JP3678714B2 - ADSL modem and its transmission rate recovery method - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an ADSL modem having a RADSL (Rate Adaptive Digital Subscriber Line) function that lowers the transmission rate as noise increases. In particular, the present invention relates to an ADSL modem and a method for recovering the transmission rate that make it possible to increase the transmission rate of a transmission rate once lowered as noise decreases.
[0002]
[Prior art]
An ADSL (Asymmetric Digital Subscriber Line) router is disclosed in Japanese Patent Laid-Open No. 2001-111620 and a RADSL function is disclosed in Japanese Patent Laid-Open No. 2000-324198, and a subscriber line drawn for a telephone is used. ADSL is well known as a modem technology that enables high-speed communication of several hundred Kbps to several Mbps, and as a feature of ADSL, a rate adaptive (adjustable transmission rate according to line conditions such as distance and line characteristics) The RADSL function is also well known.
[0003]
With this function, a transmission rate that meets the line conditions is determined during the link-up negotiation (G.hs), and data communication is performed at the transmission rate.
Here, G. hs is an ITU-T recommendation G.3 as a negotiation standard between modems. 994.1 (G.hs: handshake procedure).
When the line condition deteriorates, a link break occurs, and the connection is made so that the transmission speed is lowered and slowed down by re-linking up.
[0004]
[Problems to be solved by the invention]
However, with the ADSL rate-adaptive function, when the deteriorated line condition is improved , link disconnection does not occur, so the transmission speed cannot be increased automatically by increasing the transmission speed. There was a problem.
Accordingly, in view of the above problems, the present invention provides an ADSL modem and a transmission rate recovery method thereof that can automatically increase the transmission rate when the deteriorated line condition is improved. For the purpose.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides an ADSL modem that performs data communication at a transmission rate that matches a line condition of the line, and a rate adaptive unit that has a procedure for connecting to the line at a transmission rate that meets the line condition. In accordance with the procedure of the rate adaptive unit , the noise level is calculated by connecting the line and disconnecting the line once connected, and calculating the noise level at a constant frequency step for the frequency band used in ADSL. When the noise level is reduced by combining the levels, the line monitoring unit for monitoring whether the increased noise level of the line has been reduced, and the noise level reduction information received from the line monitoring unit After confirming that data communication is not being performed and transmitting the line disconnection request to the connection unit and disconnecting, the transmission speed that meets the line conditions Possible to perform the reconnection time, the providing ADSL modem characterized in that it comprises a noise level slowed line disconnection request transmission unit to restore the transmission rate by the increase in the line.
[0006]
By this means, the noise level is monitored, and when the line condition is improved, it is possible to automatically increase the transmission speed and increase the transmission speed. Preferably, the line monitoring unit calculates a noise level in steps of the frequency band of 26 kHz to 1.1 MHz used in ADSL at a frequency of 4 kHz.
[0007]
This means makes it possible to calculate the noise level according to the line status.
Preferably, the line monitoring unit calculates a noise level in a certain frequency step for a part of a frequency band used in ADSL.
By this means, it is possible to reduce the processing load of the noise level calculation unit.
[0008]
Preferably, the line monitoring unit determines that the noise level is decreased when the noise level continues for a predetermined time.
By this means, in the case of instantaneous noise level reduction, since it is not useful to request circuit disconnection, circuit disconnection is not requested.
Preferably, the line monitoring unit uses a plurality of bandpass filters to calculate a noise level for a frequency band used in ADSL at a constant frequency.
[0009]
Further preferably, the line monitoring unit calculates a noise level of a frequency band used in ADSL using FFT.
By these means, easily the noise level calculated feasible to ing.
[0011]
Et al., The present invention is, in the transmission rate recovery method of ADSL modems for data communication at a transmission speed that matches the line condition of the line, a step comprising the steps of connecting to the line at a transmission speed that matches the line conditions, In accordance with the above procedure, by connecting the line, disconnecting the line once connected , calculating a noise level at a constant frequency step in the frequency band used in ADSL, and synthesizing the calculated noise level A step of obtaining a decrease in the noise level, a step of monitoring whether or not the increased noise level of the line has been decreased, and if the information on the decrease in the noise level is received, data communication is not performed. By confirming and sending a disconnection request for the line, and reconnecting at a transmission rate that meets the line conditions after disconnection , the noise level of the line is increased. And a method for recovering the transmission rate of the ADSL modem.
