Patent ID: 7593338

Claim:
A congestion control method in a communication system that transmits and receives a data segment using Transmission Control Protocol (TCP) and performs a Fast Retransmit mode and a Fast Recovery mode upon occurrence of a lost segment, comprising the steps of: retransmitting, by a transmission terminal, the lost segment to a reception terminal and then calculating the expected number of duplicate acknowledgements (ACKs) expected to be received from the reception terminal; determining by the transmission terminal whether an ACK currently received from the reception terminal is identical to a new ACK or a duplicate ACK; accumulating, by the transmission terminal, the received duplicate ACK, and comparing the number of the accumulated duplicate ACKs with the expected number of die duplicate ACKs; and retransmitting the lost segment to the reception terminal by the transmission terminal if the number of the accumulated duplicate ACKs is larger than the expected number of the duplicate ACKs, wherein the calculation step comprises the step of calculating the expected number of duplicate ACKs by subtracting a sequence number (seqno) of an ACK currently received by the transmission terminal from a maximum value maximum sequence (maxseq) among sequence numbers of segments transmitted up to the present to the reception terminal by the transmission terminal.