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WO2003039088A1 - Egalisation de frequence pour systeme de transmission multitonalite - Google Patents

Egalisation de frequence pour systeme de transmission multitonalite Download PDF

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Publication number
WO2003039088A1
WO2003039088A1 PCT/EP2001/014724 EP0114724W WO03039088A1 WO 2003039088 A1 WO2003039088 A1 WO 2003039088A1 EP 0114724 W EP0114724 W EP 0114724W WO 03039088 A1 WO03039088 A1 WO 03039088A1
Authority
WO
WIPO (PCT)
Prior art keywords
transmission
data
free
signal
channels
Prior art date
Application number
PCT/EP2001/014724
Other languages
German (de)
English (en)
Inventor
J. Norbert Fliege
Steffen Trautmann
Original Assignee
Fliege J Norbert
Steffen Trautmann
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 Fliege J Norbert, Steffen Trautmann filed Critical Fliege J Norbert
Publication of WO2003039088A1 publication Critical patent/WO2003039088A1/fr

Links

Classifications

    • 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
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L25/03159—Arrangements for removing intersymbol interference operating in the frequency domain
    • 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
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L2025/0335—Arrangements for removing intersymbol interference characterised by the type of transmission
    • H04L2025/03375—Passband transmission
    • H04L2025/03414—Multicarrier
    • 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
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L2025/03433—Arrangements for removing intersymbol interference characterised by equaliser structure
    • H04L2025/03439—Fixed structures
    • H04L2025/03522—Frequency domain

