Abstract: A system and method for interference cancellation is provided to cancel/greatly reduce the interference of a wireless network. The interferers are separated from a desired signal using independent component analysis by hypothesizing the transmitting sequence. An optional whitening filter is used after the signal separation to improve the signal conditioning. The separated signal is processed by a second pass channel estimation to improve the signal channel estimation and is fed to a Maximum Likelihood Sequence Estimation (MLSE) algorithm, such as a Viterbi algorithm, for signal detection.

Abstract: A Wireless Regional Area Network (WRAN) receiver comprises a transceiver for communicating with a wireless network over one of a number of channels, and an Advanced Television Systems Committee (ATSC) signal detector for use in forming a supported channel list comprising those ones of the number of channels upon which an ATSC signal was not detected. The ATSC signal detector comprises a matched filter that matches to at least a modulated version of an ATSC field sync signal for detecting the presence of an incumbent ATSC broadcast signal.

Abstract: A unique digital compression technology for increasing the information carrying capacity of a bandwidth limited communications path highway by using a combined coding and modulation technique. The inventive technology allows multiple independent modulated data streams to simultaneously and instantaneously share the same bandwidth without cross-channel interference. A matched filter is used to substantially reduce the error rate and utilizes a unique training method based on performing a spectral response test. An algorithm calculates the effect of the unique characteristics of the communications highway on the transmitted signal and generates an ideal signal stored in the matched filter for comparison with received signals.

Abstract: Distortion and aliasing reduction for digital to analog conversion. Synthesis of one or more distortion terms made based on a digital signal (e.g., one or more digital codewords) is performed in accordance with digital to analog conversion. The one or more distortion terms may correspond to aliased higher-order harmonics, distortion, nonlinearities, clipping, etc. Such distortion terms may be known a priori, such as based upon particular characteristics of a given device, operational history, etc. Alternatively, such distortion terms may be determined based upon operation of a device and/or based upon an analog signal generated from the analog to conversion process. For example, frequency selective measurements made based on an analog signal generated from the digital to analog conversion may be used for determination of and/or adaptation of the one or more distortion terms. One or more DACs may be employed within various architectures operative to perform digital to analog conversion.

Abstract: Distortion and aliasing reduction for digital to analog conversion. Synthesis of one or more distortion terms made based on a digital signal (e.g., one or more digital codewords) is performed in accordance with digital to analog conversion. The one or more distortion terms may correspond to aliased higher-order harmonics, distortion, nonlinearities, clipping, etc. Such distortion terms may be known a priori, such as based upon particular characteristics of a given device, operational history, etc. Alternatively, such distortion terms may be determined based upon operation of a device and/or based upon an analog signal generated from the analog to conversion process. For example, frequency selective measurements made based on an analog signal generated from the digital to analog conversion may be used for determination of and/or adaptation of the one or more distortion terms. One or more DACs may be employed within various architectures operative to perform digital to analog conversion.

Abstract: An apparatus and method for assigning subchannels of a transmitter in a communication system. The method includes dividing an entire frequency band into m subcarrier groups; mapping each of the m subcarrier groups to a subcarrier group index, wherein a subchannel includes n subcarriers selected from each of the m subcarrier groups corresponding to a subcarrier group index sequence; determining that a first data is needed to transmit in a first timing point; and assigning a first subchannel in the first timing point using a first subcarrier group index sequence. The first subcarrier group index sequence is different from a second subcarrier group index sequence used for assigning a second subchannel in a second timing point.

Abstract: Methods, apparatus, and articles of manufacture are described for improving distortion performance and for direct current offset cancellation in receivers. In one example, a method of improving distortion in a receiver includes determining a direct current (DC) amplitude of an offset signal, generating the offset signal, and providing the offset signal to an output of a mixer to improve the distortion performance of the mixer.

Abstract: A method and apparatus for matching compressed video data under a wireless fading environment are disclosed. The apparatus includes an encoder for encoding and outputting the video data as a compressed bit stream, a channel error measurement unit for measuring Signal-to-Noise Ratio (SNR) or Carrier-to-Noise Ratio (CNR) of a wireless channel, and an encoder optimization module for determining if the current fading is slow fading or fast fading. A control signal is output to reduce a frame transmission ratio or to change the quality of the vide data if it is determined that the current fading is slow fading. Another control signal is output to adjust the size of a data output buffer of the wireless channel if it is determined that the current fading is fast fading.

