WO2009147259A2 - Method for the transmission (modulation) and reception (demodulation) of signals in communication systems with dft-based multicarrier modulation and transmultiplexers based on sine and/or cosine modulated filter banks, and transmitting and receiving devices - Google Patents

Method for the transmission (modulation) and reception (demodulation) of signals in communication systems with dft-based multicarrier modulation and transmultiplexers based on sine and/or cosine modulated filter banks, and transmitting and receiving devices Download PDF

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WO2009147259A2
WO2009147259A2 PCT/ES2009/000295 ES2009000295W WO2009147259A2 WO 2009147259 A2 WO2009147259 A2 WO 2009147259A2 ES 2009000295 W ES2009000295 W ES 2009000295W WO 2009147259 A2 WO2009147259 A2 WO 2009147259A2
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Prior art keywords
filters
bank
modulation
transmitter
cosine
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PCT/ES2009/000295
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Spanish (es)
French (fr)
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WO2009147259A3 (en
Inventor
Fernando CRUZ ROLDÁN
Manuel Blanco Velasco
Pedro AMO LÓPEZ
José SÁEZ LANDETE
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Universidad De Alcalá
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Publication of WO2009147259A2 publication Critical patent/WO2009147259A2/en
Publication of WO2009147259A3 publication Critical patent/WO2009147259A3/en

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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
    • H04L27/2626—Arrangements specific to the transmitter only
    • H04L27/2627—Modulators
    • H04L27/2628—Inverse Fourier transform modulators, e.g. inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators
    • H04L27/2631—Inverse Fourier transform modulators, e.g. inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators with polyphase implementation
    • 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
    • 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
    • H04L27/2626—Arrangements specific to the transmitter only
    • H04L27/2627—Modulators
    • H04L27/264—Pulse-shaped multi-carrier, i.e. not using rectangular window
    • H04L27/26416—Filtering per subcarrier, e.g. filterbank multicarrier [FBMC]
    • 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
    • H04L27/2652—Fourier transform demodulators, e.g. fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators with polyphase implementation
    • 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
    • H04L27/26534—Pulse-shaped multi-carrier, i.e. not using rectangular window
    • H04L27/2654—Filtering per subcarrier, e.g. filterbank multicarrier [FBMC]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/02—Channels characterised by the type of signal
    • H04L5/023—Multiplexing of multicarrier modulation signals

Definitions

  • the invention is framed in the telecommunications sector.
  • Illustrative non-limiting examples of utility of the invention can be: broadband (xDSL (Digital Subscriber Line), Wi-Fi (Wireless Fidelity), WiMax (Wireless Interoperability for Microwave Access)) and ultra-wide (Ultra-Wide Band) communications ), mesh networks, digital audio broadcasting (DAB) and Video (DVB) - digital terrestrial television broadcasting, mobile communications (FLASH-OFDM, multicarrier-CDMA (Multiple Access Division Code)), communications through the network conventional power (Power Line Communications), Software-Defined Radio Systems, Cognitive Radio systems, systems that use OFCDM (orthogonal-frequency and code-division multiplexing), etc. In short, all those techniques that use multi-carrier modulation in any of its stages.
  • MCM multi-carrier modulation
  • OFDM Orthogonal Frequency Division Multiplexing - multiplex by division in orthogonal frequency
  • DMT Discrete Multitone Modulation - discrete multitone modulation
  • xDSL Digital Subscriber Line - digital subscriber line
  • MCM is not exempt from problems, which must be solved in the coming years: synchronization in time, and especially in frequency, high ratio between the peak power and the average power (PAPR) and the behavior against interference narrow band [Gol06].
  • PAPR peak power and the average power
  • Gol06 behavior against interference narrow band
  • MCM has been recommended in numerous standards for data transmission in broadband communication systems. As an example, it is the modulation that is recommended in the IEEE802.11a / g standard for data transmission in wireless local area networks. This standard has different transmission rates, ranging from 6 to 54 Mbps, which are achieved by modifying the convolutional encoder and the type of modulation. However, when the medium shows a low SNR, the behavior deteriorates considerably. This deterioration also contributes to the fact that the transmission frequency bands are over 2.4 and 5 GHz, which are bands that do not need a license and are shared with other devices, sometimes unwanted interference.
  • FIG. 1 shows the structure of the transmitter and receiver that is usually used in multi-carrier modulation. In its transmitting stage, it consists of a block that effects
  • FIG. 1 shows an illustrative non-limiting example of making the Parallel / Series and Series / Parallel converters. Some other equivalent implementations can be found in [Aka96, chap. 2]. The notation and representation of the elements used in these figures is identical to that used in [Vai93], both for the delay elements and for the decimation and interpolation blocks.
  • FIG. 3 shows an illustrative non-limiting example of a transmultiplexer based on a bank of maximum decimated filters with a parallel structure. The order of operations, as shown in that figure, would be as follows.
  • FIG. 4 shows an example of reception or analysis bank, implemented by means of rapid algorithms [Mal92].
  • blocks D 1 describe a butterfly implementation (for more detail, see [Mal92])
  • C is a block that performs a discrete transform of type IV cosine.
  • SUBSTITUTE SHEET (RULE 26) they are obtained from a prototype filter, and C is a block that performs a discrete transform of the type IV cosine.
  • the pairs G 1 (z) and G l + M (z) can be implemented with a joint lattice structure.
  • Figure 7 shows a general block diagram of the transmitter implemented by rapid algorithms, obtained from a bank of analysis filters, and in Figure 8 that corresponding to the receiver, obtained from a bank of synthesis filters.
  • both block diagrams are generic, and serve to describe a large number of receivers and transmitters based on transmultiplexers with filter banks.
  • the order is usually a) matrix and transformation operations; b) polyphase filters, whose coefficients are obtained from a prototype filter [Vai93], or lattice or butterfly structures; c) parallel / serial converter.
  • the stages “a” and “b” can be interchanged, and even the stage “b” can be embedded in the "a”, that is, by way of illustrative non-limiting example, the polyphase filters between matrix and transformation operations.
  • the order is usually: a) Serial / parallel converter; b) filtered polyphase or lattice or butterfly structures; c) Matrix and transformation operations. As it happens in transmission, the stages "b” and “c” present in reception can alter the order, and the "b” can also be embedded in the "c”.
  • the dispersive nature of the transmission channel destroys the orthogonality that exists between subchannels, so that interference occurs between subcarriers (ICI) and between transmitted symbols (ISI).
  • ICI subcarriers
  • ISI transmitted symbols
  • CP cyclic prefix
  • ZP zero-padded
  • Trailling zeros etc.
  • the denomination transmitter, modulator or modulation stage is used interchangeably.
  • the terms receiver, demodulator or demodulation stage are used.
  • FIG. 9 shows the typical block diagram of a communication system that includes a transmitter and a receiver that uses modulation
  • the equalization in the MCMs based on the DFT is simple, as long as the length v of the samples that make up the cyclic prefix is at least the order L of the impulse response of the equivalent transmission channel.
  • the requirement of v ⁇ L is quite restrictive, especially when transmitted at high frequencies, since the response of the channel has a large number of significant samples - they can be hundreds or thousands of samples.
  • a solution adopted to solve this problem is to design a prefilter in the receiver to shorten the length of the impulse response h of the effective channel to a convenient value. This prefilter is called the time domain equalizer (TEQ), and its objective is to "concentrate" the energy of the impulse response of the channel in a finite set of L samples [MarO6].
  • TEQ time domain equalizer
  • the objective of the cyclic prefix is to make the matrix H that characterizes the transmission medium, in the absence of noise, be a right-circulating matrix, which allows a diagonalization as follows:
  • H W 1 AW
  • ⁇ is a diagonal matrix, where its elements X 1 , O ⁇ i ⁇ (M-I), are calculated as the DFT of M points of the function that describes the equivalent channel h,
  • This invention solves some of the problems that affect other techniques proposed in advance.
  • the invention provides modulation and demodulation devices, and more generally for the transmission and / or reception of signals using various procedures that can be grouped into two blocks detailed below.
  • the invention also concerns the methods of modulation and demodulation of signals according to the procedures for transmission and reception described below.
  • the invention also concerns the devices for transmitting and / or receiving signals by carrying out said procedures.
  • the method 1 of the invention is characterized by the block diagram of the receiver shown in Figure 11.
  • the synthesis bank or its corresponding dual blocks of matrix and transformation operations and filters are used as a transmitter.
  • polyphase / lattice structures / butterfly stages so as to obtain a perfect reconstruction characteristic (Perfect Reconstruction - PR) or approach it (Near-Perfect Reconstruction N-PR).
  • the filter bank (analysis / synthesis) or the polyphase filtering blocks / lattice structures / butterfly structures and matrix operations and transformation of the transmitter and receiver form a filter side (in analysis / synthesis configuration) or a transmultiplexer (in synthesis / analysis configuration) with PR or NPR characteristics.
  • the FEQ (Frequency domain Equalizer) block is optional, and allows the correction of the effects of a transmission channel or medium located between the transmitter and the receiver.
  • the relationship between the output signals and the input signal in the receiver can be expressed as
  • X C n P ⁇ W 1 A 1 W and where y: M input data to the receiver.
  • W DFT matrix implemented by fast and efficient FFT algorithms.
  • P ra matrix that characterizes the polyphase filtering or lattice or butterfly structures of the receiver.
  • C 1x matrix that characterizes the block of matrix operations and transmitter transformation.
  • P 1x matrix that characterizes the polyphase filtering or lattice or butterfly structures of the transmitter.
  • W "1 reverse DFT matrix implemented by fast and efficient IFFT algorithms. And: transmitter output data.
  • Figure 13 shows the block diagram of the receiver 2 that must be used together with the transmitter 2 of Figure 12.
  • the relationship between the output and input signals of the receiver 2 can be characterized as follows.
  • X C 11 -P ⁇ A- '- W -y
  • y input data to the receiver.
  • W DFT matrix implemented by fast and efficient FFT algorithms.
  • C n matrix that characterizes the matrix operations and transformation of the receiver block.
  • Figure 14 shows the block diagram of a communication system that includes the receiver-1 and the cyclic prefix strategy. In the absence of noise, the input-output ratio would be:
  • Figure 15 shows the block diagram of a communication system that includes transmitter-2 and receiver-2, also using the cyclic prefix strategy.
  • the input-output ratio would be:
  • Figure 16 shows the block diagram of a communications system that includes receiver-1 and the zero-fill strategy.
  • Figure 17 shows the block diagram of a communication system that includes transmitter-2 and receiver-2, also employing the zero-fill strategy.
  • the procedures are based on taking advantage of the features provided by transmultiplexers based on filter banks, and multi-carrier modulators
  • SUBSTITUTE SHEET (RULE 26) with DFT (implemented through fast FFT algorithms), acting in conjunction with cyclic prefix strategies and zero fill.
  • Transmultiplexers based on filter banks, among other features, will provide greater spectral separation between subcarriers, which leads to more immunity against noise, including narrow-band interference of an impulsive nature.
  • Multi-carrier modulators with DFT together with the prefix or the filling of zeros, facilitate the subcarrier matching process in the frequency domain.
  • the expressions of the matrices C tt , P 1x , C n and P ra are determined by the fast execution algorithms of the filter bank in the transmultiplexer configuration being used.
  • the fast algorithms come from the way of constructing the analysis filter bank (reception) and the synthesis filter bank (transmission) and from the length of the filters.
  • a known technique for the design of filter banks or transmultiplexers is to apply a trigonometric modulation (cosine and / or sinus usually) to a prototype function (prototype filter), which can be the same function for analysis and synthesis, or different (two prototype filters).
  • the modulation schemes are very numerous, and they are the ones that finally condition the characteristics of the so-called "Matrix Operations and Transformation Block".
  • Some illustrative and non-limiting examples of modulation types may be the following: a) Cosine modulation
  • f, [n] and f, ' [n ⁇ are the filters that make up the synthesis or transmission bank (F 1 (z))
  • H 1 [n] and U 1 [n] are the filters that make up the analysis or reception bank (H 1 (z))
  • p x [n] is the prototype filter
  • k x and k 2 are constants.
