The systems in which information and communication technologies and systems engineering concepts are utilized to develop and improve transportation systems of all kinds are called “The Intelligent Transportation Systems (ITS)”. ITS integrates information, communications, computers and other technologies and uses them in the field of transportation to build an integrated system of people, roads and vehicles by utilizing advanced data communication technologies. Vehicular Ad-hoc Networks which is a subset of Mobile Ad-hoc Networks, provide Vehicle to Vehicle (V2V), Vehicle to Roadside (V2R) and Vehicle to Infrastructure (V2I) communications and plays an important role in Intelligent Transportation System. Due to special characteristics of VANETs, QoS (Quality of Service) provisioning in these networks is a challenging task. QoS is the capability of a network for providing superior service to a selected network traffic over various heterogeneous technologies. In this paper we present an overview of Vehicular Networks, QoS Concepts, QoS challenges in VANETs and approaches which aim to enhance the Quality of Service in Vehicular Networks تفاصيل المقالة

In this paper, a hierarchical routing approach based on network clustering and using mobile sinks is proposed in WSN. The first, second, and third levels of hierarchy are composed of sensors, cluster heads (CHs) and mobile sinks (gateways), respectively. The most important challenges in the second level of hierarchy are: 1) election of the most suitable node as CH, and 2) reduction of communication overhead of CH election algorithm. Mobile gateway uses different data transfer technologies (e.g. SMS, WiFi, and 3G) and each communication technology has different characteristics in terms of cost, energy consumption pattern, etc. However, the characteristics of available mobile gateway(s) are ignored in designing CH election algorithm in previous studies. Designing CH election algorithm without considering the characteristics of gateways may lead to problems such as increasing data transfer costs and network fragmentation. Thus, unlike previous studies, a new fitness function is designed with respect to local fitness value of a sensor and fitness value of its available mobile sink(s). In addition, an auction-based method is adopted to control communication overhead of CH election algorithm. The performance of the proposed approach in name DACMS is evaluated in OPNET 14.5 simulation platform. The simulation results show that DACMS outperforms MECA. تفاصيل المقالة