The problem of high BER (bit error rate) usually plagues the wireless communication, especially for the TCP connections. As TCP cannot distinguish wireless loss from congestion loss, thus its performance over high BER wireless networks suffers from unnecessary congestion window decreases. To improve the performance of TCP in such a scenario, a Dynamic-Segment method for MAC 802.11 (DS-MAC) is proposed. Simulation experiments show that the proposed method is fair, and can result in higher TCP throughput along with higher bandwidth utilization efficiency.