  • SUBSTITUTE SHEET (RULE 26)
  • the specifications of the prototype filter depend on the particular application for which the method of the invention is used, and the length of the prototype filter also determines the matrix and transformation operations block.
  • the polyphase filter block consists of a series of filters in parallel.
  • the coefficients that characterize these filters are obtained from a prototype filter of different shapes [Cro83, Vai93, FI ⁇ 94, MitO1, DinO2]. In turn, they can be implemented directly, transversely, recursively, in lattice, or grouped in pairs, as indicated, and are not excluded in the proposed procedures.
  • P (z) is the function of the prototype filter system
  • the decomposition into M type 1 G 1 (z M ) polyphase filters would be GA z ) p [nM + for 0 ⁇ ⁇ M -l.
  • the butterfly structure block is usually cascaded.
  • An illustrative non-limiting example is the block diagram of Figure 4.
  • Figure 1 Block diagram of the stages of (a) transmission and (b) reception for MCM.
  • Figure 2. Block diagram of an implementation of the converters
  • Figure 7. General block diagram of a transmitter with filter banks using fast algorithms.
  • Figure 8. General block diagram of a receiver with filter banks using fast algorithms.
  • Figure 9. Block diagram of a communication system that uses multi-carrier modulation and cyclic prefix.
  • FIG. 10 Block diagram of a communications system that uses multi-carrier modulation and zero fill.
  • Block diagram (a) direct and (b) with fast algorithms of receiver-1.
  • Figure 12. Block diagram (a) direct and (b) with fast transmitter algorithms
  • FIG. 13 Block diagram (a) direct and (b) with fast algorithms of receiver-2.
  • Figure 14 Block diagram of a communication system using the receiver-1 and cyclic prefix.
  • Figure 15 Block diagram of a communication system that uses transmitter-2 and receiver-2, together with cyclic prefix.
  • FIG. 16 Block diagram of a communication system that uses receiver-1 and zero-fill.
  • Figure 17 Block diagram of a communications system that uses transmitter-2 and receiver-2, along with zero-fill.
  • Figure 18. Block diagram of an example of transmitter-1.
  • Figure 19. Block diagram of an example of receiver-1.
  • Figure 20. Module of the frequency response in certain subchannels of the DFT bank.
  • Figure 21. Module of the frequency response in certain subchannels of the system proposed in the example of procedure 1.
  • Figure 22. Block diagram of an example of transmitter-2.
  • Figure 24 Module of the frequency response in certain subchannels of the system proposed in the example of procedure 2.
  • Example of Procedure 1 and cyclic prefix Figures 18 and 19 show respectively the block diagrams of a transmitter and a specific receiver using the method 1 of the invention. In these figures, neither the cyclic prefix inclusion block nor the selection of the appropriate samples in the receiver are represented.
  • the transmultiplexer that serves as the basis of the design is obtained from a maximum decimated filter bank near the perfect reconstruction (NPR), with a 64-channel parallel structure, where the reception filters -I)) and transmission (f k [n], 0 ⁇ k ⁇ (M -I)) are obtained from of a prototype filter , using the following expressions:
  • ⁇ c diagonal matrix MxM that implies multiplying each branch by a constant value.
  • the transmission filters are temporarily reflected versions of the reception filters, and the transmission matrix is obtained from
  • Figure 20 shows the module of the frequency response of some subbands of the filter bank that is obtained from the DFT (the standardized one), with an attenuation with maximums of about 13.5 dBs in each subchannel.
  • Figure 21 the module of the response of some subbands of the additional filter bank added in the proposed procedure is shown. Attenuations of more than 90 dBs per subchannel are appreciated.
  • Example of Procedure 2 and cyclic prefix Figures 22 and 23 respectively show the block diagrams of a transmitter and a specific receiver using the method 2 of the invention. In these figures, neither the cyclic prefix inclusion block nor the selection of the appropriate samples in the receiver are represented.
  • the transmultiplexer that serves as the basis of the design is also obtained from a bank of maximum decimated filters near the perfect reconstruction (NPR) 1 with a parallel structure, of 64 channels, where the reception filters (h k [n] , 0 ⁇ k ⁇ (M - ⁇ )) and transmission (f k [n], 0 ⁇ k ⁇ (M -I)) are obtained as indicated above.
  • the transmission filters are also temporarily reflected versions of the reception filters, and the transmission matrix is also obtained from
  • the efficient algorithm is also expressed in terms of a discrete transform of the cosine, type IV, performed by efficient algorithms, a diagonal matrix MxM that implies multiplying each branch by a constant value, the matrices I and J, and a diagonal matrix with the polyphase components.
  • Figure 24 shows the module of the response of some subbands of the additional filter bank added in the proposed procedure. Attenuations of almost 100 dBs per subchannel are appreciated.

Abstract

The invention relates to a method for the transmission and reception of a multicarrier signal. According to the invention, the following steps are performed in the transmitter, namely: processing of the input subcarrier signals using a rapid algorithm obtained from a synthesis filter bank, in which each of the filters is obtained by means of a cosine, sine or mixed trigonometric modulation applied to a prototype filter; and parallel/series conversion. In addition, the following steps are performed in the receiver, namely: series/parallel conversion; implementation of the discrete Fourier transform (FFT); frequency-domain equalizer (FEQ); processing of signals using a rapid algorithm obtained from an analysis filter bank, in which each of the filters is obtained by means of a cosine, sine or mixed trigonometric modulation applied to a prototype filter.

Description

PROCEDIMIENTO DE TRANSMISIÓN (MODULACIÓN) Y RECEPCIÓN (DEMODULACIÓN) DE SEÑALES EN SISTEMAS DE COMUNICACIÓN CON PROCEDURE FOR TRANSMISSION (MODULATION) AND RECEPTION (DEMODULATION) OF SIGNS IN COMMUNICATION SYSTEMS WITH
MODULACIÓN M U LTI PORTADORA DFT Y TRANSMULTIPLEXADORES BASADOS EN BANCOS DE FILTROS MODULADOS EN SENO Y/O COSENO, DISPOSITIVOS PARA TRANSMITIR Y RECIBIRMODULATION M U LTI CARRIER DFT AND TRANSMULTIPLEXERS BASED ON BANKS OF FILTERS MODULATED IN BREAST AND / OR COSINE, DEVICES FOR TRANSMITTING AND RECEIVING
SECTOR DE LA TÉCNICASECTOR OF THE TECHNIQUE
La invención se encuentra enmarcada en el sector de las telecomunicaciones. Ejemplos ilustrativos no limitativos de utilidad de Ia invención pueden ser: comunicaciones de banda ancha (xDSL (Digital Subscriber Line), Wi-Fi (Wireless Fidelity), WiMax (Wireless Interoperability for Microwave Access)) y ultra-ancha (Ultra- Wide Band), redes mesh, radiodifusión digital de audio (DAB) y de Video (DVB) - radiodifusión de televisión digital terrestre-, comunicaciones móviles (FLASH-OFDM, multicarrier-CDMA (Code División Múltiple Access)), comunicaciones a través de Ia red eléctrica convencional (Power Line Communications), Sistemas Software-Defined Radio, sistemas Cognitive Radio, sistemas que empleen OFCDM (orthogonal- frequency and code-division multiplexing), etc. En definitiva, todas aquellas técnicas que empleen modulación multiportadora en alguna de sus etapas.The invention is framed in the telecommunications sector. Illustrative non-limiting examples of utility of the invention can be: broadband (xDSL (Digital Subscriber Line), Wi-Fi (Wireless Fidelity), WiMax (Wireless Interoperability for Microwave Access)) and ultra-wide (Ultra-Wide Band) communications ), mesh networks, digital audio broadcasting (DAB) and Video (DVB) - digital terrestrial television broadcasting, mobile communications (FLASH-OFDM, multicarrier-CDMA (Multiple Access Division Code)), communications through the network conventional power (Power Line Communications), Software-Defined Radio Systems, Cognitive Radio systems, systems that use OFCDM (orthogonal-frequency and code-division multiplexing), etc. In short, all those techniques that use multi-carrier modulation in any of its stages.
ESTADO DE LA TÉCNICASTATE OF THE TECHNIQUE
Las técnicas de acceso al medio basadas en Ia modulación multiportadora (MCM), entre las que se encuentran OFDM (Orthogonal Frequency División Multiplexing - múltiplex por división en frecuencia ortogonal) para sistemas inalámbricos, y DMT (Discrete Multitone Modulation - modulación multitono discreta) para tecnologías xDSL (Digital Subscriber Line - línea de abonado digital), van a aumentar su implantación en las futuras generaciones de sistemas de comunicación de banda ancha. Entre sus principales ventajas, se pueden citar su efectividad para combatir el efecto multitrayecto o los desvanecimientos selectivos en frecuencia. Además, cuando se trata de canales que varían lentamente con el tiempo, se puede mejorar el rendimiento del sistema con un incremento significativo de Ia tasa de transmisión por subportadora. Bien es cierto que MCM no está exenta de inconvenientes, los cuales deben ser solventados en los próximos años: sincronización en tiempo, y especialmente en frecuencia, elevada relación entre Ia potencia de pico y Ia potencia promedio (PAPR) y el comportamiento frente a interferencias de banda estrecha [Gol06]. Uno de las principales características de este invento consiste en Ia mejora de algunas de estasMedia access techniques based on multi-carrier modulation (MCM), among which are OFDM (Orthogonal Frequency Division Multiplexing - multiplex by division in orthogonal frequency) for wireless systems, and DMT (Discrete Multitone Modulation - discrete multitone modulation) for xDSL technologies (Digital Subscriber Line - digital subscriber line), will increase their implementation in future generations of broadband communication systems. Among its main advantages, its effectiveness can be cited to combat the multipath effect or the selective fades in frequency. In addition, when it comes to channels that vary slowly over time, the performance of the system can be improved with a significant increase in the transmission rate per subcarrier. It is true that MCM is not exempt from problems, which must be solved in the coming years: synchronization in time, and especially in frequency, high ratio between the peak power and the average power (PAPR) and the behavior against interference narrow band [Gol06]. One of the main features of this invention is the improvement of some of these
HOJA DE SUSTITUCIÓN (REGLA 26) deficiencias, aportando varias soluciones novedosas que denominamos modulación multiportadora embebida (Embedded Multicarrier Modulation) acrónimo E-MCM.SUBSTITUTE SHEET (RULE 26) deficiencies, providing several innovative solutions that we call Embedded Multicarrier Modulation (acronym E-MCM).
MCM ha sido recomendada en numerosos estándares para transmisión de datos en sistemas de comunicación de banda ancha. A modo de ejemplo, es Ia modulación que se recomienda en el estándar IEEE802.11a/g para transmisión de datos en redes de área local inalámbricas. Dicho estándar, presenta diferentes tasas de transmisión, que van desde los 6 a los 54 Mbps, las cuales se consiguen modificando el codificador convolucional y el tipo de modulación. Sin embargo, cuando el medio presenta una baja SNR, el comportamiento se deteriora considerablemente. A este deterioro también contribuye el hecho de que las bandas de frecuencia de transmisión se sitúan sobre los 2,4 y 5 GHz, las cuales son bandas que no necesitan licencia y que se comparten con otros dispositivos, apareciendo en ocasiones interferencias indeseadas.MCM has been recommended in numerous standards for data transmission in broadband communication systems. As an example, it is the modulation that is recommended in the IEEE802.11a / g standard for data transmission in wireless local area networks. This standard has different transmission rates, ranging from 6 to 54 Mbps, which are achieved by modifying the convolutional encoder and the type of modulation. However, when the medium shows a low SNR, the behavior deteriorates considerably. This deterioration also contributes to the fact that the transmission frequency bands are over 2.4 and 5 GHz, which are bands that do not need a license and are shared with other devices, sometimes unwanted interference.
