Research Of Amelioration To TCP In Wireless Networks

TCP is an effective end-to-end transport protocol over fixed network. .However TCP's performance is decayed when it is used over wireless networks.This is mainly because that the error control mechanism is not serve thewireless networks. Standard TCP that designed for fixed network considers thatall losses are caused by congestion, this assumption for fixed network iscertainly true, but the factors caused losses over wireless networks are many,and not only congestion. For example, handoff, channel invalidation, high BERand temporary burst errors. So designing an effective error control mechanismis the key to improve TCP's performance over wireless networks.M-TCP proposed by K.Brown and S.Singh and TCP-Probing proposed byV.Tsaoussidis and H.Badr are respectively the representation of split connectionscheme and end-to-end scheme. The paper combines M-TCP and TCP-Probingprotocol, it is to say that adding probing mechanism to M-TCP protocol, and topropose a new mended protocol to TCP –EM-TCP to apply in wirelessnetworks. EM-TCP inherits M-TCP's ability to deal with packet losses causedby handoff, and EM-TCP can finds the good transmission state of wirelessnetworks in time after other errors caused packet losses occurred. This caneffectively increase the throughput of the protocol in wireless networks.The transmission performance of M-TCP,TCP-Probing and EM-TCP wasdetected by emulational experiment. The experiment proved that EM-TCP cansure increase the throughput in wireless networks, but EM-TCP should pay outsome overheads to obtain the increase of throughput.