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WO2000038387A1 - Procede de transmission de blocs de donnees sans prefixe dans l'intervalle de garde et demodules par transformation de fourier rapide avec une longueur superieure ou egale a la duree de symbole - Google Patents

Procede de transmission de blocs de donnees sans prefixe dans l'intervalle de garde et demodules par transformation de fourier rapide avec une longueur superieure ou egale a la duree de symbole Download PDF

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Publication number
WO2000038387A1
WO2000038387A1 PCT/AT1999/000311 AT9900311W WO0038387A1 WO 2000038387 A1 WO2000038387 A1 WO 2000038387A1 AT 9900311 W AT9900311 W AT 9900311W WO 0038387 A1 WO0038387 A1 WO 0038387A1
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WO
WIPO (PCT)
Prior art keywords
length
fft
guard interval
transmitted
equal
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
PCT/AT1999/000311
Other languages
German (de)
English (en)
Inventor
Robert Baldemair
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Telefonaktiebolaget LM Ericsson AB
Original Assignee
Telefonaktiebolaget LM Ericsson AB
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 Telefonaktiebolaget LM Ericsson AB filed Critical Telefonaktiebolaget LM Ericsson AB
Priority to AU19582/00A priority Critical patent/AU1958200A/en
Priority to IL14387799A priority patent/IL143877A0/xx
Priority to EP99963161A priority patent/EP1142248A1/fr
Publication of WO2000038387A1 publication Critical patent/WO2000038387A1/fr
Priority to IL143877A priority patent/IL143877A/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • H04L27/2649—Demodulators
    • H04L27/265—Fourier transform demodulators, e.g. fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators
    • 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]

