WO2000052894A1 - Emetteur-recepteur a adaptation de debit basee sur le taux d'utilisation, pour modem lnpa - Google Patents

Emetteur-recepteur a adaptation de debit basee sur le taux d'utilisation, pour modem lnpa Download PDF

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Publication number
WO2000052894A1
WO2000052894A1 PCT/US1999/024458 US9924458W WO0052894A1 WO 2000052894 A1 WO2000052894 A1 WO 2000052894A1 US 9924458 W US9924458 W US 9924458W WO 0052894 A1 WO0052894 A1 WO 0052894A1
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WO
WIPO (PCT)
Prior art keywords
data
maximum
dataflow
dataflow rate
modem
Prior art date
Application number
PCT/US1999/024458
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English (en)
Inventor
Terry L. Cole
Original Assignee
Legerity, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Legerity, Inc. filed Critical Legerity, Inc.
Publication of WO2000052894A1 publication Critical patent/WO2000052894A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/04—Selecting arrangements for multiplex systems for time-division multiplexing
    • H04Q11/0428—Integrated services digital network, i.e. systems for transmission of different types of digitised signals, e.g. speech, data, telecentral, television signals
    • H04Q11/0478—Provisions for broadband connections
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0044—Arrangements for allocating sub-channels of the transmission path allocation of payload
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L7/00—Arrangements for synchronising receiver with transmitter
    • H04L7/04—Speed or phase control by synchronisation signals
    • H04L7/041—Speed or phase control by synchronisation signals using special codes as synchronising signal
    • H04L2007/045—Fill bit or bits, idle words
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/54—Store-and-forward switching systems 
    • H04L12/56—Packet switching systems
    • H04L12/5601—Transfer mode dependent, e.g. ATM
    • H04L2012/5614—User Network Interface
    • H04L2012/5616—Terminal equipment, e.g. codecs, synch.
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/54—Store-and-forward switching systems 
    • H04L12/56—Packet switching systems
    • H04L12/5601—Transfer mode dependent, e.g. ATM
    • H04L2012/5629—Admission control
    • H04L2012/5631—Resource management and allocation
    • H04L2012/5636—Monitoring or policing, e.g. compliance with allocated rate, corrective actions
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13034—A/D conversion, code compression/expansion
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13039—Asymmetrical two-way transmission, e.g. ADSL, HDSL
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13093—Personal computer, PC
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13166—Fault prevention
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13174—Data transmission, file transfer
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13196—Connection circuit/link/trunk/junction, bridge, router, gateway
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13199—Modem, modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13298—Local loop systems, access network

Definitions

  • This invention relates generally to communication systems, and, more particularly, to a transceiver with usage-based rate adaptation.
  • DSL technologies leave the POTS service undisturbed.
  • Traditional analog voice band interfaces use the same frequency band, 0-4 Kilohertz (kHz), as telephone service, thereby preventing concurrent voice and data use.
  • a DSL interface operates at frequencies above the voice channels from 100 kHz to 1.1 Megahertz (MHz).
  • MHz Megahertz
  • DSL systems use digital signal processing (DSP) to increase throughput and signal quality through common copper telephone wire.
  • DSL systems provide a downstream data transfer rate from the DSL Point-of-Presence (POP) to the subscriber location at speeds of about 1.5 Megabits per second (MBPS).
  • POP Point-of-Presence
  • MBPS Megabits per second
  • the transfer rate of 1.5 MBPS, for instance, is fifty times faster than a conventional 28.8 kilobits per second (KBPS) transfer rate.
  • DSL Digital Subscriber Line
  • One popular version of the DSL technology is the Asymmetrical Digital Subscriber Line (ADSL) technology.
  • the ADSL standard is described in ANSI T1.413 Issue 2, entitled, "Interface Between Networks and Customer Installation - Asymmetric Digital Subscriber Line (ADSL) Metallic Interface, Rev. R4, dated 6/12/98.
  • ADSL modems use two competing modulation schemes: discrete multi-tone (DMT) and carrierless amplitude/phase modulation (CAP).
  • DMT is the standard adopted by the American National Standards Institute.
  • the technology employed by DMT ADSL modems is termed discrete multi-tone.
  • the standard defines 256 discrete tones. Each tone represents a carrier signal that can be modulated with a digital signal for transmitting data.
  • the specific frequency for a given tone is 4.3125 kHz times the tone number.
