WO2006092861A1 - Line terminating apparatus and transmission control method - Google Patents

Line terminating apparatus and transmission control method Download PDF

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Publication number
WO2006092861A1
WO2006092861A1 PCT/JP2005/003598 JP2005003598W WO2006092861A1 WO 2006092861 A1 WO2006092861 A1 WO 2006092861A1 JP 2005003598 W JP2005003598 W JP 2005003598W WO 2006092861 A1 WO2006092861 A1 WO 2006092861A1
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WO
WIPO (PCT)
Prior art keywords
transmission quality
transmission
line
deteriorated
average value
Prior art date
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PCT/JP2005/003598
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French (fr)
Japanese (ja)
Inventor
Kazutomo Hasegawa
Yuri Yamazaki
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Fujitsu Access Limited
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Priority to PCT/JP2005/003598 priority Critical patent/WO2006092861A1/en
Publication of WO2006092861A1 publication Critical patent/WO2006092861A1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0015—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the adaptation strategy
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0002—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate
    • H04L1/0003—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate by switching between different modulation schemes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0023—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the signalling
    • H04L1/0026—Transmission of channel quality indication
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0264—Arrangements for coupling to transmission lines
    • H04L25/0298—Arrangement for terminating transmission lines
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2602—Signal structure

Definitions

  • the present invention relates to a line terminating device that intermittently receives interference and terminates a communication path used for multicarrier transmission or multilevel transmission, and a transmission control method that realizes the line terminating device.
  • ADSL and VDSL which are capable of providing transmission services using a pro-band at a low cost, have been widely used by utilizing the surplus transmission band of analog subscriber lines.
  • TCM Time Compression Multiplex
  • the transmission quality (S / N ratio) of the above-mentioned digital subscriber line such as ADSL is indicated by a thick dotted line (1) and a thin dotted line (2) in FIG. 4 and as shown in FIG.
  • it is often degraded by near-end crosstalk and far-end crosstalk by ISDN lines accommodated in the same cable as the digital subscriber line.
  • the central office 30 of the telephone station includes an intra-station line termination unit (OSU) 31 connected to one end of the ISDN line, and an ADSL terminal host HATU-C) 32 connected to one end of the ADSL line. Is provided. Furthermore, in the subscriber's home 40 of these ISDN lines and ADSL lines, a digital line termination device (DSU) 41 connected to the other end of the ISDN line and an ADSL terminal connected to the other end of the ADSL line. Unit (ATU-R) 42 is provided.
  • OSU intra-station line termination unit
  • ADSL terminal host HATU-C ADSL terminal host
  • ATU-R ADSL terminal host
  • the deterioration in transmission quality described above is related to the following “dual bit pine” for ADSL lines, for example, as ITU-T recommendations G. 992.1 and G. 992.2 as Annex C. This has been mitigated by the use of the “system” (hereinafter referred to as “first conventional example”).
  • the digital line terminator is used for ISDN lines.
  • the transmission quality is greatly degraded as shown in Fig. 5 due to the near-end crosstalk, which has a higher level than the far-end crosstalk described above. Therefore, the corresponding ADSL line is connected to the multi-carrier system (DMT (Discrete As shown in Fig.
  • the number of bits (word length) of transmission information per subchannel realized based on the Multi-Tone method is set.
  • the cause of the decrease in transmission quality is “compared to the above-mentioned near-end crosstalk”. Since the level is “Small! / Far-end crosstalk”, the “number of bits of transmission information per subchannel (word length)” is set large as shown in FIG.
  • Patent Document 1 Japanese Patent Laid-Open No. 2001-298499
  • Patent Document 2 US Patent 6.580.752
  • the "number of bits of transmission information per subchannel” (hereinafter, referred to as “the number of bits of transmission information per subchannel”), based on the average value of the degradation of the transmission quality, regardless of the transmission quality. Simply called “symbol length”). Therefore, for example, in the “high noise section”, there is not enough room to allow deterioration in transmission quality due to interference or disturbance other than near-end crosstalk, and the desired transmission quality is not always stable. It was difficult to secure.
  • An object of the present invention is to propose a line termination device and a transmission control method in which transmission quality is stably kept high and the transmission rate is maintained and improved.
  • the transmission quality monitoring means includes a signal received via the line.
  • the average value of the transmission quality and the deteriorated transmission quality in which the transmission quality is deteriorated according to the interference are obtained.
  • the control means uses the deteriorated transmission quality as a reference to transmit symbols through individual carriers that realize the multicarrier transmission. If the difference is smaller than the predetermined threshold, the symbol size is set based on the average value.
  • the transmission quality monitoring means obtains an average value of transmission quality and a deteriorated transmission quality for a known signal used for evaluation of transmission characteristics of the line.
  • the predetermined threshold value is a half value of the transmission quality increment in which the symbol size is allowed to increase by the predetermined unit.
  • the transmission quality monitoring means transmits the signal received through the line.
  • An average value of transmission quality and a deteriorated transmission quality in which the transmission quality is deteriorated according to the interference are obtained.
  • the control means sets the number or size of symbols for realizing the multilevel transmission based on the deteriorated transmission quality, and sets the difference Is less than the predetermined threshold value, the number or size of the symbols is set based on the average value.
  • the transmission quality monitoring means obtains an average value of transmission quality and a deteriorated transmission quality for a known signal used for evaluation of transmission characteristics of the line.
  • both the average value of transmission quality and the deteriorated transmission quality can be obtained accurately with a small amount of processing compared to the case where the signal is obtained for an unknown signal.
  • the predetermined threshold value is a value half the transmission quality increment in which the number of symbols or the word length is allowed to increase by a predetermined unit.
  • interference is received intermittently and An average value of transmission quality of a signal received via a line used for carrier transmission and a degraded transmission quality in which the transmission quality is deteriorated according to the interference are required. Subsequently, when a difference between the average value and the deteriorated transmission quality exceeds a predetermined threshold, a symbol transmitted via each carrier realizing the multi-carrier transmission is used with the deteriorated transmission quality as a reference. When a size is set and the difference is less than the predetermined threshold, the size of the symbol is set based on the average value.
  • the calculation procedure is simplified and the processing amount is reduced.
  • the symbol size described above is set to be constant regardless of the period, the transmission speed is unnecessarily reduced and the margin for transmission quality is reduced. Is done.
  • the average value of the transmission quality of a signal that is intermittently interfered and received via a line used for multilevel transmission, and the transmission quality are the interference quality. Therefore, deteriorated transmission quality deteriorated according to the demand. Subsequently, when the difference between the average value and the deteriorated transmission quality exceeds a predetermined threshold, the number or size of symbols for realizing the multi-value transmission is set based on the deteriorated transmission quality. Is less than the predetermined threshold, the number or size of the symbols is set based on the average value.
  • the calculation procedure is simplified and the processing amount is reduced.
  • the symbol size described above is set to be constant regardless of the period, the transmission speed is unnecessarily reduced and the margin for transmission quality is reduced. Is done.
  • the transmission rate is stably maintained high in accordance with the transmission quality.
  • the transmission quality margin is stably ensured in both the period in which the interference is received and the period in which the interference is not received.
  • FIG. 1 is a diagram showing first and second embodiments of the present invention.
  • FIG. 2 is an operation flowchart of the first embodiment of the present invention.
  • FIG. 3 is a diagram for explaining the operation of the second embodiment of the present invention.
  • FIG. 4 A diagram showing an example of the configuration of in-station equipment and in-house equipment related to DSL and ISDN lines laid via a common cable.
  • FIG. 5 is a diagram showing transmission quality degradation according to near-end crosstalk and far-end crosstalk.
  • FIG. 6 is a diagram showing the number of bits per subchannel set based on the dual bitmap scheme.
  • FIG. 7 is a diagram showing the number of bits per subchannel set for a VDSL line.
  • FIG. 8 is a diagram showing the number of bits per subchannel set by the invention related to the present invention.
  • FIG. 1 is a diagram showing first and second embodiments of the present invention.
  • the home 40 is provided with an ADSL terminal unit (AT U-R) 10 configured as follows.
  • ADSL terminal unit ADSL terminal unit
  • the ADSL terminal unit 10 includes a receiver 1 OR and a transmitter 10T connected to the “downlink” and “uplink” of the ADSL line described above.
  • the above-described “downlink” is connected to the input of demodulator 11, and one output of demodulator 11 is connected to the subtracted input of subtractor 12.
