JP2004235703A - Wired communication control method and wired communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wired communication control method and a wired communication apparatus which quickly recovers communication between transmission stations, if the communication between the transmission stations is interrupted by heavy change of the noise and the impedance of a communication line such in power cable communications. <P>SOLUTION: The apparatus comprises a communication parameter table 104, a modulator 105 for modulating the transmission data according to the communication parameters, a digital-analog converter 107 for converting digital transmission data to output analog transmission data to a communication line 110, an analog-digital converter 108 for converting the analog data received from the communication line 110 to generate digital reception data, a demodulator 106 for demodulating the digital reception data according to communication parameters, a counter 102 for counting the number of communication error times, a timer 103 for counting a specified time period, and a means 101 for updating the communication parameters. This means 101 updates only the communication parameters every specified time period or each time a specified number of error times reaches and the communication parameter updating fails. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wired communication control method and a wired communication device employing an ADSL system or the like, and in particular, such as a power line carrier communication device in which a communication carrier is superimposed on a power line, in which noise and impedance vary significantly between transmission stations. The present invention relates to a means for quickly recovering communication when a communication disconnection occurs.
[0002]
[Prior art]
Since various electric devices are connected to the power line, they are affected by noise generated by these electric devices, impedance of the electric devices, and the like. Therefore, a power line carrier communication device used by being connected to a power line is affected by noise and impedance of electric equipment during power line carrier communication.
[0003]
Noise generated in the power line differs depending on the electric device, and noise from the same electric device may also change depending on the time zone. The impedance differs depending on the electric device, and changes depending on the power on / off. Further, the impedance also depends on the wiring pattern of the power line.
[0004]
Since the wiring pattern of the power line is determined at the time of building, it is rarely changed one after another in a short time. However, the number of connected electric devices and the on / off status of each electric device change according to the use condition. As a result, the environment of the power line including these noises and impedances changes drastically depending on the place and time.
[0005]
In power line carrier communication, it is important to secure a stable communication path even when the communication environment changes depending on the place and time. Conventional power line communication devices generally include means for examining the environment of the power line, and optimally change communication parameters in accordance with the result of the examination, thereby establishing a stable communication path regardless of the environment of each power line. We are working to secure it.
[0006]
For example, in the case of a communication system in which multiple communication carriers are superimposed, check the frequency band where noise is occurring on the power line, superimpose communication carriers avoiding that frequency band, or reduce the amount of information transmitted in that frequency band Or modulate the carrier to improve the signal / noise ratio.
[0007]
In addition, since the environment of the power line changes depending on the place and time, the communication parameters optimally selected become less optimal as time passes.
[0008]
In order to avoid these problems, each time communication is performed, it is checked whether or not the current communication parameters are optimal, and a method of changing the communication parameters (for example, see Patent Document 1), and the frequency of occurrence of communication errors are monitored. Then, a method of changing a communication parameter when a predetermined occurrence frequency is exceeded (for example, see Patent Document 2) has been proposed.
[0009]
[Patent Document 1]
JP 2001-237904 A (pages 4 to 5, FIGS. 1 and 2)
[Patent Document 1]
JP-A-2000-165304 (page 8, FIG. 4)
[0010]
[Problems to be solved by the invention]
In the first method of examining the optimality of the current communication parameter each time communication is performed and changing the communication parameter, the overhead in the investigation / change stage reduces the overall communication speed.
[0011]
In the second method of monitoring the frequency of occurrence of communication errors and changing the communication parameters when the frequency of occurrence exceeds a predetermined frequency, if the environment of the power line is improved, no communication errors occur, so the optimal communication parameters Changes to are delayed.
[0012]
In the second method, when communication cannot be completely performed, transmission of parameters to the partner station is not established, and communication parameter updating fails. Thereafter, since normal communication is attempted using the parameters that have not been updated, overhead for the normal communication occurs until the communication parameters are updated again.
[0013]
It is an object of the present invention to provide a wired communication control method and a wired communication device for quickly restoring communication between transmission stations even when communication between transmission stations is interrupted due to severe fluctuations in noise and impedance in a communication path such as a power line. It is to provide.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a wired communication control method for performing communication while updating and optimizing communication parameters according to a change in a communication environment, wherein a predetermined period and the number of communication errors are measured during normal communication processing. Determines whether communication parameter update processing is necessary. If communication parameter update processing is not required, returns to normal communication processing. If communication parameter update processing is required due to reaching a predetermined cycle or a predetermined number of errors, only communication parameter update processing succeeds. This is repeated until the communication parameter updating process succeeds, and the wired communication control method returns to the normal communication process.