  • Tones 1-7 are reserved for voice band and guard band (i.e., tone 1 is the voice band and tones 2-7 are guard bands). Data is not transmitted near the voice band to allow for simultaneous voice and data transmission on a single line.
  • the guard band helps isolate the voice band from the ADSL data bands.
  • a splitter may be used to isolate any voice band signal from the data tones.
  • Tones 8-32 are used to transmit data upstream (i.e., from the user), and tones 33-256 are used to transmit data downstream (i.e., to the user).
  • all the data tones 8-256 may be used for downstream data, and upstream data present on tones 8-32 would be detected using echo cancellation. Because more tones are used for downstream communication than for upstream communication, the transfer is said to be asymmetric.
  • the modems on both sides of the connection sense and analyze which tones are less affected by impairments in the telephone line. Each tone that is accepted is used to carry information.
  • the maximum capacity is set by the quality of the telephone connection.
  • the maximum data rate defined by the ADSL specification, assuming all tones are used, is about 8 MBPS downstream and about 640 KBPS upstream.
  • bits are allocated to different carriers according to a "loading" algorithm, such as the Water Filling (WF) algorithm or Equal Energy Distribution (EED) algorithm, for example.
  • the aforementioned loading algorithms utilize the signal-to-noise ratio (SNR) profile of a channel and a desired SNR margin to allocate bits.
  • SNR signal-to-noise ratio
  • carriers with higher SNR are able to carry more bits than those with lower SNR values.
  • increasing the desired margin reduces the number of bits that can be carried by a given carrier.
  • These loading algorithms typically attempt to establish either a maximum throughput or start with a predetermined throughput and distribute the bits required to support that throughput to the least impaired tones.
  • dynamic rate adaptation or bit swapping techniques may be used to change the bit rate in response to improving or degrading line conditions.
  • Current bit loading techniques suffer from at least one disadvantage in that they strive to maximize throughput at the expense of processing resources and power.
  • these modems employ powerful, but computationally taxing, algorithms, such as Trellis Coded Modulation (TCM), for example.
  • TCM Trellis Coded Modulation
  • TCM Trellis Coded Modulation
  • the present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
  • a transceiver including a receive unit and a usage monitoring unit.
  • the receive unit is adapted to receive data at a maximum dataflow rate.
  • the data includes actual data and idle cell data.
  • the usage monitoring unit is adapted to determine a usage parameter based on the actual data and adjust the maximum dataflow rate based on the usage parameter.
  • a method for adjusting a maximum dataflow rate of a transceiver.
  • the method includes receiving data.
  • the data includes actual data and idle cell data.
  • a usage parameter is determined based on the actual data.
  • the maximum dataflow rate is adjusted based on the usage parameter.
  • Figure 1 is a block diagram of a communications system in accordance with the present invention
  • Figure 2 is a simplified block diagram of a modem in accordance with the present invention
  • Figure 3 is a state diagram of a bit loading state machine for controlling the bit loading of data received by the modem of Figure 2
  • the communications system 10 includes a first modem 15 coupled to a second modem 20 through a connection 25
  • the second modem is part of a central office 30, and the connection 25 is an ordinary twisted pair connection, as is common m present-day telephone networks
  • the second modem 20 may not be part of the central office 30
  • the modems 15, 20 are described as they might be implemented under the ADSL protocol (ANSI Tl 413 Issue 2, entitled, "Interface Between Networks and Customer Installation - Asymmetric Digital Subscriber Line (ADSL) Metallic Interface, Rev R4, dated 6/12/98)
  • ADSL Digital Subscriber Line
  • the second modem 20 acts as a gateway to a larger communications network (not shown), such as a local or wide area network, or the Internet
  • a larger communications network such as a local or wide area network, or the Internet
  • the first modem 15 establishes a connection to the communications network (not shown) through the second modem 20
  • the first and second modems 15 and 20 complete a training process whereby an initial bit loadmg technique (e g , water filling, equal energy distribution, etc ) is employed to establish the throughput available for communication between the modems 15, 20
  • an initial bit loadmg technique e g , water filling, equal energy distribution, etc
  • the present invention is descnbed as it may be implemented m a modem, it is contemplated that, in light of this disclosure, the invention may be applied to any type of transceiver, including, but not limited to, a modem or some other wired or wireless communication device
  • a modem or some other wired or wireless communication device After training, data exchange between the modems 15, 20 commences Over time, one or both of the modems 15, 20 may monitor the transfer rate and adjust the bit loadmg m response to the dynamic throughput requirements
