A TIME SYNCHRONIZATION PROTOCOL FOR LONG RANGE UNDERWATER NETWORKS

摘要

The present invention relates to a method for accurate time-boundary time division multiple access of underwater acoustic network for maritime communications. A protocol for long range underwater communications between a command ship controlling communication network on sea and cluster headers underwater comprises the steps of: (a) broadcasting beacon in the form of packet train by the command ship; (b) receiving N number of packets in a row of the beacon and storing the time of receiving the packet by the cluster header; (c) obtaining an initial propagation delay time between the command ship and the cluster header by using the time of packet sending and the time of packet receiving by means of time stamp of medium access control; (d) estimating an initial clock skew by using a gap of received time of the received packet; (e) estimating time change of the propagation delay of the received packet by using the estimated initial clock skew; (f) calculating re-estimated clock skew and re-estimated clock offset by using the stored packet receiving time, the estimated initial clock skew, and the time change of the propagation delay; and (g) updating a local clock time of the cluster header when receiving packets by using the calculated re-estimated clock skew and the re-estimated clock offset.