A system and method for narrowband sinewave modulation. The system includes an input buffer for storing input digital data and a sub-periodic modulator for encoding the input digital data in a periodic waveform. The sub-periodic modulator encodes one or more bit values of the input digital data within each period of the periodic waveform. One or more digital-to-analog converters generate an encoded analog waveform from a digital representation of the periodic waveform wherein the encoded analog waveform is of a frequency f and a power P. The encoding is performed by the sub-periodic modulator such that any signal of frequency f resulting from the encoding is of a power P at least 50 dB less than power P, where f is offset from f by more than 25 Hz.

A data communications system and method having high spectral efficiency. The method includes encoding input digital data using a plurality of symbol waveforms. Each symbol waveform occupies a period of a composite encoded waveform and represents one or more bits of the input digital data. Each symbol waveform has a first elliptical segment and a second elliptical segment of opposite polarity. The encoding includes defining each symbol waveform so that (i) a zero crossing from the first elliptical segment to the second elliptical segment of the symbol waveform is different for each of the symbol waveforms, and (ii) an energy of the first elliptical segment of the symbol waveform is substantially equal to an energy of the second elliptical segment of the symbol waveform. An encoded analog waveform is generated, using a digital-to-analog converter, from a digital representation of the composite encoded waveform.

A system and method for encoding multi-bit features into sinusoidal waveforms at selected phase angles. The method includes receiving input digital data and encoding the input digital data in a sinusoidal waveform by modulating the sinusoidal waveform at selected phase angles within a period of the sinusoidal waveform, thereby creating a modulated sinusoidal waveform. An encoded analog waveform is generated, using a digital-to-analog converter, from a digital representation of the modulated sinusoidal waveform. The modulating includes forming a first data notch at a first phase angle of the selected phase angles wherein the first data notch includes a first plurality of transition features and subtends a first phase angle range about the first phase angle, the first plurality of transition features being representative of a first plurality of bit values included within the input digital data.

A system and method for waveform modulation includes encoding input digital data at selected phase angles of an unmodulated sinusoidal waveform. The encoding includes selectively reducing a power of the unmodulated sinusoidal waveform at the selected phase angles in accordance with bit values of the input digital data so as to respectively define first, second, third and fourth data notches in the modulated sinusoidal waveform. An encoded analog waveform is then generated from a digital representation of the modulated sinusoidal waveform. The encoding is performed so that energies associated with the first and third data notches are balanced and energies associated with second and fourth data notches are also balanced. Each of the energies corresponds to a cumulative power difference between a power of the unmodulated sinusoidal waveform and a power of the modulated sinusoidal waveform over a phase angle range subtended by one of the data notches.

A multi-carrier data communications system and method having high spectral efficiency. The method includes encoding input digital data at selected phase angles of a plurality of sinusoidal waveforms to create a plurality of modulated sinusoidal waveforms. An output analog waveform is generated where the output analog waveform includes a plurality of encoded analog communication signals corresponding to a plurality of digital representations of the plurality of modulated sinusoidal waveforms. The encoding is performed so that adjacent ones of the plurality of modulated sinusoidal waveforms are separated in frequency by less than 15 Hz and any sideband included within the output analog waveform is of a power at least 50 dB below a power of the encoded analog communication signal associated with the sideband.

A method and apparatus for receiving feedback information of a transmitter in a mobile communication system are provided. The method includes determining a parameter related to a first user signal; transmitting the first user signal based on the parameter related to the first user signal to a receiver; and receiving feedback information associated with the first user signal and an interference signal based on the first user signal.

Digital mobile communications devices and methods for mobile peer to peer direct communications. Processing a touch screen generated signal into a processed touch screen control signal for controlling mobile devices. Processing fingerprint signal for authenticating a user of a mobile device. Processing in a mobile device a motion detector generated signal into a motion detector generated control signal, for navigation control of mobile device. Modulation and demodulation, transmission and reception of one Orthogonal Frequency Division Multiplexed (OFDM) signals and conversion of the received OFDM signal into a different OFDM signal. Received spread spectrum signals from 3G or 4G cellular systems are converted into OFDM signals and transmitted in a wireless network, e.g. a Wi-Fi network. Received OFDM signals, received in a first RF frequency band, are demodulated and in a repeater mode are re-transmitted in a cellular system or network in a second OFDM radio frequency band. One or more receivers and demodulators for receiving demodulating and processing received signals into location finder information. A video camera in mobile device generates video signal and transmits video signal with location finder information signal.

A method of performing synchronization and frequency offset estimation for an input signal includes receiving an input signal through a wireless channel, and performing a frequency compensation operation on the input signal based on a reference signal to generate a compensated input signal. The reference signal corresponds to an access code associated with the input signal. The method includes determining a synchronization timing and a frequency offset for the input signal by comparing the reference signal with the compensated input signal.

A device includes a frequency offset (FO) compensation circuit coupled with a decoder, and a soft information measurement circuit. The frequency offset compensation circuit is configured to: (i) receive a continuous phase modulation (CPM) signal, (ii) adjust the CPM signal in a sampling window based on a frequency offset compensation value, and (iii) provide the adjusted CPM signal to the decoder. The decoder is configured to: (i) receive the adjusted CPM signal generated by the FO compensation circuit, (ii) decode the adjusted CPM signal to obtain one or more information symbols associated with the CPM signal, (iii) provide the one or more information symbols for soft information generation; and (iv) receive soft information provided by the soft information measurement circuit.

Disclosed is a method for recovering an original signal in a DS-CDMA system based on complexity reduction. In such a method, first, a partial derivative for rMLL is calculated by using a partial derivative generated by applying fast Fourier transform (FFT) to a reduced negative marginal log likelihood (rMLL) obtained by applying a law of log determinant to a Gaussian process regression (GPR) scheme used for the multi-user detection and thereafter, integrating stochastic gradient descent (SGD). Thereafter, the rMLL is calculated by using the partial derivative for the rMLL and a hyper-parameter is updated to a convergence point until an error gap is converged by repeated calculation of the rMLL. Next, a kernel function used for estimating a matched filter is calculated by using the hyper-parameter estimated through the convergence and the original signal for each of multi-users is recovered by using the kernel function.