Patent ID: 7693077

Claim:
A method for estimating an available bandwidth of a network, the method comprising the steps of: transmitting a plurality of periodic time-stamp packets to a receiving-party communication apparatus, which is connected to the network, through the network at a currently-set test transmission rate; checking a changing tendency of transmission delay time differences between the time-stamp packets on the basis of a transmission time of each respective packet of the plurality of time stamped packets versus a reception time at which the receiving-party communication apparatus has received each of the respective time-stamp packets and determining whether the changing tendency of the delay time differences is increasing or decreasing; checking whether the transmission delay time differences between each respective transmitted and received packet is within an error range determined based on the error range determined being wider than a predetermined stable range; setting the currently-set test transmission rate to an exponentially decreased value when the transmission delay time differences are located outside the error range and show a tendency to increase; setting the currently-set test transmission rate to an exponentially increased value when the transmission delay time differences are located outside the error range and show a tendency to decrease; checking whether the transmission delay time differences are within the stable range when the transmission delay time differences are within the error range; setting the currently-set test transmission rate to a linearly decreased value when the transmission delay time differences are located outside the stable range and show a tendency to increase; setting the currently-set test transmission rate to a linearly increased value when the transmission delay time differences are located outside the stable range and show a tendency to decrease; determining the currently-set test transmission rate as the available bandwidth when the transmission delay time differences are within the stable range; and returning to the transmitting step after each of the setting steps.