  • a reference signal is input to the subtracted input of the subtractor 12, and the output of the subtractor 12 is connected to one input of the selector 13 and one input of the SN ratio measuring unit 14.
  • the above-described reference signal is input to the other input of the SN ratio measurement unit 14, and the output of the SN ratio measurement unit 14 is connected to one input of the difference determination unit 15.
  • the other output of the demodulator 11 is connected to the input of the frequency divider 16, and a predetermined clock signal is input to the clock input of the frequency divider 16.
  • the output of the frequency divider 16 is connected to the other input of the selector 13 via the phase determination unit 17, and the output of the selector 13 is connected to one input of the SN ratio measurement unit 18.
  • the above-mentioned reference signal is input to the other input of the SN ratio measurement unit 18, and the output of the SN ratio measurement unit 18 determines the difference.
  • the output of the difference determination unit 15 is connected to the control input of the transmission unit 10T via the bit number conversion unit 19.
  • FIG. 2 is an operation flowchart of the first embodiment of the present invention.
  • the demodulator 11 demodulates the DMT symbol received via the ADSL line and input as received data on which the above-described far-end crosstalk or near-end crosstalk is superimposed.
  • the subtractor 12 compares the demodulated signal generated as a result of such demodulation with a reference signal indicating a known DMT symbol, thereby generating an error signal indicating the difference between the two.
  • the frequency divider 16 divides the clock signal described above to generate a timing signal that is phase-synchronized with the received data and that indicates the interval between DMT symbols. Further, the phase determination unit 17 divides the timing signal to generate a timing signal indicating a hyperframe interval.
  • the selector 13 identifies the “high noise period” in which the above-described near-end crosstalk occurs (the digital line terminating device 41 transmits to the ISDN line) based on such a timing signal, and An error signal is given to the SN ratio measurement unit 18.
  • the SN ratio measurement unit 18 converts the error signal into an SN ratio (hereinafter referred to as “high noise interval SN ratio”).
  • the S / N ratio measurement unit 14 steadily calculates the S / N ratio (hereinafter referred to as “average S / N ratio”) of the error signal described above, regardless of the power of the “high noise interval”. Ask.
  • the difference determination unit 15 obtains a difference ⁇ (> 0) between these “average SN ratio” and “high noise interval SN ratio” (step Sl in FIG. 2). Further, if the difference ⁇ exceeds a predetermined threshold TH (> 0), the difference determination unit 15 may, for example, say that “desired transmission quality (SN ratio) is ensured with a predetermined margin and the force is also transmitted. “Symbol length” is set to a value that satisfies the condition that “the speed does not decrease unnecessarily” (hereinafter referred to as “word length setting condition”) with respect to the “high noise section SN ratio” (step in FIG. 2) S2).
  • the difference determination unit 15 sets the “symbol length” to a value that satisfies the above-mentioned “word length setting condition” under the “average SN ratio”. ( Figure 2 Step S3).
  • the bit number conversion unit 19 notifies the “symbol length” to the ATU-C32 via the transmission unit 10T. That is, the “symbol length” is set based on the “high noise interval SN ratio” during the period when the “high noise interval SN ratio” is lower than the “average SN ratio” by a threshold TH or more. This period is set based on the “average signal-to-noise ratio”.
  • the level of interference periodically received by the ISDN line is not as great as the level of interference similarly received by the ADSL line, and the “high noise interval SN ratio” and “ The difference from the “average signal-to-noise ratio” can be expected to be 1.5 dB or less. Therefore, stability is ensured and overall performance is improved, and the transmission speed is likely to increase by more than a dozen megabits per second.
  • FIG. 3 is a diagram for explaining the operation of the second embodiment of the present invention.
  • the threshold TH is selected as follows.
  • the “symbol length” is a desired value K (> 0), (The minimum signal-to-noise ratio to be set for each of K-1) is determined in advance.
  • the present invention is applied when the “symbol length” is any one of two desired values ⁇ and ( ⁇ 1).
  • the present invention may be applied to all or part of the range in which the “symbol length” can be set, for example, in addition to such a case.
  • the N ratio may be a different value determined depending on the value K which is not constant regardless of the desired value K.
  • a modulation scheme in which the symbol length is changed in units of a plurality of bits may be applied to individual subchannels in addition to such a modulation scheme.
  • both the “high noise interval SN ratio” and the “low noise interval SN ratio” are measured only for the training signal.
  • the present invention is not limited to such a configuration, and any signal can be measured as long as these S / N ratios can be obtained with a desired accuracy and real-time property.
  • the cause of the difference in the SN ratio between the “high noise section” and the “low noise section” is that the “ping-pong transmission method is applied and the DSL line is used via a common cable.
  • such factors are, for example, interference and interference caused by interference coming from the outside as electromagnetic waves and bridge taps that realize flexible accommodation of core wires in multiple areas, not just disturbances. Moyo.
  • an ADSL line that receives interference such as crosstalk is installed in the home 40.
  • the present invention is applied to an ADSL terminal unit (ATU-R) 10 that terminates in this manner.
  • ATU-R ADSL terminal unit
  • the present invention is also applicable to the ADSL terminal unit 32 installed in the station 30.
  • the “high noise section” and the “low noise section” are identified in cooperation with the in-station device.
  • the present invention can also be applied to a device that autonomously identifies these sections by leadingly monitoring the state of the ISDN line, such as the ADSL terminal unit 32 provided in the station 30. Applicable.
  • word length setting condition itself is not a feature of the present invention.
  • the present invention is applied to a line terminating device that terminates an ADSL line to which the above-described DMT method is applied.
  • the line used for multi-level transmission is terminated instead of multi-carrier transmission or together with multi-carrier transmission.
  • the present invention can also be applied to a line termination device.
  • symbol length is set to a value satisfying “word length setting condition” for “high noise interval SN ratio” or “average SN ratio”.
  • the S / N ratio satisfying such a "word length setting condition” is, for example, "bit error rate (including that detected in the process of channel decoding)", “symbol unit” It can be replaced with a wide variety of transmission qualities, such as “Error of signal point in” and “Eye aperture observed as eye pattern”.
  • bit error rate including that detected in the process of channel decoding
  • symbol unit It can be replaced with a wide variety of transmission qualities, such as “Error of signal point in” and “Eye aperture observed as eye pattern”.
  • various embodiments are possible within the scope of the present invention, not limited to the above-described embodiments, and any improvements may be made to all or part of the constituent devices.
  • the communication system and transmission system to which the present invention is applied can flexibly adapt to the degree and form of interference that can be assumed in advance, improve service quality and reliability, and maintain stability.

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  • Engineering & Computer Science (AREA)
  • Quality & Reliability (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)

Abstract

A line terminating apparatus for terminating a communication path used for a multicarrier transmission or used for a multi-level transmission. A transmission control method for realizing that line terminating apparatus. It is an object of the invention to maintain a stable, high transmission quality and improve the transmission rate. A line terminating apparatus for terminating a line, which is intermittently subjected to interference and used for a multicarrier transmission, comprises a transmission quality monitoring means that determines an average value of the transmission quality of signals received via the line and also determines a degraded transmission quality into which the transmission quality has been degraded in accordance with the interference; and a control means that, when the difference between the average value and the degraded transmission quality exceeds a predetermined threshold value, sets a size of symbols, which are to be transmitted via carriers that realize the multicarrier transmission, with the degraded transmission quality referred to, and that, when the difference is below the predetermined threshold value, sets a size of the symbols with the average value referred to.

Description

明 細 書  Specification
回線終端装置および伝送制御方法  Line termination device and transmission control method
技術分野  Technical field
[0001] 本発明は、間欠的に干渉を受け、かつマルチキャリア伝送または多値伝送に用い られる通信路を終端する回線終端装置と、その回線終端装置を実現する伝送制御 方法とに関する。  TECHNICAL FIELD [0001] The present invention relates to a line terminating device that intermittently receives interference and terminates a communication path used for multicarrier transmission or multilevel transmission, and a transmission control method that realizes the line terminating device.
背景技術  Background art
[0002] 近年、アナログの加入者線の余剰の伝送帯域が活用されることにより、安価にプロ ードバンドによる伝送サービスが可能な ADSLや VDSLが広く普及している。  [0002] In recent years, ADSL and VDSL, which are capable of providing transmission services using a pro-band at a low cost, have been widely used by utilizing the surplus transmission band of analog subscriber lines.
