An optical network unit , abbreviated ONU, for downstream data reception in a passive optical network , abbreviated PON, of a first data frame stream sent by an optical line termination , abbreviated OLT, wherein said first data frame stream is converted into a second data frame stream by propagation from said OLT to said ONU along a dispersive communication channel comprised in said PON , wherein said ONU comprises: - a receiver configured to process said second data frame stream , wherein said second data frame stream comprises samples positioned at sample indices along data frames of said second data frame stream ; - a correlation determining unit configured to determine for each sample index a correlation value between a sequence of samples around a sample with said sample index and a predetermined sequence of symbols indicative of a frame boundary of a data frame in said first data frame stream ; CHARACTERIZED IN THAT said ONU further comprises: - a hunting unit configured to identify a sample index corresponding to a correlation value with largest absolute value, thereby: o detecting frame boundaries of said data frames within said second data frame stream and thereby synchronizing said ONU with said OLT ; and o estimating the coefficient with largest absolute value of a channel impulse response of said dispersive communication channel and thereby providing a channel estimation of said dispersive communication channel ; and - a training unit configured to, when said hunting unit synchronizes said ONU with said OLT and when said training unit receives said channel estimation from said hunting unit , configure an equalizer in accordance with said channel estimation for said downstream data reception. - a receiver configured to process said second data frame stream , wherein said second data frame stream comprises samples positioned at sample indices along data frames of said second data frame stream ; - a correlation determining unit configured to determine for each sample index a correlation value between a sequence of samples around a sample with said sample index and a predetermined sequence of symbols indicative of a frame boundary of a data frame in said first data frame stream ; - a hunting unit configured to identify a sample index corresponding to a correlation value with largest absolute value, thereby: o detecting frame boundaries of said data frames within said second data frame stream and thereby synchronizing said ONU with said OLT ; and o estimating the coefficient with largest absolute value of a channel impulse response of said dispersive communication channel and thereby providing a channel estimation of said dispersive communication channel ; and o detecting frame boundaries of said data frames within said second data frame stream and thereby synchronizing said ONU with said OLT ; and o estimating the coefficient with largest absolute value of a channel impulse response of said dispersive communication channel and thereby providing a channel estimation of said dispersive communication channel ; and - a training unit configured to, when said hunting unit synchronizes said ONU with said OLT and when said training unit receives said channel estimation from said hunting unit , configure an equalizer in accordance with said channel estimation for said downstream data reception. <EOS>