摘要:
All digital reference frequency locking. An all digital approach is provided for operation within one or more CMs within a cable modem communication system to lock the upstream of the one or more CMs to the downstream symbol clock provided from a CMTS. The locking of the CM's upstream may be performed using one of at least three different functions: (1) Locking the upstream symbol clock phase to the downstream symbol clock phase, (2) Locking the downstream symbol clock phase to the headend reference clock phase (typically 10.24 MHz or integer multiple thereof), and (3) Locking the upstream carrier frequency to the downstream symbol clock frequency. The all-digital techniques for supporting all digital reference frequency locking functionality provide high performance to support S-CDMA and other synchronous modulation techniques.
摘要:
A method of managing traffic in a communications channel includes the steps of receiving a subscriber ID corresponding to a subscriber, performing a spectral analysis on a signal received from the subscriber within a time interval identified by the subscriber ID, and adjusting transmission characteristics of the subscriber based on the spectral analysis.
摘要:
A system for detecting collisions in a shared communications medium, such as a TDMA medium, includes a receive path adapted to generate a first intermediate signal, a second intermediate signal, and a data symbol sequence from an input signal. A preamble detection module generates a correlation metric from the first intermediate signal. A power measurement module generates a power indication signal from the second intermediate signal. A noise measurement module generates a noise indication signal from the second intermediate signal and the data symbol sequence. A processing module is adapted to characterize the input signal as a collision for certain values of correlation metric, power indication signal, and noise indication signal.
摘要:
A method of parameter estimation in a shared channel communications system includes the steps of receiving a preamble including a first sequence corresponding to a sequence having zero autocorrelation, a second sequence having zero autocorrelation, and a third sequence having zero autocorrelation, performing a coarse carrier frequency estimate based on the first sequence, and performing a fine carrier frequency estimate based on the second and third sequences.
摘要:
A method of parameter estimation in a shared channel communications system includes the steps of receiving a preamble including a first sequence corresponding to a sequence having zero autocorrelation, a second sequence having zero autocorrelation, and a third sequence having zero autocorrelation, performing a coarse carrier frequency estimate based on the first sequence, and performing a fine carrier frequency estimate based on the second and third sequences.
摘要:
A method of managing traffic in a communications channel includes the steps of receiving a subscriber ID corresponding to a subscriber, performing a spectral analysis on a signal received from the subscriber within a time interval identified by the subscriber ID, and adjusting transmission characteristics of the subscriber based on the spectral analysis.
摘要:
A method of parameter estimation in a shared channel communications system includes the steps of receiving a preamble including a first sequence corresponding to a sequence having zero autocorrelation, a second sequence having zero autocorrelation, and a third sequence having zero autocorrelation, performing a coarse carrier frequency estimate based on the first sequence, and performing a fine carrier frequency estimate based on the second and third sequences.
摘要:
A method of managing traffic in a communications channel includes the steps of receiving a subscriber ID corresponding to a subscriber, performing a spectral analysis on a signal received from the subscriber within a time interval identified by the subscriber ID, and adjusting transmission characteristics of the subscriber based on the spectral analysis.
摘要:
A system for detecting collisions in a shared communications medium, such as a TDMA medium, includes a receive path adapted to generate a first intermediate signal, a second intermediate signal, and a data symbol sequence from an input signal. A preamble detection module generates a correlation metric from the first intermediate signal. A power measurement module generates a power indication signal from the second intermediate signal. A noise measurement module generates a noise indication signal from the second intermediate signal and the data symbol sequence. A processing module is adapted to characterize the input signal as a collision for certain values of correlation metric, power indication signal, and noise indication signal.
摘要:
A receiver includes a filter stage that receives, filters, and equalizes a received signal, and a decisional feedback loop coupled to the filter stage that receives and processes a signal output from the filter stage using remodulation. The decisional feedback loop includes a converter that generates a baseband signal, a detector that generates a decision signal, a restorative signal generator that generates a restorative signal using remodulation, and a carrier loop that generates a frequency correction signal and provides a frequency-offset estimate. The restorative signal and the frequency correction signal are provided to the converter to compensate for inter-symbol interference. The presented “remodulation” technique decouples interaction between the carrier loop, the pre-filters, and the equalizer of the restorative signal generator, providing an architecture that is more stable and significantly faster than conventional architectures.