Patent application number | Description | Published |
20090196274 | FREQUENCY ERROR ESTIMATION - Aspects relate to frequency estimation and tracking. Frequency information is extracted based on an observation of a single symbol carrying pilot tones, which can be at any bandwidth location. Specifically, the frequency error information is extracted after selecting tones assigned to a specific user. The frequency error can be corrected based on the estimation. Further, the disclosed aspects can be applied to multi-path environments. | 08-06-2009 |
20090296666 | MULTIPLEXING ARRANGEMENTS FOR MULTIPLE RECEIVE ANTENNAS - A method and apparatus processes a plurality of analog signals in a transceiver with multiple receive (Rx) antennas in a wireless communication system. By appropriate combining of the analog signals of each Rx antenna, this scheme allows a reduction in the number of the front end components, for example, filters, mixers and Analog to Digital Converter (ADC) devices. Subsequently, the signals are separated digitally by virtue of their unique code. The benefits associated with this scheme are at least threefold: reduced cost, area, and power consumption of a multiple antenna terminal. Additionally, proper parameter settings increase signal to Quantization Noise Ratio (SQNR) at the ADC output. | 12-03-2009 |
20100034327 | JOINT TIME-FREQUENCY AUTOMATIC GAIN CONTROL FOR WIRELESS COMMUNICATION - Techniques for performing joint time-frequency automatic gain control (AGC) by a receiver are described. In an aspect, the receiver may transform time-domain samples with a fast Fourier transform (FFT) to obtain frequency-domain symbols and may detect for saturation of the frequency-domain symbols. The receiver may adjust a gain based on whether saturation is detected and may apply the gain prior to the FFT. In one design, the receiver may use a nominal value for a setpoint if saturation is not detected and may reduce the setpoint if saturation is detected. The receiver may adjust the gain based on the setpoint, which may determine the average power of the time-domain samples. In another design, the receiver may determine the gain based on a gain offset and may vary the gain offset based on whether saturation is detected. For both designs, the receiver may apply the gain on digital samples and/or an analog signal prior to the FFT. | 02-11-2010 |
20100217553 | IMPEDANCE CHANGE DETECTION IN WIRELESS POWER TRANSMISSION - Exemplary embodiments are directed to wireless power transfer. Energy from a transmit antenna is coupled to internal signals on a transmitter. An impedance measurement circuit generates an impedance indication signal for indicating an impedance difference between the coupled internal signals by comparing them. A controller samples the impedance indication signal and determines digital signaling values responsive to changes in the impedance indication signal. The impedance measurement circuit measures one or more of magnitude difference of the internal signals, phase difference of the internal signals, and changes in power consumed by an amplifier coupled between the RF signal and the transmit antenna. A transmitter generates the electromagnetic field with a transmit antenna responsive to a Radio Frequency (RF) signal to create a coupling-mode region within a near field of the transmit antenna. | 08-26-2010 |
20110069749 | NONLINEAR EQUALIZER TO CORRECT FOR MEMORY EFFECTS OF A TRANSMITTER - Techniques for correcting for memory effects of a transmitter are described. In an exemplary design, a receiver obtains input samples including a desired signal transmitted by a transmitter having memory effects. The receiver performs nonlinear equalization on the input samples to obtain first equalized samples, performs linear equalization on the input samples to obtain second equalized samples, and determines output samples based on the first and second equalized samples. The nonlinear equalization corrects for the memory effects and nonlinearities of the transmitter and possibly nonlinearities and memory effects of the receiver. The receiver may jointly determine coefficients for both linear and nonlinear equalization based on an adaptive algorithm. The receiver processes (e.g., demodulates and decodes) the output samples to recover data sent in the desired signal by the transmitter. | 03-24-2011 |
20110103455 | ADAPTIVE DIGITAL POST DISTORTION REDUCTION - A method for adaptive digital post distortion reduction is described. An analog radio frequency (RF) signal is received. The frequency of the analog RF signal is downconverted using analog circuitry. The analog RF signal is converted to a digital signal using an analog to digital converter (ADC). Digital post distortion reduction is applied to the digital signal to reduce nonlinearities in the digital signal. | 05-05-2011 |
20110149714 | METHOD AND APPARATUS FOR ADAPTIVE NON-LINEAR SELF-JAMMING INTERFERENCE CANCELLATION - Certain embodiments of the disclosure propose a method for cancelling co-channel interference (self-jamming) generated by nonlinearities in the radio-frequency (RF) front-end devices. The proposed method utilizes an adaptive non-linear filter to generate a distorted version of the transmitted signal. The self-jamming interference may be mitigated utilizing the distorted signal through adaptive cancellation. | 06-23-2011 |
20120140860 | NON-LINEAR ADAPTIVE SCHEME FOR CANCELLATION OF TRANSMIT OUT OF BAND EMISSIONS - A method and apparatus for a non-linear adaptive scheme for transmit out of band emission cancellation is provided. Embodiments disclosed herein provide a method for removing unwanted transmitter emissions from a composite received signal. The method performs the steps of: extracting the I and Q samples from a modulator output; inputting the I and Q samples to a non-linear filter; applying weights to the non-linear filter outputs, combining the non-linear filter outputs to generate a broadband emission estimate; selecting a portion of a transmit emission in a desired portion of a receive band; subtracting an output of the non-linear filter from a composite signal; and feeding back a residual error to the non-linear filter; adapting the non-linear filter iteratively. | 06-07-2012 |
