JP2006033744A - Adsl modem apparatus and communication controlling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide effective data communication, by switching a stable communication capability due to a system using a FDM and a communication capability which is superior in the communication speed of downstream, due to a system that uses an echo canceller. <P>SOLUTION: A processor 20 is related to S/N ratio to a reception signal from a partner-side ADSL modem apparatus connected via a line; calculates the S/N ratio in the case of using the echo canceller and in the case of using a frequency division multiplexing (ST403); selects the use of the echo canceller or the frequency division multiplexing in the data communication followed based on the S/N ratio (ST406 and ST407); notices this selection result to the partner side ADSL modem apparatus (ST408); and conducts the data communication with the partner side ADSL modem apparatus using either system of the noticed ones (ST409). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ADSL modem apparatus and a communication control method capable of switching between a system using frequency division multiplexing and a system using an echo canceller.

  In recent years, an ADSL service that enables simultaneous use of a high-speed Internet connection service and a conventional telephone service using an existing telephone line has been rapidly spreading. In an ADSL modem necessary for providing such an ADSL service, a DMT (discrete multi tone) modulation method using a plurality of carriers (subcarriers) with a wide frequency bandwidth is employed.

  For example, G.1, which is one of ADSL standards. In 992.1 (G.dmt), a band from 25 kHz to 1.1 MHz is divided into 256 subcarriers. Index numbers (#) are assigned to the subcarriers in order from the lowest frequency. As shown in FIG. 8 (a), in general, transmission (downstream) from the center (ATU-C) on the station side to the remote (ATU-R) on the user's home side is from # 32 to # 255. Use subcarriers. Further, in transmission (upstream) from ATU-R to ATU-C, subcarriers # 7 to # 31 are used. In this method, ATU-R uses frequency division multiplexing (hereinafter referred to as “FDM (Frequency Division Multiplexing)”) in order to use the downstream communication band and the upstream communication band as independent communication channels. To do.

  On the other hand, for the purpose of increasing the downstream communication speed, as shown in FIG. 8B, a method of using subcarriers # 7 to # 255 for downstream communication is also adopted. In this method, subcarriers # 7 to # 31 are used in both ATU-C and ATU-R. In the case of this method, the ATU-R uses an echo canceller in order to eliminate wraparound of its own transmission signal. In the method using the echo canceller, the bandwidth that can be used in the downstream is wider than that in the method using the FDM, so that the downstream communication speed can be increased accordingly.

In addition, the standard G. mentioned above. In data communication using the DMT modulation method adopted in 992.1 (G.dmt), an ADSL modem apparatus that appropriately performs gain control of signal energy that may be deteriorated due to factors such as line conditions has been proposed (for example, , See Patent Document 1).
JP 2003-8536 A

  However, when communication is performed using a method using an echo canceller, if the communication environment deteriorates due to the communication distance becoming more than a certain value, the ATU-R may completely eliminate the wraparound of its own transmission signal. become unable. For this reason, there is a problem that communication itself becomes impossible because it becomes impossible to appropriately extract the received signal from the ATU-C.

  In the method using FDM, since the downstream communication band and the upstream communication band are used as independent communication channels, the communication itself is caused by the wraparound of its own transmission signal in the ATU-R. A situation that becomes impossible cannot occur.

  The present invention has been made in view of the above circumstances, and switches between stable communication capability using a method using FDM and communication capability excellent in downstream communication speed using a method using an echo canceller. An object of the present invention is to provide an ADSL modem apparatus and a communication control method capable of efficiently performing data communication.

  The present invention calculates an S / N ratio for a received signal from a partner ADSL modem apparatus connected via a line when an echo canceller is used and when frequency division multiplexing is used. Based on this S / N ratio, the use of echo canceller or frequency division multiplexing in the subsequent data communication is selected, the selection result is notified to the other party ADSL modem apparatus, and the other party is notified using one of the notified methods. Data communication is performed with an ADSL modem apparatus.

  According to the present invention, it is possible to efficiently perform data communication by switching between a stable communication capability based on a scheme using FDM and a communication capability excellent in downstream communication speed based on a scheme using an echo canceller.

