Browsing by Author "He, Ting-Wei"

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A vehicle collision warning system employing vehicle-to-infrastructure communications
(2008)
Wang, Shie-Yuan
;
Cheng, Yow-Wei
;
Lin, Chih-Che
;
Hong, Wei-Jyun
;
He, Ting-Wei
Road safety has become an important issue and gained much attention for many years. To avoid vehicle collisions on the roads, researchers have proposed various collision warning systems (CWS) using different technologies. Compared with CWS using other technologies, a radio based CWS is more capable of avoiding collisions in off sight scenarios (such as the four corners of an intersection). Most existing radio based CWSs operate using vehicle to vehicle communications. However, in such CWSs, high mobility of moving vehicles easily results in message collisions and link breakage, impairing the reliability of these CWSs. An alternative is employing vehicle to infrastructure communication to build CWSs. In this paper, we propose a radio based CWS employing vehicle to infrastructure communications. Our simulation results show that the proposed CWS can effectively reduce the number of vehicle collisions without degrading the traffic throughput of a road network.
Evaluating and Improving the TCP/UDP Performances of IEEE 802.11(p)/1609 Networks
(2008)
Wang, Shie-Yuan
;
Chao, Hsi-Lu
;
Liu, Kuang-Che
;
He, Ting-Wei
;
Lin, Chih-Che
The IEEE 802.11(p)/1609 standard is an emerging technology for vehicular communication networks. It amends the IEEE 802.11-2007 standard and defines a new WAVE operational mode for vehicular environments. The WAVE mode utilizes a combined FDMA/TDMA scheme to manage network bandwidth. In this mode, a node must periodically switch its frequency channel between two different channels over time. Such a design may result in bandwidth wastage due to the residual time caused by channel switching. In this paper, we propose two easy-to-implement schemes to mitigate this problem and compare their TCP/UDP performances with those of the original scheme. Our simulation results provide many insights into the operations of these schemes on IEEE 802.11(p)/1609 networks and show that the proposed schemes always outperform the original scheme.