し力し、このような加入者線の一部は、図 4に破線で示すように、 ISDN(Integrated Services Digital Network)回線と共通のケーブルに収容され、し力も、このような ISD N回線の伝送方向は、ピンポン伝送方式 (Time Compression Multiplex： TCM)に基 づ ヽて数ミリ秒の周期で切り替えられる。  However, some of these subscriber lines are accommodated in the same cable as the ISDN (Integrated Services Digital Network) line as shown by the broken lines in FIG. The transmission direction is switched at a cycle of several milliseconds based on the ping-pong transmission method (Time Compression Multiplex: TCM).
[0003] したがって、上述した ADSLのようなディジタル加入者線の伝送品質（SN比）は、 図 4に太い点線 (1)と細い点線 (2)とで示され、かつ図 5に示されるように、そのディジ タル加入者線と共通のケーブルに収容された ISDN回線による近端漏話および遠端 漏話によって低下する場合が多 、。  [0003] Therefore, the transmission quality (S / N ratio) of the above-mentioned digital subscriber line such as ADSL is indicated by a thick dotted line (1) and a thin dotted line (2) in FIG. 4 and as shown in FIG. In addition, it is often degraded by near-end crosstalk and far-end crosstalk by ISDN lines accommodated in the same cable as the digital subscriber line.
なお、図 4において、電話局の局内 30には、 ISDN回線の一端に接続された局内 回線終端装置 (OSU) 31と、 ADSL回線の一端に接続された ADSLターミナルュ- ッ HATU— C) 32とが備えられる。さらに、これらの ISDN回線および ADSL回線の 加入者の宅内 40には、その ISDN回線の他端に接続されたディジタル回線終端装 置（DSU) 41と、 ADSL回線の他端に接続された ADSLターミナルユニット (ATU— R) 42とが備えられる。  In FIG. 4, the central office 30 of the telephone station includes an intra-station line termination unit (OSU) 31 connected to one end of the ISDN line, and an ADSL terminal host HATU-C) 32 connected to one end of the ADSL line. Is provided. Furthermore, in the subscriber's home 40 of these ISDN lines and ADSL lines, a digital line termination device (DSU) 41 connected to the other end of the ISDN line and an ADSL terminal connected to the other end of the ADSL line. Unit (ATU-R) 42 is provided.
[0004] 従来、上述した伝送品質の低下は、 ADSL回線に関しては、例えば、 ITU— Tの勧 告 G. 992. 1、G. 992. 2に Annex Cとして規定される下記の「デュアルビットマツ プ方式」（以下、「第一の従来例」という。）が用いられることによって、軽減されていた 。「デュアルビットマップ方式」では、 ISDN回線に対してディジタル回線終端装置 41 が送信する期間には、既述の遠端漏話に比べてレベルが大きい近端漏話によって 伝送品質が図 5に示すように大幅に低下するため、該当する ADSL回線をマルチキ ャリア方式（DMT(Discrete Multi- Tone)方式）に基づいて実現するサブチャネル当 たりの伝送情報のビット数 (語長）は、図 6に示すように少なく設定される。しかし、反 対に、 ISDN回線を介して局内回線終端装置 31から引き渡される信号をディジタル 回線終端装置 41が受信する期間には、伝送品質の低下の要因が「既述の近端漏話 に比べてレベルが小さ!/、遠端漏話」であるため、「サブチャネル当たりの伝送情報の ビット数 (語長）」は、図 6に示すように多く設定される。 [0004] Conventionally, the deterioration in transmission quality described above is related to the following “dual bit pine” for ADSL lines, for example, as ITU-T recommendations G. 992.1 and G. 992.2 as Annex C. This has been mitigated by the use of the “system” (hereinafter referred to as “first conventional example”). In the “Dual Bitmap Method”, the digital line terminator is used for ISDN lines. During the transmission period, the transmission quality is greatly degraded as shown in Fig. 5 due to the near-end crosstalk, which has a higher level than the far-end crosstalk described above. Therefore, the corresponding ADSL line is connected to the multi-carrier system (DMT (Discrete As shown in Fig. 6, the number of bits (word length) of transmission information per subchannel realized based on the Multi-Tone method) is set. On the other hand, during the period when the digital line terminator 41 receives the signal delivered from the intra-station line terminator 31 via the ISDN line, the cause of the decrease in transmission quality is “compared to the above-mentioned near-end crosstalk”. Since the level is “Small! / Far-end crosstalk”, the “number of bits of transmission information per subchannel (word length)” is set large as shown in FIG.
[0005] なお、以下では、既述の近端漏話と遠端漏話とがそれぞれ生じる期間をそれぞれ「 高雑音区間」および「低雑音区間」と称する。  [0005] In the following, the periods in which near-end crosstalk and far-end crosstalk described above occur are referred to as "high noise section" and "low noise section", respectively.
また、 VDSL回線に関しては、上記の Annex Cに該当する規定は、 ITU— Tの勧 告に無い。したがって、既述の「高雑音区間」および「低雑音区間」には、「サブチヤ ネル当たりの伝送情報のビット数」が「近端漏話と遠端漏話に応じた伝送品質の平均 的な劣化分が軽減される一定の値（図 7に太い実線で示される。；)」に設定されること によって、その伝送品質の低下の軽減が図られている。以下、このような従来例につ いては、「第二の従来例」という。  Regarding VDSL lines, there is no ITU-T recommendation for provisions that fall under Annex C above. Therefore, in the above-mentioned “high noise interval” and “low noise interval”, the “number of bits of transmission information per subchannel” is “average transmission quality degradation according to near-end crosstalk and far-end crosstalk”. Is set to a certain value that is reduced (indicated by a thick solid line in Fig. 7)), the reduction in transmission quality is reduced. Hereinafter, such a conventional example is referred to as a “second conventional example”.
[0006] なお、本発明に関連した先行技術としては、下記の特許文献 1、 2に開示されるよう に、既述の「高雑音区間」と「低雑音区間」とにおける伝送品質 (SN比）が予め計測さ れ、かつ図 8に示すように、これらの伝送品質（SN比）の如何にかかわらず所望の伝 送品質が確保される一定の小さな値に「サブチャネル当たりの伝送情報のビット数」 が設定されることによって、平均的な伝送速度が低下するが、上記の「デュアルビット マップ方式」が適用された場合より伝送品質が高く維持される技術がある。  [0006] As prior art related to the present invention, as disclosed in the following Patent Documents 1 and 2, the transmission quality (SN ratio) in the above-mentioned "high noise interval" and "low noise interval" is disclosed. ) Is measured in advance, and as shown in FIG. 8, the transmission information per subchannel is set to a certain small value that ensures the desired transmission quality regardless of the transmission quality (SN ratio). Although the average transmission rate is reduced by setting the “number of bits”, there is a technique in which the transmission quality is maintained higher than when the above “dual bit map method” is applied.
特許文献 1：特開 2001— 298499号公報  Patent Document 1: Japanese Patent Laid-Open No. 2001-298499
特許文献 2 :米国特許 6. 580. 752号  Patent Document 2: US Patent 6.580.752
発明の開示  Disclosure of the invention
発明が解決しょうとする課題  Problems to be solved by the invention
[0007] ところで、上述した第一の従来例では、伝送品質の低下は、既述の近端漏話と遠 端漏話とのそれぞれに応じた伝送品質を設定することで軽減される。しかし、このよう な伝送品質の低下は既述の第二の従来例に比べて大幅に複雑な処理によって実現 され、しかも、「その処理の過程で更新され、かつ参照される情報の情報量」が多いた めに、メモリ等の多くの資源が必要であった。 [0007] By the way, in the first conventional example described above, the reduction in transmission quality is mitigated by setting the transmission quality corresponding to each of the above-mentioned near-end crosstalk and far-end crosstalk. But like this A significant decrease in transmission quality is achieved by a significantly more complex process than the second conventional example described above, and because there is a large amount of information that is updated and referenced during the process. In addition, many resources such as a memory are required.