  The ADSL modem apparatus according to the first aspect of the present invention has an S / N ratio for a received signal from a partner ADSL modem apparatus connected via a line, and uses an echo canceller and frequency division multiplexing A calculation means for calculating the S / N ratio in the case of being performed, a selection means for selecting use of an echo canceller or frequency division multiplexing in the subsequent data communication based on the S / N ratio, and a selection result of the selection means It adopts a configuration comprising notification means for notifying the other party ADSL modem apparatus and communication means for performing data communication with the other party ADSL modem apparatus using any of the notified methods.

  According to this configuration, the use of the echo canceller or the frequency division multiplexing in the subsequent data communication is selected based on the S / N ratio when the echo canceller is used and when the frequency division multiplexing is used. Is used to perform data communication with the partner ADSL modem apparatus. For this reason, it is possible to efficiently perform data communication by switching between a stable communication capability based on a method using frequency division multiplexing (FDM) and a communication capability excellent in downstream communication speed based on a method using an echo canceller. .

  According to a second aspect of the present invention, in the ADSL modem apparatus according to the first aspect, the selection means uses an echo canceller for the communication speed when frequency division multiplexing is used at the downstream communication speed in the ADSL service. In such a case, the frequency division multiplexing is selected when the communication speed is exceeded.

  According to this configuration, use of frequency division multiplexing is selected when the downlink communication speed when using frequency division multiplexing exceeds the communication speed when using an echo canceller. For this reason, according to the communication environment, it is possible to perform data communication by selecting a method having a higher downlink communication speed.

  According to a third aspect of the present invention, in the ADSL modem apparatus according to the first aspect, the selection means uses frequency division multiplexing when the echo canceller is used at the downstream communication speed in the ADSL service. If the communication speed exceeds the above case, the use of an echo canceller is selected.

  According to this configuration, the use of the echo canceller is selected when the downlink communication speed when the echo canceller is used exceeds the communication speed when the frequency division multiplexing is used. For this reason, according to the communication environment, it is possible to perform data communication by selecting a method having a higher downlink communication speed.

  According to a fourth aspect of the present invention, in the ADSL modem apparatus according to the third aspect, the selecting means is a prescribed value in which a communication speed when an echo canceller is used is determined in advance in an upstream communication speed in an ADSL service. If the frequency is lower than 1, a configuration for selecting the use of frequency division multiplexing is adopted.

  According to this configuration, use of frequency division multiplexing is selected when the uplink communication speed when using the echo canceller falls below a predetermined value. Therefore, even if the downlink communication speed when using an echo canceller exceeds the communication speed when using frequency division multiplexing, if the uplink communication speed cannot be secured above a certain level, frequency division multiplexing is required. Use of is selected. For this reason, it is possible to perform data communication while ensuring the communication speed in the uplink direction at a certain level or more while considering the communication speed in the downlink direction.

  According to a fifth aspect of the present invention, in the ADSL modem apparatus according to the first aspect, the ratio of the bandwidth used for uplink data communication and the bandwidth used for downlink data communication in the ADSL service is changed. The communication unit further includes a changing unit, and the notification unit notifies the partner ADSL modem apparatus of the changed bandwidth ratio, and the communication unit uses the partner bandwidth ADSL modem apparatus based on the changed bandwidth ratio. To perform data communication with each other.

  According to this configuration, by changing the ratio of the bandwidth used for the uplink data communication and the bandwidth used for the downlink data communication, the uplink direction performed with the counterpart ADSL modem apparatus Alternatively, the data communication speed in the downlink direction can be made variable. As a result, the communication speed of the uplink data communication can be increased, and therefore the data communication speed that does not cause discomfort to the user can be ensured even in the uplink data communication.

  According to a sixth aspect of the present invention, in the ADSL modem apparatus according to the fifth aspect, the changing means increases a ratio of a bandwidth used for uplink data communication according to a capacity of data to be transmitted. On the other hand, a configuration is adopted in which the ratio of the bandwidth used for downlink data communication is reduced.

  According to this configuration, the ratio of bandwidth used for uplink data communication is increased according to the capacity of data to be transmitted, while the ratio of bandwidth used for downlink data communication is decreased. . As a result, the communication speed of the uplink data communication can be increased according to the capacity of the data to be transmitted. Therefore, even in the uplink data communication, the user can respond according to the capacity of the data to be transmitted. It is possible to ensure a data communication speed that does not cause discomfort.

