3
`
`Attorney's Docket No. __ 9...::...0_2_-_5_8_5 _____ _
`
`PATENT
`
`IN THE UNITED STATES PATENT AND TRADEMARK OFFICE
`
`In reapplication of: Etienne Vanzie1eghem et a1
`MULTI-CARRIER TELECOMMUNICATION SYSTEM
`For: WITH POWER ADAPTATION MEANS
`Box Provisional Patent Application
`Assistant Commissioner for Patents
`Washington, D.C. 20231
`
`COVER SHEET FOR FILING PROVISIONAL APPLICATION
`{37 C.F.R. § 1.51{2){i))
`
`WARNING:
`
`"A provisional application must also include a cover sheet identifying the application as a provisional
`application. Otherwise, the application will be treated as an application filed under§ 1.53(b)(1)."
`37 C.F.R. § 1.53(b)(2)(i).
`
`NOTE:
`
`NOTE:
`
`NOTE:
`
`NOTE:
`
`"A complete provisional application does not require claims since no examination on the merits will be
`given to a provisional application. However, provisional applications may be filed with one or more claims
`as part of the application. Nevertheless, no additional daim fee or multiple dependent daims fee will
`be required in a provisional application." Notice of December 5, 1994, 59 FR 63951, at 63953.
`"Any claim filed with a provisional application will, of course, be considered part of the original provisional
`application disclosure.· Notice of April 14, 1995, 60 Fed. Reg. 20,195, at 20,209.
`"A provisional application shall not be entitled to the right of priority under§ 1.55 or 35 U.S.C. 119
`or 365(a) or to the benefit of an earlier filing date under§ 1.78 or 35 U.S. C. 120, 121 or 365(c) of any
`other application." 37 C.F.R. § 1.53(b)(2)(iil).
`
`"No information disclosure statement may be filed in a provisional application." 37 C.F.R. § 1.51(2)(b).
`"Any information disdosure statements filed in a provisional application would either be returned or
`disposed of at the convenience of the Office." Noti'ce of December 5, 1994, 59 FR 63591, at 63594.
`
`"No amendment other than to make the provisional application comply with all applicable regulations,
`may be made to the provisional application after the filing date of the provisional application." 37 C.F.R.
`§ 1.53(b)(2).
`
`CERTIFICATION UNDER 37 CFR 1.10
`
`I hereby certify that this correspondence and the documents referred to as attached therein are being deposited
`with the United States Postal Service on Ju 1 Y 1 0 • 19 9 7
`(date), in an envelope as "EXPRESS MAIL
`POSTOFFICETOADDRESSEEn serviceunder37 C.F.R. 1.10, Mailing Label Number EMS 371 6 4 59 BITS
`n
`addressed to the: Assistant Commissioner for Patents, Washington, D.C. 2023b
`
`Gfrii/1 * kL tdl<
`
`NOTE: Each paper or fee filed by "Express Mail" must have the number of the "Express Mail" mailing label placed
`thereon prior to mailing. (.37 C.F.R. 1.10(b))
`
`WARNING: Certificate of mailing (first dass) or facsimile transmission procedures of 37 CFR 1.8(a) cannot be
`used to obtain a date of mailing or transmission for this correspondence. 37 C.F.R. 1.8(a)(i)(A)
`
`(type or print name of person certifying)
`
`(Cover Sheet for Filing Provisional Application [23-1]--page 1 of 5)
`
`

`
`WARNING: A provisional application may be abandoned by operation of 35 U.S. C. 111(b)(5) on a Saturday,
`Sunday, or Federal holiday within the District of Columbia, in which case, a nonprovisional
`application claiming benefit of the provisional application under 35 U.S. C. 119(e) must be filed no
`later than the preceding day that is not a Saturday, Sunday , or Federal holiday within the District
`of Columbia Notice of April14, 1995, 60 Fed. Reg. 20,195 at 20,202.
`This is a request for filing a PROVISIONAL APPLICATION FOR PATENT under 37 C.F.R.
`1.53(b)(2).
