are detected within a certain period of time, or when there is a change in SNR exceeding a threshold value within a certain period of time. To reduce the communication speed. In other words, SRA is a function that changes the communication speed in response to a gradual change in communication status over time, such as 5 seconds, while SOS prevents errors in response to sudden changes in external factors. Therefore, it is a function that quickly changes the communication rate to lower the communication speed. For example, when the noise level suddenly increases, an error may also occur in the communication channel, so that even a parameter for changing the communication speed may not be transmitted and received. Therefore, the communication speed can be quickly reduced when such a sudden external factor change occurs.

  FIG. 9 is a diagram illustrating a change in communication speed corresponding to a change in conventional communication state and a change in communication speed corresponding to a change in communication state using the SRA function and the SOS function. As shown in FIG. 9 (a), conventionally, when an increase in noise or the like occurs and communication quality determined due to frequent occurrence of errors or the like cannot be maintained, link disconnection occurs, and 1 to 5 minutes. After such retraining, communication is resumed at the reduced communication speed. As shown in FIG. 9B, when the SRA function and the SOS function are used, the communication speed is decreased instantaneously by the SOS function when noise increases, and then the communication speed is gradually increased by the SRA function according to the communication state. As a result, the communication connection state can be maintained without disconnecting the link even when the noise suddenly increases.

Returning to FIG. 1, the unused frequency band storage unit 220 stores information indicating an unused frequency band that is determined not to be used for communication by the training processing unit 211.
The signal determination unit 230 monitors whether or not communication with the aggregation device 300 is performed by the communication control unit 210, and the frequency band in which communication is possible on the communication line is in a no-signal state for a predetermined time. And the determination result is output to the warning information generation unit 250.

The communication speed measurement unit 231 measures the communication speed of communication performed with the aggregation device 300 by the communication control unit 210.
The communication speed determination unit 232 compares the communication speed measured by the communication speed measurement unit 231 with a recommended communication speed that is determined in advance according to the maximum communication speed of the communication line and stored in its own storage area. It is determined whether the communication speed measured by the measurement unit 231 exceeds the recommended communication speed, and the determination result is output to the warning information generation unit 250. The recommended communication speed may be set by an input from the user, or may be set and stored in advance. For example, the recommended communication speed is set in advance to a value 10 Mbps lower than the maximum communication speed. For example, if the maximum communication speed is 100 Mbps, the recommended communication speed is set to 90 Mbps.

The SNR threshold storage unit 240 stores in advance an SNR threshold that can use a frequency band for communication.
The SNR determination unit 241 compares the SNR measured by the SNR measurement unit 212 and the SNR threshold stored in the SNR threshold storage unit 240, and the SNR measured by the SNR measurement unit 212 is compared with the SNR threshold storage unit 240. It is determined whether or not the threshold value of the SNR stored in is exceeded, and the determination result is output to the warning information generation unit 250.

  The warning information generation unit 250 generates warning information when the information input satisfies a predetermined condition for a predetermined time (T1) stored in advance in its own storage area. For example, when the SNR determination unit 241 determines that the SNR measured by the SNR measurement unit 212 exceeds the SNR threshold stored in the SNR threshold storage unit 240, the warning information generation unit 250 Warning information indicating that communication is possible is generated. This is because communication in an unused frequency band is possible in this case, and it is considered that re-training can effectively use the frequency band and increase the communication speed. Further, the warning information generation unit 250 may generate the warning information on the condition that the signal determination unit 230 determines that the frequency band that can be communicated on the communication line is a no-signal state. That is, if the training process is performed when the communication line is in a communication state, a link disconnection occurs during communication, which may cause an error or stress on the user. Further, the warning information generation unit 250 generates the warning information on the condition that the communication speed determination unit 232 determines that the communication speed measured by the communication speed measurement unit 231 does not exceed the recommended communication speed. Anyway. That is, when the communication speed does not exceed the recommended communication speed, there is a high possibility that the communication speed is improved by retraining. Further, it is possible to prevent unnecessary retraining when a certain communication speed (recommended communication speed) is secured.