  According to a seventh aspect of the present invention, in the ADSL modem apparatus according to the sixth aspect, the changing means determines the capacity of the data to be transmitted according to the type of data to be transmitted.

  According to this configuration, the capacity of data to be transmitted is determined according to the type of data to be transmitted. Therefore, it is possible to determine the capacity of data to be transmitted simply by specifying the type of data to be transmitted. As a result, the ratio between the bandwidth used for uplink data communication and the bandwidth used for downlink data communication can be changed according to the type of data to be transmitted.

  In the communication control method according to the eighth aspect of the present invention, the S / N ratio with respect to the received signal from the partner ADSL modem apparatus connected via the line is used, and the case where an echo canceller is used and frequency division multiplexing is used. The S / N ratio is calculated, and the use of echo canceller or frequency division multiplexing in the subsequent data communication is selected based on the S / N ratio, and the selection result is notified to the partner ADSL modem apparatus. Data communication is performed with the counterpart ADSL modem apparatus using any of the notified methods.

  According to a ninth aspect of the present invention, in the communication control method according to the eighth aspect, in the downlink communication speed in the ADSL service, the communication speed when frequency division multiplexing is used is the communication speed when the echo canceller is used. Is selected when frequency division multiplexing is used.

  According to a tenth aspect of the present invention, in the communication control method according to the eighth aspect, the communication speed when the echo canceller is used is the communication speed when frequency division multiplexing is used in the downlink communication speed of the ADSL service. The use of an echo canceller is selected when exceeding the above.

  According to an eleventh aspect of the present invention, in the communication control method according to the tenth aspect, when the communication speed when the echo canceller is used is lower than a predetermined specified value in the upstream communication speed in the ADSL service. This selects the use of frequency division multiplexing.

  According to a twelfth aspect of the present invention, in the communication control method according to the eighth aspect, a ratio between a bandwidth used for uplink data communication and a bandwidth used for downlink data communication in the ADSL service is changed. Then, the changed bandwidth ratio is notified to the partner ADSL modem apparatus, and data communication is performed with the partner ADSL modem apparatus based on the changed bandwidth ratio.

  A thirteenth aspect of the present invention is the communication control method according to the twelfth aspect, wherein the ratio of the bandwidth used for uplink data communication is increased according to the capacity of data to be transmitted while the downlink direction is increased. The ratio of the bandwidth used for data communication is reduced.

  A fourteenth aspect of the present invention is a communication control method according to the thirteenth aspect, wherein the capacity of data to be transmitted is determined according to the type of data to be transmitted.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of a communication system on a terminal device (ATU-R) side installed in a home or the like to which the present invention is applied.

  In the communication system shown in FIG. 1, a public line network or an equivalent line network (hereinafter referred to as “line”) is connected to an ADSL modem apparatus 2 via a splitter 1, and a user terminal (PC) is connected to the ADSL modem apparatus 2. ) 3 is connected. In addition, when the user terminal 3 and the telephone 4 are used on one line, the splitter 1 is necessary. However, if the telephone 4 is not used, the splitter 1 is not necessary. It is also possible to configure the user terminal 3 to incorporate the ADSL modem apparatus 2.

  The ADSL modem apparatus 2 includes a transceiver 11 that executes ADSL communication and a host 12 that controls the overall operation including the transceiver 11. The line side end of the transceiver 11 is constituted by an analog circuit via an analog front end (hereinafter referred to as “AFE”) 13. A driver 15 is connected to the DA converter of the AFE 13 via an analog filter 14, and an analog signal amplified by the driver 15 is sent to a line via a hybrid 16. An analog signal coming from the line is received by the receiver 17 via the hybrid 16 and input to the AD conversion unit of the AFE 13 via the analog filter 18. The AFE 13 outputs the sampling data output from the AD conversion unit to the transceiver 11.

  FIG. 2 is a functional block diagram of the transceiver 11 included in the ADSL modem apparatus 2. The processor 20 has a function of executing a handshake procedure and an initialization procedure and executing communication control during data communication (show time).

