Patent application number | Description | Published |
20090059961 | MOBILE CHANNEL ESTIMATION ALGORITHM FOR DVB-H COFDM DEMODULATOR - A mobile channel estimation algorithm is disclosed, for use in a DVB-H coded OFDM demodulator. The mobile channel estimation algorithm estimates the mobile channel transfer function, overcoming many of the delay spread limitations without using time filtering and without having to collect many OFDM symbols. Once the channel estimate has been found for each symbol, equalization and inter-carrier-interference cancellation may be carried out relatively easily using known methods. The mobile channel estimation algorithm may be used in DVB-H as well as in other areas of OFDM. | 03-05-2009 |
20090086841 | Platform noise mitigation - In one embodiment of the invention, a Fourier transform unit convert a unsynchronized received through multiple antennas to a frequency domain. Also, a spectrum estimation unit determines a power spectrum for the unsynchronized data. A notch filter removes data within a frequency band from additional unsynchronized data based on the power spectrum. A synchronization unit synchronizes the notch filtered data and a noise estimation unit determines a noise covariance matrix between the synchronized data received from multiple antennas. In addition, an equalization unit performs channel equalization on the synchronized data based on the noise covariance matrix. | 04-02-2009 |
20090135923 | Mobile channel estimation for DVB-T COFDM demodulator - A channel estimator for use in a DVB-T system is capable of high Doppler performance without incurring restrictive delay spread limitations, in a hardware efficient manner. A first channel impulse response is generated that has ambiguity due to under-sampling in the frequency domain. A filter is then used to filter scattered pilots to generate a mask that is capable of resolving the ambiguities. In at least one approach, a finite impulse response filter is used during the mask generation process to generate a snapshot of the channel frequency response in non-real time. In another approach, an infinite impulse response filter is used during the mask generation process to generate a channel frequency response in real time. | 05-28-2009 |
20090167945 | DEVICE, SYSTEM, AND METHOD OF MITIGATING INTERFERENCE TO DIGITAL TELEVISION SIGNALS - Device, system, and method of mitigating interference to digital television signals. For example, an apparatus includes a diversity-based digital television receiver having a filter controller and at least first and second channel paths, wherein the first channel path includes a first Global System for Mobile communication (GSM) reject filter, the second channel path includes a second GSM reject filter, the second channel path is parallel to the first channel path, and the filter controller is to selectively switch an operational state of the first GSM reject filter. | 07-02-2009 |
20090268101 | Direct conversion television receiver - A direct conversion television receiver may include a phase de-rotator which substantially undoes the phase rotation of a phase rotator. The phase de-rotator takes the low pass filtered signal and substantially removes the rotation caused by the phase rotator. As a result, it is easier to estimate the phase and gain imbalance and to make a correction for the phase and gain imbalance, via a feedback loop, without the effects of phase rotation. | 10-29-2009 |
20100158141 | METHODS AND SYSTEMS TO ESTIMATE CHANNEL FREQUENCY RESPONSE IN MULTI-CARRIER SIGNALS - Methods and systems to determine channel frequency responses corresponding to multi-carrier signals, such as OFDM signals, including to filter or mask noise from channel frequency response estimates in a time domain. | 06-24-2010 |
20100166088 | METHOD AND SYSTEM FOR OFDM SYMBOL TIMING RECOVERY - A method and system for OFDM symbol timing recovery is described. A symbol timing recovery module of an OFDM receiver is configured to determine an optimum trigger point for performing a discrete Fourier transform in a manner that minimizes inter-symbol interference. | 07-01-2010 |
20100166115 | Phase error detection with conditional probabilities - Apparatuses, systems, and methods that employ conditional probabilities to calculate phase errors are disclosed. For a received signal, the embodiments may develop several phase error estimates relative to each point of a constellation, the number and location of points of the constellation depending on the modulation technique of the received signal. In addition to calculating the phase error estimates, the embodiments may also calculate weights, or probabilities, associated with each of the estimates. The embodiments may use the estimates and the weights to calculate a composite phase error estimate. The composite phase error estimate may be used to correct the received signal and eliminate or reduce the impact of the phase error. | 07-01-2010 |
