WO2005096581A1 - Demodulateur cofdm a positionnement optimal de fenetre d'analyse fft - Google Patents
Demodulateur cofdm a positionnement optimal de fenetre d'analyse fft Download PDFInfo
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- WO2005096581A1 WO2005096581A1 PCT/FR2005/050199 FR2005050199W WO2005096581A1 WO 2005096581 A1 WO2005096581 A1 WO 2005096581A1 FR 2005050199 W FR2005050199 W FR 2005050199W WO 2005096581 A1 WO2005096581 A1 WO 2005096581A1
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- filtering function
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- impulse response
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Classifications
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- 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
- H04L27/2662—Symbol synchronisation
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- 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
- H04L27/2662—Symbol synchronisation
- H04L27/2665—Fine synchronisation, e.g. by positioning the FFT window
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/0202—Channel estimation
- H04L25/022—Channel estimation of frequency response
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2602—Signal structure
- H04L27/2605—Symbol extensions, e.g. Zero Tail, Unique Word [UW]
- H04L27/2607—Cyclic extensions
Definitions
- the present invention relates to a so-called COFDM demodulator ("Coded Orthogonal Frequency Division Multiplex" or multiplexing by coded orthogonal frequency division).
- Figure 1 is intended to illustrate the principle of a COFDM modulation.
- Data packets to be transmitted are put in the form of N complex coefficients associated with N respective frequencies (or carriers).
- the number N of the frequencies is equal, for example, to 1705 for the so-called "2K” mode and to 6817 for the so-called "8K” mode, in digital television broadcasting.
- Each complex coefficient corresponds to a vector which is illustrated in FIG. 1 as starting from a frequency axis at a point indicating the frequency associated with the coefficient.
- IFFT inverse fast Fourier transform
- Tu is the duration of emission of a symbol and is called useful life.
- the useful life is around 224 ⁇ s in 2K mode and 896 ⁇ s in 8K mode, for a bandwidth of 8MHz.
- FFT fast Fourier transform
- some vectors PI, P2, P3 ... regularly distributed have a known constant value.
- pilots are called pilots. They serve to reflect the distortions undergone by the transmitted signal and by the information they give on the response of the channel, they make it possible to correct the unknown vectors located between the pilots.
- FIG. 2 illustrates a transmission of several successive symbols Sn-1, Sn ... As shown, each of these symbols is preceded by a guard interval Tgn-1, Tgn which is a copy of part of the end of the corresponding symbol.
- Guard intervals are often defined by a fraction of the useful life Tu. Typical values of the guard interval are Tu / 32, Tu / 16, Tu / 8 or Tu / 4. Guard intervals are used to avoid inter-symbol modulation distortions caused by an echo of the transmission.
- FIG. 2 also represents an echo SEn-1, TgEn-1 ... of the transmitted signal. This echo is delayed with respect to the main signal by a duration shorter than that of a guard interval Tg.
- Each symbol S is normally analyzed by the receiver's FFT circuit in a window W, or FFT analysis window, likewise length as the symbol. If there was no guard interval, an analysis window W coinciding with a symbol of the main signal would straddle two symbols of the echo signal. This would cause an error which is difficult to correct in the computation of the FFT Fourier transform.
- the guard interval Tg provided that it is greater than the delay or the advance of the echo, offers a margin of adjustment of the analysis window W so that it coincides only with portions belonging to the same symbol, both in the main signal and in the echo. The fact that an analysis window straddles a symbol and its guard interval introduces a phase shift which is corrected using the aforementioned pilots.
- the symbol Sn-1 must be analyzed in a Wn-1 window.
- of duration Tu can be positioned indifferently in the window delimited by the instants ta and tb, the instant ta corresponding to the start of the guard interval of the echo TgEn-1, and the instant tb corresponding to the end of the symbol Sn-1.
- the symbol Sn must be analyzed in a window Wn of duration Tu which can be positioned indifferently in the window delimited by the instants te and td, the instant corresponding to you at the start of the guard interval of the echo TgEn, and the instant td corresponding to the end of the symbol Sn.
