Patent application number | Description | Published |
20080207260 | Private Mobility Management Enhancements - A method and apparatus described herein uses a mobility server to supplement the mobility management operations of a conventional mobile switching circuit (MSC). The mobility server receives mobility messages from a wireless terminal, and updates a location register associated with the MSC responsive to the received mobility messages. According to one exemplary embodiment, the mobility server has a pre-determined network address, such as a phone number, IP address, etc. The wireless terminal sends the mobility messages as user-plane messages to the pre-determined network address over a traffic data channel. In one exemplary embodiment, the mobility messages indicate the imminent loss of usable base station signals at an identified wireless terminal. For this embodiment, the mobility server may identify a satellite beam associated with the wireless terminal's location based on the received mobility messages, and update the location register accordingly. | 08-28-2008 |
20080316076 | Direct RF D-to-A Conversion - A modulator described herein provides digital modulation and direct digital-to-analog conversion capable of achieving 12-bit resolution or higher for high frequency signals. The modulator comprises a digital modulator, conversion circuit, and multiplexer. The digital modulator generates a plurality of sample streams at a plurality of different sample phases that collectively represent a desired modulated digital carrier waveform modulated by a digital input signal. The conversion circuit converts the sample streams into a plurality of continuous analog signals. The multiplexer multiplexes the analog signals together to generate a modulated analog carrier signal representative of the desired modulated digital carrier waveform. | 12-25-2008 |
20090023462 | Signal Waveform Construction for Position Determination by Scrambled Conical - A method and apparatus for determining a mobile station's location using an antenna beam that traverses a scan pattern is described herein. In one embodiment, a device transmits/receives a signal as a position of a transmission/reception antenna beam traverses the scan pattern in a non-sequential order. A strength of the received signal is measured at a plurality of the beam positions. After reordering the signal strength measurements, the mobile station location relative to a nominal center of the beam is determined based on the reordered signal strength measurements. Another embodiment uses signals having different frequency components that are transmitted or received in beams executed in different scan patterns. In this embodiment, signal strength measurements associated with different frequency components are jointly processed to determine a combined correlation. The relative mobile station location is determined based on the combined correlation. | 01-22-2009 |
20090160576 | Passive Fourier Transform Circuits and Butler Matrices - The coupling circuit described herein comprises passive analog components for coupling a transceiver to an antenna, such as an antenna array. The coupling circuit transforms an input signal into an appropriate format for each element of the antenna array. The coupling circuit comprises a coupling network having a plurality of inputs and a plurality of outputs. The inputs provide quadriphase versions of at least one input signal. In one embodiment, the coupling circuit performs a Discrete Fourier Transform (DFT) on the input signal. In another embodiment, the coupling circuit performs a Fast Fourier Transform (FFT) on the input signal. In still another embodiment, the FFT performed by the coupling circuit implements a Butler matrix. | 06-25-2009 |
20090213922 | Method and Apparatus for Efficient Multi-Symbol Detection - Where two or more multi-valued digital data symbols are modulated so that they overlap after passing through a channel, forming a combined signal, a receiver receives the combined signal and forms detection statistics to attempt to recover the symbols. Where forming detection statistics does not completely separate the symbols, each statistic comprises a different mix of the symbols. A receiver determines the symbols which, when mixed in the same way, reproduce or explain the statistics most closely. For example, the receiver hypothesizes all but one of the symbols and subtracts the effect of the hypothesized symbols from the mixed statistics. The remainders are combined and quantized to the nearest value of the remaining symbol. For each hypothesis, the remaining symbol is determined. A metric is then computed for each symbol hypothesis including the so-determined remaining symbol, and the symbol set producing the best metric is chosen as the decoded symbols. | 08-27-2009 |
20090225899 | Compensation of Diagonal ISI in OFDM Signals - A method and apparatus for compensating for ISI is described herein. A transmitter and receiver work together to develop pulse shaped OFDM symbols with reduced inter-channel ISI between pulse-shaped OFDM symbols transmitted on different sub-carriers at the same time, and inter-block ISI between pulse-shaped OFDM symbols transmitted on the same sub-carrier at different times. In addition, a pre-compensation element in the transmitter and/or a post-compensation element in the receiver compensate for diagonal ISI occurring between pulse-shaped OFDM symbols transmitted on different sub-carriers at different times. | 09-10-2009 |
