In wireless network, TCP Reno and TCP Vegas do not work well as they do in wired network, because they take packet losses or timeout as the signal of congestion. However, in wireless network, temporary link outages or fading-induced bit errors result in packet losses, so the TCP decreases the cwnd improperly. Some variations of TCP have been developed to improve the transport protocol performance for wireless network. These approaches progress along two directions. One direction is to hide any losses not related to congestion from the sender, so that the sender can only detect the packet losses due to congestion, such as I-TCP or snoopy protocol. However these protocols are not fit for ad hoc network in which there are no middle base stations between the wire link and the wireless link. Thus, the other direction, explicit congestion notification (ECN), is a promising direction in the wireless network. In the paper, we propose a new protocol based on expanded ECN mechanism to respond to packet losses in the wireless environment more properly. The paper gives the idea to construct the new mechanism, called TCP 3-states/ECN2, and analyses the stability of the new mechanism. By using the NS-2 simulator, the paper compares the new mechanism on throughput, drop ratio and delay time with TCP Reno and TCP Vegas. The simulation result indicates TCP 3-states/ECN2 mechanism can get better tradeoff of throughput and delay time, so it can work well in wireless environment