Selective filtering for co-channel interference reduction
AssigneeNorthern Telecom Limited
InventorsWen Tong, Rui Wang
Life of this patent
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Abstract
Complex signal samples of an input signal are supplied to via a frequency down-shifter to a digital filter, and to a time-frequency transform unit which produces a plurality of frequency components each associated with a respective frequency band within a bandwidth of the input signal. The frequency component having the maximum momentary energy is determined to determine the down-shifting frequency for the associated frequency band to be filtered, and to determine a complementary up-shifting following the digital filter to produce an output signal. The filter can be a bandpass filter or a bandstop filter, especially for reducing co-channel interference in different types of wireless communications systems.
Claims20
A selective filter comprising:
- a time-frequency transform unit responsive to samples of an input signal to be filtered for producing a plurality of frequency components of the signal;
- an identification unit for providing an output identifying a maximum energy one of the frequency components;
- and
- a filter for filtering the input signal to produce an output signal, the filter being responsive to the output of the identification unit to provide a pass or stop band, associated with the identified one of the frequency components, within a larger bandwidth of the input signal.
A selective filter comprising:
- a transform unit responsive to complex signal samples of an input signal to be filtered for producing a plurality of frequency components of the signal, each of said frequency components being associated with a respective one of a like plurality of frequency bands within a bandwidth of the input signal;
- a maximum energy determination unit responsive to the plurality of frequency components for determining which of said frequency components has a greatest momentary energy;
- and
- a digital filter for filtering the complex signal samples of the input signal with a filter pass or stop band corresponding to the frequency band associated with the frequency component determined by the maximum energy determination unit to have the greatest momentary energy.
A method of selectively filtering an input signal, comprising the steps of:
- performing a time-frequency transform of complex signal samples representing the input signal to produce a plurality of frequency components;
- determining which of the plurality of frequency components has the greatest momentary energy;
- and
- filtering the input signal using a respective one of a plurality of filter pass or stop bands within the bandwidth of the input signal and selected in accordance with the determination of which of the plurality of frequency components has the greatest momentary energy.
Dependencies are inferred from the claim text.