- FIG. 3 schematically represents the place of pilots in the symbols.
- each line represents a symbol and each box represents the position of a carrier.
- the carriers are defined as going from a position 0 to a Kmax position, Kmax being equal to 1704 in 2K mode and 6816 in 8K mode. In fact, only part of the possible frequencies is used, in particular due to the risk of losses at the edge of the channel.
- pilots There are two types of pilots. On the one hand, there are, in each symbol, continuous pilots Pc. Continuous pilots correspond to particular frequencies distributed in the channel. In the ETSI standard mentioned above, there are 45 in 2K mode and 177 in 8K mode.
- the complex, temporal received signal after having been put into baseband , is supplied to a fast Fourier transform module providing the symbol in the frequency domain. Pilots are removed from this symbol.
- the sampled pilots allow the estimation of the frequency response of the channel which, after having undergone an inverse Fourier transform, provides the estimation of the impulse response of the channel.
- the impulse response estimation of the channel is used to finely position the analysis window W.
- the pilots provide only an incomplete description of the channel. Indeed, taking into account several successive symbols (at least 4) makes it possible to have an image of the channel only every three points. It follows that the estimate of the impulse response of the channel obtained from the pilots has a periodization of period equal to the useful life Tu divided by three.
- Figure 4A shows an example of curve 1
- FIG. 4B represents the module estimation of the impulse response of the channel obtained from the points of the module estimation of the frequency response represented by the black disks in FIG. 4A.
- the estimation in module of the impulse response is schematically represented by a periodic series of pulses 4 whose period is equal to the useful duration Tu divided by 3. For each period, an impulse corresponds to the main path taken by the signal and the other impulses correspond to echoes.
- FIG. 5 schematically illustrates the steps of a conventional method for positioning the analysis window of the FFT circuit from the module estimation of the impulse response.
- the method comprises the following steps: searching, over a period of the estimation in module of the impulse response, the impulse 7 of maximum amplitude which corresponds to the main path; move a window FE, the width of which corresponds to the guard interval Tg, relative to the main path 7 from an initial position 8 (shown in dotted lines) to a final position 9 (shown in continuous lines) and determine, for each position of the window FE, the "energy” of the estimation in modulus of the impulse response in the window FE ' , the "energy” possibly corresponding to the sum of the amplitudes of the pulses present in the window FE; and refine the positioning of the analysis window W from the position of the window FE corresponding to "maximum energy".
- the position of the window FE corresponding to a maximum energy is generally used moreover to determine the estimate of the frequency response for the carriers other than continuous or distributed pilots, represented by white disks 6 in FIG. 4A.
- an interpolation filter is generally applied to the estimation of the impulse response, the positioning of which is refined as a function of the maximum energy position of the window FE.
- Such methods for refining the positioning of the FFT analysis window and the positioning of the interpolation filter are implemented on the reference demodulator STV0360 marketed by the applicant.
- the width of the window FE is equal to the guard interval Tg. This means that all the echoes outside the guard interval are not taken into account. account to refine the positioning of the FFT analysis window.
- An object of the invention is to provide an optimal positioning method for the FFT analysis window for a COFDM demodulator allowing echoes to be taken into account outside the guard interval.
- the present invention provides a method for COFDM demodulation of a signal received from a transmission channel, comprising the steps consisting in carrying out the fast Fourier transform of the signal received in a window corresponding to a symbol, each symbol comprising several carriers modulated in phase and / or in amplitude, some of which are pilots, and being attached to a guard interval reproducing part of the symbol; providing a set of estimated values of the impulse response in module from the pilots; determining coefficients, each coefficient being obtained from the product of said set and from a filtering function for a determined relative position of the filtering function with respect to said set; determining the maximum coefficient and the corresponding relative position; and positioning said window as a function of said relative position corresponding to the maximum coefficient, the filtering function comprising a central part of constant amplitude and of duration equal to the duration of the guard interval, surrounded by non-decreasing flanks.
