WO2000030316A1 - Procede et dispositif de detection de section de bruit periodique dans un systeme de transmission en ligne d'abonne numerique - Google Patents

Procede et dispositif de detection de section de bruit periodique dans un systeme de transmission en ligne d'abonne numerique Download PDF

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Publication number
WO2000030316A1
WO2000030316A1 PCT/JP1999/006340 JP9906340W WO0030316A1 WO 2000030316 A1 WO2000030316 A1 WO 2000030316A1 JP 9906340 W JP9906340 W JP 9906340W WO 0030316 A1 WO0030316 A1 WO 0030316A1
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WIPO (PCT)
Prior art keywords
signal
noise section
subscriber line
communication
digital subscriber
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PCT/JP1999/006340
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English (en)
Japanese (ja)
Inventor
Nobukazu Koizumi
Hiroyasu Murata
Atsushi Sakurai
Yasuhiro Arai
Takashi Sasaki
Kazutomo Hasegawa
Yutaka Awata
Seiji Miyoshi
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Fujitsu Limited
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Publication of WO2000030316A1 publication Critical patent/WO2000030316A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/02—Details
    • H04B3/46—Monitoring; Testing
    • H04B3/487—Testing crosstalk effects

Definitions

  • the present invention relates to a digital subscriber line transmission system that transmits a high-speed data signal while coexisting with a telephone voice signal using a metallic line (hereinafter, referred to as a subscriber line) generally called a telephone line.
  • a subscriber line a metallic line
  • XDSL Digital Sub-scriber Line
  • XDSL digital subscriber line transmission systems
  • AD SL asymmetric transmission
  • Asymmetric DSL asymmetric transmission
  • the center and the user's home are connected by a metallic line made of copper wire, and the center is connected to a switch and a center modem via a splitter that separates the signal from the line according to the frequency. And are connected in parallel.
  • This splitter allows a signal in a low frequency band of approximately 4 kHz or less used for telephone voice and a high frequency band used for modulation and demodulation by a system for ADSL communication (that is, a center modem in this case). Signal is separated. With such signal separation, the exchange and the center modem can function as mutually independent communication systems.
  • a splitter is connected to the metallic line at the user's home.
  • a well-known telephone used for general voice communication and a system for ADSL communication ie, a home modem in this case
  • the home modem is usually connected to an information processing device such as a personal computer (PC). Or built-in.
  • PC personal computer
  • a splitterless ADSL system is also being studied. ing.
  • the xDSL technology enables a conventional telephone signal and high-speed data transmission to coexist on the same physical transmission medium.
  • users who use the network from the user's home need to lay a new dedicated communication line for high-speed data communication, such as ISDN, or to install a large-scale on existing metallic line (telephone line) facilities. It is expected that the user will be able to enjoy high-speed digital transmission services independent of the existing telephone services at relatively low V and cost without making any major changes.
  • the digital signal transmission technology used for ADS L is a single carrier wave, which carries out high-speed data communication using one carrier (carrier) for each of the upstream and downstream signals, called CAP (Carrierless Amplitude Phase Modulation).
  • CAP Carrierless Amplitude Phase Modulation
  • DMT Discrete Multitone Transmission
  • FIG. 7 is a diagram illustrating a periodic crosstalk noise environment.
  • OCU on the station side, OCU is an ISDN station unit, ATU-C is a station ADSL device, and on the subscriber side, DSU is an ISDN subscriber unit, and ATU-R is a subscriber ADSL device.
  • each opposing device is connected on a metallic line.
  • the line between the OCU and DSU is called an ISDN line
  • the line between ATU-C and ATU-R is called an ADSL line.
  • Communication between OCU / / DSU on I SDN line is carried out so-called ping-pong transmission. That is, the time period of the 2.5 ms frame period is This is used as the data transmission timing for downlink (from the station to the subscriber).
  • the ADS L line adjacent to the ISDN line is affected by crosstalk noise from the ISDN line.
  • Crosstalk noise from the ISDN as viewed from the ADSL strongly affects the transmission timing of the closer ISDN device as viewed from a certain ADSL device (for example, DSU as viewed from the ATU-R). This is called near-end cross talk (NEXT).
  • NEXT near-end cross talk
  • FEXT far-end crosstalk
