Abstract: Radio frequency (RF) receivers having whitened digital clocks and related methods are disclosed. Disclosed embodiments generate whitened clocks having random variations that are used to operate digital processing blocks so that interference created by the whitened clocks is seen as white noise within the received RF signal spectrum. RF input signals are received by RF front-ends (RFFEs) that output analog signals associated with channels within the RF input signals. These analog signals are converted to digital information and processed by digital receive path circuitry that outputs digital data associated with the channel. The digital receive path circuitry includes a whitened clock generator that generates a whitened clock having random variations and which a digital processing block that operates based upon the whitened clock. Further, the RFFE and the digital receive path circuitry are located within a single integrated circuit.

Abstract: Apparatus and methods for channel estimation in time division synchronous code division multiple access (TD-SCDMA) based on a signal received from one or more Node Bs include determining least squares channel metric estimates based on the received signal, identifying signal taps and noise taps in a tapped delay line channel estimate based on at least one of temporal correlations of the least squares channel metric estimates or composite hypothesis testing on the least squares channel metric estimates, and updating an interference buffer based on the signal taps and the noise taps.

Abstract: Apparatus and methods for channel estimation include determining two streams corresponding to odd and even samples of a received signal that is sampled at a first chip rate, performing least squares successive interference cancellation on each of the two streams to obtain odd and even raw channel estimates, interlacing the odd and even raw channel estimates to obtain interlaced channel estimates, interpolating additional samples in the interlaced channel estimates to create higher chip rate channel estimates, identifying a first set of tap positions based on the higher chip rate channel estimates, applying matching pursuit to the first set of tap positions to identify a second set of tap positions, wherein the second set of tap positions includes fewer tap positions than the first set of tap positions, and determining a third set of tap positions by clustering each tap position included in the second set of tap positions.

Abstract: A method and apparatus for compensation of noise in a Radio Frequency Identification (RFID) device through modulation of a received signal is described. The method includes determining an amplitude signal proportional to an amplitude of a transmitter signal and associated noise; processing the amplitude signal to derive a correction signal; and modulating a received signal during a receive period with the correction signal to substantially remove the associated noise from the received signal. An RFID device and an RFID transceiver integrated circuit (IC) are also described.

Abstract: Apparatus and methods for channel estimation includes determining two streams corresponding to odd and even samples of a received signal that is sampled at a first chip rate, performing least squares successive interference cancellation on each of the two streams to obtain odd and even raw channel estimates, interlacing the odd and even raw channel estimates to obtain interlaced channel estimates, interpolating additional samples in the interlaced channel estimates to create higher chip rate channel estimates, identifying a first set of tap positions based on the higher chip rate channel estimates, and applying matching pursuit to the first set of tap positions to identify a second set of tap positions, wherein the second set of tap positions includes fewer tap positions than the first set of tap positions.

Abstract: A system and method for analog self-interference cancellation that includes receiving an RF transmit signal of a full-duplex radio; frequency downconverting the RF transmit signal to an IF transmit signal; transforming the IF transmit signal into an IF self-interference signal using an IF analog self-interference cancelling circuit; frequency upconverting the IF self-interference signal to an RF self-interference signal; and combining the RF self-interference signal with an RF receive signal of the full-duplex radio.

Abstract: Embodiments are provided for a cooperative cross-tier precoding (CTP) and intra-tier precoding (ITP) scheme for two-tier networks. The cooperative precoding scheme allows exploitation of extra transmit dimensions at the second-tier network, thereby increasing the achievable throughput at the second-tier network. The embodiments allow significant increase in throughput of the second-tier network due to both CTP between the second-tier network and the first-tier network, and efficient ITP between the second-tier network transmitters. The increase in transmit dimension allows for efficient linear inra-tier precoding, which significantly reduces the intra-tier interference. A processor coupled to the second-tier network transmitters is configured to perform CTP of transmit signals in the second-tier network for cancelling signal interference from the second-tier network transmitters to a first-tier network receiver, thereby generating CTP matrix information.