- the step consisting in supplying the set of estimated values of the impulse response in module comprises a step of supplying a set of estimated values of the frequency response of the transmission channel from pilots and a step of transforming said set of estimated values of the frequency response by inverse fast Fourier transform.
- the coefficient is determined from the sum of the products of the estimated values of the set of estimated values of the impulse response in module and of the filtering function.
- the set of estimated values of the impulse response in module is periodic, the filtering function having a total width less than the period of the set of estimated values of the impulse response in module .
- the filtering function is a step function.
- each flank comprises at least a first and a second adjacent rungs each having a non-zero amplitude and strictly less than the amplitude of the central portion, the second rung being adjacent to the central portion , double the amplitude of the second rung being greater than the sum of the amplitude of the central portion and the amplitude of the first rung.
- the duration of the second step is less than the duration of the first step.
- the filtering function is symmetrical.
- the present invention also provides a COFDM demodulator intended to receive a signal received from a transmission channel, comprising a fast Fourier transform circuit of the signal received in a window corresponding to a symbol, each symbol comprising several carriers modulated in phase and / or in amplitude, some of which are pilots, and being attached to a guard interval reproducing part of the symbol; a circuit for supplying a set of estimated values of the impulse response in module of the transmission channel from the pilots; a circuit for determining coefficients, each coefficient being obtained from the product of said set and from a filtering function for a determined relative position of the filtering function with respect to said set; a circuit for determining the maximum coefficient and the corresponding relative position; and a circuit for positioning said window as a function of said relative position corresponding to the maximum coefficient, in which the filtering function used by the circuit for determining the coefficients comprises a central part of constant amplitude and of duration equal to the duration of the guard interval, surrounded by non-zero decreasing flanks.
- FIG. 1 represents carriers modulated in phase and in amplitude in a COFDM transmission system
- FIG. 2 represents signals received by a COFDM demodulator and FFT analysis windows for the signals
- FIG. 3 previously described, schematically represents the position of pilots in symbols
- FIGS. 4A and 4B previously described, schematically represent examples of the module estimates of the frequency response and of the impulse response of the transmission channel
- FIG. 5 previously described, illustrates an example of a conventional method for positioning the FFT analysis window
- FIG. 1 represents carriers modulated in phase and in amplitude in a COFDM transmission system
- FIG. 2 previously described, represents signals received by a COFDM demodulator and FFT analysis windows for the signals
- FIG. 3, previously described schematically represents the position of pilots in symbols
- FIGS. 4A and 4B previously described, schematically represent examples of the module estimates of the frequency response and of the impulse response of the transmission channel
- FIG. 5 previously described, illustrates an example of a conventional method for positioning the FFT analysis window
- FIG. 6 represents an exemplary embodiment of a demodulator according to the present invention
- FIG. 7 represents an exemplary embodiment of a filtering function implemented by the method according to the invention for positioning the FFT analysis window
- FIGS. 8 and 9 illustrate steps of the method according to the invention for positioning the FFT analysis window
- FIGS. 10A, 10B to 13A, 13B illustrate certain advantages of the method according to the invention for positioning the FFT analysis window.
- FIG. 6 represents an example of a COFDM demodulator according to the present invention.
- the received signal includes continuous pilots, distributed pilots, and data carriers.
- an input E of the demodulator receives an IF signal of intermediate frequency allowing sampling, for example 36 MHz.
- the IF signal corresponds to the signal received after various frequency changes or transpositions.
- the input E is coupled to an analog-digital converter 10 (ADC) which digitizes the input signal IF.
- ADC analog-digital converter
- the analog-digital converter 10 drives a frequency change module 12.
- the module 12 provides a signal substantially in baseband, the spectrum of the signal at the output of the module 12 being centered on a frequency substantially equal to zero.
- the module 12 is coupled to a module 14 making it possible, on the one hand, to fine-tune the central frequency of the signal spectrum and, on the other hand, to provide time samples at times suitable for further processing.