Definitions

  • the invention relates to a method for the transmission of data by a multi-carrier method, e.g. DMT (Discrete Multitone) in a transmission channel in which the data in a transmitter are combined into blocks with the same number M of information symbols, modulated and transmitted by an Inverse Fast Fourier Transform (IFFT), and in a receiver by Fast- Fourier transformation (FFT) are demodulated, a guard interval for the receiver-side equalization being inserted and also transmitted between the blocks on the transmitter side, which guard interval has a length (P) which is greater than or equal to the memory length of the transmission channel.
  • DMT Discrete Multitone
  • IFFT Inverse Fast Fourier Transform
  • FFT Fast- Fourier transformation
  • a given broad frequency band is divided into a large number of narrow subchannels over which the data is transmitted.
  • the data are combined in a transmitter into information blocks of equal length and modulated by an Inverse Fast Fourier Transform (IFFT), which filters the subchannels with frequency-shifted versions of a prototype filter.
  • IFFT Inverse Fast Fourier Transform
  • the resulting transmission block is output serially by the transmitter on the transmission line.
  • IFFT Inverse Fast Fourier Transform
  • interference generally occurs between successive blocks on the receiving side.
  • a guard interval must be inserted between the individual blocks on the transmitter side.
  • the data is demodulated in the receiver by a Fast Fourier Transform (FFT), the input samples being transformed block by block into spectral values.
  • FFT Fast Fourier Transform
  • Equalization can be significantly simplified when using the FFT in the receiver if a cyclic prefix is also transmitted in the guard interval, which consists of a number of repeated data of each block, which are transmitted before the block within the guard interval.
  • the transformation length L of the FFT is equal to the length M of the data blocks sent.
  • the guard interval or the cyclic prefix must be greater than or equal to the memory length of the channel.
  • the advantage of the relatively simple equalization entails the disadvantage of the data transmitted in the prefix signal without gaining information, which takes up a portion of the available transmission power.
  • the object of the invention is therefore to provide a method of the type mentioned at the outset which enables receiver-side equalization of the transmitted transmission signal without transmission of unusable information and thus an increase in the transmission power available for data transmission.
  • this is achieved in that the guard interval is transmitted without a signal or without a prefix, and in that the demodulation in the receiver is carried out by means of a Fourier transform (FFT) with a length L which is greater than or equal to the sum of the information block length M and the length P of the guard interval.
  • FFT Fourier transform
  • the advantage of the method according to the invention is that no signal or no power has to be sent in the guard interval, as a result of which the average transmission power is reduced, but at the same time the equalization of the transmitted signal can be carried out with relatively little effort. Therefore, assuming a predetermined power density within a transmission channel, the transmission power for the information blocks can be increased.
  • a useful signal e.g. Pilot tones is transmitted, which is advantageous for clock recovery.
  • the demodulation can advantageously be carried out by extending the information block to be transformed in the receiver, which has the length M + P, by appending zeros to the transformation length L.
  • the transformation length L of the Fast Fourier Transform is twice the information block length 2-M. In this case, a very efficient implementation is possible.
  • the guard interval is sent before or after an information block.
  • Block A M [A M A M + 1 ... A 2M.1 ] T
  • Block A mM [A ⁇ M A mM + 1 ... A mM + M.
  • the data summarized in this way are modulated and transmitted by an M-point inverse fast Fourier transform (IFFT).
  • IFFT inverse fast Fourier transform
  • the transmission signal then has the following form:
  • the station aJ ⁇ $ I P > means the elements - P to M- 1 of the vector a 0.
  • the transmission signal is graphically represented when a cyclic pref is used
  • the received signal y n is the convolution of the transmitted signal and channel p
  • h k is the channel and has P + 1 coefficients.
  • the receiver splits the input sequence into blocks of length M + P and discards the first P values of each block, see FIG. 2
  • ⁇ p [VP VP + ⁇ VM + P-I]
  • FFT Fourier transformation
  • H, is the M-points FFT of the channel h k with the coefficients h P + to /.
  • M _ ⁇ ⁇ ull are desirable if Gl (8) can be factored, ie can be broken down into the product of the FFT of h k and another multiphase edge 1
  • Eq. (9) is therefore the FFT of the block a mM , which in turn is the IFFT of the data block A mM . (9) is nothing else than the date A m ⁇ + l . If you put this result in Eq. (8) one, one gets
  • Eq. (4) is nothing more than the Z-th date of the m-th block, A mM + l , multiplied by H ⁇ , that is the spectrum of the channel h k evaluated at the frequency l ⁇ -.
  • equalization is particularly simple; each received value Y t only has to be multiplied by the reciprocal of H.
  • the transformation length L of the FFT is identical to the length of the data blocks M while the length P of the guard interval or the cyclic prefix is greater than or equal to the memory length of the transmission channel.
  • the guard interval is transmitted signal-free or without a prefix, the demodulation using a Fourier transform (FFT) having a length L which is greater than or equal to the sum of the information block length M and the length P of the guard interval.
  • FFT Fourier transform
  • the guard interval can be sent before or after an information block.
  • empty guard intervals of length P are now inserted, ie in these time periods zeros are transmitted.
  • the transmission signal is
  • FIG. 3 shows the transmission signal formed in this way. If the guard interval P symbols is long and M information symbols are blocked in the transmitter, the incoming data y n are first combined in the receiver to form blocks of length M + P, as shown in FIG.
  • An FFT with a block length L of at least M + P is applied to each of these blocks of length M + P.
  • the equalization of the dispersive transmission channel takes place in the frequency domain as in the known transmission method.
  • the L elements of the vector YL are divided by samples of the spectrum of the channel.
  • the M-points FFT of the current transmission block x is equal to the transmitted data A m ] yj.
  • the upper summation limit can assume the values M - 1 to / vf + • P - 1, the associated signal elements are s m ( fl + P) + _ ⁇ to s m ( ⁇ + P) + M + _ 1 . Srn (M + P) + M to 5 - ⁇ - (tf + p) + M + p- ⁇ fall again into a guard interval and are therefore again identical zero.
  • the upper summation limit can therefore always be f
  • h is the impulse response of the channel
  • h ⁇ [h 0 h ⁇ . , , h P ].
  • the vector S ⁇ M is the IFFT of length AI of the data block A mM to be transmitted, so it applies
  • the 2 M FFT of y m ( + P ) evaluated at position 2r is therefore the rth symbol of the mth block, - m M + r , multiplied by the spectrum of channel h at frequency ⁇ 2r.
  • the same method of equalization can be used as when using a cyclic prefix.
  • the FFT of length 2H in Eq. (14) can easily be reduced to an FFT of length M.
  • the block to which the FFT of length 2M is applied has a length of + P, it is expanded to 2M with zeros.
  • the even-numbered indices of a 2 FFT can be calculated by an FFT of length -M.
  • the only additional effort is to add the two blocks. If it is taken into account that the second block contains only P elements other than zero, P additional additions are necessary.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Discrete Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Mathematical Physics (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
  • Compression, Expansion, Code Conversion, And Decoders (AREA)

