922 results about "Phase rotation" patented technology

An image display system and associated method for image displaying The system includes an image source configured to generate image light, projection optics configured to project the image light, and a polarizing beam splitter optically coupled to the projection optics and configured to propagate into a first optical path first polarized light having a first polarization and to propagate into a second optical path second polarized light having a second polarization The system includes a quarter wave converter disposed in the first optical path and configured to rotate the first polarization by a quarter phase as the first polarized light first passes through the quarter wave converter, and includes a reflective screen disposed in the first optical path and configured to reflect rotated first polarized light from the quarter wave converter back through the quarter wave converter for further quarter phase rotation.

A modulator (10) and method provides a programmable phase rotation for supporting different modulation formats and different phase rotations. The modulator (10) includes a programmable symbol counter (32) and symbol phase rotation logic (31) operatively responsive to programmable phase rotation size data (36) and programmable counter size data (30). The modulator (10) can be used to communicate with different modulation formats employing different phase rotation conventions as used in different communication systems. The symbol phase rotation logic (31) produces rotated in-phase data (20) and rotated quadrature data (22) in response to receiving at least received symbol data (24), programmable phase rotation size data (36), and symbol count data (32) based on programmable counter size data (30). According to another embodiment, the phase rotations of the modulator (10) may be dynamically selectable such that the phase rotations may be selected to accommodate changes in channel characteristics in real time.

Aspects of a method and system for utilizing Givens rotation to reduce feedback information overhead are presented. Aspects of the system may include a receiver that may enable computation of a beamforming matrix for signals received from a transmitter in a multiple input multiple output (MIMO) communication system. The receiver may enable computation of Givens rotation angles and / or phase rotation angles based on the computed beamforming matrix. The receiver may also enable feedback of information containing the Givens rotation angles and / or phase rotation angles to the transmitter.

A method for automatically detecting a packet mode in a wireless communication system supporting a multiple transmission mode includes: acquiring at least one of data rate information, packet length information and channel bandwidth information from a transmitted frame; and determining the packet mode on the basis of the phase rotation check result of a symbol transmitted after a signal field signal and at least one of the data rate information, the packet length information and the channel bandwidth information acquired from the transmitted frame.

Space-time code, and methods for constructing space-time codes are provided. The space-time coder performs a respective linear transformation on each of P sets of K modulated symbols of a modulated symbol stream to produce P sets of T linearly transformed symbols, applies a respective phase rotation to each set of T linearly transformed symbols to produce a respective set of T phase rotated symbols, and performs a threading operation on the sets of T phase rotated symbols to produce P threaded sequences that define M output sequences; the threading operation being such that each threaded sequence is an allocation of output sequences over time of a respective one of the P sets of T phase rotated symbols in which all of the output sequences are used by each threaded sequence; during each of T symbol periods, a respective one of the P threaded sequences includes a symbol from one of the P sets of phase rotated symbols; and at least one symbol from each set of phase rotated symbols appears in each output sequence; where M>=2, 2<=P<=M, and T>=M and M>=K.

Aspects of a method and system for utilizing Givens rotation expressions for quantization for a general beamforming matrix in feedback information. In one aspect of the invention, feedback information is computed at the receiving MIMO wireless device based on a geometric mean decomposition (GMD) method. The feedback information may include a matrix that describes a wireless medium. The matrix may represent a multiplicative product of at least one rotation matrix and at least one diagonal phase rotation matrix. Each of the rotation matrices may include at least one matrix element whose value is based on Givens rotation angle. The transmitting MIMO wireless device may subsequently transmit a plurality of signals via the wireless medium based on the received matrix information. The signal strength and / or signal to noise ratio (SNR) measurement (as measured in decibels, for example) associated with each of the transmitted plurality of signals may be about equal.

A low overhead long preamble and the corresponding channel estimator for MIMO-OFDM systems that are backward compatible with current 802.11a systems. The preamble has a first training sequence and a second training sequence, wherein the second training sequence is a phase rotation of the first training sequence. The first training sequence comprises a 802.11a training sequence. The preamble can further include multiple training sequences, wherein each training sequence is a different phase rotation of the first training sequence.

An apparatus and method for preventing power imbalance between antennas in a closed-loop MIMO system are provided. In a transmitter in the MIMO system, a first calculator generates a vector by multiplying a transmission vector by a beamforming matrix and a second calculator generates a plurality of antenna signals by multiplying the vector by a predetermined phase rotation matrix.

