We present an active buffer control based TCP agent scheme that can overcome TCP performance degradation caused by handovers in broadband wireless networks. The agent performs an active buffer control and adjusts the sending rate of the TCP server by forcing three duplicate acknowledgements while it splits an end-to-end TCP connection into two TCP connections. So, high utilization is achievable even with frequent handovers. We also propose an active buffer control algorithm deployed in the agent and a guideline on design of the buffer control parameters using bandwidth-delay product. Simulation results reveal that high TCP throughput can be achieved in comparison with the Fast Retransmit scheme and the traditional TCP for the single traffic scenario without bottleneck, especially for the scenario with bottleneck in wired links. The proposed TCP agent scheme can be easily implemented with the traditional TCP without modifications at the end terminals.