Abstract: A method for reducing ringing in a signal output from a filter comprising inputting a signal into a filter; filtering a first portion of the input signal to generate a filtered portion of the output signal; analyzing the filtered portion of the output signal; detecting if ringing is present in the filtered portion of the output signal based on said analysis; and adjusting the filter characteristics to reduce ringing in a subsequent filtered portion of the output signal if it is determined that ringing is present.

Abstract: A startup protocol is provided for use in a communications system having a communications line with a master transceiver at a first end and a slave transceiver at a second end, each transceiver having a noise reduction system, a timing recovery system and at least one equalizer all converging at startup of the system. The operation of the startup protocol is partitioned into stages. The first stage includes the step of converging the equalizer and the timing recovery system of the slave while converging the noise reduction system of the master. Upon completion of the first stage the protocol enters a second stage which includes the step of converging the equalizer and the timing recovery system of the master, converging the noise reduction system of the slave, freezing the timing recovery system of the slave, and resetting the noise reduction system of the master.

Abstract: A method and apparatus for controlling phase locked loop are provided. The apparatus includes a voltage controlled oscillator configured to generate an output signal with a frequency proportional to a control voltage fed into the oscillator. The apparatus also includes an analog loop filter connected to the oscillator and configured to form the control voltage for the oscillator, and a charge pump configured to generate a current pulse into the loop filter. The apparatus includes a phase-frequency detector operationally connected to the charge pump and configured to form waveforms, based on a reference signal and a feedback signal, the feedback signal being proportional to the output signal of the oscillator. The apparatus further includes a controller configured to modulate the feedback signal on the basis of the frequency or phase error of the output signal of the voltage controlled oscillator and the reference signal.

Abstract: It is an object of the present invention to provide a multicarrier transmission system for enabling degradation of a transmission speed in an adjacent line adjacent to a communication line, to be avoided. For this purpose, a multicarrier transmission system in the present invention is a multicarrier transmission system configured so that a first communication device and a second communication device are connected via a communication line, wherein the first communication device controls a transmission output of a signal to be outputted to the above described communication line, based on a difference between a transmission distance of the above described communication line and a transmission distance of an adjacent line adjacent to the above described communication line.

Abstract: The invention relates to the processing of a signal that is compression encoded (COD) according to a predetermined encoding type applying a quantification operation (Q) and then decoded (DEC) so that the quantification noise is present in the decoded signal (S*). The signal processing of the invention comprises applying a quantification noise reduction (TBQ) to the decoded signal (S), preferably in the following manner: first obtaining information (INF) on the type of compression encoding, selecting a model for the reduction of the quantification noise adapted to said information by estimating the quantification noise (BQ) that the encoding may have generated; and applying to the decoded signal (S*) a processing for reducing the quantification noise (FIL) according to the selected model.

Abstract: An apparatus for providing improved gray mapping may include a processor. The processor may be configured to divide gray value byte data into high priority portions and low priority portions distributed as constellation points in a constellation matrix and to provide separation between each of the constellation points by assigning a unique mapping code to a plurality of the constellation points.

Abstract: A modulator for a communications system includes a spread spectrum coder and a pulse code modulator having a signal input port connectable to a signal output port of the spread spectrum coder. The modulator performs a robust and error free modulation and coding scheme by using a modified spread spectrum scheme combined with pulse code modulation. The communication system contains a low data rate, noise robust modulation and coding scheme using a very simple transmitter. This results in a very straightforward transmitter circuit, reducing size and costs of the transmitter.

Abstract: There are provided video encoders and corresponding methods for performing fast mode decision of B-frames. A video encoder for encoding video data for a B slice that is divisible into macroblocks includes an encoder (OO) for performing mode selection when encoding a current macroblock in the B slice by counting a number of neighboring macroblocks in the B slice coded in a DIRECT mode, and only checking one of the DIRECT MODE or a 16×16 mode for the current macroblock when the number of neighboring macroblocks coded in the DIRECT mode exceeds a predetermined threshold.