  • the S / N of the DMT-modulated signal (hereinafter simply referred to as DMT symbol) on the ADSL line is likely to deteriorate, and is affected by FEXT.
  • SZN is relatively good in the section (hereinafter simply referred to as the low noise section).
  • the 803 Otsu line is affected by periodic crosstalk noise from one SDN line.
  • a noise environment is called a periodic crosstalk noise environment.
  • the DMT modulation type AD SL transceiver has a bit map that determines bit assignment to each carrier for DMT symbols for transmission and reception.
  • these transmission / reception bitmaps are transmitted in a high noise section (NEXT: near end cross talk) and a low noise section (FEXT: far end). end cross talk) and using two each.
  • NEXT near end cross talk
  • FEXT far end noise section
  • DBM Dual Bit Map
  • FIG. 2 is a diagram illustrating bit assignment of DBMZSWB.
  • bit map (indicated by A or B in the figure) prepared in advance is selected according to the above noise interval, and bit assignment to each carrier is executed.
  • an ADSL device (ATU-C) on the station side will be described as an example.
  • ATU-C For each TCM-I SDN 400Hz time reference (1), each noise interval (2) exists.
  • the ADSL unit (ATU-C) on the station side applies the bitmap (4) corresponding to each noise interval to the DMT symbol (3) to be transmitted.
  • SWB sliding window bitmap
  • 345 DMT symbols (# 0 to # 344) are associated with 34 times (# 0 to # 33) of the TCM-ISDN timing reference (400 Hz), and a hyper frame (Hyper Frame) ) Is defined.
  • the transmitting ADSL device (ATU-C / R) is used according to the sliding window for identifying the symbol at the timing to be reliably received in the FEXT section of the receiving side among the symbols in the hyperframe. To send a DMT symbol.
  • Both the DB MZ SWB assume that the subscriber line used for communication is in an environment that is affected by, for example, periodic noise from TCM-ISDN. Therefore, the DBM / SWB measures the S / N of the NEXT side and the FEXT side at the start of communication, etc., and allocates bit maps based on a certain reference (for example, S / N margin).
  • the noise environment of AD SL is considered from another viewpoint.
  • ISDN in the United States constantly transmits and receives signals even when there is no data from the user to be transmitted, and sends random data. This is called the always-on type. In the case of this always-on connection type, there is little change in the noise environment unless a new ISDN subscriber joins a nearby line.
  • TCM-ISDNs transmit and receive signals only while a call is occurring, such as the call by call method in Japan.
  • the ISDN line adjacent to the AD SL line is specified, every time the ISDN subscriber communicates, the ADSL subscriber line adjacent to that line Crosstalk noise from the ISDN is generated intermittently by the user, and the transmission rate on the ADSL side deteriorates.
  • the S / N measured at this time in both the NEXT section and FEXT section A predetermined S / N margin is set based on the N characteristic value.
  • This function performs a process of storing and reusing the parameters during communication of the ADSL transceiver in advance for each line state. That is, when the state of the line changes, a parameter whose state is close to the state after the change is searched from the previously stored parameters. If a similar state exists, the parameter is set as a parameter of the transceiver. The communication is started.
  • the set of stored parameters is called a profile. For example, G.lite, one of the splitterless ADSL communication systems, is defined to store up to 16 types of profiles.
  • splitterless ADSL communication systems such as G.lite are assumed to be used in PCs. Therefore, in order to reduce power consumption, the use of a function that suppresses internal circuit operation as much as possible without transmitting a transmission signal during non-communication is being studied.
  • This function is called the Power Management function, especially for devices that need to reduce power consumption, such as portable personal computers.
  • This is a very important function. That is, for example, the power management function of the ADSL transceiver mounted on a portable personal computer and supplied with power is consumed by powering down the ADSL transceiver when the personal computer is used but not communicating. It plays a role in lowering the power and increasing the battery operating time of the personal computer.
  • Initialization is usually applied when ADSL communication is started from an initial state, such as when the ADSL device is first turned on.
  • FIG. 6 is a diagram illustrating a Fast Retrain sequence initiated by a subscriber. Here, only the first part of the Fast Retrain sequence is shown.
  • a signal called R-RECOV is transmitted, and then C-RECOV is returned from the ATU-C side.
