Patent EP0668679A2 successfully refreshed from Google Patents.
EP0668679A2
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EP
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OFDM system
Assignee: Italtel SpA
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Filing: 1995-02-15
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Granted: —
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Expires: 2015-02-15
Abstract
Abstract Orthogonal frequency division multiplexing system and method (OFDM) for the transmission N of data sequences or channels (so - SN - 1 ) at a predetermined rate F, consisting of a transmsitter, an intermediate transmission mean and a receiver. The transmitter includes a rate converter (LMRC) having N inputs and I outputs, where N=M.I, with M and I integer, producing at output I channels (ao, a 1 , a 2 , .. a I-1 ) at a rare F1 higher than F, a processor (I-DFT) able to perform the discrete Fourier transform on the I channels, a first plurality of multitone modulators (A o , A 1 , A 2 , .. A I-1 ) supplied by a first carrier, polyphase filters (Q o (f), Q i (f), Q I-1 -(f)) connected to the multitone modulator of said first plurality and a second plurality of multitone modulators (B o , B 1 , B 2 , .. B I - 1 ), connected to polyphase filters and supplied by a second carrier. The receiver has a dual structure.
Inventors
- 👤 Gianfranco Cariolaro
- 👤 Giovanni Castagna
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 18:19
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/26; H04L27/2601; H04L27/2626; H04L27/2627; H04L27/2628; H04L27/263; H04L27/2631
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
303 words
Orthogonal frequency division multiplexing system (OFDM) for the transmission of N sequences or channels of data c n (t) at a predetermined rate F , consisting of a transmitter including: - data staggering means (DS) receiving said sequences c n (t) at input; - pre-modulation and ordering means (P&O) connected to the outputs of said data staggering means (DS); and - multiplexing means (SC); - parallel series conversion means (P/S) connected to the outputs of said multiplexing means (SC), characterized by the fact that said multiplexing means (SC) include: - a first rate converter (LMRC), having N inputs and I outputs, where N = M.I, with integer M and I, producing at output I channels (a o . a 1 , a 2 , .. a l - 1 ) at a rate F 1 higher than F; - a first processor (I-DFT) which inputs are connected to the outputs of said first rate converter (LMRC), and performing the discrete Fourier transform on I channels; - a first plurality of multitone modulators (A o , A 1 , A 2 , .. A I-1 ), each one connected to an output of said first processor (I-DFT), and receiving on the other input a carrier: where β M (n) is the remainder of the integer division of n by M and W N =exp (j2π/N) ; - a first plurality of polyphase filters (Q o (f), Q ; (f), Q I-1 (f)) each one connected to the output of a corresponding multitone modulator of said first plurality (B); - a second plurality of multitone modulators (B o , B i , B 2 , .. B I - 1 ), each one connected to the output of the corresponding polyphase filter of said first plurality Q(f) and receiving on the other input a carrier:
Claim 2
Dependent Claim
303 words
Orthogonal frequency division multiplexing system (OFDM) for the transmission of N sequences or channels of data c n (t) at a predetermined rate F , consisting of a transmitter including: - data staggering means (DS) receiving said sequences c n (t) at input; - pre-modulation and ordering means (P&O) connected to the outputs of said data staggering means (DS); and - multiplexing means (SC); - parallel series conversion means (P/S) connected to the outputs of said multiplexing means (SC), characterized by the fact that said multiplexing means (SC) include: - a first rate converter (LMRC), having N inputs and I outputs, where N = M.I, with integer M and I, producing at output I channels (a o . a 1 , a 2 , .. a l - 1 ) at a rate F 1 higher than F; - a first processor (I-DFT) which inputs are connected to the outputs of said first rate converter (LMRC), and performing the discrete Fourier transform on I channels; - a first plurality of multitone modulators (A o , A 1 , A 2 , .. A I-1 ), each one connected to an output of said first processor (I-DFT), and receiving on the other input a carrier: where β M (n) is the remainder of the integer division of n by M and W N =exp (j2π/N) ; - a first plurality of polyphase filters (Q o (f), Q ; (f), Q I-1 (f)) each one connected to the output of a corresponding multitone modulator of said first plurality (B); - a second plurality of multitone modulators (B o , B i , B 2 , .. B I - 1 ), each one connected to the output of the corresponding polyphase filter of said first plurality Q(f) and receiving on the other input a carrier:
Claim 3
Dependent Claim
278 words
System with orthogonal frequency division multiplexing (OFDM) according to claim 1, characterized by the fact that the receiver includes: - parallel-serial conversion means (S/P) receiving at input the signal emitted by the transmitter; - demultiplexing means (CS) including: a) a third plurality of multitone modulators (MTM) each one connected to one of the I outputs of said serial-parallel conversion means (S/P), and receiving on the other input a carrier: b) a second plurality of polyphase filters Q i (f) R , each one connected to the output of the corresponding modulator of said third plurality of multitone modulators (MTM1); c) a fourth plurality of modulators (MTM2), each one connected to the output of a corresponding filter of said second plurality of polyphase filters Q i (f) R , and receiving on the other input a carrier: where β M (n) is the remainder of the integer division of n by M and W N =exp (j2π/N) ; d) a second processor (DFT) which inputs are connected to the outputs of multitone modulators (MTM) of the fourth plurality, and performing the reverse discrete Fourier transform on I channels; e) a second rate converter (MLRC), having I inputs and N outputs, where N = M.I, with M and I integer, producing at output N channels (so, S 1 , S2 , .. SN - 1 ) at a rate F lower than F 1 ; - demodulation and ordering means (D&O) connected to the outputs of said demultiplexing means (CS); - means (DDSK) for re-alignment of data they receive at input the outputs of demodulation and ordering means (D&O) and emitting at output data sequences (so - S 2N-1 ).