  • the throughput monitoring and adjustment is described as if the first modem 15 is monitoring the rate at which it receives data from the second modem 20 However, it is contemplated that either or both of the modems 15, 20 may cooperatively or independently monitor and adjust the throughput
  • FIG 2 a simplified block diagram of a modem 100 is provided The modem 100 may be the first modem 15 or the second modem 20
  • FIG. 1 a simplified block diagram of a modem 100 is provided
  • the modem 100 may be the
  • the modem 100 includes transmit, receive, and control functional blocks 105, 1 10, 1 15
  • the transmit block 105 includes a formatting and interfacing circuit 120 adapted to receive outgoing digital data over a data-out line 122
  • the formatting and interfacing circuit 120 performs functions such as cyclic redundancy checking
  • the transmit block 105 also includes a modulator 125 that receives data from the formatting and interfacing circuit 120 and modulates a carrier or carriers with the data
  • the modulator 125 performs tone ordering, constellation encoding, gain scaling, and an inverse discrete Fou ⁇ er transform (IDFT) function to provide time domam waveform samples
  • a second formatting and interfacing circuit 130 performs cyclic prefix insertion (/ e , a subset of the output samples from the modulator 125 is replicated and prepended to the existing output samples to provide an overlap and allow for better frame alignment) and buffers the samples received from the modulator 125
  • a digital to analog (D/A) converter and filter 135 converts the samples from the formatting and mterfacmg circuit 130 to an analog waveform suitable for transmission over the connection 25 through an external line interface 140
  • the receive block 110 includes an analog to digital (A/D) converter and filter 145 that receives an analog waveform over the connection 25 and samples the analog waveform to generate a time domam digital signal
  • a formatting and mterfacmg circuit 150 performs functions known in the art, such as frame alignment and time domam equalization In time domam equalization, because the tones are at different frequencies, certain frequencies travel faster than others, and as such, all the tones do not arrive at same time
  • the tune domam equalization function of the formatting and mterfacmg circuit 150 delays the faster tones to compensate for the propagation speed differences There is a performance trade off between the frame alignment and time domam equalization functions m that a higher degree of frame alignment accuracy allows a lesser degree of accuracy in time domain equalization
  • the cyclic prefix insertion performed by the mterfacmg modem (not shown) improves frame alignment accuracy
  • the formatting and mterfacmg circuit 150 also performs gam control to increase the
  • a demodulator 155 receives the time domam samples from the formatting and mterfacmg circuit 150 and converts the time domam data to frequency domam data
  • the demodulator 155 performs a slicing function to determine constellation points from the constellation encoded data, a demappmg function to map the identified constellation point back to bits, and a decodmg function (e g , Viterbi decoding if trellis constellation coding is employed)
  • the demodulator 155 also performs tone deorde ⁇ ng to reassemble the se ⁇ al bytes that were divided among the available tones
  • a second formatting and mterfacmg circuit 160 m the receive block 110 performs forward error correction, CRC checkmg, and descramb ng functions on the data received from the demodulator 155
  • the reconstructed data provided by the formatting and mterfacmg circuit 160 represents the sequential binary data that was sent by the mterfacmg
  • the reconstructed data is provided to a data-in line 165
  • the control block 115 includes a usage monitoring unit 170 adapted to monitor the peak and average dataflows of the data received by the receive block 1 10
  • the usage monitoring unit 170 includes a peak dataflow (PDFL) register 175 and an average dataflow (ADFL) register 180
  • PDFL peak dataflow
  • ADFL average dataflow
  • the average dataflow may be measured by the usage monitoring unit 170 using a fixed interval average (e g , a. rolling five minute average)
  • the specific amount of usage history used to generate the average dataflow is application specific, and may be configurable by the user or the central office 30.
  • the data received by the receive block 1 10 includes actual data and idle cells, the idle cells are used by the transmitting modem (not shown) to load the tones to capacity.
  • the receive block 110 discards the idle cells after receiving the data.
  • the usage monitoring unit 170 determines the average and peak dataflows based on the actual data (i.e., after the idle cells have been removed).
  • the operation of the usage monitoring unit 170 is illustrated using the diagram of a bit loading state machine 200 depicted in Figure 3.
  • the state machine 200 is entered in an establish data flow state 205.
  • the initial dataflow parameters are established during the training of the modem 100 using a bit loading pattern, such as, but not limited to a water filling algorithm or an equal energy distribution algorithm.