Abstract

L'invention concerne un procédé de transmission de données selon un procédé à plusieurs porteuses, par exemple un procédé à multitonalité discrète (DMT = Discrete Multitone), selon lequel les données sont, dans un émetteur, assemblées en blocs présentant le même nombre de symboles d'information (M), modulées par une transformation de Fourier rapide inverse, puis transmises et démodulées, dans un récepteur, par transformation de Fourier rapide. Côté émetteur, un intervalle de garde est inséré chaque fois entre les blocs pour l'égalisation réalisée côté récepteur, et transmis avec ces blocs. Cet intervalle de garde est supérieur ou égal à la longueur de mémoire du canal de transmission. L'intervalle de garde est transmis sans signal ou sans préfixe et la démodulation se fait, dans le récepteur, par transformation de Fourier rapide avec une longueur (L) supérieure ou égale à la somme de la longueur de bloc d'information (M) et de la longueur (P) de l'intervalle de garde.
PCT/AT1999/000311 1998-12-21 1999-12-21 Procede de transmission de blocs de donnees sans prefixe dans l'intervalle de garde et demodules par transformation de fourier rapide avec une longueur superieure ou egale a la duree de symbole Ceased WO2000038387A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
AU19582/00A AU1958200A (en) 1998-12-21 1999-12-21 Method for transmitting data blocks without prefix in the guard interval, said data blocks are demodulated by means of fft with a length greater or equal the symbol period
IL14387799A IL143877A0 (en) 1998-12-21 1999-12-21 Method for transmitting data blocks without prefix in the guard interval, said data blocks are demodulated by means of fft with a length greater or equal the symbol period
EP99963161A EP1142248A1 (fr) 1998-12-21 1999-12-21 Procede de transmission de blocs de donnees sans prefixe dans l'intervalle de garde et demodules par transformation de fourier rapide avec une longueur superieure ou egale a la duree de symbole
IL143877A IL143877A (en) 1998-12-21 2001-06-20 Method for transmitting data segments without a prefix during retention time, the above data segments are regulated using FFT with a high intensity duration or equal to the signal duration

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AT0212898A AT408396B (de) 1998-12-21 1998-12-21 Verfahren zur übertragung von daten
ATA2128/98 1998-12-21

Publications (1)

Publication Number Publication Date
WO2000038387A1 true WO2000038387A1 (fr) 2000-06-29

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AT1999/000311 Ceased WO2000038387A1 (fr) 1998-12-21 1999-12-21 Procede de transmission de blocs de donnees sans prefixe dans l'intervalle de garde et demodules par transformation de fourier rapide avec une longueur superieure ou egale a la duree de symbole

Country Status (6)