Abstract: A receiver employs low-rate processing to synthesize the effect of high-rate interference in a received multi-rate signal. Each high-rate subchannel is analyzed on its low-rate descendents to produce symbol estimates for each low-rate symbol interval. The symbol estimates are applied to low-rate descendent subchannels, which are then combined to synthesize the effects of the high-rate interference. An interference canceller processes the synthesized interference with the received signal for producing an interference-cancelled signal. Alternatively, analogous steps may be applied at high-rate to analyze, synthesize, and cancel the effects of low-rate interference in a multi-rate signal.

Abstract: An image rejection (IR) circuit is configured to receive a complex signal from a radio frequency (RF) mixer, where the complex signal includes an in-phase signal portion and a quadrature signal portion. This IR circuit may include: an in-phase path to remove first mismatch information from the in-phase signal portion and associated with at least one in-phase multi-tap filter; a quadrature path to remove second mismatch information from the quadrature signal portion and associated with at least one quadrature multi-tap filter; and a correlation unit to independently update each of the multiple taps of the in-phase multi-tap filter and the quadrature multi-tap filter according to a priority scheme.

Abstract: A method of frequency-domain filtering is provided that includes a plurality of filters, the plurality of filters including at least one constrained filter(s) W=I, I and at least one unconstrained filter(s) W=1,K? The method includes cascading the W k=i,K unconstrained filter(s). A single constraint window C is applied to the cascaded W=i,K unconstrained filter(s). The W=1,I constrained filter(s) are cascaded with the constrained cascaded Wk=1,K unconstrained filter(s) to form a resulting filter Wll=C(W 1{circle around (x)} . . . {circle around (x)} W){circle around (x)} W . . . W. The frequency domain representation of the single constraint window C may be based, at least in part, on a time domain representation of a single constraint window C that has been circularly shifted such that the frequency domain representation of the constraint window matches a property of the frequency domain representation of the cascaded W=1,K unconstrained filters.

Abstract: A wireless communication receiver includes a first signal processing block, a phase noise compensation apparatus, and a second signal processing block. The first signal processing block is arranged for generating a first processed output by processing a reception signal, wherein the first signal processing block includes a channel estimation unit arranged for performing channel estimation. The phase noise compensation apparatus is arranged for receiving the first processed output and generating a second processed output by performing phase noise compensation according to the received first processed output. The second signal processing block is arranged for receiving the second processed output and processing the received second processed output.

Abstract: Peak-to-average ratio reduction is achieved by detecting peaks in an original analog signal that exceed a given threshold. Segments of the original analog signal containing such peaks are treated (e.g., by attenuation) and a composite analog signal is assembled that includes treated and untreated segments of the original analog signal. The composite analog signal is processed to perform analog-to-digital conversion to generate a composite digital signal. Segments of the composite digital signal corresponding to the treated segments of the original analog signal are reverse-treated or otherwise treated again to undo treatment of the segments of the original analog signal. A final output digital signal is generated that corresponds to the original analog signal in digital form.

Abstract: A method for calibrating mismatches of an in-phase signal path and a quadrature signal path of a transmitter, including: additionally configuration at least one mixer calibration coefficient at a transmitting part of the transmitter; obtaining at least one mixer testing signal from the transmitting part via loopback for spectrum analysis to derive at least one mixer spectrum analysis result; adjusting the mixer calibration coefficient of the transmitting part according to the mixer spectrum analysis result; and additionally utilizing an in-phase signal path finite impulse response filter and a quadrature signal path finite impulse response filter to calibrate mismatches between a low pass filter of the in-phase signal path of the transmitting part of the transmitter and a low pass filter of the quadrature signal path of the transmitting part of the transmitter. A similar mismatch calibration operation may be applied to a receiver.

Abstract: This disclosure presents a receiver apparatus (10) and corresponding method that advantageously use ISI-canceling combining weights, as are generated for ISI suppression in the receiver's data signal combining operations, to suppress the effects of ISI from determinations of receiver frequency error. Such suppression yields more accurate receiver frequency error determination and, correspondingly, improved receiver frequency error compensation.

Abstract: Repeatedly: pre-processing a received signal using feedback to obtain a pre-processed signal, the feedback being based on a previous signal, the previous signal being received prior to the received signal; evaluating at least one of a quality of a demodulated signal and a quality of a decoded signal, the demodulated signal being obtained from the pre-processed signal by demodulating, the decoded signal being obtained by decoding the demodulated signal; deciding if the respective at least one of the quality of the demodulated signal and the quality of the decoded signal is sufficient; selecting neither or one of the demodulated signal and the decoded signal as a selected signal based on the at least one of the quality of the demodulated signal and the quality of the decoded signal for which it is decided whether or not the quality is sufficient; and updating the feedback based on the selected signal.