  • the number of bits allocated to the tones determines the maximum dataflow capacity.
  • the state machine 200 transitions from the establish data flow state 205 to a monitor dataflow state 210 when training of the modem 100 has completed.
  • the usage monitoring unit 170 populates the PDFL register 175 and the ADFL register 180 based on the dataflow of the received data. It is contemplated that the PDFL register
  • 175 may include the actual peak dataflow or, alternatively, the number of times in the current interval that the peak dataflow reaches the maximum dataflow. If the average dataflow over a monitoring period (e.g., five minutes) exceeds a threshold, such as, for example 70% of the maximum dataflow, the state machine 200 transitions to a increase bits state 215 where the maximum throughput is adjusted by increasing the number of bits on a tone or a number of tones. The method used to increase the number of bits to accomplish the dataflow adjustment is described below.
  • the state machine 200 may also transition to the increase bits state 215 if the peak dataflow is at the maximum dataflow for a predetermined time interval. For example, the peak dataflow reaches the maximum dataflow for three seconds. Alternatively, it is contemplated that the state machine 200 may transition to the increase bits state 215 if the peak dataflow reaches the maximum dataflow a predetermined number of times during the monitoring interval (i.e., 20 times in five minutes).
  • the thresholds described herein are provided for illustrative purposes. Various thresholding techniques are contemplated depending on the specific implementation. After increasing the number of bits, the state machine 200 transitions back to the monitor dataflow state
  • the state machine 200 may return to the increase bits state 215 to further increase the dataflow.
  • the usage monitoring unit 170 may also reduce the maximum dataflow if the user demand does not require such a bandwidth. If the average dataflow falls below a threshold, such as, for example 40% of the maximum dataflow for the monitoring interval, the state machine 200 transitions to a decrease bits state 220 where the maximum throughput is adjusted by decreasing the number of bits on a tone or a number of tones. Again, the method used to decrease the number of bits to accomplish the dataflow adjustment is described below.
  • the state machine 200 may also transition to the decrease bits state 220 if the peak dataflow is less than 90% of the maximum dataflow over the monitoring interval. Alternatively, if the peak dataflow reaches the maximum dataflow less than ten times in five minutes, the number of bits may be reduced.
  • the thresholds described herein are provided for illustrative purposes. Various thresholding techniques are contemplated depending on the specific implementation.
  • the usage monitoring unit 170 may choose to re- train the connection with a requested bit rate based on the values stored in the usage monitoring unit 170 and the
  • the state machine 200 transitions to a retrain state 230.
  • the modem 100 will attempt to train with the requested bit rate and restart the state machine 200 at the establish data flow state 205
  • the modem 100 may change the number of bits by issuing a bit swap request over the ADSL overhead channel (aoc)
  • a bit swap request is initiated in response to a change in the operating characteristics of the line (e g , increase or decrease in impairments)
  • the usage monitoring unit 170 may issue a bit swap to increase or decrease the number of bits in response to the peak and average dataflow parameters
  • usmg a dynamic rate adaptation configuration request message, the entire bit loadmg and gam tables used to configure the allocation of bits to all of the tones may be modified and sent by the modem 100 to change the dataflow rate Per the ADSL standard
  • DRA reconfiguration messages may also be sent using the aoc channel
  • An aoc message includes a message header (/ e , 11111111) that signals the modem 20 of the impending aoc message
  • the message header is followed by an 8-bit command field Per the ADSL standard, a command field value of 00000001 designates increasing the number of allocated bits by one and a command field value of 00000010 designates decreasing the number of allocated bits by one
  • the command field is followed by an 8-bit tone mdex designating the particular tone for which to change the number of bits
  • the ADSL standard also defines an extended bit swap request where the number of bits for a plurality of channels can be changed simultaneously
  • the extended bit swap request message mcludes a message header of
  • bit swap request message (; e , normal or extended) is repeated by the modem 15 five times within 400 ms of receivmg the bit swap request, the modem 20 at the central office 30 responds with a bit swap acknowledge message that mcludes a message header (e g , 11111111), an acknowledge command (e g ,
  • the usage monitoring unit 170 may choose to lower the number of bits on the more encumbered tones, or raise the number of bits on less encumbered tones
  • either or both modems 15, 20 may mdependently monitor the rate at which data is received
  • the modem 15 may mcrease an mcrease in its dataflow at the same time the modem 20 requests a dataflow decrease
  • the adaptive bit rate is limited on the top end by the characteristics of the connection (. e , the signal to noise ratio, desired margin for error rate, etc )
  • numerous advantages may be gamed
  • the number of bits per tone is reduced, the signal to noise margin is creased, and as a result, the error rate is decreased
  • the power required to transmit the tones may be reduced
  • Still more efficiency may be gamed by simplifying the modulation scheme in response to the lower dataflow
  • the mterfacmg modem may not be required to use constellation encodmg and/or trellis coding to mcrease the bit rate
  • the modem 100 receivmg the data would not be required to use a complex decoding method, such as
  • the decrease in complexity results in lower power and processing resource requirements, thereby increasing the efficiency of the communication. This could increase the battery life in a portable computer (not shown) using the modem 100, or could allow for increased modem sharing for the modem 20 in the central office 30.
