44 results about "Adaptive quadrature" patented technology

An adaptable orthogonal frequency-division multiplexing system (OFDM) that uses a multiple input multiple output (MIMO) to having OFDM signals transmitted either in accordance with time diversity to reducing signal fading or in accordance with spatial diversity to increase the data rate. Sub-carriers are classified for spatial diversity transmission or for time diversity transmission based on the result of a comparison between threshold values and at least one of three criteria. The criteria includes a calculation of a smallest eigen value of a frequency channel response matrix and a smallest element of a diagonal of the matrix and a ratio of the largest and smallest eigen values of the matrix.

A method of reducing channel state information fed back in an adaptive orthogonal frequency division multiple access system when transmitting and receiving data packets between a base station and a mobile station using an orthogonal frequency division multiplexing method comprising adaptive modulation and coding. The method includes: transmitting a data packet comprising information as to whether adaptive modulation and coding is on or off from the base station to the mobile station via a downlink; and tracking a modulation and coding scheme level only when it is determined that adaptive modulation and coding is performed based on the information as to whether adaptive modulation and coding is on or off and feeding back the channel state information obtained from the tracking result from the mobile station to the base station via an uplink.

The invention provides a feedback information transmitting method in self-adapting orthogonal frequency division multiplex (OFDM system, combining self-adapting modulating and coding (MAC) technique with hybrid auto-retransfer request (HARQ) technique and including the following steps: a. a mobile terminal receives data transmitted by access point, then transmits a confirm / nonconfirm (ACK / NACK) information to the access point and simultaneously measures channel quality and obtains channel quality indication (CQI); b. the mobile terminal judges if the measured CQI in a period of time is good a CQI: if it is, transmit the CQI to the access point and otherwise do not transmit the CQI. It can reduce the overhead of feedback signalling, thus reducing the ascending link interference in the self-adapting OFDM system and increasing the system efficiency.

An adaptable orthogonal frequency-division multiplexing system (OFDM) that uses a multiple input multiple output (MIMO) to having OFDM signals transmitted either in accordance with time diversity to reducing signal fading or in accordance with spatial diversity to increase the data rate. Sub-carriers are classified for spatial diversity transmission or for time diversity transmission based on the result of a comparison between threshold values and at least one of three criteria. The criteria includes a calculation of a smallest eigen value of a frequency channel response matrix and a smallest element of a diagonal of the matrix and a ratio of the largest and smallest eigen values of the matrix.

The invention discloses a method and a device for detecting cloth flaws based on adaptive orthogonal wavelet transform. Manual eye detection and an original automatic flaw detecting method in which wavelet transform is carried out after a wavelet basis is manually selected are replaced. The defects of traditional manual eye detection, such as low detection speed, low efficiency, false detection and high detection leaking rate are overcome. The problem of the original flaw detecting method based on wavelet transform that the detection precision is low as the wavelet basis is not optimized is solved. The optimal wavelet basis matched with a cloth texture is selected by an improved quantum rotating gate quantum genetic algorithm, the quantum rotating angle is regulated by a dynamic strategy, fine adaptive search is realized, the variety is enriched through introducing mutation operation, and the optimization capability of the algorithnm is improved through combining chaotic search. The flaw detecting method has the advantages of high speed, high accuracy, simplicity in operation and high efficiency and has great application prospects.

A phase-locked loop and method for estimating a phase angle of a three-phase reference signal is disclosed, which includes an adaptive quadrature signal generator configured to calculate an estimated first state and an estimated second state of a model of an unbalanced three-phase system at a fundamental frequency of the reference signal on a basis of the reference signal and an estimated fundamental frequency; a reference frame transformation block configured to calculate a direct component and a quadrature component in a rotating reference frame synchronous with an estimated phase angle on a basis of the fundamental positive sequence component and the estimated phase angle, and configured to determine an estimate of an amplitude of the fundamental positive sequence component on the basis of the direct component; and an estimator configured to determine estimates of the estimated fundamental frequency and the estimated phase angle on the basis of the quadrature component.