  • the C-1 RECOV signal contains a 276 kHz dedicated sine frequency signal for PLL synchronization and a 207 kHz sine signal for burst synchronization.
  • the signal C-REVERB-FR1 is received from the C-RECOV at the ATU-R, and the signal is used to perform PLL timing recovery and synchronization with the burst period.
  • the transmission time of the C-REC OV signal is short, and then it is necessary to use the REVERB signal transmitted as a random signal to synchronize the burst cycle.
  • this REVERB signal contains a single sine signal of 276 kHz for PLL synchronization, but does not include a signal dedicated to burst cycle synchronization.
  • ATU-R subscriber side ADSL device
  • the ATU-R side when implementing a Fast Retrain sequence in a crosstalk environment such as the TCM-ISDN crosstalk noise in Japan, the ATU-R side will need to reduce the TCM-ISDN crosstalk noise. It is necessary to detect the cycle (this is called the burst cycle), estimate the NEXT section and FEXT section, and transmit the signal in synchronization with the cycle. In addition, this bar Effective procedures and methods for detecting the strike period need to be provided.
  • FIG. 21 is a diagram illustrating a conventional transmission rate determination sequence. Here, only relevant parts of the sequence are shown.
  • the transmission rate is determined by the station-side ADSL device (ATU-C).
  • ATU.R the subscriber ADSL unit notifies the maximum downlink transmission capacity (hereinafter referred to as Bmax) before the station ADSL unit (ATU-C) determines the transmission rate. That is possible.
  • FIG. 22 is a diagram for explaining the delay caused by the buffer.
  • the notification of the maximum transmission capacity is performed in the same way even when ADSL communicates in a periodic noise environment.
  • the transmission rate differs between the NEXT section and the FEXT section depending on the amount of periodic crosstalk noise, but the transmission rate of the AD SL line as seen from the user (there is a part simply referred to as the user 'data' rate) is kept constant. There must be. Therefore, it is necessary to provide a buffer buffer to absorb such a difference in transmission rate for each noise section, and it is inevitable that a transmission delay is caused by the buffer.
  • the transmission delay due to the buffer mentioned above is up to about 5 mSec with current technology (up to about 4 mSec on the transmitting side only).
  • FIG. 27 is a diagram for explaining the relationship between the ADSL communication state and the ATM-Layer alarm state.
  • An object of the present invention is to solve the problems described above and to improve the reliability of communication in a periodic noise environment in a digital subscriber line transmission system. Disclosure of the invention
  • the present invention has the following features in ADSL communication using a DMT (Discrete MultiTone) modulation method under a periodic noise environment.
  • DMT Discrete MultiTone
  • the ADSL transceiver includes means for independently setting a reference for determining a communication condition for a NEXT noise section and a FEXT noise section.
  • the setting means includes, for example, management means for separately managing profiles for Fast Retrain, which are conventionally managed as a set, for FEXT and NEXT.
  • the ADSL transceiver executes an initialization procedure in which a temporal sequence length for performing PLL synchronization and noise section synchronization is variable at the time of a subscriber-activated Fast Retrain sequence. Provide a means to do so.
  • PLL synchronization and noise during Fast Retrain sequence execution Retrain processing can be executed reliably.
  • a noise section estimation method in a digital subscriber line transmission system wherein: 1) a step of extracting a notification signal corresponding to the noise section; and 2) the extracted notification signal.
  • the ADSL transceiver in the ADSL transceiver, there is provided a means for performing continuous transmission on the uplink and transmitting a burst signal on the downlink. As a result, the data transfer rate in the uplink direction can be constantly increased.
  • the transmission delay is minimized.
  • Means are provided for notifying together a transmittable second capacity value (B-FASTmax). As a result, transmission data delay can be reduced while maintaining the SWB frame configuration.
  • an ADSL transceiver comprises alarm suppression means for generating and sending an alarm state suppression cell to an ATM-Layer during the processing of an initialization procedure or a fast retrain procedure.
  • FIG. 1 is a functional block diagram showing a main part of a transceiver in a DMT modulation system. Here, only the transmitting unit and the receiving unit of the ADSL transceiver facing each other via the metallic line are shown.
  • FIG. 2 is a diagram illustrating the DBMZS WB method.
