Patent ID: 8700805
Filing Date: 2014-04-15
Classification: H04J,H04W

Abstract:
1. A method for synchronizing clocks in a communication network, wherein a first clock of a first network element is used for synchronizing at least one second clock of one or more second clocks of one or more second network elements, comprising: the first network element sending a plurality of first messages to one of the second network elements, each of the first messages having a first counter identifying a time of the first clock at which the first message was sent by the first network element, each of the first messages being a synchronization message to synchronize the first clock with the second clock of the second network element; the second network element receiving each of the first messages; in response to receiving each of the first messages, the second network element recording a time of the second clock corresponding to when the first message was received by the second network element as a first message received time value; the second network element saving the first counter of the first message for each of the received first messages; the second network sending a plurality of second messages to the first network element, each of the second messages identifying a second counter to identify a time of the second clock at which the second network element sent the second message; the second network element saving the second counter for each second message; the first network element receiving each of the second messages; in response to the second messages, the first network element sending a plurality of third messages, each of the third messages sent in response to a respective one of the second messages received by the first network element, each of the third messages having a third value identifying a value of the first clock at a time the first network element received the second message; the second network element receiving each of the third messages from the first network element; the second network element saving the third value of the third message for each of the received third messages; the second network element applying a filtering method to filter data from the first messages and third messages for determining a line delay affecting communications between the first and second network elements, the filtering method comprising: the second network element estimating the line delay in an estimation calculation comprising: the second network element applying the determined line delay to time information communicated by the first network element to synchronize the second clock with the first clock.