An optical line termination for communicating over an optical communication network with plural optical network units (111, 112, 113, 114), said optical line termination comprising: - a transmitter configured to transmit downstream optical signals to said optical network units (111, 112, 113, 114) using time division and/or wavelength division multiplexing; - a receiver configured to receive upstream optical signals from said optical network units (111, 112, 113, 114) using time division and/or wavelength division multiplexing in full duplex operation with said transmitter; CHARACTERISED IN THAT said optical line termination further comprises: - a scheduler configured to: - group said optical network units (111, 112, 113, 114) in at least a first group of optical network units (111, 112) whose optical loss budget across said optical communication network is smaller than an optical loss limit and a second group of optical network units (113, 114) whose optical loss budget across said optical communication network is greater than said optical loss limit; - control said transmitter to transmit downstream optical signals at a first transmit power in a first time interval and/or at a first wavelength, and allow only optical network units (111, 112) of said first group to transmit upstream optical signals in said first time interval and/or at said first wavelength; and - control said transmitter to transmit downstream optical signals at a second transmit power, smaller than said first transmit power, in a second time interval and/or at a second wavelength, and allow optical network units (113, 114) of said second group to transmit upstream optical signals in said second time interval and/or at said second wavelength. - a transmitter configured to transmit downstream optical signals to said optical network units (111, 112, 113, 114) using time division and/or wavelength division multiplexing; - a receiver configured to receive upstream optical signals from said optical network units (111, 112, 113, 114) using time division and/or wavelength division multiplexing in full duplex operation with said transmitter; CHARACTERISED IN THAT said optical line termination further comprises: - a scheduler configured to: - group said optical network units (111, 112, 113, 114) in at least a first group of optical network units (111, 112) whose optical loss budget across said optical communication network is smaller than an optical loss limit and a second group of optical network units (113, 114) whose optical loss budget across said optical communication network is greater than said optical loss limit; - control said transmitter to transmit downstream optical signals at a first transmit power in a first time interval and/or at a first wavelength, and allow only optical network units (111, 112) of said first group to transmit upstream optical signals in said first time interval and/or at said first wavelength; and - control said transmitter to transmit downstream optical signals at a second transmit power, smaller than said first transmit power, in a second time interval and/or at a second wavelength, and allow optical network units (113, 114) of said second group to transmit upstream optical signals in said second time interval and/or at said second wavelength. - group said optical network units (111, 112, 113, 114) in at least a first group of optical network units (111, 112) whose optical loss budget across said optical communication network is smaller than an optical loss limit and a second group of optical network units (113, 114) whose optical loss budget across said optical communication network is greater than said optical loss limit; - control said transmitter to transmit downstream optical signals at a first transmit power in a first time interval and/or at a first wavelength, and allow only optical network units (111, 112) of said first group to transmit upstream optical signals in said first time interval and/or at said first wavelength; and - control said transmitter to transmit downstream optical signals at a second transmit power, smaller than said first transmit power, in a second time interval and/or at a second wavelength, and allow optical network units (113, 114) of said second group to transmit upstream optical signals in said second time interval and/or at said second wavelength.