Browsing by Author "Hsieh, Tien-Yuan"

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A Novel Traffic Light Management Mechanism on Intersection
(2013)
Hsieh, Tien-Yuan
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Tsai, Pei-Chuan
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資訊工程學系
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Department of Computer Science
Currently, most traffic lights at street intersections operate according to a fixed setting. However in reality, vehicle flow rates of each direction are not always equivalent. As a result, the traffic light at the vertical roadway may turn red when no car is driving on the horizontal roadway, or remain in red when all cars on the horizontal roadway have passed the intersection. In this paper, we develop a novel traffic light management to relieve these situations. Besides, at cooperative vehicular safety environment of WAVE/DSRC, each vehicle installs an OBU that periodically broadcasts its current moving status. In addition, our proposed adaptive traffic light management mechanism will collect and analyze the information broadcasted by all OBUs. Hence, the traffic lights are able to dynamic adjust according the current vehicle flow rates of each direction and further reduce the red light waiting time and increase the traffic throughput at the street intersection.
A Probability Based MAC Channel Congestion Control Mechanism for VANET
(2013-01-01)
Hsu, Mark Chih-Wei
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Hsieh, Tien-Yuan
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資訊工程學系
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Department of Computer Science
A significant issue in VANETs (Vehicular Ad Hoc Networks) is the design of an effective MAC (Medium Access Control) or broadcast scheme which can facilitate the fast and reliable dissemination of critical safety messages to neighboring vehicles in case of an unexpected event. Broadcasting of data and control packets is expected to be crucial in vehicular environment. Most of the broadcasting packet is designed to be delivered on a given frequency during the control channel (CCH) interval set by the IEEE 1609.4 standard [1] (which provides enhancements to the IEEE 802.11p MAC by supporting multi-channel operation). In this paper, the probability based MAC channel congestion control mechanism is developed to cope with rapid topology changes, i.e., vehicles entering and leaving the network, as well as overloaded situations in terms of increased number of vehicles and/or increased amount of data traffic injected without collapsing. Method is also based on the estimation of potential neighboring vehicles through broadcasting Hello messages, and then based on probability model to calculate the expected offset slots for reduce the collision situations, and thus improve transmission performance.
Cooperative Vehicular Information Collection Based on the Cell-Weighted Policy
(2012-01-01)
Hsieh, Tien-Yuan
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Hsu, Chih-Wei
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資訊工程學系
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Department of Computer Science
Vehicular safety application is a critical ITS service in traffic management. In cooperative vehicular safety application, each vehicle must periodically broadcast its current speed, position, heading and identity to the surrounding vehicles. Because of lacking the channel utilization mechanism, inaccuracy of positioning and inconsistency of geographic information, cooperative vehicular safety application suffers many difficulties and limitations. In this paper, we identify out these problems and propose one RSU assisted on-demand vehicular information collection method, which is based on the geographic cell-weighted policy. Finally we show our demonstration and make conclusion.
V2PSense: Enabling Cellular-based V2P Collision Warning Service Through Mobile Sensing
(2018-01-01)
Li, Chi-Yu
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Salinas, Giovanni
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Huang, Po-Hao
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Tu, Guan-Hua
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Hsu, Guo-Huang
The C-V2X (Cellular Vehicle-to-Everything) technology is developing in full swing. One of its mainstream services can be the Vehicle-to-Pedestrian (V2P) service. It can protect pedestrians who are mostly vulnerable on the road. In this work, we seek to enable a V2P service that can identify which pedestrians may be nearby a dangerous driving event and then notify them of warning messages. To enable this V2P service, there are two major challenges. First, a low-latency V2P message transport is required for this infrastructure-based service. Second, the pedestrian's smartphone requires an energy-efficient outdoor positioning method instead of power-hungry GPS due to its limited battery life. We thus propose a novel solution, V2PSense, which trades off positioning precision for energy savings while achieving low-latency message transport with LTE high-priority bearers. It does a coarse-grained positioning by leveraging intermittent GPS information and mobile sensing data, which includes step count from the pedometer and cellular signal strength changes. Though the V2PSense's positioning is not as precise as the GPS, it can still ensure that all the pedestrians nearby dangerous spots can be notified. Our results show that it can achieve the average precision ratio 92.6% for estimating where the pedestrian is while saving 20.8% energy, compared with the GPS always-on case.