Adaptive self-quieter suppression for OFDM wireless communication systems
View Patent ↗Various embodiments to provide cancellation techniques that can be used to address the self-quieter problem are described. For example, a receiver that includes a tone selector and a self-quieter suppressor is provided. The tone selector ( 202 ) determines and selects a self-quieter corrupted tone from a frequency domain signal that exhibits a self-quieter. The self-quieter suppressor ( 203 ) determines an initial phase, an angular speed and an amplitude estimate for the frequency domain self-quieter. The suppressor then generates a reconstructed frequency domain self-quieter using the initial phase, the angular speed and the amplitude estimate and subtracts the reconstructed frequency domain self-quieter from the corrupted tone to produce a self-quieter suppressed tone to replace the corrupted tone. Such an approach can realize a significant reduction in processing and complexity, as compared to known alternatives, making it an attractive and cost-effective solution for dealing with the self-quieter problem.
1. A method for adaptive self-quieter suppression comprising:
selecting a self-quieter corrupted tone from a frequency domain signal that exhibits a self-quieter;
determining an initial phase, an angular speed and an amplitude estimate for the self-quieter in the frequency domain;
determining a phase change rate over a time division duplex (TDD) frame interval;
determining a current initial phase of a current TDD frame by searching a finite number of values of the initial phase;
determining an intermediate phase that is a difference between the current initial phase and the phase change rate times a number of past TDD frames;
applying a low-pass filter to the intermediate phase to reduce variation;
determining the initial phase for the frequency domain self-quieter by summing the low-pass filtered intermediate phase and the phase change rate times the number of past TDD frames;
generating a reconstructed frequency domain self-quieter using the initial phase, the angular speed and the amplitude estimate; and
replacing the self-quieter corrupted tone by a self-quieter suppressed tone, wherein the self-quieter suppressed tone is the self-quieter corrupted tone minus the reconstructed frequency domain self-quieter.
2. The method of claim 1 , wherein the angular speed is determined based on a known self-quieter frequency, a known OFDM system carrier frequency and a known OFDM symbol interval.
3. The method of claim 1 , wherein determining the amplitude estimate of the frequency domain self-quieter comprises
determining the amplitude estimate based on an average power difference between the corrupted tone and a neighbor tone of the corrupted tone and
applying a low-pass filter to reduce variation.
4. The method of claim 1 , further comprises
selecting at least one additional self-quieter corrupted tone from the frequency domain signal in addition to the self-quieter corrupted tone.
5. A receiver comprising:
a tone selector adapted to determine a self-quieter corrupted tone from a frequency domain signal that exhibits a self-quieter;
a self-quieter suppressor
adapted to determine an initial phase, an angular speed and an amplitude estimate for the frequency domain self-quieter,
adapted to determine a phase change rate over a time division duplex (TDD) frame interval,
adapted to determine a current initial phase of a current TDD frame by searching a finite number of values of the initial phase,
adapted to determine an intermediate phase that is a difference between the current initial phase and the phase change rate times a number of past TDD frames,
adapted to apply a low-pass filter to the intermediate phase to reduce variation, and
adapted to determine the initial phase for the frequency domain self-quieter by summing the low-pass filtered intermediate phase and the phase change rate times the number of past TDD frames,
adapted to generate a reconstructed frequency domain self-quieter using the initial phase, the angular speed and the amplitude estimate, and
adapted to subtract the reconstructed frequency domain self-quieter from the corrupted tone to produce a self-quieter suppressed tone to replace the corrupted tone.
6. The receiver of claim 5 , wherein the self-quieter suppressor is further adapted to determine the angular speed based on a known self-quieter frequency, a known OFDM system carrier frequency and a known OFDM symbol interval.
7. The receiver of claim 5 , wherein the self-quieter suppressor is further
adapted to determine the amplitude estimate based on an average power difference between the corrupted tone and a neighbor tone of the corrupted tone and
adapted to apply a low-pass filter to reduce variation.
8. The receiver of claim 5 , wherein the self-quieter suppressor is further
adapted to select at least one additional self-quieter corrupted tone from the frequency domain signal in addition to the self-quieter corrupted tone.