`1. The following comprises the information required by 37 C.F .R. § 1.51 (a)(2)(Q(A):
`2. The name(s) of the inventor(s} is/are (37 C.F.R. § 1.51 (a)(2)(Q(B)}:
`NOTE: While the name or names of the inventors are required in order to accord a provisional application a
`filing date, a provisional application is not required to be signed by the inventor or the assignee. No
`oath or declaration is required. Presumably, most provisional applications will be filed by a registered
`practitioner without a power of attorney being filed. Notice of December 5, 1994, 59 FR 63591, at 63594.
`"The naming of inventors for obtaining a filing date for a provisional application is the same as for other
`applications. A provisional application filed with the inventors identified as 'Jones et a/.' will not be
`accorded a filing date earlier than the date upon which the name of each inventor is supplied unless
`a petition with the fee set forth in § 1. 17(i) is filed which sets forth the reasons the delay in supplying
`the names should be excused. Administrative oversight is an acceptable reason. It should be noted
`that for a 35 U.S. C. 111 (a) application to be entitled to claim the beneftt of the filing date of a provisional
`application the 35 U.S.C. 111(a)[.J application must have at least one inventor in common with the
`provisional application." Notice of April 14, 1995, 60 Fed. Reg. 20,195, at 20,209.
`
`NOTE:
`
`The term "invention" is typically used to refer to subject matter which applicant is claiming in his/her
`application. Because claims are not required in a provisional application, it would not be appropriate
`to reference joint inventors as those who have made a contribution to the "invention" disclosed in the
`provisional application. If the "invention" has not been determined in the provisional application because
`no claims have been presented, then the name(s) of those person(s) who have made a contribution
`to the subject matter disclosed in the provisional application should be submitted. Section 1.45(c) states
`that "if multiple inventors are named in a provisional application, each named inventor must have made
`a contribution, individually or jointly, to the subject matter disclosed in the provisional application." All
`that § 1.45(c) requires is that if someone is named as an inventor, that person must have made a
`contribution to the subject matter disclosed in the provisional application. When applicant has
`determined what the invention is by the filing of the 35 U.S. C. 111(a) application, that is the time when
`the correct inventors must be named. The 35 U.S. C. 111 (a) application must have an inventor in common
`with the provisional application in order for the 35 U.S. C. 111(a) application to be entitled to claim the
`benefit of the provisional application under 35 U.S.C. 119(e). Notice of April 14, 1995, 60 Fed. Reg.
`20,195, at 20,208.
`
`"If all the names of the actual inventor or inventors are not supplied when the specification and any
`required drawings are filed, the provisional application will not be given a filing date earlier than the
`date upon which the names are supplied unless a petition, with the fee set forth in § 1. 17(q), is filed,
`which sets forth that the reasons for the delay in supplying the names should be excused." 37 C.F.R.
`§ 1.53(b)(2).
`
`1.
`
`2.
`
`3.
`
`Etienne
`GIVEN NAME
`
`Frank
`GIVEN NAME
`
`Peter
`GIVEN NAME
`
`MIDDLE INITIAL OR NAME
`
`Vanzieleghem
`FAMILY {OR LAST) NAME
`
`C.M.
`MIDDLE INITIAL OR NAME
`
`Defoort
`FAMILY (OR LAST) NAME
`
`P.F.
`MIDDLE INITIAL OR NAME
`
`Reusens
`FAMILY (OR LAST) NAME
`
`(Cover Sheet for Filing Provisional Application {23-1]--page 2 of 5)
`
`

`
`3. Address(es) of the inventor(s), as numbered above (37 C.F.R. § 1.51(a)(2)(Q{C)):
`1. Rue du Cochige 1, B-1360 Perwez, Belgium
`2. Beukenhoflaan 88 Bus 2, B-2630 Aartse1aar, Belgium
`
`3. Warande 121. B-9270 Laarne, Belgium
`
`4. The title of the invention is (37 C.F.R. § 1.51(a)(2)(i)(D)):
`MULTI-CARRIER TELECOMMUNICATION SYSTEM WITH POWER
`ADAPTATION MEANS
`
`5. The name, registration, and telephone number of the attorney (if applicable) is (37 C.F.R.