- the signal spectrum is centered on a frequency equal to 0 and the number and the temporal position of the samples are adapted to the transformation by Fourier transform which takes place in the following module.
- the module 14 is controlled by links 15 and 15 ′ connecting the module 14 to a module 16 for processing the continuous and distributed pilots.
- the output of the module 14 drives a fast Fourier transform (FFT) module 20 which supplies the frequencies corresponding to a symbol.
- the module 20 is controlled by a module 22 which provides, via a link 24, a signal for adjusting the analysis window of the Fourier transform.
- the output of module 20 is coupled to module 16 which extracts and processes continuous and distributed pilots.
- the module 16 provides on the links 15 and 15 'the signals intended to correct the center frequency of the spectrum and the sampling frequency of the signal.
- the output of the module 20 drives a module 30 in which the signal is corrected using an estimate of the frequency response of the channel.
- the estimation of the frequency response of the channel is carried out in module 16 using the pilots.
- This estimate is provided by the module 16 on a link 35, a branch 35a of which is coupled to the module 30.
- the signal comprises the carriers carrying the data.
- the estimation of the frequency response of the channel, supplied by the module 16, feeds, via the link 35 and a branch 35b of the link 35, a module 36 of inverse Fourier transform (IFFT), for determine the impulse response of the channel.
- IFFT inverse Fourier transform
- the module 36 provides the impulse response of the channel to the module 22, to dynamically adjust the positioning of the FFT analysis window.
- the module 22 is connected to the module 30 to dynamically adjust the position of an interpolation filter used to determine the estimate of the frequency response of the channel for the carriers other than the continuous and distributed pilots.
- the processing of the carriers carrying the data is ensured in a circuit 40 for processing and supplying data.
- the circuit 40 has a conventional structure and can comprise, as shown in FIG. 4, a symbol deinterlacing module 42, a so-called "demapping" module 44, a bit deinterlacing module 46, and a module 48 (FEC ) error correction.
- the output of module 48 constitutes the output S of circuit 40 and of the demodulator and provides data corresponding to the data transmitted.
- the method for refining the positioning of the FFT analysis window comprises the steps described above.
- the present invention consists in using a particular filtering function in place of the window FE previously described making it possible to take into account certain echoes outside the guard interval.
- the determination of the energy of the module response estimate of the impulse response with respect to the FE filtering function can be carried out from a portion of the module estimate of the impulse response of the channel of duration equal to the period of the estimation in module of the impulse response, that is to say equal to the useful life Tu divided by 3 in the present exemplary embodiment.
- the determination of the energy of the module estimation of the impulse response with respect to the FE filtering function can be carried out from the totality of the module estimation of the impulse response.
- the amplitudes Lj increase from the amplitude L ] _ of the first step up to a maximum amplitude LMAX corresponding to a step of index mi then decreases from the maximum amplitude LMAX to the amplitude L ⁇ of the last step of index N.
- the duration ⁇ m j_ of the step of index mi is equal to the duration of the guard interval Tg.
- ⁇ Tj + J _> ⁇ Tj at least for mi ⁇ j ⁇ (i-f-4 ⁇ Tj + J _ ⁇ Tj at least for mi-4 ⁇ j ⁇ mi
- the number of steps N is odd.
- 19 steps are shown in FIG. 7.
- the amplitude Lj and the duration ⁇ Tj are fixed as a function of the modulation used, in particular as a function of the duration of the guard interval Tg.
- the amplitudes L ⁇ _ and LJJ associated respectively with the steps of indices 1 and N are equal to zero.
- Figures 8 and 9 schematically illustrate two steps of the method for positioning the FFT analysis window according to the invention implementing the FE filtering function shown in Figure 7.
- the scales, in particular along the time axis, are not respected.
- the energy of the estimate of the impulse response with respect to the FE filtering function it is possible to use only a portion of the estimate in module of the impulse response whose duration is equal to a period of the estimation in module of the impulse response. Said portion of the estimate of the impulse response is then determined by any suitable method.