[0008] また、上述した第二の従来例では、伝送品質の如何にかかわらず、その伝送品質 の劣化分の平均値に基づ 、て「サブチャネル当たりの伝送情報のビット数」（以下、 単に「シンボル長」という。）が決定される。したがって、例えば、「高雑音区間」には、 近端漏話以外の干渉や外乱による伝送品質の劣化が許容されるための余裕度が十 分には確保されず、かつ所望の伝送品質が必ずしも安定には確保され難力つた。  [0008] Also, in the second conventional example described above, the "number of bits of transmission information per subchannel" (hereinafter, referred to as "the number of bits of transmission information per subchannel"), based on the average value of the degradation of the transmission quality, regardless of the transmission quality. Simply called "symbol length"). Therefore, for example, in the “high noise section”, there is not enough room to allow deterioration in transmission quality due to interference or disturbance other than near-end crosstalk, and the desired transmission quality is not always stable. It was difficult to secure.
[0009] 本発明は、伝送品質が安定に高く維持され、しかも、伝送速度の維持および向上 が図られる回線終端装置および伝送制御方法を提案することを目的とする。  [0009] An object of the present invention is to propose a line termination device and a transmission control method in which transmission quality is stably kept high and the transmission rate is maintained and improved.
課題を解決するための手段  Means for solving the problem
[0010] 本発明にかかわる回線終端装置では、間欠的に干渉を受け、かつマルチキャリア 伝送に用いられる回線を終端する回線終端装置において、伝送品質監視手段は、 前記回線を介して受信される信号の伝送品質の平均値と、前記伝送品質が前記干 渉に応じて劣化した劣化伝送品質とを求める。制御手段は、前記平均値と前記劣化 伝送品質との差が既定の閾値を上回る場合には、前記劣化伝送品質を基準として、 前記マルチキャリア伝送を実現する個々のキャリアを介して伝送されるシンボルのサ ィズを設定し、かつ前記差が前記既定の閾値を下回る場合には、前記平均値を基準 として前記シンボルのサイズを設定する。 [0010] In the line termination apparatus according to the present invention, in the line termination apparatus that receives interference intermittently and terminates the line used for multicarrier transmission, the transmission quality monitoring means includes a signal received via the line. The average value of the transmission quality and the deteriorated transmission quality in which the transmission quality is deteriorated according to the interference are obtained. When the difference between the average value and the deteriorated transmission quality exceeds a predetermined threshold, the control means uses the deteriorated transmission quality as a reference to transmit symbols through individual carriers that realize the multicarrier transmission. If the difference is smaller than the predetermined threshold, the symbol size is set based on the average value.
[0011] すなわち、既述の干渉を受ける期間と、その干渉を受けない期間との双方における 伝送品質が求められなければならない従来例に比べて、演算手順の簡略化および 処理量の削減が図られ、かつこれらの期間の如何にかかわらず上述したシンボルの サイズが一定に設定される他の従来例に比べて、伝送速度の無用な低下と、伝送品 質にかかわる余裕度の不足とが軽減される。  [0011] That is, the calculation procedure is simplified and the amount of processing is reduced compared to the conventional example in which the transmission quality in both the period in which the interference is received and the period in which the interference is not required must be obtained. Compared to other conventional examples in which the symbol size described above is set to be constant regardless of the period, the transmission speed is unnecessarily reduced and the margin for transmission quality is reduced. Is done.
[0012] また、本発明にかかわる回線終端装置では、伝送品質監視手段は、回線の伝送特 性の評価に用いられる既知の信号について、伝送品質の平均値と劣化伝送品質と を求める。  [0012] Further, in the line terminating apparatus according to the present invention, the transmission quality monitoring means obtains an average value of transmission quality and a deteriorated transmission quality for a known signal used for evaluation of transmission characteristics of the line.
すなわち、伝送品質の平均値と劣化伝送品質とは、何れも、既知ではない信号に ついて求められる場合に比べて、少ない処理量で精度よく求められる。 さらに、本発明にかかわる回線終端装置では、既定の閾値は、シンボルのサイズが 既定の単位増加することが許容される伝送品質の増分の半分の値である。 In other words, both the average value of transmission quality and the degraded transmission quality are not known signals. Therefore, it can be obtained with a small amount of processing and with high accuracy as compared with the case where it is required. Further, in the line termination apparatus according to the present invention, the predetermined threshold value is a half value of the transmission quality increment in which the symbol size is allowed to increase by the predetermined unit.
[0013] すなわち、既述の干渉を受ける期間においても安定した伝送品質の余裕度が確保 される。  [0013] That is, a stable margin of transmission quality is ensured even during the above-described period of interference.
また、本発明にかかわる回線終端装置では、間欠的に干渉を受け、かつ多値伝送 に用いられる回線を終端する回線終端装置において、伝送品質監視手段は、前記 回線を介して受信される信号の伝送品質の平均値と、前記伝送品質が前記干渉に 応じて劣化した劣化伝送品質とを求める。制御手段は、前記平均値と前記劣化伝送 品質との差が既定の閾値を上回る場合には、前記劣化伝送品質を基準として前記 多値伝送を実現するシンボルの数またはサイズを設定し、前記差が前記既定の閾値 を下回る場合には、前記平均値を基準として前記シンボルの数またはサイズを設定 する。  In the line termination apparatus according to the present invention, in the line termination apparatus that receives interference intermittently and terminates the line used for multilevel transmission, the transmission quality monitoring means transmits the signal received through the line. An average value of transmission quality and a deteriorated transmission quality in which the transmission quality is deteriorated according to the interference are obtained. When the difference between the average value and the deteriorated transmission quality exceeds a predetermined threshold, the control means sets the number or size of symbols for realizing the multilevel transmission based on the deteriorated transmission quality, and sets the difference Is less than the predetermined threshold value, the number or size of the symbols is set based on the average value.
[0014] すなわち、既述の干渉を受ける期間と、その干渉を受けない期間との双方における 伝送品質が求められなければならない従来例に比べて、演算手順の簡略化および 処理量の削減が図られ、かつこれらの期間の如何にかかわらず上述したシンボルの サイズが一定に設定される他の従来例に比べて、伝送速度の無用な低下と、伝送品 質にかかわる余裕度の不足とが軽減される。  [0014] That is, compared with the conventional example in which transmission quality in both the period in which the interference is received and the period in which the interference is not received must be obtained, the calculation procedure is simplified and the processing amount is reduced. Compared to other conventional examples in which the symbol size described above is set to be constant regardless of the period, the transmission speed is unnecessarily reduced and the margin for transmission quality is reduced. Is done.
[0015] さらに、本発明にかかわる回線終端装置では、伝送品質監視手段は、回線の伝送 特性の評価に用いられる既知の信号について、伝送品質の平均値と、劣化伝送品 質とを求める。 [0015] Further, in the line termination apparatus according to the present invention, the transmission quality monitoring means obtains an average value of transmission quality and a deteriorated transmission quality for a known signal used for evaluation of transmission characteristics of the line.
すなわち、伝送品質の平均値と劣化伝送品質とは、何れも、既知ではない信号に ついて求められる場合に比べて、少ない処理量で精度よく求められる。  In other words, both the average value of transmission quality and the deteriorated transmission quality can be obtained accurately with a small amount of processing compared to the case where the signal is obtained for an unknown signal.
また、本発明にかかわる回線終端装置では、既定の閾値は、シンボルの数または 語長が既定の単位増加することが許容される伝送品質の増分の半分の値である。  In the line termination apparatus according to the present invention, the predetermined threshold value is a value half the transmission quality increment in which the number of symbols or the word length is allowed to increase by a predetermined unit.
[0016] すなわち、既述の干渉を受ける期間においても安定した伝送品質の余裕度が確保 される。 [0016] That is, a stable margin of transmission quality is ensured even during the period of receiving the above-described interference.
さらに、本発明にかかわる伝送制御方法では、間欠的に干渉を受け、かつマルチ キャリア伝送に用いられる回線を介して受信される信号の伝送品質の平均値と、前記 伝送品質が前記干渉に応じて劣化した劣化伝送品質とが求められる。続いて、前記 平均値と前記劣化伝送品質との差が既定の閾値を上回る場合には、前記劣化伝送 品質を基準として、前記マルチキャリア伝送を実現する個々のキャリアを介して伝送 されるシンボルのサイズが設定され、かつ前記差が前記既定の閾値を下回る場合に は、前記平均値を基準として前記シンボルのサイズが設定される。 Furthermore, in the transmission control method according to the present invention, interference is received intermittently and An average value of transmission quality of a signal received via a line used for carrier transmission and a degraded transmission quality in which the transmission quality is deteriorated according to the interference are required. Subsequently, when a difference between the average value and the deteriorated transmission quality exceeds a predetermined threshold, a symbol transmitted via each carrier realizing the multi-carrier transmission is used with the deteriorated transmission quality as a reference. When a size is set and the difference is less than the predetermined threshold, the size of the symbol is set based on the average value.