A low-cost minimal-loss zero-maintenance flywheel battery, to store electric power from a DC power source by conversion to kinetic energy, and regenerate electric power as needed. Its vertical spin-axis rotor assembly is supported axially by repelling annular permanent magnets, and is centered by ceramic ball bearings which have axial preload that prevents vibration and augments axial rotor support. A regenerative multi-pole permanent-magnet motor, controlled by its 2-phase stator current, and connected by power and signal conductors to power interface electronics, is integrated within the flywheel assembly, in a vacuum enclosure supported by a self-leveling structure. Sinusoidal 2-phase stator currents are controlled by high-frequency pulse-width-modulated H-bridge power electronics that draw and regenerate controlled DC current with minimal ripple, responsive to respective 2-phase rotation angle sensors, the DC power voltage, and other settings. The electronics includes logic and over-voltage protection to prevent otherwise possible damaging current and voltage.

Channel estimation values of pilot symbols for channel compensation of data symbols in an OFDM receiver can be used, even in cases where FFT extract position differs for each frame. The OFDM receiver is characterized in having a circuit which calculates the amount of phase rotation that is generated by the difference in timing at which the individual symbols are extract as objects of a fast Fourier transform when the fast Fourier transform processing is performed by a fast Fourier transform circuit, and further a circuit which corrects the amount of phase rotation for the channel estimation value determined by a channel estimating circuit.

A system and method are provided for carrier frequency offset (CFO) and Doppler frequency estimation and correction for Orthogonal Frequency-Division Multiple Access (OFDMA) and Single Carrier-Frequency-Division Multiple Access (SC-FDMA) signals in a wireless communications receiver. The receiver is capable of accepting a plurality of multicarrier signals transmitted simultaneously from a plurality of transmitters, with overlapping carrier frequencies and orthogonal reference signals. For each multicarrier signal, a channel estimate is performed and the channel is equalized. Then, a frequency offset is estimated between the transmit carrier frequency of each multicarrier signal and a receiver local oscillator frequency using either the phase rotation of data constellations as a function of time or the phase rotation of channel estimates as a function of time. The receiver supplies the CFO / Doppler frequency estimates and corrects the equalized symbols prior to demodulation.

A wireless communication device that transmits a wireless signal by carrying out linear precoding processing using a plurality of transmission antennas is provided with: a phase pattern control unit for selecting a phase pattern that reduces peak-to-average power ratio; a phase rotation unit for carrying out phase rotation on a modulation signal using the phase pattern selected in the phase pattern control unit; a control signal generation unit for generating a control signal based on the phase pattern selected in the phase pattern control unit; and a preceding unit for carrying out linear precoding processing on output signals from the phase rotation unit and output signals from the control signal generation unit.

A weight vector computing unit derives amounts of phase rotation for a plurality of multicarrier signals, respectively, and rotates the phase of a weight vector. A combining unit weights respectively a plurality of multicarrier signals with the phase-rotated weight vector, combines weighting results, and determines a combined result. A receiving weight vector computing unit remodulates the determined result and derives a first phase difference between the plurality of multicarrier signals and a result of the remodulation. The receiving weight vector computing unit remodulates the values of pilot signals and derives a second phase difference between the plurality of multicarrier signals and a result of the remodulation. Further, the receiving weight vector derives phase rotation amounts based on the first phase difference and the second phase difference.

Improving the accuracy of estimation of channel responses in receiving signals from a plurality of antennas is disclosed. A transmitting device of a base station includes a preamble A generating unit 010, a preamble B generating unit 011, phase rotating units 012 and 013, multiplexing units 014 and 015, an forward error correction coding unit 016, an S / P converting unit 017, a mapping unit 018, a changeover switch 019, IDFT (or IFFT) units 020 and 026, P / S converting units 021 and 027, GI (Guard Interval) inserting units 022 and 028, D / A converting units 023 and 029, radio transmitting units 024 and 030 and antenna units 025 and 031. In the preamble A generating unit 010 and the preamble B generating unit 011, a preamble A and a preamble B (see the packet format in FIG. 1) are generated, respectively. The preamble A is outputted to the multiplexing units 014 and 015, while the preamble B is outputted to the phase rotating units 012 and 013. The phase rotating units 012 and 013 to which the preamble B has been inputted give continuous phase rotation to subcarriers of the preamble B. In the transmitting device of the base station according to this embodiment, the phase rotating unit 012 does not give phase rotation, but only the phase rotating unit 013 gives phase rotation to the preamble B.

