scholarly journals Adaptive Content Precaching Scheme Based on the Predictive Speed of Vehicles in Content-Centric Vehicular Networks

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5376
Author(s):  
Youngju Nam ◽  
Hyunseok Choi ◽  
Yongje Shin ◽  
Euisin Lee ◽  
Eun-Kyu Lee
Keyword(s):  
Vehicular Networks ◽  
Current Speed ◽  
Constant Speed ◽  
Multimedia Data ◽  
Average Speed ◽  
Large Size ◽  
Adaptive Value ◽  
Roadside Unit ◽  
Simulation Results ◽  
Adaptive Content

Content-Centric Vehicular Networks (CCVNs) are considered as an attractive technology to efficiently distribute and share contents among vehicles in vehicular environments. Due to the large size of contents such as multimedia data, it might be difficult for a vehicle to download the whole of a content within the coverage of its current RoadSide Unit (RSU). To address this issue, many studies exploit mobility-based content precaching in the next RSU on the trajectory of the vehicle. To calculate the amount of the content precaching, they use a constant speed such as the current speed of the vehicle requesting the content or the average speed of vehicles in the next RSU. However, since they do not appropriately reflect the practical speed of the vehicle in the next RSU, they could incorrectly calculate the amount of the content precaching. Therefore, we propose an adaptive content precaching scheme (ACPS) that correctly estimates the predictive speed of a requester vehicle to reflect its practical speed and calculates the amount of the content precaching using its predictive speed. ACPS adjusts the predictive speed to the average speed starting from the current speed with the optimized adaptive value. To compensate for a subtle error between the predictive and the practical speeds, ACPS appropriately adds a guardband area to the precaching amount. Simulation results verify that ACPS achieves better performance than previous schemes with the current or the average speeds in terms of the content download delay and the backhaul traffic overhead.

scholarly journals On the Design of Efficient Hierarchic Architecture for Software Defined Vehicular Networks

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1400
Author(s):  
Muhammad Adnan ◽  
Jawaid Iqbal ◽  
Abdul Waheed ◽  
Noor Ul Amin ◽  
Mahdi Zareei ◽  
...  
Keyword(s):  
Cloud Computing ◽  
Quality Of Service ◽  
Traffic Management ◽  
Vehicular Networks ◽  
Scheduling Algorithm ◽  
Main Research ◽  
First Come First Serve ◽  
Computing Framework ◽  
Simulation Results

Modern vehicles are equipped with various sensors, onboard units, and devices such as Application Unit (AU) that support routing and communication. In VANETs, traffic management and Quality of Service (QoS) are the main research dimensions to be considered while designing VANETs architectures. To cope with the issues of QoS faced by the VANETs, we design an efficient SDN-based architecture where we focus on the QoS of VANETs. In this paper, QoS is achieved by a priority-based scheduling algorithm in which we prioritize traffic flow messages in the safety queue and non-safety queue. In the safety queue, the messages are prioritized based on deadline and size using the New Deadline and Size of data method (NDS) with constrained location and deadline. In contrast, the non-safety queue is prioritized based on First Come First Serve (FCFS) method. For the simulation of our proposed scheduling algorithm, we use a well-known cloud computing framework CloudSim toolkit. The simulation results of safety messages show better performance than non-safety messages in terms of execution time.

Research on Speed Observer of PMSM Servo System

2011 ◽  
Vol 317-319 ◽  
pp. 1223-1227
Author(s):  
Rui Ning Huang ◽  
Cheng Song ◽  
Xiao Hui Liu ◽  
Yun Jiang Lou
Keyword(s):  
Kalman Filter ◽  
Control System ◽  
Servo System ◽  
Detection Accuracy ◽  
Optical Encoder ◽  
Average Speed ◽  
Speed Range ◽  
Simulation Results ◽  
Instantaneous Speed ◽  
Speed Simulation

The incremental optical encoder is widely used in PMSM servo system for speed detection. However, this method is detected the average speed, which will cause delay time, and make the speed control system unstable at low speed range. A speed observer was designed in this paper, which is combining state observer and Kalman filter to estimate instantaneous speed. Simulation results show that this method can improve the speed detection accuracy of the PMSM servo system.