[0017] すなわち、既述の干渉を受ける期間と、その干渉を受けない期間との双方における 伝送品質が求められなければならない従来例に比べて、演算手順の簡略化および 処理量の削減が図られ、かつこれらの期間の如何にかかわらず上述したシンボルの サイズが一定に設定される他の従来例に比べて、伝送速度の無用な低下と、伝送品 質にかかわる余裕度の不足とが軽減される。  That is, compared to the conventional example in which transmission quality in both the period in which the interference is received and the period in which the interference is not required is required, the calculation procedure is simplified and the processing amount is reduced. Compared to other conventional examples in which the symbol size described above is set to be constant regardless of the period, the transmission speed is unnecessarily reduced and the margin for transmission quality is reduced. Is done.
[0018] また、本発明にかかわる伝送制御方法では、間欠的に干渉を受け、かつ多値伝送 に用いられる回線を介して受信される信号の伝送品質の平均値と、前記伝送品質が 前記干渉に応じて劣化した劣化伝送品質とが求められる。続いて、前記平均値と前 記劣化伝送品質との差が既定の閾値を上回る場合には、前記劣化伝送品質を基準 として前記多値伝送を実現するシンボルの数またはサイズが設定され、前記差が前 記既定の閾値を下回る場合には、前記平均値を基準として前記シンボルの数または サイズが設定される。 [0018] Further, in the transmission control method according to the present invention, the average value of the transmission quality of a signal that is intermittently interfered and received via a line used for multilevel transmission, and the transmission quality are the interference quality. Therefore, deteriorated transmission quality deteriorated according to the demand. Subsequently, when the difference between the average value and the deteriorated transmission quality exceeds a predetermined threshold, the number or size of symbols for realizing the multi-value transmission is set based on the deteriorated transmission quality. Is less than the predetermined threshold, the number or size of the symbols is set based on the average value.
[0019] すなわち、既述の干渉を受ける期間と、その干渉を受けない期間との双方における 伝送品質が求められなければならない従来例に比べて、演算手順の簡略化および 処理量の削減が図られ、かつこれらの期間の如何にかかわらず上述したシンボルの サイズが一定に設定される他の従来例に比べて、伝送速度の無用な低下と、伝送品 質にかかわる余裕度の不足とが軽減される。  That is, compared to the conventional example in which transmission quality in both the period in which the above-described interference is received and the period in which the interference is not received is required, the calculation procedure is simplified and the processing amount is reduced. Compared to other conventional examples in which the symbol size described above is set to be constant regardless of the period, the transmission speed is unnecessarily reduced and the margin for transmission quality is reduced. Is done.
発明の効果  The invention's effect
[0020] 本発明では、伝送品質に併せて伝送速度が安定に高く維持される。  [0020] In the present invention, the transmission rate is stably maintained high in accordance with the transmission quality.
また、本発明では、干渉を受ける期間と、その干渉を受けない期間との何れにおい ても、伝送品質の余裕度が安定に確保される。  Further, according to the present invention, the transmission quality margin is stably ensured in both the period in which the interference is received and the period in which the interference is not received.
図面の簡単な説明 [0021] [図 1]本発明の第一および第二の実施形態を示す図である。 Brief Description of Drawings FIG. 1 is a diagram showing first and second embodiments of the present invention.
[図 2]本発明の第一の実施形態の動作フローチャートである。  FIG. 2 is an operation flowchart of the first embodiment of the present invention.
[図 3]本発明の第二の実施形態の動作を説明する図である。  FIG. 3 is a diagram for explaining the operation of the second embodiment of the present invention.
[図 4]共通のケーブルを介して敷設された DSLと ISDN回線とにかかわる局内設備お よび宅内設備の構成例を示す図である。  [Fig. 4] A diagram showing an example of the configuration of in-station equipment and in-house equipment related to DSL and ISDN lines laid via a common cable.
[図 5]近端漏話と遠端漏話とに応じた伝送品質の劣化を示す図である。  FIG. 5 is a diagram showing transmission quality degradation according to near-end crosstalk and far-end crosstalk.
[図 6]デュアルビットマップ方式に基づいて設定されるサブチャネル当たりのビット数 を示す図である。  FIG. 6 is a diagram showing the number of bits per subchannel set based on the dual bitmap scheme.
[図 7]VDSL回線に設定されるサブチャネル当たりのビット数を示す図である。  FIG. 7 is a diagram showing the number of bits per subchannel set for a VDSL line.
[図 8]本発明に関連した発明によって設定されるサブチャネル当たりのビット数を示す 図である。  FIG. 8 is a diagram showing the number of bits per subchannel set by the invention related to the present invention.
発明を実施するための最良の形態  BEST MODE FOR CARRYING OUT THE INVENTION
[0022] 以下、図面に基づいて本発明の実施形態について詳細に説明する。  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
図 1は、本発明の第一および第二の実施形態を示す図である。  FIG. 1 is a diagram showing first and second embodiments of the present invention.
図において、宅内 40には、下記の通りに構成される ADSLターミナルユニット (AT U-R) 10が備えられる。  In the figure, the home 40 is provided with an ADSL terminal unit (AT U-R) 10 configured as follows.
ADSLターミナルユニット 10は、既述の ADSL回線の「下りのリンク」と「上りのリンク 」とにそれぞれ接続された受信部 1 ORと送信部 10Tとから構成される。  The ADSL terminal unit 10 includes a receiver 1 OR and a transmitter 10T connected to the “downlink” and “uplink” of the ADSL line described above.
[0023] 受信部 10Rでは、既述の「下りのリンク」が復調器 11の入力に接続され、その復調 器 11の一方の出力は減算器 12の減数入力に接続される。減算器 12の被減算入力 にはリファレンス信号が入力され、その減算器 12の出力はセレクタ 13の一方の入力 と SN比測定部 14の一方の入力とに接続される。 SN比測定部 14の他方の入力には 上述したリファレンス信号が入力され、その SN比測定部 14の出力は差分判定部 15 の一方の入力に接続される。復調器 11の他方の出力は分周器 16の入力に接続さ れ、その分周器 16のクロック入力には所定のクロック信号が入力される。分周器 16の 出力は位相判定部 17を介してセレクタ 13の他方の入力に接続され、そのセレクタ 13 の出力は SN比測定部 18の一方の入力に接続される。 SN比測定部 18の他方の入 力には既述のリファレンス信号が入力され、その SN比測定部 18の出力は差分判定 部 15の他方の入力に接続される。差分判定部 15の出力は、ビット数換算部 19を介 して送信部 10Tの制御入力に接続される。 In receiving section 10 R, the above-described “downlink” is connected to the input of demodulator 11, and one output of demodulator 11 is connected to the subtracted input of subtractor 12. A reference signal is input to the subtracted input of the subtractor 12, and the output of the subtractor 12 is connected to one input of the selector 13 and one input of the SN ratio measuring unit 14. The above-described reference signal is input to the other input of the SN ratio measurement unit 14, and the output of the SN ratio measurement unit 14 is connected to one input of the difference determination unit 15. The other output of the demodulator 11 is connected to the input of the frequency divider 16, and a predetermined clock signal is input to the clock input of the frequency divider 16. The output of the frequency divider 16 is connected to the other input of the selector 13 via the phase determination unit 17, and the output of the selector 13 is connected to one input of the SN ratio measurement unit 18. The above-mentioned reference signal is input to the other input of the SN ratio measurement unit 18, and the output of the SN ratio measurement unit 18 determines the difference. Connected to the other input of unit 15. The output of the difference determination unit 15 is connected to the control input of the transmission unit 10T via the bit number conversion unit 19.
[第一の実施形態]  [First embodiment]
図 2は、本発明の第一の実施形態の動作フローチャートである。  FIG. 2 is an operation flowchart of the first embodiment of the present invention.
[0024] 以下、図 1および図 2を参照して本実施形態の動作を説明する。 Hereinafter, the operation of the present embodiment will be described with reference to FIG. 1 and FIG.