  The transmission side of the transceiver 11 includes a Reed-Solomon encoding unit 21 for adding redundant bits for error checking, an interleaving unit 22 for rearranging data to enable correction for burst errors during Reed-Solomon decoding, and a trellis code A trellis encoding unit 23 that performs convolution of data by conversion, a tone ordering unit 24 that allocates the number of bits for each carrier, a constellation encoding unit 25 that allocates the phase of transmission data on constellation coordinates, and constellation encoded. The IFFT unit 26 performs inverse fast Fourier transform (hereinafter referred to as “IFFT”) on the received data.

  The receiving side of the transceiver 11 performs fast Fourier transform (hereinafter referred to as “FFT”) on the sampling data of the received signal, decodes the data from the constellation of the FFT output signal, and converts the phase on the constellation coordinates. A constellation decoding / FEQ unit 28 to be corrected, a tone deordering unit 29 for restoring data allocated to each carrier that has been tone-ordered on the transmission side, a Viterbi decoding unit 30 that performs Viterbi decoding on received data, Are composed of a deinterleave unit 31 that restores the data rearranged in (1) and a Reed-Solomon decoding unit 32 that deletes redundant bits added on the transmission side.

  The RAM 33 is a work area of the processor 20 and is used when a handshake procedure and an initialization procedure are executed. The transceiver 11 is connected to the host 12 via a host interface (I / F) 34.

  The ADSL modem apparatus 2 having such a configuration, according to the present embodiment, uses a system using FDM (hereinafter referred to as “FDM system”) according to the received signal level from the switching center apparatus (ATU-C). ) Or data communication by selecting whether to perform communication with excellent downstream communication speed by a method using an echo canceller (hereinafter referred to as “EC method”). More specifically, the S / N ratio (hereinafter referred to as “reception S / N ratio”) of the received signal in the case of the FDM system and the EC system is calculated, and one of them is calculated based on the reception S / N ratio. Select this method to perform data communication.

  FIG. 3 is a functional block diagram for explaining the echo canceller function realized by the ADSL modem apparatus 2 according to the present embodiment. When the echo canceller is used, the analog filter 14 and the analog filter 18 for dividing the frequency band shown in FIG. 1 are not necessary, and are omitted in FIG.

  As shown in the figure, the transmission signal output from the IFFT unit 26 is output to the hybrid 16 via the driver 15 that functions as a transmission amplifier. An echo canceller 41 provided in the transceiver 11 branches and takes in a transmission signal output from the IFFT unit 26. On the other hand, a reception signal obtained by synthesizing the transmission signal of the switching center apparatus (ATU-C) and the echo component of the transmission signal of itself (ATU-R) is output from the hybrid 16 to the receiver 17 functioning as a reception amplifier. A subtractor 42 is installed at the input stage of the FFT unit 27. The subtracter 42 subtracts the transmission signal of the echo canceller 41 from the output signal of the receiver 17. This subtraction result is input to the FFT unit 27 as a received signal. Thus, the echo canceller function is realized by removing the echo component of the transmission signal from the reception signal input to the receiver 17.

  Next, the operation when data communication is performed by selecting the FDM system or the EC system in the ADSL modem apparatus 2 configured as described above will be described with reference to FIG.

  In the ADSL modem apparatus 2 according to the present embodiment, the processor 20 determines the received signal level from the switching center apparatus (ATU-C) when executing the initialization procedure, and selects either the FDM system or the EC system. Select to perform data communication.

  Therefore, when data communication is performed by selecting the FDM method or the EC method, first, the processor 20 executes an initialization procedure through a handshake procedure with the ADSL modem device of the exchange station device (ATU-C). (ST401). Then, the received signal level is measured using the signal from the switching center apparatus (ATU-C) by this initialization procedure (ST402). For example, the processor 20 measures the received signal level using the REVERB signal transmitted from the switching center apparatus (ATU-C) in the initialization procedure.

  In this initialization procedure, the processor 20 establishes symbol synchronization with the ADSL modem apparatus of the switching center apparatus (ATU-C) and each carrier in parallel with the FDM system and EC system selection processes described below. Processing such as allocation of the number of bits for.

  When the received signal level is measured, processor 20 calculates a received S / N ratio in the case of the EC method and a received S / N ratio in the case of the FDM method based on the received signal level (ST403). After calculating both reception S / N ratios, it is determined whether the downstream communication speed (downstream speed) is greater (faster) in the EC system than in the FDM system (ST404).

