Amplitude attenuation estimation and recovery systems for OFDM signal used in communication systems

1. An apparatus comprising:

one or more antennae configured to receive an OFDM signal;

a radio frequency end tuner to receive the OFDM signal from the antennae;

an amplitude attenuation estimation module that performs amplitude correction on the received OFDM signals; and

a DFT filter bank, wherein the amplitude correction is corrected in frequency domain by estimating a main vector component and error vector components of at least two adjacent points of the main vector component and applying the correction for adjacent carriers in order to avoid leakage in the DFT filter bank.

2. The apparatus of claim 1 , wherein the amplitude attenuation estimation module comprises a detector to determine if the amplitude correction is based on one signal distortion or multi-signal distortion.

3. The apparatus of claim 1 , wherein the amplitude attenuation estimation module comprises a Hilbert-Huang Transform (HHT) module.

4. The apparatus of claim 1 further comprising an automatic gain control unit, wherein the amplitude attenuation estimation module corrects amplitude attenuation contributed by the automatic gain control unit.

5. In a device receiving OFDM signals, the device comprising:

a circuit comprised of:

a radio frequency end tuner that outputs one or more baseband signals, wherein the signals are comprised of samples;

a memory to store the samples;

an amplitude information module that calculates estimated amplitude distortion for the samples;

a segmenting module that segments the samples into groups, wherein the groups are averaged;

a curve fitting module that interpolates the averaged samples, to account for the number of samples in the original baseband signals;

an inverter that inverses the samples from the curve fitting module; and

one or more multipliers that multiply samples from the one or more baseband signals with samples from the curve fitting module.

6. The device of claim 5 , wherein the radio frequency end tuner provides a baseband signal with an in-phase component, and a baseband signal with a quadrature component.

7. The device of claim 5 , wherein the amplitude information module implements one of the following: time-domain estimator, frequency-domain estimator, signal envelope detector, or deterministic information.

8. The device of claim 5 , wherein the segmenting module implements a sliding window, wherein each window includes a number of samples.

9. The device of claim 5 , wherein the curve fitting module accounts for samples for one of the following systems: a 2K system, a 4K system, or an 8K system.

10. The device of claim 5 , wherein the samples are one of the following: a 2K system, a 4K system, or an 8K system.

11. The device of claim 5 further comprising a fading detector to determine whether the signals are based on one-signal distortion or multi-signal distortion.

12. The device of claim 5 further comprising a Fast Fourier Transform module that receives signals from the multipliers, and a property/finite alphabet module that receives output signal from the Fast Fourier Transform module, and processes the signal based on the constellation information or FA property.

13. A method comprising:

receiving an OFDM signal in the form of a transmitted RF signal;

outputting one or more baseband signals based on the received OFDM signal;

converting the one or more baseband signals to digital signals comprised of samples;

calculating amplitude values of the digital signals;

obtaining an envelope of amplitude distortion based on the amplitude values;

multiplying inverses of samples of the envelope of amplitude distortion with the received OFDM signal to produce corrected signals;

determining whether to implement amplitude correction based on a threshold in a fading estimator and in an amplitude envelope estimator;

providing the corrected signals to a Fast Fourier Transform module to derive a discrete Fourier transform and an inverse; and

processing an output signal from the Fast Fourier Transform module based on constellation information of the OFDM signal.

14. The method of claim 13 , wherein the method is implemented for Doppler compensation in regards to inter carrier interference cancellation.

15. The method of claim 13 , wherein the obtaining of an envelope of amplitude distortion is known a priori.

16. The method of claim 15 , wherein the method is performed for at least one of the following: an RF amplifier; an IF amplifier; and a baseband AGC unit.

17. The method of claim 13 further comprising considering phase/time offset in the obtaining the envelope of amplitude distortion.