[0012]
By this means, similarly to the above-described invention, it is possible to monitor the noise level and automatically increase the transmission speed when the line condition is improved.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of an ADSL modem according to the present invention. As shown in the figure, the ADSL modem 20 and the personal computer 30 at the user's home are connected to the ADSL line 40. The ADSL line 40 is a line that can be connected to a network such as the Internet via a not-shown ADSL exchange (DSLAM) accommodation station.
[0014]
The personal computer 30 is a general personal computer having a LAN (Local Area Network) interface.
The ADSL modem 20 includes a rate adaptive function that adjusts the transmission speed according to the line conditions of the ADSL line 40, and is a modem that connects to the ADSL line 40 to perform data communication and connects to the personal computer 30 to perform data communication.
[0015]
The ADSL modem 20 is provided with a LAN interface unit 21, an ADSL interface unit 22, a line monitoring unit 23, and a control unit 24 as internal configurations.
The LAN interface unit 21 is connected to the personal computer 30 and the control unit 24, and includes a connection unit 21A and a data transmission unit 21B.
The connection unit 21A connects and disconnects with the personal computer 30.
[0016]
The data sending unit 21B sends the data from the personal computer 30 to the control unit 24 and sends the data from the control unit 24 to the personal computer 30.
The ADSL interface unit 22 is connected to the ADSL line 40 and the control unit 24, and includes a rate adaptive (RADSL) unit 22A, a connection unit 22B, and a data transmission unit 22C.
[0017]
The RADSL section 22A The procedure for determining the ADSL system in accordance with hs and then adjusting the transmission speed according to the line conditions such as the line length and line quality of the ADSL line 40 from the accommodation station of the ADSL exchange (DSLAM) to the user's home is included. This part has a rate adaptive function. With this function, if there is any abnormality in the ADSL line 40, such as an increase in noise, the link of the ADSL line 40 is once disconnected and the line transmission speed is set. Allows to slow down.
[0018]
The connection unit 22B connects to the ADSL line 40 according to the procedure of the RADSL unit 22A, disconnects from the ADSL line 40 once connected, and further disconnects from the ADSL line 40 in response to a disconnection request from the control unit 24. Then reconnect.
The data sending unit 22C sends data from the ADSL line 40 to the control unit 24, and sends data from the control unit 24 to the ADSL line 40.
[0019]
The line monitoring unit 23 is connected to the ADSL line 40 and the control unit 24, and includes a noise level calculation unit 23A, a noise level storage unit 23B, and an alarm generation unit 23C.
The noise level calculation unit 23A monitors the noise state of the ADSL line 40 and calculates the noise level.
The noise level storage unit 23B holds the noise level calculated by the noise level calculation unit 23A.
[0020]
The alarm generation unit 23C compares the noise level calculated by the noise level calculation unit 23A with the noise level held by the noise level storage unit 23B, and if the noise level has decreased, increases the transmission speed. Raise the alarm to be faster.
The control unit 24 includes a line disconnection request transmission unit 24A and a transmission data conversion unit 24B. The line disconnection request transmission unit 24A receives an alarm from the line monitoring unit 23, transmits a line disconnection request to the ADSL interface unit 22, and transmits data. The conversion unit 24B converts transmission / reception data of the ADSL interface unit 22 and the LAN interface unit 21.
[0021]
FIG. 2 is a block diagram showing a schematic configuration of the line monitoring unit 23 in FIG. As shown in this figure, the noise level calculation unit 23A of the line monitoring unit 23 includes a plurality of bandpass filters 230-1, 230-2,..., 230-n and an addition unit that combines the outputs of the plurality of bandpass filters. 231.
The band-pass filters 230-1, 230-2,..., 230-n input signals from the ADSL line 40 and calculate the noise level in increments of 4 kHz in the frequency band 26 kHz to 1.1 MHz used in ADSL. . In this way, the noise level can be calculated according to the line status.
[0022]
The adder 231 combines the noise levels calculated by the bandpass filters 230-1, 230-2, ..., 230-n.
Further, the noise level storage unit 23B includes a delay unit (D) 232, which is connected to the output side of the adder 231 of the noise level calculation unit 23A and holds the output of the adder 231 for a certain period of time.
[0023]
Further, the alarm generation unit 23C includes a comparison unit 233, a counter 234, and a comparison unit 235. The output of the addition unit 231 is input to the non-inverting input terminal of the comparison unit 233, and the delay is input to the inverting input terminal of the comparison unit 233. The output of the unit 232 is input.
Further, a counter 234 is connected to the output side of the comparison unit 233, and the counter 234 starts counting at the rising edge of the counter 234, ends counting at the falling edge, and clears it.
