摘要:
A system and method are used to provide uncorrelated code hopping in a communications system. A multi-bit linear shift register receives data and clocks the data fifteen times. A word assembler receives the shifted data and outputs a fifteen bit word. A mixer mixes the fifteen bit word with an numerical value of active codes to generate a mixed signal. A divider divides the mixed signal to produce a divided signal. A truncator truncates the divided signal to its seven most significant bits to produce a pseudo random hop number. A code matrix shifter circularly shifts the active codes in a code matrix based on the pseudo random hop number to produce a circularly shifted code. A transmitter transmits the circularly shifted code matrix.
摘要:
A system and method are used to provide uncorrelated code hopping in a communications system. A shift register receives data. The shift register is clocked to shift the data. A scaler performs a scaling operation on the data with a numerical value of active codes. A truncator truncates the scaled data to its seven most significant bits to produce a pseudo random hop number. A code matrix shifter circularly shifts the active codes in a code matrix based on the pseudo random hop number to produce a circularly shifted code. A transmitter transmits the circularly shifted code.
摘要:
A distributed cable modem termination system of the present invention includes a downstream transmitter hub, an upstream receiver hub, and a head end that communicatively couples to the downstream transmitter hub and to the upstream receiver hub via a packet data network. The head end and the downstream transmitter hub are operable to synchronize a clock of the downstream transmitter hub with a clock of the head end. Further, the upstream receiver hub and the downstream transmitter hub are operable to synchronize a clock of the upstream receiver hub with the clock of the downstream transmitter hub. Clock synchronization between the upstream receiver hub and the downstream transmitter hub are performed using ranging operations supported by at least one cable modem communicatively coupled to both the upstream receiver hub and the downstream transmitter hub via cable modem network plant.
摘要:
A cable modem communication system includes a plurality of Cable Modems (CMs), a CM network segment, and a Cable Modem Termination System (CMTS). The CMTS segregates the plurality of CMs into a first group of CMs with which standard registering and ranging operations are performed and a second group of CMs with which attenuated transmission registering and ranging operations are performed. Each CM of the first group of CMs operable to perform registering and ranging operations by transmitting a ranging burst of a first format. Each CM of the second group of CMs operable to perform registering and ranging operations by transmitting a ranging burst of a second format that differs from the ranging burst of the first format. The CMTS may include a rake receiver that receives and demodulates a plurality of multi-path copies of the ranging burst of the second format.
摘要:
A filter settings generation operation includes sampling a communication channel to produce a sampled signal. The sampled signal is spectrally characterized across a frequency band of interest to produce a spectral characterization of the sampled signal. This spectral characterization may not include a signal of interest. The spectral characterization is then modified to produce a modified spectral characterization. Filter settings are then generated based upon the modified spectral characterization. Finally, the communication channel is filtered using the filter settings when the signal of interest is present on the communication channel. In modifying the spectral characterization, pluralities of spectral characteristics of the spectral characterization are independently modified to produce the modified spectral characterization. Modifications to the spectral characterization may be performed in the frequency domain and/or the time domain. One particular spectral modification that is performed is raising of the noise floor of the spectral characterization to meet a budgeted signal-to-noise ratio. Other spectral modifications include modifying spectral components corresponding to an expected interfering signal. In modifying these spectral characterizations, spectral components corresponding to a plurality of expected interfering signals may be modified.
摘要:
A filter settings generation operation includes sampling a communication channel to produce a sampled signal. The sampled signal is spectrally characterized across a frequency band of interest to produce a spectral characterization of the sampled signal. This spectral characterization may not include a signal of interest. The spectral characterization is then modified to produce a modified spectral characterization. Filter settings are then generated based upon the modified spectral characterization. Finally, the communication channel is filtered using the filter settings when the signal of interest is present on the communication channel. In modifying the spectral characterization, pluralities of spectral characteristics of the spectral characterization are independently modified to produce the modified spectral characterization. Modifications to the spectral characterization may be performed in the frequency domain and/or the time domain. One particular spectral modification that is performed is raising of the noise floor of the spectral characterization to meet a budgeted signal-to-noise ratio. Other spectral modifications include modifying spectral components corresponding to an expected interfering signal. In modifying these spectral characterizations, spectral components corresponding to a plurality of expected interfering signals may be modified.
摘要:
Characterization and assessment of communication channel average group delay variation. A signal having repeated signal components therein is received by a communication device, and that signal undergoes appropriate processing to determine respective amplitude and phase of a number of frequency bins. The phase difference from bin to bin (including respecting unwrapping, and proper normalization) is used to determine the group delay of a communication channel, or portion thereof, as a function of frequency. Multiple respective group delay measurements may be averaged to generate a wideband group delay of the communication channel as a function of frequency. Overlap between different respective band-edge portions of the communication channel may assist in generating a seamless continuous wideband spectrum estimation for use in determining the wideband group delay of the communication channel.
摘要:
A filter settings generation operation includes sampling a communication channel to produce a sampled signal. The sampled signal is spectrally characterized across a frequency band of interest to produce a spectral characterization of the sampled signal. This spectral characterization may not include a signal of interest. The spectral characterization is then modified to produce a modified spectral characterization. Filter settings are then generated based upon the modified spectral characterization. Finally, the communication channel is filtered using the filter settings when the signal of interest is present on the communication channel. In modifying the spectral characterization, pluralities of spectral characteristics of the spectral characterization are independently modified to produce the modified spectral characterization. Modifications to the spectral characterization may be performed in the frequency domain and/or the time domain. One particular spectral modification that is performed is raising of the noise floor of the spectral characterization to meet a budgeted signal-to-noise ratio. Other spectral modifications include modifying spectral components corresponding to an expected interfering signal. In modifying these spectral characterizations, spectral components corresponding to a plurality of expected interfering signals may be modified.
摘要:
Upstream burst noise measurement and characterization. One or more communication devices is implemented to detect and measure burst noise event(s) within channel(s) associated with communication link(s) within communication system(s) or network(s). Detection and measurement of a burst noise event may be made during active communications on one or more other channels, and may be made during active communications on two channels respectively adjacent to the channel on which the burst noise event is being detected and measured. The channel on which the burst noise event is detected and measured may be an unused channel. The detection and measurement of the burst noise event may be made during a quiet time slot within one of the channels. Correlation (e.g., with respect time) may be determined with respect to different respective layers within a communication device (e.g., with respect to MAC and PHY layers).
摘要:
A filter settings generation operation includes sampling a communication channel to produce a sampled signal. The sampled signal is spectrally characterized across a frequency band of interest to produce a spectral characterization of the sampled signal. This spectral characterization may not include a signal of interest. The spectral characterization is then modified to produce a modified spectral characterization. Filter settings are then generated based upon the modified spectral characterization. Finally, the communication channel is filtered using the filter settings when the signal of interest is present on the communication channel. In modifying the spectral characterization, pluralities of spectral characteristics of the spectral characterization are independently modified to produce the modified spectral characterization. Modifications to the spectral characterization may be performed in the frequency domain and/or the time domain. One particular spectral modification that is performed is raising of the noise floor of the spectral characterization to meet a budgeted signal-to-noise ratio. Other spectral modifications include modifying spectral components corresponding to an expected interfering signal. In modifying these spectral characterizations, spectral components corresponding to a plurality of expected interfering signals may be modified.