Esta modulación también ha sido adoptada en un gran número de estándares: DAB - Digital Audio Broadcasting, DVB -Digital Video Broadcasting, las redes inalámbricas de área local (WLAN), —basadas en los estándares IEEE 802.11a y g e IEEE802.16, ETSI BRAN HIPERLAN/2 — , o Ia transmisión de datos sobre bucle de abonado digital asimétrico (ADSL, ADSL2 y ADSL2+) y de muy alta velocidad (VDSL). La figura 1 muestra Ia estructura del transmisor y del receptor que habitualmente se utiliza en modulación multiportadora. En su etapa transmisora, consta de un bloque que efectúaThis modulation has also been adopted in a large number of standards: DAB - Digital Audio Broadcasting, DVB-Digital Video Broadcasting, Wireless Local Area Networks (WLAN), —based on IEEE 802.11ayge IEEE802.16, ETSI BRAN HIPERLAN standards / 2 -, or the transmission of data on an asymmetric digital subscriber loop (ADSL, ADSL2 and ADSL2 +) and very high speed (VDSL). Figure 1 shows the structure of the transmitter and receiver that is usually used in multi-carrier modulation. In its transmitting stage, it consists of a block that effects
-una transformada discreta de Fourier inversa (IDFT) de M puntos -donde M es el número de subcanales o subportadoras-, habitualmente implementada a través de algoritmos rápidos (Inverse Fast Fourier Transform - IFFT). Así mismo, también hay un convertidor paralelo serie para conformar una señal y, que puede ser transmitida o procesada a través de otros sistemas. La etapa de recepción, por su parte, está conformada por un convertidor serie/paralelo, y posteriormente un bloque que efectúa Ia transformada discreta de Fourier (DFT), también implementada habitualmente a través de algoritmos rápidos (FFT) que conllevan un ahorro en el número de operaciones que hay que realizar para obtener Ia señal de salida resultante. La figura 2 muestra un ejemplo ilustrativo no limitativo de realizar los convertidores Paralelo/Serie y Serie/Paralelo. Algunas otras implementaciones equivalentes se pueden encontrar en [Aka96, cap. 2]. La notación, y representación de los elementos que se emplean en estas figuras es idéntica a Ia que se utiliza en [Vai93], tanto para los elementos de retardo como para los bloques de diezmado y de interpolación.-a discrete inverse Fourier transform (IDFT) of M points -where M is the number of subchannels or subcarriers-, usually implemented through fast algorithms (Inverse Fast Fourier Transform - IFFT). Likewise, there is also a serial parallel converter to form a signal and, which can be transmitted or processed through other systems. The reception stage, meanwhile, is made up of a serial / parallel converter, and subsequently a block that performs the discrete Fourier transform (DFT), also usually implemented through rapid algorithms (FFT) that lead to savings in the number of operations to be performed to obtain the resulting output signal. Figure 2 shows an illustrative non-limiting example of making the Parallel / Series and Series / Parallel converters. Some other equivalent implementations can be found in [Aka96, chap. 2]. The notation and representation of the elements used in these figures is identical to that used in [Vai93], both for the delay elements and for the decimation and interpolation blocks.
HOJA DE SUSTITUCIÓN (REGLA 26) Es bien conocido que Ia DFT se puede interpretar desde Ia teoría de bancos de filtros: es un banco de filtros modulado exponencialmente, en el que el filtro prototipo es una ventana rectangular de longitud M [Vai93, MitO1]. Concretamente, cada uno de los filtros del banco presenta una discriminación muy limitada (13.5 dB por subcanal). Este efecto trae consigo numerosas desventajas, por ejemplo: las interferencias de radio frecuencia (RFI), que ocasionan las emisoras de radio o los radioaficionados, suelen ser más nocivas; existe una elevada paradiafonía o diafonía de entorno cercano (NEXT) en DSL; además también se producen degradaciones en el funcionamiento de los sistemas de comunicación [Gov99, Mar98, San95]. En definitiva, el comportamiento en entornos ruidosos de los sistemas OFDM/DMT basados en Ia DFT, especialmente con ruido impulsivo, no es en absoluto robusto ni fiable. Para solventar estos últimos problemas, se han propuesto diversas técnicas alternativas, principalmente basadas en el uso de bancos de filtros distintos del DFT con una configuración de transmultiplexor [Gov99, Mar98, San95, CheO2, Sio02, CruO3, FarO3b, MirO3, Vio04, WN04, LinO6, LinO7]. La figura 3 muestra un ejemplo ilustrativo no limitativo de transmultiplexor basado en un banco de filtros de diezmado máximo con estructura en paralelo. El orden de las operaciones, tal y como se muestra en dicha figura, sería el siguiente. En transmisión a) interpolar cada señal subportadora, b) filtrar a través de los filtros de transmisión o de síntesis F1 (z), 0 < i ≤ (M -l) , y c) conformar Ia señal y como Ia suma de las salidas obtenidas de cada filtro: y - y o + y\ + — h ^M -i - ^n recepción: a) filtrar Ia señal de entrada con los filtros de recepción o de análisis H1 (z), O ≤ i ≤ (M -l) , y b) diezmar a continuación cada una de las salidas.SUBSTITUTE SHEET (RULE 26) It is well known that DFT can be interpreted from the theory of filter banks: it is an exponentially modulated filter bank, in which the prototype filter is a rectangular window of length M [Vai93, MitO1]. Specifically, each of the bank's filters has a very limited discrimination (13.5 dB per subchannel). This effect entails numerous disadvantages, for example: radio frequency interference (RFI), which is caused by radio stations or amateur radio stations, is usually more harmful; there is a high level of near-diaphony or crosstalk (NEXT) in DSL; in addition, there are also degradations in the functioning of communication systems [Gov99, Mar98, San95]. In short, the behavior in noisy environments of OFDM / DMT systems based on DFT, especially with impulsive noise, is not at all robust or reliable. To solve these latter problems, various alternative techniques have been proposed, mainly based on the use of filter banks other than DFT with a transmultiplexer configuration [Gov99, Mar98, San95, CheO2, Sio02, CruO3, FarO3b, MirO3, Vio04, WN04 , LinO6, LinO7]. Figure 3 shows an illustrative non-limiting example of a transmultiplexer based on a bank of maximum decimated filters with a parallel structure. The order of operations, as shown in that figure, would be as follows. In transmission a) interpolate each subcarrier signal, b) filter through the transmission or synthesis filters F 1 (z), 0 <i ≤ (M -l), and c) form the signal and as the sum of the outputs obtained from each filter: y - yo + y \ + - h ^ M -i - ^ n reception: a) filter the input signal with the reception or analysis filters H 1 (z), O ≤ i ≤ (M -l), and b) decimate each of the outputs below.
Algunos de estos bancos de filtros se pueden realizar de forma más eficiente, de manera que se vea reducida considerablemente Ia carga computacional. En Ia figura 4 se muestra un ejemplo de banco de recepción o análisis, implementado mediante algoritmos rápidos [Mal92]. En dicha figura, los bloques D1 describen una implementación en mariposa (para más detalle, ver [Mal92]), y C es un bloque que lleva a cabo una transformada discreta del coseno tipo IV.Some of these filter banks can be performed more efficiently, so that the computational load is considerably reduced. Figure 4 shows an example of reception or analysis bank, implemented by means of rapid algorithms [Mal92]. In said figure, blocks D 1 describe a butterfly implementation (for more detail, see [Mal92]), and C is a block that performs a discrete transform of type IV cosine.
En las figuras 5 y 6 se muestran otros ejemplos de transmisor y receptor [Vio04]. En dichas figuras, Ge (-z2) , 0 ≤ £ ≤ (2M -l) , son los filtros polifase cuyos coeficientes seOther examples of transmitter and receiver [Vio04] are shown in Figures 5 and 6. In these figures, G e (-z 2 ), 0 ≤ £ ≤ (2M -l), are the polyphase filters whose coefficients are
HOJA DE SUSTITUCIÓN (REGLA 26) obtienen a partir de un filtro protipo, y C es un bloque que lleva a cabo una transformada discreta del coseno tipo IV. Además, en determinadas ocasiones, los pares G1 (z) y Gl+M (z) se pueden implementar con una estructura en celosía conjunta. En [Mal92, Koi92, Vai93, FN94, Lin 95, Str96, MitO1 , DinO2, FarO3a, FarO3b, Vio04, CruO4, LinO6] se pueden encontrar un número considerable de bancos de filtros implementados mediante algoritmos rápidos. En Ia figura 7 se muestra un diagrama de bloques general del transmisor implementado mediante algoritmos rápidos, obtenido a partir de un banco de filtros de análisis, y en Ia figura 8 el correspondiente al receptor, obtenido a partir de un banco de filtros de síntesis. Ambos diagramas de bloques son genéricos, y sirven para describir un gran número de receptores y transmisores basados en transmultiplexores con bancos de filtros. En transmisión, el orden suele ser a) operaciones matriciales y de transformación; b) filtros polifase, cuyos coeficientes se obtienen a partir de un filtro prototipo [Vai93], o estructuras en celosía o en mariposa; c) convertidor paralelo/serie. Las etapas "a" y "b" pueden intercambiarse, e incluso Ia etapa "b" puede estar embebida en Ia "a", es decir, a modo de ejemplo ilustrativo no limitativo, los filtros polifase entre operaciones matriciales y de transformación. En recepción, el orden suele ser: a) Convertidor Serie/paralelo; b) filtrado polifase ó estructuras en celosía o en mariposa; c) Operaciones matriciales y de transformación. Al igual que ocurre en transmisión, las etapas "b" y "c" presentes en recepción pueden alterar el orden, y Ia "b" también puede encontrarse embebida en Ia "c".SUBSTITUTE SHEET (RULE 26) they are obtained from a prototype filter, and C is a block that performs a discrete transform of the type IV cosine. In addition, on certain occasions, the pairs G 1 (z) and G l + M (z) can be implemented with a joint lattice structure. In [Mal92, Koi92, Vai93, FN94, Lin 95, Str96, MitO1, DinO2, FarO3a, FarO3b, Vio04, CruO4, LinO6] a considerable number of filter banks implemented by rapid algorithms can be found. Figure 7 shows a general block diagram of the transmitter implemented by rapid algorithms, obtained from a bank of analysis filters, and in Figure 8 that corresponding to the receiver, obtained from a bank of synthesis filters. Both block diagrams are generic, and serve to describe a large number of receivers and transmitters based on transmultiplexers with filter banks. In transmission, the order is usually a) matrix and transformation operations; b) polyphase filters, whose coefficients are obtained from a prototype filter [Vai93], or lattice or butterfly structures; c) parallel / serial converter. The stages "a" and "b" can be interchanged, and even the stage "b" can be embedded in the "a", that is, by way of illustrative non-limiting example, the polyphase filters between matrix and transformation operations. At reception, the order is usually: a) Serial / parallel converter; b) filtered polyphase or lattice or butterfly structures; c) Matrix and transformation operations. As it happens in transmission, the stages "b" and "c" present in reception can alter the order, and the "b" can also be embedded in the "c".
La naturaleza dispersiva del canal de transmisión destruye Ia ortogonalidad que existe entre subcanales, de manera que en el receptor se produce interferencia entre subportadoras (ICI) y entre símbolos (ISI) transmitidos. Para combatir estos efectos existen diversas estrategias. Por ejemplo, Ia adición de un prefijo cíclico (CP) [MuqO2, WanOO] con el objetivo de facilitar Ia igualación en Ia etapa de recepción. Otra estrategia utilizada para combatir los anteriores efectos, consiste en un rellenado de ceros (Zero-padded (ZP), Trailling zeros, etc) [MuqO2, WanOO]. En todo este documento se emplea indistintamente Ia denominación transmisor, modulador o etapa de modulación. Del mismo modo, se emplean los términos receptor, demodulador o etapa de demodulación.The dispersive nature of the transmission channel destroys the orthogonality that exists between subchannels, so that interference occurs between subcarriers (ICI) and between transmitted symbols (ISI). To combat these effects there are several strategies. For example, the addition of a cyclic prefix (CP) [MuqO2, WanOO] in order to facilitate equalization in the reception stage. Another strategy used to combat the aforementioned effects is a zero-padded (ZP), Trailling zeros, etc.) [MuqO2, WanOO]. Throughout this document the denomination transmitter, modulator or modulation stage is used interchangeably. Similarly, the terms receiver, demodulator or demodulation stage are used.
