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WO1998032267A1 - Recepteur mrof utilisant des signaux pilotes - Google Patents

Recepteur mrof utilisant des signaux pilotes Download PDF

Info

Publication number
WO1998032267A1
WO1998032267A1 PCT/GB1997/003549 GB9703549W WO9832267A1 WO 1998032267 A1 WO1998032267 A1 WO 1998032267A1 GB 9703549 W GB9703549 W GB 9703549W WO 9832267 A1 WO9832267 A1 WO 9832267A1
Authority
WO
WIPO (PCT)
Prior art keywords
carriers
values
pilot
store
scattered
Prior art date
Application number
PCT/GB1997/003549
Other languages
English (en)
Inventor
Roger Paul Dealtry
Adrian Charles Turner
Original Assignee
Nds Limited
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 Nds Limited filed Critical Nds Limited
Priority to AU53333/98A priority Critical patent/AU5333398A/en
Publication of WO1998032267A1 publication Critical patent/WO1998032267A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2657—Carrier synchronisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2668—Details of algorithms
    • H04L27/2673—Details of algorithms characterised by synchronisation parameters
    • H04L27/2675—Pilot or known symbols

Definitions

  • the present invention relates to a method and apparatus for receiving frequency division multiplex signals and is particularly adapted to receiving orthogonal frequency division multiplex (OFDM) signals and discrete multitone (DMT) signals.
  • OFDM signals include data carriers and reference carriers.
  • the reference carriers are in the form of a sequence of pilot signals which are distributed in frequency and in time and are transmitted with a pattern of values known to the receiver.
  • the pilot signals are used to calculate the data values between them and the data carriers are modified by reference to the pilot signals to compensate for channel distortions. This process is known as channel equalisation.
  • the present invention seeks to provide an improved method and apparatus to receive a frequency division multiplex signal.
  • apparatus to receive a frequency division multiplex signal which includes a sequence of symbols each of which has data carriers and reference carriers, the apparatus comprising an extractor to extract reference carriers from the multiplex signal, an interpolator to interpolate values interspersed between the extracted reference carriers, error indicating means to derive an indication from the reference carriers of a common phase error for each symbol and means to modify the interpolated values in response to the common phase error indication.
  • a method of receiving a frequency division multiplex signal which includes a sequence of symbols each of which has data carriers and reference carriers, the method comprising extracting reference carriers from the multiplex signal, interpolating values interspersed between the extracted reference carriers, deriving from the reference carriers an indication of a common phase error for each symbol and modifying the interpolated values in response to the common phase error indication.
  • FIG. 1 shows a block diagram of an OFDM receiver according to the present invention
  • Figure 2 is one example of the pattern of data carriers and pilot signals in an OFDM signal to be received by the receiver of Figure 1 , and
  • Figure 3 is block circuit diagram showing a time interpolator section of the receiver of Figure 1 ,
  • the OFDM signal includes a succession of symbols which are indicated in Figure 2.
  • Each symbol includes a set of frequency spaced data carriers indicated as x in Figure 2 together with scattered pilots or reference carrier signals, indicated as O, which are distributed amongst the data carriers.
  • the symbols each have continuous pilots or reference carrier signals O one of which is shown at the right hand margin of Figure 2.
  • the scattered pilots are distributed throughout the data carriers in a predetermined pattern and have values which are known at the receiver.
  • the receiver has a circuit 11 to extract the data to be passed on to a block 14 at which the data carriers are modified to compensate for distortions in the transmission channel.
  • the pilot or reference signals are also extracted at the circuit 11 and passed to a block 13.
  • the block 13 uses the pilots to model the transmission channel and supplies signals to the block 14 which equalises the data received from the circuit 11.
  • the transmission channel introduces distortions which change across the carriers and with time.
  • a problem is introduced by the receiver itself which adds a small phase error component which is common to all the carriers of one OFDM symbol and is known as the common phase error.
  • the first symbol is formed by the carriers and pilots indicated at the top line and all subject to the common phase error ⁇
  • the first carrier is shown to have a channel phase shift ⁇ ., and a common phase error ⁇ .