Definitions

  • the present invention relates to the preambles of the independent claims.
  • the present invention is generally concerned with signal transmission.
  • BESTATIGUNGSKOPIE Errors occur because the data in the transmission channel is distorted in some way. For analog data such as speech, this is known from experience; here the intelligibility with poor telephone lines becomes less, regardless of whether the distortion occurs as an echo in the line, noise, narrowband interference as with network hum or due to strong clanking, ie generation of harmonics. Problems often grow with the length of the transmission links.
  • a number of carrier frequencies which are typically closely spaced, are provided for the transmission of data, and part of the information to be transmitted with each data packet is modulated onto each of the carrier frequencies.
  • the multiplicity of modulated carrier frequencies is fed together into the transmission channel;
  • the separation into the individual carrier frequencies and the demodulation then take place at the receiver in order to recover the output data packets.
  • the equalization is considerably simplified compared to broadband equalization, because the overall frequency range of the transmission channel can be divided into many narrow frequency bands, which can be viewed not only as quasi independent of one another, but also as free of frequency-selective behavior.
  • the simplified equalization means that the usual digital filters require less computing effort.
  • the partial signals must be selected in a certain way, namely in such a way that they are orthogonal to one another, which is possible in principle and, for example, leads to a specific choice, the frequency division. Especially ⁇ disturbing. now two effects .. Firstly, not all carrier frequencies can be used; this is the case, for example, when a strong jammer emits on or near the respective carrier frequency. Another reason for not being usable is an excessive selective attenuation of the respective frequency. This must be determined, for example when the transmission channel is set up, in order to be able to exclude the disturbed channels from being used for information transmission. It is immediately clear that the usable bandwidth of the entire available transmission channel is reduced.
  • impulses are often deformed during transmission. If a sharp, e.g. If a needle-shaped pulse is fed into a channel, these distortions lead to a “smearing” of the pulse, ie the length of the pulse expands and its shape changes. This has the result that the signal obtained for a transmitted data symbol is carried away by the receiver depends on which symbol was previously transmitted. Inter-symbol crosstalk, intersymbol interference occurs.
  • inter-channel interference can also interfere.
  • Such types of distortion now disrupt the original orthogonality. This is uncomfortable because the disturbance of orthogonality initially angestrerte "and undistorted in the ideal transmission no longer permits available simplification Filterbau easily.
  • the aim may be to shorten the guard interval duration per se in order to increase the transmission rate, or an attempt can be made, given the
  • Guard interval duration to increase the bridgeable distance.
  • the aim is, on the one hand, to equalize the channel dynamics and, on the other hand, to compensate for interference components caused by external frequency-selective and / or narrow-band interferers and the like in adjacent channels; if neither is fully achieved, an at least extensive improvement should be achieved at least for one of the two effects.
  • the object of the present invention ⁇ ' is to provide something new for industrial application.
  • a first essential aspect of the invention thus provides that, in a multi-tone transmission method, in which a plurality of transmission channels are provided, signals are fed into the transmission channel inputs in response to data symbols to be transmitted and the transmission channel outputs are evaluated for data symbol reconstruction, at least one of the intended transmission channels remaining free of transmission signals, it is provided that for the data signal reconstruction the output of at least one transmission channel free of the transmission signal is also evaluated.
  • it will typically be more precise to use an orthogonal multi-tone transmission method. She mentions the applicability for OFDM and DMT multi-tone transmission; these are special examples of multi-tone transmission methods with low frequency selectivity. The applicability of the method for filter bank methods with broadband filters should be mentioned.
  • the data transmission in a first example of the multi-tone transmission method, it is possible for the data transmission to take place guard-free; alternatively, the data transmission can take place using a guard interval.
  • the outputs of several transmission channels that are free of transmission signals can also be evaluated in the data signal reconstruction. In principle, the quality of the evaluation result increases with the number of transmission channel-free transmission channels evaluated. In the case of purely channel-related interference, a practically ideal error correction is even made possible.
  • the number of transmission channels evaluated is preferably higher, but a dozen transmission channels also evaluated give good results.
  • the signals received in the transmission channels used for transmission are linearly equalized.
  • the type of linear equalization itself must be determined for this. This can preferably be done in such a way that the actual channel response is split up into a stationary part and a transient part, the transient part being determined by evaluating the transmission signal-free transmission channels.
  • the data evaluation also partially or in particular quasi completely compensates for the noise, in particular caused by external interferers.
  • each signal that is fed into the transmission channel can be understood as the sum of the large number of sub-signals in the narrow-band channels with different carrier frequency, amplitude and phase position, which are taken into account in the multi-tone process.
  • These parameters therefore precisely define the input signal.
  • the signal can therefore only be described precisely by specifying them.
  • These parameters can be interpreted as a vector.
  • the transfer function can then be described as a matrix that indicates how each component of the vector, ie every parameter in a specific narrowband channel, changes during the transfer. If the parameters do not change, there is a uniform matrix; certain signal components are simply weakened, for example because of the channel transmits high frequencies louder than lower ones, the diagonal elements are different from one. In addition, it is also possible for one channel to cross into the other. A low frequency thus generates a signal component in a higher-frequency channel through crosstalk. This leads to non-zero elements outside the diagonal of the transfer matrix.
  • the transmission behavior of the channel can be described by its own channel matrix. Now the channel matrix can also take into account that the channel "settles", i.e. a non-zero precursor signal occurs before the actual pulse. This is the case, for example, when different frequencies spread at different speeds over the transmission channel. Likewise, the pulse can "swing out", i.e. after the actual signal has been detected, the channel is not immediately quiet again.
  • the frequency of the main signal is typically different from that in the preceding or following signal, which is also referred to as the head or tail signal.