Transmisión con Prefijo Cíclico (CP) En Ia figura 9 se muestra el diagrama de bloques típico de un sistema de comunicaciones que incluye un transmisor y un receptor que emplea modulaciónTransmission with Cyclic Prefix (CP) Figure 9 shows the typical block diagram of a communication system that includes a transmitter and a receiver that uses modulation
HOJA DE SUSTITUCIÓN (REGLA 26) multiportadora y utiliza prefijo cíclico (para detalles de funcionamiento del CP, ver [MuqO2, WanOO]). En dicha figura, Ia misión de los diferentes bloques que aparecen se explica a continuación: a) bloque CP inserta el prefijo cíclico; b) c representa al canal de transmisión; c) TEQ (Time-Domain Equalizer) indica un igualador en el dominio del tiempo, cuya misión es concentrar Ia energía del canal equivalente h en un conjunto finito de muestras, de forma que el uso del prefijo cíclico sea efectivo (este bloque es opcional, se detalla brevemente a continuación, y si no se utiliza, en ausencia de ruido, h = c ); d) R-CP (Remove-Cyclic Prefix) elimina las muestras recibidas no válidas; e) FEQ (Frequency-domain Equalizer) representa un igualador en el dominio de Ia frecuencia, que básicamente consiste en multiplicar cada subportadora por una constante l/A, , que como veremos a continuación está relacionada con Ia respuesta al impulso del canal equivalente h a través de su DFT de M puntos.SUBSTITUTE SHEET (RULE 26) multi-carrier and use cyclic prefix (for details of CP operation, see [MuqO2, WanOO]). In said figure, the mission of the different blocks that appear is explained below: a) CP block inserts the cyclic prefix; b) c represents the transmission channel; c) TEQ (Time-Domain Equalizer) indicates an equalizer in the time domain, whose mission is to concentrate the energy of the equivalent channel h in a finite set of samples, so that the use of the cyclic prefix is effective (this block is optional , is briefly detailed below, and if not used, in the absence of noise, h = c); d) R-CP (Remove-Cyclic Prefix) removes invalid samples received; e) FEQ (Frequency-domain Equalizer) represents an equalizer in the frequency domain, which basically consists of multiplying each subcarrier by a constant l / A, which, as we will see below, is related to the impulse response of the equivalent channel has through its DFT of M points.
En ausencia de ruido, Ia igualación en los MCM basados en Ia DFT es sencilla, siempre y cuando Ia longitud v de las muestras que conforman el prefijo cíclico sea al menos el orden L de Ia respuesta al impulso del canal de transmisión equivalente. Sin embargo, el requisito de v ≥ L es bastante restrictivo, especialmente cuando se transmite a frecuencias elevadas, ya que Ia respuesta del canal presenta un gran número de muestras significativas -pueden ser cientos o miles de muestras. Una solución adoptada para solventar este problema consiste en diseñar un prefiltro en el receptor para acortar Ia longitud de Ia respuesta al impulso h del canal efectivo hasta un valor conveniente. Este prefiltro se denomina igualador en el dominio del tiempo (TEQ), y su objetivo es "concentrar" Ia energía de Ia respuesta al impulso del canal en un conjunto finito de L muestras [MarO6]. Como es bien conocido, el objetivo del prefijo cíclico consiste en hacer que Ia matriz H que caracteriza al medio de transmisión, en ausencia de ruido, sea una matriz circulante a derechas, que admita una diagonalización del siguiente modo:In the absence of noise, the equalization in the MCMs based on the DFT is simple, as long as the length v of the samples that make up the cyclic prefix is at least the order L of the impulse response of the equivalent transmission channel. However, the requirement of v ≥ L is quite restrictive, especially when transmitted at high frequencies, since the response of the channel has a large number of significant samples - they can be hundreds or thousands of samples. A solution adopted to solve this problem is to design a prefilter in the receiver to shorten the length of the impulse response h of the effective channel to a convenient value. This prefilter is called the time domain equalizer (TEQ), and its objective is to "concentrate" the energy of the impulse response of the channel in a finite set of L samples [MarO6]. As is well known, the objective of the cyclic prefix is to make the matrix H that characterizes the transmission medium, in the absence of noise, be a right-circulating matrix, which allows a diagonalization as follows:
H = W 1 A W donde Λ es una matriz diagonal, donde sus elementos X1 , O ≤ i ≤ (M -I) , se calculan como Ia DFT de M puntos de Ia función que describe al canal equivalente h ,H = W 1 AW where Λ is a diagonal matrix, where its elements X 1 , O ≤ i ≤ (M-I), are calculated as the DFT of M points of the function that describes the equivalent channel h,
M-I _ 2π_ es decir, Λ = diag{Λ,, X1, - V.} con 4 = ∑ M"K M . 0 < / ≤ (M -l) . n=0MI _ 2π_ that is, Λ = diag {Λ ,, X 1 , - V.} with 4 = ∑ M "K M. 0 </ ≤ (M -l). N = 0
HOJA DE SUSTITUCIÓN (REGLA 26) Rellenado de Ceros (ZP)SUBSTITUTE SHEET (RULE 26) Filling Zeros (ZP)
Otra estrategia utilizada para convertir Ia matriz del canal en circulante a derechas consiste en Ia inserción de ceros (Zero Padded, Zero Padding, Trailing Zeros) en el convertidor paralelo serie [MuqO2, WanOO]. En Ia figura 10 se representa una de las posibles estrategias (para más detalle del funcionamiento de ZP, ver [MuqO2, WanOO]). La matriz H también se puede diagonalizar tal y como se indica con anterioridad.Another strategy used to convert the matrix of the channel into working right is the insertion of zeros (Zero Padded, Zero Padding, Trailing Zeros) in the parallel series converter [MuqO2, WanOO]. Figure 10 shows one of the possible strategies (for more detail on the operation of ZP, see [MuqO2, WanOO]). The matrix H can also be diagonalized as indicated above.
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Englewood Cliffs, NJ, 1993. [Vio04] Ari Viholainen, Modulated filter bank design for Communications signal processing. Ph. D. Dissertation, Tampere University of Technology, Tampere (Finland), September 2004.Englewood Cliffs, NJ, 1993. [Vio04] Ari Viholainen, Modulated filter bank design for Communications signal processing. Ph. D. Dissertation, Tampere University of Technology, Tampere (Finland), September 2004.
[WanOO] Z. Wang and G. B. Giannakis, "Wireless multicarrier Communications. Where[WanOO] Z. Wang and G. B. Giannakis, "Wireless multicarrier Communications. Where
Fourier meets Shannon," IEEE Signal Processing Magazine, VoI. 17, No. 3, pp. 29-48, May 2000.Fourier meets Shannon, "IEEE Signal Processing Magazine, VoI. 17, No. 3, pp. 29-48, May 2000.
[WN04] M. R. Wilbur, T. N. Davidson, and J. P. ReNIy, "Efficient design of oversampled NPR GDFT filterbanks," IEEE Transactions on Signal Processing, VoI. 52, No.[WN04] M. R. Wilbur, T. N. Davidson, and J. P. ReNIy, "Efficient design of oversampled NPR GDFT filterbanks," IEEE Transactions on Signal Processing, VoI. 52, No.
7, pp. 1947-1963, JuIy 2004.7, pp. 1947-1963, July 2004.
DESCRIPCIÓN DE LA INVENCIÓN Esta invención solventa algunos de los problemas que afectan a otras técnicas propuestas con antelación. Los procedimientos de modulación y demodulación propuestos en Ia invención y para una relación señal a ruido fija, comparando con otros esquemas de modulación previamente propuestos por otros autores/inventores: a) permite separar con mayor eficiencia espectral Ia información en cada una de las subportadoras; b) aumenta Ia robustez del sistema, disminuyendo Ia probabilidad de error; c) permite mejorar el régimen binario, Io cual se traduce en Ia transmisión/recepción de más información en el mismo intervalo temporal; d) es más inmune a las interferencias de banda estrecha; e) facilita las comunicaciones secretas seguras.DESCRIPTION OF THE INVENTION This invention solves some of the problems that affect other techniques proposed in advance. The modulation and demodulation procedures proposed in the invention and for a signal to fixed noise ratio, comparing with other modulation schemes previously proposed by other authors / inventors: a) allows the information to be separated with greater spectral efficiency in each of the subcarriers; b) increases the robustness of the system, decreasing the probability of error; c) it allows to improve the binary regime, which translates into the transmission / reception of more information in the same time interval; d) is more immune to narrowband interference; e) facilitates secure secret communications.
HOJA DE SUSTITUCIÓN (REGLA 26) Para conseguir los objetivos anteriores, Ia invención proporciona dispositivos de modulación y desmodulación, y más generalmente de transmisión y/o recepción de señales empleando diversos procedimientos que pueden ser agrupados en dos bloques que se detallan a continuación. La invención concierne igualmente a los procedimientos de modulación y demodulación de señales según los procedimientos para Ia transmisión y recepción que se describen a continuación. Por supuesto, Ia invención también concierne a los dispositivos de emisión y/o de recepción de señales llevando a cabo dichos procedimientos.SUBSTITUTE SHEET (RULE 26) To achieve the above objectives, the invention provides modulation and demodulation devices, and more generally for the transmission and / or reception of signals using various procedures that can be grouped into two blocks detailed below. The invention also concerns the methods of modulation and demodulation of signals according to the procedures for transmission and reception described below. Of course, the invention also concerns the devices for transmitting and / or receiving signals by carrying out said procedures.
Procedimiento 1Procedure 1
En primer lugar, el procedimiento 1 de Ia invención se caracteriza por el diagrama de bloques del receptor que se muestra en Ia figura 11. Como transmisor, se emplea el banco de síntesis o sus correspondientes bloques duales de operaciones matriciales y de transformación y los filtros polifase/estructuras en celosía/etapas en mariposa, de manera se obtenga una característica de reconstrucción perfecta (Perfect Reconstruction - PR) o aproximarse a Ia misma (Near-Perfect Reconstruction N-PR). Es decir, el banco de filtros (análisis/síntesis) o los bloques de filtrado polifase/estructuras en celosía/estructuras en mariposa y de operaciones matriciales y de transformación del emisor y receptor conforman un bando de filtros (en configuración análisis/síntesis) o un transmultiplexador (en configuración síntesis/análisis) con características PR ó NPR. El bloque FEQ (Frequency domain Equalizer) es opcional, y permite Ia corrección de los efectos de un canal o medio de transmisión ubicado entre el transmisor y el receptor. La relación entre las señales de salida y Ia señal de entrada en el receptor se puede expresar comoIn the first place, the method 1 of the invention is characterized by the block diagram of the receiver shown in Figure 11. As a transmitter, the synthesis bank or its corresponding dual blocks of matrix and transformation operations and filters are used. polyphase / lattice structures / butterfly stages, so as to obtain a perfect reconstruction characteristic (Perfect Reconstruction - PR) or approach it (Near-Perfect Reconstruction N-PR). That is, the filter bank (analysis / synthesis) or the polyphase filtering blocks / lattice structures / butterfly structures and matrix operations and transformation of the transmitter and receiver form a filter side (in analysis / synthesis configuration) or a transmultiplexer (in synthesis / analysis configuration) with PR or NPR characteristics. The FEQ (Frequency domain Equalizer) block is optional, and allows the correction of the effects of a transmission channel or medium located between the transmitter and the receiver. The relationship between the output signals and the input signal in the receiver can be expressed as
X = Cn P^W 1 A 1 W y donde y : M datos de entrada al receptor. W : matriz DFT implementada mediante algoritmos rápidos y eficientes FFT.X = C n P ^ W 1 A 1 W and where y: M input data to the receiver. W: DFT matrix implemented by fast and efficient FFT algorithms.