  • FIG. 3 is a diagram illustrating the definition of a noise interval of a received symbol during SN measurement.
  • FIG. 4 is a diagram showing SZN measurement for each periodic noise section.
  • FIG. 5 is a diagram illustrating the definition of a bitmap.
  • FIG. 6 is a diagram illustrating a conventional Fast Retrain sequence activated by a subscriber. Here, only the first part of the Fast Retrain sequence is shown.
  • FIG. 7 is a diagram illustrating a periodic crosstalk noise environment.
  • FIG. 8 is a diagram illustrating a Fast Retrain sequence initiated by a subscriber according to the present invention. Here, only the first part of the Fast Retrain sequence improved by the present invention is shown.
  • FIG. 9 is a diagram illustrating a method of notifying a periodic noise section.
  • FIG. 10 is a diagram illustrating a transmission pattern for each DMT symbol.
  • FIG. 11 is a diagram for explaining a symbol pattern definition for noise section notification at the time of initial training.
  • FIG. 12 is a diagram illustrating the transmission timing of the sequence switching symbol.
  • FIG. 13 is an overall block diagram of the 40 OHz synchronization section.
  • FIG. 14 is a diagram for explaining the spectrum in step 1.
  • FIG. 15 is a diagram for explaining the spectrum in step 2.
  • FIG. 16 is a diagram illustrating the spectrum in step 3.
  • FIG. 17 is a functional block diagram showing the configuration of the demodulation unit.
  • FIG. 18 is a functional block diagram showing the configuration of the waveform extraction unit.
  • FIG. 19 is a functional block diagram illustrating a configuration of the determination unit.
  • FIG. 20 is a diagram for explaining crosstalk from an ADSL line to an ISDN line.
  • FIG. 21 is a diagram illustrating a conventional transmission rate determination sequence. Here, only the first part of the sequence is shown.
  • FIG. 22 is a diagram for explaining the delay caused by the buffer.
  • FIG. 23 is a diagram illustrating a transmission rate determination sequence according to the present invention.
  • FIG. 24 is a diagram for explaining the delay reduction of the buffer.
  • FIG. 25 is a diagram for explaining the dual latency mode.
  • FIG. 26 is a diagram illustrating bit allocation in the dual latency mode.
  • FIG. 27 is a diagram for explaining the relationship between the ADSL communication state and the ATM-Layer alarm state.
  • FIG. 28 is a diagram for explaining the ATM-Layer alarm state avoidance method of the present invention.
  • FIG. 29 is a diagram illustrating the structure of a hyperframe. Here, a transmission frame pattern from the station side is illustrated.
  • a parallel-serial converter that also serves as a cyclic prefix addition unit.
  • FIG. 1 is a functional block diagram showing a main part of a transceiver in the DMT modulation method.
  • the opposing transmitting unit and receiving unit of a transceiver (transceiver) in an ADSL modem apparatus opposing via a metallic line are illustrated.
  • This figure functionally shows the configuration of an ADSL transceiver using the DMT modulation method, and when implemented, each function is usually configured by software on a DSP (Digital Signal Processor) chip.
  • DSP Digital Signal Processor
  • the S / N of the NEXT section and the FEXT section are individually measured as in the conventional case. Also, based on the S / N measurement results, determine the bitmap and gain table values for the FEXT section and the NEXT section, respectively.
  • the following points differ from the conventional operation. I do.
  • FIG. 3 is a diagram illustrating the definition of a noise interval of a received symbol during S / N measurement.
  • the subscriber unit performs S / N measurement to determine the maximum transmission capacity of its own device when starting communication.
  • this S / N measurement is performed for each noise interval (NEXT / FEX), so it is necessary to define a correct SN measurement interval for each noise interval.
  • the S / N measurement section is as shown in Fig. 3. Well defined. -In other words, when the first DMT symbol is synchronized with the head of the received 400 Hz, the interval for performing the S / N calculation for the n-th symbol is given by the following equation.
  • Received symbols that do not satisfy any of the conditions are excluded from S / N measurement.
  • the noise section By defining the noise section in this way, the noise level in each noise section can be accurately measured.
  • FIG. 4 is a diagram showing a means for performing SZN measurement for each periodic noise section.
  • Figure 4 shows the configuration of the AD SL transceiver in which the SZN margin for each periodic noise section is set independently.
  • the DMT symbol obtained as received data is demodulated by the demodulator 210 and compared with the reference 220.
