Feedback information including a transmission quality of a packet transmitted from a transmitting device to a receiving device is received from the receiving device and the transmission quality included in the feedback information is revised down, to be transferred to the transmitting device, based on information of resource consumed for maintaining a wireless link included in a path to the receiving device. The above revising down is executed if it is found that the information of resource consumed reaches a predetermined threshold or is not executed unless it is found otherwise. The information of resource includes, for example, the number of retransmission times of a packet for a predetermined period of time, a transmission power level or a code length of an error correcting code.