Λ"1 : matriz diagonal.Λ "1 : diagonal matrix.
W"1 : matriz DFT inversa implementada mediante algoritmos rápidos y eficientes IFFT.W "1 : reverse DFT matrix implemented by fast and efficient IFFT algorithms.
Pra : matriz que caracteriza el filtrado polifase o las estructuras en celosía o en mariposa del receptor.P ra : matrix that characterizes the polyphase filtering or lattice or butterfly structures of the receiver.
HOJA DE SUSTITUCIÓN (REGLA 26) C^ : matriz que caracteriza el bloque de operaciones matriciales y de transformación del receptor.SUBSTITUTE SHEET (RULE 26) C ^: matrix that characterizes the block of matrix operations and transformation of the recipient.
X : datos de salida del receptor. Procedimiento 2 Otro procedimiento de esta invención también afecta a las estructuras del transmisor y del receptor. El diagrama de bloques del transmisor 2 se representa en Ia figura 12. La relación entre las señales de salida y de entrada del transmisor, se puede caracterizar del siguiente modo. y = w-' -pβ -ctt .χ dondeX: receiver output data. Procedure 2 Another method of this invention also affects the structures of the transmitter and receiver. The block diagram of the transmitter 2 is shown in Figure 12. The relationship between the output and input signals of the transmitter can be characterized as follows. y = w- '-p β -c tt .χ where
X : datos de entrada al transmisor.X: input data to the transmitter.
C1x : matriz que caracteriza el bloque de operaciones matriciales y de transformación del transmisor.C 1x : matrix that characterizes the block of matrix operations and transmitter transformation.
P1x : matriz que caracteriza el filtrado polifase o las estructuras en celosía o en mariposa del transmisor.P 1x : matrix that characterizes the polyphase filtering or lattice or butterfly structures of the transmitter.
W"1 : matriz DFT inversa implementada mediante algoritmos rápidos y eficientes IFFT. y : datos de salida del transmisor.W "1 : reverse DFT matrix implemented by fast and efficient IFFT algorithms. And: transmitter output data.
En Ia figura 13 se muestra el diagrama de bloques del receptor 2 que hay que utilizar de forma conjunta con el transmisor 2 de Ia figura 12. La relación entre las señales de salida y de entrada del receptor 2 se puede caracterizar del siguiente modo.Figure 13 shows the block diagram of the receiver 2 that must be used together with the transmitter 2 of Figure 12. The relationship between the output and input signals of the receiver 2 can be characterized as follows.
X = C11 -P^A-' - W -y donde y : datos de entrada al receptor. W : matriz DFT implementada mediante algoritmos rápidos y eficientes FFT.X = C 11 -P ^ A- '- W -y where y: input data to the receiver. W: DFT matrix implemented by fast and efficient FFT algorithms.
Λ"1 : matriz diagonal. Pn : matriz que caracteriza el filtrado polifase o las estructuras en celosía o en mariposa del receptor.Λ "1 : diagonal matrix. P n : matrix that characterizes the polyphase filtering or lattice or butterfly structures of the receiver.
Cn : matriz que caracteriza el bloque de operaciones matriciales y de transformación del receptor.C n : matrix that characterizes the matrix operations and transformation of the receiver block.
X : datos de salida del receptor.X: receiver output data.
HOJA DE SUSTITUCIÓN (REGLA 26) Transmisión con Prefijo CíclicoSUBSTITUTE SHEET (RULE 26) Transmission with Cyclic Prefix
La figura 14 muestra el diagrama de bloques de un sistema de comunicaciones que incluye el receptor-1 y Ia estrategia de prefijo cíclico. En ausencia de ruido, Ia relación entrada-salida sería:Figure 14 shows the block diagram of a communication system that includes the receiver-1 and the cyclic prefix strategy. In the absence of noise, the input-output ratio would be:
X = C^ - Vn W -1 Λ 1 W H Ya -C1x - X = Cn Yn Y1x -C1x XX = C ^ - V n W - 1 Λ 1 WHY at -C 1x - X = C n Y n Y 1x -C 1x X
La figura 15 muestra el diagrama de bloques de un sistema de comunicaciones que incluye el transmisor-2 y el receptor-2, empleando también Ia estrategia de prefijo cíclico. La relación entrada-salida sería:Figure 15 shows the block diagram of a communication system that includes transmitter-2 and receiver-2, also using the cyclic prefix strategy. The input-output ratio would be:
X = Cn Yn -A"1 W H W F1x C1x -X = Cn Yn Ya Ctt XX = C n Y n -A "1 WHWF 1x C 1x -X = C n Y n Y a C tt X
En ambos casos, se elige cada elemento del igualador FEQ de forma que se corrijan los efectos introducidos por el canal equivalente h [MuqO2, WanOO]. Si el banco de filtros del que se obtiene el transmultiplexador es de reconstrucción perfecta X = X , y en caso de ser de reconstrucción aproximada, X « X .In both cases, each element of the FEQ equalizer is chosen so that the effects introduced by the equivalent channel h [MuqO2, WanOO] are corrected. If the filter bank from which the transmultiplexer is obtained is of perfect reconstruction X = X, and if it is approximately reconstructed, X «X.
Transmisión con Rellenado de CerosTransmission with Zeros Filling
La figura 16 muestra el diagrama de bloques de un sistema de comunicaciones que incluye el receptor-1 y Ia estrategia de rellenado de ceros. En ausencia de ruido, Ia relación entrada-salida también sería: x=cB .pB .r1 .A-' .w.H-p ι -cs .χ=cB -p B .p, .c> "X Figure 16 shows the block diagram of a communications system that includes receiver-1 and the zero-fill strategy. In the absence of noise, the ratio input-output would also be: x = c B. p B. r 1 .A - ' . .H w - p ι c s = c B .χ - p B .p,. c > " X
La figura 17 muestra el diagrama de bloques de un sistema de comunicaciones que incluye el transmisor-2 y el receptor-2, empleando también Ia estrategia de rellenado de ceros. La relación entrada-salida de nuevo resultaría ser: X = Cn Yn Λ 1 W H W 1 Pα -C1x - X = Cn Yn Ya -C1x XFigure 17 shows the block diagram of a communication system that includes transmitter-2 and receiver-2, also employing the zero-fill strategy. The input-output ratio would again be: X = C n Y n Λ 1 WHW 1 P α -C 1x - X = C n Y n Y a -C 1x X
En ambos casos, se elige cada elemento del igualador FEQ de forma que se corrijan los efectos introducidos por el canal equivalente h [MuqO2, WanOO]. Si el banco de filtros del que se obtiene el transmultiplexador es de reconstrucción perfecta X = X , y en caso de ser de reconstrucción aproximada, X « X .In both cases, each element of the FEQ equalizer is chosen so that the effects introduced by the equivalent channel h [MuqO2, WanOO] are corrected. If the filter bank from which the transmultiplexer is obtained is of perfect reconstruction X = X, and if it is approximately reconstructed, X «X.
Características de las matrices C1x , Y1x , Cn y Yn .Characteristics of the matrices C 1x , Y 1x , C n and Y n .
Los procedimientos se basan en aprovechar las características que proporcionan los transmultiplexadores basados en bancos de filtros, y los moduladores multiportadoraThe procedures are based on taking advantage of the features provided by transmultiplexers based on filter banks, and multi-carrier modulators
HOJA DE SUSTITUCIÓN (REGLA 26) con DFT (implementada a través de algoritmos rápidos del tipo FFT), actuando conjuntamente con estrategias de prefijo cíclico y rellenado de ceros. Los transmultiplexadores basados en bancos de filtros, entre otras características, van a proporcionar una mayor separación espectral entre las subportadoras, Io que conlleva más inmunidad frente al ruido, incluidas las interferencias de banda estrecha de carácter impulsivo. Los moduladores multiportadora con DFT, junto con el prefijo o el rellenado de ceros, facilitan el proceso de igualación por subportadora en el dominio de Ia frecuencia.SUBSTITUTE SHEET (RULE 26) with DFT (implemented through fast FFT algorithms), acting in conjunction with cyclic prefix strategies and zero fill. Transmultiplexers based on filter banks, among other features, will provide greater spectral separation between subcarriers, which leads to more immunity against noise, including narrow-band interference of an impulsive nature. Multi-carrier modulators with DFT, together with the prefix or the filling of zeros, facilitate the subcarrier matching process in the frequency domain.
Las expresiones de las matrices Ctt , P1x , Cn y Pra vienen determinadas por los algoritmos rápidos de ejecución propios del banco de filtros en configuración de transmultiplexador que se esté utilizando. A su vez, los algoritmos rápidos provienen del modo de construir el banco de filtros de análisis (recepción) y del banco de filtros síntesis (transmisión) y de Ia longitud de los filtros.The expressions of the matrices C tt , P 1x , C n and P ra are determined by the fast execution algorithms of the filter bank in the transmultiplexer configuration being used. In turn, the fast algorithms come from the way of constructing the analysis filter bank (reception) and the synthesis filter bank (transmission) and from the length of the filters.
Una técnica conocida para el diseño de bancos de filtros o transmultiplexadores consiste en aplicar una modulación de tipo trigonométrica (coseno y/o seno habitualmente) a una función prototipo (filtro prototipo), que puede ser Ia misma función para análisis y para síntesis, o diferente (dos filtros prototipo). Los esquemas de modulación son muy numerosos, y son los que finalmente condicionan las características del denominada "Bloque de Operaciones Matriciales y de Transformación". Algunos ejemplos ilustrativos y no limitativos de tipos de modulación pueden ser los siguientes: a) Modulación cosenoA known technique for the design of filter banks or transmultiplexers is to apply a trigonometric modulation (cosine and / or sinus usually) to a prototype function (prototype filter), which can be the same function for analysis and synthesis, or different (two prototype filters). The modulation schemes are very numerous, and they are the ones that finally condition the characteristics of the so-called "Matrix Operations and Transformation Block". Some illustrative and non-limiting examples of modulation types may be the following: a) Cosine modulation
Figure imgf000014_0001
donde 0 < / < (M-l) , / [«] son los filtros que conforman el banco de síntesis o de transmisión ( Ft [z) ), h, [n\ son los filtros que conforman el banco de análisis o de recepción ( H, (z) ), px \n\ y p2 [n] son los filtros prototipo, kx y k2 son constantes, 0, son parámetros que controlan Ia modulación coseno.
Figure imgf000014_0001
where 0 </ <(Ml), / [«] are the filters that make up the synthesis or transmission bank (F t [z)), h, [n \ are the filters that make up the analysis or reception bank (H, (z)), p x \ n \ yp 2 [n] are the prototype filters, k x and k 2 are constants, 0, are parameters that control the cosine modulation.