20100169734 | BROADCAST RECEIVER AND METHOD FOR OPTIMIZING A SCALE FACTOR FOR A LOG-LIKELIHOOD MAPPER - Embodiments of a broadcast receiver and method for optimizing a scale factor in a log-likelihood ratio (LLR) mapper are generally described herein. In some embodiments, the broadcast receiver includes an LLR mapper to generate LLRs from demodulated data samples, a low-density parity-check (LDPC) decoder to generate decoded data from the LLRs, and an LLR optimizer to dynamically select a scale factor for the LLR mapper based on a number of iterations for convergence of the LDPC decoder. In some embodiments, the LLR optimizer iteratively revises the scale factor during receipt of broadcast signals until the number of iterations of the iterative decoder is either minimized for convergence or minimized for convergence failures. | 07-01-2010 |
20100322326 | Efficient tuning and demodulation techniques - Techniques for the reception and processing of wireless signals are disclosed. For instance, an apparatus may include a first hardware module (e.g., a mixed signal module) and a second hardware module (e.g., a digital signal module). The first hardware module may convert an analog signal corresponding to a received wireless signal into a digital signal having a first sampling rate. In turn, channel filtering may be performed on this digital signal. Following this, the filtered digital signal may be resampled from the first sampling rate to a second sampling rate. At this point, the resampled signal may be transferred across an interface from the first hardware module to the second hardware module. Upon receipt, the second hardware module may correct a sampling rate error in the second sampling rate, and demodulate the digital signal into one or more symbols. | 12-23-2010 |
20100330932 | Apparatus and methods for efficient implementation of tuners - Embodiments of systems and methods for the efficient implementation of tuners are generally described herein. Other embodiments may be described and claimed. | 12-30-2010 |
20110149171 | Efficient tuning and demodulation techniques - Techniques for the reception and processing of wireless signals are disclosed. For instance, an apparatus may include multiple receiving paths, a content stream generation module, and a distribution module. The multiple receiving paths include a first receiving path that generates a first decoded signal from an input RF signal in accordance with a first tuning setting. The content stream generation module has first and second inputs. Based on decoded signals received at the first and second inputs, the content stream generation module may generate first and second content streams, respectively. In situations where both the first and second content streams correspond to the first tuning setting, the distribution module provides the first decoded signal to both the first and second inputs of the content stream generation module. Also, a control module may remove operational power from any of the plurality of receiving paths that are currently being unused. | 06-23-2011 |
20110154148 | SPECTRAL CONTENT BASED DECODING AND FREQUENCY OFFSET ESTIMATION - Methods and systems to identify a codeword associated with samples of a signal from spectral content of the samples, and to estimate a frequency offset from the spectral contents. The samples may correspond to a physical layer header of a data frame. Modulation may be removed from the samples in accordance with each of a plurality of modulation sequences, each sequence associated with a corresponding codeword. Power levels in spectral contents of the modulation-removed samples are examined to identify a peak power level indicative of a match between a modulation sequence and the samples. The corresponding codeword is identified as being associated with the header, and transmission parameters associated with the identified codeword are used to decode a corresponding frame. An estimated frequency offset may be determined from a frequency associated with the peak power level. | 06-23-2011 |
20110158334 | PARAMETER AND SCATTERED PILOT BASED SYMBOL TIMING RECOVERY - Methods and systems to resolve the cyclic time ambiguity of a scattered pilot based channel impulse response, including to determine a channel impulse response from a combination of scattered pilots and encoded parameters, such as L1-pre signaling within P2 symbols of a terrestrial digital video broadcast (DVD) in a single frequency network (SFN), and including to re-use a corresponding window time to track the channel impulse response in the absence of encoded parameters. Methods and systems disclosed herein may be implemented with respect to channel acquisition and tracking, including adjusting a Fast Fourier Transform trigger point to reduce inter-symbol interference. | 06-30-2011 |
20120134398 | FREQUENCY AND TIMING OFFSET ESTIMATION ALGORITHM FOR DTV (DVB-T2) RECEIVERS - According to various embodiments, a method is disclosed that includes a method is disclosed that includes determining, by a receiver, a frequency offset in a signal comprising a set of orthogonal frequency division multiplexed (OFDM) symbols by determining a first difference in phase angles between a n | 05-31-2012 |