  • the continuous pilot shown at the right margin of Figure 2 has a channel phase shift of oc, and a common phase error of ⁇ .
  • the second symbol in Figure 2 has a common phase error of ⁇ 2 associated with all the carriers of the second symbol.
  • the continuous pilot of the second symbol has a channel phase shift of ⁇ 2 and a common phase error of ⁇ 2 .
  • Succeeding symbols n have respective channel common phase errors of ⁇ n as indicated in Figure 2 for the first seven symbols in the sequence of symbols.
  • Each continuous pilot signal has a corresponding channel phase shift ⁇ n and common phase error ⁇ n as shown for the first seven symbols.
  • the scattered pilots are arranged in a pattern throughout the sequence of symbols such that the pattern repeats once every four symbols. This means that a pilot value has to be interpolated in time for those positions which do not have a transmitted pilot value.
  • Each time interpolated pilot value is derived by reference to the repeating pattern of transmitted pilot values and consequently, although the data carriers of each symbol have the common phase error associated with that symbol, the interpolated pilot values will have a phase error which is made up of a combination of the common phase errors of other symbols. It is advantageous to maintain the correct common phase component in the interpolated pilot values.
  • V 4 describes the actual value of a carrier in symbol 4
  • V' 4 describes the estimated value of a carrier in symbol 4
  • V 4 ( ⁇ 2 + ⁇ 6 ) / 2 + ( ⁇ 2 + ⁇ 6 ) /2 (1 )
  • V 4 ⁇ 4 + ⁇ 4 (2)
  • K' 4 ( ⁇ 2 + ⁇ 6 )/2 + ( ⁇ 2 + ⁇ ⁇ )/2 (4)
  • the carrier under consideration in this case is a continuous pilot
  • absolute value comprising the channel phase shift and common phase
  • the reference signals are supplied to a pilot signal separator 15.
  • the separator 15 supplies the scattered pilots to a scattered pilot store 16 which stores the two most recent values for the transmitted pilots.
  • a time interpolator 17 performs a linear interpolation between the values stored in the pilot store 16 to provide a time interpolated value for each possible pilot carrier.
  • a continuous pilot store 18 and an interpolation error accumulator circuit 19 are used to provide error signals to correct the common phase components in the time interpolated pilot signals produced by the time interpolator 17.
  • the store 18 receives continuous pilot signals which have been extracted by the pilot signal separator 15 and is effective to store the continuous pilot signals for the last five symbols.
  • the error accumulation circuit performs a sequence of comparisons between the continuous pilots in the store 18 and the interpolated estimates produced for each symbol by the time interpolator 17 operating on the continual pilots. For the purpose of comparison, the time interpolator supplies each time interpolation as an input to the error accumulation circuit 19.
  • 3 error terms E n+1 , E n+2 and E n+3 are calculated from the continuous pilot signals to derive an indication of error which is forwarded from the accumulator 19 to a common phase error restoration circuit 20.
  • the circuit 20 restores the common phase error in respect of the interpolated pilots which are transmitted to the restoration circuit from the time interpolator 17 by way of a delay circuit 21 which imposes a delay to the pilots of one symbol.
  • the accuracy of the error signal passed to the restoration circuit 20 is improved by averaging each of the 3 error signals across the symbol. Frequency interpolation of the pilots can now be carried out across the symbol maintaining the common phase error which will be equalised out along with the channel distortions. This adds little complexity and prevents errors propagating in time and subsequently in frequency.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)
  • Circuits Of Receivers In General (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)

Abstract

La présente invention a trait d'une manière générale à la réception des signaux à multiplexage par répartition de la fréquence, et plus précisement, l'invention concerne un procédé et un dispositif de réception des signaux à multiplexage par répartition orthogonale de la fréquence (MROF). Ces signaux MROF contiennent à la fois des signaux donnée et des signaux référence (également connus comme signaux pilotes). Ces signaux pilotes sont utilisés pour corriger par interpolation les distorsions canal et le déphasage accidentel, communs à tous les signaux, affectant les signaux donnée et introduits par le récepteur lui-même.
PCT/GB1997/003549 1997-01-17 1997-12-24 Recepteur mrof utilisant des signaux pilotes WO1998032267A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU53333/98A AU5333398A (en) 1997-01-17 1997-12-24 Ofdm receiver using pilot carriers