  • a simplified block diagram of a computer system 300 is provided.
  • the computer system 300 includes a computer 305 coupled to a modem 310.
  • the modem 305 may be external to the computer 305, as illustrated, or alternatively, the modem 310 may be installed as an internal component of the computer 305.
  • the modem 305 operates in a similar manner to the modem 100 described above in reference to Figure 2, except that, in the embodiment of Figure 4, the computer 305 contains a usage monitoring unit 315 for monitoring the dataflow rate of the data received by the modem 310.
  • the usage monitoring unit 315 includes a peak dataflow register 320 and an average dataflow register 325 that are used in a similar manner as described above in reference to the modem 100 of Figure 2.
  • the computer 305 includes software that performs the usage monitoring and rate adaptation functions.
  • the peak and average dataflow registers 320, 325 may be general purpose registers or memory locations within the computer 305.
  • the computer 305 may instruct the modem 315 to adjust its bit rate or retrain based on the usage parameters determined by the usage monitoring unit 315.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Telephonic Communication Services (AREA)
  • Communication Control (AREA)

Abstract

Un émetteur-récepteur (100) comporte une unité de réception (110) et une unité de contrôle du taux d'utilisation (170). L'unité de réception (110) est conçue pour recevoir des données à un débit de données maximum. Les données comprennent des données réelles et des données de cellules de repos. L'unité de contrôle du taux d'utilisation (170) est conçue pour déterminer un paramètre de taux d'utilisation en fonction des données réelles et régler le débit de données maximum sur ledit paramètre de taux d'utilisation. Un procédé de réglage du débit de données maximum d'un émetteur-récepteur (100) est également décrit. Ledit procédé consiste à recevoir des données. Lesdites données comprennent des données réelles et des données de cellules de repos. Un paramètre de taux d'utilisation est déterminé en fonction des données réelles. Le débit de données maximum est réglé en fonction du paramètre de taux d'utilisation.
PCT/US1999/024458 1999-03-02 1999-10-18 Emetteur-recepteur a adaptation de debit basee sur le taux d'utilisation, pour modem lnpa WO2000052894A1 (fr)

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US20030117963A1 (en) * 2001-12-19 2003-06-26 Stmicroelectronics, Inc. Method and apparatus for application driven adaptive duplexing of digital subscriber loops
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Cited By (16)

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Publication number Priority date Publication date Assignee Title
EP1322101A2 (fr) * 2001-12-19 2003-06-25 STMicroelectronics, Inc. Minimisation de bruit diaphonique local et réduction de puissance pour des lignes d'abonné digitales numériques
US20030117963A1 (en) * 2001-12-19 2003-06-26 Stmicroelectronics, Inc. Method and apparatus for application driven adaptive duplexing of digital subscriber loops
EP1322101A3 (fr) * 2001-12-19 2005-01-05 STMicroelectronics, Inc. Minimisation de bruit diaphonique local et réduction de puissance pour des lignes d'abonné digitales numériques
US7103004B2 (en) * 2001-12-19 2006-09-05 Stmicroelectronics, Inc. Method and apparatus for application driven adaptive duplexing of digital subscriber loops
US7126984B2 (en) 2001-12-19 2006-10-24 Stmicroelectronics, Inc. Near-end crosstalk noise minimization and power reduction for digital subscriber loops
EP1322060B1 (fr) * 2001-12-19 2016-03-23 STMicroelectronics Inc Duplexage adaptatif pour lignes d'abonnés numériques
US8059704B2 (en) 2001-12-19 2011-11-15 Stmicroelectronics, Inc. Near-end crosstalk noise minimization and power reduction for digital subscriber loops
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