Research On TCP Perfprmance In Wireless Network

As the development of wireless communication technologies and users' requirements, the future mobile communication network should be a mixed network which is based on IP and composed of fixed and wireless network. There are many problems if traditional TCP is used directly in such mixed network, which is mainly because of the features of wireless links and TCP's model supposition of lost packages.So how to enhance the performance of TCP under wireless network has been the hotspot of researches. There are three main kinds of ways on the TCP performance's enhancement: link layer ways, splitting connection ways and end-to-end ways.3GPP Long Term Evolution (LTE) is the largest research project on new techniques initiated by 3GPP. This LTE technique bases on OFDM/FDMA and it is a revolution in communication industry. But so far, there have been few researches on the TCP performances in LTE network.To study the problems mentioned above, this paper firstly introduces the contents of LTE and wireless TCP, then sets up the LTE system-level network-layer emulators, and mostly models the TCP congestion mechanism, and finally it obtains the performance of basic TCP. As the reasons mentioned above, the results of TCP and LTE network performance are both bad.To improve the performances of TCP and LTE system, this paper give a new cross-layer TCP method. This method combines the end-to-end wireless TCP on transport layer, HARQ on MAC layer and ARQ on RLC layer, and it can greatly enhance TCP and LTE system's performance. The simulation results reveal that using this cross-layer TCP method, the spectrum efficiency of LTE system can achieve 1.49bit/s/Hz, which can reach the LTE demand.