Abstract: The present disclosures describes a communication method, a CMTS, and a CM. The communication method includes: sending, by a CMTS, a reference signal within a first time period by using a valid subcarrier in a first spectrum, where the first time period is a time period within which none of CMs connected to the CMTS sends a signal in the first spectrum; performing, by the CMTS based on an interfering signal received by the CMTS within the first time period, channel interference estimation on a channel that is used during signal reception of the CMTS and that occupies the first spectrum, where the interfering signal is a signal obtained after the reference signal passes through the channel; and canceling, by the CMTS based on a result of the channel interference estimation, interference from a first signal received by the CMTS to a second signal received by the CMTS.

Abstract: A method, system, and apparatus for calibration for cable modem (CM) echo cancellation (EC) training in full duplex (FDX) coaxial networks is provided. A CM receives a current resource block assignment message (RBA) from a cable modem termination system (CMTS), and determines if designated channels available for assignment as downstream (DS) channels or upstream (US) channels have changed assignment values from a previously received RBA, and if EC training has been performed on the designated channels for the current RBA. If the designated channels have changed assignment values and EC training has not been performed on the designated channels for the current RBA, the CM performs EC training on the designated channels for the current RBA.

Abstract: A method and an apparatus for determining a time offset are disclosed. The method includes: obtaining, by a device at a head end, a time-domain signal based on a received signal; and then determining a time offset based on values of peak-to-average ratios of a preset quantity of symbols starting from a qth symbol in the time-domain signal, where a peak-to-average ratio of the qth symbol is greater than a preset threshold. A new method for determining a time offset is provided, and takes advantages that the time-domain signal obtained by the device at the head end has stronger capabilities of resisting interference such as frequency offset and phase noise. The method for determining a time offset can be applied both to initial ranging and periodic ranging.

Abstract: An echo cancellation training method in a cable modern is provided, comprising receiving an echo cancellation service ID (EC SID) assigned for echo cancellation training, the cable modem receiving the EC SID from a cable head end in an information element (IE) in a map (MAP or P-MAP) defining a time and frequency of upstream transmission opportunities for the cable modem, the EC SID establishing when the cable modem may perform the echo cancellation training in a downstream channel allocated to the cable modem, transmitting an echo cancellation test signal upstream to the cable head end via an upstream channel allocated to the cable modem and in a time slot specified by the received EC SID in the map, and measuring noise in one or more downstream channels allocated to the cable modem, with the noise resulting from the transmission of the echo cancellation test signal on the upstream channel.

Abstract: A central access network unit comprising a processor configured to assign a plurality of upstream training blocks from an upstream OFDM symbol to a plurality of downstream network units, wherein the OFDM symbol comprises a plurality of pilot subcarriers equally spaced across an upstream RF spectrum in a pre-determined time interval, and wherein each upstream training block comprises a different subset of the pilot subcarriers that are non-consecutive and situated across the upstream RF spectrum, and generate one or more messages comprising assignments of the upstream training blocks, and a transmitter coupled to the processor and configured to transmit the messages to the plurality of downstream network units via a network, wherein the messages instruct at least one of the plurality of downstream network units to transmit a modulated pre-determined sequence at the pilot subcarriers corresponding to the upstream training block assigned to the downstream network unit.

Abstract: Embodiments of the present invention provide a multicast profile switching method. In the method, using a multicast profile management module, a multicast profile switching request message is received from a cable modem termination system CMTS. A multicast profile having a maximum rate and commonly supported by all current multicast group members is determined. When the multicast profile having the maximum rate is different from a current multicast profile that is running, a multicast profile switching instruction is sent to the CMTS, where the multicast profile switching instruction is used to instruct the CMTS to perform multicast profile switching.

Abstract: Embodiments of the present disclosure provide an FEC coding and decoding method and device, and a system. A transmit end determines a forward error correction FEC coding type according to a length of to-be-coded data in burst data, and performs coding according to the determined FEC coding type. A receive end determines a forward error correction FEC decoding type according to a length of to-be-decoded data in burst data, and performs decoding according to the determined FEC decoding type. The FEC coding and decoding method provided in the embodiments of the present disclosure improves utilization of a communication resource is improved, and saves a communication resource.

Abstract: Disclosed herein is a multi-stage echo cancelation scheme. The disclosed embodiments include an apparatus and method for monitoring and canceling echoes greater than 25 dB in a coaxial cable plant. The method includes obtaining echo channel estimate coefficients from a cable node. The method determines a location and strength of each partial echo in an impulse response using the echo channel estimate coefficients. Optionally, the method determines a frequency response of each partial echo in the impulse response.

Abstract: A central access network unit comprising a processor configured to assign a plurality of upstream training blocks from an upstream OFDM symbol to a plurality of downstream network units, wherein the OFDM symbol comprises a plurality of pilot subcarriers equally spaced across an upstream RF spectrum in a pre-determined time interval, and wherein each upstream training block comprises a different subset of the pilot subcarriers that are non-consecutive and situated across the upstream RF spectrum, and generate one or more messages comprising assignments of the upstream training blocks, and a transmitter coupled to the processor and configured to transmit the messages to the plurality of downstream network units via a network, wherein the messages instruct at least one of the plurality of downstream network units to transmit a modulated pre-determined sequence at the pilot subcarriers corresponding to the upstream training block assigned to the downstream network unit.

Abstract: Embodiments of the present disclosure provide an FEC coding and decoding method and device, and a system. A transmit end determines a forward error correction FEC coding type according to a length of to-be-coded data in burst data, and performs coding according to the determined FEC coding type. A receive end determines a forward error correction FEC decoding type according to a length of to-be-decoded data in burst data, and performs decoding according to the determined FEC decoding type. The FEC coding and decoding method provided in the embodiments of the present disclosure improves utilization of a communication resource is improved, and saves a communication resource.