The invention discloses a magnetic resonance image reconstruction method based on an adaptive orthogonal basis, and the method comprises the following steps: (1) obtaining original k-space data, carrying out the Fourier inversion of the sampled k-space data, and obtaining an original reconstruction image; (2) building a reconstruction model based on compression sensing under the constraint of the orthogonal basis; (3) partitioning the original reconstruction image, randomly extracting some image blocks for the learning of the orthogonal basis, and obtaining a group of adaptive orthogonal basis; (4) employing a hard threshold method to achieve the sparse representation of all image blocks based on the adaptive orthogonal basis; (5) employing a least square method to updating the reconstruction image, and obtaining a current reconstruction image; (6) judging whether the current reconstruction image meets the condition of convergence or not: if the current reconstruction image meets the condition of convergence, the current reconstruction image serves as a final reconstruction image; or else, going to step (7); (7) reducing the value of a regularization parameter, the current reconstruction image serves as the original reconstruction image, and returning to step (3). The method is high in reconstruction speed, and is good in image quality.

The invention discloses a non-linear amplitude phase detection method suitable for a single-phase distortion power grid, and the method comprises the steps: extracting a fundamental wave signal of a single-phase signal through employing a stationary coordinate system phase locking ring method according to a mode of the single-phase distortion power grid, and building an orthogonal signal; building a liapunov function according to the fundamental wave signal of the single-phase signal and the orthogonal signal, and obtaining an adaptive orthogonal generator and a frequency locking ring because the differential coefficient of the liapunov function is less than zero, i.e., system global stability and convergence; and the fundamental wave amplitude and phase of the single-phase signal are obtained according to the adaptive orthogonal generator and the frequency locking ring. The method is designed according to the mode of the single-phase distortion power grid, achieves the estimation of a diagonal frequency signal through employing a liapunov method, does not depend on a conventional linearization method, and guarantees the signal integrity through employing a non-linear method.

An adaptable orthogonal frequency-division multiplexing system (OFDM) that uses a multiple input multiple output (MIMO) to having OFDM signals transmitted either in accordance with time diversity to reducing signal fading or in accordance with spatial diversity to increase the data rate. Sub-carriers are classified for spatial diversity transmission or for time diversity transmission based on the result of a comparison between threshold values and at least one of three criteria. The criteria includes a calculation of a smallest eigen value of a frequency channel response matrix and a smallest element of a diagonal of the matrix and a ratio of the largest and smallest eigen values of the matrix.

The embodiment of the invention provides terminal frequency deviation detection method, device and system. The method comprises the following steps of: scrambling a downlink signal of a to-be-detected voice business channel corresponding to a to-be-detected terminal through a self-adapting quadrature phase shift keying modulation technique; carrying out frequency deviation detection on a scrambled uplink signal on the to-be-detected voice business channel to obtain the frequency deviation detection result of the uplink signal on the to-be-detected voice business channel; and sending the frequency deviation detection result to a base station controller. In the embodiment of the invention, a base station transceiver scrambles the downlink signal of the to-be-detected voice business channel and then carries out the frequency deviation detection on the scrambled uplink signal on the to-be-detected voice business channel, and therefore, the frequency deviation detection result of the uplink signal of the to-be-detected voice business channel can be obtained when the downlink signal of the to-be-detected voice business channel is multiplexed.

A system and method for scheduling cooperative uplink transmissions in a virtual multiple input multiple output (MIMO) wireless communication environment are provided. More specifically, the present invention provides both random and channel aware orthogonal scheduling techniques for identifying a sub-set of N mobile terminals to provide cooperative uplink transmissions for each transmit time interval.

