1189 results about "Channel gain" patented technology

Techniques for adjusting transmit power to mitigate both intra-sector interference to a serving base station and inter-sector interference to neighbor base stations are described. The amount of inter-sector interference that a terminal may cause may be roughly estimated based on the total interference observed by each neighbor base station, channel gains for the serving and neighbor base stations, and the current transmit power level. The transmit power may be decreased if high interference is observed by a neighbor base station and increased otherwise. The transmit power may be adjusted by a larger amount and / or more frequently if the terminal is located closer to the neighbor base station observing high interference and / or if the current transmit power level is higher, and vice versa. The intra-sector interference is maintained within an acceptable level by limiting a received SNR for the terminal to be within a range of allowable SNRs.

A high performance imaging system for diffuse optical tomography is disclosed. A dense grid utilizing sources, e.g., light emitting diodes (“LEDs”), that achieve high performance at high speed with a high dynamic range and low inter-channel crosstalk are complemented by a system of discrete, isolated receivers, e.g., avalanche photodiodes (“APDs”). The source channels have dedicated reconfigurable encoding control signals, and the detector channels have reconfigurable decoding, allowing maximum flexibility and optimal mixtures of frequency and time encoding and decoding. Each detector channel is analyzed by dedicated, isolated, high-bandwidth receiver circuitry so that no channel gain switching is necessary. The resulting improvements to DOT system performance, e.g., increased dynamic range and decreased crosstalk, enable higher density imaging arrays and provide significantly enhanced DOT image quality. A processor can be utilized to provide sophisticated three dimensional modeling as well as noise reduction.

The invention computes frequency-domain channel gains by compiling a set of estimated channel gains as a function of pilot sequences, a set of analytical channel gains variables, and a set of weighting coefficients variables. A plurality of weighting coefficients are computed as a function of time and frequency correlation functions, a noise correlation matrix, and pilot sequences. A weighting matrix is computed from the weighting coefficients. After receiving a training sequence from at least one transmitter, a received data matrix is computed from the training sequence. The weighting matrix and the received data matrix are used to compute the frequency-domain channel gains. The invention also provides a method for reducing the computational complexity of estimating the time and frequency response of at least one desired signal received by at least one antenna. Also, the time and frequency response of at least one desired signal received by at least one antenna can be both interpolated and predicted with the present invention.

Determining a compensated phase matrix for a multi-stimulus demodulation process is provided. A first drive line of a multi-stimulus sensing system is selected, and a stimulation signal is transmitted on the selected drive line. A channel gain resulting from the stimulation signal is measured from a received sense signal resulting from the stimulation signal. The measured channel gain is compared with a known channel gain to obtain an individual phase compensation for the selected drive line. A compensated phase matrix is formed of the individual phase compensation values for multiple drive lines.

Automatic white balancing and / or autoexposure as useful in a digital camera extracts color channel gains from comparisons of image colors with reference colors under various color temperature illuminants and / or extracts exposure settings from illuminance mean, illuminance variance, illuminance minimum, and illuminance maximum in areas of an image with a trained neural network.

The present disclosure relates to a method to determine a formation property of a subsurface formation. A downhole logging tool having two or more antennas, at least two of the antennas having a transversely-sensitive element and an axially-sensitive element is provided. Azimuthally-sensitive measurements are obtained using the antennas of the downhole logging tool. The measurements are fitted to a Fourier series having Fourier coefficients that include channel gains, if any. A DC component, a first harmonic component, and a second harmonic component are determined from the Fourier series, a measurement type is determined using the DC component, the first harmonic component, and / or the second harmonic component, and the formation property of the subsurface formation is determined using the determined measurement type.

A method of power amplifier predistortion that makes use of a compression detector circuit in a feedback loop in order to adapt the channel gain for changing transmitter behavior. By monitoring the compression behavior of the amplifier, the signal is scaled to compensate for gain and compression point variations in the power amplifier and transmitter, while keeping a predistortion correction function constant.