20120212675 | APPARATUS, SYSTEMS AND METHODS UTILIZING ADJACENT-CHANNEL POWER DEPENDENT AUTOMATIC GAIN CONTROL FOR DIGITAL TELEVISION DEMODULATION - An embodiment of the present invention provides a method for digital television demodulation, comprising using adjacent-channel power dependent automatic gain control (AGC) for the digital television demodulation, wherein an AGC technique takes into account a total power as well as power of adjacent channels to control gain of a gain control amplifier. | 08-23-2012 |
20130022097 | ADAPTIVE FREQUENCY-DOMAIN EQUALIZATION FOR WIRELESS RECEIVERS - According to various embodiments, devices and methods disclosed herein include performing, using a processor, a linear operation on a first plurality of channel frequency responses and a plurality of corresponding predictor coefficients to estimate a new channel frequency response. Each of the plurality of corresponding predictor coefficients may be updated based on an error value and a second plurality of channel frequency responses to obtain an updated predictor coefficient. The error value may be computed based on an estimated current channel frequency response and a predicted current channel frequency response. The new channel frequency response may be used to equalize a received modulated signal including a single-carrier modulated signal, e.g., a signal modulated using a vestigial sideband modulation scheme, or a quadrature amplitude modulation scheme. | 01-24-2013 |
20130107992 | PHASE DETECTION IN DIGITAL COMMUNICATION RECEIVERS | 05-02-2013 |
20130272357 | METHOD, APPARATUS AND SYSTEM OF TRANSFERRING DATA BETWEEN ELEMENTS OF A CABLE COMMUNICATION DEVICE - Some demonstrative embodiments include devices, systems and methods of transferring information between elements of a communication device. For example, a device may include a front-end to receive an analog downstream input including a plurality of downstream data channels, and to provide a digital serial downstream output including at least one continuous stream of constant-size downstream frames including a plurality of constant-size downstream data frames, which include downstream sample data of the plurality of downstream data channels; a serial interface including at least one serial lane to transfer the at least on stream of the digital serial downstream output; and a processor to receive the digital serial downstream over the serial interface, and to process the downstream data frames. | 10-17-2013 |
20130272460 | INTER CARRIER INTERFERENCE CANCELLATION FOR ORTHOGONAL FREQUENCY DOMAIN MULTIPLEXING RECEIVERS - Apparatus and methods are described to perform inter carrier interference (ICI) reduction or cancellation in an orthogonal frequency domain multiplexing (OFDM) receiver. A first and a second stage of ICI cancellation may be performed before inputting an estimated transmitted data carrier for forward error correction. Forward error correction may include a signal re-correction and reconstruction of the estimated transmitted data carrier prior to a further stage of ICI cancellation. | 10-17-2013 |
20130343501 | PHYSICAL LAYER CHANNEL SYNCHRONIZATION METHOD FOR HIGH BIT-RATE CABLE TRANSMISSIONS - A system and method are described to provide a next generation cable gateway/modem based on the DOCSIS standard with a scheme to synchronously combine channels in the physical layer to increase overall bit rates for coaxial cable data transmission. The systems and methods synchronize the counters associated with multiple channels, including continuity counters, at the transmitter to zero and then allow the counters on individual channels to increment individually. At the receiver, individual channel delays of individual channels will be thus recognizable based on the information provided by the counters associated with each channel. A buffer at the receiver is informed and used to individually delay one or more of the multiple channels to many up continuity counter values. In this manner, the buffer acts to essentially equalize delays in individual channels with the continuity counter representing the mechanism for specifying the individual delays for the separate channels. | 12-26-2013 |
20140029708 | DYNAMIC OPTIMIZATION OF CARRIER RECOVERY PERFORMANCE FOR COMMUNICATION SYSTEMS - Apparatuses, systems, and methods are directed to maintaining optimal carrier tracking performance in view of operating conditions that prevail. Such configurations employ a phase lock loop that configured to generate an estimated phase error value, a variance module configured to calculate a phase noise variance based on the estimated phase error value, and a loop control bandwidth module that calculates a loop bandwidth value based on a detected lower phase noise variance, generates modified loop filter values in accordance with the calculated loop bandwidth value, and updates the phase lock loop with the modified loop filter values. During subsequent iterations, the modified loop filter values are incrementally adjusted along a particular direction until the phase noise variance increases at which point the modified loop filter values are incrementally adjusted in an opposite direction to converge on an optimal loop bandwidth value. | 01-30-2014 |