20130040555 | ROBUST SPUR INDUCED TRANSMIT ECHO CANCELLATION FOR MULTI-CARRIER SYSTEMS SUPPORT IN AN RF INTEGRATED TRANSCEIVER - A method and apparatus for eliminating transmit echo spurs is provided. The method includes the steps of: estimating a distortion effect applied to a transmit signal by a duplexer stop band. Next, the contribution of a primary component of the spur is estimated. An image component of the spur is estimated after the primary contribution has been estimated. The transmit echo is then subtracted from the composite desired signal by digitally subtracting the distortion effect, the primary component of the spur, and the image component of the spur, producing the desired composite transmit signal without the transmit echo. | 02-14-2013 |
20130044791 | JOINT LINEAR AND NON-LINEAR CANCELLATION OF TRANSMIT SELF-JAMMING INTERFERENCE - Certain aspects of the present disclosure propose an adaptive joint linear and non-linear digital filter that can adaptively estimate and reconstruct cascaded effects of linear and non-linear self-jamming distortions introduced by non-linearities in the transmit and/or receive chains. The proposed digital filter may be used to cancel second-order inter-modulation distortion (IM2) generated in the receive chain and/or harmonic distortion generated in the transmit chain, as well as other distortions introduced by the transmit/and or receive chains. | 02-21-2013 |
20130094550 | SHARED FEEDBACK FOR ADAPTIVE TRANSMITTER PRE-DISTORTION - A modem is described. The modem includes a transmitter. The transmitter includes a digital pre-distortion module and a power amplifier. The modem also includes one or more selected shared receivers. The one or more selected shared receivers generate a feedback signal for the digital pre-distortion module. The modem further includes a feedback switch. The feedback switch selectively couples the one or more selected shared receivers to an output of the transmitter. | 04-18-2013 |
20140086162 | ADAPTIVE NON-LINEAR INTERFERENCE CANCELLATION USING SIDE-BAND INFORMATION - A user equipment (UE) may reduce non-linear interference on a signal received at a receiving RAT by using a determined operating parameter of a transmitting radio access technology (RAT) of the user equipment (UE), which transmits a signal according to the operating parameter. The UE may estimate the non-linear interference in digital baseband to a receiving RAT of the UE from a digital baseband portion of the transmitted signal of the transmitting RAT by applying non-linear transformation based on the determined operating parameter of the transmitting RAT and cancel the estimated non-linear interference in baseband from a signal received by the receiving RAT. | 03-27-2014 |
20140247757 | MULTI-TAP ADAPTIVE FILTER FOR TRANSMIT SIGNAL LEAKAGE CANCELLATION - Exemplary embodiments are directed to systems, devices, and methods for mitigating effects of transmit signal leakage. A transceiver may include a transmitter and a receiver. The transceiver may further include a multi-tap analog adaptive filter coupled to each of the transmitter and the receiver and configured to generate an estimated transmit leakage signal based on at least a portion of a transmit signal from the transmitter and an error signal from the receiver. | 09-04-2014 |
20140269857 | Adaptive Non-Linear Interference Cancellation For Intermodulation Distortion - A wireless communication device including two or more aggressor transmitters and a victim receiver that is adversely affected by intermodulation distortion (IMD) components associated with the signals transmitted by the two or more aggressor transmitters. Because the aggressor transmitters and the victim receiver are located on the same device, the transmit waveforms that contribute to the IMD components are known and available. More specifically, digital baseband samples used by the aggressor transmitters to generate the transmit waveforms are available. These digital baseband samples are used to reconstruct the IMD component on the wireless device. This reconstructed (estimated) IMD component is provided to the victim receiver, and is subtracted from a signal received by the victim receiver, thereby effectively removing the IMD component present in this received signal. An adaptive filter using a Volterra series can be used to estimate the IMD component in response to the transmitter digital baseband samples. | 09-18-2014 |
20140301498 | Non-linear Interference Cancellation Across Aggressor Transmitters and Victim Receivers - Systems and methods are disclosed to implement non-linear interference cancellation (NLIC) across chips or dies in communication systems to cancel or mitigate self-jamming interference. A victim transceiver may receive an analog baseband transmit (Tx) signal from an aggressor transceiver. The analog baseband Tx signal may be tapped from a digital analog converter (DAC) of the aggressor transceiver. Alternatively, the analog baseband Tx signal may be generated by the aggressor transceiver using an auxiliary down-conversion and filtering stage. The victim transceiver may receive a composite baseband Rx signal from the victim transceiver front-end. The composite baseband Rx signal includes the desired Rx signal and an interference signal. The victim transceiver may sample the analog baseband Tx signal to generate a digital signal replica of the analog baseband Tx signal for the NLIC operation to cancel or mitigate the interference signal present in the composite baseband Rx signal. | 10-09-2014 |
20150065058 | NON-LINEAR INTERFERENCE CANCELLATION WITH MULTIPLE AGGRESSORS - Disclosed is non-linear interference cancellation (NLIC) on a victim receiver in a communication system in which there is self-jamming interference from multiple aggressor transmitters. The victim receiver may implement cascaded NLIC operations using multiple interference signals in succession to remove the multiple interference signals from the Rx signal and to cancel or mitigate the self-jamming interference. The reconstruction and removal of the interference signals may be ordered based on the expected level of interference from the interference signals on the desired Rx signal. The victim receiver may first perform NLIC operation using the Tx signal from the transmitter aggressor estimated to generate the strongest interference signal to remove the strongest interference signal from the Rx signal first. The victim receiver may perform NLIC operation on the TX signal from the next strongest transmitter aggressor, and so on, to remove interference signals of multiple aggressor transmitters from the Rx signal. | 03-05-2015 |