`§ 1.51 (a)(2)(i)(E)):
`Name of attorney:
`
`Reg. No.
`
`F ra n c i' s J
`31 , 3 91
`
`M a gn i re
`Tel. (203 -) 261-1234
`
`(complete the following, if applicable)
`
`0 A power of attorney accompanies this cover sheet.
`6. The docket number used to identify this application is (37 C.F.R. § 1.51 (a)(2)(Q(F)):
`
`902-585
`Docket No.:
`7. The correspondence address for this application is (37 C.F.R. § 1.51(a)(2)(Q(G)):
`Ware, Fressola, Van Der Sluys & Adolphson LLP
`755 Main Street, P.O. Box 224, Monroe, Connecticut 06468
`
`8. Statement as to whether invention was made by an agency of the U.S. Government
`or under contract with an agency of the U.S. Government.
`{37 C.F.R. § 1.51 (a){2)Q)(H))
`This invention was made by an agency of the United States Government, or under
`contract with an agency of the United States Government.
`[X No.
`0 Yes.
`The name of the U.S. Government agency and the Government contract number
`am: __________________________________________________ ___
`
`(Cover Sheet for Filing Provisional Application [23-1]--page 3 of 5)
`
`

`
`Identification of documents accompanying this cover sheet:
`9.
`A. Documents required by 37 C.F.R. §§ (a)(2WiHiii):
`
`Specification:
`
`No. of pages J 3
`3
`No. of sheets
`
`Drawings:
`B. Additional documents:
`No. of claims 13
`G} Claims:
`Note: A complete provisional application does not require claims. 37 C.F.R. § 1.51(a)(2).
`0 Power of attorney
`0 Small entity statement
`0 Assignment
`0 Other
`NOTE: Provisional applications may be filed in a language other than English as set forth in existing§ 1.52(d).
`However, an English language translation is necessary for security screening purposes. Therefore, the
`PTO will require the English language translation and payment of the fee mandated in§ 1.52{d) in the
`provisional application. Failure to timely submit the translation in response to a PTO requirement will
`result in the abandonment of the provisional application. If a 35 U.S. C. 111 (a) application is filed without
`providing the English language translation in the provisional application, the English language translation
`will be required to be supplied in evety 34 U.S. C. 111 (a) application claiming priority of the non-English
`language provisional application. Notice of Apri/14, 1995, 60 Fed. Reg. 20,195, at 20,209.
`10. Fee
`The filing fee for this provisional application, as set in 37 C.F .R. § 1.16{1<), is $150.00,
`for other than a small entity, and $75.00, for a small entity.
`0 Applicant is a small entity.
`"A verified statement in compliance with existing § 1.27 is required to be filed in each provisional
`NOTE:
`application in which it is desired to pay reduced fees." Notice of April14, 1995, 60 Fed. Reg. 20,195,
`at 20,197.
`11. Small entity statement
`0 The verified statement(s) that this is a filing by a small entity under 37 C.F.R.
`§§ 1.9 and 1.27 is(are) attached.
`12. Fee payment being made at this time
`0 Not enclosed
`0 No filing fee is to be paid at this time. (This and the surcharge required by
`37 C.F.R. § 1.16(Q can be paid subsequently).
`ill Enclosed
`
`Total fee enclosed
`
`$ 150.00
`
`(Cover Sheet For Filing Provisional Application [23-1]-page 4 of 5)
`
`

`
`13. Method of fee payment
`XJ Check in the amount of $. 15 0 • 0 0
`· 0 Charge Account No.
`in the amount of$ ______ _
`A duplicate of this Cover Sheet is attached.
`
`Please charge Account No.
`
`2 3 -0 4 4 2
`
`for any fee deficiency.