Country Link
EP (1) EP1142248A1 (fr)
CN (1) CN1336063A (fr)
AT (1) AT408396B (fr)
AU (1) AU1958200A (fr)
IL (2) IL143877A0 (fr)
WO (1) WO2000038387A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003028327A3 (fr) * 2001-09-24 2003-07-31 Atheros Comm Inc Procedes de filtrage efficaces permettant d'eviter le brouillage inter-symboles et de traiter des signaux numeriques a larges bandes de garde de frequence
WO2004079958A1 (fr) 2003-03-05 2004-09-16 Fujitsu Limited Procede pour recevoir un signal de multiporteuse et recepteur multiporteuse comprenant ce signal
WO2003103574A3 (fr) * 2002-05-22 2004-09-23 Smithkline Beecham Corp Inhibiteurs de protease

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5357502A (en) * 1990-02-06 1994-10-18 France Telecom And Telediffusion De France Sa Device for the reception of digital data time frequency interlacing, notably for radio broadcasting at high bit rate towards mobile receivers with nyquist temporal window
EP0682426A2 (fr) * 1994-05-09 1995-11-15 Victor Company Of Japan, Limited Emetteur et récepteur pour MDFO
WO1996041458A1 (fr) * 1995-06-07 1996-12-19 Deutsche Thomson-Brandt Gmbh Procede et circuit destines a ameliorer la separation des porteuses lors de la transmission de signaux ofdm
WO1998051049A1 (fr) * 1997-05-02 1998-11-12 British Broadcasting Corporation Dispositif de reception en diversite de frequence et procede d'utilisation dans un recepteur de radiodiffusion audionumerique

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9218874D0 (en) * 1992-09-07 1992-10-21 British Broadcasting Corp Improvements relating to the transmission of frequency division multiplex signals
US5682376A (en) * 1994-12-20 1997-10-28 Matsushita Electric Industrial Co., Ltd. Method of transmitting orthogonal frequency division multiplex signal, and transmitter and receiver employed therefor

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5357502A (en) * 1990-02-06 1994-10-18 France Telecom And Telediffusion De France Sa Device for the reception of digital data time frequency interlacing, notably for radio broadcasting at high bit rate towards mobile receivers with nyquist temporal window
EP0682426A2 (fr) * 1994-05-09 1995-11-15 Victor Company Of Japan, Limited Emetteur et récepteur pour MDFO
WO1996041458A1 (fr) * 1995-06-07 1996-12-19 Deutsche Thomson-Brandt Gmbh Procede et circuit destines a ameliorer la separation des porteuses lors de la transmission de signaux ofdm
WO1998051049A1 (fr) * 1997-05-02 1998-11-12 British Broadcasting Corporation Dispositif de reception en diversite de frequence et procede d'utilisation dans un recepteur de radiodiffusion audionumerique

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003028327A3 (fr) * 2001-09-24 2003-07-31 Atheros Comm Inc Procedes de filtrage efficaces permettant d'eviter le brouillage inter-symboles et de traiter des signaux numeriques a larges bandes de garde de frequence
US7113559B2 (en) 2001-09-24 2006-09-26 Atheros Communications, Inc. Efficient methods for filtering to avoid inter-symbol interference and processing digital signals having large frequency guard bands
WO2003103574A3 (fr) * 2002-05-22 2004-09-23 Smithkline Beecham Corp Inhibiteurs de protease
WO2004079958A1 (fr) 2003-03-05 2004-09-16 Fujitsu Limited Procede pour recevoir un signal de multiporteuse et recepteur multiporteuse comprenant ce signal
EP1603259A4 (fr) * 2003-03-05 2010-04-07 Fujitsu Ltd Procede pour recevoir un signal de multiporteuse et recepteur multiporteuse comprenant ce signal

Also Published As

Publication number Publication date
IL143877A0 (en) 2002-04-21
AU1958200A (en) 2000-07-12
EP1142248A1 (fr) 2001-10-10
CN1336063A (zh) 2002-02-13
IL143877A (en) 2006-04-10
AT408396B (de) 2001-11-26
ATA212898A (de) 2001-03-15

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