  • the received data outputs a 40 Hz clock applied to the frequency divider 240 and phase-matched, and the phase determining unit 250 determines the phase of the periodic noise section based on this clock.
  • the error information obtained by comparison with the reference is distributed by the selector 260 according to the determination result of the reception phase determination unit 250 and is sent to the NEXT section S / N measuring instrument 270 or the FEXT section S / N. Input to N measuring device 280. Then, based on the S / N measured by each measuring instrument, the transmission bit number converter 290 outputs the number of bits bNEXT bFEXT in the NEXT / FEXT of each carrier. In this transmission bit number converter 290, an SN margin for each periodic noise section is set.
  • FIG. 5 is a diagram illustrating the definition of a bitmap.
  • the transmission quality only in the NEXT section due to the intermittent TCM.ISDN periodic crosstalk noise as described above.
  • measures are taken in advance to prepare for significant line quality deterioration, such as setting a large S / N margin for the NEXT section in advance.
  • the S / N margin in the FEXT section is about 6 dB, while the S / N margin in the NEXT section is about 12 dB, which is larger than that in the FEXT section. This means that the transmission capacity allocated to the NEXT section from the beginning is kept low.
  • FEC Forward Error Correction
  • FEC includes Reed-Solomon codes and interleaving, and its parameters S and R (Reed-Solomon) and D (interleaving) can be set separately for the NEXT section and the FEXT section.
  • S and R Random-Solomon
  • D interleaving
  • a value may be selected so that the error correction effect is sufficiently strong for the NEXT section compared to the FEXT section so that the channel quality may be deteriorated in advance.
  • Profiles for the FEXT section and the NEXT section can be numbered and managed as a set as in the past, and can also be managed separately. When a set is numbered and managed, if there are multiple ping-pong transmission lines that affect the ADSL line, the number of profiles tends to increase.
  • Profiles for the FEXT section and the NEXT section are independently numbered and managed, and the designation of the profile number at the time of Fast Retrain is separately designated for FEXT / NEXT.
  • FIG. 8 is a diagram illustrating a Fast Retrain sequence initiated by a subscriber according to the present invention. Here, only the first part of the Fast Retrain sequence improved by the present invention is shown.
  • the present invention proposes the following new Fast Retrain sequence in order to ensure the synchronization of the burst in the Fast Retrain sequence from the subscriber ADSL device (ATU-R) as described above. That is, when the Fast Retrain sequence from the subscriber ADSL device (ATU-R) is activated, the C-RECOV signal is continuously transmitted from the station ADSL device (ATU-C).
  • a new signal for transition to the REVERB signal is defined after the PLL synchronization and the last synchronization are established by the subscriber ADSL device (ATU-R) that receives this, and the subscriber ADSL is defined. Sent from the device (ATU-R). Then, after the signal is received by the station-side ADSL device (ATU-C), the state is changed to transmission of a REVERB signal.
  • ATU-R subscriber ADSL device
  • ATU-C station-side ADSL device
  • the signal that triggers this transition is defined as R—RE COV 2.
  • This signal is a single sine wave signal whose frequency is changed from R-RECOV.
  • the burst period can be ensured by the subscriber ADSL device (ATU-R).
  • ATU-R subscriber ADSL device
  • the NEXT section and the FEXT section are estimated, and signals can be transmitted in synchronization with the cycle.
  • the optical network unit shall notify the periodic noise section for the initial training of the subscriber unit (ATU-R).
  • ATU-C shall notify the periodic noise section for the initial training of the subscriber unit (ATU-R).
  • FIG. 9 is a diagram illustrating a method of notifying a periodic noise section.
  • FIG. 9 shows a transmission (notification) method of 400 Hz.
  • a carrier of a frequency that is less affected by periodic noise is selected as a signal for notifying the noise section.
  • FIG. 10 is a diagram illustrating a transmission pattern for each DMT symbol.
  • the noise section By transmitting two quaternary QAM symbols 90 ° out of phase alternately as a pattern corresponding to the noise section (FEXT / NEXT), the noise section can be notified.
  • points indicated by A and B are arrangement examples of the transmission pattern on the quaternary QAM coordinates.
  • FIG. 11 is a diagram for explaining a symbol pattern definition for notification of a noise section at the time of initial training.
  • FIG. 11 shows the definition of a noise section when the above-mentioned noise section notification is performed.
  • FIG. 12 is a diagram illustrating the transmission timing of the sequence switching symbol.