Abstract: Techniques for handling fingers with large delay spread through utility optimization are described. A first signal may be received, through a finger of a plurality of fingers in a receiver, at a time that is later than a reference time after a reference signal is received by a reference finger of the plurality of fingers. The reference signal may be included in an on-time group corresponding to a cell. The first signal may be included in a late group corresponding to a virtual cell. The first signal and the reference signal may be compared to one another. Based on the comparing, it may be determined whether to wait for additional signals in the late group or process the signals in the on-time group.

Abstract: Spur cancellation systems and related methods are disclosed for radio frequency (RF) receivers and other implementations. Disclosed embodiments effectively remove spurs caused by digital clock signals or other spur sources by determining which spurs will fall within a channel selected to be tuned, utilizing a spur cancellation module to generate a cancellation signal, and subtracting this cancellation signal from the digital information. The cancellation signal can be initially generated with a known frequency and estimated values for unknown spur parameters, such as amplitude and phase. Digital feedback signals are then used to adjust the spur parameters. If the spur frequency is not known precisely, digital feedback signals can also be used to adjust the frequency of the cancellation signal. Where multiple receive paths are provided within a multi-receiver system, multiple spur cancellation modules can be used to remove spurs generated by digital clocks within each of the receive paths.

Abstract: A receiver circuit provides improved noise estimation processing by at least partially removing receiver frequency error bias. An initial noise estimate is compensated using an error term based on the observed receiver frequency error, and the resulting compensated noise estimate can be used to improve other signal processing in the receiver. For example, the receiver may use compensated noise estimates to generate signal quality estimates, e.g., Signal-to-Interference (SIR) estimates, having improved accuracy. Additionally, or alternatively, the receiver may use the compensated noise estimates to generate RAKE combining weights having improved noise suppression characteristics. In an exemplary embodiment, the initial noise estimate is a noise correlation matrix generated from a received reference signal, e.g., pilot symbols, and the error term is an error matrix directly generated using he observed receiver frequency error and channel estimates taken from the reference signal.

Abstract: A digital circuit includes at least one input node, a biasing circuit, and a digital baseband circuit. The input node receives a digital signal including samples at a plurality of sample instances, the samples including a positive sample and a negative sample and represented by first plurality of bits. The biasing circuit generates a biased digital signal by adding a bias value to the digital signal so as to change the positive sample and the negative sample to first sample and second sample respectively and represented by second plurality of bits. The digital baseband circuit is configured to receive and process the biased digital signal such that reduced current consumption is realized based on a number of bit toggles in the second plurality of bits being less than a number of bit toggles in the first plurality of bits.

Abstract: Method and apparatuses are disclosed to substantially compensate for various unwanted interferences and/or distortions within a communications receiver. Each of these apparatuses and methods estimate the various unwanted interferences and/or distortions within the communications receiver. Each of these apparatuses and methods remove the estimates of the various unwanted interferences and/or distortions within the communications receiver from one or more communications signals within the communications receiver to substantially compensate for the various unwanted interferences and/or distortions.

Abstract: In one embodiment, a receiver may receive a signal from a transmitter. The receiver may include a first sampler that may sample the signal when the value of the signal is zero. The receiver may further include a second sampler that may sample the signal halfway between a time when the first sampler samples the signal and the next time when the first sampler samples the signal to produce a set of sampled values. The receiver may be further operable to determine that a sampled value in the set of sampled values is a logic 1 if the sampled value is greater than the value of a reference voltage and that the sampled value is a logic 0 if the sampled value is less than the value of the reference voltage.

Abstract: A receiver front end circuit includes a low-noise amplifier including: a first receiver path having: a first low-noise transconductor to amplify a received signal and output the amplified received signal; and a first mixer to down-convert the amplified received signal. A second receiver path includes: an auxiliary receiver having: a second transconductor to output an amplified received signal; a baseband amplifier having an input port and an output port; a first resistance coupling the input port to the output port of the baseband amplifier and to convert the amplified received signal from current to voltage and set a voltage gain of the second receiver path; and a second resistance coupled from the output port of the baseband amplifier to the first mixer output. In some examples, frequency-upconversion feedback path includes a third mixer to frequency up-convert the amplified received signal at an output of the second receiver path.

