Multilayered optical OFDM for high spectral efficiency in visible light communication system

Photonic Network Communications - This paper presents two new schemes for improving the spectral efficiency of an optical orthogonal frequency-division multiplexing-based visible light...     

Energy Efficiency Improvements in Heterogeneous Network Through Traffic Load Balancing and Sleep Mode Mechanisms

Heterogeneous network (HetNet) is one of the most promising approaches of IMT Advanced, which not only offers higher capacity and data rate, but also network Energy Efficiency (EE). HetNet is an advanced network that promotes complex cooperation between multiple tiers or sizes of base stations, i.e. macro, micro, pico, and femto base stations towards the above benefits. In this paper, a theoretical model for evaluating the EE of HetNet is proposed. Then, a sleep mode mechanism on picocells is proposed to reduce the total energy consumption which subsequently improves the EE. Simulation results show that EE can be increased by balancing the traffic load between different types of base stations. In fact, the improvement very much depends on the percentage of traffic that is offloaded to picocells. At low to medium traffic load conditions, significant improvements in EE can be observed through the proposed sleep mechanism. It is observed that by combining the sleep mode feature of picocells and load balancing between the different types of base stations in HetNet, further EE improvements up to 68 % for low traffic load and up to 33 % for medium traffic load can be achieved.     

Teachers’ attitudes toward information and communication technologies: the case of Syrian EFL teachers

Based on the new technology initiative in Syrian education, this study explored the attitudes of high school English as a Foreign Language (EFL) teachers in Syria toward ICT. In addition, the study investigated the relationship between computer attitudes and five independent variables: computer attributes, cultural perceptions, computer competence, computer access, and personal characteristics (including computer training background). The findings suggest that teachers have positive attitudes toward ICT in education. Teachers’ attitudes were predicted by computer attributes, cultural perceptions and computer competence. The results point to the importance of teachers’ vision of technology itself, their experiences with it, and the cultural conditions that surround its introduction into schools in shaping their attitudes toward technology and its subsequent diffusion in their educational practice.