  • the ADSL device notifies the user of the transition to the next sequence with a certain number of switching display symbols.It is specified that the head of this switching symbol arrives at the FEXT section of the subscriber device. And make sure that the notice is given.
  • FIG. 13 is an overall block diagram of the 40 OHz synchronization section.
  • FIG. 14 is a diagram illustrating the spectrum in Procedure 1.
  • FIG. 15 is a diagram illustrating the spectrum in step 2.
  • FIG. 16 is a diagram illustrating the spectrum in step 3.
  • FIG. 17 is a functional block diagram showing the configuration of the demodulation unit.
  • FIG. 18 is a functional block diagram showing the configuration of the waveform extraction unit.
  • FIG. 19 is a functional block diagram illustrating a configuration of the determination unit.
  • the notification of the periodic noise section is transmitted using a carrier with a low noise frequency (for example, # 48: # 48).
  • a pilot tone is also transmitted for PLL synchronization.
  • Figures 13 to 19 show examples where the sampling frequency is 1.104 MHz.
  • carrier # 48 is extracted by a band pass filter B PF (procedure 1).
  • Fig. 14 shows the spectrum at this time.
  • the extracted signal is demodulated at the frequency of carrier # 48, and a vector signal is obtained (step 2). That is, the vector signal is the cosine signal
  • Figure 15 shows the spectrum after demodulation. -The demodulation can be performed using, for example, the demodulator shown in FIG.
  • the baseband signal is multiplied by the complex conjugate of a signal obtained by delaying the baseband signal (for example, by delaying 64 samples at 1.104 MHz sampling) (step 4).
  • the transition from FEXT to NEXT appears as -90 °
  • the transition from NEXT to FEXT appears as + 90 °.
  • This waveform extraction can be performed using, for example, a waveform extraction unit shown in FIG.
  • step 5 determine the transition by taking the sum of the real and imaginary axis components and the difference between the real and imaginary axis components (step 5). As a result, the judgment can be made with the code, and the noise can be expected to be slightly reduced.
  • the judgment method is
  • Real axis component + imaginary axis component is negative: FEXT ⁇ NEXT transition
  • Real axis component minus imaginary axis component is negative: NEXT ⁇ FEXT transition
  • the above determination can be made using, for example, a determination unit having the configuration shown in FIG.
  • circuit blocks of the demodulation unit and the waveform extraction unit shown in FIGS. 17 and 18 can be applied to the demodulation unit and the waveform extraction unit of the 400 Hz clock synchronization unit shown in FIG. 13, respectively. .
  • an effective procedure and processing method for detecting a burst period in a subscriber ADSL device (ATU-R) is provided.
  • FIG. 20 is a diagram illustrating crosstalk from an AD SL line to an ISDN line.
  • the effect of ADSL lines on TCM-ISDN lines Considering this, the effect on the downstream side is strong, while the effect on the upstream side is weak. -This is because the carrier frequency band used differs between the upstream signal and the downstream signal in the ADSL line.
  • the effect of NEXT section noise from AD SL to ISDN is relatively small.
  • the upstream (Upstream) side of ADSL using a low frequency band uses a continuous signal
  • the downstream (Downstream) side using a wide frequency band uses a downstream synchronized with TCM-ISDN.
  • the station-side ADSL device transmits data only in the FEXT section of the subscriber-side ADSL device (ATU-R), such as a symbol in a sliding window of the SWB.
  • the subscriber-side ADSL device transmits data during the NEXT and FEXT periods of the station-side ADSL device (ATU-C).
  • FIG. 29 is a diagram illustrating the structure of a hyperframe. Here, a transmission frame pattern from the station side is illustrated. In the figure, the shaded area indicates the symbol inside the sliding window (inside symbol), S and I indicate the synchronous symbol (synch symbol) and the synchronous symbol (inverse synch symbol), respectively, and the other symbols are the symbols outside the sliding window. ).
  • the ADSL frame of SWB has 3 4 5 DMT symbols (# 0 to # 33) for 34 times (# 0 to # 33) of TCM-ISDN timing reference (400Hz).
  • 344) is defined as a hyperframe.
  • the first to fourth DMT symbols corresponding to the first frame (# 0) are used as symbols in the sliding window.
  • the symbol in the sliding window is received in the FEXT section by the subscriber ADSL device (ATU-R) on the receiving side.
  • the symbols in the sliding window it can be seen that three to four DMT symbols are selected in each frame corresponding to the TCM-ISDN timing reference (400 Hz). This is to ensure that the receiving subscriber's ADSL device (ATU-R) receives the signal in the FEXT section (does not overlap with the NEXT section).
