In one illustrative example, a method in a wireless router system for transmitting data packets to a mobile communication device through the wireless communication network based upon a round trip time associated with communication of each data packet is provided. The round trip time is a time period between the transmission of each data packet and reception of a corresponding acknowledgement signal from the mobile communication device. A number of data packets matched for a window size are transmitted to the mobile communication device, and a round trip time associated with communication of each of the transmitted data packets is measured. The window size for data packet transmission is re-sized by increasing the window size if the round trip time associated with the communication of each of the transmitted data packets is within a first time threshold, and decreasing the window size if the round trip time associated with the communication of any of the transmitted data packets is more than the first time threshold but less than a second time threshold. The window size is also decreased if the round trip time of any of the transmitted data packets is more than the second time threshold, where each such data packet is further marked as a lost data packet. A number of data packets matched for the re-sized window is subsequently transmitted, including a retransmission any data packets marked as lost. The steps of the method are repeated from the measuring step until data packets to be transmitted are exhausted.