Abstract: Provided are a method and an apparatus for canceling interference, to resolve a problem that performance of interference cancellation is poor because accuracy of equalizer coefficients obtained by a CMTS through calculation is not sufficiently high. A specific solution is as follows: (101) A CMTS calculates L equalizer coefficients of an L-tap filter according to a preamble sequence by using an adaptive algorithm, and performs adaptive equalization on a received signal by using the L equalizer coefficients, where L is a positive integer greater than 24; and (102) the CMTS selects K equalizer coefficients from the L equalizer coefficients, and sends a ranging response message carrying the K equalizer coefficients to a cable modem CM, so that the CM performs pre-equalization on a to-be-sent signal according to the received K equalizer coefficients, where K is a positive integer less than or equal to L.

Abstract: A system for cable network communications is provided, comprising a cable modem termination system (CMTS), a trunk cable coupled to the CMTS, cable modems (CMs) divided into at least a low frequency CM group and a high frequency CM group positioned between the CMTS and the low frequency CM group, one or more second taps attached to the trunk cable, with corresponding second drop cables coupled to one or more corresponding CMs of the low frequency CM group, and a first duplexer tap attached to the trunk cable between the CMTS and the one or more second taps, with a corresponding first drop cable coupled to a CM of the high frequency CM group. The first duplexer tap receives an input signal and provides a low frequency signal to the low frequency CM group and a high frequency signal to the high frequency CM group.

Abstract: The present invention provides a preamble sequence sending and receiving method and apparatus, and a system. The preamble sequence sending method includes: generating, by a transmit end, a frequency offset estimation sequence, where the frequency offset estimation sequence includes N subsequences each with a length of M, N is a positive integer greater than or equal to 2, and M is a positive integer; generating, by the transmit end, a prefix and a suffix based on the frequency offset estimation sequence; adding, by the transmit end, the prefix and the suffix before and after the frequency offset estimation sequence respectively to form a preamble sequence, where the prefix and the suffix are used for canceling multipath interference; and adding, by the transmit end, the preamble sequence to a data packet and sending the data packet to a receive end.

Abstract: An apparatus, comprising a receiver configured to receive a primary signal that comprises a narrowband noise component and a broadband noise component, a processor coupled to the receiver and configured to determine, in a time domain, an estimate of the narrowband noise component in real-time, determine a cancelled output signal in real-time that comprises an estimate of the broadband noise component, and determine an estimate of a power level of the narrowband noise component in real-time.

Abstract: Provided are a method and an apparatus for canceling interference, to resolve a problem that performance of interference cancellation is poor because accuracy of equalizer coefficients obtained by a CMTS through calculation is not sufficiently high. A specific solution is as follows: (101) A CMTS calculates L equalizer coefficients of an L-tap filter according to a preamble sequence by using an adaptive algorithm, and performs adaptive equalization on a received signal by using the L equalizer coefficients, where L is a positive integer greater than 24; and (102) the CMTS selects K equalizer coefficients from the L equalizer coefficients, and sends a ranging response message carrying the K equalizer coefficients to a cable modem CM, so that the CM performs pre-equalization on a to-be-sent signal according to the received K equalizer coefficients, where K is a positive integer less than or equal to L.

Abstract: The present invention provides a preamble sequence sending and receiving method and apparatus, and a system. The preamble sequence sending method includes: generating, by a transmit end, a frequency offset estimation sequence, where the frequency offset estimation sequence includes N subsequences each with a length of M, N is a positive integer greater than or equal to 2, and M is a positive integer; generating, by the transmit end, a prefix and a suffix based on the frequency offset estimation sequence; adding, by the transmit end, the prefix and the suffix before and after the frequency offset estimation sequence respectively to form a preamble sequence, where the prefix and the suffix are used for canceling multipath interference; and adding, by the transmit end, the preamble sequence to a data packet and sending the data packet to a receive end.

Abstract: An apparatus, method, and computer program product are provided for communicating one or more symbols with multiple pilot signals and nulls. In use, one or more symbols are communicated including a plurality of pilot signals and a plurality of nulls, for use in generating a plurality of coefficients.

Abstract: An apparatus, comprising a receiver configured to receive a primary signal that comprises a narrowband noise component and a broadband noise component, a processor coupled to the receiver and configured to determine, in a time domain, an estimate of the narrowband noise component in real-time, determine a cancelled output signal in real-time that comprises an estimate of the broadband noise component, and determine an estimate of a power level of the narrowband noise component in real-time.

Abstract: A central access network unit comprising a processor configured to assign a plurality of upstream training blocks from an upstream OFDM symbol to a plurality of downstream network units, wherein the OFDM symbol comprises a plurality of pilot subcarriers equally spaced across an upstream RF spectrum in a pre-determined time interval, and wherein each upstream training block comprises a different subset of the pilot subcarriers that are non-consecutive and situated across the upstream RF spectrum, and generate one or more messages comprising assignments of the upstream training blocks, and a transmitter coupled to the processor and configured to transmit the messages to the plurality of downstream network units via a network, wherein the messages instruct at least one of the plurality of downstream network units to transmit a modulated pre-determined sequence at the pilot subcarriers corresponding to the upstream training block assigned to the downstream network unit.

Abstract: An apparatus, method, and computer program product are provided for communicating one or more symbols with multiple pilot signals and nulls. In use, one or more symbols are communicated including a plurality of pilot signals and a plurality of nulls, for use in generating a plurality of coefficients.