HOJA DE SUSTITUCIÓN (REGLA 26) b) Modulación senoSUBSTITUTE SHEET (RULE 26) b) Sine modulation
Figure imgf000015_0001
donde 0</< (M-I)1
Figure imgf000015_0002
son los filtros que conforman el banco de síntesis o de transmisión (F1^z)), ht[n] son los filtros que conforman el banco de análisis o de recepción
Figure imgf000015_0003
son los filtros prototipo, kx y k2 son constantes, O1 son parámetros que controlan Ia modulación coseno. c) Modulación mixta para un sistema de 2M subportadoras [Lin95]
Figure imgf000015_0001
where 0 </ <(MI) 1
Figure imgf000015_0002
are the filters that make up the synthesis or transmission bank (F 1 ^ z)), h t [n] are the filters that make up the analysis or reception bank
Figure imgf000015_0003
are the prototype filters, k x and k 2 are constant, or 1 are parameters that control the cosine modulation. c) Mixed modulation for a 2M subcarrier system [Lin95]
/?,[«] = £,•/?, [n] -eos T7'z'n ' ι = 0, i = M/ ? , [«] = £, • / ? , [n] -eos T7 ' z ' n 'ι = 0, i = M
H1[H]^k1- px[n\ casi — -i-n I, l≤ι≤(M-l)H 1 [H] ^ k 1 - p x [n \ almost - -in I, l≤ι≤ (Ml)
\M J\ M J
h,[n]
Figure imgf000015_0004
h, [n]
Figure imgf000015_0004
Z1[H] = H1[N + M -n], O≤i≤M f¡[n] = ti,[N + M-n], l≤i≤(M-l) donde f,[n] y f,'[n\ son los filtros que conforman el banco de síntesis o de transmisión ( F1 (z) ), H1 [n] y U1 [n] son los filtros que conforman el banco de análisis o de recepción (H1 (z)), px [n] es el filtro prototipo, kx y k2 son constantes.Z 1 [H] = H 1 [N + M -n], O≤i≤M f¡ [n] = ti, [N + Mn], l≤i≤ (Ml) where f, [n] and f, ' [n \ are the filters that make up the synthesis or transmission bank (F 1 (z)), H 1 [n] and U 1 [n] are the filters that make up the analysis or reception bank (H 1 (z)), p x [n] is the prototype filter, k x and k 2 are constants.
Por tanto, en esta invención se lleva a cabo un planteamiento general que ya de por sí es un cuadro de descripción que aporta ventajas, y que a su vez ofrece numerosas posibilidades de explotación en función de los bancos de filtros o transmultiplexadores sobre los que se sustentan. Partiendo de Ia descripción general y empleando otras modulaciones coseno y/o seno presentadas en [Aka92, Mal92, Koi92, Vai93, Fli94, Lin95, Aka96, Str96, MitO1, DinO2, FarO3a, FarO3b, CruO4, Vio04, LinO6], o en cualquier otro sitio de las que se deduzcan algoritmos rápidos con un bloque de filtrado polifase o de estructuras en celosía o en mariposa, y otro bloque de operaciones matriciales y de transformación, agrupables como se detalla en esta invención, pueden formar parte de-Ios procedimientos de Ia invención propuestos.Therefore, in this invention a general approach is carried out which is already a description box that provides advantages, and which in turn offers numerous exploitation possibilities depending on the banks of filters or transmultiplexers on which sustain Starting from the general description and using other cosine and / or sine modulations presented in [Aka92, Mal92, Koi92, Vai93, Fli94, Lin95, Aka96, Str96, MitO1, DinO2, FarO3a, FarO3b, CruO4, Vio04, LinO6], or in Any other site from which fast algorithms are deduced with a block of polyphase filtering or lattice or butterfly structures, and another block of matrix and transformation operations, grouped as detailed in this invention, can be part of the procedures. of the proposed invention.
HOJA DE SUSTITUCIÓN (REGLA 26) Las especificaciones del filtro prototipo dependen de Ia aplicación particular para Ia que se utilice el procedimiento de Ia invención, y Ia longitud del filtro prototipo también condiciona el bloque de operaciones matriciales y de transformación. A modo de ejemplo ilustrativo no limitativo, se puede deducir que para Ia modulación coseno mostrada en esta subsección en el epígrafe "a", el algoritmo rápido es diferente en función de si Ia longitud del filtro prototipo es N=2KM ó Λ/=(2K+1 )/W, siendo K un número entero y M el número de canales, y también es diferente para el caso de que K sea un número par o impar (para más detalle de este ejemplo concreto, consultar [Koi 92, Vai93, MitO1 , Vio04, CruO4]).SUBSTITUTE SHEET (RULE 26) The specifications of the prototype filter depend on the particular application for which the method of the invention is used, and the length of the prototype filter also determines the matrix and transformation operations block. By way of illustrative, non-limiting example, it can be deduced that for the cosine modulation shown in this subsection in section "a", the fast algorithm is different depending on whether the length of the prototype filter is N = 2KM or Λ / = ( 2K + 1) / W, where K is an integer and M is the number of channels, and it is also different in the case that K is an even or odd number (for more details on this specific example, see [Koi 92, Vai93 , MitO1, Vio04, CruO4]).
El bloque de filtrado polifase consiste en una serie de filtros en paralelo. Los coeficientes que caracterizan a dichos filtros se obtienen a partir de un filtro prototipo de distintas formas [Cro83, Vai93, FIÍ94, MitO1 , DinO2]. A su vez, se pueden implementar en forma directa, transversal, recursiva, en celosía, o agrupadas por parejas, tal y como se ha indicado, y no son excluidas en los procedimientos propuestos. A modo de ejemplo ilustrativo no limitativo, si P(z) es Ia función del sistema del filtro prototipo, Ia descomposición en M filtros polifase tipo 1 G1 (zM ) sería
Figure imgf000016_0001
GAz)
Figure imgf000016_0002
p[n-M +
Figure imgf000016_0003
para 0 ≤ ¿ ≤ M -l.The polyphase filter block consists of a series of filters in parallel. The coefficients that characterize these filters are obtained from a prototype filter of different shapes [Cro83, Vai93, FIÍ94, MitO1, DinO2]. In turn, they can be implemented directly, transversely, recursively, in lattice, or grouped in pairs, as indicated, and are not excluded in the proposed procedures. By way of illustrative non-limiting example, if P (z) is the function of the prototype filter system, the decomposition into M type 1 G 1 (z M ) polyphase filters would be
Figure imgf000016_0001
GA z )
Figure imgf000016_0002
p [nM +
Figure imgf000016_0003
for 0 ≤ ¿≤ M -l.
El bloque de estructuras en mariposa se conecta habitualmente en cascada. Un ejemplo ilustrativo no limitativo es el diagrama de bloques de Ia figura 4.The butterfly structure block is usually cascaded. An illustrative non-limiting example is the block diagram of Figure 4.
DESCRIPCIÓN DE LAS FIGURASDESCRIPTION OF THE FIGURES
Figura 1. Diagrama de bloques de las etapas de (a) transmisión y de (b) recepción para MCM. Figura 2. Diagrama de bloques de una implementación de los convertidoresFigure 1. Block diagram of the stages of (a) transmission and (b) reception for MCM. Figure 2. Block diagram of an implementation of the converters
Paralelo/Serie y Serie/Paralelo. Figura 3. Diagrama de bloques de un transmultiplexador basado en un banco de filtros de diezmado máximo. Figura 4. Diagrama de bloques de un receptor o banco de síntesis empleando algoritmos rápidos.Parallel / Series and Series / Parallel. Figure 3. Block diagram of a transmultiplexer based on a bank of maximum decimated filters. Figure 4. Block diagram of a receiver or synthesis bank using fast algorithms.
HOJA DE SUSTITUCIÓN (REGLA 26) Figura 5. Diagrama de bloques de un transmisor empleando algoritmos rápidos.SUBSTITUTE SHEET (RULE 26) Figure 5. Block diagram of a transmitter using fast algorithms.
Figura 6. Diagrama de bloques de un receptor empleando algoritmos rápidos.Figure 6. Block diagram of a receiver using fast algorithms.
Figura 7. Diagrama de bloques general de un transmisor con bancos de filtros empleando algoritmos rápidos. Figura 8. Diagrama de bloques general de un receptor con bancos de filtros empleando algoritmos rápidos. Figura 9. Diagrama de bloques de un sistemas de comunicaciones que emplea modulación multiportadora y prefijo cíclico.Figure 7. General block diagram of a transmitter with filter banks using fast algorithms. Figure 8. General block diagram of a receiver with filter banks using fast algorithms. Figure 9. Block diagram of a communication system that uses multi-carrier modulation and cyclic prefix.
Figura 10. Diagrama de bloques de un sistemas de comunicaciones que emplea modulación multiportadora y rellenado de ceros.Figure 10. Block diagram of a communications system that uses multi-carrier modulation and zero fill.
Figura 11. Diagrama de bloques (a) directo y (b) con algoritmos rápidos del receptor-1. Figura 12. Diagrama de bloques (a) directo y (b) con algoritmos rápidos del transmisorFigure 11. Block diagram (a) direct and (b) with fast algorithms of receiver-1. Figure 12. Block diagram (a) direct and (b) with fast transmitter algorithms
2.2.
Figura 13. Diagrama de bloques (a) directo y (b) con algoritmos rápidos del receptor-2. Figura 14. Diagrama de bloques de un sistemas de comunicaciones que emplea el receptor-1 y prefijo cíclico. Figura 15. Diagrama de bloques de un sistema de comunicaciones que emplea el transmisor-2 y el receptor-2, junto con prefijo cíclico.Figure 13. Block diagram (a) direct and (b) with fast algorithms of receiver-2. Figure 14. Block diagram of a communication system using the receiver-1 and cyclic prefix. Figure 15. Block diagram of a communication system that uses transmitter-2 and receiver-2, together with cyclic prefix.
Figura 16. Diagrama de bloques de un sistemas de comunicaciones que emplea el receptor-1 y rellenado de ceros.Figure 16. Block diagram of a communication system that uses receiver-1 and zero-fill.
Figura 17. Diagrama de bloques de un sistemas de comunicaciones que emplea el transmisor-2 y el receptor-2, junto con rellenado de ceros. Figura 18. Diagrama de bloques de un ejemplo de transmisor-1. Figura 19. Diagrama de bloques de un ejemplo de receptor-1. Figura 20. Módulo de Ia respuesta en frecuencia en determinados subcanales del banco DFT. Figura 21. Módulo de Ia respuesta en frecuencia en determinados subcanales del sistema propuesto en el ejemplo del procedimiento 1. Figura 22. Diagrama de bloques de un ejemplo de transmisor-2. Figura 23. Diagrama de bloques de un ejemplo de receptor-2.Figure 17. Block diagram of a communications system that uses transmitter-2 and receiver-2, along with zero-fill. Figure 18. Block diagram of an example of transmitter-1. Figure 19. Block diagram of an example of receiver-1. Figure 20. Module of the frequency response in certain subchannels of the DFT bank. Figure 21. Module of the frequency response in certain subchannels of the system proposed in the example of procedure 1. Figure 22. Block diagram of an example of transmitter-2. Figure 23. Block diagram of an example of receiver-2.
Figura 24. Módulo de Ia respuesta en frecuencia en determinados subcanales del sistema propuesto en el ejemplo del procedimiento 2.Figure 24. Module of the frequency response in certain subchannels of the system proposed in the example of procedure 2.
HOJA DE SUSTITUCIÓN (REGLA 26) DESCRIPCIÓN DE EJEMPLOS DE REALIZACIÓN DE LA INVENCIÓNSUBSTITUTE SHEET (RULE 26) DESCRIPTION OF EXAMPLES OF EMBODIMENT OF THE INVENTION
Los procedimientos descritos en esta invención suponen un incremento de Ia robustez del sistema, Io que trae consigo el aumento de fiabilidad en canales ruidosos, o Ia disminución de Ia potencia de emisión de Ia señal a transmitir, Io que implica menor consumo de energía, mayor duración de las baterías, y/o Ia disminución del tamaño del dispositivo receptor, entre otras ventajas. Por supuesto que estos ejemplos son ilustrativos no limitativos.The procedures described in this invention imply an increase in the robustness of the system, which brings with it the increase in reliability in noisy channels, or the decrease in the emission power of the signal to be transmitted, which implies less energy consumption, greater battery life, and / or the decrease in the size of the receiving device, among other advantages. Of course, these examples are illustrative, not limiting.
Ejemplo de Procedimiento 1 y prefijo cíclico En las figuras 18 y 19 se muestran respectivamente los diagramas de bloques de un transmisor y un receptor concreto empleando el procedimiento 1 de Ia invención. En dichas figuras no se representan ni el bloque de inclusión de prefijo cíclico, ni el de selección las muestras oportunas en el receptor.Example of Procedure 1 and cyclic prefix Figures 18 and 19 show respectively the block diagrams of a transmitter and a specific receiver using the method 1 of the invention. In these figures, neither the cyclic prefix inclusion block nor the selection of the appropriate samples in the receiver are represented.
