7559results about "Multiple carrier systems" patented technology

A data-modulated ultra wideband transmitter that modulates the phase, frequency, bandwidth, amplitude and / or attenuation of ultra-wideband (UWB) pulses. The transmitter confines or band-limits UWB signals within spectral limits for use in communication, positioning, and / or radar applications. One embodiment comprises a low-level UWB source (e.g., an impulse generator or time-gated oscillator (fixed or voltage-controlled)), a waveform adapter (e.g., digital or analog filter, pulse shaper, and / or voltage variable attenuator), a power amplifier, and an antenna to radiate a band-limited and / or modulated UWB or wideband signals. In a special case where the oscillator has zero frequency and outputs a DC bias, a low-level impulse generator impulse-excites a bandpass filter to produce an UWB signal having an adjustable center frequency and desired bandwidth based on a characteristic of the filter. In another embodiment, a low-level impulse signal is approximated by a time-gated continuous-wave oscillator to produce an extremely wide bandwidth pulse with deterministic center frequency and bandwidth characteristics. The UWB signal may be modulated to carry multi-megabit per second digital data, or may be used in object detection or for ranging applications. Activation of the power amplifier may be time-gated in cadence with the UWB source thereby to reduce inter-pulse power consumption. The UWB transmitter is capable of extremely high pulse repetition frequencies (PRFs) and data rates in the hundreds of megabits per second or more, frequency agility on a pulse-to-pulse basis allowing frequency hopping if desired, and extensibility from below HF to millimeter wave frequencies.

An amplitude error compensating device comprises an amplitude correcting section for performing amplitude correction with respect to an in-phase component and a quadrature component of a complex signal obtained by quadrature demodulation, based on amplitude error information, and outputting a resultant amplitude-corrected complex signal, and an amplitude error detecting section for obtaining the amplitude error information, depending on amplitudes of an in-phase component and a quadrature component of the amplitude-corrected complex signal. The amplitude error detecting section comprises a power difference calculating section for obtaining as a power error a difference in power between the in-phase component and the quadrature component of the amplitude-corrected complex signal, a rotation detecting section for detecting a rotation of a signal point of the amplitude-corrected complex signal, an error information control section for outputting the power error when a rotation of the signal point has been detected, and 0 when a rotation of the signal point has not been detected, and a smoothing section for smoothing an output of the error information control section, and outputting the result as the amplitude error information.

An approach is provided for a method of encoding structure Low Density Parity Check (LDPC) codes. Memory storing information representing a structured parity check matrix of Low Density Parity Check (LDPC) codes is accessed during the encoding process. The information is organized in tabular form, wherein each row represents occurrences of one values within a first column of a group of columns of the parity check matrix. The rows correspond to groups of columns of the parity check matrix, wherein subsequent columns within each of the groups are derived according to a predetermined operation. An LDPC coded signal is output based on the stored information representing the parity check matrix.

The present invention provides a method and an apparatus may increase or extend the range of wireless communication cells for a given throughput in a downlink of a wireless communication system. When transmitting data in a downlink of a plurality of access point cells in a wireless local area network (WLAN), the range of the downlink may be increased for a given throughput under one or more radiated power constraints. The method includes providing a plurality of antennas at an access point to transmit the data to a wireless unit under at least one of a first and a second radiated power constraints. The method further includes using the plurality of antennas for beamforming over a group of sub-carriers subject to the first and / or second radiated power constraints. Under one or more radiated power constraints, a multiple antenna based beamforming may extend the range of a wireless communication for a user of a wireless unit that may be located within a coverage area across the plurality of access point cells of a Wi-Fi network associated with the WLAN. A joint beamforming optimized over all of sub-carriers may account for a European regulation restriction into at least one of an averaged and a spectral density Equivalent Isotropic Radiated Power (EIRP) constraint. In this way, an Orthogonal Frequency-Division Multiplexing (OFDM) based joint beamformer may provide a significant performance improvement and range extension.

Ultra Efficient Modulation-Demodulation (modem) and Transmitters-Receivers (transceivers) for high spectral efficient signal generation and processing methods and implementations. Embodiments include Clock Modulated (CM) and Shaped Clocked (SC) transceivers designated as Feher Keying (FK), Feher Quadrature Shift Keying (FQPSK) and Feher Quadrature Modulation (FQAM). In the FK modulator, clock converted and clock shaped signals are processed and generated. These are based on the input data signal patterns.

A communication system is disclosed that allows high data-rate transmission of data between components. N-bit parallel data is transmitted in K-frequency separated channels on the transmission medium so as to fully take advantage of the overall bandwidth of the transmission medium. As a result, a very high data-rate transmission can be accomplished with low data-bit transmission on individual channels. A transmitter system and a receiver system are described for the communication system.