Communication system, communication apparatus and time synchronization method

摘要

A communication system that is constituted by a plurality of communication apparatuses, and performs time synchronization using a time synchronization frame, wherein one of the communication apparatuses is set as a starting point node, at least one of the communication apparatuses is set as a terminal point node, the starting point node generates a time synchronization frame in an outward-route direction and transmits the generated time synchronization frame in the outward-route direction, the terminal point node generates a time synchronization frame in a return-route direction and transmits the generated time synchronization frame in the return-route direction, and an intermediate node relays a received time synchronization frame when receiving a time synchronization frame transmitted in an outward-route direction and a return-route direction.

主权项

1. A communication system performing time synchronization using a time synchronization frame transmitted in an outward-route direction and a return-route direction, the communication system comprising:
a plurality of communication apparatuses, wherein the communication apparatuses constitute a ring network, one of the communication apparatuses that constitute the ring network is set as a starting point node, and one or more communication apparatuses among the communication apparatuses are set as terminal point nodes, the starting point node includes a starting-point-node transmitting unit that generates a time synchronization frame in an outward-route direction, and transmits the generated time synchronization frame in both directions of the ring network, and a time-information noticing unit that notices, to an intermediate node and the terminal point nodes, time information related to a time of transmission at which the time synchronization frame in the outward-route direction is transmitted and a time of reception at which a time synchronization frame in the return-route direction transmitted from the terminal point nodes is received, each of the one or more terminal point nodes includes a terminal-point-node transmitting unit that generates a time synchronization frame in the return-route direction, and transmits the generated time synchronization frame in a return-route direction, the intermediate node is a communication apparatus among the communication apparatuses other than the starting point node and the terminal point nodes and includes a relay unit that relays a received time synchronization frame to an adjacent node when receiving the time synchronization frame transmitted in the outward-route direction and when receiving the time synchronization frame transmitted in the return-route direction, and the intermediate node performs time synchronization of its own communication apparatus based on the time information noticed by the starting point node, a time of reception at which the time synchronization frame transmitted from the starting point node is received, and a time of transmitting at which the intermediate node relays a time synchronization frame transmitted from the terminal point nodes.