- a first step of the method then consists in searching, on said portion of the estimation in module of the impulse response of the channel, the impulse having a maximum amplitude.
- Such a pulse is associated with a reference instant tR and is considered to correspond to the main path taken by the signal received by the demodulator.
- the main path is determined by any suitable method.
- the filtering function FE is then moved relative to the instant tR from an initial instant tl, less than tR, to a final instant t2, greater than tl and less than tR, so that the index step mi is located at the initial instant tl before the main path 60, and at the final instant t2 after the main path 60.
- the energy of the estimation of the impulse response with respect to the filtering function FE is obtained by multiplying the amplitude of each echo by the amplitude of the echelon containing said echo, by multiplying the amplitude of the main path by the amplitude of the echelon containing the main path and by adding the amplitudes thus weighted.
- the estimate in modulus of the impulse response is stored in the form of a table containing indices representative of successive times, with each index being associated with a value of the estimation in modulus of the impulse response.
- An analogous table representative of the filtering function FE is then determined at the initial position at time tl.
- FIGS. 10A, 10B to 13A, 13B which illustrate the advantages of the present invention, the filtering function FE is shown, for reasons of simplicity, with a smaller number of steps than the filtering function of the figure 7.
- FIG. 10A, 10B to 13A, 13B represents a portion of the estimation in module of the impulse response of the channel, and more particularly the main path 60 and an additional echo (FIGS. 10A, 10B to 12A, 12B) or two additional echoes ( Figures 13A, 13B).
- FIGS. 10A, 10B represent two positions of the FE filtering function with respect to the module estimation of the impulse response and illustrate which position of the FE filtering function corresponds to an energy Max.
- FIGS. 10A, 10B illustrate the case in which an echo 62 substantially of the same amplitude as the main path 60 is separated from the latter by a duration less than the duration of the echelon of index mi, that is to say say of a duration less than the duration of the guard interval Tg.
- FIGS. 11A, 11B illustrate the case in which an echo 64 substantially of the same amplitude as the main path 60 is present outside the guard interval Tg, that is to say that the duration between the main path 60 and the echo 64 is greater than the duration of the guard interval Tg.
- the energy obtained is greater when the filtering function FE occupies the position shown in FIG. 11A relative to the position shown in FIG. 11B.
- FIGS. 12A, 12B illustrate the case in which an echo 66 having an amplitude less than the main path is present outside the guard interval. In this case, the energy obtained is greater when the filtering function FE occupies the position represented in FIG. 12A relative to the position represented in FIG. 12B. This means that the participation of an echo 66 of small amplitude outside the guard interval Tg is lower than the participation of the main path 60 for the positioning of the FFT analysis window.
- FIGS. 12A, 12B illustrate the case in which an echo 66 having an amplitude less than the main path. In this case, the energy obtained is greater when the filtering function FE occupies the position represented in FIG. 12A relative to the position represented in FIG. 12B. This means that the participation of an echo 66 of small amplitude outside the guard interval Tg is lower than the participation of the main path 60 for the positioning of the FFT analysis window.
- FIGS. 12A, 12B illustrate the case in which an echo 66 having an amplitude less than the main path is present outside the guard
- 13A, 13B illustrate the case in which two echoes 68, 70 of weak and identical amplitudes are symmetrically arranged on either side of the main path 60, the duration separating each echo 68, 70 and the main path 60 being greater than half the duration of the guard interval Tg.
- the energy obtained is maximum when the filtering function FE occupies the position shown in FIG. 13A relative to the position shown in FIG. 13B. This means that echoes of the same amplitude symmetrical with respect to the main path outside the guard interval have an identical participation in the positioning of the FFT analysis window.
- the present invention therefore makes it possible to take into account echoes outside the guard interval for the positioning of the FFT analysis window, while weighting the participation allocated by such echoes as a function of their amplitude and of the deviation relative to the main path, making it possible to avoid an instability of the positioning process of the FFT analysis window.