復調器 11は、 ADSL回線を介して受信され、かつ既述の遠端漏話または近端漏 話が重畳された受信データとして入力される DMTシンボルを復調する。減算器 12 は、このような復調の結果として生成される復調信号と、既知の DMTシンボルを示す リファレンス信号とを比較することによって、両者の差を示す誤差信号を生成する。  The demodulator 11 demodulates the DMT symbol received via the ADSL line and input as received data on which the above-described far-end crosstalk or near-end crosstalk is superimposed. The subtractor 12 compares the demodulated signal generated as a result of such demodulation with a reference signal indicating a known DMT symbol, thereby generating an error signal indicating the difference between the two.
[0025] また、分周器 16は、既述のクロック信号を分周することによって、上述した受信デー タに位相同期し、かつ DMTシンボルの間隔を示すタイミング信号を生成する。さらに 、位相判定部 17はこのタイミング信号を分周することによって、ハイパーフレーム間 隔を示すタイミング信号を生成する。 Further, the frequency divider 16 divides the clock signal described above to generate a timing signal that is phase-synchronized with the received data and that indicates the interval between DMT symbols. Further, the phase determination unit 17 divides the timing signal to generate a timing signal indicating a hyperframe interval.
セレクタ 13は、このようなタイミング信号に基づいて既述の近端漏話が発生する（デ イジタル回線終端装置 41が ISDN回線宛に送信する）「高雑音期間」を特定し、その 期間における上記の誤差信号を SN比測定部 18に与える。 SN比測定部 18は、その 誤差信号を SN比 (以下、「高雑音区間 SN比」という。）に換算する。  The selector 13 identifies the “high noise period” in which the above-described near-end crosstalk occurs (the digital line terminating device 41 transmits to the ISDN line) based on such a timing signal, and An error signal is given to the SN ratio measurement unit 18. The SN ratio measurement unit 18 converts the error signal into an SN ratio (hereinafter referred to as “high noise interval SN ratio”).
[0026] 一方、 SN比測定部 14は、上記「高雑音区間」である力否かにかかわらず、既述の 誤差信号の SN比（以下、「平均 SN比」という。）を定常的に求める。 On the other hand, the S / N ratio measurement unit 14 steadily calculates the S / N ratio (hereinafter referred to as “average S / N ratio”) of the error signal described above, regardless of the power of the “high noise interval”. Ask.
差分判定部 15は、これらの「平均 SN比」と「高雑音区間 SN比」との差 Δ ( >0)を求 める（図 2ステップ Sl)。さらに、差分判定部 15は、その差 Δが既定の閾値 TH ( >0) を上回る場合には、例えば、「所望の伝送品質 (SN比）が既定の余裕度で確保され 、し力も、伝送速度が無用に低下しない」との条件 (以下、「語長設定条件」という。 ) が「高雑音区間 SN比」に対して成立する値に、「シンボル長」を設定する（図 2ステツ プ S2)。しかし、上記の差 Δが閾値 THを下回る場合には、差分判定部 15は、「平均 SN比」の下で既述の「語長設定条件」を満たす値に、「シンボル長」を設定する（図 2 ステップ S3)。ビット数換算部 19は、送信部 10Tを介して ATU-C32宛に、その「シ ンボル長」を通知する。 [0027] すなわち、「シンボル長」は、「高雑音区間 SN比」が「平均 SN比」より閾値 TH以上 低い期間には、その「高雑音区間 SN比」に基づいて設定されるが、その他の期間に は、「平均 SN比」に基づいて設定される。 The difference determination unit 15 obtains a difference Δ (> 0) between these “average SN ratio” and “high noise interval SN ratio” (step Sl in FIG. 2). Further, if the difference Δ exceeds a predetermined threshold TH (> 0), the difference determination unit 15 may, for example, say that “desired transmission quality (SN ratio) is ensured with a predetermined margin and the force is also transmitted. “Symbol length” is set to a value that satisfies the condition that “the speed does not decrease unnecessarily” (hereinafter referred to as “word length setting condition”) with respect to the “high noise section SN ratio” (step in FIG. 2) S2). However, if the difference Δ is less than the threshold TH, the difference determination unit 15 sets the “symbol length” to a value that satisfies the above-mentioned “word length setting condition” under the “average SN ratio”. (Figure 2 Step S3). The bit number conversion unit 19 notifies the “symbol length” to the ATU-C32 via the transmission unit 10T. That is, the “symbol length” is set based on the “high noise interval SN ratio” during the period when the “high noise interval SN ratio” is lower than the “average SN ratio” by a threshold TH or more. This period is set based on the “average signal-to-noise ratio”.
したがって、「高雑音区間 SN比」と「低雑音区間 SN比」との双方を求めて「シンポ ル長」を設定する第一の従来例に比べて、演算手順の簡略化および処理量の削減 が図られる。さらに、「低雑音区間」と「高雑音区間」との識別が全く行われない第二 の従来例と特許文献 1、 2とに比べて、「伝送速度の無用な低下」と「伝送品質にかか わる余裕度の不足」との双方が軽減される。  Therefore, the calculation procedure is simplified and the amount of processing is reduced compared to the first conventional example in which both the “high noise interval SN ratio” and the “low noise interval SN ratio” are determined and the “symbol length” is set. Is planned. Furthermore, compared with the second conventional example and Patent Documents 1 and 2 where no distinction is made between “low noise section” and “high noise section”, “unnecessary reduction in transmission speed” and “transmission quality”. Both “insufficient margins” are alleviated.
[0028] このように本実施形態によれば、既述の「デュアルビットマップ方式」のような複雑な 技術が用いられることなぐ容易に安定性が確保され、かつ総合的なパフォーマンス の維持および向上が図られる。 As described above, according to the present embodiment, stability is easily ensured without using a complicated technique such as the “dual bit map method” described above, and overall performance is maintained and improved. Is planned.
さらに、 VDSL回線に本発明が適用された場合には、 ISDN回線によって周期的 に受ける干渉のレベルは ADSL回線が同様に受ける干渉のレベルほど大きくはなく 、かつ「高雑音区間 SN比」と「平均 SN比」との差が 1. 5デシベル以下であることが期 待できる。したがって、安定性が確保され、かつ総合的なパフォーマンスが向上する と共に、伝送速度が十数メガビット Z秒程度増加する可能性が高 、。  Furthermore, when the present invention is applied to a VDSL line, the level of interference periodically received by the ISDN line is not as great as the level of interference similarly received by the ADSL line, and the “high noise interval SN ratio” and “ The difference from the “average signal-to-noise ratio” can be expected to be 1.5 dB or less. Therefore, stability is ensured and overall performance is improved, and the transmission speed is likely to increase by more than a dozen megabits per second.
[第二の実施形態]  [Second Embodiment]
図 3は、本発明の第二の実施形態の動作を説明する図である。  FIG. 3 is a diagram for explaining the operation of the second embodiment of the present invention.
[0029] 以下、図 1および図 3を参照して本発明の第二の実施形態の動作を説明する。 Hereinafter, the operation of the second embodiment of the present invention will be described with reference to FIG. 1 and FIG.
本実施形態の特徴は、閾値 THが下記の通りに選定される点にある。  The feature of this embodiment is that the threshold TH is selected as follows.
本実施形態では、図 3に時間軸と並行な 2本の破線として示すように、既述の「語長 設定条件」の下で、「シンボル長」が所望の値 K ( >0)、（K-1)にそれぞれ設定され るための最小の SN比が予め求められる。なお、ここでは、これらの最小の SN比 SN κ In the present embodiment, as shown by two broken lines parallel to the time axis in FIG. 3, the “symbol length” is a desired value K (> 0), ( The minimum signal-to-noise ratio to be set for each of K-1) is determined in advance. Here, these minimum SN ratios SN κ
、 SN については、実測と、「理論的な解析に基づく算術演算」と、「同様の解析に, SN, measured, "arithmetic operation based on theoretical analysis" and "similar analysis
K-1 K-1
基づくシミュレーション」との何れかの結果として求められると仮定する。  It is assumed that it is obtained as a result of any of “based simulation”.
[0030] さらに、閾値 ΤΗは、これらの最小の SN比 SN 、 SN の差 S ( = SN — SN >  [0030] Furthermore, the threshold ΤΗ is the minimum SN ratio SN, the difference between SN S (= SN — SN>
K K-1 K K-1 K K-1 K K-1
0)の半分の値（= δ Ζ2)に設定される。 0) is set to half the value (= δ Ζ2).