20090253385 | System and Method for Adaptive Antenna Impedance Matching - Methods and apparatus are disclosed for automatically adjusting antenna impedance match in a wireless transceiver employing phase-amplitude modulation. According to some embodiments of the invention, a wireless transceiver comprises a transmitter circuit and a receiver circuit connected to the antenna by a transmit/receive duplexer. An electronically adjustable matching network is located between the transmitter output and the antenna. To control the adjustable matching network, a directional coupler is located between the transmitter output and the matching network to separate transmit signals reflected from the antenna system, including the antenna, the matching network and the T/R duplexer. The reflected transmit signals are routed to the receiver circuit, which digitizes the reflected signal and determines an antenna reflection coefficient based on the digitized reflected signal and the modulation signal used to create the transmit signal. The complex antenna reflection coefficient is used to determine any adjustment needed to the antenna matching network. | 10-08-2009 |
20090325509 | Methods and Apparatus for Reducing Own-Transmitter Interference in Low-IF and Zero-IF Receivers - Circuits and methods are disclosed for reducing interference from transmitter leakage in a radio transceiver. An exemplary method for reducing interference from transmitter leakage in a radio transceiver comprises downconverting, filtering, and sampling a radio frequency signal comprising a desired signal and a transmitter leakage signal to obtain a sampled signal of interest. The method further comprises generating a sampled distortion signal estimate that estimates one or more distortion products of the transmitter leakage signal, such as a squared amplitude obtained from a square-law device or corresponding digital function. Finally, the method comprises combining the sampled distortion signal estimate with the sampled signal of interest to obtain interference-reduced signal samples. In some embodiments, this may comprise correlating the sampled distortion signal estimate with the sampled signal of interest to determine a scaling factor, scaling the sampled distortion signal estimate with the scaling factor, and subtracting the scaled distortion signal estimate from the sampled signal of interest to obtain the interference-reduced signal samples. | 12-31-2009 |
20090325518 | Methods and Apparatus for Suppressing Strong-Signal Interference in Low-IF Receivers - Circuits and methods are disclosed for compensating for received signal distortion caused by non-linearities in the receiver circuitry. An exemplary receiver circuit includes a distortion waveform generator configured to approximate one or more non-linear response characteristics of a downconverter circuit used to downconvert the received radio frequency signal. The estimated distortion waveform thus produced is filtered, using a filter or filters substantially similar to those used for filtering an intermediate frequency signal that includes the desired signal and non-linear distortion products caused by strong interfering signals. The filtered estimated distortion waveform and the intermediate frequency are sampled, to obtain a sampled distortion signal and a sampled signal of interest. The sampled distortion signal is scaled, and subtracted from the sampled signal of interest to obtain reduced-interference signal samples. In some embodiments, the scaling factor is determined by correlating the sampled signal of interest with the sampled distortion signal. | 12-31-2009 |
20100034404 | VIRTUAL REALITY SOUND FOR ADVANCED MULTI-MEDIA APPLICATIONS - The method and apparatus described herein generates realistic audio for a virtual reality simulation based on the position (location and orientation) of a participant's head. The audio may be generated based on independent and dependent audio profiles. The independent audio profile represents the participant-independent propagation of sound from a virtual source to each of one or more virtual objects in the simulation. The dependent audio profile represents the propagation of the sound from each of the one or more virtual objects to the head or ears of the participant based on a position of the participant's head or ears. An audio processor generates the desired audio signal at the head of the participant by combining the dependent and independent audio profiles to determine a total audio profile for the virtual source, and filtering an audio wave corresponding to the virtual source based on the total audio profile. | 02-11-2010 |
20100098042 | USING THE SAME MULTIPLEXED RADIO RESOURCE FOR PILOT AND INFORMATION SIGNALS - A method and apparatus for using the same multiplexed radio resource to simultaneously transmit a pilot sequence and an information signal is described herein. After traveling through a multi-path propagation channel, a receiver receives the transmitted pilot and information signals, correlates the received signal with the known pilot sequence to determine one or more correlation values, and estimates the multi-path propagation channel based on the correlation values. The receiver uses the channel estimates to process the received signal to remove the pilot sequence from the information signal. By using the same multiplexed radio resource to transmit both the pilot sequence and the user information signal, the present invention enables more radio resources to be allocated to the information signal without compromising pilot-based channel estimation, and provides more regular access to the transmitted pilot sequence at the receiver. | 04-22-2010 |
20100159837 | Own Transmitter Interference Tolerant Transceiver and Receiving Methods - Circuits and methods are disclosed for reducing interference from transmitter leakage in a radio transceiver. An exemplary method for reducing interference from transmitter leakage in a radio transceiver comprises downconverting, filtering, and sampling a radio frequency signal comprising a desired signal and a transmitter leakage signal to obtain a sampled signal of interest. The method further comprises generating a sampled distortion signal estimate that estimates one or more distortion products of the transmitter leakage signal, such as a squared amplitude obtained from a square-law device or corresponding digital function. Further, the method comprises dividing the sampled distortion signal estimate and the sampled signal of interest into a plurality of frequency channels. Finally, for a selected number of frequency channels, the method comprises combining the sampled distortion signal estimate for a frequency channel with the corresponding sampled signal of interest for the same frequency channel to obtain interference-reduced signal samples for the frequency channel. | 06-24-2010 |
