Radio receiver
DC CAFCFirst Claim
1. A method comprising:
- over-sampling, at a desired frequency, a passband of received signals to create a bit stream, wherein the received signals include signals of interest and interference generating signals, the interference generating signals capable of generating intermodulation products inband of the signals of interest;
isolating signals of interest in the bit stream using one or more decimating filters;
isolating source signals that generate one or more intermodulation products inband of the signal of interest using one or more decimating filters;
computing an estimate of each of the one or more intermodulation products from the source signals that generate the one or more intermodulation products;
cancelling out one or more inband intermodulation products using the estimate of the intermodulation products; and
performing phase and amplitude adjustment on estimations of the intermodulation product interfering signals in a closed loop manner, wherein performing phase and amplitude adjustment of the estimations comprises performing sub-sample phase shifts to make a phase adjustment on the estimations of the intermodulation product interfering signals.
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Abstract
Various apparatuses and methods are described to reduce interference in signals subject to intermodulation products and high power narrow band interfering signals on lower power wideband signals. Apparatuses and methods described herein also provide the capability for supporting multi-standards, multi-modes and multi-bands in wireless and wired applications with a single receiver or a receiver with minor variations. The receiver described herein samples the entire band in which there can be signals of interest or signals that can generate interference. All of these signals are sampled in one bit stream and the bit stream is processed to isolate signals of interest and interfering signals. The isolated interfering signals are then cancelled out of the signals of interest.
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Citations
52 Claims
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1. A method comprising:
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over-sampling, at a desired frequency, a passband of received signals to create a bit stream, wherein the received signals include signals of interest and interference generating signals, the interference generating signals capable of generating intermodulation products inband of the signals of interest; isolating signals of interest in the bit stream using one or more decimating filters; isolating source signals that generate one or more intermodulation products inband of the signal of interest using one or more decimating filters; computing an estimate of each of the one or more intermodulation products from the source signals that generate the one or more intermodulation products; cancelling out one or more inband intermodulation products using the estimate of the intermodulation products; and performing phase and amplitude adjustment on estimations of the intermodulation product interfering signals in a closed loop manner, wherein performing phase and amplitude adjustment of the estimations comprises performing sub-sample phase shifts to make a phase adjustment on the estimations of the intermodulation product interfering signals.
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2. An apparatus comprising:
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means for over-sampling, at a desired frequency, a passband of received signals to create a bit stream, wherein the received signals include signals of interest and interference generating signals, the interference generating signals capable of generating intermodulation products inband of the signals of interest; means for isolating signals of interest in the bit stream using one or more decimating filters; means for isolating source signals that generate one or more intermodulation products inband of the signal of interest using one or more decimating filters; means for computing an estimate of each of the one or more intermodulation products from the source signals that generate the one or more intermodulation products; means for canceling out one or more inband intermodulation products using the estimate of the intermodulation products; and means for performing phase and amplitude adjustment on estimations of the intermodulation product interfering signals in a closed loop manner, wherein the means for performing phase and amplitude adjustment of the estimations comprises means for performing sub-sample phase shifts to make a phase adjustment on the estimations of the intermodulation product interfering signals.
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3. An apparatus comprising:
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a sampling unit to sample, at a desired frequency, a passband of received signals to create a bit stream, wherein the received signals include signals of interest and interference generating signals, the interference generating signals capable of generating intermodulation products inband of the signals of interest; one or more filters to isolate signals of interest and interfering signals in the bit stream; a cancellation unit to cancel out isolated interference generated signals using estimations of the intermodulation products generated by the isolated interfering signals, wherein the estimations of the isolated interfering signals comprise estimations of intermodulation products falling inband of the signals of interest; and a phase and amplitude adjuster to adjust the phase and amplitude of estimations of the isolated interfering signals in a closed loop manner, wherein the phase and amplitude adjuster performs phase and amplitude adjustment of the estimations by making sub-sample phase shifts to make a phase adjustment on the estimations of the isolated interfering signals.
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4. A method comprising:
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outputting a pair of identical digital samples from a sigma delta analog to digital converter (ADC) after sampling an intermediate frequency signal with the sigma delta ADC; applying a first decimating filter to one of the pair to perform a bandpass operation to obtain a signal of interest with in-band interference intermodulation products, wherein the first decimating filter comprises a finite impulse response (FIR) filter; applying a second decimating filter to the other pair to perform a band reject operation for the signal of interest to create out of band signals that are a source of the in-band interference intermodulation products, wherein the second decimating filter comprises a FIR filter; generating an estimate of in-band intermodulation interference based on the out of band signals; and adding an inverted version of the estimate of in-band intermodulation interference to the signal of interest having the in-band interference intermodulation products to cancel interference caused thereby and create a resulting signal, wherein the first and second FIR filters are applied at a rate at which the sigma delta ADC is applied.