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9700947.6 1997-01-17
GBGB9700947.6A GB9700947D0 (en) 1997-01-17 1997-01-17 Method and apparatus for receiving frequency division multiplex signals

Publications (1)

Publication Number Publication Date
WO1998032267A1 true WO1998032267A1 (fr) 1998-07-23

Family

ID=10806160

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1997/003549 WO1998032267A1 (fr) 1997-01-17 1997-12-24 Recepteur mrof utilisant des signaux pilotes

Country Status (3)

Country Link
AU (1) AU5333398A (fr)
GB (1) GB9700947D0 (fr)
WO (1) WO1998032267A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1039715A1 (fr) * 1999-03-25 2000-09-27 Kabushiki Kaisha Toshiba Répéteur d'un signal de transmission MDFO
FR2811663A1 (fr) 2000-07-13 2002-01-18 Commenplus Materiau luminescent de ragreage et procede de mise en place d'un tel materiau
WO2007120326A3 (fr) * 2005-12-20 2008-02-21 Qualcomm Inc Procédés et systèmes pour apporter une localisation améliorée de position dans des communications sans fil
WO2008089595A1 (fr) * 2007-01-19 2008-07-31 Thomson Licensing Procédé d'interpolation de domaine temporel et dispositif d'estimation de canal
US8068567B2 (en) 2004-05-04 2011-11-29 Infineon Technologies Ag Phase and frequency control of an ODFM receiver by means of pilot phase-value estimation
CN102857466A (zh) * 2012-08-06 2013-01-02 北京海尔集成电路设计有限公司 正交频分复用系统公共相差补偿方法及装置

Citations (10)

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Publication number Priority date Publication date Assignee Title
WO1991020137A1 (fr) * 1990-06-12 1991-12-26 Motorola, Inc. Signal de communication comportant un composant pilote de domaine temporel
US5274629A (en) * 1990-02-06 1993-12-28 Etat Francais and Telediffusion de France SA Method for the broadcasting of digital data, notably for radio broadcasting at high bit rate towards mobile receivers, with time-frequency interlacing and coherent demodulation
DE4310031A1 (de) * 1993-03-27 1994-09-29 Grundig Emv Verfahren zur Korrektur von Phase und Amplitude eines breitbandigen Empfangssignals mit Hilfe von Referenzsignalen
JPH06284028A (ja) * 1992-06-23 1994-10-07 Nec Corp フェーディングひずみ補償方式
WO1995020848A1 (fr) * 1994-01-28 1995-08-03 Philips Electronics N.V. Systeme de transmission numerique
JPH07202973A (ja) * 1993-12-30 1995-08-04 Matsushita Electric Ind Co Ltd フェージング歪補償装置
JPH08149176A (ja) * 1994-11-18 1996-06-07 Hitachi Denshi Ltd 復調器
EP0736986A1 (fr) * 1995-03-31 1996-10-09 Sony Corporation Appareil de transmission, appareil de réception et méthode associée, qui utilisent des données de référence, insérées dans le signal de transmission, pour estimer la qualité du canal de transmission
EP0762703A1 (fr) * 1995-08-21 1997-03-12 France Telecom Démodulation d'un signal multiporteur diminuant une distorsion blanche en fréquence
EP0762702A1 (fr) * 1995-08-21 1997-03-12 France Telecom Procédé et dispositif de démodulation d'un signal multiporteur tenant compte d'une estimation de la réponse du canal de transmission et d'une estimation d'une distorsion blanche en fréquence