[0015]
The present invention also provides a communication parameter table for storing communication parameters, a modulator for modulating transmission data according to the communication parameters, and a digital-to-analog converter for converting modulated digital transmission data and outputting analog transmission data to a communication line. An analog-to-digital converter that receives and converts analog reception data from a communication line to generate digital reception data, a demodulator that demodulates digital reception data according to communication parameters, a counter that counts the number of communication errors, and a predetermined period. And a communication parameter updating means for updating the communication parameter, wherein the communication parameter updating means updates the communication parameter each time a predetermined cycle or a predetermined number of errors is reached and a communication parameter update failure occurs. We propose a wired communication device including:
[0016]
According to the present invention, a predetermined period and the number of communication errors are measured during the normal communication processing to determine whether or not the communication parameter updating processing is necessary. Therefore, despite the normal communication environment, every time the normal communication processing ends. The overhead caused by executing the communication parameter updating process can be reduced.
[0017]
On the other hand, when the communication parameter update fails, only the communication parameter update process is repeated until the communication parameter update process succeeds. Therefore, unnecessary normal communication process and the process of determining whether or not the communication parameter update is necessary can be omitted. In this regard, overhead can be reduced. .
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a block diagram showing an internal configuration of a power line carrier communication device which is an embodiment of a wired communication device according to the present invention.
[0019]
The power line carrier communication device 100 includes a communication parameter updating unit 101, a communication error counter 102, a timer 103, a communication parameter table 104, a modulator 105, a demodulator 106, and a digital / analog (D / A) converter 107. And an analog-to-digital (A / D) converter 108 and a coupler 109.
[0020]
Communication parameter updating means 101, communication error counter 102, timer 103, communication parameter table 104, modulator 105, and demodulator 106 can be realized by hardware or software.
[0021]
The timer 103 measures a predetermined period in which the communication parameter updating means 101 periodically determines whether or not the communication parameter needs to be updated.
[0022]
The communication error counter 102 counts the number of communication errors so that the communication parameter updating means 101 updates the communication parameters when a communication error occurs a predetermined number of times, regardless of the predetermined period measured by the timer 103.
[0023]
The communication parameter table 104 stores modulation / demodulation parameters and used frequency bands.
[0024]
The communication parameter updating unit 101 has a function of determining parameters and a function of notifying a communication partner of parameters, and updates communication parameters according to the environment of the power line 110.
[0025]
As the parameter determination function, known communication data is exchanged with the communication partner to investigate the environment of the power line, a method of determining parameters based on the result, a set of a predetermined number of parameters are stored, and errors during normal communication are stored. There is a method of updating the parameters according to the occurrence situation of.
[0026]
As a parameter notification function, there is a method of notifying a parameter to a communication partner by using a carrier modulation scheme that is most resistant to noise, such as minimizing bits allocated to a communication carrier.
[0027]
When transmitting, the modulator 105 modulates the transmission information based on the communication parameters to create digital transmission data, and sends the digital transmission data to the D / A converter 107. The D / A converter 107 converts the digital transmission data into an analog transmission signal and outputs it to the combiner 109. The coupler 109 superimposes the analog transmission signal on the power line 110 and transmits the signal.
[0028]
When receiving, the coupler 109 outputs an analog reception signal superimposed on the power line 110 to the A / D converter 108. The A / D converter 108 converts an analog reception signal into digital reception data and sends the digital reception data to the demodulator 106. The demodulator 106 demodulates the digital reception data based on the communication parameters to obtain the reception data.
[0029]
The power line carrier communication device 100 checks the demodulated received data for an error, and updates the error counter 102 when an error occurs. For detecting an error, for example, a CRC code, a BHC code, or the like is used.
[0030]
[Comparative Example 1]
FIG. 2 is a flowchart showing the relationship between normal communication processing and communication parameter update processing in a conventional power line carrier communication device.
[0031]
Step 201: Execute a normal communication process.
[0032]
Step 202: Determine whether or not to update communication parameters. If it is not time to update, the process returns to the normal communication process of step 201. When the timer 103 or the communication error counter 102 indicates that it is time to update, the communication parameter updating unit 101 proceeds to a communication parameter updating process in step 203.
[0033]
Step 203: Update communication parameters.
[0034]
After the update process, the process returns to the normal communication process of step 201 regardless of the success or failure of the update, and the process of step 201 → step 202 → step 203 is repeated.
[0035]
FIG. 3 is a time chart showing an example of a change in communication speed in a conventional power line communication device. That is, it shows a temporal transition of the communication speed between the power line communication devices. The vertical lines T0 to T6 in the figure indicate the timing at which the communication parameter update is activated after the normal communication. This is an example in which the worst communication environment in which communication disconnection occurs between the vertical line T2 and the vertical line T5 in FIG. The communication speed changes due to changes in the power line environment and optimization of communication parameters.
[0036]
In the example of FIG. 3, after the communication environment first deteriorates at the time point 301, the communication parameter update is started at the first vertical line T2, and at the time point 302, the communication parameter is optimized and the communication speed is restored. However, when the environment becomes the worst at the time point 303 and the communication is interrupted, the communication parameter update is started only at each of the vertical lines T3, T4 and T5. If the update fails at these timings, the communication is restored for a long time. do not do. In this example, optimization is not performed at least at the timing of the vertical lines T3 and T4.