The warning information output unit 260 outputs the warning information generated by the warning information generation unit 250. The warning information output unit 260 may be, for example, a speaker that outputs a warning sound, a lamp or LED (Light Emitting Diode) that gives a warning by emitting light, or a display that displays warning characters. .
The retraining request input unit 261 accepts input of retraining request information from the user in accordance with the warning information output by the warning information output unit 260. For the retraining request input unit 261, for example, a button pressed by the user can be applied.

Next, an operation example of the communication system 1 according to the present embodiment will be described. FIG. 10 is a flowchart illustrating an operation example of communication control performed by the communication control apparatus 200 of the present embodiment.
Here, training processing is performed in advance by the training processing unit 211, information indicating an unused frequency band is stored in the unused frequency band storage unit 220, and communication with the collective device 300 is started by the communication control unit 210. Suppose that The SNR measurement unit 212 starts SNR measurement processing in communication performed by the communication control unit 210 with the aggregation device 300 (step S1). When the external factor decreases and the SNR increases, the SRA control unit 213 operates and improves the communication speed (step S2).

  The warning information generation unit 250 determines whether or not the determination results input from the SNR determination unit 241, the signal determination unit 230, and the communication speed determination unit 232 satisfy a predetermined condition for a predetermined time (T1). judge. In other words, the warning information generation unit 250 has a communication speed after the SRA control unit 213 operates with a recommended communication speed when the SNR threshold is equal to or less than the measured value of the SNR, the no-signal state continues for a certain period of time. It is determined whether or not the speed is below (step S3).

  The warning information generation unit 250 determines that the determination results input from the SNR determination unit 241, the signal determination unit 230, and the communication speed determination unit 232 do not satisfy the predetermined condition for a certain time (T1). If (step S3: NO), the process is terminated. On the other hand, if it determines with satisfy | filling the defined conditions (step S3: YES), the warning information output part 260 will output warning information (step S4). When a retraining request is input to the retraining request input unit 261 according to the warning information output by the warning information output unit 260 (step S5: YES), the training processing unit 211 executes a training process (step S6). The process is terminated.

  On the other hand, no retraining request is input to the retraining request input unit 261 in step S5 (step S5: NO), and the training processing unit 211 stores the automatic retraining setting information stored in the storage area of the training processing unit 211. Is determined to be ON, and if it is determined in step S3 that the condition has been satisfied and then it has been determined that T2 seconds have passed with the condition being satisfied (step S7: YES), the training processing unit 211 performs training. Processing is performed (step S8), and the processing is terminated. On the other hand, before the elapse of T2 seconds since it is determined in step S7 that the automatic retraining setting information stored in the storage area of the training processing unit 211 is not ON or the condition is satisfied in step S3. If it is determined that the same condition is not satisfied (step S7: NO), the process is terminated without performing the training process.

  FIG. 11 is a diagram illustrating a state change according to communication control performed by the communication control apparatus 200 of the present embodiment. When the influence of external factors on the communication line decreases, the SRA control unit 213 operates (reference a). The SRA control unit 213 increases the communication speed to the extent that the communication quality does not fall below the threshold in the frequency band that is determined in advance to be used for communication in the training process (reference symbol b). Here, when the influence of the external factor of the communication line is further reduced, the SNR starts to increase (reference c). The warning information is output from the warning information output unit 260 when the time of T1 seconds has passed after the measured value of the SNR exceeds the predetermined SNR threshold value (symbol d) (symbol e). Retraining is recommended. If the automatic retraining setting information is ON, even if no retraining request is input from the user, training is performed by the training processing unit 211 at the time point (T2) after the time of T2 seconds elapses from the point D. Processing begins.

  As described above, the communication control apparatus 200 according to the present embodiment measures the SNR after the start of communication for the unused frequency band (symbol a) determined not to be used for communication in the training process, as shown in FIG. As a result, a decrease in noise (N1 → N2) is detected, and when the SNR exceeds a predetermined threshold value, the training processing unit 211 performs the retraining process. For this reason, according to the present embodiment, by outputting the warning information, it is possible to perform the retraining only when the recovery of the communication speed can be expected by the retraining. As a result, the frequency band of the communication line can be used effectively, the communication speed can be increased, and link disconnection due to unnecessary retraining during communication can be eliminated. Further, when a retraining request is input by the user according to the warning information to be output, the retraining can be performed according to the convenience of the user by performing the retraining. Even when the SNR increases, unnecessary retraining can be prevented by not generating warning information when the communication speed exceeds the recommended communication speed.