[0024]
The non-inverting input terminal of the comparison unit 235 is connected to the output side of the counter 234, and a predetermined value C0 is input to the inverting input terminal. If the count C of the comparison unit 235 is larger than the predetermined value C0, an alarm is indicated. Output high level.
FIG. 3 is a diagram illustrating the frequency bands of the plurality of bandpass filters 230-1, 230-2,..., 230-n of the noise level calculation unit 23A in FIG.
[0025]
As shown in the figure, each of the bandpass filters 230-1, 230-2,..., 230-n calculates a noise level in increments of 4 kHz in a frequency band of 26 kHz to 1.1 MHz used in ADSL, A noise spectrum of the ADSL line 40 is obtained.
FIG. 4 is a diagram for explaining output waveforms of each part of the line monitoring unit 23 in FIG. As shown in FIG. 6A, the output waveform of the adder 231 of the line monitoring unit 23 is a noise level in the frequency band 26 kHz to 1.1 MHz of the ADSL line 40.
[0026]
As shown in FIG. 5B, the output waveform of the comparison unit 233 of the line monitoring unit 23 indicates whether or not the noise level has changed. When the level is “low”, the noise level increases and “high”. The level indicates a decrease in noise level.
As shown in FIG. 5C, the count C increases with the start of the counter 234 at the rise of the comparison unit 233, and the count C of the counter 234 stops at the fall of the comparison unit 233, and the count C is cleared. The
[0027]
As shown in FIG. 4D, the comparison unit 235 compares the count C of the counter 234 with the predetermined value C0, and when the count C> the predetermined value C0, the output of the comparison unit 235 becomes the “high” level. When C <predetermined value C0, the output of the comparison unit 235 becomes the “low” level.
Thus, if the noise level continues to decrease for a certain period of time, the output of the comparison unit 235 becomes a “high” level and an alarm is generated. This is because it is not useful to request circuit disconnection in the case of an instantaneous noise level reduction.
[0028]
Instead of the bandpass filters 230-1, 230-2,..., 230-n, the FFT power spectrum may be integrated using FFT (Fast Fourier Transform).
FIG. 5 is a flowchart for explaining a series of operations of the ADSL modem 20 in FIG.
[0029]
As shown in the figure, in step S101, when the ADSL modem 20 is connected to the ADSL line 40 through the connection unit 22B, the ADSL interface unit 22 performs negotiation by the ADSL connection procedure through the RADSL unit 22A. An ADSL link is established at a transmission rate that matches the line conditions.
In step S102, after the ADLS link is established, it is confirmed whether data communication with the personal computer 30 is in progress. If data communication is in progress, the process is terminated and the end of data communication is awaited.
[0030]
In step S103, when data communication is not being performed, the line monitoring unit 23 reads the noise information from the ADSL line 40, and the frequency band 26 kHz to 1.1 MHz used in ADSL via the noise level calculation unit 23A. As an example, the noise level of the ADSL line 40 is calculated for each frequency of 4 kHz and further added to synthesize the noise level of the entire frequency band. The line monitoring unit 23 holds the synthesized noise level via the noise level storage unit 23B.
[0031]
In step S104, the line monitoring unit 23 compares the noise level held in the noise level storage unit 23B and delayed for a predetermined time via the alarm generation unit 23C with the current noise level, and whether the noise level has decreased. Always monitor whether or not. If the noise level does not decrease, the process returns to step S102, and the status of the noise level of the ADSL line 40 is continuously monitored.
[0032]
If the noise level decreases in step S105, the line monitoring unit 23 issues a line disconnection request to the control unit 24.
In step S106, when the data communication is not performed, the control unit 24 transmits a line disconnection request to the ADSL interface unit 22 via the line disconnection request transmission unit 24A. When the ADSL interface unit 22 receives a line disconnection request, the ADSL interface unit 22 performs a line disconnection process via the connection unit 22B.
[0033]
In step S107, after the link (connection) is disconnected, the ADSL interface unit 22 performs relink (connection) up via the connection unit 22B in the ADSL connection procedure with reference to the RADSL unit 22A.
By performing re-link up according to the above procedure, it is possible to perform data communication using the ADSL line 40 at a transmission rate that matches the line conditions.
[0034]
In addition, when the transmission speed becomes slow due to the deterioration of the line condition, the transmission speed does not remain low even if the line condition is recovered as in the conventional case. That is, the transmission speed can be recovered along with the recovery of the line condition.