El transmultiplexador que sirve como base del diseño se obtiene a partir de un banco de filtros de diezmado máximo cercano a Ia reconstrucción perfecta (NPR), con estructura en paralelo, de 64 canales, donde los filtros de recepción -I) ) y de transmisión (fk [n] , 0 ≤ k ≤ (M -I) ) se obtienen a partir
Figure imgf000018_0001
de un filtro prototipo
Figure imgf000018_0002
, empleando las siguientes expresiones:The transmultiplexer that serves as the basis of the design is obtained from a maximum decimated filter bank near the perfect reconstruction (NPR), with a 64-channel parallel structure, where the reception filters -I)) and transmission (f k [n], 0 ≤ k ≤ (M -I)) are obtained from
Figure imgf000018_0001
of a prototype filter
Figure imgf000018_0002
, using the following expressions:
Figure imgf000018_0003
Figure imgf000018_0003
El filtro prototipo utilizado tiene longitud Λ/=768. Para esta longitud, puesto que satisface Ia relación N=2KM, siendo K un número par, ei bloque de operaciones matriciales y de transformación del receptor viene dado por
Figure imgf000018_0004
obtenido de Ia matriz de modulación cuyos elementos vienen dados por
Figure imgf000018_0005
The prototype filter used has length Λ / = 768. For this length, since it satisfies the relation N = 2KM, being K an even number, the block of matrix operations and transformation of the receiver is given by
Figure imgf000018_0004
obtained from the modulation matrix whose elements are given by
Figure imgf000018_0005
La notación es similar a [Koi92, Vai93, CruO4]), y significaThe notation is similar to [Koi92, Vai93, CruO4]), and means
C : transformada discreta del coseno, tipo IV, realizada mediante algoritmos eficientes.C: discrete cosine transform, type IV, performed by efficient algorithms.
Λc : matriz diagonal MxM que implica multiplicar cada rama por un valor constante.Λ c : diagonal matrix MxM that implies multiplying each branch by a constant value.
HOJA DE SUSTITUCIÓN (REGLA 26) I : matriz identidad. J : matriz antidiagonal, definida comoSUBSTITUTE SHEET (RULE 26) I: identity matrix. J: antidiagonal matrix, defined as
Figure imgf000019_0001
Figure imgf000019_0001
Así mismo, para este banco cercano a Ia reconstrucción perfecta (NPR) se utilizan filtros polifase cuya matriz de filtrado es diagonal y viene caracterizada porLikewise, for this bank near the perfect reconstruction (NPR), polyphase filters are used whose filtering matrix is diagonal and is characterized by
Figure imgf000019_0002
Figure imgf000019_0002
Los filtros de transmisión son versiones reflejadas temporalmente de los filtros de recepción, y Ia matriz de transmisión se obtiene a partir deThe transmission filters are temporarily reflected versions of the reception filters, and the transmission matrix is obtained from
' r Cs/r ?™ i
Figure imgf000019_0003
de forma que el algoritmo eficiente también se expresa en función de una transformada discreta del coseno, tipo IV, realizada mediante algoritmos eficientes, una matriz diagonal MxM que implica multiplicar cada rama por un valor constante, las matrices I y J , y una matriz diagonal con las componentes polifase.'r Cs / r? ™ i
Figure imgf000019_0003
so that the efficient algorithm is also expressed based on a discrete transform of the cosine, type IV, performed by efficient algorithms, a diagonal matrix MxM that implies multiplying each branch by a constant value, the matrices I and J, and a diagonal matrix with the polyphase components.
Con anterioridad se comentaba que los procedimientos 1 y 2 propuestos presentan unas muy buenas características de separación espectral entre subportadoras. Para mostrarlo, en Ia figura 20 se representa el módulo de Ia respuesta en frecuencia de algunas subbandas del banco de filtros que se obtiene de Ia DFT (el estandarizado), con una atenuación con máximos de unos 13.5 dBs en cada subcanal. En Ia figura 21 , se representa el módulo de Ia respuesta de algunas subbandas del banco de filtros adicional añadido en el procedimiento propuesto. Se aprecian atenuaciones de más de 90 dBs por subcanal.Previously, it was commented that the proposed procedures 1 and 2 have very good characteristics of spectral separation between subcarriers. To show it, Figure 20 shows the module of the frequency response of some subbands of the filter bank that is obtained from the DFT (the standardized one), with an attenuation with maximums of about 13.5 dBs in each subchannel. In Figure 21, the module of the response of some subbands of the additional filter bank added in the proposed procedure is shown. Attenuations of more than 90 dBs per subchannel are appreciated.
Ejemplo de Procedimiento 2 y prefijo cíclico En las figuras 22 y 23 se muestran respectivamente los diagramas de bloques de un transmisor y un receptor concreto empleando el procedimiento 2 de Ia invención. En dichas figuras no se representan ni el bloque de inclusión de prefijo cíclico, ni el de selección las muestras oportunas en el receptor.Example of Procedure 2 and cyclic prefix Figures 22 and 23 respectively show the block diagrams of a transmitter and a specific receiver using the method 2 of the invention. In these figures, neither the cyclic prefix inclusion block nor the selection of the appropriate samples in the receiver are represented.
HOJA DE SUSTITUCIÓN (REGLA 26) El transmultiplexador que sirve como base del diseño se obtiene también a partir de un banco de filtros de diezmado máximo cercano a Ia reconstrucción perfecta (NPR)1 con estructura en paralelo, de 64 canales, donde los filtros de recepción (hk [n] , 0 ≤ k ≤ (M -\) ) y de transmisión (fk [n],0 ≤ k ≤ (M -I) ) se obtienen como se han indicado con anterioridad. El filtro prototipo p[n] utilizado tiene longitud Λ/=832.SUBSTITUTE SHEET (RULE 26) The transmultiplexer that serves as the basis of the design is also obtained from a bank of maximum decimated filters near the perfect reconstruction (NPR) 1 with a parallel structure, of 64 channels, where the reception filters (h k [n] , 0 ≤ k ≤ (M - \)) and transmission (f k [n], 0 ≤ k ≤ (M -I)) are obtained as indicated above. The prototype filter p [n] used has length Λ / = 832.
Para esta longitud, puesto que satisface Ia relación Λ/=(2K+1)/W, siendo K un número par, el bloque de operaciones matriciales y de transformación del receptor viene dado por (Ia notación es similar a Ia indicada con anterioridad y a Ia que aparece en [CruO4]):
Figure imgf000020_0001
For this length, since it satisfies the ratio Λ / = (2K + 1) / W, being K an even number, the block of matrix operations and transformation of the receiver is given by (The notation is similar to the one indicated above and The one that appears in [CruO4]):
Figure imgf000020_0001
Los filtros de transmisión también son versiones reflejadas temporalmente de los filtros de recepción, y Ia matriz de transmisión se obtiene igualmente a partir deThe transmission filters are also temporarily reflected versions of the reception filters, and the transmission matrix is also obtained from
c« í2r+iw = 2 - cos U + - — " -(-1) — -c «í2r + iw = 2 - cos U + - -" - (- 1 ) - -
de forma que el algoritmo eficiente también se expresa en función de una transformada discreta del coseno, tipo IV, realizada mediante algoritmos eficientes, una matriz diagonal MxM que implica multiplicar cada rama por un valor constante, las matrices I y J , y una matriz diagonal con las componentes polifase.so that the efficient algorithm is also expressed in terms of a discrete transform of the cosine, type IV, performed by efficient algorithms, a diagonal matrix MxM that implies multiplying each branch by a constant value, the matrices I and J, and a diagonal matrix with the polyphase components.
Finalmente, en Ia figura 24 se representa el módulo de Ia respuesta de algunas subbandas del banco de filtros adicional añadido en el procedimiento propuesto. Se aprecian atenuaciones de casi 100 dBs por subcanal.Finally, Figure 24 shows the module of the response of some subbands of the additional filter bank added in the proposed procedure. Attenuations of almost 100 dBs per subchannel are appreciated.
HOJA DE SUSTITUCIÓN (REGLA 26) SUBSTITUTE SHEET (RULE 26)

Claims

REIVINDICACIONES
1.- Procedimiento de transmisión y recepción de una señal multiportadora, que comprende Ia generación de las secuencias que se transmiten a través de una serie de subsistemas y/o un canal o medio de transmisión, estando este canal determinado por el enlace desde un equipo transmisor hasta el receptor; se caracteriza porque comprende: En el Transmisor1. Procedure for transmitting and receiving a multi-carrier signal, which comprises the generation of the sequences that are transmitted through a series of subsystems and / or a transmission channel or means, this channel being determined by the link from a device transmitter to receiver; It is characterized in that it comprises: In the Transmitter
- etapa de procesamiento de las señales de entrada subportadoras a través de un algoritmo rápido obtenido a partir de un banco de filtros de síntesis donde cada uno de los filtros se ha obtenido mediante una modulación trigonométrica de coseno, seno, o mixta aplicada a un filtro prototipo. Este procesamiento comprende operaciones matriciales y de transformación del tipo transformada discreta del coseno y/o del seno y filtrado. Opcionalmente, realización de una transformada de Fourier discreta inversa, IFFT, a los datos obtenidos tras el banco de síntesis.- processing stage of the subcarrier input signals through a fast algorithm obtained from a bank of synthesis filters where each of the filters has been obtained by means of a trigonometric modulation of cosine, sine, or mixed applied to a filter prototype. This processing includes matrix and transformation operations of the discrete transformed type of cosine and / or sinus and filtering. Optionally, realization of an inverse discrete Fourier transform, IFFT, to the data obtained after the synthesis bank.
- Conversión Paralelo/Serie En el Receptor- Parallel / Serial Conversion On Receiver
Conversión Serie/ParaleloSerial / Parallel Conversion
Realización de una transformada de Fourier discreta (FFT), a los datos obtenidos tras Ia conversión serie paralelo.Realization of a discrete Fourier transform (FFT), to the data obtained after the parallel serial conversion.
Igualador FEQ, cuyos coeficientes se pueden obtener para corregir los efectos de distorsión del canal equivalente que caracteriza el enlace entre el transmisor y el receptor. Si no se ha realizado en el Transmisor, realización de una transformada de Fourier discreta inversa (IFFT), a los datos obtenidos tras el igualador.FEQ equalizer, whose coefficients can be obtained to correct the distortion effects of the equivalent channel that characterizes the link between the transmitter and the receiver. If it has not been done in the Transmitter, realization of a reverse discrete Fourier transform (IFFT), to the data obtained after the equalizer.
Procesar las señales a través de un algoritmo rápido obtenido a partir de un banco de filtros de análisis donde cada uno de los filtros se ha obtenido mediante una modulación trigonométrica coseno, seno, o mixta aplicada a un filtro prototipo. El banco de filtros de análisis está relacionado con el del transmisor-1 porque ambos bancos de filtros, de forma conjunta y aislada, presentan Ia característica de reconstrucción perfecta o de proximidad a Ia reconstrucción perfecta, al igual que si forman una estructura de transmultiplexador. Este procesamiento comprende operaciones matriciales y de transformación del tipo transformada discreta del coseno y/o del seno y filtrado.Process the signals through a fast algorithm obtained from a bank of analysis filters where each of the filters has been obtained by means of a cosine, sine, or mixed trigonometric modulation applied to a prototype filter. The analysis filter bank is related to that of the transmitter-1 because both filter banks, together and in isolation, have the characteristic of perfect reconstruction or proximity to the perfect reconstruction, just as if they form a transmultiplexer structure. This processing includes matrix and transformation operations of the discrete transformed type of cosine and / or sinus and filtering.