<Second Embodiment>
In the first embodiment, an example is shown in which a modem is applied as a communication control device that measures SNR of a communication line and generates warning information. However, in the second embodiment, a warning is obtained by measuring the SNR of a communication line. An example will be described in which the station side device has the function of the communication control device for generating information. FIG. 13 is a diagram showing the communication system 2 according to the present embodiment. Since the configuration of the communication system 2 is the same as that of the first embodiment, the configuration and operation different from those of the first embodiment will be described below.

  The communication system 2 includes a terminal device 100, a modem 500, and a collective device 600. The modem 500 includes a warning information output unit 560 and a retraining request input unit 561. The warning information output unit 560 outputs the warning information generated by the aggregation device 600. The retraining request input unit 561 transmits a retraining request input from the user to the aggregation device 600.

  The aggregation device 600 includes a communication control unit 610, an unused frequency band storage unit 620, a signal determination unit 630, a communication speed measurement unit 631, an SNR threshold storage unit 640, an SNR determination unit 641, and a warning information generation unit. 650. The communication control unit 610 includes a training processing unit 611, an SNR measurement unit 612, and an SRA control unit 613. When the communication control unit 610 receives a retraining request transmitted from the retraining request input unit 561, the training processing unit 611 performs a training process. When the SNR determination unit 641 determines that the SNR measured by the SNR measurement unit 612 exceeds the SNR threshold stored in the SNR threshold storage unit 640, the warning information generation unit 650 performs communication in the unused frequency band. Generate warning information indicating that it is possible.

  As described above, the administrator of the communication system according to the embodiment of the present invention enables the hardware specifications and the number of terminal devices, modems, or collective devices that use the communication system, the communication speed and communication of the communication lines connecting the respective computer devices. Depending on the distance, etc., each functional unit for measuring the SNR of the communication line and generating warning information may be arranged. For example, the warning information output unit 560 that outputs warning information in the second embodiment has a mail transmission function that transmits an email including warning information indicated by text to a predetermined mail address. The apparatus 600 may be provided. In this case, when the warning information is generated by the warning information generation unit 650, the warning information output unit 560 provided in the aggregation device 600 transmits an e-mail including the warning information with a predetermined mail address as a destination. Here, a mail address corresponding to the user of the terminal device 100 can be applied as the determined mail address.

  Note that a program for realizing the function of the processing unit in the present invention is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed to perform communication control. May be. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer system” includes a WWW system having a homepage providing environment (or display environment). The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Further, the “computer-readable recording medium” refers to a volatile memory (RAM) in a computer system that becomes a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. In addition, those holding programs for a certain period of time are also included.

  The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. 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.

DESCRIPTION OF SYMBOLS 1 Communication system 100 Terminal apparatus 200 Communication control apparatus 210 Communication control part 211 Training process part 212 SNR measurement part 213 SRA control part 214 SOS control part 220 Unused frequency band memory | storage part 230 Signal determination part 231 Communication speed measurement part 232 Communication speed determination Unit 240 SNR threshold storage unit 241 SNR determination unit 250 warning information generation unit 260 warning information output unit 261 retraining request input unit 300 aggregation device 500 modem 560 warning information output unit 561 retraining request input unit 600 aggregation device 610 communication control unit 611 Training processing unit 612 SNR measurement unit 613 SRA control unit 614 SOS control unit 620 Unused frequency band storage unit 630 Signal determination unit 631 Communication speed measurement unit 632 Communication speed determination unit 640 SNR threshold storage unit 641 SNR determination unit 650 warning information generation unit

Claims (6)

