An Optical Access Network, a Optical Network Unit (ONU) and various methods for exchanging information are provided. The method may include : receiving, by the ONU, a pilot signal and downstream information signals; wherein the pilot signal is received at a pilot frequency slot and the downstream information signals are received at a downstream information frequency slot; wherein the ONU is allocated with a spectral slice that comprises the pilot frequency slot, the downstream information frequency slot, a guard frequency slot and an upstream information frequency slot; wherein at least one other spectral slice is allocated for exchanging information with at least one other group of ONUs; splitting the downstream information signals to downstream information signals portions; splitting the pilot signals to pilot signals portions; detecting downstream information, in response to at least a first portion of downstream information signals; modulating a portion of the pilot signal by upstream information signals to provide upstream information signals that are within the upstream information frequency slot; modulating a second portion of the downstream information signals by the upstream information signals to provide upstream secondary signals that are outside the pilot frequency slot, the downstream information frequency slot and the upstream information frequency slot; and upstream transmitting the upstream information signals and the upstream secondary signals.