[0037]
Embodiment 1
FIG. 4 is a flowchart showing the relationship between the normal communication processing and the communication parameter update processing in the power line communication device according to the present invention.
[0038]
Step 201: Execute a normal communication process.
[0039]
Step 202: Determine whether or not to update communication parameters. If it is not time to update, the process returns to the normal communication process of step 201. When the timer 103 or the communication error counter 102 indicates that it is time to update, the communication parameter updating unit 101 proceeds to the communication parameter updating process of step 204 which is a feature of the present invention.
[0040]
Step 204: Update communication parameters.
[0041]
If the update process is successful, the process returns to the normal communication process of step 201, and the process of step 201 → step 202 → step 204 is repeated.
[0042]
If the update processing has failed, only step 204 of the communication parameter update processing is repeated until the update is successful. If the communication parameter updating process is successful, the process returns to the normal communication process of step 201, and the process of step 201 → step 202 → step 204 is repeated.
[0043]
FIG. 5 is a time chart showing an example of a change in communication speed in the power line communication device according to the present invention. The change in the communication environment of the power line is the same as in the conventional example of FIG. In other words, this is an example in which the worst communication environment in which communication is disconnected occurs between the vertical line T2 and the vertical line T5 in FIG. The communication speed changes due to changes in the power line environment and optimization of communication parameters.
[0044]
In the example of FIG. 5, after the communication environment first deteriorates at the time point 301, the communication parameter update is activated at the first vertical line T2, and at the time point 302, the communication parameter is optimized and the communication speed is restored. Up to this point, it is the same as the conventional example of FIG.
[0045]
In the first embodiment, even when the environment becomes the worst at the time point 303 and the communication is interrupted, the communication parameter updating process is started without waiting for the update timing at the next vertical line T3, and the communication is recovered as such. The worst environment that causes communication interruption continues between the vertical line T2 and the vertical line T5. However, in the present invention, the communication parameter updating process is repeatedly started until the communication parameter updating process succeeds. In each case, optimal communication can be restored.
[0046]
Further, the communication speed can be returned to a practical communication speed without waiting for the timing of the vertical line T5.
[0047]
According to the first embodiment, the overhead due to the communication parameter determination process can be reduced, the communication parameters can be updated efficiently, and even if a communication break occurs, the delay due to inappropriate communication parameters in normal communication does not occur. At the point of time, the optimal communication can be quickly restored.
[0048]
Here, an example in which the present invention is applied to a power line communication device has been described, but the present invention is also effective in a wired communication device such as an ADSL system using a telephone line.
[0049]
【The invention's effect】
According to the present invention, the overhead due to the communication parameter determination processing is reduced, the communication parameters are updated efficiently, and even when a communication break occurs, a delay due to inappropriate communication parameters in the normal communication stage does not occur, and each time point is reduced. Communication can be restored quickly.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an internal configuration of a power line communication device which is an embodiment of a wired communication device according to the present invention.
FIG. 2 is a flowchart illustrating a relationship between a normal communication process and a communication parameter update process in a conventional power line communication device.
FIG. 3 is a time chart showing an example of a change in communication speed in a conventional power line communication device.
FIG. 4 is a flowchart showing a relationship between a normal communication process and a communication parameter update process in the power line communication device according to the present invention.
FIG. 5 is a time chart showing an example of a change in communication speed in the power line communication device according to the present invention.
[Explanation of symbols]
100 Wired communication device (power line communication device)
101 Communication parameter updating means 102 Communication error counter 103 Timer 104 Communication parameter table 105 Modulator 106 Demodulator 107 Digital analog (D / A) converter 108 Analog digital (A / D) converter 109 Coupler 110 Power line 201 Normal communication processing 202 Communication parameter update determination 203 Communication parameter update processing (conventional example)
204 Communication parameter update processing (the present invention)
301 Environment deterioration 302 Optimization 303 Environment deterioration (communication cutoff)
304 Optimization during environmental degradation (this invention)

Claims (2)

In a wired communication control method for performing communication while updating and optimizing communication parameters according to a change in communication environment,
Measure the predetermined period and the number of communication errors during the normal communication process to determine the necessity of the communication parameter update process,
If the communication parameter update process is unnecessary, return to the normal communication process,
If the communication parameter update process is required by reaching a predetermined cycle or a predetermined number of errors, repeat until only the communication parameter update process succeeds,
A wired communication control method, wherein, when the communication parameter updating process is successful, the process returns to the normal communication process. A communication parameter table for storing communication parameters, a modulator for modulating transmission data according to the communication parameters, a digital-to-analog converter for converting modulated digital transmission data and outputting analog transmission data to a communication line; An analog-to-digital converter that receives and converts analog reception data to generate digital reception data, a demodulator that demodulates the digital reception data according to the communication parameters, a counter that counts the number of communication errors, and measures a predetermined period. And a communication parameter updating means for updating the communication parameters,
A wired communication apparatus, wherein the communication parameter updating means includes means for updating a communication parameter each time a predetermined cycle or a predetermined number of errors is reached and a communication parameter update failure occurs.

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