  • ATU-C central office
  • ATU-R subscriber
  • the present invention provides a process for reducing transmission delay by notifying the transmission capacity with the minimum transmission delay when the ATU-R notifies the maximum downlink transmission capacity Bmax in order to solve the above-mentioned delay problem. Suggest Tokor.
  • B-FASTmax the capacity that can be transmitted with the minimum transmission delay.
  • FIG. 23 is a diagram illustrating a transmission rate determination sequence according to the present invention.
  • the subscriber-side ADSL device determines the transmission rate before the station-side ADSL device (ATU-C) determines the transmission rate. Then, Bmax and B-FASTmax are calculated, and a message including Bmax and B-FASTmax is transmitted to the station-side ADSL device (ATU-C) at a message transmission timing after the random pattern.
  • FIG. 24 is a diagram for explaining the delay reduction of the buffer.
  • the symbols in the NEXT section vary from 5 to 7 symbols.
  • the transmission capacity (for example, the number of bits) when only three symbols in the FEXT section and five symbols in the NEXT section are transmitted is explicitly notified to the station side as B-FASTmax. Data is transmitted and received within this capacity B-FASTmax by the combination of symbols (3 symbols + 5 symbols). In this way, the fluctuation of the number of symbols transmitted in each frame of the hyperframe in each noise section is suppressed and kept constant, so that the number of symbols staying in the buffer is limited, thus reducing the delay of the buffer. It is possible to do so.
  • FIG. 25 is a diagram for explaining the dual latency mode.
  • ADSL there are two routes: a transmission route with a small transmission delay (hereinafter referred to as Fast Buffer) and a route with a large transmission delay to improve data quality (hereinafter called Interleaved Buffer). It supports a mode of transmitting route data together (hereinafter called dual 'latency mode').
  • FIG. 26 is a diagram for explaining bit allocation in the dual latency mode.
  • B-FASTmax Even in this dual latency mode, it is possible to reduce transmission delay using B-FASTmax. For example, Fast Buffer data is allocated to a certain number of bits within a range that can be allocated as B-FASTmax, and Interleaved Buffer data is allocated to the remaining bits and symbols.
  • the station-side ADSL device can reduce the transmission delay when the desired transmission rate is lower than B-FASTmax or when the transmission rate is lower than the transmission rate. For example, when it is desired to prioritize the transmission method, it is possible to select an optimal transmission method with reduced transmission delay.
  • the continuity check of the ATM-Layer is regarded as a disconnection when the USER cell or OAM cell (CC cell) for continuity check has not been traversed for 3 seconds ⁇ 0.5 seconds. Transition to the state.
  • Figure 28 shows a time chart for inserting pseudo CC cells during Fast Retrain.
  • the ADSL communication device (ATU-C / R) generates a CC cell in a pseudo manner until the ADSL communication (Layerl) determines that the subscriber line communication is impossible.
  • the ADSL communication Layerl
  • Fast Retrain processing is performed by off-hook of the telephone, etc., and there is no transition to the ATM-Layer power s alarm state while returning to the normal communication state.
  • ADSL communication (Layerl) cannot perform subscriber line communication
  • the point at which communication is determined to be impossible can be set when the Fast Retrain process fails, and the initial It is also possible to set the time of the failure of the process.
  • ATM-Layer the upper layer
  • the stability of ADSL users from the above layer is inadvertently degraded. Can be suppressed.
  • the function block diagram may be configured as an electronic circuit when mounted on the device, or may be configured as a software module on a DSP to perform the same function. Is also good.
  • the present invention has been variously described by way of preferred embodiments. However, the present invention is not limited to these embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention. Industrial applicability
  • the method and apparatus for detecting a periodic noise section in the digital subscriber line transmission system according to the present invention are extremely useful as a general-purpose transmission system that plays a core role with the expected increase in demand for network access. This is an effective technology.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Telephonic Communication Services (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
  • Data Exchanges In Wide-Area Networks (AREA)
  • Communication Control (AREA)
  • Noise Elimination (AREA)