The invention discloses a visible light OFDM system self-adaptive low peak ratio method based on subcarrier reservation. The method comprises the following steps: (1) at a transmitting end, allowing binary bit information flow generated by an information source to be subjected to adaptive orthogonal amplitude modulation to form a frequency domain data signal of the transmitting end; (2) determining the number of reserved subcarriers and corresponding positions in the visible light communication system; (3) performing conjugate symmetry processing on the frequency domain data signal on the OFDMsubcarrier; (4) calculating a reserved subcarrier frequency domain value; (5) performing IFFT operation on the OFDM frequency domain signal, and adding a cyclic prefix to obtain a time domain electric signal for driving the LED; (6) carrying out direct current bias or clipping on the electric signal, and then an LED is driven to emit an optical signal; (7) at a receiving end, converting the optical signal into an electric signal through a photodiode; (8) converting the obtained electric signal into a frequency domain signal; And (9) demodulating to obtain binary information flow. According to the invention, the requirement of the system on the linearity of the power amplifier and the LED lamp is reduced, and the nonlinear distortion is reduced.

The invention discloses a grid-connected synchronous phase-lock method based on an improved series signal delay cancellation algorithm. According to a mathematic model of a single-phase distorted grid voltage, a fundamental component signal of one-phase of voltage is extracted and an orthogonal signal is constructed by using a static coordinate frame phase-locked loop method; a liapunov function is constructed based on the fundamental component signal of one-phase of voltage and the orthogonal signal, and an adaptive orthogonal generator and a frequency-locked loop are obtained because the derivative of the liapunov function is less than zero, which means the global system is in a stable and convergent state; and on the basis of the frequency output quantities of the adaptive orthogonal generator and the frequency-locked loop, feedback to a delay cancellation operator is carried out and thus the grid fundamental period T participates in real-time calculation of a delay operator valpha beta (t-T / n), so that tracking and extraction of the grid fundamental positive-sequence component is still carried out by a cascade stage delay cancellation method in a frequency fluctuation state and thus accurate phase locking of the grid fundamental positive-sequence signal is realized.

In accordance with the present invention, a method and apparatus for estimating the noise and interference over the transmission band for OFDM systems are provided. Noise variance and signal-to-noise ratio (SNR) are important parameters for adaptive orthogonal frequency division multiplexing (OFDM) systems since they serve as a standard measure of signal quality. Conventional algorithms assume that the noise statistics remain constant over the OFDM frequency band, and thereby average the instantaneous noise samples to get a single estimate. In reality, noise is often made up of white Gaussian noise along with correlated colored noise that affects the OFDM spectrum unevenly. Provided is an adaptive windowing technique to estimate the noise power that takes into account the variation of the noise statistics across the OFDM sub-carrier index as well as across OFDM symbols. The proposed method provides many local estimates, allowing tracking of the variation of the noise statistics in frequency and time. A mean-squared-error (MSE) expression in order to choose the optimal window dimensions for averaging in time and frequency is derived.

The invention discloses a millimeter wave channel estimation method based on adaptive compressed sensing. The method comprises the following steps: constructing an optimization problem model of millimeter wave channel estimation; solving an optimal solution of the optimization problem model by adopting an adaptive orthogonal matching pursuit algorithm based on block sparsity; and calculating to obtain a millimeter wave channel estimation result based on the optimal solution of the optimization problem model. According to the scheme, the millimeter wave channel can be estimated under the condition that the number of effective paths in the channel is unknown.

The invention relates to a personalized movie recommendation method based on a self-adaptation orthogonal crossover multi-target optimization algorithm. The personalized movie recommendation method has the advantages that aiming at the optimization insufficiency of a traditional recommendation algorithm to accuracy and non-accuracy which are two opposite indexes, the multi-target optimization algorithm is used to optimize the two targets, and accordingly diversity is increased under the premise that the accuracy is kept; aiming at the defects of the NSGA-II multi-target optimization algorithm,the improved algorithm SMOCDE is provided, the algorithm designs a self-adaptation multi-target orthogonal crossover operator SMOC, and the operator is used to initialize population so as to avoid population distribution unevenness; the operator is used for perform crossover operation, and the convergence performance and distribution performance of population are kept; when the algorithm is applied to the actual problem of personalized movie recommendation, the universality and effectiveness of the algorithm are verified by testing and comparing the algorithm with an existing recommendation algorithm, and the accuracy and diversity of recommendation results are increased.

