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Journal of Green EngineeringJournal divested in January 2019, new journal website is: www.jgenng.com

Editor-in-Chief: Michele Albano, ISEP - Instituto Superior de Engenharia do Porto, Portugal

ISSN: 1904-4720 (Print Version),

ISSN: 2245-4586 (Online Version)
Vol: 2   Issue: 1

Published In:   January 2012

Publication Frequency: Quarterly

Search Available Volume and Issue for Journal of Green EngineeringJournal divested in January 2019, new journal website is: www.jgenng.com

Journal Description        Read Full Articles        Editorial Board        Subscription        Indexed

Greening of Video Streaming to Mobile Devices by Pervasive Wireless CDN

Dragan Boscovic1, Faramak Vakil1, Staniša Dautović2 and Milenko Tošić3

1Motorola Mobility, 600 US Highway 45, Libertyville, IL 60048, USA;
2Faculty of Technical Sciences, UNS, Trg Dositeja Obradovica 6, 21000 Novi Sad, Serbia;
3La Citadelle Inzenjering, Narodnog Fronta 35, 21000 Novi Sad, Serbia;

Abstract: [+]    |    Download File [ 1947KB ]

Abstract: Content Delivery Networks (CDNs) play an important role in today's video distribution solutions. While the need for efficient content delivery is well understood, the energy consumption of various video CDN topologies deserves extra attention since energy considerations are increasingly becoming a key performance factor for system designers and operators. This paper investigates the energy efficiency aspect of a special class of video CDN system, namely pervasive wireless CDN based on wireless mesh network implementation. We start by analyzing and defining the energy efficiency of a generic video CDN system. Then we introduce mathematical analysis and simulation model description for wireless CDNs exploring the idea of content placement among wireless access points which serve as local video servers. Computer simulation analysis, based on mixed integer linear programming model, is used to derive "optimal" content placement and caching strategies while minimizing the energy consumption subject to a constraint in terms of the storage size at each mesh router. The objective function of the mathematical model captures the desire to optimize multiple performance factors. In this particular case we are focusing on the QoS/latency time and power consumption. The results demonstrate trade-off dependency between QoS and power consumption. In summary, the paper offers additional insight into the content diffusion strategies as related to a pervasive wireless CDN, and implications of the placement strategies relative to its energy efficiency.

Keywords: Wireless Mesh Network (WMN), energy efficiency, CDN, video streaming, caching, average delivery tree length

Energy Efficiency in Cognitive Radio Network

P.S.M. Tripathi and Ramjee Prasad

Centre for Teleinfrastructure (CTiF), Aalborg University, Aalborg, Denmark;

Abstract: [+]    |    Download File [ 304KB ]

Abstract: In recent years, green communications has received a lot of attention in academic society. Cognitive radio techniques have been introduced to improve the spectrum utilization in already allocated spectrum band to licensed user as well as it promotes green communications. Under spectrum sharing model, secondary users can share spectrum with primary users under condition that total interference caused by SUs should not be exceeded from a predefined level. Energy efficiency is one of the important metric in cognitive radio network as it has to work under strict transmit power constraint. In this paper we explore how better energy efficiency can be achieved in spectrum sharing environment. Our analysis shows that energy efficiency in cognitive radio network is better when number of secondary users is more than available channels.

Keywords: cognitive radio, quality of service, power control, spectrum sharing, energy efficiency

Green by ICT

Basavaraj Hooli

MphasiS Ltd., CC2, Magarapatta, Pune 411028, India;

Abstract: [+]    |    Download File [ 4127KB ]

Abstract: Information and Communication Technology (ICT) consumes energy. Though ICT is responsible for 2% of global carbon emission, it helps in conserving the energy. Conventionally, it has done so by optimizing the performance of energy-using systems and processes in industry and commerce. In the near future, ICT will play a critical role in supporting the necessary paradigm shifts in the human behaviour through better understanding of the ecological impact by the various industry sectors by providing the necessary data and the awareness. Through Life Cycle Assessment tools, ICT will help in optimizing the use of energy. Within the energy sector, ICT will help towards more sustainable electricity generation. With the advent of `smart' technology from the field of ubiquitous computing, further ways of reducing growing levels of domestic energy consumption are now emerging. As per some reports Applications of ICT could enable emissions reductions of 15% of business-as-usual emissions. ICT will be instrumental in helping to develop new, climate-friendly technologies that can help economy's growth sustain ably and reduce emissions in the years ahead. This paper is towards giving more understanding of the Life Cycle Assessment and how it could become a key factor in reducing the rate of climate change.

Keywords: life cycle assessment, energy management, energy convergence, ecological intelligence

Energy-Efficiency of Cooperative Sensing Schemes in Ad Hoc WLAN Cognitive Radios

Reshma Syeda and Vinod Namboodiri

Department of Electrical Engineering & Computer Science, Wichita State University, 1845 Fairmount St., Wichita, KS 67260, USA;

Abstract: [+]    |    Download File [ 2383KB ]

Abstract: In cognitive radio networks, the secondary users need to coordinate among themselves to reap the benefits of cooperative spectrum sensing. In this paper, we study and analyze the energy efficiency of two generic cooperative sensing schemes in an ad hoc WLAN backdrop – distributed cooperative sensing scheme and centralized cluster based cooperative sensing scheme. We further propose corresponding enhanced and adaptive versions of these two schemes where only an  fraction of nodes sense in each sensing cycle, as opposed to all the nodes in the network. Using an analytical energy model for sensing, we quantify the energy costs of each of these schemes and perform a comparative numerical analysis to demonstrate the amount of energy savings of the proposed cooperative schemes over their generic counterparts and non-cooperative schemes.

Keywords: cognitive radio, cooperative sensing, energy efficiency, WLAN

The Role of Wireless Sensor Networks for Green Gigabit Access Networks

V. Suraci

Department of Engineering, Università degli Studi e-Campus, Via Isimbardi 10, Novedrate (CO), 22060 Italy;

Abstract: [+]    |    Download File [ 805KB ]

Abstract: Actual home networks have become an heterogeneous environment in terms of technologies used and do not take into account any intelligent energy saving mechanism. In this paper we propose an energy saving strategy by integrating a Wireless Sensor Network (WSN) with a high speed, hybrid home network. The main objective is to demonstrate that a WSN can act as a dependable control plane, where low data rate control packets can flow even when the high speed home network is shut down. While the home network nodes or some of each node's network technologies can be deactivate, the WSN is always on and, due to the low data rate required to properly work, it consumes a very limited quantity of energy. This mutual interaction between the high speed home network and the WSN allows at the same time to achieve the convergence of heterogeneous communication technologies in the home environment and leads to a substantial reduction of the energy consumptions. Simulation results show that this strategy is effective in a multitude of scenarios and provides a tangible economic benefit.

Keywords: green, home network, gigabit access, future internet

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