したがって、本実施形態によれば、図 3に示すように、「シンボル長」が上述した所 望の値 K、（K-l)の何れである場合にも、「高雑音区間」と「低雑音区間」との如何に かかわらず、安定した伝送品質 (SN比）の余裕度が確保される。 Therefore, according to the present embodiment, as shown in FIG. Regardless of the “high noise interval” or “low noise interval”, a margin of stable transmission quality (SN ratio) is ensured regardless of the desired value K or (Kl).
[0031] なお、本実施形態は、「シンボル長」が所望の 2通りの値 Κ、（Κ 1)の何れかである 場合に、本発明が適用されている。 In the present embodiment, the present invention is applied when the “symbol length” is any one of two desired values Κ and (Κ1).
しかし、本発明は、このような場合だけではなぐ例えば、「シンボル長」が設定され 得る範囲の全てまたは一部に適用されてもよい。  However, the present invention may be applied to all or part of the range in which the “symbol length” can be set, for example, in addition to such a case.
さらに、このような範囲では、既述の最小の SN比 SN 、SN に相当する 2つの S  Furthermore, in such a range, two Ss corresponding to the minimum SN ratios SN and SN described above
K K-1  K K-1
N比は、所望の値 Kの如何にかかわらず一定ではなぐその値 Kに応じて定まる異な つた値であってもよい。  The N ratio may be a different value determined depending on the value K which is not constant regardless of the desired value K.
[0032] また、上述した各実施形態では、「高雑音区間」と「低雑音区間」との周期および長 さが一定となっている力 本発明では、これらの周期および長さは一定でなくてもよい さらに、上述した各実施形態では、「シンボル長」が「1ビット」単位に異なる値に変 更される変調方式が適用された DMT方式に基づいてマルチキャリア伝送が行われ ている。  [0032] Further, in each of the above-described embodiments, the force in which the period and the length of the "high noise section" and the "low noise section" are constant. In the present invention, these periods and lengths are not constant. Furthermore, in each of the above-described embodiments, multicarrier transmission is performed based on a DMT scheme to which a modulation scheme in which “symbol length” is changed to a different value in units of “1 bit” is applied.
[0033] しかし、本発明では、このような変調方式だけではなぐ例えば、個々のサブチヤネ ルに、シンボル長が「複数ビットの単位」で変更される変調方式が適用されてもよ!、。 また、上述した各実施形態では、「高雑音区間 SN比」と「低雑音区間 SN比」との何 れもがトレーニング信号のみについて計測されている。  [0033] However, in the present invention, for example, a modulation scheme in which the symbol length is changed in units of a plurality of bits may be applied to individual subchannels in addition to such a modulation scheme. Further, in each of the above-described embodiments, both the “high noise interval SN ratio” and the “low noise interval SN ratio” are measured only for the training signal.
しかし、本発明はこのような構成に限定されず、これらの SN比が所望の精度や実 時間性の下で得られるならば、如何なる信号にっ 、て計測されてもょ 、。  However, the present invention is not limited to such a configuration, and any signal can be measured as long as these S / N ratios can be obtained with a desired accuracy and real-time property.
[0034] さらに、上述した各実施形態では、「高雑音区間」と「低雑音区間」とで SN比が異な る要因は、「ピンポン伝送方式が適用され、かつ DSL回線と共通のケーブルを介して 収容された ISDN回線」によって生じる遠端漏話および近端漏話となって 、る。 しかし、このような要因は、例えば、外部から電磁波等として到来する干渉や外乱だ けではなぐ複数のエリアにおける芯線の柔軟な融通を実現するブリッジタップ等に お 、て生じる干渉や妨害であってもよ 、。 Furthermore, in each of the embodiments described above, the cause of the difference in the SN ratio between the “high noise section” and the “low noise section” is that the “ping-pong transmission method is applied and the DSL line is used via a common cable. Far-end crosstalk and near-end crosstalk caused by “accommodated ISDN lines”. However, such factors are, for example, interference and interference caused by interference coming from the outside as electromagnetic waves and bridge taps that realize flexible accommodation of core wires in multiple areas, not just disturbances. Moyo.
[0035] また、上述した各実施形態では、漏話等の干渉を受ける ADSL回線を宅内 40にお いて終端する ADSLターミナルユニット (ATU— R) 10に本発明が適用されている。 しかし、漏話その他に起因して伝送品質が低下する所望の回線を終端する回線終 端装置でなるならば、その回線を構成する物理的な伝送路の構成、適用された多元 接続方式や変調方式の如何にかかわらず、局内 30に設置された ADSLターミナル ユニット 32等にも、本発明は適用可能である。 [0035] In each of the above-described embodiments, an ADSL line that receives interference such as crosstalk is installed in the home 40. The present invention is applied to an ADSL terminal unit (ATU-R) 10 that terminates in this manner. However, if it is a line terminator that terminates a desired line whose transmission quality deteriorates due to crosstalk or the like, the configuration of the physical transmission path that constitutes the line, the applied multiple access method and modulation method, etc. Regardless of the case, the present invention is also applicable to the ADSL terminal unit 32 installed in the station 30.
[0036] さらに、上述した各実施形態では、「高雑音区間」と「低雑音区間」との識別が局内 装置との連係の下で行われて 、る。 Furthermore, in each of the above-described embodiments, the “high noise section” and the “low noise section” are identified in cooperation with the in-station device.
し力し、例えば、局内 30に備えられた ADSLターミナルユニット 32のように、 ISDN 回線の状態を主導的に監視することによってにこれらの区間の識別を自立的に行う 装置にも、本発明は適用可能である。  However, the present invention can also be applied to a device that autonomously identifies these sections by leadingly monitoring the state of the ISDN line, such as the ADSL terminal unit 32 provided in the station 30. Applicable.
[0037] また、既述の「語長設定条件」そのものは本発明の特徴ではなぐ本発明の特徴は[0037] Further, the above-described "word length setting condition" itself is not a feature of the present invention.
、「高雑音区間 SN比」と「平均 SN比」との何れかが「このような語長設定条件を満た すべき SN比」として適用されること〖こよって、「シンボル長」が設定される点にある。 さらに、上述した各実施形態では、既述の DMT方式が適用された ADSL回線を終 端する回線終端装置に本発明が適用されて 、る。 Therefore, either “high noise interval SN ratio” or “average SN ratio” is applied as “SNR that should satisfy these word length setting conditions”, so that “symbol length” is set. There is in point. Further, in each of the above-described embodiments, the present invention is applied to a line terminating device that terminates an ADSL line to which the above-described DMT method is applied.
[0038] しかし、このような ADSL回線その他のディジタル加入者線を終端する回線終端装 置だけではなぐ例えば、マルチキャリア伝送に代えて、あるいはマルチキャリア伝送 と共に多値伝送に用いられる回線を終端する回線終端装置にも、本発明は適用可 能である。 [0038] However, the line used for multi-level transmission is terminated instead of multi-carrier transmission or together with multi-carrier transmission. The present invention can also be applied to a line termination device.
また、多値伝送に用いられる回線を終端する回線終端装置に本発明が適用された 場合には、既述の「シンボル長」に代えて、その多値伝送を実現する変調方式にか かわるシンボルの数または信号点配置が変更されてもよい  In addition, when the present invention is applied to a line terminator that terminates a line used for multilevel transmission, a symbol related to a modulation scheme that realizes the multilevel transmission instead of the above-described “symbol length”. Number or signal point arrangement may be changed
さらに、上述した各実施形態では、「高雑音区間 SN比」または「平均 SN比」が「語 長設定条件」を満たす値に「シンボル長」が設定されて!ヽる。  Further, in each of the above-described embodiments, “symbol length” is set to a value satisfying “word length setting condition” for “high noise interval SN ratio” or “average SN ratio”.
[0039] しかし、このような「語長設定条件」が成立する SN比は、例えば、「ビット誤り率 (伝 送路復号ィ匕の過程で検出されるものを含む。）」、「シンボル単位における信号点の 誤差」、「アイパターンとして観測されたアイアパーチャ」のように、広義の多様な伝送 品質で代替可能である。 また、上述した実施形態に限定されるものではなぐ本発明の範囲において多様な 実施形態が可能であり、かつ構成装置の全てまたは一部に如何なる改良が施されて ちょい。 [0039] However, the S / N ratio satisfying such a "word length setting condition" is, for example, "bit error rate (including that detected in the process of channel decoding)", "symbol unit" It can be replaced with a wide variety of transmission qualities, such as “Error of signal point in” and “Eye aperture observed as eye pattern”. In addition, various embodiments are possible within the scope of the present invention, not limited to the above-described embodiments, and any improvements may be made to all or part of the constituent devices.