The present invention relates to a simplified QAM signal constellation symbol-wise remapping scheme for data packet retransmissions to improve performance at a high coding rate. The simplified QAM signal constellation symbol-wise remapping scheme takes advantage of the separate I and Q labeling bits in a QAM signal to reduce the complexity of a receiving node. The present invention also relates to a method for adaptive switching between bit-wise and symbol-wise constellation remapping for data packet transmissions according to channel coding rate to achieve optimum performance across the range of channel coding rates.

The invention provides an adaptive orthogonal wavelet image denoising method based on accurate local variance priori modeling. The method is characterized by carrying out accurate modeling on orthogonal wavelet transform detail coefficient local variance prior distribution through maximum likelihood estimation, thereby realizing a better denoising performance, improving peak signal-to-noise ratio of a de-noised image, and improving visual effect of the de-noised image. The beneficial effects are that the method overcomes the defect that an existing method is not high in local variance estimation, can better express statistical property of the image orthogonal wavelet decomposition detail coefficient, can give a denoising result adaptively, can remove additive white Gaussian noise in a natural image more effectively, and meanwhile, can better protect regions having rich edge and texture detail information and the like in an original image, and improves visual effect and peak signal-to-noise ratio of the de-noised image. The method is low in computation complexity, and is suitable for immense image denoising application in the age of big data.

A link adaptive orthogonal frequency-division multiplexed (OFDM) ultrasonic physical layer is provided that is capable of high data rate communication through metallic structures. The use of an adaptive OFDM subcarrier-based modulation technique mitigates the effects of severe frequency selective fading of the through-metal communication link and improves spectral efficiency by exploiting the slow-varying nature of the channel. To address the potential ill effects of peak-to-average power ratio (PAPR) and to make more efficient use of the power amplifiers in the system, the invention modifies and implements a symbol rotation and inversion-based PAPR reduction algorithm in the adaptive OFDM framework. This joint adaptive physical layer is capable of increasing data rates by roughly 220% in comparison to conventional narrowband techniques at average transmit powers of roughly 7 mW while constrained to a desired BER.

The invention discloses a self-adaptive orthogonal recovery spatial frequency encoding method. The method comprises the following steps: pre-estimating arrival time difference of signals sent by different antennas according to vehicle driving speed and driving direction and like factors, and constructing a delay estimation ring by taking the estimation delay as a center point; performing phase rotation with different degrees on elements in a pre-encoding matrix by using a delay factor so as to compensate the channel non-orthogonality caused by delay; pre-encoding a pilot frequency signal according to two delays obtained by the delay estimation ring on different sub-carriers of the same OFDM code elements at one time slot; performing channel estimation by using the signal decoded by a receiving end, and decoding the received signal by using the conjugate of the channel pulse response; judging the accuracy of the estimation delay by using a delay estimation judgment ring through the receiving end; and modifying the TDOA according to a feedback value through a sending end. Through the method disclosed by the invention, the system signal-to-noise ratio, the bit error rate and the diversity gain and like performances are greatly improved.

The invention discloses a self-adaptive orthogonal recovery coding method based on signal-to-noise ratio estimation. The method comprises the following steps that 1, a base station end performs initial TDOA value estimation by using a pilot frequency sequence sent by a mobile station; 2, the base station performs phase rotation on elements in the precoding matrix by using the estimated TDOA initial value (shown in the specification), performs phase rotation on the elements in the precoding matrix by using the estimated TDOA initial value; and compensates for channel non-orthogonality caused bythe time delay; 3, the channel estimation and symbol decoding is carried out by a signal decoded by a receiving end; 4, a mobile station estimates the signal-to-noise ratio of the decoded symbol andreports the signal-to-noise ratio to a sending end; 5, the sending end tracks and corrects the TDOA estimation value according to a back-off algorithm to obtain a corrected TDOA delay factor (shown inthe specification); 6, the sending end carries out phase rotation on elements in the precoding matrix according to the TDOA delay factor (shown in the specification) obtained by feedback, and encodesa sent signal. The orthogonal recovery coding of the TDOA estimation value can be adaptively tracked and corrected according to the received signal, and the system performance is improved on the premise of not increasing the system overhead.