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5. A method comprising:
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outputting a pair of identical digital samples from a sigma delta analog to digital converter (ADC) after sampling an intermediate frequency signal with the sigma delta ADC; applying a first decimating filter to one of the pair to perform a bandpass operation to obtain a signal of interest with in-band interference intermodulation products; applying a second decimating filter to the other pair to perform a band reject operation for the signal of interest to create out of band signals that are a source of the in-band interference intermodulation products; generating an estimate of in-band intermodulation interference based on the out of band signals, wherein generating an estimate of in-band interference is based on second and third order input intercept points (IIP2 and IIP3); and adding an inverted version of the estimate of in-band intermodulation interference to the signal of interest having the in-band interference intermodulation products to cancel interference caused thereby and create a resulting signal. - View Dependent Claims (6, 7)
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8. further A method comprising:
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outputting a pair of identical digital samples from a sigma delta analog to digital converter (ADC) after sampling an intermediate frequency signal with the sigma delta ADC; applying a first decimating filter to one of the pair to perform a bandpass operation to obtain a signal of interest with in-band interference intermodulation products; applying a second decimating filter to the other pair to perform a band reject operation for the signal of interest to create out of band signals that are a source of the in-band interference intermodulation products; generating an estimate of in-band intermodulation interference based on the out of band signals; adding an inverted version of the estimate of in-band intermodulation interference to the signal of interest having the in-band interference intermodulation products to cancel interference caused thereby and create a resulting signal; and
cross-correlating the resulting signal with the estimate of the in-band interference. - View Dependent Claims (9, 10, 11, 12)
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13. An apparatus comprising:
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a converter to generate a pair of identical bit streams, wherein the bit stream comprises a flash analog to digital converter (ADC) 4 bit low resolution bit stream used to search the receive band for source signals and generate the estimates of the intermodulation products; at least one decimating filter coupled to the converter to filter the bit streams from an intermediate frequency (IF) signal prior to application of a digital down conversion, wherein the IF filter reduces out of band blocking signals prior to converter; a lowpass filter coupled to the decimating filter to filter the digital samples output from the decimating filter; an in-band interference compensation unit coupled to the lowpass filter; and a second module to pass the frequency bands with source signals to a filter function, wherein the low resolution bit stream from the flash ADC is narrow-band filtered to isolate the source signals with fairly wide filters. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. A method comprising:
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receiving a signal comprising a signal of interest and one or more source signals; generating a sampled data stream by oversampling the received signal over a receiver bandwidth at a low resolution; recovering one or more of the source signals from the sampled data stream; using a digital process to estimate an intermodulation product in real time using the one or more recovered source signals; generating an intermodulation cancellation signal in real time from the estimate of the intermodulation product; and using the intermodulation cancellation signal to cancel the intermodulation product in a bandwidth of the signal of interest. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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41. A receiver comprising:
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a sampling rate multiplier to sample an analog signal using an oversampling ratio; a first finite impulse response (FIR) filter to pass a bandwidth of a signal of interest; a second FIR filter to reject the bandwidth of the signal of interest; a first downsampler to downsample a first signal to a sampling frequency; a second downsampler to downsample a second signal to the sampling frequency; and an intermodulation compensator, wherein; the first FIR filter is coupled to the sampling rate multiplier and to the first downsampler; the second FIR filter is coupled to the sampling rate multiplier and to the second downsampler; and the first and second downsamplers are coupled to the intermodulation compensator. - View Dependent Claims (42, 43, 44, 45, 46, 47)
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48. An intermodulation compensator comprising:
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a processor to accept an input signal and to compute expected in-band interfering signals based on second order and third order input intercept points (IIP2 and IIP3) for a receiver; a finite impulse response (FIR) filter to pass intermodulation products in a bandwidth of a signal of interest; an adjuster to adjust an intermodulation cancellation signal phase and amplitude; an inverter to invert the intermodulation cancellation signal; and an adder to add the inverted intermodulation cancellation signal to another signal, wherein; the processor is coupled to the FIR filter; the controller is coupled to the FIR filter and to the inverter; and the adder is coupled to the inverter. - View Dependent Claims (49, 50, 51, 52)
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Specification