A Roadside Unit-Based Localization Scheme to Improve Positioning for Vehicular Networks

2016 ◽  
Author(s):  
Frances A. Santos ◽  
Ademar T. Akabane ◽  
Roberto S. Yokoyama ◽  
Antonio A. F. Loureiro ◽  
Leandro A. Villas
Keyword(s):  
Vehicular Networks ◽  
Localization Scheme ◽  
Roadside Unit

A Piezoelectrically Actuated Scaning Micromirror Integrated with Angle Sensors

2011 ◽  
Vol 483 ◽  
pp. 437-442 ◽  
Author(s):  
Rong Rong Qian ◽  
Zhi Yu Wen ◽  
Li Chen
Keyword(s):  
Large Deflection ◽  
Deflection Angle ◽  
Maximum Output ◽  
Angle Sensor ◽  
Torsional Mode ◽  
Optical Scanning ◽  
Large Size ◽  
Simulation Results ◽  
Piezoelectric Cantilevers ◽  
Scanning Systems

A novel piezoelectrically actuated scanning micromirror integrated with angle sensors is presented. The mirror with large size of 3×3mm2 locates in the center of the device, and piezoelectric actuators are symmetrically placed on both sides of the mirror. They are connected through torsion bars in which piezoelectric angle sensors are integrated. In order to obtain large deflection angle at a low operation voltage, the new actuator consisting of several parallel piezoelectric cantilevers is adopted. The machematical models of the mirror and piezoelectric actuator are given, and the piezoelectric angle sensors are designed to obtain high sensitivities. The simulation results indicate that the maximum mechanical deflection angle of the micromirror is 12.4° at an operation voltage of 25V, and the maximum output voltage of the angle sensor is 164.3mV. The resonant frequency associated with the torsional mode is 960Hz. The sensitivity of the angle sensor is 13.3mV/° without amplifying. The Scanning miromirror is suitable for optical scanning systems such as the microscope, the micro-spectrometer, the medical imaging, the barcode reader and so on.

scholarly journals A Delay and Energy Efficient Multicast Routing Protocol using IWO and MOLO Algorithm for Vehicular Networks

2019 ◽  
Vol 8 (12) ◽  
pp. 3048-3055
Keyword(s):  
Energy Consumption ◽  
Energy Efficient ◽  
Vehicular Networks ◽  
Intelligent Transportation System ◽  
Multicast Routing ◽  
Learning Algorithm ◽  
Network Simulator ◽  
Wireless Communication Network ◽  
Multicast Routing Protocol ◽  
Simulation Results

Vehicular networks are significantly improving wireless communication network which provides an intelligent transportation system services among faster moving vehicles with internet and brings safety and comfort drive. From a single source vehicle the multicast routing protocols delivers multicast messages to all members of the multicast group by means of multi-hop communication. Increasing the density of vehicles results in channel overload, which increases the probability of data collision; hence reduction in successful received data will increase the delay. Therefore, delay and energy consumption are the major constraints that should affect the performance of routing. In this paper we suggest a delay and energy efficient multicast routing (DEMR) protocol for vehicular network using a hybrid machine learning algorithm. The DEMR protocol consists of four layers; are vehicle layer, fog layer, OpenFlow switch layer, and SDN controller layer. Moreover, to partition the vehicle layer, and select the optimal multicast path based on multiple constraints improved weed optimization (IWO) algorithm is proposed. IWO algorithm separates the multicast request into emergency, common and police requests. We design a multi-objective lion optimization (MOLO) algorithm among fog nodes for resource management, which increases the utilization of resources in fog layer and decrease the response time of multicast session request. MOLO algorithm removes the unnecessary flow table and session table entries in the controller. The DEMR protocol is implemented in Network Simulator (NS3) tool and simulation results are compared with the protocols as EEMSFV, MABC, and CVLMS. From the simulation results we conclude that the DEMR algorithm is better than EEMSFV, MABC and CVLMS in terms of transmission ratio, overhead load, average end to end delay, packet loss ratio and, energy consumption.