Abstract: A rate adaptation method comprises the steps of: updating the probability density function of the SNR of a transmitted signal according to the receiving status of the transmitted signal and the probability density function before update; and updating the transmission rate of the transmitted signal according the updated probability density function.

Abstract: An apparatus and method for estimating a carrier-to-interference-and-noise ratio (CINR) of a received signal in an orthogonal frequency division multiplexing (OFDM) system are provided. A band-pass filter attenuates a signal region of the received signal and passes a signal in a noise region. A first power calculator calculates interference and noise power of the noise-region signal received from the band-pass filter. A second power calculator calculates total received power of the received signal. A ratio calculator calculates a CINR based on the interference and noise power, and the total received power.

Abstract: Low noise phase quadrature signals are generated after receiving a clock signal and adjusting the clock signal in response to a feedback signal to generate a phase adjusted clock signal. The clock signal and the phase adjusted clock signal are exclusive-ored to generate a frequency doubled signal. An in-phase local oscillator signal and a quadrature local oscillator signal are generated from the frequency doubled signal such that the in-phase local oscillator and the quadrature local oscillator signal are out-of-phase with each other. In addition, a phase relationship between the in-phase local oscillator signal and the quadrature local oscillator signal are detected, and the feedback signal is generated based upon the phase relationship between the in-phase local oscillator signal and the quadrature local oscillator signal.

Abstract: An apparatus for providing improved gray mapping may include a processor. The processor may be configured to divide gray value byte data into high priority portions and low priority portions distributed as constellation points in a constellation matrix and to provide separation between each of the constellation points by assigning a unique mapping code to a plurality of the constellation points.

Abstract: A wide band frequency domain canceller is used in cosite mitigation interference in which a signal tapped from a transmit antenna is coupled to a Chirp Fourier Transform to covert the signal into the frequency domain. The frequency domain signal is vector multiplied with a path transform function to add the path transfer function values to the sampled signal, after which the processed frequency domain signal is converted back into the time domain by an Inverse Chirp Fourier Transform, after which it is inverted and coupled into the receive path of a cosited receiver.

Abstract: In various embodiments of the present invention, optimal or near-optimal multidirectional context sets for a particular data-and/or-signal analysis or processing task are determined by selecting a maximum context size, generating a set of leaf nodes corresponding to those maximally sized contexts that occur in the data or signal to be processed or analyzed, and then building up and concurrently pruning, level by level, a multidirectional optimal context tree constructing one of potentially many optimal or near-optimal context trees in which leaf nodes represent the context of a near-optimal or optimal context set that may contain contexts of different sizes and geometries. Pruning is carried out using a problem-domain-related weighting function applicable to nodes and subtrees within the context tree. In one described embodiment, a bi-directional context tree suitable for a signal denoising application is constructed using, as the weighting function, an estimated loss function.

Abstract: A system and method for modulating and amplifying an input signal are provided in a communication transmitter. The transmitter includes a pre-distortion lookup table containing pre-distortion lookup data. An auto-calibration module is in communication with the pre-distortion lookup table. The auto-calibration module is configured to operate during a closed-loop auto-calibration interval and to calibrate the pre-distortion lookup data to compensate for a non-linearity in the transmitter. The pre-distortion is based on the pre-distortion lookup data and is used during an open-loop operational interval.

Abstract: A technique for PAR reduction involves producing an optimized clipping pulse. The optimized clipping pulse may be designed to meet certain requirements, such as a spectral mask target or an EVM target, when applied to a signal.

Abstract: An information handling system includes a digital circuit having a first terminal connected to a first voltage reference, and a second terminal connected to a second voltage reference. The digital circuit is configured to be coupled to a radio device. The system also includes a band pass filter having a first terminal connected to the first voltage reference, and a second terminal connected to the second voltage reference. The bandpass filter is configured to produce a low impedance response, to reduce a radio frequency noise generated at a specific frequency band of the band pass filter, and to reduce a radio frequency interference produced by the digital circuit and received at the radio device.