This invention provides an orthogonal FDMT method adaptively regulating sub-carrier number according to the variance of channel properties and the system characterizing that the receiver utilizes the mutual relation number of the circulation segment prfix of adjacent orthogonal FDM symbols in leading sequence to measure the channel time coherence and utilizes the mutual relation number of the adjacent sub-carrier channel gains of the symbols to measure the frequency coherence. The sender evaluates the optimum value of the sub-carrier number of the next sent data frame according to the time and frequence coherences and takes it as the transmission parameter of data domain orthogonal FDM symbol in the next sent data frame for the adaptive orthogonal FDMT.

The invention discloses a dynamic magnetic resonance parallel reconstruction method based on adaptive orthogonal dictionary learning. A relatively slow dictionary learning algorithm which originally runs in an offline mode is applied to the online mode. A first frame of high-precision sampling serves as a reference, real-time online reconstruction of any n adjacent frames of MR images is achieved,a three-dimensional image small block serves as a reconstruction object, and an orthogonal dictionary serves as a sparse constraint condition and a singular value decomposition algorithm to improve the reconstruction speed and precision.

The invention discloses a sparse adaptive DOA estimation method and system based on a pseudo-inverse perception dictionary, and the method comprises the steps: receiving K narrow-band signal sources through an M-element uniform linear array, and obtaining an observation vector of a noise-free field; taking the observation vector as an initial residual error, adopting a sparsity adaptive orthogonalmatching pursuit method based on a pseudo-inverse perception dictionary, obtaining a residual error value corresponding to the current stage by continuously iterating the step length, obtaining a minimum residual error value according to the convergence comparison of the residual error values of different stages, and obtaining a corresponding sparse coefficient; and obtaining the directions of the non-zero elements in the K narrowband signal sources. According to the method, the convergence value of each step iteration is compared, the step corresponding to the minimum convergence value is used as the sparsity, the threshold error is effectively eliminated, and the application range is expanded; the advantages of the perception dictionary are combined, and a new design criterion of the pseudo-inverse perception dictionary is provided, so the error influence caused by atom strong correlation under the condition of high resolution is overcome, and the direction of the incoming wave is positioned more accurately.

A method and system for increasing the throughput of a wireless channel that sends different data on different multi-path components. The channel can be pre-mapped or dynamically mapped, and the different transmissions can be modulated by different complexity signals such as adaptive quadrature amplitude modulation (AQAM). Each multipath component is coded with a signature that will allow it to be separated at a receiver that has an omni-directional antenna. Common signature techniques can be offset PN codes, orthogonal spreading vectors, orthogonal alphabets and other signature techniques. The received channels can be combined for an overall increase in data-rate or used separate as multiplexed data.

The invention proposes an adaptive orthogonal frequency division multiplexing multi-carrier modulation system. The system is based on a traditional orthogonal frequency division multiplexing (OFDM) multi-carrier modulation system and obtained by introducing adaptive signal processing. Different from the OFDM system, the number of subcarriers in each signal frame in the AD-OFDM system varies with signal characteristics, the number of subcarriers at a transmitting end varies according to the peak-to-average power ratio (PAPR) value of the processed signal per frame, and the PAPR value is calculated to determine the number of subcarriers in the system, so that the PAPR value and power consumption of the system can be effectively reduced. Compared with other methods for reducing the PAPR valuein the OFDM system, the AD-OFDM system can not only maintain the superiority of the OFDM system, but can also reduce the PAPR value more efficiently. The transmitting end of the AD-OFDM system needsto send the number of subcarriers per frame as sideband information to a receiving end.