scholarly journals Cooperation as a Service in VANET: Implementation and Simulation Results

2012 ◽  
Vol 8 (2) ◽  
pp. 153-172 ◽  
Author(s):  
Hajar Mousannif ◽  
Ismail Khalil ◽  
Stephan Olariu
Keyword(s):  
Ad Hoc Networks ◽  
Traffic Safety ◽  
Vehicular Networks ◽  
Vehicular Ad Hoc Networks ◽  
Ad Hoc ◽  
Network Routing ◽  
The Road ◽  
Vehicle To Vehicle ◽  
Simulation Results ◽  
Hoc Networks

The past decade has witnessed the emergence of Vehicular Ad-hoc Networks (VANET), specializing from the well-known Mobile Ad Hoc Networks (MANET) to Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) wireless communications. While the original motivation for Vehicular Networks was to promote traffic safety, recently it has become increasingly obvious that Vehicular Networks open new vistas for Internet access, providing weather or road condition, parking availability, distributed gaming, and advertisement. In previous papers [27,28], we introduced Cooperation as a Service (CaaS); a new service-oriented solution which enables improved and new services for the road users and an optimized use of the road network through vehicle's cooperation and vehicle-to-vehicle communications. The current paper is an extension of the first ones; it describes an improved version of CaaS and provides its full implementation details and simulation results. CaaS structures the network into clusters, and uses Content Based Routing (CBR) for intra-cluster communications and DTN (Delay–and disruption-Tolerant Network) routing for inter-cluster communications. To show the feasibility of our approach, we implemented and tested CaaS using Opnet modeler software package. Simulation results prove the correctness of our protocol and indicate that CaaS achieves higher performance as compared to an Epidemic approach.

scholarly journals A Privacy-Preserving Traffic Monitoring Scheme via Vehicular Crowdsourcing

Sensors ◽  
2019 ◽  
Vol 19 (6) ◽  
pp. 1274 ◽  
Author(s):  
Chuan Zhang ◽  
Liehuang Zhu ◽  
Chang Xu ◽  
Xiaojiang Du ◽  
Mohsen Guizani
Keyword(s):  
Traffic Congestion ◽  
Road Safety ◽  
Security Analysis ◽  
Traffic Monitoring ◽  
Privacy Preserving ◽  
Average Speed ◽  
Traffic Conditions ◽  
Roadside Unit ◽  
Paillier Cryptosystem ◽  
Effectiveness And Efficiency

The explosive number of vehicles has given rise to a series of traffic problems, such as traffic congestion, road safety, and fuel waste. Collecting vehicles’ speed information is an effective way to monitor the traffic conditions and avoid vehicles’ congestion, however it may threaten vehicles’ location and trajectory privacy. Motivated by the fact that traffic monitoring does not need to know each individual vehicle’s speed and the average speed would be sufficient, we propose a privacy-preserving traffic monitoring (PPTM) scheme to aggregate vehicles’ speeds at different locations. In PPTM, the roadside unit (RSU) collects vehicles’ speed information at multiple road segments, and further cooperates with a service provider to calculate the average speed information for every road segment. To preserve vehicles’ privacy, both homomorphic Paillier cryptosystem and super-increasing sequence are adopted. A comprehensive security analysis indicates that the proposed PPTM can preserve vehicles’ identities, speeds, locations, and trajectories privacy from being disclosed. In addition, extensive simulations are conducted to validate the effectiveness and efficiency of the proposed PPTM scheme.

Sign in / Sign up

Export Citation Format

Share Document