Abstract: An encoding method includes partitioning an input stream into first sub-blocks and second sub-blocks, encoding the second sub-blocks based on a number and location of reference sub-blocks to generate third sub-blocks when at least one of the first sub-blocks corresponds to a forbidden pattern, and rearranging the first sub-blocks and the third sub-blocks to generate an output stream. The reference sub-blocks indicate the second sub-blocks that correspond to a reference pattern and the third sub-blocks includes a redundant information sub-block and non-redundant information sub-blocks. Thus, the encoding method may properly control a direct current (DC) component.

Abstract: System and method of locating an interferer and mitigating its effect for stations of a wireless local area network. Embodiments provide a protocol and mechanism to evaluate the interferer location relative to a wireless link and to take accurate actions to mitigate the interference effect for specific cases. A method includes classifying a location of an interferer relative to a wireless communication device based on a comparison with a clear-channel threshold and a noise-tolerability threshold of the device, categorizing a location of the interferer relative to a wireless link based on a combination of the interference categories for the transmitting and the receiving devices, and mitigating interference in the wireless network according to the categorization. For example, in some cases, mitigating includes adapting a noise-tolerability threshold of the transmitting device to allow transmission.

Abstract: A method for transmitting multicast data in a WiMax/WiBro relay system, including transmitting carrier-interference-noise ratios from UEs to corresponding Relays; selecting the minimum value among the carrier-interference-noise ratios; determining the modulation and coding mode according to the selected minimum value; transmitting the modulation and coding mode to BS; selecting a modulation and coding mode with a highest rate for multicast data on an access link; transmitting the final modulation and coding mode to the Relays; and transmitting data via the access link with the modulation and coding mode determined by the BS.

Abstract: One embodiment of the present invention relates to a method of monitoring impulse noise. In the method, clusters of corrupted symbols in a stream of symbols are characterized in accordance with a cluster parameter associated with the clusters. Other methods and systems are also disclosed.

Abstract: One embodiment of the present invention relates to a method of transferring data in a communication system. In the method, an initial impulse noise protection value is determined. A number of redundancy bits is added to blocks of data to form codewords as a function of the initial impulse noise protection value, where the impulse noise protection value corresponds to a number of consecutive symbols that can be corrected. The number of symbols that can be correctly transmitted is changed by changing only the number of redundancy bits added to each block of data.

Abstract: Device, system, and method of flicker noise mitigation. For example, an apparatus includes a digital adaptive filter to mitigate flicker noise from a received Orthogonal Frequency-Division Multiplexing (OFDM) signal, wherein the digital adaptive filter includes: a prediction filter to estimate a value of the flicker noise based on linear combination of past low-pass filtered signal samples; a trainer sub-circuit to modify a coefficient of the prediction filter based on a difference between: a known incoming signal filtered by the prediction filter in a training stage, and a locally-generated reference copy of the known signal; a first path including a first pair of analysis-synthesis filters; and a second, parallel, path including a second pair of analysis-synthesis filters and further including the prediction filter.

Abstract: An acquisition apparatus includes: a first phase-calculating section that calculates a first correlation value by performing correlating operation of a reception signal and a reference signal and determines whether or not the first correlation value is equal to or greater than a first threshold; a threshold calculating section that calculates a second threshold by performing averaging operation of the first correlation value and the first threshold when the first correlation value is equal to or greater than the first threshold; and a second phase-calculating section that calculates a second correlation value by performing correlating operation of the reception signal and the reference signal on a basis of a phase of the reference signal which realizes the first correlation value equal to or greater than the first threshold, and determines whether or not the second correlation value is equal to or greater than the second threshold.

Abstract: A transmitter includes a polar modulator that creates phase and amplitude signals which in turn drive a power amplifier. To compensate for AM to PM conversion of the amplitude signal into the amplified signal, a compensation signal is generated from the amplitude signal and combined with the phase signal such that when amplified, the compensation signal cancels the AM to PM conversion. The compensation signal may have an offset term, a linear term, a quadratic term, and a cubic term. A second embodiment comprises a technique by which AM to AM conversion may concurrently be addressed using a second compensation signal.

