Patent ID: 9130676
Filing Date: 2015-09-08
Classification: H04B,H04J,H04Q

Abstract:
1. A method for performing a switch operation between a first Optical Line Terminal OLT and a second OLT in a Passive Optical Network PON, said first and second OLTs being connected to a plurality of Optical Network Units ONUs through at least one splitter, said first OLT and said second OLT being arranged to allocate resources to the plurality of ONUs by sending GATE messages, the first OLT being by default in charge of sending GATE messages, the resources are used by respective ONUs to transmit data or REPORT messages, each ONU of the plurality of ONUs being by default in a registered state in which the ONU is allowed to send REPORT messages or data, after allocation of resources, to said ONU, the REPORT message being sent to the first or the second OLT in order to require resource allocations, each REPORT message being time stamped by the ONU with a first timestamp, said first timestamp representing the local time at which the REPORT message is sent, each given ONU being adapted to be switched in a deregistered state by a given OLT when, upon reception by the given OLT of a REPORT message from said given ONU, a difference between a current Round Trip Time RTT and a previous RTT is greater than a first threshold of the given OLT, said current RTT being determined based on the first timestamp of the REPORT message and a local clock time of the given OLT, and said previous RTT being an RTT determined for a previously received REPORT message, an ONU in a deregistered state being not allowed to transmit REPORT messages nor data to the first or second OLTs, the first threshold of the second OLT being initially set to a first initial value, wherein, to perform a switch between the first OLT and the second OLT for at least one first ONU of the plurality of ONUs, the method is performed by the second OLT and comprises: setting the first threshold of the second OLT to a value at least equal to a predefined maximum value; sending a GATE message to said first ONU to allocate resources to the first ONU; and after the reception of a REPORT message from the first ONU, setting the first threshold of the second OLT to the first initial value.