A communication control device for controlling a communication speed between a terminal device and a station-side device connected via a communication line,
Whether the communication state of the communication line is measured and, based on the measured communication state, used for communication between the terminal apparatus and the station side apparatus for each frequency band of the subchannel in the communication line A training processing unit for performing training processing to determine whether or not
An unused frequency band storage unit that stores information indicating an unused frequency band that is determined not to be used for communication by the training processing unit;
A signal-to-noise ratio threshold storage unit in which a threshold of a signal-to-noise ratio capable of using the frequency band for communication is stored in advance;
A signal-to-noise ratio measurement unit for measuring a signal-to-noise ratio in the unused frequency band stored in the unused frequency band storage unit;
The signal-to-noise ratio measured by the noise-to-noise ratio measuring unit is compared with the threshold value of the signal-to-noise ratio stored in the signal-to-noise ratio threshold storage unit, and the measured signal-to-noise ratio is A signal-to-noise ratio determination unit for determining whether or not the signal-to-noise ratio threshold is exceeded;
When the signal-to-noise ratio determination unit determines that the measured signal-to-noise ratio exceeds a threshold value of the signal-to-noise ratio, warning information indicating that communication in the unused frequency band is possible A warning information generation unit to generate,
A warning information output unit that outputs the warning information generated by the warning information generation unit;
A communication control apparatus comprising: A retraining request input unit that accepts input of retraining request information according to the warning information output by the warning information output unit;
The communication control device according to claim 1, wherein the training processing unit performs the training processing when retraining request information is input to the retraining request input unit. After the warning information is generated by the warning information generation unit, the training processing unit is configured such that the signal-to-noise ratio measured by the signal-to-noise ratio measurement unit for a predetermined time period is the signal pair. The communication control apparatus according to claim 1, wherein the training process is performed when a noise ratio threshold is exceeded. A signal determination unit that determines whether or not a frequency band in which communication is possible in the communication line is in a no-signal state;
The warning information generation unit is configured such that the signal-to-noise ratio measured by the noise-to-noise ratio measurement unit exceeds a threshold of the signal-to-noise ratio, and the frequency band in which the signal determination unit can communicate is in a no-signal state The communication control device according to any one of claims 1 to 3, wherein the warning information is generated when it is determined that the communication information is determined as follows. A communication speed measuring unit that measures a communication speed of communication performed by the terminal device via the communication line;
The communication speed measured by the communication speed measurement unit is compared with a recommended communication speed that is predetermined according to the maximum communication speed of the communication line, and it is determined whether the communication speed exceeds the recommended communication speed. A communication speed determination unit to perform,
The warning information generation unit is configured such that the signal-to-noise ratio measured by the noise-to-noise ratio measurement unit exceeds a threshold value of the signal-to-noise ratio, and the communication speed determination unit sets the communication speed to the recommended communication speed. The communication control device according to any one of claims 1 to 4, wherein the warning information is generated when it is determined not to exceed. A threshold of a signal-to-noise ratio capable of controlling the communication speed between the terminal device connected via the communication line and the station side device and using the frequency band of the communication line for communication is stored in advance. A communication control method of a communication control device comprising a signal-to-noise ratio threshold storage unit and an unused frequency band storage unit that stores information indicating the unused frequency band determined not to be used for communication,
A training processing unit measures the communication state of the communication line, and performs communication between the terminal device and the station side device for each frequency band of the subchannel in the communication line based on the measured communication state. Performing a training process for determining whether to use, and storing information indicating the unused frequency band in the unused frequency band storage unit;
A signal-to-noise ratio measurement unit measuring a signal-to-noise ratio in the unused frequency band stored in the unused frequency band storage unit;
A signal-to-noise ratio determination unit compares the signal-to-noise ratio measured by the noise-to-noise ratio measurement unit with a threshold value of the signal-to-noise ratio stored in the noise-to-noise ratio margin storage unit, and is measured. Determining whether the signal to noise ratio exceeds a threshold for the signal to noise ratio;
When the warning information generation unit determines that the measured signal-to-noise ratio exceeds the signal-to-noise ratio threshold by the signal-to-noise ratio determination unit, communication in the unused frequency band is possible. Generating warning information indicating that,
A warning information output unit outputting the warning information generated by the warning information generation unit;
A communication control method comprising:

Images