Abstract: Digital signals are transmitted on a bus at given instants selectively in a non-encoded format and an encoded format. The decision whether to transmit the signals in non-encoded format or in encoded format is taken in part, based on a comparison of the signal to be transmitted on the bus for an instant of the aforesaid given instants with the signal transmitter on the bus for the preceding instant, so as to minimize switching activity on the bus.

Abstract: A block noise detector has a spatial difference calculator that calculates differences between values of adjacent pixels. A spatial difference comparator detects edges by comparing the calculated differences. Eight counters count edges detected at different groups of positions spaced eight pixels apart in each horizontal line. The maximum count and the group of positions at which it occurs are detected at the end of each horizontal line to detect block noise and the positions of the block boundaries. The block noise detector is small in size because it only has to count edges in one line at a time, and detects edges accurately by comparing the difference at a given position separately with differences to the left and differences to the right.

Abstract: A recursive method of calculating an inverse impairments matrix is used to generate an SINR estimate, which in turn is used to generate a CQI estimate. The recursive inverse impairments matrix calculation avoids the need to perform a computationally intensive matrix inversion, allowing for faster CQI estimate generation and consuming less power.

Abstract: Systems and methods are provided for providing a hybrid signal having a reduced crest factor. A digital signal is generated that assumes one of a plurality of vector states at discrete sampling times, with each of the plurality of vector states having an associated phase. An analog signal is monitored to determine when a phase of the analog signal is aligned with the phase of a vector state assumed by the digital signal. A crest factor reduction is applied to the digital signal if the digital signal assumes a vector state having an associated phase aligned with the phase of the analog signal to provide a compressed digital signal. The compressed digital signal and the analog signal are combined to provide the hybrid signal. The analog signal is not altered prior to being combined with the compressed digital signal.

Abstract: In estimating propagation path in an OFDM receiver in an OFDM communication system, a CIR estimation unit estimates a group of impulse responses of a propagation path, a valid-impulse discriminator selects impulse responses (CIR), which are greater than a predetermined threshold value, from the impulse-response group, and a propagation path estimation unit generates a matrix expression using a CIR estimation vector that includes the selected CIRs as elements, a matrix S, which is decided based upon number N of points of an IFFT used in OFDM modulation and number Nc of subcarriers used in actual transmission, and a propagation-path response vector, obtains the propagation-path response vector by solving this matrix expression and estimating the propagation path.

Abstract: A method of reducing ringing artifacts in image data that has been filtered with a high frequency emphasis filter. For each filtered data value, a local variance is calculated from data values at neighboring filter taps. This variance is compared to a threshold, and if the threshold is exceeded, the filtered data value is limited between local minimum and maximum values. A method of reducing noise, also using the local variance, is also described.

Abstract: Provided is a method and system for noise-driven recovery of a digital pulse stream. The method includes receiving initial parameters including the base characteristics of a pulse signal, the characteristics including the minimum pulse interval. An incoming analog signal is converted to a digital signal and sampled a predetermined number of times at intervals less than the minimum pulse interval to record a set of minimum signal values. The incoming signal is also sampled a predetermined number of times at intervals less than the minimum pulse interval to record a set of maximum signal values. At least the first greatest value from the set of maximum signal values is discarded. Each set is averaged to provide an average minimum value and an average maximum value. Based on these values at least one threshold value is then determined, and the digital pulse stream is identified based on the threshold values.

Abstract: An apparatus for producing a word of a de-interleaved sequence of bits from a sequence of bits stored in a memory is described. In one embodiment, the apparatus includes a read circuit for selecting bits of the stored sequence and forming the selected bits into a word, and a logic network arranged to produce the word of the de-interleaved sequence by concatenating sections of a plurality of words produced by the read circuit. The technique can also be used to achieve interleaving, rather than de-interleaving, of a data sequence.

Abstract: The method is based on the capability for coordination of the radio activities of two mobile radio transmitting and/or receiving devices. In the case of the method, a value of at least one characteristic variable is first of all determined, which is characteristic of the requirement for coordination of the radio activity of one or both transmitting and/or receiving devices. The coordination of the radio activity of one or both transmitting and/or receiving devices is then activated or deactivated as a function of the value.

