Method and device for resident time calculation and synchronization

摘要

The embodiments herein relate to a method in a communications network comprising a communications link connecting a first device to a second device. The communications link comprises an upper layer having a variable delay and a lower layer having a constant delay. The first device comprises a first clock and the second device comprises a second clock. The communications network synchronizes the first clock via the lower layer of the communications link with the second clock. The communications network determines, at the second device, a residence time for a first message when transmitted from the first device to the second device via the upper layer of the communications link.

主权项

1. A method in a communications network comprising a communications link connecting a first device to a second device, wherein the communications link comprises an upper layer having a variable delay and a lower layer having a constant delay, wherein the first device comprises a first clock and the second device comprises a second clock, the method comprising:
synchronizing the first clock via the lower layer of the communications link with the second clock; and determining, at the second device, a residence time for a fifth message when transmitted from the first device to the second device via the upper layer of the communications link, wherein the first device further comprises a third clock and the second device comprises a fourth clock, wherein the third clock is a replica of the fourth clock, and wherein the determining, at the second device, the residence time for the fifth message when transmitted from the first device to the second device via the upper layer of the communications link further comprises:
determining at the first device, an eleventh time stamp using the third clock for the transmission of the fifth message from the first device to the second device;determining, at the second device, a twelfth time stamp using the fourth clock, which twelfth time stamp is associated with the receipt of the fifth message at the second device; anddetermining, at the second device, a second difference between the twelfth time stamp and the eleventh time stamp; andwherein the fifth message further comprises the eleventh time stamp.