Signal transmission with symbol correction is disclosed. In one example, processing includes selection of one of known data and unknown data for each of symbols, as transmission data, while selecting a symbol of the known data for a reception side at one or both of timings of immediately before and immediately after selection of a symbol of unknown data for the reception side, modulation of each of the symbols of the selected transmission data, and transmission of a transmission signal obtained. Moreover, processing includes: reception of a transmission signal transmitted from a transmission side; and correction of a symbol of unknown data included in the received transmission signal on the basis of a symbol of known data included in the received transmission signal.

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 multimode receiving device configured to receive a standard Bluetooth data packet and a physical layer data packet with enhanced performance, can include: a receiving circuit configured to convert a received radio frequency signal to a baseband modulated signal; a demodulation circuit configured to select a demodulation scheme that conforms to a Bluetooth standard or one of a plurality of despread demodulation schemes, in order to demodulate the baseband modulated signal; and the plurality of despread demodulation schemes being configured to correspond to a plurality of predetermined spread-spectrum modulation schemes.

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.

A system for automatically detecting the PHY mode based on the incoming preamble is disclosed. The system includes a multimode demodulator, which includes a preamble detector and a demodulator. The preamble detector is used to determine when the preamble has been received and the PHY mode being used by the sending node. An indication of the PHY mode is supplied to the demodulator, which then decides the incoming bit stream in accordance with the detected PHY mode. In some embodiments, one demodulator, capable of decoding the bit stream in accordance with a plurality of PHY modes is employed. In other embodiments, the system includes a plurality of demodulators, where each is dedicated to one PHY mode.

A method of recovering information encoded by a modulated sinusoidal waveform having first, second, third and fourth data notches at respective phase angles, where a power of the modulated sinusoidal waveform is reduced relative to a power of an unmodulated sinusoidal waveform within selected ones of the first, second, third and fourth data notches so as to encode input digital data. The method includes receiving the modulated sinusoidal waveform and generating digital values representing the modulated sinusoidal waveform. A digital representation of the unmodulated sinusoidal waveform is subtracted from the digital values in order to generate a received digital data sequence, which includes digital data notch values representative of the amplitude of the modulated sinusoidal waveform within the first, second, third and fourth data notches. The input digital data is then estimated based upon the digital data notch values.

A C/N ratio detection circuit includes a voltage detector, an averaging section, a time variation range calculator, and a C/N ratio calculator. The voltage detector measures an input voltage of a signal. The averaging section calculates an average of the input voltage over a predetermined time. The time variation range calculator calculates a time variation range of the input voltage over the predetermined time. The C/N ratio calculator calculates a C/N ratio of the signal by using the average and time variation range of the input voltage.

Embodiments of the present invention provide a reference signal sending method, a reference signal receiving method, and an apparatus. A reference signal sending method includes: obtaining a reference signal sequence, where the reference signal sequence includes multiple bits and exclusive OR of every two bits separated by one bit in the multiple bits is 1; performing Gaussian Minimum Shift Keying GMSK modulation on the reference signal sequence; and sending a modulated reference signal sequence. In the embodiments of the present invention, a reference signal sequence is designed as a sequence in which exclusive OR of every two bits separated by one bit is 1, GMSK modulation is performed on the reference signal sequence, and the same reference signal sequence is used to perform channel estimation during GMSK demodulation. Compared with a case in which a pseudo random sequence is used as a pilot symbol, channel estimation accuracy is improved.

A communication system and method are disclosed for parallel processing of received signals to improve sensitivity of the system. Generally, the method includes demodulating a modulated signal in a first demodulator circuit and a second demodulator circuit in parallel. The first and second demodulated signals are then de-whitened, and a cyclic redundancy code (CRC) check performed on each. If the de-whitened first demodulated signal passes the CRC check a first packet included in the signal is sent to a central processing unit (CPU) for further processing. If the de-whitened second demodulated signal passes the CRC check, and the de-whitened first demodulated signal fails, a second packet included in the de-whitened second demodulated signal is transmitted to the CPU for further processing. In one embodiment, one of demodulator circuits is a GFSK demodulator operated in the phase domain and configured to use maximum likelihood sequence estimation. Other embodiments are also described.

Mobile device for receiving, demodulating and processing, from a cellular base station, a modulated spread spectrum signal into a demodulated spread spectrum signal. Modulating the received, demodulated and processed spread spectrum signal into a modulated Orthogonal Frequency Division Multiplexed (OFDM) signal and transmitting the OFDM modulated signal in a digital communications wireless Network. Processing, in a mobile device, a fingerprint signal for authenticating use of the mobile device, and processing a touch screen generated signal for controlling the mobile device. Processing in a mobile device a motion detector generated signal into a motion detector generated control signal for control of mobile device. Receiving, demodulating and processing in a mobile device a modulated location finder signal into a processed location finder signal. Generating and processing in a mobile device a photo and/or video signal into processed digital photo and/or video signal. Providing the processed photo and/or digital video signal with said processed location finder signal to a transmitter for transmission of digital video signal with the processed location finder signal.