  When the communication speed in the EC system is high, it is determined whether the upstream communication speed (upstream speed) in the EC system is higher (faster) than a predetermined value (ST405). When the upstream communication speed (upstream speed) in the case of the EC method is faster than the specified value, the processor 20 selects the EC method (ST406).

  On the other hand, when it is determined in ST404 that the communication speed in the FDM method is high, and in ST405, it is determined that the upstream communication speed (upstream speed) in the case of the EC method is slower than the specified value. In that case, the processor 20 selects the FDM system (ST407).

  For example, when the communication environment is inferior due to the communication distance being more than a certain value and the downlink speed when using the FDM method is faster than the downlink speed when using the EC method, or when the downlink speed is EC Even when the method is faster, the FDM method is selected when a sufficient communication speed cannot be secured at the uplink speed. On the other hand, when the communication environment is good because the communication distance is short, etc., and the downlink speed in the EC scheme is faster than the downlink speed in the FDM scheme, the EC scheme is selected. .

  After selecting the EC method or the FDM method in ST406 or ST407, the processor 20 determines the selection result, and the upstream bandwidth (upstream bandwidth) and the downstream bandwidth (downstream bandwidth) set in accordance with the selection. (Width) information is notified to the ADSL modem apparatus of the switching center apparatus (ATU-C) (ST408). In the process so far, the initialization procedure ends.

  When the initialization procedure is completed, the processor 20 performs data communication (Showtime) with the ADSL modem apparatus of the switching center apparatus (ATU-C) based on the selection result and bandwidth notified in ST408 (ST409). As described above, data communication is performed by the method selected in ST406 or ST407 based on the comparison result of the downlink speed (ST404) and the comparison result of the uplink speed (ST405). For this reason, it is possible to perform data communication efficiently by switching between the stable communication capability by the FDM method and the communication capability having excellent downstream communication speed by the EC method, flexibly corresponding to the communication environment.

  As described above, according to the ADSL modem apparatus 2 according to the present embodiment, the EC method or the FDM method in the subsequent data communication is selected based on the S / N ratio in the case of the EC method and the case of the FDM method, and the selection is made. Data communication is performed with the ADSL modem apparatus of the switching center apparatus (ATU-C) using the above-described method. Therefore, it is possible to efficiently perform data communication by switching between stable communication capability based on the FDM scheme and communication capability excellent in downstream communication speed based on the EC scheme.

  In the ADSL modem apparatus 2 according to the present embodiment, the FDM system is selected when the downlink communication speed in the case of the FDM system exceeds the communication speed in the case of the EC system. On the other hand, the EC method is selected when the downlink communication speed in the EC method exceeds the communication speed in the FDM method. For this reason, according to the communication environment, it is possible to perform data communication by selecting a method having a higher downlink communication speed.

  Furthermore, in the ADSL modem apparatus 2 according to the present embodiment, the FDM system is selected when the uplink communication speed in the EC system is below a predetermined value. Therefore, even if the downlink communication speed in the EC scheme is higher than the communication speed in the FDM scheme, the FDM scheme is selected when the uplink communication speed cannot be secured above a certain level. For this reason, it is possible to perform data communication while ensuring the communication speed in the uplink direction at a certain level or more while considering the communication speed in the downlink direction.

  In the above description, in the case of using the EC method or the FDM method, the frequency band used for uplink and downlink data communication is described on the premise of a generally adopted frequency band. That is, in the case of the FDM scheme, the subcarriers # 7 to # 31 are used in the uplink direction, while the subcarriers # 32 to # 255 are used in the downlink direction. In the case of the EC scheme, the uplink direction is used. In FIG. 3, the subcarriers # 7 to # 31 are used, while the subcarriers # 7 to # 255 are used in the downlink direction.

  However, in order to increase the communication speed in uplink data communication, the bandwidth ratio used for uplink and downlink data communication is variable, and data communication is performed using the changed bandwidth ratio. This is preferable as an embodiment. Specifically, the processor 20 changes the ratio between the bandwidth used for uplink data communication and the bandwidth used for downlink data communication (hereinafter referred to as “bandwidth ratio” as appropriate). Thus, the data communication speed performed between the terminal device (ATU-R) and the switching center device (ATU-C) installed in the home is variable.

