Abstract: The representative embodiments discussed in the present disclosure relate to techniques in which the transmission and reception of phase array antennas may be measured to more accurately and more efficiently estimate incidence angles of the associated RF signals. More specifically, in some embodiments, RF signals may be transmitted and received by various subsets of antennas in a pair of phased antenna arrays, and the resulting signals may adaptively filtered and fed back to perform iterations until incidence angles may be accurately determined.

Abstract: Systems and method provided herein relate to reducing distortion of signals introduced by components on a phase path of a radio frequency system polar architecture. To reduce phase path distortion, a pre-distortion is introduced prior to a distortion caused by the components on the phase path. The pre-distortion in conjunction with the component distortion results in a transmission signal that forms its expected shape.

Abstract: The representative embodiments discussed in the present disclosure relate to techniques in which the transmission and reception of phase array antennas may be measured to more accurately and more efficiently estimate incidence angles of the associated RF signals. More specifically, in some embodiments, RF signals may be transmitted and received by various subsets of antennas in a pair of phased antenna arrays, and the resulting signals may adaptively filtered and fed back to perform iterations until incidence angles may be accurately determined.

Abstract: Systems and method provided herein relate to reducing distortion of signals introduced by components on a phase path of a radio frequency system polar architecture. To reduce phase path distortion, a pre-distortion is introduced prior to a distortion caused by the components on the phase path. The pre-distortion in conjunction with the component distortion results in a transmission signal that forms its expected shape.

Abstract: Systems and method for improving operation of a radio frequency system are provided. One embodiment provides a radio frequency system that includes an amplifier device with a first data path and a second data path. Additionally, the radio frequency system includes a controller that instructs the radio frequency system to transmit a calibration signal, which includes a first portion that excites the first data path and a second portion that excites the second data path; determines time skew between the first and second data paths based at least in part on phase shift between a first sample of a feedback signal and the first portion, phase shift between a second sample of the feedback signal and the second portion, or both; and instructs the radio frequency system to adjust delay applied on the first data path, the second data path, or both based at least on the time skew.

Abstract: Communication processing paths include distortions, such as DC offset in the baseband analog path, local oscillator feed-through distortion, and nonlinearity of gm's and power amplifiers which are calibrated for, separately or in combination. The cascaded DC offset and nonlinear distortions are modeled separately or in combination using even-and-odd order polynomials. A loopback path from the output of one or more distortion causing devices passes through a measurement and calculation module. The calculation module calculates predistortion polynomial's coefficients which will be stored in a look-up table to be used by a baseband predistorter to calibrate the path. The look-up table is stored locally or remotely.

Abstract: Communication processing paths include distortions, such as DC offset in the baseband analog path, local oscillator feed-through distortion, and nonlinearity of gm's and power amplifiers which are calibrated for, separately or in combination. The cascaded DC offset and nonlinear distortions are modeled separately or in combination using even-and-odd order polynomials. A loopback path from the output of one or more distortion causing devices passes through a measurement and calculation module. The calculation module calculates predistortion polynomial's coefficients which will be stored in a look-up table to be used by a baseband predistorter to calibrate the path. The look-up table is stored locally or remotely.

Abstract: A class of non data-aided cyclic based robust estimators for frequency offset estimation of multi-carrier systems is disclosed. The use of sufficient statistics provides a minimum variance unbiased (MVU) estimate of the frequency offset under complete knowledge of timing offset error. The Neyman-Fisher factorization theorem and Rao-Blackwell-Lehmann-Scheffe theorem are used to identify the sufficient statistic and appropriate mapping functions. It is shown that there is but one function of the sufficient statistics which results in the minimum variance estimate among the possible class of cyclic-based estimators. Also, a moment estimator of frequency offset is provided to obtain a consistent estimate of carrier offset under uncertain symbol timing error. The moment estimator does not rely on any probabilistic assumptions. Thus, its performance is insensitive to the distribution of the additive noise.

Abstract: A class of non data-aided cyclic based robust estimators for frequency offset estimation of multi-carrier systems is disclosed. The use of sufficient statistics provides a minimum variance unbiased (MVU) estimate of the frequency offset under complete knowledge of timing offset error. The Neyman-Fisher factorization theorem and Rao-Blackwell-Lehmann-Scheffe theorem are used to identify the sufficient statistic and appropriate mapping functions. It is shown that there is but one function of the sufficient statistics which results in the minimum variance estimate among the possible class of cyclic-based estimators. Also, a moment estimator of frequency offset is provided to obtain a consistent estimate of carrier offset under uncertain symbol timing error. The moment estimator does not rely on any probabilistic assumptions. Thus, its performance is insensitive to the distribution of the additive noise.

Abstract: A signal-to-noise estimator is provided for estimating the signal-to-noise ratio in wireless fading channels. The estimator can be applied to likelihood ratio estimation of turbo decoders in third generation wide-band code division multiple access (WCDMA) systems. Time-multiplexed samples of pilot symbols from a wireless receiver are supplied to the estimator to obtain individual estimates of signal power and/or noise power. The estimator uses a de-correlating filter in which the coefficients are known functions (such as eigen-vectors) of the auto-correlation matrix for a wireless channel. The decorrelating filter is used by the estimator to map an observation vector into a set of statistically independent samples. The energy of each vector component is computed individually and combined to produce an aggregate sum for the vector. The aggregate sum can be subtracted from the pilot tone power in order to produce an estimate of noise power.

Abstract: A class of non data-aided cyclic based robust estimators for frequency offset estimation of multi-carrier systems is disclosed. The use of sufficient statistics provides a minimum variance unbiased (MVU) estimate of the frequency offset under complete knowledge of timing offset error. The Neyman-Fisher factorization theorem and Rao-Blackwell-Lehmann-Scheffe theorem are used to identify the sufficient statistic and appropriate mapping functions. It is shown that there is but one function of the sufficient statistics which results in the minimum variance estimate among the possible class of cyclic-based estimators. Also, a moment estimator of frequency offset is provided to obtain a consistent estimate of carrier offset under uncertain symbol timing error. The moment estimator does not rely on any probabilistic assumptions. Thus, its performance is insensitive to the distribution of the additive noise.

Abstract: A method for synchronizing multi-carrier signals in an orthogonal frequency division modulation (OFDM) data transmission system is disclosed which provides maximum likelihood estimation of timing offset and frequency offset. The estimates are able to compensate the estimation error over an entire span of observed data samples. The method requires no training sequence thus enabling blind frequency compensation. The method provides a joint probability density function for the estimates which consists of two terms; one generated from observed data received during a first interval and one generated from observed data received during a second, following, interval. The estimates provided by the method are therefore maximal likelihood over the entire span of observed signals and are a significant improvement over estimates provided by methods based only observations during the first interval. The method is mathematically robust and computationally and statistically efficient.