Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí hóa hoc quốc tế đề tài : Clustering and OFDMA-based MAC protocol (COMAC) for vehicular ad hoc networks | Abdel Hafeez et al. EURASIP Journal on Wireless Communications and Networking 2011 2011 117 EURASIP Journal on http content 20ll l l 17 Wireless Communications and Networking a SpringerOpen Journal RESEARCH Open Access Clustering and OFDMA-based MAC protocol COMAC for vehicular ad hoc networks Khalid Abdel Hafeez Lian Zhao Zaiyi Liao and Bobby Ngok-Wah Ma Abstract The IEEE community is working on the wireless access in vehicular environments as a main technology for vehicular ad hoc networks. The medium access control MAC protocol of this system known as IEEE is based on the distributed coordination function DCF of the IEEE and enhanced DCF of the IEEE that have low performance especially in high-density networks with nodes of high mobility. In this paper we propose a novel MAC protocol where nodes dynamically organize themselves into clusters. Cluster heads are elected based on their stability on the road with minimal overhead since all clustering information is embedded in control channel s safety messages. The proposed MAC protocol is adaptable to drivers behavior on the road and has learning mechanism for predicting the future speed and position of all cluster members using the fuzzy logic inference system. By using OFDMA each cluster will use a set of subcarriers that are different from the neighboring clusters to eliminate the hidden terminal problem. Increasing the system reliability reducing the time delay for vehicular safety applications and efficiently clustering vehicles in highly dynamic and dense networks in a distributed manner are the main contributions of our proposed MAC protocol. Keywords vehicular ad hoc network VANET medium access control clustering mobility reliability fuzzy logic 1. Introduction The increase in number of vehicles on our roads and the immense number of fatal accidents they cause have driven the research and development of new-generation technologies that help drivers travel more
