In-Service Pre-Ranging for Upstream ONU Activation in Low-Latency TDM-PON Using Downstream Data Only

We demonstrate an upstream-traffic-interruption-free ranging method for low-latency TDM-PON, which measures relative delay of a copropagating strobe to the downstream signal to derive appropriate ONU start time for the upstream burst transmission. Experimental results show pre-ranging accuracy to be
$< 10-\mu s$
.