産業上の利用可能性 Industrial applicability
本発明が適用された通信システムや伝送システムでは、予め想定可能な干渉の程 度や形態に対する柔軟な適応が可能となり、かつサービス品質および信頼性が向上 すると共に、安定に維持される。  The communication system and transmission system to which the present invention is applied can flexibly adapt to the degree and form of interference that can be assumed in advance, improve service quality and reliability, and maintain stability.

Claims

請求の範囲 The scope of the claims
[1] 間欠的に干渉を受け、かつマルチキャリア伝送に用いられる回線を終端する回線 終端装置において、  [1] In a line termination device that receives interference intermittently and terminates the line used for multicarrier transmission,
前記回線を介して受信される信号の伝送品質の平均値と、前記伝送品質が前記干 渉に応じて劣化した劣化伝送品質とを求める伝送品質監視手段と、  Transmission quality monitoring means for obtaining an average value of transmission quality of a signal received via the line and a deteriorated transmission quality in which the transmission quality is degraded according to the interference;
前記平均値と前記劣化伝送品質との差が既定の閾値を上回る場合には、前記劣 化伝送品質を基準として、前記マルチキャリア伝送を実現する個々のキャリアを介し て伝送されるシンボルのサイズを設定し、かつ前記差が前記既定の閾値を下回る場 合には、前記平均値を基準として前記シンボルのサイズを設定する制御手段と を備えたことを特徴とする回線終端装置。  If the difference between the average value and the deteriorated transmission quality exceeds a predetermined threshold, the size of a symbol transmitted via each carrier that realizes the multicarrier transmission is determined based on the deteriorated transmission quality. And a control unit configured to set a size of the symbol on the basis of the average value when the difference is less than the predetermined threshold value.
[2] 請求項 1に記載の回線終端装置において、  [2] In the line termination device according to claim 1,
前記伝送品質監視手段は、  The transmission quality monitoring means includes
前記回線の伝送特性の評価に用いられる既知の信号について、前記伝送品質の 平均値と、前記劣化伝送品質とを求める  Obtain an average value of the transmission quality and the deteriorated transmission quality for a known signal used for evaluating the transmission characteristics of the line.
ことを特徴とする回線終端装置。  A line termination device characterized by that.
[3] 請求項 1に記載の回線終端装置において、 [3] In the line termination device according to claim 1,
前記既定の閾値は、  The predetermined threshold is
前記シンボルのサイズが既定の単位増加することが許容される前記伝送品質の増 分の半分の値である  The symbol size is half the increment of the transmission quality that is allowed to increase by a predetermined unit.
ことを特徴とする回線終端装置。  A line termination device characterized by that.
[4] 間欠的に干渉を受け、かつ多値伝送に用いられる回線を終端する回線終端装置 において、 [4] In a line terminating device that intermittently receives interference and terminates the line used for multilevel transmission,
前記回線を介して受信される信号の伝送品質の平均値と、前記伝送品質が前記干 渉に応じて劣化した劣化伝送品質とを求める伝送品質監視手段と、  Transmission quality monitoring means for obtaining an average value of transmission quality of a signal received via the line and a deteriorated transmission quality in which the transmission quality is degraded according to the interference;
前記平均値と前記劣化伝送品質との差が既定の閾値を上回る場合には、前記劣 化伝送品質を基準として前記多値伝送を実現するシンボルの数またはサイズを設定 し、前記差が前記既定の閾値を下回る場合には、前記平均値を基準として前記シン ボルの数またはサイズを設定する制御手段と を備えたことを特徴とする回線終端装置。 When the difference between the average value and the deteriorated transmission quality exceeds a predetermined threshold value, the number or size of symbols for realizing the multi-value transmission is set based on the deteriorated transmission quality, and the difference is set to the predetermined value. Control means for setting the number or size of the symbols on the basis of the average value. A line termination device comprising:
[5] 請求項 4に記載の回線終端装置において、 [5] In the line termination device according to claim 4,
前記伝送品質監視手段は、  The transmission quality monitoring means includes
前記回線の伝送特性の評価に用いられる既知の信号について、前記伝送品質の 平均値と、前記劣化伝送品質とを求める  Obtain an average value of the transmission quality and the deteriorated transmission quality for a known signal used for evaluating the transmission characteristics of the line.
ことを特徴とする回線終端装置。  A line termination device characterized by that.
[6] 請求項 4に記載の回線終端装置において、 [6] In the line termination device according to claim 4,
前記既定の閾値は、  The predetermined threshold is
前記シンボルの数または語長が既定の単位増加することが許容される前記伝送品 質の増分の半分の値である  The number of symbols or word length is half of the transmission quality increment allowed to increase by a predetermined unit
ことを特徴とする回線終端装置。  A line termination device characterized by that.
[7] 間欠的に干渉を受け、かつマルチキャリア伝送に用いられる回線を介して受信され る信号の伝送品質の平均値と、前記伝送品質が前記干渉に応じて劣化した劣化伝 送品質とを求め、 [7] An average value of transmission quality of a signal that is intermittently interfered and received via a line used for multicarrier transmission, and a deteriorated transmission quality in which the transmission quality is deteriorated in accordance with the interference. Seeking
前記平均値と前記劣化伝送品質との差が既定の閾値を上回る場合には、前記劣 化伝送品質を基準として、前記マルチキャリア伝送を実現する個々のキャリアを介し て伝送されるシンボルのサイズを設定し、かつ前記差が前記既定の閾値を下回る場 合には、前記平均値を基準として前記シンボルのサイズを設定する  When the difference between the average value and the deteriorated transmission quality exceeds a predetermined threshold value, the size of a symbol transmitted via each carrier that realizes the multicarrier transmission is determined based on the deteriorated transmission quality. If the difference is less than the predetermined threshold, the symbol size is set based on the average value.
ことを特徴とする伝送制御方法。  A transmission control method characterized by the above.
[8] 間欠的に干渉を受け、かつ多値伝送に用いられる回線を介して受信される信号の 伝送品質の平均値と、前記伝送品質が前記干渉に応じて劣化した劣化伝送品質と を求め、 [8] An average value of transmission quality of a signal that is intermittently interfered and received via a line used for multilevel transmission and a deteriorated transmission quality in which the transmission quality is deteriorated in accordance with the interference are obtained. ,
前記平均値と前記劣化伝送品質との差が既定の閾値を上回る場合には、前記劣 化伝送品質を基準として前記多値伝送を実現するシンボルの数またはサイズを設定 し、前記差が前記既定の閾値を下回る場合には、前記平均値を基準として前記シン ボルの数またはサイズを設定する  When the difference between the average value and the deteriorated transmission quality exceeds a predetermined threshold value, the number or size of symbols for realizing the multi-value transmission is set based on the deteriorated transmission quality, and the difference is set to the predetermined value. If the value is below the threshold, set the number or size of the symbols based on the average value.
ことを特徴とする伝送制御方法。  A transmission control method characterized by the above.
PCT/JP2005/003598 2005-03-03 2005-03-03 Line terminating apparatus and transmission control method WO2006092861A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001298499A (en) * 2000-04-17 2001-10-26 Fujitsu Ltd Digital subscriber line transmission method and transmitter and transmitter-receiver under periodic noise environment
JP2004007270A (en) * 2002-05-31 2004-01-08 Panasonic Communications Co Ltd Adsl modem apparatus, adsl communication apparatus, and synchronization adjustment method for adsl communication
JP2004032753A (en) * 2003-06-16 2004-01-29 Fujitsu Ltd DIGITAL SUBSCRIBER LINE TRANSMISSION METHOD AND xDIGITAL SUBSCRIBER LINE APPARATUS

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001298499A (en) * 2000-04-17 2001-10-26 Fujitsu Ltd Digital subscriber line transmission method and transmitter and transmitter-receiver under periodic noise environment
JP2004007270A (en) * 2002-05-31 2004-01-08 Panasonic Communications Co Ltd Adsl modem apparatus, adsl communication apparatus, and synchronization adjustment method for adsl communication
JP2004032753A (en) * 2003-06-16 2004-01-29 Fujitsu Ltd DIGITAL SUBSCRIBER LINE TRANSMISSION METHOD AND xDIGITAL SUBSCRIBER LINE APPARATUS

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