Abstract: Various embodiments of the present invention provide systems and methods for reducing head distortion. For example, various embodiments of the present invention provide storage devices that include a storage medium, a read/write head assembly, and an adaptive distortion modification circuit. The storage medium includes information that may be sensed by the read/write head assembly that is disposed in relation to the storage medium. The adaptive distortion modification circuit receives the information sensed by the read/write head assembly and adaptively estimates and implements a distortion compensation factor in the analog domain. In some instances of the aforementioned embodiments, the read/write head assembly includes a magneto resistive head. In such instances, the distortion compensation factor is designed to compensate for non-linear distortion introduced by the magneto resistive head.

Abstract: A power line transmission apparatus is not interfered by the noise of the public power for transmitting high quality video/audio signal. The power line transmission apparatus includes an isolating unit connected between an external power line and an internal power line for isolating a high frequency noise signal carried on the external power line and transmitting a first power signal of the external power line from the external power line to the internal power line, and a power line network interface. The power line network interface includes at least one digital signal input/output interface for inputting or outputting a digital signal, converting the digital signal, and modulating the converted signal into the first power signal to form a second power signal and transmit the second power signal to the internal power line. A home network system without noise signal interference is built by utilizing several power line transmission apparatuses.

Abstract: One embodiment of the present invention relates to a method of transferring data in a communication system. In the method, an initial impulse noise protection value is determined. A number of redundancy bits is added to blocks of data to form codewords as a function of the initial impulse noise protection value, where the impulse noise protection value corresponds to a number of consecutive symbols that can be corrected. The number of symbols that can be correctly transmitted is changed by changing only the number of redundancy bits added to each block of data.

Abstract: Methods and apparatus relating to reducing exposure of radio devices to interference through adaptive selection of repetitive symbols are described. In an embodiment, a symbol may be selected for transmission to a display based on the operating frequency of a wireless device receiver. Other embodiments are also described.

Abstract: Method for generating reference signal sequence using grouping is explained. In this method, base sequences are grouped such that each group contains at least one base sequence of each length, so UE(s) can use various length sequences as a reference signal. And in this method, inter cell interference caused by using various length sequence as a reference signal sequence can be minimized by grouping sequences having the high cross correlation relation.

Abstract: Interference is cancelled from a baseband signal by synthesizing interference from estimated symbols in interfering subchannels. The estimated symbols are hard-coded, soft weighted, or zeroed, depending on the value of an estimated pre-processed signal-to-interference-and-noise ratio (SINR) in each subchannel in order to maximize a post-processed SINR. The estimated pre-processed SINR is obtained from averages of estimated symbol energies and estimated noise variances, or from related statistical procedures.

Abstract: A method and arrangement for simulating a radio channel. In the solution, a channel having paths is simulated and the delay of each path is formed separately with a low-resolution delay arrangement and a high-resolution delay arrangement in such a manner that the simulated delay of each path is the sum of the low-resolution delay and the high-resolution delay. Low-resolution delaying is performed on each path discontinuously as multiples of a predefined minimum delay. For each signal delayed by a low-resolution delay, at least one fixed, high-resolution delay is selected, which is a predefined part of the predefined minimum delay of a the low-resolution delay. Each signal delayed by a low-resolution delay is delayed by at least one selected high-resolution delay to form a path-specific total delay.

Abstract: A system and method for stabilizing a coefficient set used by a digital predistortion (DPD) engine to apply pre-distortion to a transmit signal and cancel distortion generated by a distorting element or distorting system when transmitting the transmit signal, including obtaining an initial coefficient set; rotating the initial coefficient set to maintain a phase of fundamental components (w10(t), . . . , w1Q(t)) of the initial coefficient set as a constant value; averaging in the time domain the rotated coefficient set to obtain an averaged coefficient set; applying the averaged coefficient set to the DPD engine, the initial coefficient set expressed in a first equation [27]; computing the phase of the fundamental components of the initial coefficient set with a second equation [28]; and computing the rotated coefficient set with a third equation [29].