Browsing by Author "Ho, T. W."

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Improving the Channel Utilization of IEEE 802.11p/1609 Networks
(2009)
Wang, S. Y.
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Chou, C. L.
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Liu, K. C.
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Ho, T. W.
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Hung, W. J.
The IEEE 802.11p/1609 standards specify a suite of communication protocols for vehicular communication networks. A new operational mode, called the WAVE (Wireless Access in Vehicular Environments) mode, is defined to enable communication among high-speed vehicles or between a vehicle and a roadside infrastructure network. In the WAVE mode, a mobile/stationary station uses a combined FDMA/TDMA channel access scheme to switch its channel between the control channel and a service channel every 50 ms. The primary purpose of this design is to detect new services announced by other stations. However, if a station would like to use all of its service channel bandwidth to transmit a large volume of data to another station, switching back to the control channel every 50 ms without doing anything useful only unnecessarily reduces the maximum possible transmission throughput by a half. To overcome this problem, in this paper we propose an improved channel access scheme to allow a station to stay on a service channel as long as it requires before returning to the control channel. Our simulation results show that the proposed scheme significantly improves the service channel utilization under various network conditions.
NCTUns 4.0: An integrated simulation platform for vehicular traffic, communication, and network researches
(2007)
Wang, S. Y.
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Chou, C. L.
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Chin, Y. H.
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Tzeng, Y. S.
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Hsu, M. S.
In this paper, we present an integrated simulation platform, called NCTUns, for vehicular traffic, communication, and network researches. This platform combines the capabilities supported by a network simulator and those supported by a traffic simulator. With these simulation capabilities, NCTUns can be used to design protocols for Intelligent Transportation Systems (ITS) communication networks such as a wireless vehicular communication network. Besides, the novel architecture of the platform enables the real-world Linux protocol stack and any real-world application to be used in simulations of such networks. In this paper, we present the design of NCTUns for supporting ITS researches and show its scalability.