HOJA DE SUSTITUCIÓN (REGLA 26) SUBSTITUTE SHEET (RULE 26)
2.- Procedimiento de transmisión y recepción de una señal multiportadora, que comprende Ia generación de las secuencias que se transmiten a través de una serie de subsistemas y/o un canal o medio de transmisión, estando este canal determinado por el enlace desde un equipo transmisor hasta el receptor; se caracteriza porque comprende:2.- Procedure of transmission and reception of a multi-carrier signal, which comprises the generation of the sequences that are transmitted through a series of subsystems and / or a transmission channel or means, this channel being determined by the link from a device transmitter to receiver; It is characterized because it comprises:
En el TransmisorIn the transmitter
- etapa de procesamiento de las señales de entrada subportadoras a través de un algoritmo rápido obtenido a partir de un banco de filtros de síntesis donde cada uno de los filtros se ha obtenido mediante una modulación trigonométrica de coseno, seno, o mixta aplicada a un filtro prototipo. Este procesamiento comprende operaciones matriciales y de transformación del tipo transformada discreta del coseno y/o del seno y filtrado polifase, donde el bloque de filtrado.- processing stage of the subcarrier input signals through a fast algorithm obtained from a bank of synthesis filters where each of the filters has been obtained by means of a trigonometric modulation of cosine, sine, or mixed applied to a filter prototype. This processing includes matrix and transformation operations of the discrete transformed type of cosine and / or sinus and polyphase filtering, where the filtering block.
Opcionalmente, realización de una transformada de Fourier discreta FFT, a los datos obtenidos tras el banco de síntesis.Optionally, carrying out a FFT discrete Fourier transform, to the data obtained after the synthesis bank.
Conversión Paralelo/Serie En el-ReceptorParallel / Serial Conversion at Receiver
Conversión Serie/ParaleloSerial / Parallel Conversion
-( Realización de una transformada de Fourier discreta inversa (IFFT), a los datos obtenidos tras Ia conversión serie paralelo.- ( Performing a reverse discrete Fourier transform (IFFT), to the data obtained after the parallel serial conversion.
Igualador FEQ, cuyos coeficientes se pueden obtener para corregir los efectos de distorsión del canal equivalente que caracteriza el enlace entre el transmisor y el receptor.FEQ equalizer, whose coefficients can be obtained to correct the distortion effects of the equivalent channel that characterizes the link between the transmitter and the receiver.
V Si no se ha realizado en el Transmisor, realización de una transformada de Fourier discreta (FFT), a los datos obtenidos tras el igualador.V If it has not been carried out in the Transmitter, carrying out a discrete Fourier transform (FFT), to the data obtained after the equalizer.
Procesar las señales a través de un algoritmo rápido obtenido a partir de un banco de filtros de análisis donde cada uno de los filtros se ha obtenido mediante una modulación trigonométrica de coseno, seno, o mixta aplicada a un filtro prototipo. El banco de filtros de análisis está relacionado con el del transmisor-1 porque ambos bancos de filtros, de forma conjunta y aislada, presentan Ia característica de reconstrucción perfecta o de proximidad a Ia reconstrucción perfecta, al igual que si forman una estructura de transmultiplexador. Este procesamiento comprende operaciones matriciales y de transformación del tipo transformada discreta del coseno y/o del seno y filtrado.Process the signals through a fast algorithm obtained from a bank of analysis filters where each of the filters has been obtained through a trigonometric modulation of cosine, sine, or mixed applied to a prototype filter. The analysis filter bank is related to that of the transmitter-1 because both filter banks, together and in isolation, have the characteristic of perfect reconstruction or proximity to the perfect reconstruction, just as if they form a transmultiplexer structure. This processing includes matrix and transformation operations of the discrete transformed type of cosine and / or sinus and filtering.
HOJA DE SUSTITUCIÓN (REGLA 26) SUBSTITUTE SHEET (RULE 26)
3.- Procedimiento de transmisión y recepción de una señal multiportadora según cualquiera de las reivindicaciones anteriores donde Ia modulación trigonométrica es una de las siguientes: a) Modulación coseno3. Procedure for transmitting and receiving a multi-carrier signal according to any of the preceding claims wherein the trigonometric modulation is one of the following: a) Cosine modulation
Figure imgf000023_0001
donde 0</<(M-l) siendo M el número de portadoras,
Figure imgf000023_0002
son los filtros que conforman el banco de síntesis o de transmisión (F1 (z)), Λ,[«] son los filtros que
Figure imgf000023_0001
where 0 </ <(Ml) where M is the number of carriers,
Figure imgf000023_0002
are the filters that make up the synthesis or transmission bank (F 1 (z)), Λ, [«] are the filters that
" conforman el banco de análisis o de recepción (H1 (z)),
Figure imgf000023_0003
y p2\n\ son los filtros prototipo, kx y k2 son constantes, θt son parámetros constantes que controlan Ia modulación coseno. b) Modulación seno " make up the analysis or reception bank (H 1 (z)),
Figure imgf000023_0003
and p 2 \ n \ are the prototype filters, k x and k 2 are constant, θ t are constant parameters that control the cosine modulation. b) Sine modulation
Figure imgf000023_0004
donde 0</<(M-l) siendo M el número de portadoras, f,\n\ son los filtros que conforman el banco de síntesis o de transmisión
Figure imgf000023_0005
son los filtros que conforman el banco de análisis o de recepción (H1 (z)), px
Figure imgf000023_0006
son los filtros prototipo, kλ y k2 son constantes, O1 son parámetros constantes que controlan Ia modulación coseno. c) Modulación mixta para un sistema de 2M subportadoras
Figure imgf000023_0004
where 0 </ <(Ml) where M is the number of carriers, f, \ n \ are the filters that make up the synthesis or transmission bank
Figure imgf000023_0005
are the filters that make up the analysis or reception bank (H 1 (z)), p x
Figure imgf000023_0006
are the prototype filters, k λ and k 2 are constant, or 1 are constant parameters that control the cosine modulation. c) Mixed modulation for a 2M subcarrier system
ht [H] = £,•#[«] -eos T7-/'n > i = 0,/ = Afh t [H] = £, • # [«] -eos T7 - / ' n > i = 0, / = Af
hXn] = k 2 ' P\ [»]-cos —•/•« , 1</<(M-1)
Figure imgf000023_0007
f,[n] = h,[N + M-n], O≤i≤MhX n ] = k 2 'P \ [»] -cos - • / • «, 1 </ <(M-1)
Figure imgf000023_0007
f, [n] = h, [N + Mn], O≤i≤M
HOJA DE SUSTITUCIÓN (REGLA 26) f¡ [n] = h, [N + M-n] , 1 < / < (M-1) donde / [«] y f¡ [n] son los filtros que conforman el banco de síntesis o de transmisión ( F1 (z) ), H1 [«] y H1 [«] son los filtros que conforman el banco de análisis o de recepción ( H, (z) ), px [n] es el filtro prototipo, kλ y k2 son constantes.SUBSTITUTE SHEET (RULE 26) f¡ [n] = h, [N + Mn], 1 </ <(M-1) where / [«] and f¡ [n] are the filters that make up the synthesis or transmission bank (F 1 (z )), H 1 [«] and H 1 [«] are the filters that make up the analysis or reception bank (H, (z)), p x [n] is the prototype filter, k λ and k 2 are constant .
4. Procedimiento de transmisión y recepción según cualquiera de las reivindicaciones anteriores de una señal multiportadora donde el filtrado en transmisión y recepción es un filtrado en mariposa, en celosía o un filtrado polifase, donde el bloque de filtrado polifase consiste en una serie de filtros en paralelo, independientes o agrupados por parejas, cuyos coeficientes se obtienen a partir de un filtro prototipo.4. A transmission and reception method according to any one of the preceding claims of a multi-carrier signal where the transmission and reception filtering is a butterfly, lattice or polyphase filtering, wherein the polyphase filtering block consists of a series of filters in parallel, independent or grouped in pairs, whose coefficients are obtained from a prototype filter.
5.- Procedimiento de transmisión y recepción de una señal multiportadora según una cualquiera de las reivindicaciones 1-4, caracterizado porque emplea junto al convertidor paralelo serie del transmisor un bloque de adición de un prefijo o sufijo, y junto al convertidor serie/paralelo de recepción, un bloque de selección de las muestras correspondientes y válidas de Ia transmisión, descartando las no válidas.5. Procedure for transmitting and receiving a multi-carrier signal according to any one of claims 1-4, characterized in that it uses a block to add a prefix or suffix together with the serial parallel converter, and together with the serial / parallel converter reception, a block of selection of the corresponding and valid samples of the transmission, discarding the invalid ones.
6.- Procedimiento de transmisión y recepción de una señal multiportadora según una cualquiera de las reivindicaciones 1-4, caracterizado porque además de los bloques incluidos en dichas reivindaciones, emplea junto al convertidor paralelo/serie del transmisor un bloque de adición de ceros, y tras el convertidor serie/paralelo de recepción, un bloque de solapamiento y suma que permite diagonalizar el canal matricial discreto equivalente utilizando matrices DFTs.6. Procedure for transmitting and receiving a multi-carrier signal according to any one of claims 1-4, characterized in that in addition to the blocks included in said claims, a zero-addition block is used together with the parallel / serial converter of the transmitter, and after the serial / parallel reception converter, an overlap and sum block that allows the equivalent discrete matrix channel to be diagonalized using DFTs matrices.
7.- Procedimiento de transmisión y recepción de una señal multiportadora según una cualquiera de las reivindicaciones anteriores, caracterizado porque además de los bloques incluidos en dichas reivindaciones, emplea una etapa de aplicación de un retardo de duración predeterminada z-(7M+"o) donde T es un número entero, y 0 < n0 < M siendo M el número de portadoras, a los símbolos modulados entregados por el transmisor7. Procedure for transmitting and receiving a multi-carrier signal according to any one of the preceding claims, characterized in that in addition to the blocks included in said claims, it employs a step of applying a predetermined duration delay z- (7M + "o) where T is an integer, and 0 <n 0 <M where M is the number of carriers, to the modulated symbols delivered by the transmitter
8.- Procedimiento de transmisión y recepción de una señal multiportadora según una cualquiera de las reivindicaciones 1-6, caracterizado porque Ia matriz de componentes8. Procedure for transmitting and receiving a multi-carrier signal according to any one of claims 1-6, characterized in that the component matrix
HOJA DE SUSTITUCIÓN (REGLA 26) polifase, de estructuras en celosía o de estructuras en mariposa del receptor se encuentra multiplicada por un retardo, de Ia forma
Figure imgf000025_0001
donde T es un número entero, y 0 < n0 < M siendo M el número de portadoras, en Ia que Ia implementación de dicho retardo se lleva a cabo antes del receptor o incluido en una de sus etapas.SUBSTITUTE SHEET (RULE 26) polyphase, lattice structures or butterfly structures of the receiver is multiplied by a delay, of the form
Figure imgf000025_0001
where T is an integer, and 0 <n 0 <M being M the number of carriers, in which the implementation of said delay is carried out before the receiver or included in one of its stages.
9.- Procedimiento de transmisión y recepción de una señal multiportadora según una cualquiera de las reivindicaciones anteriores, caracterizado porque Ia señal multiportadora es una señal multiportadora multiplexada por división en frecuencia asociada a portadoras moduladas de forma síncrona y/o asincrona.9. Procedure for transmitting and receiving a multi-carrier signal according to any one of the preceding claims, characterized in that the multi-carrier signal is a multi-carrier signal multiplexed by frequency division associated to carriers synchronously and / or asynchronously modulated.
10.- Sistema de transmisión y recepción de una señal multiportadora caracterizado por incluir los medios necesarios para realizar las etapas del procedimiento descrito en cualquiera de las reivindicaciones 1-9.10. Transmission and reception system of a multi-carrier signal characterized by including the necessary means to perform the steps of the procedure described in any of claims 1-9.
HOJA DE SUSTITUCIÓN (REGLA 26) SUBSTITUTE SHEET (RULE 26)
PCT/ES2009/000295 2008-06-04 2009-05-28 Method for the transmission (modulation) and reception (demodulation) of signals in communication systems with dft-based multicarrier modulation and transmultiplexers based on sine and/or cosine modulated filter banks, and transmitting and receiving devices WO2009147259A2 (en)

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