Patent ID: 8270393

Claim:
At a remote access device located between a central office and a customer premise equipment in a digital subscriber line system, a method for adjusting power spectrum density of an output signal for the remote access device in order to improve spectral compatibility, allow flexibility of spectrum settings, and improve transmission performance, the method comprising: obtaining a power spectrum density of a signal transmitted from a central office access device to a customer premise equipment, wherein the power spectrum density is determined at a remote access device located between the central office and the customer premise equipment; identifying a portion of the spectrum of the output signal of the remote access device that overlaps with a portion of a spectrum signal transmitted by the central office access device; based on the identified overlapping portion, adjusting the power spectrum density of the output signal of the portion of the spectrum overlapping with the portion of the spectrum of the signal transmitted by the central office access device according to the power spectrum density of the signal transmitted from the central office access device to the customer premise equipment; wherein obtaining the power spectrum density of the signal transmitted from the central office access device to the customer premise equipment comprises: obtaining a distance between the remote access device and the central office access device; obtaining a line transfer function illustrating a relationship between line attenuation and frequency; wherein the line transfer function is Attenu(i) (dB/km), the distance between the central office and the remote office is L, the signal is transmitted by means of nominal TX power of tone(i), the power spectrum density of signal transmitted by the central office access device at the remote access device is PSDco-rt(i), and wherein the PSDco-rt(i)=10 log TX power of tone(i)−L×Attenu(i); obtaining a nominal power spectrum density of the central office access device; and obtaining the power spectrum density of the signal transmitted from the central office access device to the customer premise equipment at a measured point between the central office and the customer premise equipment according to the distance, the line transfer function, and the nominal power spectrum density of the central office access device.