A radar apparatus and method for determining the range to and velocity of at least one object comprising, transmitting a plurality of RF signals, each comprising a particular frequency and being transmitted during a particular unique finite period, the plurality of signals collectively comprising at least one first subset of signals having the same frequency and at least one second subset of signals having different frequencies, receiving the plurality of signals after reflection from an object, determining a phase difference between each of the signals and the corresponding reflected signal, each piece of phase difference information herein termed a sample, organizing the samples in two-dimensions wherein, in a first dimension, all samples have the same frequency and, in a second dimension, all consecutive samples are separated from each other by a fixed time interval; processing the samples in the first dimension to determine a phase rotation frequency corresponding to the samples in the first dimension, the phase rotation frequency comprising a Doppler frequency for the at least one object, processing the samples in the second dimension to determine a second phase rotation frequency corresponding to the samples in the second dimension; the phase rotation frequency comprising Doppler frequency and range frequency for the at least one object; comparing the first phase rotation frequency to the second phase rotation frequency to distinguish range frequency from Doppler frequency of the at least one object; and converting the Doppler frequency to a velocity of the object and converting the range frequency to a range of the object.

The present specification relates to a method for transmitting, by a terminal, a demodulation reference signal (DMRS) in a wireless communication system supporting narrow-band (NB)-Internet of things (IOT), the method comprising: generating, for single tone transmission, a reference signal sequence to be used for demodulation; mapping the reference signal sequence to a plurality of symbols; and transmitting, in the plurality of symbols, the demodulation reference signal to a base station by using a single tone, wherein phase rotation is applied to each of the plurality of symbols.

The present invention provides an apparatus and an associated method for sampling timing compensation, which can estimate sampling frequency offset between the receiver and transmitter of a multi-carrier system according to estimated frequency responses of two consecutive received symbols within each pilot subchannel, and compensate an accumulated sampling timing offset resulted from the sampling frequency offset. When the accumulated timing offset is not large, the apparatus uses a phase rotator to compensate with a corresponding accumulated phase rotation in frequency domain. When the accumulated timing offset is large, the apparatus first compensates with a specific timing offset in time domain, and then uses the phase rotator to compensate with a phase rotation corresponding to the remaining timing offset in frequency domain. A timing controller is used to compensate with the specific timing offset by adjusting a clock generator or a cyclic prefix remover of the receiver.

A system, transmitter, method, and computer program product apply a performance improvement characteristic, such as phase rotation or power allocation, to both a known preamble and a data payload of a transmitted data packet, such that existing multi-carrier receivers are capable of decoding the data payload with the performance improvement characteristic applied. The performance improvement characteristic is applied by vector-matrix multiplication of the preamble and the data payload by the performance improvement characteristic.

In closed-loop transmission diversity, a communication terminal apparatus calculates a phase correcting value for compensating for an effect of phase rotation due to the transmission diversity, using known feedback information, and corrects a received signal on a communication channel based on the phase correcting value, or corrects a channel estimation value based on the phase correcting value.

A timing and frequency offset estimation method for OFDM use an analytic tone in calculating timing offset estimation and a frequency offset estimation. An analytic tone includes a signal that contains only one subcarrier and has characteristics of a uniform magnitude and a uniform phase rotation. The estimation algorithm with an analytic tone is based correlation function. By changing the interval between two samples in correlation, the maximum estimation range for the frequency offset can be extended to ±N / 2 subcarrier spacing, where N is the number of total subcarriers. Thus, the frequency synchronization scheme for OFDM systems has a wider range and a more simple complexity than traditional ones requiring separate fine and coarse synchronization.

An input unit inputs respectively a plurality of partial images corresponding to a user to be authenticated. An extraction unit extracts feature points of a fingerprint respectively from the plurality of partial images inputted. A generation unit synthesizes the feature points extracted respectively from the plurality of partial images and then generates feature point information for authentication. An acquisition unit acquires reference feature point information. A rotation unit performs phase rotation on the generated authentication feature point information so that a directional component, namely, a phase component, contained in the generated authentication feature point information approaches that contained in the acquired reference feature point information. An authentication unit authenticates the authentication feature point information whose phase has been rotated, based on the reference feature point information.