- the maximum energy position obtained from the FE filtering function can be used to refine the positioning of the interpolation filter used to determine the estimate of the frequency response of the channel for carriers other than pilots. continuous and distributed.
- the present invention is susceptible to various variants and modifications which will appear to those skilled in the art. In particular, in the example of a demodulator in FIG. 6, all the modules can be modified or replaced by suitable elements.
- input E of the circuit can directly receive a signal centered on approximately 4.5 MHz.
- the analog-to-digital converter can be external to the demodulator.
- the present invention has mainly been described in the context of digital television radio transmission, defined by standard ETSI EN 300 744, VI.4.1. However, the present invention is not limited to this standard nor to this field and can be applied in and to any device comprising a COFDM demodulator, television receiver or not.
- the demodulator according to the present invention can be used in a portable telephone.
- the FE filtering function has been described in the context of a method for processing digital signals. It is clear that the present invention can be implemented within the framework of a method for processing analog signals, the filtering function used being a continuous function then corresponding to the step function described above.
Abstract
Description
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Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/594,664 US7680195B2 (en) | 2004-03-31 | 2005-03-30 | COFDM demodulator with an optimal FFT analysis window positioning |
EP05739471A EP1733525A1 (fr) | 2004-03-31 | 2005-03-30 | Demodulateur cofdm a positionnement optimal de fenetre d'analyse fft |
US12/696,069 US7961803B2 (en) | 2004-03-31 | 2010-01-29 | COFDM demodulator with an optimal FFT analysis window positioning |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR0450634A FR2868640B1 (fr) | 2004-03-31 | 2004-03-31 | Demodulateur cofdm a positionnement optimal de fenetre d'analyse fft |
FR04/50634 | 2004-03-31 |
Related Child Applications (2)
Application Number | Title | Priority Date | Filing Date |
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US10/594,664 A-371-Of-International US7680195B2 (en) | 2004-03-31 | 2005-03-30 | COFDM demodulator with an optimal FFT analysis window positioning |
US12/696,069 Continuation US7961803B2 (en) | 2004-03-31 | 2010-01-29 | COFDM demodulator with an optimal FFT analysis window positioning |
Publications (1)
Publication Number | Publication Date |
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WO2005096581A1 true WO2005096581A1 (fr) | 2005-10-13 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/FR2005/050199 WO2005096581A1 (fr) | 2004-03-31 | 2005-03-30 | Demodulateur cofdm a positionnement optimal de fenetre d'analyse fft |
Country Status (4)
Country | Link |
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US (2) | US7680195B2 (fr) |
EP (1) | EP1733525A1 (fr) |
FR (1) | FR2868640B1 (fr) |
WO (1) | WO2005096581A1 (fr) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
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EP1566935B1 (fr) * | 2004-02-19 | 2012-07-25 | St Microelectronics S.A. | Dispositif et procédé de suppression d'interférences impulsionnelles dans un signal |
FR2897998A1 (fr) * | 2006-02-27 | 2007-08-31 | St Microelectronics Sa | Procede et dispositif d'estimation de la fonction de transfert du canal de transmission pour demodulateur cofdm |
FR2897999A1 (fr) * | 2006-02-27 | 2007-08-31 | St Microelectronics Sa | Procede et dispositif d'estimation de la fonction de transfert du canal de transmission pour demodulateur cofdm |
Citations (5)
