This document describes techniques for performing non-coherent demodulation of a differentially modulated signal in a drift robust manner. A differentially modulated signal, including a plurality of symbols, may be received. Non-coherent demodulation of the differentially modulated signal may be performed. The non-coherent demodulation may include performing noise prediction using a high-pass filtered estimated error signal associated with the differentially modulated signal. In some embodiments, frequency offset estimation to reduce frequency offset of the differentially modulated signal may also be performed as part of the non-coherent demodulation.

An embodiment of the present invention relates to an ultra low power wideband asynchronous binary phase shift keying (BPSK) demodulation method and a circuit configuration thereof. The ultra low power wideband asynchronous BPSK demodulation circuit comprises a sideband division and upper sideband signal delay unit dividing a modulated signal into an upper sideband and a lower sideband by a first order high-pass filter and a first order low-pass filter; a data demodulation unit latching, through a hysteresis circuit, a signal generated by a difference between the analog signals in which a phase difference between the delayed upper sideband analog signal and the lower sideband analog signal is aligned at 0, so as to demodulate digital data; and a data clock recovery unit for generating a data clock by using a signal digitalized from the lower sideband analog signal through a comparator and a data signal.

This document describes techniques for performing non-coherent demodulation of a differentially modulated signal in a drift robust manner. A differentially modulated signal, including a plurality of symbols, may be received. Non-coherent domodulation of the differentially modulated signal may be performed. The non-coherent demodulation may include performing noise prediction using a high-pass filtered estimated error signal associated with the differentially modulated signal. In some embodiments, frequency offset estimation to reduce frequency offset of the differentially modulated signal may also be performed as part of the non-coherent demodulation.

Methods and systems for I/Q mismatch calibration and compensation for wideband communication receivers may comprise receiving a plurality of radio frequency (RF) channels, downconverting the received plurality of received RF channels to baseband frequencies, determining and removing average in-phase (I) and quadrature (Q) gain and phase mismatch of the downconverted channels, determining a phase and amplitude tilt of the downconverted channels with removed average I and Q gain and phase mismatch, and compensating for said phase and amplitude tilt I and Q gain and phase mismatch of the downconverted channels. The determined phase tilt may be compensated utilizing a phase tilt correction filter, which may comprise one or more all-pass filters. The average I and Q gain and phase mismatch may be determined utilizing a blind source separation (BSS) estimation algorithm.

A wireless communication device includes a radio frequency antenna a transceiver. The transceiver includes a receiver having a switching architecture configured to generate a plurality of output phases within a local oscillator period based on the filtered RF signal and a respective plurality of local oscillator signals. The plurality of output phases can be organized into at least K groups where K is an integer of four or greater, and each nth group of the K groups includes nth and (n+K)th output phases of the plurality of output phases. The receiver can difference the nth and (n+K)th output phases of each respective group of the K groups, resulting in gain-added output phases.

Maximum likelihood bit-stream generation and detection techniques are provided using the M-algorithm and Infinite Impulse Response (IIR) filtering. The M-Algorithm is applied to a target input signal X to perform Maximum Likelihood Sequence Estimation on the target input signal X to produce a digital bit stream B, such that after filtering by an IIR filter, the produced digital stream Y produces an error signal satisfying one or more predefined requirements. The predefined requirements comprise, for example, a substantially minimum error. In an exemplary bit detection implementation, the target input signal X comprises an observed analog signal and the produced digital stream Y comprises a digitized output of a receive channel corresponding to a transmitted bit stream. In an exemplary bit stream generation implementation, the target input signal X comprises a desired transmit signal and the produced digital stream Y comprises an estimate of the desired transmit signal.

Software Digital Front End (SoftDFE) signal processing techniques are provided. One or more digital front end (DFE) functions are performed on a signal in software by executing one or more specialized instructions on a processor to perform the one or more digital front end (DFE) functions on the signal, wherein the processor has an instruction set comprised of one or more of linear and non-linear instructions. A block of samples comprised of a plurality of data samples is optionally formed and the digital front end (DFE) functions are performed on the block of samples. The specialized instructions can include a vector convolution function, a complex exponential function, an x.sup.k function, a vector compare instruction, a vector max( ) instruction, a vector multiplication instruction, a vector addition instruction, a vector sqrt( ) instruction, a vector 1/x instruction, and a user-defined non-linear instruction.

Methods and apparatus are provided for direct synthesis of RF signals using maximum likelihood sequence estimation. An RF digital RF input signal is synthesized by performing maximum likelihood sequence estimation on the digital RF input signal to produce a digital stream, such that after filtering by a prototype filter the produced digital stream produces a substantially minimum error. The substantially minimum error comprises a difference between a digital output of the prototype filter and the digital RF input signal. The digital stream is substantially equal to the input digital RF signal. The digital stream can be applied to an analog restitution filter, and the output of the analog restitution filter comprises an analog RF signal that approximates the digital RF input signal.

In order to efficiently compensate for effects of the Doppler shift, a receiving device includes a Doppler estimator that estimates a Doppler-shift frequency fdc of a received signal. A multiplier and an LPF detect the received signal based on a carrier frequency fc of the received signal and the Doppler-shift frequency fdc estimated by the Doppler estimator 11. A timing corrector corrects a timing T for extracting symbols of the received signal after detection by the LPF so as to track the Doppler shift. A symbol extractor extracts received symbols from the received signal after detection by the LPF at a timing corrected by the timing corrector. An adaptive equalizer estimates and determines symbols from the received symbols extracted by the symbol extractor.

A base station apparatus of mobile communication system is provided, including an antenna system including first antenna for transceiving signals for a first path among MIMO paths, and a second antenna for transceiving signals for a second path among the MIMO paths, a first duplexer including transmission filter for processing the transmitted signal of first path and reception filter for processing the received signal of second path, a second duplexer including reception filter for processing the received signal of first path and transmission filter for processing the transmitted signal of second path, and a path change unit for providing the transmitted signal provided from the first duplexer to the first antenna and the received signal provided from the first antenna to the second duplexer and to provide the transmitted signal from the second duplexer to the second antenna and the received signal from the second antenna to the first duplexer.