A bidirectional remote keyless entry (RKE) transponder comprises an analog front-end (AFE) having a programmable wake-up filter that predefines the waveform timing of the desired input signal, minimum modulation depth requirement of input signal, and independently controllable channel gain reduction of each of its three channels, X, Y, and Z. The wake-up filter parameters are the length of high and low durations of wake-up pulses that may be programmed in a configuration register. The wake-up filter allows the AFE to output demodulated data if the input signal meets its wake-up filter requirement, but does not output the demodulated data otherwise. The AFE output pin is typically connected to an external device for control, such as a microcontroller (MCU). The external device typically stays in low current sleep (or standby) mode when the AFE has no output and switches to high current wake-up (or active) mode when the AFE has output. Therefore, in order to keep the external control device in the low current sleep mode when there is no desired input signal, it is necessary to keep no output at the AFE output pin. This can be achieved by controlling the wake-up filter parameters, minimum modulation depth requirement of input signal, and channel gains of the AFE device. These features can reduce false-wake up of the bidirectional RKE transponder due to undesired input signals such as noise signals.

Certain embodiments of the invention may be found in a method and system for an improved user group selection scheme with finite-rate channel state information feedback for frequency division duplex (FDD) multiuser multiple-input-multiple-output (MIMO) downlink transmission. Aspects of the method may include selecting, from a plurality of users in a FDD multiuser communication system, a first user having a channel gain that is greater than a channel gain corresponding to a remaining portion of the plurality of users. A second user may be selected from the remaining portion of the plurality of users, based on a channel gain of the second user and orthogonality of the second user's channel direction with respect to the first user. The selected second user may have a channel gain that is greater than a channel gain corresponding to the remaining portion of the plurality of users.

Wireless terminals, e.g., mobile nodes, receive, identify, and measure broadcast signals from a plurality of cells. They determine relative transmission power relationships corresponding to the received measured signals and determine at least two channel gain ratios. A geographic area is determined corresponding to the obtained at least two channel gain ratios and information indicating the geographic region in which such gain ratios may be detected. Each cell's base station transmits broadcast signals, e.g., beacon signals, pilot signals, and / or assignment signals for one more carriers. Some base stations use multiple carriers at different power levels. Some adjacent cells use different power levels for the same carrier. This carrier diversity approach tends to reduce overall interference in the system, yet provides mobiles with a variety of different strength signals which may be monitored and which vary as a function of distance from the source transmitter.

An apparatus and method for determining a beamforming vector in a codebook-based transmission beamforming system are provided. In a feedback method for a receiver in a codebook-based transmission beamforming system, forthcoming channel values for a forthcoming period are generated using M present and previous channel estimates. Effective channel gains for all transmission beamforming vectors included in a codebook are calculated using the forthcoming channel values. A codebook index corresponding to the maximum effective channel gains is fed back to a transmitter.

Automatic white balancing and / or autoexposure as useful in a digital camera extracts color channel gains from comparisons of image colors with reference colors under various color temperature illuminants and / or extracts exposure settings from illuminance mean, illuminance variance, illuminance minimum, and illuminance maximum in areas of an image with a trained neural network.

Certain embodiments of the invention may be found in a method and system for an improved user group selection scheme with finite-rate channel state information feedback for frequency division duplex (FDD) multiuser multiple-input-multiple-output (MIMO) downlink transmission. Aspects of the method may include selecting, from a plurality of users in a FDD multiuser communication system, a first user having a channel gain that is greater than a channel gain corresponding to a remaining portion of the plurality of users. A second user may be selected from the remaining portion of the plurality of users, based on a channel gain of the second user and orthogonality of the second user's channel direction with respect to the first user. The selected second user may have a channel gain that is greater than a channel gain corresponding to the remaining portion of the plurality of users.

Wireless terminals, e.g., mobile nodes, receive, identify, and measure broadcast signals from a plurality of cells. They determine relative transmission power relationships corresponding to the received measured signals and determine at least two channel gain ratios. A geographic area is determined corresponding to the obtained at least two channel gain ratios and information indicating the geographic region in which such gain ratios may be detected. Each cell's base station transmits broadcast signals, e.g., beacon signals, pilot signals, and / or assignment signals for one more carriers. Some base stations use multiple carriers at different power levels. Some adjacent cells use different power levels for the same carrier. This carrier diversity approach tends to reduce overall interference in the system, yet provides mobiles with a variety of different strength signals which may be monitored and which vary as a function of distance from the source transmitter.

A multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) transceiving system is provided, in which an MIMO-OFDM receiver feeds back ordering information, such as the order of power intensities of reception signals of a plurality of reception antennas, to an MIMO-OFDM transmitter. The MIMO-OFDM transmitter arranges subcarriers, to which data symbols have been allocated, so that the subcarriers respectively correspond to a plurality of transmission antennas, according to the fed-back information. Thus, a specific substream can be transmitted via a transmission antenna having the greatest channel gain. Consequently, the probability of properly recovering the specific substream is greatly increased.

Certain embodiments of the invention may be found in a method and system for a simplified user group selection scheme with finite-rate channel state information feedback for frequency division duplex (FDD) multiuser multiple-input-multiple-output (MIMO) downlink transmission. Aspects of the method may include selecting, from a plurality of users, a first user having a channel gain that is greater than a channel gain corresponding to a remaining portion of the plurality of users. At least a second user may be selected from a portion of the remaining portion of the plurality of users. The selected at least the second user has a channel direction that may be approximately orthogonal to that of the first user. The channel gain may be defined by a quantized channel gain. A quantized channel direction of the selected first user may be determined for the selecting the at least the second user.

Provided with a method of performing power control in a CDMA mobile communication system, characterized by including the steps of: repeatedly updating information concerning the change of a channel state between a mobile station and a base station at regular intervals; varying a channel gain up / down time and / or a channel gain up / down delta adaptively based on the updated information; and adjusting the channel gain between the mobile station and the base station.

A method and system for dynamic rate switching via medium access channel layer signaling is disclosed, wherein data rates for high data rate channels are automatically shifted up or down based on a predetermined metric. In a preferred embodiment, data rates are automatically shifted up or down based on transmit channel gain required to maintain a required signal to noise ratio.

An apparatus for performing shade correction for a lens in an image sensor includes a gain profile extractor, a common profile calculator, a gain controller calculator, and a memory device. The gain profile extractor generates a respective channel gain profile for each of a plurality of color channels from image data. The common profile calculator generates a common profile from the channel gain profiles. The gain controller calculator generates a respective gain controller for each of the plurality of color channels from the common profile and the channel gain profiles. A memory device stores the common profile and the gain controllers.

A transmission power control apparatus in a mobile communication system comprises a base station manager adapted to control transmission power of base station channels, wherein the base station manager comprises a channel gain setting unit adapted to set a channel gain ration for each of a plurality of base station channels, the channel gain ratio being a ratio of transmission power of a base station channel to maximum transmission power of a base station, the base station manager further comprising a channel gain converting unit adapted to calculate a power value for each of the plurality of base station channels based on the corresponding channel gain ratio and to transmit the calculated power value to the base station. The transmission power control apparatus further comprises the base station adapted to control the transmission power of each of the plurality of base station channels based on the calculated power values.

A receiver for a multi-carrier CDMA system receives a signal transmitted having a known pilot sequence on plural sub-carriers. The system includes plural down-converters for down-converting the received signal to baseband signals. A delay and channel estimator correlates at least one of the baseband signals with a single wideband pilot signal, the single wideband pilot signal including all of the known pilot sequences, to produce an estimate of channel gain and multi-path delay. Plural demodulators, one for each of the plural sub carriers, are operatively coupled to the delay and channel estimator, each for demodulating one of the plural baseband signals using the estimate of channel gain and multi-path delay.

An efficient system and method for modulation and demodulation to achieve a high data rate using Bit-Interleaved Coded Modulation and OFDM uses either a coherent or a non-coherent transmission scheme using differential modulation. In order to maintain a high data rate impervious to sudden phase changes, a communication system uses an efficient constellation having multiple rings with different sizes and modulation / demodulation schemes utilizing this constellation. In power line communications, the channel gain information is obtained easily at a receiver (100) while the phase information is not. Thus, the communication system uses an absolute magnitude and differential phase coding for modulation and demodulation of the signals.