20100159858 | Strong Signal Tolerant OFDM Receiver and Receiving Methods - Circuits and methods are disclosed for compensating for received signal distortion caused by non-linearities in wideband receivers. An exemplary receiver includes a distortion waveform generator configured to approximate non-linear response characteristics of a downconverter circuit used to downconvert the received radio frequency signal. The resulting estimated distortion waveform is filtered, using filter(s) substantially similar to those used for filtering an intermediate frequency signal that includes the desired signal and non-linear distortion products caused by strong interfering signals. The filtered estimated distortion waveform and intermediate frequency signal are sampled, to obtain a sampled distortion signal and a sampled signal of interest. The sampled distortion signal and the sampled signal of interest are divided into a plurality of frequency channels. For a selected number of frequency channels, the sampled distortion signal for a frequency channel is scaled, and subtracted from the corresponding sampled signal of interest for the same frequency channel to obtain reduced-interference signal samples for the frequency channel. | 06-24-2010 |
20100226416 | Compensating Pre-Filter for an OFDM Transmitter - A method and apparatus for reducing group delay and/or amplitude errors applied to a transmission signal by one or more transmission filters is described herein. The present invention characterizes the errors introduced by one or more transmission filters relative to a desired frequency response, e.g., the group delay and/or amplitude errors relative to a flat group delay and flat amplitude, respectively. Based on the errors, the present invention pre-compensates the digital frequency domain samples used to generate the transmission signal. In so doing, the present invention reduces the errors in the filtered transmission signal without placing limits on the design of the transmission filters. | 09-09-2010 |
20100226448 | CHANNEL EXTRAPOLATION FROM ONE FREQUENCY AND TIME TO ANOTHER - An improved channel estimation technique is provided herein that determines accurate scatterer parameters for the scattering objects in the wireless channel, and extrapolates the scatterer parameters in both time and frequency to characterize the scattering objects for a different time and a different frequency. In one embodiment, a wireless device determines scatterer parameters that characterizes the scattering objects of a reception channel, and extrapolates the scatterer parameters in both time and frequency to predict the scatterer parameters for a future time and frequency, e.g., a future transmission time and frequency. | 09-09-2010 |
20100226458 | OFDM Spectral Control - A method and apparatus for configuring a variable filter in an OFDM transmitter based on the number of subcarrier frequencies selected for the input data block is described herein. An exemplary OFDM transmitter comprises a control unit, OFDM modulator, and variable filter. The control unit selects the number of subcarriers for the input data block, and configures one or more filter properties for the variable filter based on the selected number of subcarriers. The modulator, which has a size greater than the selected number of subcarriers, pads an input data block generated for the selected number of subcarriers to generate an expanded data block having a size equal to the size of the modulator, and modulates the expanded data block to generate an OFDM signal. The filter, as configured by the control unit, filters the OFDM signal. | 09-09-2010 |
20100248651 | Antenna Matching for MIMO Transceivers - A multiple antenna system is described herein that mitigates the negative effects of mutually coupled antennas on the connected transmitters and/or receivers. The antenna system comprises a directional coupler and two or more antennas. The directional coupler comprises multiple communication ports that each connect to corresponding antenna ports. The connection ports each connect to a different transmitter, receiver, or transceiver. A transmission line connects each antenna port to an antenna. The lengths of the transmission lines and the coupling factor of the directional coupler are selected to decouple the communication ports of the directional coupler. More particularly, the coupling factor and the transmission line lengths are selected so that antenna crosstalk signals caused by mutual coupling between the antennas and the coupled signals produced by the directional coupler have the same magnitude but opposite phase at the communication ports of the directional coupler. | 09-30-2010 |
20100248664 | DIVERSITY RECEIVERS AND METHODS FOR RELATIVELY-DELAYED SIGNALS - Methods, software and apparatuses for decoding received delayed path signals are described. A receiver receives a signal via different paths with relative delay, e.g., on the same frequency channel. The signal is sampled at at least one sample per symbol. A channel estimator determines channel coefficients associated with the channel over which the signals were transmitted. A processor selects samples that include a dependence on a particular symbol being decoded and computes an error metric for each possible value of the particular symbol, for combinations of hypothesized future symbol values on which the selected samples depend, and for single values of previous symbols on which the selected samples depend. Error metrics calculated for each symbol are stored in memory. A soft symbol is generated based on said signal samples from the sampler, the channel coefficients and estimates of symbols computed. | 09-30-2010 |
