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:
Methods and systems to vary an erasure slicer threshold based on a measure computed from prior soft and/or hard symbol decisions, identify reliable symbol estimates based on the threshold, identify unreliable symbol estimates for erasure based on the threshold, modify the identified symbol estimates, output the reliable symbol estimates and the modified symbol estimates as erasure slicer decisions, and filter the decisions in a feedback filter of a decision feedback equalizer (DFE). The erasure slicer threshold may be based on signal-to-noise ratio (SNR) or mean-squared-error (MSE). A symbol estimate may be identified for erasure when a coordinate of the corresponding soft decision is within an erasure area defined by the threshold. Symbol modification may include replacing a corresponding coordinate of the symbol estimate with a coordinate of a decision boundary associated with the erasure area.
Abstract:
A modem circuit associated with a communication system is disclosed. The modem circuit comprises a symbol tracking circuit configured to track a symbol timing associated with a downstream (DS) channel associated with the modem circuit, in accordance with a timing offset estimate. In some embodiments, the timing offset estimate comprises a unified timing offset derived based on one or more external channels associated with the modem circuit that is different from the DS channel. The symbol tracking circuit is further configured to apply a sample rate correction to a DS signal associated with the DS channel, based on the timing offset estimate comprising the unified timing offset, and apply a frequency correction to the DS signal, based on a frequency offset estimate comprising a unified frequency offset derived based on the one or more external channels.
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:
A cable modem supporting full duplex (FDX) operations. The cable modem includes a transmit circuitry configured to process a transmit signal and a receive circuitry configured to process a receive signal. The receive circuitry includes a switchable analog filter configured to filter the receive signal. The switchable analog filter is configurable for different passband frequencies. The receive circuitry also includes a digital compensation filter configured to compensate a difference in frequency response in a specific frequency band due to switching of the switchable analog filter for a different passband frequency. The cable modem also includes an adjacent channel interference (ACI) cancellation filter and an adjacent leakage interference (ALI) cancellation filter. A digital compensation filter is also used in processing the ACI cancellation signal and the ALI cancellation signal to impose or compensate the difference in frequency response due to the switchable analog filter switching.
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:
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:
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.