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WO1999027671A1 (fr) * | 1997-11-25 | 1999-06-03 | Samsung Electronics Co., Ltd. | Recepteur a multiplexage frequentiel orthogonal, dans lequel le retablissement de la position de la fenetre fft est verrouille avec le reglage de l'horloge d'echantillonnage, et procede afferent |
WO2000051301A1 (fr) * | 1999-02-26 | 2000-08-31 | Stmicroelectronics S.A. | Recepteur de signaux multiporteuse a correction de defauts d'egalisation provoques par les deplacements de la fenetre trf |
WO2001069878A1 (fr) * | 2000-03-15 | 2001-09-20 | Conexant Digital Infotainment Limited | Procede de selection d'une position d'une fenetre tfr dans un recepteur cofdm |
EP1330091A1 (fr) * | 2002-01-22 | 2003-07-23 | STMicroelectronics S.A. | Procédé de sélection d'une position d'une fenêtre FFT dans un récepteur COFDM |
EP1387544A2 (fr) | 2002-07-05 | 2004-02-04 | British Broadcasting Corporation | Synchronisation dans des récepteurs multiporteuses |
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TW465234B (en) * | 1997-02-18 | 2001-11-21 | Discovision Ass | Single chip VLSI implementation of a digital receiver employing orthogonal frequency division multiplexing |
FI106592B (fi) * | 1998-05-07 | 2001-02-28 | Nokia Multimedia Network Termi | Menetelmä ja laite symbolitahdistuksen saavuttamiseksi ja ylläpitämiseksi erityisesti OFDM-järjestelmässä |
EP1063824B1 (fr) * | 1999-06-22 | 2006-08-02 | Matsushita Electric Industrial Co., Ltd. | Synchronisation de symboles dans des récepteurs multiporteuses |
GB2369016B (en) * | 2000-11-09 | 2004-06-09 | Sony Uk Ltd | Receiver |
US7058147B2 (en) * | 2001-02-28 | 2006-06-06 | At&T Corp. | Efficient reduced complexity windowed optimal time domain equalizer for discrete multitone-based DSL modems |
GB2376855A (en) * | 2001-06-20 | 2002-12-24 | Sony Uk Ltd | Determining symbol synchronisation in an OFDM receiver in response to one of two impulse response estimates |
US20040105512A1 (en) * | 2002-12-02 | 2004-06-03 | Nokia Corporation | Two step synchronization procedure for orthogonal frequency division multiplexing (OFDM) receivers |
-
2004
- 2004-03-31 FR FR0450634A patent/FR2868640B1/fr not_active Expired - Fee Related
-
2005
- 2005-03-30 EP EP05739471A patent/EP1733525A1/fr not_active Withdrawn
- 2005-03-30 WO PCT/FR2005/050199 patent/WO2005096581A1/fr active Application Filing
- 2005-03-30 US US10/594,664 patent/US7680195B2/en active Active
-
2010
- 2010-01-29 US US12/696,069 patent/US7961803B2/en not_active Expired - Fee Related
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Publication number | Priority date | Publication date | Assignee | Title |
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WO1999027671A1 (fr) * | 1997-11-25 | 1999-06-03 | Samsung Electronics Co., Ltd. | Recepteur a multiplexage frequentiel orthogonal, dans lequel le retablissement de la position de la fenetre fft est verrouille avec le reglage de l'horloge d'echantillonnage, et procede afferent |
WO2000051301A1 (fr) * | 1999-02-26 | 2000-08-31 | Stmicroelectronics S.A. | Recepteur de signaux multiporteuse a correction de defauts d'egalisation provoques par les deplacements de la fenetre trf |
WO2001069878A1 (fr) * | 2000-03-15 | 2001-09-20 | Conexant Digital Infotainment Limited | Procede de selection d'une position d'une fenetre tfr dans un recepteur cofdm |
EP1330091A1 (fr) * | 2002-01-22 | 2003-07-23 | STMicroelectronics S.A. | Procédé de sélection d'une position d'une fenêtre FFT dans un récepteur COFDM |
EP1387544A2 (fr) | 2002-07-05 | 2004-02-04 | British Broadcasting Corporation | Synchronisation dans des récepteurs multiporteuses |
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US20100135427A1 (en) | 2010-06-03 |
FR2868640A1 (fr) | 2005-10-07 |
FR2868640B1 (fr) | 2006-06-09 |
US7961803B2 (en) | 2011-06-14 |
US20070110173A1 (en) | 2007-05-17 |
EP1733525A1 (fr) | 2006-12-20 |
US7680195B2 (en) | 2010-03-16 |
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