20140036157 | APPARATUS, SYSTEMS AND METHODS UTILIZING ADJACENT-CHANNEL POWER DEPENDENT AUTOMATIC GAIN CONTROL FOR DIGITAL TELEVISION DEMODULATION - An embodiment of the present invention provides a method for digital television demodulation, comprising using adjacent-channel power dependent automatic gain control (AGC) for the digital television demodulation, wherein an AGC technique takes into account a total power as well as power of adjacent channels to control gain of a gain control amplifier. | 02-06-2014 |
20140064419 | APPARATUS AND METHOD FOR IMPROVING OFDM RECEIVER PERFORMANCE IN THE PRESENCE OF NARROWBAND INTERFERERS - In an Orthogonal Frequency Division Multiplex (“OFDM”) system, the problem of an interferer reducing the signal-to-noise ratio of a signal can be mitigated by generating an interferer-correction signal and subtracting it from the signal to be processed. The amplitude, frequency and phase of the interferences are determined first. The frequency is estimated by averaging the squared-magnitude of multiple FFTs of the incoming signal and then locating the spectral peaks. The phase and amplitude may be estimated from this FFT outputs or through a process of correlation in the time domain. The interferer-correction signal is generated from the estimated amplitude, frequency, and phase. The correction to be subtracted from the main signal in order to reduce the effect of the interference may be generated in the time or frequency domain. The subtraction of the correction may also be implemented in the time or frequency domains. | 03-06-2014 |
20140119420 | METHODS AND SYSTEMS TO MITIGATE IMPULSE INTERFERENCE - Methods and systems to mitigate impulse interference in an OFDM QAM signal. A per-symbol noise measure, or quality measure (QM) is computed for a symbol k as a MSE of distances between carriers in the symbol and points of corresponding QAM constellations. MSE(k) is averaged over multiple symbols to compute a background signal QM, AVG_MSE(k). If MSE(k) exceeds AVG_MSE(k) by a moderate amount, symbol k may be moderately affected by impulse interference, and per-carrier SNR estimates are downgraded for all data carriers in symbol k, prior to LLR computation. SNR downgrading may be linear or step-wise based on an extent to which MSE(k) exceeds AVG_MSE(k). If MSE(k) exceeds AVG_MSE(k) by a significant amount, symbol k may be significantly affected by impulse interference, and LLRs may be set to indicate that all data carriers are erased in symbol k. | 05-01-2014 |
20140169188 | SYSTEMS AND METHODS FOR IMPLEMENTING PEAK-TO-AVERAGE POWER RATIO REDUCTION FOR OFDMA MODULATION - A system and method are provided for implementing a peak-to-average power ratio (PAPR) reduction scheme for Orthogonal Frequency-Division Multiple Access (OFDMA) modulation. A unique PAPR reduction scheme for OFDMA modulation for systems operated according to a DOCSIS standard achieves results similar to those attributable to tone reservation schemes in a manner that does not negatively affect an amount of available data capacity, particularly in implementations with limited numbers of subcarriers. The disclosed systems and methods are particularly adaptable to next generation cable gateways and/or next generation cable modems. These next generation cable gateways and/or cable modems may find particular utility in advanced hybrid fiber/coaxial cable systems. The adaptable cable gateways/modems may include a cable gateway system-on-chip (SOC) configuration. The disclosed schemes may be applicable to OFDM modulation. For OFDM, however, the known tone reservation algorithms also may be employed. | 06-19-2014 |
20140169431 | TECHNIQUES FOR MANAGING INTERFERENCE IN MULTIPLE CHANNEL COMMUNICATIONS SYSTEM - An apparatus may include a processor circuit, and a dynamic filter adjustment component for execution on the processor. The dynamic filter adjustment component may identify in a wideband communications signal a set of one or more interferer frequencies for one or more respective interferer channels of a set of communications channels to be filtered, select a kernel filter comprising a low pass filter having a channel width corresponding to a channel of the one or more interferer channels, and generate a co-channel interference (CCI) filter to stop the one or more interferer channels by inverting the kernel filter. Other embodiments are described and claimed. | 06-19-2014 |
