| 摘要 |
<P>PROBLEM TO BE SOLVED: To realize time synchronization of a slave device such as a base station relative to a master device such as an L2SW or a base station in a communication system employing a PON. <P>SOLUTION: Time information acquired from a GPS satellite 3 is reflected to time information of an ONU6 by correcting the time information acquired from the GPS satellite 3 based on ranging information of a discovery function of an OLT4. A communication system calculates a propagation delay from an L2SW2 to the ONU6 by calculating a propagation delay from the L2SW2 to the OLT4 by means of a delay estimation mechanism, and adding a propagation delay from the OLT4 to the ONU6 obtained by ranging to it. By adding the calculated propagation delay from the L2SW2 to the ONU6 to a transmitted time stamp value, the time stamp value received by a base station 7 or a femtocell 8 includes the propagation delay to the ONU6, which makes it possible to synchronize a clock time timer by an absolute value. This addition processing can be realized by rewriting the time stamp value of a packet in the internal of the OLT4 or ONU6. <P>COPYRIGHT: (C)2012,JPO&INPIT |