`
`Date: ___ _
`
`Tel.: (
`
`Date: & j-'iv ~ l
`
`Reg. No.: 31,3 91
`
`Tel.: ( 203) 261-1234
`
`Signature of submitter
`
`Q
`~R
`\ -p~ ~~Mr-€-
`
`s;:::;;'
`i
`Signature of attorney
`
`Francis J. Maguire
`(type or print name of attorney)
`Ware, Fressola, Van Der Sluys
`& Adolphson LLP
`P.O. Address
`755 Main Street, P.O. Box 224
`Monroe, Connecticut 06468
`
`(Cover Sheet For Rling Provisional Application [23-1]--page 5 of 5)
`
`

`
`- 1 -
`
`MULTI-CARRIER TELECOMMUNICATION SYSTEM WITH POWER
`
`ADAPTATION MEANS
`
`The present invention relates to a telecommunication transmitter for a
`
`multi-carrier transmission system, said transmitter
`
`including coding means
`
`5
`
`coupled between a
`
`transmitter input and a
`
`transmitter output and able to
`
`modulate a plurality of carriers with data received at said transmitter input and to
`
`derive therefrom symbols which are transmitted towards said transmitter output.
`
`A
`
`multi-carrier
`
`transmission
`
`system
`
`including
`
`such
`
`a
`
`telecommunication transmitter is already known in the art and is for instance a
`
`1 0
`
`Digital Subscriber Line [DSLJ Transceiver Unit [TU] as defined in international
`
`standards such as, for instance, the Asymmetrical Digital Subscriber Line [ADSLJ
`
`standard. This standard is the "ANSI T/.413 - American Notional Standard for
`
`Telecommunications - Network and Customer Installation Interfaces - Asymmetric
`
`Digital Subscriber Line (ADSL) Metallic Interface" of the American National
`
`15
`
`Standards Institute [ANSI], New York - 1995. The digital data received at the
`
`input of such a known transmitter is grouped
`
`into frames comprising a
`
`predetermined number of bits and wherefore the coding means generates
`
`corresponding symbols which ore transmitted to a
`
`telecommunication
`
`line
`
`connected to the transmitter output. Since the voltage of each symbol may have
`
`20
`
`different peak values, the signal voltage transmitted on the telecommunication
`
`line may vary within a relatively large range. As a consequence, the power
`
`dissipated in the telecommunication transmitter is relatively high because it has to
`
`support a large value of signal voltage to avoid, or at least minimize, occasional
`
`clipping.
`
`25
`
`An object of the present invention is to provide a telecommunication
`
`transmitter of the above known type but whereof the power dissipation is
`
`dramatically reduced.
`
`According to the invention, this object is achieved due to the fad that
`
`said telecommunication transmitter further includes carrier selection means
`-
`--
`adapted to apply said carriers to said coding means, and data traffic detection
`
`30
`
`means adapted to detect if idle data are received at said transmitter input and, if
`
`Express Mail No. EM537164598US
`
`120 045AN
`
`

`
`- 2 -
`
`idle data are detected, to control said carrier selection means to apply a
`
`predetermined reduced set of said carriers to said coding means.
`
`In this way, when idle data are received at the transmitter input, the
`
`symbols generated by the coding means are merely derived from a few carriers
`
`5
`
`instead of from all the carriers as it is the case when effective data are applied to
`
`the transmitter input. The power on the line is thereby dramatically reduced, as
`
`well as the relatively high power dissipated in the coding means and thus in the
`
`telecommunication transmitter.
`
`Since the symbols, which are generated when idle data are received
`
`l 0
`
`at the transmitter input, contain only a few carriers, the power dissipated in the
`
`transmitter is reduced. In other words, if the number of carriers drops, the
`
`dissipated power is reduced accordingly.
`
`Another characteristic feature of the present invention is that said
`
`predetermined reduced set of carriers comprises only one carrier that is applied
`
`1 5
`
`to said coding means.
`
`For frequency synchronization purposes, the only one remaining
`
`symbol transmitted on the line can be chosen to be derived from a so-called
`
`"pilot tone". The transmission system remains thus efficient in that it allows a fast
`
`restart owing to the fact that the synchronization on the telecommunication line is
`
`20 maintained, while the power dissipated is dramatically reduced with respect to
`
`that of the known system.
