Patent ID: 9401995
Filing Date: 2016-07-26
CPC Classification: H04L,H04M

Claim Text:
1. A method for echo cancellation, comprising: marking respective source signals with a respective marker signal to identify respective starting time references of said respective source signals and to identify respective transmitters to transmit respectively obtained marked source signals; transmitting the respectively marked source signals by said respective transmitters to at least one aggregate node; summing the respective marked source signals received by said at least one aggregate node to create a multicast signal for provision, via a multicast node, to respective receivers associated to the respective transmitters; determining respective round trip power normalization and round trip delay values for modifying, in said respective receivers, said respective marked source signals to obtain respective delayed and normalized respective marked source signals, wherein the respective round trip normalization value is determined as the amount of transmitters participating in a call as a consequence of the summation process in the at least one aggregation node, and wherein the respective round trip delay value is determined by comparing said multicast signal with the respective marker signal but shifted to a certain variable delay, such that when both markers coincide, the delay is determined; and subtracting, at said respective receivers, the respective round trip delayed and normalized marked source signal from said multicast signal to obtain respective echo cancelled multicast signals in said respective receivers.