Patent ID: 8923128

Claim:
A method in a receiving node for detecting congestion in a communications network to which the receiving node is connected, the method comprising: receiving data packets from a sending node through the communications network over a communications link in a session, which data packets arrive at the receiving node with a time delay, which time delay has a frequency spectrum that is dependent on a load level of the communications network; determining a first part of the frequency spectrum that is limited upwards by a lower frequency limit, so that the first part of the frequency spectrum comprises non-congestion related low frequency components but substantially no congestion related low frequency components; determining a second part of the frequency spectrum that is limited upwards by an upper frequency limit, so that, when the load level of the communications network is below a threshold value, the second part of the frequency spectrum comprises non-congestion related low frequency components, but substantially no congestion related low frequency components and so that, when the load level of the communications network is above the threshold value, the second part of the frequency spectrum comprises non-congestion related low frequency components and congestion related low frequency components; estimating a reference jitter level corresponding to the first part of the frequency spectrum and a congestion jitter level corresponding to the second part of the frequency spectrum; and determining congestion state information of said communications network by comparing said congestion jitter level to said reference jitter level.