Patent ID: 7130268
Filing Date: 2006-10-31
Classification: H04L,H04W,Y02D

Abstract:
1. In an end-to-end estimation method of bandwidth available in a connection of a client and server established over a packet switching network, the improvements comprising: computing in a first routine samples of the bandwidth available by taking into account a flow of data packets received by the client and time intervals during which the data packets are received if the routine is implemented at a receiver side of the client, or by taking into account acknowledgments or report packets received by a sender side of the server and time intervals during which acknowledgment or report packets are received if the routine is implemented at the sender side of the server; computing in a second routine samples of available bandwidth as a ratio of an amount of received data packets over the time intervals during which the data packets are received if the routine is implemented at the receiver side of the client, or as a ratio of an amount of the data packets acknowledged over the time intervals during which the data packets are acknowledged if the routine is implemented at the sender side of the server; and implementing in a third routine a discrete time low-pass filter to obtain a filtered value of the samples of the available bandwidth, wherein a sample of the bandwidth available b where d j is the amount of the received data packets that have been received at the receiver side of the client or acknowledged at the sender side of the server in an interval t j −t j−1 , t j−1 is a time when a previous ACK or an ACK of one or more congestion windows of packets before were received by the sender side of the server or a time when a previous packet or a packet one or more congestion windows of packets before were received by the receiver side of the client, and t j is a time when a current ACK is received by the sender side of the server or when a current packet is received by the receiver side of the client, and wherein the available bandwidth samples are averaged using the discrete-time low-pass filter with time-varying coefficients: where {overscore (b)} j is the filtered measurement of the available bandwidth at time t=t j , {circumflex over (b)} j−1 is the filtered measurement of the available bandwidth at time t j−1 , Δ j =t j −t j−1 , 1/τ f is the cut-off frequency of the filter, b j is the sample of the available bandwidth at time t j , and b j−1 is the sample of the available bandwidth at time t j−1 if a time t/m (m≧2) has elapsed since the last received ACK or packet without receiving any new ACK or packet, then the filter assumes the reception of a virtual sample b j =0.