  • the channel matrix then has three parts, namely a part that describes the precursor, a part that describes the successor and a central part between the two.
  • the signals to be transmitted are supplemented at an end region by further signal components, which in turn are determined from those parameters which correspond to the signals actually to be transmitted.
  • the vector describing the signal provided with the guard interval thus becomes cyclical in the sense that its components are cyclically adapted to one another at the top and bottom.
  • a channel matrix is first considered in which the components describing the guard interval are cut off. Based on this, a cyclical component and an error component are determined.
  • the proportion of errors is chosen so that the parts describing the head and tail parts at a certain point
  • the matrix can be broken down into a reshaped cyclical part (which describes the ideal case) and the error part.
  • the proportion of errors it is now possible to determine the proportion of errors by only evaluating the transmission channels free of transmission signals.
  • the effort to determine the proportion of errors is low because it only a few channels and accordingly matrices corresponding to a reduced dimension need to be evaluated.
  • the equalization is carried out by adding complexly weighted coefficients to the correspondingly weighted coefficients of the channels used.
  • Protection is also claimed for a device for the transmission of data using the multi-tone method, with a means for addressing a plurality of transmission channels in order to enable signals to be fed into the transmission channel inputs in response to data symbols to be transmitted and / or the transmission channel outputs to be evaluated for data symbol reconstruction , and a means for defining at least one transmission channel that remains free of transmission signals, wherein a means for data signal reconstruction is also provided, which is designed to evaluate the output of at least one transmission signal-free transmission channel. Protection is also claimed for such a device, in which the data signal reconstruction means is also designed to evaluate data transmitted with a guard interval.
  • Fig.l is a diagram of a multi-tone transmission order
  • Figure 3 illustrates a channel impulse response
  • Figure 6.7 illustrates the steps for determining the equalizer matrix relationship
  • the multi-tone transmission arrangement 1 for multi-tone transmission with guard interval is formed by a receiver 4 connected to a transmitter 3 via a transmission path 2 referred to as “channel” 2.
  • the transmission path 2 is designed to transmit signals in certain frequencies. Of these particular frequencies, discrete ones are selected for transmission, which in the present application are referred to as transmission channels. Sub-signals transmitted via these are orthogonal to one another.
  • the transmitter 3 has an input 5 for a data stream 6, which is connected to a serial-parallel converter for the parallelization and modulation of the data 7, in such a way that parallelization takes place in symbols with M components. It can be taken into account via the serial-parallel converter 7 for parallelization and modulation of the data which transmission channels of the data transmission are inaccessible due to interference. The transmitter 3 is then designed not to use such channels for the transmission of data.
  • An IDFT stage for determining an inverse discrete Fourier transformation 8 is provided at the output of the serial-parallel converter 7.
  • the outputs of the IDFT stage are fed to a parallel-serial converter 9 in a manner known per se in such a way that a guard interval is obtained, which leads to an extension of the transmission time for the transmission of a symbol.
  • the transmission signal current obtained from the parallel-serial converter 9 is converted analogously in a D / A converter 10 and fed to the channel 2.
  • sample value data blocks comprise sample value data relating to the guard interval, which are not supplied to any further evaluation, and other sample value data from which the original data stream 6 is to be obtained by evaluation.
  • the data blocks to be evaluated are now fed to a DFT stage 14 for carrying out a discrete Fourier transformation and then, with a change to be described, fed to a demodulating parallel-serial converter 15, at whose output the reconstructed data stream 6 is obtained.
  • Channel 2 now generates distortion when a signal is fed in, adds selective interference components, noise, smears the signal, etc.
  • FIG. 2 The distortions are illustrated in FIG. 2.
  • this needle-shaped signal is the highest signal in the figure.
  • Equalization can now be carried out in order to compensate for channel distortion. According to the invention, this is done by evaluating unused channels. This is explained below, reference being made to the usability of the polyphase representation known per se.
  • the respective matrix must now indicate how the element reacts when certain successive signals are fed in. This is explained on transmission path 2.
  • an MxM matrix is required without a forerunner and a follower, which indicates how the output of channel 2 comprises an M component
  • Icon responds.
  • a channel that answers immediately without distortion would correspond to a unit matrix I.
  • the duration for the transmission of a symbol i.e. a data block
  • the duration for the transmission of a symbol can be chosen to be shorter than the duration of the impulse response, and it is also assumed that the forerunner and successor parts are no longer than the symbol length. Then the output signal is longer than the input, namely by the forerunner and the follower, but that of a signal of duration M thus results in an output signal of maximum length 3M.
  • the matrix that describes a channel response is shown in FIG. 4 for the case without a guard interval. It specifies how the channel reacts to the M components of the symbol and has the size 3M and can be constructed from an MxM precursor part Ch (from " C-header), an MxM-central part Cc and an MxM trailing part Ct ( from C-trail) Certain parts of this matrix are zero, these areas are drawn in white This matrix can be broken down into the sum of a cyclical part without a forerunner and a follower and one called an error part Cerr possible in case of Guardin tervall, cf. Fig. 5, where M represents the symbol duration and Lg the guard interval duration.
  • the equalization matrix of FIG. 7 is considered, which indicates how the M transmission channels, which are to be obtained without a guard interval or after the latter have been cut off, must be corrected.
  • FIG. 7 shows a breakdown into a sum of a matrix which has only non-zero components at those diagonal locations which relate to used transmission channels and a second matrix which relates to the other locations of the matrix. Both matrices can be reduced as shown.
  • Matrix Eg re d is linked, namely via certain or determinable sizes like those that can be derived from the channel impulse response.
  • the determination of the equalizer matrix described above is particularly suitable for the equalization of channel-related interference. If frequency-selective and / or narrow-band interfering and possibly broadband interferers also occur, it is advantageous to choose a minimum means square error adaptation of the equalizer matrix coefficients which is known per se and which leads to an optimal compromise in terms of the square residual error leads in the reception symbol.
  • the correction leads to a significant improvement in the signal-to-noise ratio, as shown in FIG. 8 for a real channel with a narrow-band interfering interferer.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)

