| 摘要 |
PCT No. PCT/FI95/00111 Sec. 371 Date Aug. 14, 1996 Sec. 102(e) Date Aug. 14, 1996 PCT Filed Feb. 28, 1995 PCT Pub. No. WO95/24800 PCT Pub. Date Sep. 14, 1995A method of hierarchical synchronization for a telecommunications system employing message-based synchronization, the system having a plurality of nodes interconnected by transmission lines, wherein the nodes interchange signals containing synchronization messages each having a synchronization signature indicating a priority of the corresponding signal in an internal synchronization hierarchy of the system, and wherein a node is forced to enter into a predetermined standard state in a change situation in order to prevent the selection of faulty synchronization messages. The method includes, in a change situation, the node entering into a state of forced timing where it has selected a synchronization signature received from a neighboring node and synchronized itself with a clock frequency of a signal from the neighboring node, and upon transition to the state of forced timing, measuring a time period with a timer, and then, after expiry of the time period, the node entering into a state of normal timing, and when the selected synchronization signature changes while in said state of forced timing, accepting the signature, and restarting measurement of the time period of the forced state, and when a quality of the signal corresponding to the selected synchronization signature becomes inadequate for synchronization, the node entering into the predetermined standard state in order to prevent the selection of a faulty synchronization signature, and restarting the measuring of the time period of the forced state, wherein a transition is performed at least whenever a signal is received from said neighboring node through only one transmission line.
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