Abstract

Dans un système de transmission en ligne d'abonné numérique, on améliore la fiabilité de communication dans un environnement à bruit périodique, au moyen d'un procédé et d'un dispositif de détection de section de bruit périodique. Des paramètres de référence (bNEXT, bFEXT) permettant la détermination desonditions de communication relatives à la section de bruit paradiaphonique (NEXT) et la section de bruit télédiaphonique (FXT) peuvent être fixés séparément. Des moyens (ATU-R, ATU-C) permettant l'exécution d'une procédure, lors du démarrage ou de l'arrêt de la communication, sont également prévus pour la confirmation de l'exécution (R-RECOV2) de la synchronisation des horloges et de la synchronisation de la section de bruit.
PCT/JP1999/006340 1998-11-16 1999-11-12 Procede et dispositif de detection de section de bruit periodique dans un systeme de transmission en ligne d'abonne numerique WO2000030316A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP32571198A JP3572964B2 (ja) 1998-11-16 1998-11-16 ディジタル加入者線伝送方法、局側ｘＤＳＬ装置及びｘＤＳＬ装置
JP10/325711 1998-11-16

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WO2000030316A1 true WO2000030316A1 (fr) 2000-05-25

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PCT/JP1999/006340 WO2000030316A1 (fr) 1998-11-16 1999-11-12 Procede et dispositif de detection de section de bruit periodique dans un systeme de transmission en ligne d'abonne numerique

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JP (1) JP3572964B2 (fr)
WO (1) WO2000030316A1 (fr)

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Publication number Priority date Publication date Assignee Title
TWI330021B (en) * 2003-07-25 2010-09-01 Panasonic Corp Communication network system, and transmission/reception apparatus, method and integrated circuit for use therein

Citations (3)

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Publication number Priority date Publication date Assignee Title
JPH11341153A (ja) * 1998-05-26 1999-12-10 Fujitsu Ltd ディジタル加入者線伝送システム
JP2000022838A (ja) * 1998-06-30 2000-01-21 Fujitsu Ltd 加入者線伝送システムの遅延抑制方式
JP2000031936A (ja) * 1998-05-08 2000-01-28 Nec Corp マルチキャリア伝送システム、マルチキャリア伝送装置及びマルチキャリア伝送方法

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JP2000031936A (ja) * 1998-05-08 2000-01-28 Nec Corp マルチキャリア伝送システム、マルチキャリア伝送装置及びマルチキャリア伝送方法
JPH11341153A (ja) * 1998-05-26 1999-12-10 Fujitsu Ltd ディジタル加入者線伝送システム
JP2000022838A (ja) * 1998-06-30 2000-01-21 Fujitsu Ltd 加入者線伝送システムの遅延抑制方式

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K. MATSUMOTO ET AL.: "ISDN rowa zatsuon sonzaiji no ADSL denso seinokaiseki kekka to seino kaizen hoho no ichi kento (Performance analysis of ADSL modems under the crosstalk noise from ISDN and a study of performance improvement)", TECHNICAL RESEARCH REPORT, THE INSTITUTE OF ELECTRONICS, INFORMATION AND COMMUNICATION ENGINEERS, CS98-37-47,, vol. 98, no. 147, 25 June 1998 (1998-06-25), pages 1 - 6, XP002929911 *
N. KOIZUMI ET AL.: "Pinpon rowa zatsuon kankyoka ni okeru ADSL tsushin hoshiki no ichi teian (An ADSL Transmission Technique under the TCM-ISDN Noise Environment)", LECTURE PROCEEDINGS DISTRIBUTED AT THE GENERAL MEETING ORGANIZED BY THE INSTITUTE OF ELECTRONICS, INFORMATION AND COMMUNICATION ENGINEERS, B-8-28,, 7 September 1998 (1998-09-07), pages 296, XP002929910 *

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JP3572964B2 (ja) 2004-10-06

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