`
`In a preferred embodiment,
`
`the present
`
`invention
`
`JS
`
`further
`
`characterized 1n that said telecommunication transmitter further includes data
`
`selection means adapted to apply said data to said coding means, and in that
`
`25
`
`said data traffic detection means is further adapted, if idle data are detected, to
`
`control said data selection means to discard the idle data received at said
`
`transmitter input.
`
`As idle data may, in some circumstances, be dummy data, the latter
`
`could be used by the coding means to moduJote the _few or single carrier(s) from
`
`30 which symbols could then be derived and transmitted on the telecommunication
`
`line. However, owing to the present invention such dummy data would be
`
`120 045AN
`
`

`
`- 3-
`
`discarded and the single earner will remain un-modulated. As a result, the
`
`power dissipation is then minimal.
`
`It should be noted that the switching between symbols derived from
`
`effective data and symbols derived from idle data, and vice-versa, can be fast
`
`5 whereby the power savings can be improved.
`
`Preferably, said telecommunication transmitter operates according to
`
`a predetermined mapping and modulating protocol defined by a digital
`
`subscriber line [DSL] standard such as the Asymmetrical Digital Subscriber Line
`
`[ADSLJ standard, and said symbols derived from said data are Discrete
`
`1 0 Multi-Tone {DMTJ symbols.
`
`It is obvious for a person skilled in the art that the above multi-carrier
`
`transmission technique is not limited to ADSL applications using DMT symbols,
`
`but can for instance also be used in High speed Digital Subscriber Line [HDSLJ
`
`applications, in Very high speed Digital Subscriber Line [VDSLJ applications, in
`
`15
`
`Symmetrical Digital Subscriber Line [SDSL] applications as well as in relation with
`
`Orthogonal Frequency Division Multiplexing [OFDM] and/or Discrete Wavelet
`
`Multi Tone [DWMTJ applications. The latter are also multi-carrier transmission
`
`techniques differing from ADSL in that, for instance for DWMT, the Fourier and
`
`inverse-Fourier transformers used therein are replaced by filterbanks, wavelets
`
`20
`
`transformers and/or Discrete Cosine Transformers [DCTJ.
`
`Also another characteristic feature of the present invention is that said
`
`coding means is adapted to count the number of symbols transmitted towards
`
`said transmitter output and to transmit at least one synchronization symbol after
`
`each group of N symbols, said synchronization symbol being derived from a
`
`25
`
`frame of synchronization signals received at said data selection means, and that
`
`said N symbols and said one synchronization symbol form
`
`together a
`
`super-frame.
`
`In case of idle data, and as already mentioned, the frequency
`
`synchroniznl:ion between the transmitter and a receiver at the other eod of the.
`
`30
`
`telecommunicatiOn line is maintained owing to the presence of the pilot tone. By
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`120 045AN
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`

`
`- 4 -
`
`sending one synchronization symbol for every N symbols,
`
`the framing
`
`synchronization is also maintained between the transmitter and the receiver.
`
`The invention is further also characterized in that said coding means is
`
`adopted to transmit at least one line monitoring super-frame after each grou·p of
`
`5 M super-frames, said line monitoring super-frame including N symbols and at
`
`least one synchronization symbol, in that said M super-frames and said line
`
`monitoring super-frame form together a hyper-frame, and in that said data
`
`traffic detection means is adopted to control said carrier selection means to apply
`
`all the carriers of said plurality to said coding means during the transmission of
`
`10
`
`said line monitoring super-frame.
`
`In the digital subscriber line transmission, the rece1ver measures the
`
`quality of the transmission on the line and informs the transmitter about this
`
`quality. The measurement is performed by means of the line monitor symbols
`
`transmitted in the line monitoring super-frame. If the quality of the transmission
`
`15
`
`becomes to low, the receiver may request the transmitter to go back to the
`
`power-up status even if idle data ore received at the transmitter input.
