Clipping distortion canceller for OFDM signals
OwnerHangjun Chen, Alexander M. Haimovichinventors
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Abstract
Methods and apparatus are provided for reducing clipping noise from an OFDM signal, the methods and apparatus are operable to carry out actions including: (a) transforming a received orthogonal frequency division multiplexed (OFDM) signal from a transmission channel into the frequency domain, the OFDM signal having been subject to a clipping function prior to transmission in order to reduce the peak-to-average power ratio (PAPR); (b) recovering data symbols from the transformed OFDM signal, which include clipping noise; (c) estimating the clipping noise in the frequency domain based on the data symbols; and (d) subtracting the estimated clipping noise from the transformed OFDM signal.
Claims28
A method, comprising:
- (a) transforming a received orthogonal frequency division multiplexed (OFDM) signal from a transmission channel into the frequency domain, the OFDM signal having been subject to a clipping function prior to transmission in order to reduce the peak-to-average power ratio (PAPR);
- (b) recovering data symbols from the transformed OFDM signal, which include clipping noise;
- (c) subjecting the data symbols to substantially the same clipping function to which the OFDM signal had been subject to prior to transmission to produce clipped data symbols;
- (d) attenuating the data symbols;
- (e) subtracting the attenuated data symbols from the clipped data symbols to estimate the clipping noise in the frequency domain based on the data symbols;
- and
- (f) subtracting the estimated clipping noise from the transformed OFDM signal.
An apparatus, comprising:
- a receiver operable to receive an orthogonal frequency division multiplexed (OFDM) signal from a transmission channel, the OFDM signal having been subject to a clipping function prior to transmission in order to reduce the peak-to-average power ratio (PAPR);
- a frequency transform unit operable to transform the OFDM signal to the frequency domain;
- a decoding unit operable to recover data symbols from the frequency domain OFDM signal, which include clipping noise;
- a noise estimator operable to estimate the clipping noise in the frequency domain based on the data symbols to produce clipped data symbols;
- an attenuator circuit operable to attenuate the data symbols;
- a first difference circuit operable to subtract the attenuated data symbols from the clipped data symbols to estimate the clipping noise in the frequency domain based on the data symbols;
- and
- a second difference circuit operable to subtract the estimated clipping noise from the transformed OFDM signal.
An apparatus including a processor operating under the control of one or more software programs that cause the processor to carry out actions, comprising:
- (a) transforming a received orthogonal frequency division multiplexed (OFDM) signal from a transmission channel into the frequency domain, the OFDM signal having been subject to a clipping function prior to transmission in order to reduce the peak-to-average power ratio (PAPR);
- (b) recovering data symbols from the transformed OFDM signal, which include clipping noise;
- (c) subjecting the data symbols to substantially the same clipping function to which the OFDM signal had been subject to prior to transmission to produce clipped data symbols;
- (d) attenuating the data symbols;
- (e) subtracting the attenuated data symbols from the clipped data symbols to estimate the clipping noise in the frequency domain based on the data symbols;
- and
- (f) subtracting the estimated clipping noise from the transformed OFDM signal.
A storage medium containing one or more software programs that are operable to cause a processor executing the one or more software programs to carry out actions, comprising:
- (a) transforming a received orthogonal frequency division multiplexed (OFDM) signal from a transmission channel into the frequency domain, the OFDM signal having been subject to a clipping function prior to transmission in order to reduce the peak-to-average power ratio (PAPR);
- (b) recovering data symbols from the transformed OFDM signal, which include clipping noise;
- (c) subjecting the data symbols to substantially the same clipping function to which the OFDM signal had been subject to prior to transmission to produce clipped data symbols;
- (d) attenuating the data symbols;
- (e) subtracting the attenuated data symbols from the clipped data symbols to estimate the clipping noise in the frequency domain based on the data symbols;
- and
- (f) subtracting the estimated clipping noise from the transformed OFDM signal.
Dependencies are inferred from the claim text.