20140169434 | METHOD AND APPARATUS FOR PHASE NOISE MITIGATION - An approach is provided to mitigate phase noise by correcting common phase error and inter-carrier-interference in a received signal. The approach involves determining a received signal includes phase noise comprising at least a common phase error component and an inter-carrier-interference component. The approach also involves causing the common phase error to be corrected based on one or more pilot carriers. The approach further involves causing an estimate of a main signal component to be subtracted from the one or more pilot carriers. The approach additionally involves determining a sequence of estimated coefficients of a multiplicative phase noise sequence. The approach also involves causing the inter-carrier-inference to be corrected by processing the multiplicative phase noise sequence using the sequence of estimated coefficients. The approach further involves causing an equalized data signal to be output based on the corrected common phase error and the corrected inter-carrier-interference. | 06-19-2014 |
20140185657 | SYSTEMS AND METHODS FOR IMPLEMENTING SOFT-DECISION REED-SOLOMON DECODING TO IMPROVE CABLE MODEM AND CABLE GATEWAY PERFORMANCE - A system and method are provided for implementing a soft Reed-Solomon (RS) decoding scheme, technique or algorithm to improve physical layer performance in cable modems and cable gateways. At 1024-QAM, a receiver is provided in which a signal to noise ratio is reduced by at least about 1 dB relaxing design considerations and specifications for other components in the system including for the tuner. A soft-RS-symbol generation scheme is provided to enable soft-input RC decoding in a forward error correction (FEC) module connected to a QAM demodulator. The RS decoding scheme is implemented without significantly complicating hardware or processing overhead. A typical receiver hardware requirement in an FEC module to implement the disclosed scheme may be comparatively modest, e.g., on an order of approximately 50K gates. | 07-03-2014 |
20140211889 | ORTHOGONAL FREQUENCY DIVISION MULTIPLEX (OFDM) RECEIVER WITH PHASE NOISE MITIGATION AND REDUCED LATENCY - A system according to one embodiment includes a demodulator configured to receive an orthogonal frequency division multiplexed (OFDM) modulated signal comprising a current symbol and a sequence of previous symbols, each of the symbols comprising one or more pilot sub-carriers and one or more data sub-carriers; a phase angle computation circuit coupled to the demodulator, the phase angle computation circuit configured to compute a first mean, the first mean computed from the phase angle of one or more of the pilot sub-carriers of a predetermined number of the previous symbols; a predictive filter circuit coupled to the phase angle computation circuit, the predictive filter circuit configured to compute a second mean, the second mean estimating the phase angle of one or more sub-carriers of the current symbol, the estimation based on the first mean; and a phase noise cancelling circuit coupled to the predictive filter circuit, the phase noise cancelling circuit configured to correct the phase of one or more sub-carriers of the current symbol based on the second mean. | 07-31-2014 |
20140247782 | Configurable Constellation Mapping to Control Spectral Efficiency Versus Signal-to-Noise Ratio - Mixed mode constellation mapping to map a data block to a block of sub-carriers based on a configurable set of one or more constellation mapping schemes, and corresponding mixed mode least likelihood ratio (LLR) de-mapping based on the configurable set of one or more modulation schemes. The set may be configurable to include multiple modulation schemes to provide to a SEvSNR measure that is a non-weighted or weighted average of SEvSNR measures of the multiple modulation schemes. Mixed mode constellation mapping may be useful be configurable to control spectral efficiency versus SNR (SEvSNR) over a range of SNR with relatively fine SNR granularity, and may be configurable to control SEvSNR over a range of SNR at a fixed FEC code rate, which may include a highest available or highest permitted code rate. | 09-04-2014 |
20140247803 | Block-Based Time-Frequency Interleaving and De-Interleaving - Block-based interleaving to process a block of sub-carriers as a two-dimensional array defined by a frequency dimension and a time dimension. For each symbol of the array a cell is selected at each frequency index of the array in a diagonal wrap-around fashion. The array may be traversed with a modulo-based index computed as a function of an incrementing frequency index, a symbol index, and a modulus defined by a depth of the array. Cells may be selected as indicated by the frequency and time indices, and/or as indicated by a bit-reversed representation of the frequency index and/or the time index. A block interleaver may be configured to time interleave without impacting frequency, or interleave in time and frequency. Frequency interleaving may performed with the bit-reversed representation of the frequency index. | 09-04-2014 |