Abstract: Radio frequency (RF) receivers having whitened digital clocks and related methods are disclosed. Disclosed embodiments generate whitened clocks having random variations that are used to operate digital processing blocks so that interference created by the whitened clocks is seen as white noise within the received RF signal spectrum. RF input signals are received by RF front-ends (RFFEs) that output analog signals associated with channels within the RF input signals. These analog signals are converted to digital information and processed by digital receive path circuitry that outputs digital data associated with the channel. The digital receive path circuitry includes a whitened clock generator that generates a whitened clock having random variations and which a digital processing block that operates based upon the whitened clock. Further, the RFFE and the digital receive path circuitry are located within a single integrated circuit.

Abstract: The present invention reduces the degradation in performance of one or more radio signals that are co-transmitted with a first radio signal from the same transmitting antenna in the same frequency channel and received by the same antenna due to multipath or other shared interference, where the one or more radio signals can be separated from the first radio signal. All received signals are coupled to the same adaptive array or adaptive filter to reduce multipath or other shared interference of the first radio signal, which reduces multipath and other shared interference in the other radio signals before they are separated and processed by their respective receivers, or the individual radio signals are separated before the first signal enters the adaptive array and coupled to a slave weighting network slaved to the weights of the adaptive array of the first signal to reduce interference in all the signals.

Abstract: Techniques are provided that utilize information on the characteristics of the transmitted signal to improve the accuracy of the I/Q imbalance estimation and correction. These techniques can be used to achieve improved image rejection performance over existing solutions, through the use of signal conditioning, windowing and the use of statistical information on the received signal. A number of techniques aimed at improving the accuracy of the I/Q imbalance estimation/correction are presented, including different modes of I/Q imbalance estimation and I/Q imbalance correction in the presence of a complex IF filter in the transceiver. The processing is performed mostly in the DBB in order to be area/power efficient.

Abstract: A calibration system may be provided for calibrating wireless communications circuitry in an electronic device during manufacturing. The calibration system may include data acquisition equipment and calibration computing equipment for receiving and processing test and calibration signals from wireless communications circuitry to be calibrated. During testing and calibration operations, a device may be provided with initial pre-distortion calibration values. The initial pre-distortion calibration values may be generated at least in part based on calibration operations performed for other wireless electronic devices. The device may generate a test signal using the initial pre-distortion calibration values. The calibration system may determine whether the test signal is within an acceptable range of a known reference signal.

Abstract: A transmit (TX) signal path circuit in a multiple-input, multiple-output (MIMO) transceiver responsive to a digital front end (DFE) for generating receive (RX) path phase alignment signals is disclosed. A digital up-conversion block uses a first numerically-controlled oscillator (NCO) for generating digital intermediate frequency (IF) signals for ordinary TX signal generation, and a different, second NCO for generating digital IF signals for RX phase alignment signal generation. An RF up-conversion block uses a TX local oscillator (LO) for generating analog RF signals for ordinary TX signal generation, and a different feedback (FB) LO for generating analog RF signals for RX phase alignment signal generation. Thus, phase alignment of the circuitry used for ordinary TX signal generation is left undisturbed by RX phase alignment signal generation.

Abstract: A method and system for compensating for frequency dependent phase and amplitude imbalances is provided. A plurality of frequency sub-bands is extracted from a received wideband signal. Each of the plurality of frequency sub-bands is compensated to produce an associated plurality of compensated frequency sub-bands. The compensated sub-bands are summed in order to produce a compensated signal.

Abstract: A stream of information is communicated by means of transmission distributed over a plurality of transmission antennas and reception distributed over a plurality of reception antennas. In the method the stream is encoded according to an error correcting code, into a series of multi-bit symbols. A sequence of the multi-bit symbols is interleaved, by which symbols are assigned to time slots, so that the multiple bits of the symbols remain together in the same time slot. The interleaved multi-bit symbols are transmitted, with each symbol distributed over the transmission antennas in a respective time slot. Signals received at the reception antennas in each respective time slot are received and demodulated, to produce demodulation results each for a respective time slot. A time-slot sequence of the demodulation results is deinterleaved. Decoded symbol values are selected under a constraint that a series of the selected symbols belongs to the error correcting code.