  FIG. 5 and FIG. 6 are diagrams for explaining the ratio of bandwidths used for uplink and downlink data communication in ADSL modem apparatus 2 according to the present embodiment. In the figure, particularly, the case of changing the bandwidth ratio in the case of the FDM method is shown. In the figure, the horizontal axis represents frequency and the vertical axis represents amplitude.

  FIG. 5A shows a case where the ratio between the bandwidth used for uplink data communication and the bandwidth used for downlink data communication is a ratio of 1: 8, and FIG. In this example, the bandwidth ratio is 1: 4. Similarly, FIG. 6A shows a case where the bandwidth ratio is 1: 2, and FIG. 6B shows a case where the bandwidth ratio is 1: 1. .

  FIG. 5A shows a ratio between a bandwidth used for uplink data communication and a bandwidth used for downlink data communication in a general ADSL service. That is, it corresponds to general Internet access in which the downlink traffic volume is overwhelmingly larger than the uplink traffic volume.

  5 (b), 6 (a), and 6 (b) show data communication in the upstream direction rather than the bandwidth ratio in a general ADSL service in order to increase the data communication speed in the upstream direction. The ratio of the bandwidth used for is increased. In the order of the ratios shown in FIGS. 5B, 6A, and 6B, the uplink data communication speed is increased.

  It is necessary to increase the data communication speed in the uplink direction as the capacity of data transmitted from the terminal device increases. Taking FIG. 5B, FIG. 6A and FIG. 6B as examples, for example, when transmitting still image data such as a photograph from a terminal device, the bandwidth shown in FIG. A ratio is selected. Also, the bandwidth ratio shown in FIG. 6A is selected when moving image data such as video having a larger capacity than still image data is transmitted from the terminal device. Furthermore, the bandwidth ratio shown in FIG. 6B is selected when data having a larger capacity than the moving image data is transmitted from the terminal device.

  In the ADSL modem apparatus 2 according to the present embodiment, when the processor 20 executes the handshake procedure, the processor 20 determines the capacity of data to be transmitted to the exchange station apparatus (ATU-C) side, and performs uplink data communication. The ratio between the bandwidth used and the bandwidth used for downlink data communication is determined.

  In the handshake procedure, the processor 20 determines, for example, the bandwidth used for uplink data communication and the bandwidth used for downlink data communication according to the content (data capacity) preset in the apparatus body. Determine the ratio. That is, the case where the type of data to be transmitted is determined, that is, the case where the user terminal 3 to which the ADSL modem apparatus 2 is connected mainly transmits still image data is applicable. Note that the method for determining the ratio to the bandwidth is not limited to this.

  Hereinafter, the operation when ADSL modem apparatus 2 according to the present embodiment determines the ratio between the bandwidth used for uplink data communication and the bandwidth used for downlink data communication will be described with reference to FIG. I will explain.

  In the following, a case will be described in which the bandwidth ratio is determined according to the content (data capacity) preset in the apparatus main body. In particular, here, a case where the type of data to be transmitted is set will be described. In the initial state, it is assumed that the bandwidth ratio in the general ADSL service shown in FIG.

  When starting data communication with the ADSL modem apparatus of the switching center apparatus (ATU-C), first, in the ADSL modem apparatus 2 of the terminal apparatus (ATU-R) in the home, the processor 20 executes a handshake procedure. In such a handshake procedure, the processor 20 determines whether or not the type of data to be transmitted is preset in the apparatus body (ST701). Here, as the type of data to be transmitted, still image data, moving image data, and data having a larger capacity than the moving image data (hereinafter referred to as “large capacity data”) are preset in the apparatus main body. The case will be described. Note that the type of data to be specified is not limited to this.

  When the type of data to be transmitted is set in advance in the apparatus main body, the processor 20 determines which of still image data, moving image data, and large-capacity data is set (ST702 to ST704). If any data setting cannot be confirmed in ST702 to ST704, the processing of ST702 to ST704 is repeated again. If a predetermined time elapses without confirming any data setting, the process proceeds without changing the upstream data communication speed (not shown).

  If still image data is set, processor 20 sets the ratio of the bandwidth used for uplink data communication to the bandwidth used for downlink data communication to 1: 4 (ST705). ). Similarly, the bandwidth ratio is set to 1: 2 when moving image data is set (ST706), and the bandwidth ratio is set to 1: 1 when large-capacity data is set. (ST707).