20100309994 | MOBILE RADIO CHANNEL ESTIMATION - The method described herein characterizes scattering objects in a wireless channel. Broadly, the present invention determines non-equally spaced path delays and Doppler parameters for a plurality of scattering objects in a wireless channel. More particularly, a frequency-to-time transform applied to a plurality of OFDM pilot samples received over a plurality of OFDM symbol periods generates a set of non-equally spaced path delays and a set of associated complex delay coefficients. Further, a time-to-frequency transform applied to the complex delay coefficients determined for one path delay over multiple OFDM symbol periods generates a set of Doppler parameters comprising a plurality of non-equally spaced Doppler frequencies and their corresponding scattering coefficients for that path delay. | 12-09-2010 |
20100311350 | CONTINUOUS SEQUENTIAL SCATTERER ESTIMATION - The present invention uses newly received signal samples to update previously determined scatterer parameters, and therefore, reduces the processing effort required for characterizing scattering objects in a wireless channel. Broadly, the present invention determines a first set of scatterer parameters based on signal samples derived from signals received during one or more previous time intervals, and determines an updated set of scatterer parameters for a subsequent time interval based on the first set of scatterer parameters and the new signal samples. In one exemplary embodiment, the receiver uses a continuous sequential update process, e.g., a per-symbol-period inverse Prony process, to update the scatterer parameters. In another exemplar embodiment, the receiver uses an integrated Doppler approach to update the scatterer parameters. | 12-09-2010 |
20120281444 | SOLAR ENERGY CONVERSION AND UTILIZATION SYSTEM - A 1, 2 or 3-phase DC to AC converter system for reducing the cost of solar energy installations achieves cost reduction by eliminating low-frequency power transformers. One DC input polarity is selectively switched to an output terminal when the instantaneous AC output from a second output terminal is desired to be of the opposite polarity, while the other DC input polarity is used to form an approximation to a segment of a sine wave of the desired polarity at the second output terminal. A common-mode AC signal is thereby created on the balanced DC input lines at a frequency which is a multiple of 1, 2 or 3 times the AC output frequency and which is useful for detecting ground faults in the DC circuit. | 11-08-2012 |
20130028041 | Memory Compression - Exemplary embodiments comprise memory for storing the look-up table values. One exemplary memory comprises a decoder, an encoder, and one or more patterns of crisscrossed interconnect lines that interconnect the encoder with the decoder. The patterns of crisscrossed interconnection lines may be implemented on one or more planar layers of conductor tracks vertically interleaved with isolating material. | 01-31-2013 |
20130057997 | Potential Arc Fault Detection and Suppression - A wiring fault detector adapted specifically to address the requirement for arc fault protection specified in National Electrical Code (2011) article 690.11 comprises running at least one additional wire in parallel with the power conductors to be protected, thereby allowing evaluation at the location of a fault detector of an electrical parameter indicative of conductor integrity along its whole length. | 03-07-2013 |
20140084687 | SOLAR ENERGY CONVERSION AND UTILIZATION SYSTEM - An improved solar energy utilization system is described based on the use of a smart load center which can automatically select the use of utility power or solar-derived power independently for each of a number of load circuits based on availability of utility and solar power, preset user priorities, battery charge status, time of day, instantaneous consumption, historical consumption patterns and weather forecasts. | 03-27-2014 |
20140270115 | Electronic Message Aggregation and Sharing System and Apparatus - In one aspect of the invention, a communications device is described to include novel software for aggregating voice and other messages from various communications media and presenting the user with a display of same, ordered by medium, date of receipt, source etc. The software also comprises a user-friendly man-machine interface for forwarding the messages from one medium to another, including making such messages available to members of social websites. In a second aspect of the invention, a server computer is described, including software to receive, organize and store said messages in digital form, with the participation of the user's communication device in one mode and automatically without the participation of the user's device in another mode. The server comprises software that generates links to selected stored messages that the user can post on the Web. When such a link is opened by a web browser, the selected message is made available to the browser and the opportunity to display revenue-generating advertisements to all who access the message is simultaneously created. | 09-18-2014 |
20140355775 | WIRED AND WIRELESS MICROPHONE ARRAYS - An acoustic noise canceling microphone arrangement and processor that uses a principal microphone and other microphones that may be incidentally or deliberately located in the vicinity of the principal microphone in order to derive an audio signal of enhanced signal-to-background noise ratio. In one implementation, the principal and incidental microphones comprise the microphone built into a mobile phone and the microphone built into a Bluetooth headset. | 12-04-2014 |
20150043110 | Potential Arc Fault Detection and Suppression - A wiring fault detector adapted specifically to address the requirement for arc fault protection specified in National Electrical Code (2011) article 690.11 comprises running at least one additional wire in parallel with the power conductors to be protected, thereby allowing evaluation at the location of a fault detector of an electrical parameter indicative of conductor integrity along its whole length. | 02-12-2015 |