Abstract: A method of canceling sinusoidal interference from a received signal includes identifying a block of signal-free data containing sinusoidal interference. A model of the significant interference in the selected data block is constructed, scaled to subsequent data blocks and used to remove sinusoidal interference signals from the overall received signal.

Abstract: Distortion caused by spurious components in a determined channel impulse response (CIR) is reduced. In an OFDM (orthogonal frequency-division multiplexing) system pilot signals are applied to different subcarriers of different symbols in accordance with a pilot transmission scheme. Channel estimates are determined by time-interpolation for some of the data slots of the received signal which do not already include a pilot signal. For each of a sequence of symbols, a respective Inverse Fast Fourier Transform is performed on the pilot signals and interpolated channel estimates in the data slots of that symbol, thereby determining a sequence of estimated CIRs for the sequence of symbols. Spurious channel components will vary across the sequence of estimated CIRs, whereas the true channel peaks will tend not to significantly vary across the sequence of estimated CIRs. Therefore the sequence of estimated CIRs can be filtered (e.g.

Abstract: A receiver receives radio frequency (RF) energy including a desired signal and interference including high-level narrowband interference and low-level wideband interference. A first stage canceler cancels the high-level narrowband interference from the received RF energy based on a first correction signal representative of the interference, to produce a first canceler output signal. A second stage canceler frequency down-converts to baseband, and filters the high-level narrowband interference from, a sample of the first correction signal, to produce a second correction signal including the low-level wideband interference frequency down-converted to baseband. A digital canceler digitally cancels the low-level wideband interference from the first canceler output signal based on the second correction signal, to recover the desired signal.

Abstract: An object of the present invention is to provide a receiving apparatus and a receiving method capable of preventing phase rotation of a signal after FFT from occurring on a frequency domain. Further, the receiving apparatus according to the present invention is provided with: a window control unit configured to control a position of an FFT window in which FFT is performed to the time domain signal, and output FFT data corresponding to the FFT window; a signal delaying unit configured to generate, from the time domain signal, a plurality of delay signals with different delay amounts; and a signal switching unit having a switch for outputting by switching between two of the time domain signal and the plurality of delay signals based on a predetermined switch timing, the signal switching unit being configured to output the FFT data including the output signal of the switch.

Abstract: A method and apparatus for frequency offset estimation exploits the differences in reference symbol timing for different channels to resolve ambiguities in the frequency offset estimation. Based on the initial frequency offset estimates, a hypothesis table is constructed providing hypothesized frequency offsets for each channel for a plurality of possible offset regions. An error metric for each offset region is calculated based on the difference of the hypothesized frequency offsets. The set of hypothesized frequency offsets that minimize the error metric is selected as the final frequency offset estimates.

Abstract: A radio signal transmission technique includes selecting a sample rate from a plurality of predefined sample rates so that the radio signal is contained entirely within a Nyquist zone corresponding to the sample rate. A digitized signal is converted to an analog signal, spectrally enhanced, and passed through a selected one of a plurality of selectable bandpass filters to form the radio signal.

Abstract: Embodiments of an apparatus for improving a gain imbalance between an in-phase and quadrature component recovered by a receiver are provided. The apparatus includes a first transition counter configured to count a number of bit transitions in a first sequence of one-bit values provided by a first sigma-delta modulator based on the in-phase component, and a second transition counter configured to count a number of bit transitions in a second sequence of one-bit values provided by a second sigma-delta modulator based on the quadrature component. The apparatus further includes a gain monitor configured to: (1) determine a first and second power level, proportional to a power of the in-phase and quadrature components respectively, using the number of bit transitions in the first and second sequences, and (2) adjust a gain of one of the in-phase and quadrature components based on a ratio between the first and second power levels.

