| Summary: | 碩士 === 朝陽科技大學 === 網路與通訊研究所 === 94 === A mobile ad hoc network (MANET) is a dynamically reconfigurable wireless network that does not have a fixed infrastructure. Due to this kind of network is using wireless for communication. If we used the traditional transport protocol, the bandwidth will can not be utilized efficiently and it will cause some problems. Traditional transport protocol for wired network is not suitable for MANET. Because of the characteristics of MANET, the bandwidth is more limited than traditional network. It is therefore very important to utility the limited resource in MANET. In traditional TCP protocol, it faced many problems leaded to the bandwidth resource of MANETs will be not utilized.
In this thesis, we propose an improved transport protocol (ITP) and discussed the problems in transport layer over MANETs in order to solve such problems. The proposed scheme, called improved transport protocol, which includes two aspects. First we used a rate based transmission scheme with fuzzy logic control which is used to tune the proper data rate. This scheme is via layer cooperation in which the intermediate node uses its MAC layer collection information for adjustment. In another aspect, the traditional TCP protocol can not handle the problem which was caused by packet loss as the link failure. In ITP, we adopted an explicit link failure notification protocol (ELFN) which detect the link failure occur. Later ELFN will send the link failure notification to the source and find a new route early to prevent more packets loss. The ITP gets the MAC layer information and uses a fuzzy logic controller to estimate the appropriate data rate for transmission. Then, ITP used a feedback scheme to adjust the flow by receiving the feedback packet. The difference between traditional TCP and ITP is that the ITP adjusts its transmission rate by the received packet instead of the loss packets or acknowledgement.
Finally, simulation experiments showed that the proposed ITP outperforms ATP and the traditional TCP. These experiments analyzed the time of tuning approach to proper rate and the throughputs in different mobility.
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