`
`Still another characteristic feature of the present invention is that said
`
`data traffic detection means is adopted to control said data selection means to
`
`discard idle data received at said transmitter input after idle data has been
`
`20
`
`detected for a predetermined period of time.
`
`In a preferred application, said data received at said transmitter input
`
`ore Asynchronous T ronsfer Mode [ATM] cells.
`
`Also according to the present invention, the power dissipated in the
`
`telecommunication
`
`transmitter con be even more reduced owing to the
`
`25
`
`characteristic feature that said telecommunication transmitter further includes line
`
`driver means coupled between said coding means and said transmitter output
`
`and adapted to amplify the symbols generated by said coding means prior to
`
`transmit them to said transmitter output, said line driver means comprising the
`
`parallel connection of a relatively low '3fficiency line amplifier and a relatively
`
`30
`
`high efficiency line amplifier, that said amplifiers operate in a complementary
`
`way so that only one of said amplifiers is operational at a predetermined time
`
`moment, and that said data traffic detection means is further adapted to control
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`120 045AN
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`

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`- 5 -
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`the operation of said relatively high efficiency line amplifier if idle data are
`
`detected, and to control the operation of said relatively low efficiency line
`
`amplifier else.
`
`When sending only the pilot tone, the line drive means do not need to
`
`5
`
`comprise a class-A or class-AB amplifier that is a high voltage and high
`
`performant line amplifi~r. It may then advantageously be replaced by a lower
`
`voltage and thus also less power consuming line amplifier, i.e. an amplifier with
`
`a smaller idle power dissipation or a smaller supply voltage.
`
`It is to be noted that this last characteristic feature of the present
`
`1 0
`
`invention is preferably, but not necessary, combined with the features mentioned
`
`above. It is thus for instance possible to have a telecommunication transmitter
`
`with line driver means comprising the parallel connection of a low efficiency line
`
`amplifier and a high efficiency line amplifier operating in a complementary way/
`
`but without carrier selection means and possibly data selection means as
`
`1 5 mentioned above.
`
`In a preferred embodiment, if idle data are detected, said one carrier
`
`applied to said relatively high efficiency line amplifier is a sinusoidal wave.
`
`In a variant embodiment, said data traffic detection means is further
`
`adapted, if idle data are detected, to control the quiescent current of said line
`
`20
`
`driver means in order to reduce the power consumption thereof.
`
`Thereby, instead of changing from line amplifier as above, the power
`
`consumption may also be reduced by making the amplifier less linear but more
`
`efficient only for a few number of carriers.
`
`It is to be noted that, in the two last cases, the quality of the symbols
`
`25
`
`derived, e.g., from the pilot tone and transmitted on the telecommunication line
`
`by the high efficiency line drive means remains sufficient to maintain the
`
`frequency synchronization between the transmitter and the receiver.
`
`The present invention is also characterized in that said data traffic
`
`detection means is further adapted to compute the mean traffic of effective data
`
`30
`
`received at said transmitter input over a predetermined period of time, and,
`
`accordingly, to control said carrier selection means to apply a predetermined
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`120 045AN
`
`

`
`- 6 -
`
`reduced set of said carriers to said coding means m function of the computed
`
`mean traffic.
`
`The amount of carriers used by the coding means and their power is
`
`then a function of the data traffic. By using only the number of carriers that are
`
`5
`
`necessary to transmit the effective data, and each with less power, i.e. modulated
`
`with less bits of the data, instead of always using qll the carriers when the actual
`
`data are reduced, the power consumption of the transmitter is reduced in
`
`function of the data traffic. This switching between high and low capacity could
`
`be done in a similar fashion as switching between high capacity and idle.
`
`10
`
`The above and other objects and features of the invention will become
`
`more apparent and the invention itself will be best understood by referring to the
`
`following description of an embodiment taken
`
`in . conjunction with
`
`the
`
`accompanying drawings wherein:
`
`FIG. 1 represents a telecommunication transmitter TU according to the
`
`15
`
`invention;
`
`FIG. 2 shows, at different time scales, a super-frame SF and a
`
`hyper-frame HF of signals used in the transmitter of the FIG. 1 ; and
`
`FIG. 3 represents a possible implementation of the line driver circuit
`
`LDC included in the telecommunication transmitter TU ~f FIG. 1.
