AN IMPROVED TCP CONGESTION CONTROL ALGORITHM OVER MIXED WIRED/WIRELESS NETWORKS

Research into the performance issues of TCP over wireless networks has been the focus of much attention in recent years. In this paper, based on TCP Reno, an improved TCP congestion control algorithm named TCP-RQB is proposed in mixed wired/wireless networks. To apply the algorithm into a TCP enhancement scheme, the ratio of the number of queuing packets to the buffer size in bottleneck link is estimated. And the algorithm uses the ratio as a parameter to determine congestion level, uses four sub-phases to improve TCP Reno congestion avoidance phase according to congestion level, so that the transmission can be more long-term stability at high-speed status. When packet loss, the algorithm distinguishes congestion loss from wireless loss according to congestion level, then adjusts the congestion window and slow start threshold. NS2-based simulation experiments show that the TCP-RQB algorithm is superior to the traditional TCP Reno protocol.