Abstract: Systems and methods are provided for whitening noise of a received signal vector in a multiple-input multiple-output (MIMO) transmission or storage system. The whitening filter may be designed to whiten an interference component of the received signal vector, where the interference component is derived from modeling transmitter and receiver imperfections as a first coupling between MIMO transmitter outputs and a second coupling between MIMO receiver. The whitening filter may be computed based on the covariance matrix of the interference component.

Abstract: A method for performing joint detection includes adjusting a ranking order of codes in a matched filtering result, and a ranking order of column vectors in a system submatrix according to the power. The joint detection is performed using an adjusted matched filtering result and an adjusted system submatrix, and acquires demodulated signals corresponding to the codes. The codes that have high power will be demodulated first. This ensures accuracy of demodulation, inhibits erroneous propagation effect, and improves accuracy of the joint detection.

Abstract: A communication system includes a first communication apparatus and a second communication apparatus. The first communication apparatus generates and transmits communication data in accordance with a predetermined protocol. The second communication apparatus includes a power circuit section having a switching regulator, and is configured to receive the communication data transmitted from the first communication apparatus. The predetermined protocol includes a protocol defining that at least one portion of a bit sequence constituting the communication data should be associated with an operation of the switching regulator. The second communication apparatus causes the switching regulator to operate in a time period in which the at least one portion of the communication data is received, in a state where the communication data is received.

Abstract: Described embodiments recover timing and data information from a signal received via a communication channel. An analog-to-digital converter (ADC) operating at a baud rate of the communication channel generates an actual ADC value corresponding to each bit sample of the received signal. A fast symbol estimation module estimates, based on the actual ADC value, a bit value corresponding to each bit sample. The fast symbol estimation module operates at a digital clock rate. The estimated bit values are provided to a timing recovery module. An ADC reconstruction module, based on a first number of pre-cursor estimated bit values, an estimated cursor bit value, and a second number of post-cursor estimated bit values, generates a reconstructed ADC value corresponding to each bit sample. Based on the reconstructed ADC values, the estimated bit values, and the actual ADC values, a corrected bit value is generated for each bit sample.

Abstract: Disclosed are a broadcast signal transmitter, a broadcast signal receiver, and a method for transceiving a broadcast signal in the broadcast signal transmitter/receiver. A method for transmitting a broadcast signal comprises the following steps: signaling in-band signaling information to at least one of a service component physical layer pipe (PLP) including at least one service component of a broadcast service, a first information PLP including first service information applied to one broadcast service and a second information PLP including second service information applied commonly to a variety of broadcast services; performing the FEC encoding on data included in each PLP; performing time-interleaving on the FEC encoded data; generating a transmission frame including the time-interleaved data; and modulating the transmission frame and transmitting a broadcast signal including the modulated transmission frame.

Abstract: A device and a method within a communications system where at least some part of the transmission is executed by means of radio waves, and where symbols are transmitted by means of Orthogonal Frequency Divisional Multiplexing, so called OFDM-technology, between a transmitting unit and a receiving unit, at which the symbol transmission is executed over a transmission channel in blocks of binary digits with a guard interval GI between said blocks, where transmitting unit is equipped with means to control the length of the guard interval (GI) with regard to the physical conditions for/of the transmission channel, so that the guard interval can be reduced without the disturbance susceptibility being increased, but instead increasing the capacity/throughput of the transmission channel by the time that is set free/made available being used to transmit information. One embodiment of the invention includes a guard interval adjustment unit connected to other OFDM-equipment in transmitting and/or receiving unit.

Abstract: A station in a wireless communication system includes a processor circuitry configured to form at least a first plurality of data streams and a second plurality of data streams, and a digital precoder configured to receive the first plurality of data streams and the second plurality of data streams. The wireless station can further include a plurality of radio frequency (RF) beamforming chains connected to the digital precoder and configured to form at least one RF envelope, wherein the digital precoder is configured to steer a plurality of digital beams within the at least one RF beam envelope, the digital beams forming a plurality of spatially distinct paths for the first plurality of data streams and a plurality of spatially distinct paths for the second plurality of data streams, and a plurality of antennas operably connected to the RF beamforming chains.

Abstract: The present disclosure provides systems and methods for noise tolerant signal processing in a pilot assisted data receiver, including: given received pilots with common pilot components and individual pilot components, computing coefficients associated with the individual pilot components of the received pilots; and applying the computed coefficients to the received pilots to obtain conditioned pilots. The individual pilot components result from relatively slow changes of the received pilots relative to the common pilot components. The common pilot components result from relatively fast changes of the received pilots relative to the individual pilot components.