`
`20
`
`The telecommunication transmitter TU shown in FIG. 1 is of the type
`
`"ADSL Transceiver Unit - Central office side" [ATU-C} used in multi-carrier
`
`transmission system as for instance defined in the above mentioned Asymmetrical
`
`Digital Subscriber Line [ADSL] standard. Several of such transmitters are
`
`mounted
`
`in a
`
`rack which
`
`ts subjected
`
`to maxtmum power dissipation
`
`25
`
`requirements. The transmitter TU has an input IN whereat digital data, e.g.
`
`Asynchronous Transfer Mode [ATMJ cells, are applied, and an output OUT where
`
`so-called "symbols" are provided. These symbols are the result of, amongst
`
`other, mapping and modulating operations performed by a data handling
`
`circuit, generally referred to as DHC, on the data received at the input IN. The
`
`30
`
`transmitter TU further also includes a line driver circuit LDC coupling the data
`
`handling circuit DHC to the output OUT via a terminal Ll and amplifying the
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`120 045AN
`
`

`
`- 7 -
`
`symbols prior to transmit them on a telecommunication line connected to the
`
`output OUT. The telecommunication line is a copper twisted pair of wires
`
`whereof the other end is connected to a remote ADSL transceiver (not shown).
`
`It is to be noted that in FIG: 1, the schematic representation of the
`
`5
`
`ADSL transmitter TU has been largely simplified in order to show only the
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`elements which are essential to understand the scope of the invention.
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`The data received at the input IN is applied to an input DATA of a
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`data selector DS forming part of the data handling circuit DHC. The data selector
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`DS has a second input SYNC at which synchronization signals are supplied, as
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`10 will be explained later. An output of DS is connected to an input of a mappmg
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`and modulating circuit, hereafter merely called coding circuit MMC, of which
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`another input is connected to an output of a carrier selector CS. An output of the
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`coding circuit MMC is connected to a terminal Ll further connected to an input of
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`the line driver circuit LDC whereof an output is connected to the transmitter
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`15
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`output OUT.
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`Both MMC and CS form part of the data handling circuit DHC.
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`Several carriers Cl, ... , Cp, .. , Cn, of which the frequencies are spread over the
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`frequency spectrum of the Digital Subscriber Line [DSL] system and that may be
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`pre-selected amongst a full set of carriers for their good transmission qualities for
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`20
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`the particular line connected to the transmitter TU, are applied to like-named
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`input terminals of the carrier selector CS. These carriers are sinusoidal waves and
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`one of them, referred to as Cp, is the so-called "pilot tone" that insures the
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`frequency synchronization between the present transmitter and a
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`rece1ver
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`included in the ADSL transceiver at the other end of the telecommunication line.
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`25
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`The data selector DS and the carrier selector CS are controlled by a
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`data traffic detection circuit DDC via a terminal LX connected to control terminals
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`DX and CX of DS and CS respectively. The incoming data of the transmitter TU is
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`received in DOC via an input thereof that is connected to the transmitter input IN.
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`The d<;:~ia traffic detection circuit DDC is adapted to detect the type of digital data:
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`30
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`idle or effective, as well as the mean traffic of this data, received at the input IN.
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`- 8-
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`According to the result of this detection, DDC controls the selectors DS and CS as
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`will be explained below.
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`If effective data are received at the transmitter input IN, and thus also
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`at the data input DATA of the data selector DS, the latter circuit groups the bits of
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`5
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`the data into "frames11
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`• These frames are then transferred to the coding circuit
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`MMC that maps them to the carriers Cl-Cn received via the carrier selector CS.
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`MMC further modulates these carriers Cl-Cn in function of the results of the
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`mapping thereby generating Discrete Multi-Tone [DMT] symbols. that are
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`transferred to the line driver circuit LDC. It is to be noted that the pilot tone Cp is
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`10
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`preferably not modulated
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`to ensure
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`the above mentioned
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`frequency
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`synchronization. The purpose of the line driver circuit LDC is to amplify the
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`symbols prior to transmit them on the telecommunication line, its operation will
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`be described in more detail later.
