Abstract: An inter-carrier interference (ICI) mitigation circuit associated with an orthogonal frequency division multiplexing (OFDM) receiver is disclosed. The ICI mitigation circuit comprises an ICI cancellation circuit configured to receive an OFDM symbol associated with an OFDM signal and determine an ICI associated with one or more OFDM subcarriers within the OFDM symbol. The ICI cancellation circuit is further configured to cancel the ICI from the one or more OFDM subcarriers associated with the OFDM symbol, in order to generate a desired OFDM symbol. In some embodiments, the ICI is determined and cancelled at the ICI cancellation circuit, in accordance with a predetermined ICI mitigation algorithm.

Abstract: A cable modem system for discovering interference groups (IGs) includes an infrastructure and a cable modem termination system (CMTS). The infrastructure is for transferring data. The CMTS is configured to initiate generation of test signals by a set of cable modems (CMs), obtain a set of test measurements for the set of CMs, discover interference groups (IGs) of the set of CMs based on the obtained set of test measurements and assign a plurality of upstream and downstream channels for the set of CMs that use orthogonal frequency division multiplexing (OFDM) based on the discovered IGs.

Abstract: The disclosure generally relates to a method and apparatus for frequency interleaving. Specifically, an embodiment of the disclosure relates to a communication system having one or more antennas, a radio, a memory circuit, and a processor circuit. The antennas can be used to communicate signals or to comply with different transmission protocols. The radio can be configured to send and receive radio signals. The memory can communicate with the processor circuit and contain instructions for the processor circuit to write data carriers along a plurality of rows and columns of a 2-D store in bit-reversed order and read the columns of 2-D store.

Abstract: The disclosure generally relates to a method and apparatus for frequency interleaving. Specifically, an embodiment of the disclosure relates to a communication system having one or more antennas, a radio, a memory circuit, and a processor circuit. The antennas can be used to communicate signals or to comply with different transmission protocols. The radio can be configured to send and receive radio signals. The memory can communicate with the processor circuit and contain instructions for the processor circuit to write data carriers along a plurality of rows and columns of a 2-D store in bit-reversed order and read the columns of 2-D store.

Abstract: Methods and architectures for blind detection of physical layer control (PLC) signaling for transmitters and receivers having respective misaligned inverse fast Fourier transforms (IFFTs) and (FFTs) includes opening a frequency tracking offset calibration circuit, estimating or calculating a phase discontinuity due to FFT misalignment, closing the frequency tracking offset calibration circuit and applying a frequency correction that includes a frequency offset less the calculated or estimated phase discontinuity.

Abstract: 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.

Abstract: 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.

Abstract: One embodiment provides an apparatus. The apparatus includes an optimization module configured to determine a guard interval remainder based, at least in part on a comparison of an allowable microreflection interference level and an actual microreflection interference level; and a windowing module configured to window an OFDM (orthogonal frequency division multiplexed) symbol utilizing the guard interval remainder. The apparatus may further include a channel estimator module configured to determine a predicted channel frequency response based, at least in part, on a probing symbol; and a pre-equalizer module configured to pre-equalize the OFDM symbol based, at least in part, on the predicted channel frequency response.

Abstract: 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.

Abstract: 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.

Abstract: One embodiment provides an apparatus. The apparatus includes an optimization module configured to determine a guard interval remainder based, at least in part on a comparison of an allowable microreflection interference level and an actual microreflection interference level; and a windowing module configured to window an OFDM (orthogonal frequency division multiplexed) symbol utilizing the guard interval remainder. The apparatus may further include a channel estimator module configured to determine a predicted channel frequency response based, at least in part, on a probing symbol; and a pre-equalizer module configured to pre-equalize the OFDM symbol based, at least in part, on the predicted channel frequency response.

Abstract: 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.

Abstract: One embodiment provides an apparatus. The apparatus includes an optimization module configured to determine a guard interval remainder based, at least in part on a comparison of an allowable microreflection interference level and an actual microreflection interference level; and a windowing module configured to window an OFDM (orthogonal frequency division multiplexed) symbol utilizing the guard interval remainder. The apparatus may further include a channel estimator module configured to determine a predicted channel frequency response based, at least in part, on a probing symbol; and a pre-equalizer module configured to pre-equalize the OFDM symbol based, at least in part, on the predicted channel frequency response.

Abstract: 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.

Abstract: 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.

Abstract: One embodiment provides an apparatus. The apparatus includes an optimization module configured to determine a guard interval remainder based, at least in part on a comparison of an allowable microreflection interference level and an actual microreflection interference level; and a windowing module configured to window an OFDM (orthogonal frequency division multiplexed) symbol utilizing the guard interval remainder. The apparatus may further include a channel estimator module configured to determine a predicted channel frequency response based, at least in part, on a probing symbol; and a pre-equalizer module configured to pre-equalize the OFDM symbol based, at least in part, on the predicted channel frequency response.

Abstract: 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

Abstract: The disclosure generally relates to a method and apparatus for frequency interleaving. Specifically, an embodiment of the disclosure relates to a communication system having one or more antennas, a radio, a memory circuit, and a processor circuit. The antennas can be used to communicate signals or to comply with different transmission protocols. The radio can be configured to send and receive radio signals. The memory can communicate with the processor circuit and contain instructions for the processor circuit to write data carriers along a plurality of rows and columns of a 2-D store in bit-reversed order and read the columns of 2-D store.

Abstract: 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.

Abstract: A system according to one embodiment includes a demodulator configured to receive an OFDM modulated signal over a channel, the signal including a sequence of symbols, each of the symbols including one or more pilot carriers and one or more data carriers; a time filtering and interpolation circuit coupled to the demodulator, the time filtering and interpolation circuit configured to estimate the frequency response of the channel based on time filtering and interpolation of the pilot carriers; a phase slope correction circuit configured to apply each of a plurality of phase slope corrections to the frequency response and to the data carriers; a frequency filtering and interpolation circuit configured to calculate frequency response estimates of the channel at data carrier frequencies based on frequency filtering and interpolation of the phase slope corrected frequency response; an equalization circuit configured to equalize the phase slope corrected data carriers based on the calculated frequency response estim