Therefore, according to the present invention, in the ADSL line whose transmission speed changes depending on the line condition, the noise level is monitored, and data communication can be performed at the maximum transmission speed corresponding to the dynamically changing line condition.
[0035]
In the above description, the noise level calculation unit 23A of the line monitoring unit 23 calculates the noise level of the ADSL line 40 in the frequency band of 26 kHz to 1.1 MHz used in ADSL for each frequency in increments of 4 kHz. The noise level may be calculated for each frequency of 4 kHz in the frequency band region where noise is likely to occur. Thereby, it becomes possible to reduce the processing load of the noise level calculation unit 23A.
[0036]
FIG. 6 is a block diagram showing a schematic configuration in the modification of FIG. As shown in this figure, a transmission rate storage table 24C is added to the control unit 24 instead of the line monitoring unit 23 as compared with FIG. 1, and the transmission rate storage table 24C is a transmission rate transmitted from the ADSL interface unit 22. Hold.
The line disconnection request transmission unit 24A of the control unit 24 obtains an average value from a plurality of transmission rates held in the transmission rate storage table 24C, compares the average transmission rate with the current transmission rate, and compares the current transmission rate with the current transmission rate. When the speed is smaller, a circuit disconnection request is transmitted.
[0037]
FIG. 7 is a flowchart for explaining a series of operations of the ADSL modem 20 in FIG.
As shown in the figure, in step S111, when the ADSL modem 20 is connected to the ADSL line 40 through the connection unit 22B, the ADSL interface unit 22 performs negotiation by the ADSL connection procedure through the RADSL unit 22A. An ADSL link is established at a transmission rate that matches the line conditions.
[0038]
In step S112 and step S113, after the ADSL link is established, the control unit 24 performs data communication with the personal computer 30 after a specific time elapses (for example, two hours later) when the personal computer 30 is performing data communication. Double check if it is in the middle.
In step S114, when data communication is not being performed, the transmission rate determined by the RADSL unit 22A is transmitted from the ADSL interface unit 22 to the control unit 24.
[0039]
In step S115, it is determined whether or not speed comparison information to be described later is held in the transmission speed storage table 24C. If the speed comparison information is held, the process proceeds to step S121.
In step S116, when the speed comparison information is not held, the transmission speed is held in the transmission speed storage table 24C.
[0040]
In step S117, it is determined whether data of an arbitrary number, for example, 10 transmission rates is held in the transmission rate storage table 24C.
In step S118, if there is no arbitrary number of transmission rates, the line is disconnected, the process returns to step S111, the line is connected, and the above procedure is repeated.
In step S119, if there is an arbitrary number of transmission rates, an average value of the transmission rates is calculated based on the arbitrary number of data.
[0041]
In step S120, the calculated average value of the transmission rates is held in the transmission rate storage table 24C as speed comparison information, and the process returns to step S111.
In step S121, it is determined whether or not the current transmission rate is slower than the average value.
If the current transmission rate is faster than the average value in step S122, the connection is continued and the process is terminated.
[0042]
In step S123, when the current transmission rate is slower than the average value, the control unit 24 issues a line disconnection request to the ADSL interface unit 22 via the line disconnection request transmission unit 24A. The ADSL interface unit 22 that has received the line disconnection request performs a line disconnection process via the connection unit 22B.
In step S124, after the link is disconnected, re-link up is performed according to the ADSL connection procedure, and the process ends.
[0043]
Therefore, according to the present invention, in an ADSL line whose transmission speed changes depending on the line condition, the transmission speed is monitored, and data communication can be performed at the maximum transmission speed corresponding to the dynamically changing line condition.
In the above description, the noise level and transmission speed of the ADSL line 40 are monitored to cope with changes in the line conditions, but it is confirmed that data communication with the personal computer 30 is not being performed, and the line of the control unit 24 The disconnection request transmission unit 24A can periodically request the connection unit 22B of the ADSL interface unit 22 to disconnect the line, thereby realizing a transmission rate suitable for the line condition. Even when the noise level is reduced, a circuit disconnection request is made, but this can be realized with a simple configuration.
[0044]
【The invention's effect】
As described above, according to the present invention, a procedure for connecting to a line at a transmission rate that meets the line conditions is provided, and the line is connected according to the procedure, and whether or not the increased noise level of the line is reduced. When monitoring and receiving information on noise level reduction, confirm that data communication is not being performed, send a line disconnection request, and reconnect. Since the transmission rate is restored, the noise level is monitored, and when the line condition is improved, the transmission rate can be automatically increased to increase the transmission rate.