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`For every N=68 DMT symbols transmitted on the line, at least one
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`15
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`synchronization symbol is sent. To this end, at the occurrence of the 69th symbol,
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`the data selector DS selects its second input SYNC to get the synchronization
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`signals instead of the data from its first input DATA. As for the data, the
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`synchronization signals are also grouped into frames by the data selector DS.
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`The synchronization symbol derived from such a frame is used for performing
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`20
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`framing synchronization between the transmitter TU and the receiver at the other
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`end of the line. A set of N=68 DMT symbols (numbered from 0 to 67) and one
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`synchronization
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`symbol SS
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`(numbered 68)
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`form
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`together
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`a
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`so-called
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`"super-frame// SF as shown in FIG. 2.
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`Furthermore, after having generated M, e.g. M=256, of the above
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`25
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`super-frames,
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`the coding circuit MMC generates at
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`least one so-called
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`"line-monitoring super-frame" MSF. This special super-frame MSF contains line
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`monitoring information used by the receiver to measure the quality of the
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`transmission on the line. A set of M super-frames and one or more line
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`monitoring super-frame(sJ MSF fQrm together a so-called 11hyper-frame". An
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`30
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`example of such a hyper frame HF with M=256 super-frames SF (numbered
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`from 0 to 255) and one line monitoring super-frame MSF (numbered 0) is shown
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`- 9-
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`1n FIG. 2 at a time period t' that is larger than the time period t showing the
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`super-frame SF in the same figure. A line monitoring super-frame MSF includes
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`N=68 line monitoring symbols and the synchronization symbol SS. Each line
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`monitoring symbol being generated by applying all the carriers Cl to Cn to the
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`5
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`coding circuit MMC.
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`The operation of the data handling circuit DHC and more particularly
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`that of the coding circuit MMC will not be described in more detail here since all
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`the details of the functioning of these circuits may be found in the above
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`mentioned Asymmetrical Digital Subscriber Line [ADSL] standard.
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`10
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`The power dissipated in the transmitter TU
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`if effective data are
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`transmitted is of about 3 Watt for 1 00 milliWatt effectively transmitted on the
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`telecommunication line. This low efficiency is due to several ADSL requirements
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`such as the signal quality requirement. Hereafter will be explained how this
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`power dissipation will be reduced in function of the traffic on the line.
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`15
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`If idle data are received at the transmitter input IN, it is detected by
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`the data traffic detection circuit DDC which then controls, via the terminal CX, the
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`carrier selector CS to allow only a few of the carriers Cl-Cn to be transferred to
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`the coding circuit MMC. By generating symbols that are derived from a reduced
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`number of carriers, the power dissipated in the transmitter TU is dramatically
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`20
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`reduced. If the set of selected carriers is reduced to one, the pilot tone Cp is
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`preferably chosen, with respect to the other carriers Cl-Cn, as the single
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`remaining carrier because it allows to maintain the frequency synchronization
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`between the transmitter and the receiver.
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`In some cases, such as for instance for the transmission of ATM cells,
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`25
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`the idle data are in fact dummy data that could be grouped in frames by the
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`data selector DS and then be transferred to the coding circuit MMC. To avoid the
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`generation of symbols derived from such dummy data, the data traffic detection
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`circuit DDC also controls, via the terminal DX, the data selector DS to discard any
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`idle data received at the input DATA. As a result, no ~ata ar~Jhen applied to the
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`30 - coding circuit MMC.
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`In other words, if idle data are received in the transmitter TU and
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`detected by the data traffic detection circuit DOC, the latter controls the carrier
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`selector CS and the data selector OS in such a way that the coding circuit MMC
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`generates for instance un-modulated symbols, generally- called "pilot symbols",
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`5
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`instead of the above discrete multi-tone OMT symbols. The
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`frequenc