Abstract

L'invention concerne un procédé et un dispositif de transmission multitonalité. Selon l'invention, plusieurs canaux de transmission sont prévus, des signaux sont, en réponse à des symboles de données à transmettre, injectés dans les signaux d'entrée des canaux de transmission, et les signaux de sortie des canaux de transmission sont évalués pour la reconstruction des symboles de données. Au moins un des canaux de transmission prévus reste exempt de signaux de transmission et, pour la reconstruction des signaux de données, le signal de sortie d'au moins un des canaux de transmission exempts de signaux de transmission est simultanément évalué. Il est, dans un premier exemple dudit procédé de transmission multitonalité, possible que la transmission de données se fasse sans intervalle de garde. Dans une variante, la transmission de données peut se faire avec utilisation d'un intervalle de garde. Les signaux de sortie de plusieurs canaux de transmission exempts de signaux de transmission peuvent être évalués ensemble lors de la reconstruction des signaux de données. Ainsi, grâce au nombre des canaux de transmission exempts de signaux de transmission évalués, la qualité du résultat de l'évaluation est en principe augmentée.
PCT/EP2001/014724 2001-10-31 2001-12-14 Egalisation de frequence pour systeme de transmission multitonalite WO2003039088A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
EP01125998 2001-10-31
EP01125998.3 2001-10-31
DE10161420 2001-12-13
DE10161420.9 2001-12-13

Publications (1)

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WO2003039088A1 true WO2003039088A1 (fr) 2003-05-08

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004047717A1 (de) * 2004-09-30 2006-04-13 Infineon Technologies Ag Verfahren und Schaltungsanordung zur Reduzierung von RFI-Störungen
DE102004047718A1 (de) * 2004-09-30 2006-04-13 Infineon Technologies Ag Verfahren und Empfängerschaltung zur Reduzierung von Rfl-Störungen
EP1718023A2 (fr) 2005-04-28 2006-11-02 NEC Corporation Réduction d'interférence inter-symboles plus large que l'intervalle de garde en OFDM
US7961824B2 (en) 2005-03-02 2011-06-14 Mitsubishi Electric Corporation Receiver apparatus

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0969637A1 (fr) * 1998-06-29 2000-01-05 Alcatel Egalisation dans des récepteurs de signaux multiporteurs
EP1030489A1 (fr) * 1999-02-17 2000-08-23 Interuniversitair Micro-Elektronica Centrum Vzw Mehrträgersender/Empfänger

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0969637A1 (fr) * 1998-06-29 2000-01-05 Alcatel Egalisation dans des récepteurs de signaux multiporteurs
EP1030489A1 (fr) * 1999-02-17 2000-08-23 Interuniversitair Micro-Elektronica Centrum Vzw Mehrträgersender/Empfänger

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
S. TRAUTMANN, N.J. FLIEGE: "OFDM Equalization without Guard Interval", 6TH INTERNATIONAL OFDM-WORKSHOP (INOWO), 18 September 2001 (2001-09-18) - 19 September 2001 (2001-09-19), Hamburg, pages 9-1 - 9-6, XP002219888 *

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004047717A1 (de) * 2004-09-30 2006-04-13 Infineon Technologies Ag Verfahren und Schaltungsanordung zur Reduzierung von RFI-Störungen
DE102004047718A1 (de) * 2004-09-30 2006-04-13 Infineon Technologies Ag Verfahren und Empfängerschaltung zur Reduzierung von Rfl-Störungen
DE102004047717B4 (de) * 2004-09-30 2008-07-10 Infineon Technologies Ag Verfahren und Schaltungsanordung zur Reduzierung von RFI-Störungen
DE102004047718B4 (de) * 2004-09-30 2009-01-02 Infineon Technologies Ag Verfahren und Empfängerschaltung zur Reduzierung von RFI-Störungen
US7813450B2 (en) 2004-09-30 2010-10-12 Infineon Technologies Ag Method and circuit arrangement for reducing RFI interface
US8085887B2 (en) * 2004-09-30 2011-12-27 Infineon Technologies Ag Method and receiver circuit for reducing RFI interference
US7961824B2 (en) 2005-03-02 2011-06-14 Mitsubishi Electric Corporation Receiver apparatus
EP1718023A2 (fr) 2005-04-28 2006-11-02 NEC Corporation Réduction d'interférence inter-symboles plus large que l'intervalle de garde en OFDM
EP1718023A3 (fr) * 2005-04-28 2007-07-25 NEC Corporation Réduction d'interférence inter-symboles plus large que l'intervalle de garde en OFDM

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