Patent ID: 8488965

Claim:
A network system comprising: a first OLT (Optical Line Terminal), a second OLT, a first ONU (Optical Network Unit), and a second ONU, wherein the first OLT and the second OLT are connected to the first ONU and the second ONU through an optical fiber shared by the first OLT and the second OLT such that data is transmitted between the first OLT and the first ONU and between the second OLT and the second ONU, wherein the first OLT and the second OLT perform a ranging that measures a distance between the first OLT and the first ONU and between the second OLT and the second ONU by avoiding an uplink data transmission band of the first ONU and the second ONU, wherein the first OLT and the second OLT notify a timing performing the ranging to each other and the other OLT notified allocates a band to the first ONU or the second ONU by avoiding the timing performing the ranging, and wherein a difference of an equivalent delay between the first OLT and the second OLT is calculated based on the ranging results and the first OLT and the second OLT allocate the uplink data transmission band to the first ONU and the second ONU, respectively, based on the calculation results.