A phase rotation amount estimating unit (210) rotates a channel estimation value of a signal in a common pilot channel (B) through a candidate phase rotation amount θ (θ=0, 180) for synthesizing with a channel estimation value of a signal in a common pilot channel (A). A phase rotation is estimated based on the highest one of orthogonalities between this synthesis result and channel estimation values of signals in individual channels. A channel estimation value synthesis unit (211) synthesizes a value obtained by rotating a channel estimation value of a signal in the common pilot channel (B) through a phase rotation amount θ with a channel estimation value of a signal in the common pilot channel (A), whereby the reliability of a channel estimation value can be enhanced in a transmission diversity-introduced radio communication system.

Provided is a transmitting device which improves a data rate while maintaining channel estimation accuracy, or improves channel estimation accuracy while maintaining a data rate, in a MIMO-OFDM system. In the transmitting device, a transmitting antenna information adding section (104) adds transmitting antenna information to a pilot signal by performing different phase rotation to the separate pilot signal by transmitting antenna by having a common pilot signal as a reference phase. A pilot arranging section (107) is previously provided with, as a conversion table, a corresponding relationship between combination information of the transmitting antenna and a subcarrier to be used for transmission of the pilot signal and control information. The pilot arranging section (107) allocates the pilot signal outputted from the transmitting antenna information adding section (104) to the subcarrier to have the combination information in accordance with the control information.

A radio receiving apparatus and radio receiving method are provided that enable the overall apparatus circuit scale to be reduced, and small apparatus size and low apparatus cost to be achieved, without increasing the processing load, together with a mobile station apparatus and base station apparatus equipped with this radio receiving apparatus. A phase control section (290) holds a phase rotation amount of each subcarrier signal due to the delay in the sampling timing of the second antenna with respect to the first antenna, decided in advance according to the number of antennas of the radio receiving apparatus and the subcarrier frequencies. The phase control section (290) performs phase rotation by the held phase rotation amount of each of N subcarrier signals output from an FFT section (240-2) corresponding to the second antenna.

The invention provides a novel method of transmit beamforming, which allows compact analog implementation of complex digital algorithms without compromising their features. It is aimed to support envelope shaping, apodization, and phase rotation per channel and per firing. Each of three embodiments represents a complete transmit channel driven by pulse-width modulated (PWM) waveforms stored in a conventional sequence memory. PWM signals controls the transmit pulse envelope (shape) by changing the duty cycle of the carrier. Beamformation data are loaded prior to a firing via serial interface. Under the direction of a controller, the circuitry allows high precision (beyond sampling rate) phase rotation of the carrier. It also provides transmit apodization (aperture weighting), which maintains an optimal trade-off among low sidelobe level and widening of the mainlobe. Implementing such an IC, the manufacturing cost of a high-end ultrasound system can be reduced. Equally, the proposed solution makes the benefits of digital transmit beamformers available to midrange and entry-level machines since it merely requires a modified programming of the sequence memory.

A transmitter employing an OFDM system, including a phase rotating portion which gives a same phase rotation amount to each group configured with a plurality of consecutive subcarriers modulated by a data symbol or a known symbol, a rotation amount determining portion which sets a phase rotation for each antenna set or each transmitter, and a scheduling portion which determines an existence of phase rotation.

A synchronization of a pilot assisted channel estimation orthogonal frequency division multiplexing can be achieved by receiving a signal containing pilot symbols, providing an initial time and frequency synchronization to the signal, phase rotating the signal across time, transforming the signal with a fast Fourier transformation, phase rotating the signal across frequency, extracting the pilot symbols and generating a channel estimator. The phase rotating across time and the phase rotating across frequency are controlled by a phase rotation controller in accordance with the channel estimator. The initial time and frequency synchronization synchronizes the signal such that intercarrier interference effects and intersymbol interference effects are negligible. The signal may include plural carrier frequencies each having an arrival timing offset and a frequency offset. The signal may also include delay spread or Doppler spread. The phase rotation controller measures a phase different between the channel estimator at times k and k+Δk, where k is time and Δk is a symbol period and measures a phase difference between the channel estimator at frequencies n and n+Δn, where n is tone frequency and Δn is a frequency spacing between adjacent tones.

A method of generating preamble sequence is disclosed. A channel used by a wireless device may be divided into four sub-channels, and the method includes forming a preamble sequence of a first sub-channel, making three replicas of the preamble sequence of the first sub-channel, each replica with a phase rotation of a first angle, a second angle, and a third angle respectively, for forming each preamble sequence of a second sub-channel, a third sub-channel, and a fourth sub-channel, and arranging the preamble sequences of the first, the second, the third, and the fourth sub-channels to form a preamble sequence of the channel.