[0045]
In addition, holding multiple transmission speeds of the line, calculating the average transmission speed from the multiple transmission speeds held, comparing with the current transmission speed, the current transmission speed is slower than the average transmission speed In this case, it was confirmed that data transmission was not performed, and a transmission request that was slowed down due to an increase in the noise level of the line was restored by sending a line disconnect request and reconnecting. The transmission speed is monitored, and when the line condition is improved, it is possible to automatically increase the transmission speed to increase it.
[0046]
In addition, by confirming that data communication is not in progress and sending a connection disconnection request periodically to the connection unit to perform reconnection, the transmission speed slowed down due to an increase in the noise level of the line is recovered. Therefore, even when the noise level is reduced, a circuit disconnection request is made, but this can be realized with a simple configuration.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of an ADSL modem according to the present invention.
2 is a block diagram showing a schematic configuration of a line monitoring unit 23 in FIG. 1. FIG.
3 is a diagram showing each frequency band of a plurality of band pass filters 230-1, 230-2,..., 230-n of the noise level calculation unit 23A in FIG.
4 is a diagram for explaining output waveforms of each unit of the line monitoring unit 23 in FIG. 2; FIG.
FIG. 5 is a flowchart illustrating a series of operations of the ADSL modem 20 in FIG.
6 is a block diagram showing a schematic configuration in a modification of FIG. 1;
7 is a flowchart illustrating a series of operations of the ADSL modem 20 in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 20 ... ADSL modem 21 ... LAN interface part 21A ... Connection part 21B ... Data transmission part 22 ... ADSL interface part 22A ... RADSL part 22B ... Connection part 22C ... Data transmission part 23 ... Line monitoring part 23A ... Noise level calculation part 23B, 232 ... Noise level storage unit 23C ... Alarm generation unit 24 ... Control unit 24A ... Line disconnection request transmission unit 24B ... Transmission / reception data conversion unit 24C ... Transmission speed storage table 30 ... Personal computer 40 ... ADSL lines 230-1 to 230-n ... Band Pal filter 231 ... Adder 233, 235 ... Comparator 234 ... Counter

Claims (7)

In an ADSL modem that performs data communication at a transmission rate that matches the line conditions of the line,
A rate adaptive unit having a procedure of connecting to the line at a transmission rate that matches the line condition;
In accordance with the procedure of the rate adaptive unit, the connection unit that connects the line and disconnects the once connected line;
Whether the noise level of the frequency band used in ADSL is calculated at constant frequency increments, the noise level is reduced by synthesizing the calculated noise level, and whether the increased noise level of the line is reduced or not A line monitoring unit for monitoring
When receiving information on noise level reduction from the line monitoring unit, confirm that no data communication is being performed, send a request to disconnect the line to the connection unit, and then transmit according to the line conditions after disconnecting by causing the reconnection rate, ADSL modem characterized in that it comprises a line disconnection request transmission unit to recover the transmission speed slowed by the increase in the noise level of the line. 2. The ADSL modem according to claim 1 , wherein the line monitoring unit calculates a noise level in steps of the frequency band of 26 kHz to 1.1 MHz used in ADSL at a frequency of 4 kHz. 2. The ADSL modem according to claim 1 , wherein the line monitoring unit calculates a noise level in a certain frequency step for a part of a frequency band used in ADSL.   2. The ADSL modem according to claim 1, wherein the line monitoring unit determines that the noise level is decreased when the noise level continues for a predetermined time. 2. The ADSL modem according to claim 1 , wherein the line monitoring unit calculates a noise level at a constant frequency step in a frequency band used in ADSL by using a plurality of bandpass filters. The ADSL modem according to claim 1 , wherein the line monitoring unit calculates a noise level of a frequency band used in ADSL using FFT. In a method for recovering the transmission speed of an ADSL modem that performs data communication at a transmission speed that matches the line conditions of the line,
Comprising a step of connecting to the line at a transmission rate that meets the line conditions;
Connecting the line according to the procedure, and disconnecting the line once connected;
Calculating a noise level for a frequency band used in ADSL at constant frequency increments, and combining the calculated noise level to obtain a reduction in the noise level;
Monitoring whether the increased noise level of the line has decreased;
When receiving information on the noise level reduction, confirm that data communication is not being performed, send a disconnection request for the line, and then perform reconnection at a transmission rate that meets the line conditions. A method of recovering the transmission rate of an ADSL modem, comprising: a step of recovering a transmission rate that has become slow due to an increase in the noise level of the line.

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