Abstract: An apparatus and a method for Low-density parity-check (LDPC) decoding are provided. The apparatus for LDPC decoding comprises a post effective noise variance estimation unit for estimating a post effective noise variance based on a preamble in a received signal, an LLR calculation unit for calculating an LLR based on the estimated post effective noise variance, and a decoding unit for performing LDPC decoding based on the calculated LLR. The post effective noise variance estimation unit comprises a channel frequency response estimation unit for estimating a channel frequency response based on the preamble in the received signal, a noise variance estimation unit for estimating a noise variance based on the preamble in the received signal, and a post effective noise variance calculation unit for calculating the post effective noise variance based on the channel frequency response and the noise variance.

Abstract: This invention is related to a low-complexity MIMO detector in a wireless communication system with near optimal performance. An initial symbol estimation is performed for a received symbol vector. The soft information of the received symbol vector can be more accurately calculated using every candidate symbol vector of a combined set of candidate symbol vectors, wherein the combined set is generated based on the initial estimation. By combining aspects of both the linear detection and the ML detection, the complexity of the proposed detector becomes orders of magnitude lower than that of a ML detector, but the performance is very close to that of an ML detector.

Abstract: Logic may comprise a single phase tracking implementation for all bandwidths of operation and the logic may adaptively change pre-defined and stored track parameters if the receiving packet is 1 MHz bandwidth. Logic may detect a packet and long training fields before performing a 1 MHz classification. Logic may auto-detect 1 MHz bandwidth transmissions by a property of the long training field sequences. Logic may auto-detect 1 MHz bandwidth transmissions by detecting a Binary Phase Shift Keying (BPSK) modulated first signal field symbol rather than the Quadrature Binary Phase Shift Keying (QBPSK) associated with the 2 MHz or greater bandwidth transmissions. Logic may perform an algorithm to determine an estimated phase correction value for a given orthogonal frequency division multiplexing symbol and several embodiments integrate this value with an intercept multiplier that may be 0.2 for 1 MHz transmissions and, e.g., 0.5 for 2 MHz or greater bandwidth communication.

Abstract: A method for canceling adjacent channel interference includes: receiving signal of a first channel, where an interference signal of a second channel remains in the signal of the first channel, and the second channel and the first channel are adjacent channels; receiving a cancellation signal provided by the second channel for canceling the interference signal; filtering the received cancellation signal; adjusting a frequency of the filtered cancellation signal; multiplying the cancellation signal with the adjusted frequency by a gain factor to obtain a signal to be cancelled; and subtracting the signal to be cancelled from the signal of the first channel, and canceling the interference signal to obtain a signal to be decoded. According to the technical solutions provided in the embodiments of the present invention, interference signals of adjacent channels are cancelled, and the signal to noise ratio is improved.

Abstract: A system and methods for estimating a noise power level in an uplink signal for a virtual MIMO system is disclosed. The system comprises a demodulation reference signal (DMRS) module configured to obtain a DMRS receive symbol from the uplink signal and determine a DMRS sequence for a first UE in the virtual MIMO system. An autocorrelation module is configured to calculate an average autocorrelation value for the subcarriers in the uplink signal. A cross-correlation module is configured to calculate first and second cross-correlation values of the uplink signal RZ(l) for values of l selected such that the sum of the received power from the first UE and the second UE can be accurately estimated. A noise power level module is configured to determine the noise power level for the uplink signal using the average autocorrelation value and the first and second cross correlation values.

Abstract: An enhanced VSB receiver includes a tuner which tunes an RF signal and converts it into an IF signal, an IF mixer which converts the IF signal into a baseband signal, and a demodulator which demodulates the baseband signal into a VSB signal. The enhanced VSB receiver further includes a map recovery unit which recovers VSB map information of the VSB signal, an enhanced equalizer for compensating channel distortion of the VSB signal and outputting an equalized symbol, and an enhanced Viterbi decoder for estimating whether polarity inversion occurred during a symbol period of the equalized symbol and Viterbi-decoding the equalized symbol based on the polarity estimation.