Determining a compensated phase matrix for a multi-stimulus demodulation process is provided. A first drive line of a multi-stimulus sensing system is selected, and a stimulation signal is transmitted on the selected drive line. A channel gain resulting from the stimulation signal is measured from a received sense signal resulting from the stimulation signal. The measured channel gain is compared with a known channel gain to obtain an individual phase compensation for the selected drive line. A compensated phase matrix is formed of the individual phase compensation values for multiple drive lines.

A method is provided for allocating resources in a base station (BS) of a mobile communication system. The method includes calculating a priority value of each sub-carrier for each mobile station (MS) according to a data rate required by each MS and an average channel gain for each MS, the priority value based on an average channel gain between MSs; and allocating the sub-carriers to a MS according to the priority value calculated for each sub-carrier for each MS.

Dislosed is an apparatus and method for erasure detection and soft-decision decoding in a cellular system receiver. In the present invention, a complex channel gain and a noise variance of a received symbol from a cellular system transmitter are estimated, and an erasure symbol (a symbol with high power interference) is detected by comparing a threshold value according to the estimated complex channel gain or noise variance with power of the received symbol. Log-likelihood ratios corresponding to constituent bits of the detected erasure symbols are allowed to be 0, and the log-likelihood ratios of the constituent bits of the other received symbols are calculated. A soft-decision decoding operation of received bits is performed with the calculated log-likelihood ratios.

A method and system for dynamic rate switching via medium access channel layer signaling is disclosed, wherein data rates for high data rate channels are automatically shifted up or down based on a predetermined metric. In a preferred embodiment, data rates are automatically shifted up or down based on transmit channel gain required to maintain a required signal to noise ratio.

A novel method and apparatus for improving transmit antenna weight tracking using channel vector element to element correlations in a wireless communication system is disclosed. The present channel autocorrelation tracking technique utilizes the observation that tracking can be improved when a channel gain vector contains correlated elements. In a first embodiment of the autocorrelation tracking technique, the present invention extracts a coarse gradient estimate by utilizing a perturbation vector autocorrelation matrix estimate and a perturbation autocorrelation matrix to update TxAA weight vectors accordingly. In a second embodiment of the channel autocorrelation tracking technique, the present invention extracts a coarse gradient estimate by utilizing eigendecompositions, perturbation vector autocorrelation matrix estimates, and perturbation autocorrelation matrices to update TxAA weight vectors accordingly. In a third embodiment of the channel autocorrelation tracking technique, the present invention reduces the phase change that can occur at receivers.

A transmitter and a receiver are disclosed herein that support transmit antenna diversity using space-time block coding in a wireless communication system. The transmitter produces symbol combinations containing, as their elements, input symbols, the inversions and conjugates of the symbols, and symbols obtained by rotating the phases of the symbols once, forms a matrix having symbols in at least two columns orthogonal to each other with the symbol combinations, and transmits the matrix. The receiver detects symbols that minimize maximum likelihood (ML) decoding metrics over all possible symbols using channel gains from transmit antennas to a receive antenna. Also, the receiver selects candidate symbols among all possible symbols according to the characteristics of transmitted modulation symbols and detects symbols that minimize the ML decoding metrics.

A resource allocation method in a multiuser-multiple-input multiple-output / orthogonal frequency division multiple access (MIMO / OFDMA) system. In the multiuser-MIMO / OFDMA system feedback information is received from terminals. A channel gain and a transmission rate for each user are determined using the feedback information. An average channel gain for each user is computed according to the channel gain. The average number of bits for each user is determined according to the average channel gain. The number of subchannels for each user is computed according to the average number of bits for each user. At least one subchannel is allocated to each user according to the number of subchannels for each user. A modulation scheme for each of the at least one subchannel is determined. The resource allocation method adaptively allocates subchannels and bits according to channel environment, thereby considerably improving frequency use efficiency as well as a power gain.