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US 2001/0040869 A1Published application
Transmission of OFDM signals
OwnerPeter Neil Mossinventor
Life of this patent
Estimating the term…
Abstract
In an OFDM transmitter, the input signal is modified in several different ways by sign switches (22) operating on sub-bands generated by a splitter (20). An inverse fast Fourier transform circuit (14) generates an output for each of all the possible types of modification producing a plurality of candidate signals. The signal of best quality is selected by subjecting the candidate signals to processing in a model (54) representing the transmitter amplifier (16), and estimating the candidate signal of best quality determined by a clip energy estimator (58) and/or a low-level estimator (60). A control circuit (64) then causes the transmitter to transmit the candidate signal of best quality together with signalling information indicating the corresponding setting of the sign switches (22).
Claims10
An OFDM transmitter comprising:
- an input for receiving an input signal for transmission as an OFDM signal;
- modifying means coupled to the input for modifying the input signal in a plurality of different predefined ways so as to generate from the input signal a plurality of different candidate signals for possible transmission as an OFDM signal;
- inverse fast Fourier transform means coupled to the modifying means to transform each of the candidate signals into OFDM form;
- transmitter amplifier means coupled to the output of the inverse fast Fourier transform means for transmitting a selected one of the candidate signals in OFDM form;
- estimating means coupled to the output of the inverse fast Fourier transform means for subjecting the OFDM-form candidate signals to processing corresponding to that which is applied by the transmitter amplifier means and for estimating the quality of the transmitted signal for each of the candidate signals;
- selecting means for selecting one of the candidate signals which provides good estimated quality and for causing the transmitter to transmit through the transmitter amplifier means the selected candidate signal as the output OFDM signal;
- and
- means for transmitting with the selected candidate signal signalling information indicating the form of modification which is applied by the modifying means to produce the selected candidate signal.
5 more elements
An OFDM transmission system comprising an OFDM transmitter and an OFDM receiver, the OFDM transmitter comprising:
- an input for receiving an input signal for transmission as an OFDM signal;
- modifying means coupled to the input for modifying the input signal in a plurality of different predefined ways so as to generate from the input signal a plurality of different candidate signals for possible transmission as an OFDM signal;
- inverse fast Fourier transform means coupled to the modifying means to transform each of the candidate signals into OFDM form;
- transmitter amplifier means coupled to the output of the inverse fast Fourier transform means for transmitting a selected one of the candidate signals in OFDM form;
- estimating means coupled to the output of the inverse fast Fourier transform means for subjecting the OFDM-form candidate signals to processing corresponding to that which is applied by the transmitter amplifier means and for estimating the quality of the transmitted signal for each of the candidate signals;
- selecting means for selecting one of the candidate signals which provides good estimated quality and for causing the transmitter to transmit through the transmitter amplifier means the selected candidate signal as the output OFDM signal;
- and
- means for transmitting with the selected candidate signal signalling information indicating the form of modification which is applied by the modifying means to produce the selected candidate signal;
- and the OFDM receiver comprising:
- receiving means for receiving the transmitted candidate signal and the signalling information;
- fast Fourier transform means coupled to the receiving means to transform the received signal back from OFDM form;
- modifying means coupled to the output of the fast Fourier transform means to modify the signal output from the fast Fourier transform means;
- and
- control means for receiving the signalling information and causing the modifying means to modify the signal output from the fast Fourier transform means in dependence thereon so as to reverse the modification reflected by the modifying means in the OFDM transmitter.
11 more elements
A method of transmitting an OFDM signal, comprising the steps of:
- receiving an input signal for transmission as an OFDM signal;
- modifying the input signal in a plurality of different predefined ways so as to generate from the input signal a plurality of different candidate signals for possible transmission as an OFDM signal;
- transforming each of the candidate signals into OFDM form;
- transmitting a selected one of the candidate signals in OFDM form;
- subjecting the OFDM-form candidate signals to processing corresponding to that which is applied by the transmitter amplifier means and estimating the quality of the transmitted signal for each of the candidate signals;
- selecting one of the candidate signals which provides good estimated quality and transmitting the selected candidate signal as the output OFDM signal;
- and
- transmitting with the selected candidate signal signalling information indicating the form of modification which is applied by the modifying means to produce the selected candidate signal.
5 more elements
A method of transmitting an OFDM signal, comprising the steps of, at an OFDM transmitter;
- receiving an input signal for transmission as an OFDM signal;
- modifying the input signal in a plurality of different predefined ways so as to generate from the input signal a plurality of different candidate signals for possible transmission as an OFDM signal;
- transforming each of the candidate signals into OFDM form;
- transmitting a selected one of the candidate signals in OFDM form;
- subjecting the OFDM-form candidate signals to processing corresponding to that which is applied by the transmitter amplifier means and estimating the quality of the transmitted signal for each of the candidate signals;
- selecting one of the candidate signals which provides good estimated quality and transmitting the selected candidate signal as the output OFDM signal;
- and
- transmitting with the selected candidate signal signalling information indicating the form of modification which is applied by the modifying means to produce the selected candidate signal;
- and at an OFDM receiver:
- receiving the transmitted candidate signal and the signalling information;
- transforming the received signal back from OFDM form;
- modifying the signal output from the fast Fourier transform means;
- and
- receiving the signalling information and causing the modifying means to modify the transformed back signal in dependence thereon so as to reverse the modification introduced in the OFDM transmitter.
11 more elements
Dependencies are inferred from the claim text.