Claim 4
Dependent Claim
238 words
Orthogonal frequency division multiplexing method (OFDM) for the transmission of N data (c n (t)) sequences or channels having a predetermined rate F, said method including the following steps: a - to submit said sequences (c n (t)) to data staggering (DS) b - to pre-modulate and to order (P&O) the sequences so treated (x n (t)); c - to multiplex (SC) the pre-modulated and ordered sequences (s n (t)); d - to convert said sequences (s n (t)) into the serial form (P/S); characterized by the fact to foresee also the following steps: b1 - to convert (LMRC) said N pre-modulated and ordered sequences (s n (t)) in I channels (ao, a 1 , a 2 , .. a I-1 ) having a rate F1 higher than said set rate F, where N = M.!; b2 - to perform the discrete Fourier transform (I-DFT) on I channels (ao, a 1 , a 2 , .. a I-1 ); b3 - to modulate each one of the I channels where the Fourier transform has been made with a carrier: where β M (n) is the remainder of the integer division of n by M and W N =exp (j2π/N) ; b4 - to filter (Q i (f)) said modulated I channels; b5 - to modulate each one of the I filtered channels (B o , B i , B 2 , .. B I-1 ) with a carrier:
Claim 5
Dependent Claim
238 words
Orthogonal frequency division multiplexing method (OFDM) for the transmission of N data (c n (t)) sequences or channels having a predetermined rate F, said method including the following steps: a - to submit said sequences (c n (t)) to data staggering (DS) b - to pre-modulate and to order (P&O) the sequences so treated (x n (t)); c - to multiplex (SC) the pre-modulated and ordered sequences (s n (t)); d - to convert said sequences (s n (t)) into the serial form (P/S); characterized by the fact to foresee also the following steps: b1 - to convert (LMRC) said N pre-modulated and ordered sequences (s n (t)) in I channels (ao, a 1 , a 2 , .. a I-1 ) having a rate F1 higher than said set rate F, where N = M.!; b2 - to perform the discrete Fourier transform (I-DFT) on I channels (ao, a 1 , a 2 , .. a I-1 ); b3 - to modulate each one of the I channels where the Fourier transform has been made with a carrier: where β M (n) is the remainder of the integer division of n by M and W N =exp (j2π/N) ; b4 - to filter (Q i (f)) said modulated I channels; b5 - to modulate each one of the I filtered channels (B o , B i , B 2 , .. B I-1 ) with a carrier:
Claim 6
Dependent Claim
210 words
Method for orthogonal frequency division demultiplexing method (OFDM) of a multiplexed signal, according to claim 1, characterized by the fact to foresee the following steps: - to convert (S/P) the serial signal ( VR (t O )) received into I parallel channels, having a transmission rate F1 higher than the said predetermined rate F; - to demodulate (MTM) each one of the I parallel channels with a carrier: - to filter (Q i (f) R ) I channels so demodulated; - additionally to demodulate (MTM) the I filtered channels with a carrier: where β M (n) is the remainder of the integer division of n by M and W N =exp (j2π/N) ; - to make the reverse discrete Fourier transform (I-DFT) on the I demodulated channels; - to convert (MLRC) the I channels submitted to Fourier transform into N channels (so, S 1 , s 2 , ... S N-1 ) having a rate F lower than the transmission rate F1 and equal to the said predetermined rate, where N = M.I; - to demodulate and to order (D&O) the N channels at said predetermined rate F and re-align (DDSK) data so ordered to obtain the sequences of data transmitted in origin (so - s 2n - 1 ).
References Cited (Backward Citations)
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