In a packet communication system with large bandwidth delay product (BDP) and employing Transmission Control Protocol (TCP), the reported advertised window size as advertised by a receiver is employed only as an indication of window size and not as a throughput limit so that more data is sent than the amount specified by the advertised window size. Since the receiver can process all incoming TCP packets, the receiving buffer is consistently near empty. Since the TCP's advertised window size is not accepted as the absolute amount of buffer space available at the receiver, the sender is not constrained by the absolute value of the receiver's advertised window size and instead can transmit more data than the absolute value of the advertised window, enabling the system to increase the actual window size without modifying the link ends. This improved large-BDP-capable protocol is denoted TCP-SC.