Double-sideband continuous wave test (CWT) tone signals for data over cable service interface specification (DOCSIS) full duplex (FDX) interference group discovery

A cable modem configured to measure receive modulation error from received signals, comprising

• a memory storing computer-readable instructions;
• and
• a processor configured to execute the computer-readable instructions to:
• receive, in a downstream direction in a full duplex (FDX) subband transmitting upstream continuous wave test (CWT) tone signals, a plurality of CWT tone signals offset from a group of scattered pilot signals by at least one predetermined positive offset frequency and at least one predetermined negative offset frequency based on fractional Orthogonal Frequency Division Multiplexing (OFDM) offset frequency spacing parameters;
• process the plurality of CWT tone signals to determine an average value of a Receive Modulation Error Ratio (RxMER) over a period of time;
• compare the average value of the RxMER over the period of time to a threshold of an interference group (IG) to measure receive modulation error;
• determine if the average value of the RxMER over the period of time is above a predetermined threshold;
• and
• assign the processor transmitting upstream CWT tone signals to the IG when the average value of the RxMER over the period of time is above the predetermined threshold, otherwise assign the processor upstream CWT tone signals to a different IG that provides Radio Frequency (RF) isolation to allow simultaneous upstream and downstream transmissions at a same frequency without interference.

A method for performing Full Duplex (FDX) interference discovery using double-sideband continuous wave test (CWT) sounding pilot tone signals, comprising:

• receiving, from a Cable Modem Termination System (CMTS), fractional Orthogonal Frequency Division Multiplexing (OFDM) offset frequency spacing parameters and locations of continuous wave test (CWT) tone signals relative to locations of scattered pilot signals across an OFDM channel;
• determining a group of scattered pilot signals for inserting, for interference group discovery, a plurality of continuous wave test (CWT) tone signals at the locations of the CWT tone signals relative to the locations of the scattered pilot signals in the determined group of scattered pilot signals, the plurality of CWT tone signals offset from each of the scattered pilot signals by at least one predetermined positive offset frequency and at least one predetermined negative offset frequency based on the fractional OFDM offset frequency spacing parameters;
• and
• transmitting, in an upstream full duplex (FDX) subband, the plurality of CWT tone signals offset from the locations of the scattered pilot signals in the determined group of scattered pilot signals by the at least one predetermined positive offset frequency and the at least one predetermined negative offset frequency.