  When the bandwidth ratio is set according to any of the data, processor 20 notifies the set bandwidth ratio to the ADSL modem apparatus of the switching center apparatus (ATU-C) (ST708). If it is determined in ST701 that the type of data to be transmitted is not set in advance in the apparatus main body, the ratio of the bandwidth set in the initial state (upward direction: downward direction = 1). : 8) is maintained and the setting is notified.

  After notifying the set bandwidth ratio, the processor 20 executes the above-described initialization procedure included in FIG. 4 (ST709). After completing the initialization procedure, the processor 20 communicates with the ADSL modem apparatus of the switching center apparatus (ATU-C) at the bandwidth ratio set in ST 705 to ST 707 or the default bandwidth ratio. Data communication (Showtime) is performed (ST710). Since data communication is performed at the bandwidth ratio set in ST705 to ST707 as described above, the data communication speed in the upstream direction is increased compared to the case where data communication is performed at the bandwidth ratio in a general ADSL service. Data communication can be performed.

  As described above, according to the ADSL modem apparatus 2 according to the present embodiment, by changing the ratio of the bandwidth used for the uplink data communication and the bandwidth used for the downlink data communication, The data communication speed in the uplink direction or the downlink direction performed between the terminal apparatus (ATU-R) and the exchange station apparatus (ATU-C) installed in can be made variable. As a result, the communication speed of the uplink data communication can be increased, and therefore the data communication speed that does not cause discomfort to the user can be ensured even in the uplink data communication.

  Further, according to the ADSL modem apparatus 2 according to the present embodiment, the ratio of the bandwidth used for the uplink data communication is increased according to the capacity of the data to be transmitted, while the downlink data communication is performed. The proportion of bandwidth used is reduced. As a result, the communication speed of the uplink data communication can be increased according to the capacity of the data to be transmitted. Therefore, even in the uplink data communication, the user can respond according to the capacity of the data to be transmitted. It is possible to ensure a data communication speed that does not cause discomfort.

  In particular, in the ADSL modem apparatus 2 according to the present embodiment, the capacity of data to be transmitted is determined according to the type of data to be transmitted. Therefore, it is possible to determine the capacity of data to be transmitted simply by setting the type of data to be transmitted. As a result, according to the type of data to be transmitted, the bandwidth ratio used for uplink data communication can be increased, while the bandwidth ratio used for downlink data communication can be decreased.

  In the above description, the case where the bandwidth ratio is changed in the case of the FDM method is described as an example. However, the present invention is not limited to this, and the bandwidth ratio may be changed in the EC method. In this case, it is possible to set the bandwidth used for the uplink data communication widely while ensuring the bandwidth used for the downlink data communication constant without reducing the bandwidth as in the case of the FDM system. It becomes possible.

  In the above description, the ADSL modem apparatus is described as an example. However, the present invention can be similarly applied to an xDSL modem applied to other types of DSL.

  According to the ADSL modem apparatus and the communication control method according to the present invention, it is possible to efficiently switch between a stable communication capability using a method using FDM and a communication capability excellent in downstream communication speed using a method using an echo canceller. It is useful in that it can perform data communication and can provide an ADSL service with higher usability.

The figure which shows schematic structure of the communication system by the side of the terminal device installed in the house etc. where the ADSL modem apparatus which concerns on one embodiment of this invention is applied Functional block diagram of a transceiver included in the ADSL modem apparatus according to the above embodiment Functional block diagram for explaining an echo canceller function in the ADSL modem apparatus according to the above embodiment Flow chart for explaining an operation when data communication is performed by selecting the FDM system or the EC system in the ADSL modem apparatus according to the above embodiment. The figure for demonstrating the ratio of the bandwidth used for the data communication of the up direction and the down direction in the ADSL modem apparatus which concerns on the said embodiment. The figure for demonstrating the ratio of the bandwidth used for the data communication of the up direction and the down direction in the ADSL modem apparatus which concerns on the said embodiment. The flowchart for demonstrating the operation | movement when the ADSL modem apparatus which concerns on the said embodiment determines the ratio of the bandwidth used for the uplink data communication, and the bandwidth used for the downlink data communication (A) G. The figure which shows the carrier index used upstream and downstream in dmt (b) The figure which shows the state which overlap | superposed the carrier index used upstream with the low frequency side of downstream

