| Summary: | 碩士 === 國立成功大學 === 資訊工程學系碩博士班 === 101 === To have reliable transmission in the VANET environment, a Split Reliable Transport Protocol (SRTP) is proposed in this thesis. The basic idea of SRTP is to separate a long connection into several sub-connections in order to reduce the overhead of packet retransmission, in which the length of each sub-connection depends on links’ states between vehicles. Three main issues that need to be resolved for SRTP are (1) how to decide the length of each sub-connection when a connection is established initially, (2) how to enhance the connection’s stability after the connection is established to deal with the fast topology change in the VANET environment, and (3) how to deal with packet congestion. An estimative scheme using location and speed information of vehicles to estimate the connectivity time of the links between vehicles are used in SRTP. The estimated values can be used to decide the lengths of sub-connections and adjust them dynamically. Another mechanism named Channel Busy Rate Aware (CBRA) congestion avoidance is proposed to avoid network congestion in the ad hoc network environment. In CBRA, busy rate and utility rate of the wireless channel for every node are used to adjust the source’s transmission rate and to avoid congestion. The simulation results show that SRTP can be operated well in the VANET environment and the aforementioned three issues can be appropriately resolved.
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