Method and apparatus to reduce interference in a communication device
First Claim
1. In a communication device having a co-located transmitter and receiver, a method for reducing interference from the transmitter in a received signal, the method comprising the steps of:
- characterizing a transfer function of a transmission path from the transmitter to the receiver;
inputting a transmit baseband signal from the transmitter;
applying the transfer function to the input transmit baseband signal to provide an estimated interference signal;
adaptive filtering the estimated interference signal using feedback control from the receiver signal to dynamically minimize the interference; and
subtracting the estimated interference signal from the received signal to reduce the interference.
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Accused Products
Abstract
An apparatus and method to reduce interference in a communication device particularly effective for second-order interference in direct conversion receiver from a co-located transmitter. This is accomplished by characterizing a transfer function of a transmission path from the transmitter to the receiver and applying this transfer function to the baseband signal from the transmitter to provide an estimation of interference to be expected in the received signal. The estimated interference is subtracted from the receiver baseband signal to reduce interference. Adaptive filtering can also be applied to further minimize interference dynamically.
101 Citations
18 Claims
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1. In a communication device having a co-located transmitter and receiver, a method for reducing interference from the transmitter in a received signal, the method comprising the steps of:
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characterizing a transfer function of a transmission path from the transmitter to the receiver; inputting a transmit baseband signal from the transmitter; applying the transfer function to the input transmit baseband signal to provide an estimated interference signal; adaptive filtering the estimated interference signal using feedback control from the receiver signal to dynamically minimize the interference; and subtracting the estimated interference signal from the received signal to reduce the interference. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. In a communication device having a co-located transmitter and receiver, a method for reducing interference from the transmitter in a received signal, the method comprising the steps of:
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characterizing a transfer function of a transmission path from the transmitter to the receiver including the receiver front end transfer function and a non-linear operation of the receiver mixer; inputting a transmit baseband signal from die transmitter; applying the transfer function to the input transmit baseband signal to provide an estimated interference signal; adaptive filtering the estimated interference signal using feedback control from the receiver baseband signal to dynamically minimize the interference; and subtracting the estimated interference signal from the receiver baseband signal to reduce the interference. - View Dependent Claims (11, 12, 13, 14)
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15. In a communication device having a co-located transmitter and receiver, an apparatus for reducing interference from the transmitter in a received signal, the apparatus comprising:
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an interference estimator that incorporates a transfer function of a transmission path from the transmitter to the receiver; a transmit baseband signal coupled from the transmitter to the interference estimator; an estimated interference signal provided by the interference estimator, the estimated interference signal derived from the application of the transfer function to the transmit baseband signal; a subtractor coupled to the interference estimator and the receiver, the subtracter being operable to apply the estimated interference signal to the receiver to reduce interference in the receiver signal; further comprising a receiver baseband processor that filters and applies gain to the receiver signal, and wherein the transfer function includes a receiver transfer function that characterizes the receiver baseband processor.
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16. In a communication device having a co-located transmitter and receiver, an apparatus for reducing interference from the transmitter in a received signal, the apparatus comprising:
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an interference estimator that incorporates a transfer function of a transmission path from the transmitter to the receiver; a transmit baseband signal coupled from the transmitter to the interference estimator; an estimated interference signal provided by the interference estimator, the estimated interference signal derived from the application of the transfer function to the transmit baseband signal; a subtracter coupled to the interference estimator and the receiver, the subtracter being operable to apply the estimated interference signal to the receiver to reduce interference in the receiver signal, wherein the subtracter is coupled after a receiver baseband processor, and further comprising a feedback control signal coupled to the adaptive filter from the receiver signal after the receiver baseband processor.
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17. In a communication device having a co-located transmitter and receiver, an apparatus for reducing interference from the transmitter in a received signal, the apparatus comprising:
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an interference estimator that incorporates a transfer function of a transmission path from the transmitter to the receiver; a transmit baseband signal coupled from the transmitter to the interference estimator; an estimated interference signal provided by the interference estimator, the estimated interference signal derived from the application of the transfer function to the transmit baseband signal; a subtracter coupled to the interference estimator and the receiver, the subtractor being operable to apply the estimated interference signal to the receiver to reduce interference in the receiver signal, wherein the interference estimator includes an adaptive filter of the real type that operates on a sum of complex channel error signals.
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18. In a communication device having a co-located transmitter and receiver, an apparatus for reducing interference from the transmitter in a received signal, the apparatus comprising:
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an interference estimator that incorporates a transfer function of a transmission path from the transmitter to the receiver; a transmit baseband signal coupled from the transmitter to the interference estimator; an estimated interference signal provided by the interference estimator, the estimated interference signal derived from the application of the transfer function to the transmit baseband signal, wherein the interference estimator includes two real-type adaptive filters operating on each respective complex component of the receiver signal; a subtractor coupled to the interference estimator and the receiver, the subtractor being operable to apply the estimated interference signal to the receiver to reduce interference in the receiver signal.
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Specification