Methods and devices for wavelength alignment in WDM-PON

A passive optical network system comprising at least one optical network unit and an optical line terminal, the system configured to:

• set an initial value of an upstream wavelength (wUS) for an upstream signal (US) from the optical network unit to the optical line terminal,
• iteratively perform the following until an iteration criterion is met:
• i) transmit the upstream signal (US) from the optical network unit to the optical line terminal,
• ii) measure, at the optical line terminal, a power level of the received upstream signal (US),
• iii) transmit from the optical line terminal to the optical network unit power level data (p) indicative of the measured power level, and
• iv) set, at the optical network unit, the upstream wavelength (wUS) for the upstream signal (US) to a wavelength-value, and as a function of a set of power level data associated with a respective upstream wavelength;
• and
• select, at the optical network unit, autonomous from the optical line terminal, the upstream wavelength (wUS) to one of the wavelength-values previously set during the iteratively performing and associated with one of the set of power level data corresponding to a certain power level.

A method in an optical network unit of a passive optical network, the method comprising:

• setting an initial value of an upstream wavelength (wUS) for an upstream signal (US) from the optical network unit to an optical line terminal,
• iteratively performing the following until an iteration criterion is met:
• i) transmitting the upstream signal (US) to the optical line terminal,
• ii) receiving from the optical line terminal power level data (p) for the upstream signal (US) as measured by the optical line terminal, and
• iii) setting the upstream wavelength (wUS) to a wavelength-value, and as a function of a set of power level data associated with a respective upstream wavelength;
• and
• selecting, autonomous from the optical line terminal, the upstream wavelength (wUS) to one of the wavelength-values previously set during the iteratively performing and associated with one of the set of power level data corresponding to a certain power level.

A method in the optical line terminal of the passive optical network of claim 17, the method comprising:

• receiving, from the optical network unit of claim 19, the upstream signal (US) having an upstream wavelength (WUS), the method further comprising:
• i) continuously receiving the upstream signal (US) from the optical network unit,
• ii) continuously measuring a power level of the received the upstream signal (US), and
• iii) continuously transmitting to the optical network unit power level data (p) indicative of the measured power level.

A method in a passive optical network system comprising at least one optical network unit and an optical line terminal, the method comprising:

• setting an initial value of an upstream wavelength (wUS) for an upstream signal (US) from the optical network unit to the optical line terminal,
• iteratively performing the following until an iteration criterion is met:
• i) transmitting the upstream signal (US) from the optical network unit to the optical line terminal,
• ii) measuring, at the optical line terminal, a power level of the received the upstream signal (US),
• iii) transmitting from the optical line terminal to the optical network unit power level data (p) indicative of the measured power level, and
• iv) setting, at the optical network unit, the upstream wavelength (wUS) for the upstream signal (US) to a wavelength-value, and as a function of a set of power level data associated with a respective upstream wavelength;
• and
• selecting, at the optical network unit, autonomous from the optical line terminal, the upstream wavelength to be one of the wavelength-values previously set during the iteratively performing and associated with one of the set of power level data corresponding to a certain power level.