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5274629A (en) * 1990-02-06 1993-12-28 Etat Francais and Telediffusion de France SA Method for the broadcasting of digital data, notably for radio broadcasting at high bit rate towards mobile receivers, with time-frequency interlacing and coherent demodulation
WO1991020137A1 (fr) * 1990-06-12 1991-12-26 Motorola, Inc. Signal de communication comportant un composant pilote de domaine temporel
JPH06284028A (ja) * 1992-06-23 1994-10-07 Nec Corp フェーディングひずみ補償方式
DE4310031A1 (de) * 1993-03-27 1994-09-29 Grundig Emv Verfahren zur Korrektur von Phase und Amplitude eines breitbandigen Empfangssignals mit Hilfe von Referenzsignalen
JPH07202973A (ja) * 1993-12-30 1995-08-04 Matsushita Electric Ind Co Ltd フェージング歪補償装置
WO1995020848A1 (fr) * 1994-01-28 1995-08-03 Philips Electronics N.V. Systeme de transmission numerique
JPH08149176A (ja) * 1994-11-18 1996-06-07 Hitachi Denshi Ltd 復調器
EP0736986A1 (fr) * 1995-03-31 1996-10-09 Sony Corporation Appareil de transmission, appareil de réception et méthode associée, qui utilisent des données de référence, insérées dans le signal de transmission, pour estimer la qualité du canal de transmission
EP0762703A1 (fr) * 1995-08-21 1997-03-12 France Telecom Démodulation d'un signal multiporteur diminuant une distorsion blanche en fréquence
EP0762702A1 (fr) * 1995-08-21 1997-03-12 France Telecom Procédé et dispositif de démodulation d'un signal multiporteur tenant compte d'une estimation de la réponse du canal de transmission et d'une estimation d'une distorsion blanche en fréquence

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MUSCHALLIK C: "INFLUENCE OF RF OSCILLATORS ON AN OFDM SIGNAL", IEEE TRANSACTIONS ON CONSUMER ELECTRONICS, vol. 41, no. 3, August 1995 (1995-08-01), NEW YORK, US, pages 592 - 603, XP000539512 *
PATENT ABSTRACTS OF JAPAN vol. 095, no. 001 28 February 1995 (1995-02-28) *
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RINNE J: "AN EQUALIZATION METHOD USING PRELIMINARY DECISIONS FOR ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING SYSTEMS IN CHANNELS WITH FREQUENCY SELECTIVE FADING", 1996 IEEE 46TH. VEHICULAR TECHNOLOGY CONFERENCE, MOBILE TECHNOLOGY FOR THE HUMAN RACE, ATLANTA, APR. 28 - MAY 1, 1996, vol. 3, 28 April 1996 (1996-04-28), NEW YORK, US, pages 1579 - 1583, XP000595797 *

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1039715A1 (fr) * 1999-03-25 2000-09-27 Kabushiki Kaisha Toshiba Répéteur d'un signal de transmission MDFO
FR2811663A1 (fr) 2000-07-13 2002-01-18 Commenplus Materiau luminescent de ragreage et procede de mise en place d'un tel materiau
US8068567B2 (en) 2004-05-04 2011-11-29 Infineon Technologies Ag Phase and frequency control of an ODFM receiver by means of pilot phase-value estimation
EP3306338A1 (fr) * 2005-12-20 2018-04-11 Qualcomm Incorporated Localisation de position améliorée dans des communications sans fil
WO2007120326A3 (fr) * 2005-12-20 2008-02-21 Qualcomm Inc Procédés et systèmes pour apporter une localisation améliorée de position dans des communications sans fil
US7876265B2 (en) 2005-12-20 2011-01-25 Qualcomm Incorporated Methods and systems for providing enhanced position location in wireless communications
US7893873B2 (en) 2005-12-20 2011-02-22 Qualcomm Incorporated Methods and systems for providing enhanced position location in wireless communications
US10694517B2 (en) 2005-12-20 2020-06-23 Qualcomm Incorporated Methods and systems for providing enhanced position location in wireless communications
US8773308B2 (en) 2005-12-20 2014-07-08 Qualcomm Incorporated Methods and systems for providing enhanced position location in wireless communications
US9955476B2 (en) 2005-12-20 2018-04-24 Qualcomm Incorporated Methods and systems for providing enhanced position location in wireless communications
WO2008089595A1 (fr) * 2007-01-19 2008-07-31 Thomson Licensing Procédé d'interpolation de domaine temporel et dispositif d'estimation de canal
CN102857466B (zh) * 2012-08-06 2015-02-25 北京海尔集成电路设计有限公司 正交频分复用系统公共相差补偿方法及装置
CN102857466A (zh) * 2012-08-06 2013-01-02 北京海尔集成电路设计有限公司 正交频分复用系统公共相差补偿方法及装置

Also Published As

Publication number Publication date
GB9700947D0 (en) 1997-03-05
AU5333398A (en) 1998-08-07

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