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Splitter 2 ADSL modem apparatus 3 User terminal 4 Telephone 11 Transceiver 12 Host 13 AFE
DESCRIPTION OF SYMBOLS 14 Analog filter 15 Driver 16 Hybrid 17 Receiver 18 Analog filter 20 Processor 21 Reed-Solomon encoding part 22 Interleaving part 23 Trellis encoding part 24 Tone ordering part 25 Constellation encoding part 26 IFFT part 27 FFT part 28 Constellation decoding / FEQ unit 29 Tone deordering unit 30 Viterbi decoding unit 31 Deinterleaving unit 32 Reed-Solomon decoding unit 33 RAM
41 Echo canceller 42 Subtractor

Claims (14)

  A calculation means for calculating an S / N ratio when using an echo canceller and an S / N ratio with respect to a received signal from a partner ADSL modem apparatus connected via a line, and when using frequency division multiplexing; Selection means for selecting use of an echo canceller or frequency division multiplexing in subsequent data communication based on the S / N ratio, and notification means for notifying the partner ADSL modem apparatus of the selection result of the selection means A communication means for performing data communication with the counterpart ADSL modem apparatus using any one of the methods.   The selection means selects the use of frequency division multiplexing when the communication speed when using frequency division multiplexing exceeds the communication speed when using an echo canceller at the downlink communication speed in the ADSL service. The ADSL modem apparatus according to claim 1.   The selection means selects the use of the echo canceller when the communication speed when the echo canceller is used exceeds the communication speed when the frequency division multiplexing is used at the downlink communication speed in the ADSL service. The ADSL modem apparatus according to claim 1.   The selection means selects the use of frequency division multiplexing when the communication speed when using an echo canceller is lower than a predetermined value at an upstream communication speed in an ADSL service. 3. The ADSL modem apparatus according to 3.   The ADSL service further comprises changing means for changing a ratio of a bandwidth used for uplink data communication and a bandwidth used for downlink data communication, and the notification means sets the changed bandwidth ratio. 2. The ADSL modem according to claim 1, wherein the other ADSL modem apparatus is notified, and the communication means performs data communication with the other party ADSL modem apparatus based on the bandwidth ratio after the change. apparatus.   The changing means increases a bandwidth ratio used for uplink data communication according to a capacity of data to be transmitted, while reducing a bandwidth ratio used for downlink data communication. The ADSL modem apparatus according to claim 5.   The ADSL modem apparatus according to claim 6, wherein the changing unit determines a capacity of the data to be transmitted according to a type of data to be transmitted.   The S / N ratio for the received signal from the partner ADSL modem apparatus connected via the line, when the echo canceller is used and when the frequency division multiplexing is used, is calculated. The use of echo canceller or frequency division multiplexing in subsequent data communication is selected based on the N ratio, the selection result is notified to the partner ADSL modem apparatus, and the partner ADSL modem is notified using any of the notified methods. A communication control method comprising performing data communication with an apparatus.   9. The use of frequency division multiplexing is selected when the communication speed when using frequency division multiplexing exceeds the communication speed when using an echo canceller at the downlink communication speed in the ADSL service. The communication control method described.   9. The use of an echo canceller is selected when a communication speed when using an echo canceller exceeds a communication speed when using frequency division multiplexing at a downlink communication speed in an ADSL service. Communication control method.   11. The communication control according to claim 10, wherein, in the uplink communication speed in the ADSL service, when the communication speed when the echo canceller is used falls below a predetermined specified value, the use of frequency division multiplexing is selected. Method.   Change the ratio of the bandwidth used for uplink data communication and the bandwidth used for downlink data communication in the ADSL service, notify the partner ADSL modem apparatus of the changed bandwidth ratio, and after the change 9. The communication control method according to claim 8, wherein data communication is performed with the partner ADSL modem apparatus according to a bandwidth ratio of the other party.   13. The ratio of bandwidth used for uplink data communication is increased according to the capacity of data to be transmitted, while the ratio of bandwidth used for downlink data communication is decreased. The communication control method described.   The communication control method according to claim 13, wherein a capacity of the data to be transmitted is determined according to a type of data to be transmitted.

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