TRANSMIT SIGNAL CANCELATION APPARATUS AND METHODS
First Claim
1. A radio frequency (RF) receive-band filter in a wireless base station, comprising:
- an observation chain in a receive path to receive a composite RF signal sum including a received signal component r(t), a transmitter leakage signal component l(t) and a subtractive correction signal component c(t) and to amplify and convert the time domain sum of [r(t)+l(t)−
c(t)] to a digital domain data set f(n);
an adaptation chain communicatively coupled to the observation chain to receive a digital baseband data set x(n) from a transmitter generating the transmitter leakage component l(t), to digitally down-convert and filter f(n) to a baseband frequency associated with x(n) to obtain y(n), to generate a set of adaptive cancelation filter coefficients H_C, and to filter x(n) using H_C to obtain a cancelation data set z(n); and
a correction chain communicatively coupled to the adaptation chain to perform digital-to-analog conversion and filtering operations on z(n) to obtain z(t) and to up-convert z(t) to obtain the subtractive correction RF signal component c(t).
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Accused Products
Abstract
Apparatus and methods disclosed herein implement an RF receive-band filter at a receive chain input of a wireless base station with a co-located transmitter and receiver. The RF receive-band filter includes an adaptive filter component to perform filtering operations on samples of a digital baseband or intermediate frequency signal x(n) from a transmit chain associated with the wireless base station. An adaptive filter transfer function is determined in real time such that samples of the baseband transmit signal x(n) are transformed into a cancellation baseband signal z(n). The digital cancelation baseband signal z(n) is then digital-to-analog converted and the resulting analog baseband signal z(t) is up-converted to obtain a subtractive RF cancelation signal c(t). C(t) is summed with a desirable received signal RF component r(t) and an undesirable transmitter leakage RF signal component l(t) appearing at the input to the base station receiver. C(t) cancels l(t), leaving r(t) to be processed by the receiver section of the base station.
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Citations
20 Claims
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1. A radio frequency (RF) receive-band filter in a wireless base station, comprising:
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an observation chain in a receive path to receive a composite RF signal sum including a received signal component r(t), a transmitter leakage signal component l(t) and a subtractive correction signal component c(t) and to amplify and convert the time domain sum of [r(t)+l(t)−
c(t)] to a digital domain data set f(n);an adaptation chain communicatively coupled to the observation chain to receive a digital baseband data set x(n) from a transmitter generating the transmitter leakage component l(t), to digitally down-convert and filter f(n) to a baseband frequency associated with x(n) to obtain y(n), to generate a set of adaptive cancelation filter coefficients H_C, and to filter x(n) using H_C to obtain a cancelation data set z(n); and a correction chain communicatively coupled to the adaptation chain to perform digital-to-analog conversion and filtering operations on z(n) to obtain z(t) and to up-convert z(t) to obtain the subtractive correction RF signal component c(t). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An adaptive filtering apparatus, comprising:
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a down-conversion module to receive a digitized radio frequency (RF) signal f(n) and to down-convert and filter f(n) to produce a baseband received signal y(n), f(n) to include a digitized received signal component r(t), a digitized transmitter leakage signal component l(t), and a subtractive RF correction signal component c(t); a pseudorandom bit sequence (PRBS) module to generate a first PRBS P_A and a second PRBS P_B, P_A to inject into a transmit chain for summing with a digital baseband transmit signal x(n) and P_B to sum with a digital baseband cancelation signal z(n); a correction chain transfer function estimation module H_CORR communicatively coupled to the down-conversion module and to the PRBS module to initiate a P_B operation and to generate a set of estimated correction chain transfer function coefficients H_CORR(k) as 1/N*Σ
[y(n) P_B(n−
k)], H_CORR corresponding to digital-to-analog conversion and up-conversion of z(n) to obtain the RF correction signal component c(t);a cancelation chain transfer function adaptation module H_C communicatively coupled to the down-conversion module to iteratively generate a set of adaptive filter coefficients using an adaptation sequence; and an adaptive filter communicatively coupled to the cancelation chain transfer function adaptation module H_C to load the set of adaptive filter coefficients and to filter x(n) to obtain the digital baseband cancelation signal z(n). - View Dependent Claims (10, 11)
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12. A method of transmitter leakage signal cancelation, comprising:
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receiving a radio frequency (RF) signal sum including a desirable received signal component r(t), a transmitter leakage signal component l(t), and a subtractive correction signal component c(t) at a base station receive chain; amplifying and digitizing the RF signal sum to obtain a digital domain data set f(n); at an adaptation chain, receiving a digital baseband data set x(n) from a transmit chain generating the transmitter leakage component l(t); down-converting and filtering f(n) to a baseband frequency associated with x(n) to obtain y(n); generating a set of adaptive cancellation filter coefficients H_C using an adaptation sequence operating on y(n); filtering x(n) using H_C to obtain a cancellation data set z(n); performing digital-to-analog conversion and filtering operations on z(n) to obtain z(t); and up-converting z(t) to obtain the subtractive correction RF signal component c(t). - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification