Green Cellular Networks: A Survey, Some Research Issues and Challenges

Energy efficiency in cellular networks is a growing concern for cellular operators to not only maintain profitability, but also to reduce the overall environment effects. This emerging trend of achieving energy efficiency in cellular networks is motivating the standardization authorities and network operators to continuously explore future technologies in order to bring improvements in the entire network infrastructure. In this article, we present a brief survey of methods to improve the power efficiency of cellular networks, explore some research issues and challenges and suggest some techniques to enable an energy efficient or "green" cellular network. Since base stations consume a maximum portion of the total energy used in a cellular system, we will first provide a comprehensive survey on techniques to obtain energy savings in base stations. Next, we discuss how heterogeneous network deployment based on micro, pico and femto-cells can be used to achieve this goal. Since cognitive radio and cooperative relaying are undisputed future technologies in this regard, we propose a research vision to make these technologies more energy efficient. Lastly, we explore some broader perspectives in realizing a "green" cellular network technologyComment: 16 pages, 5 figures, 2 table

A Review and Synthesis of the Outcomes from Low Carbon Networks Fund Projects

The Low Carbon Networks Fund (LCNF) was established by Ofgem in 2009 with an objective to “help Distribution Network Operators (DNOs) understand how they provide security of supply at value for money and facilitate transition to the low carbon economy”. The £500m fund operated in a tiered format, funding small scale projects as Tier 1 and running a Tier 2 annual competitive process to fund a smaller number of large projects. By 31st March 2015, forty Tier 1 projects and twenty-three Tier 2 projects had been approved with project budgets totalling £29.5m and £220.3m respectively. The LCNF governance arrangements state that projects should focus on the trialling of: new equipment (more specifically, that unproven in GB), novel arrangements or applications of existing equipment, novel operational practices, or novel commercial arrangements. The requirement that learning gained from projects could be disseminated was a key feature of the LCNF. The motivation for the review reported here was a recognition that significant learning and data had been generated from a large volume of project activity but, with so many individual reports published, that it was difficult for outside observers to identify clear messages with respect to the innovations investigated under the programme. This review is therefore intended to identify, categorise and synthesise the learning outcomes published by LCNF projects up to December 2015

Active Management of Distributed Generation based on Component Thermal Properties

Power flows within distribution networks are expected to become increasingly congested with the proliferation of distributed generation (DG) from renewable energy resources. Consequently, the size, energy penetration and ultimately the revenue stream of DG schemes may be limited in the future. This research seeks to facilitate increased renewable energy penetrations by utilising power system component thermal properties together with DG power output control techniques. The real-time thermal rating of existing power system components has the potential to unlock latent power transfer capacities. When integrated with a DG power output control system, greater installed capacities of DG may be accommodated within the distribution network. Moreover, the secure operation of the network is maintained through the constraint of DG power outputs to manage network power flows. The research presented in this thesis forms part of a UK government funded project which aims to develop and deploy an on-line power output control system for wind-based DG schemes. This is based on the concept that high power flows resulting from wind generation at high wind speeds could be accommodated since the same wind speed has a positive effect on component cooling mechanisms. The control system compares component real-time thermal ratings with network power flows and produces set points that are fed back to the DG for implementation. The control algorithm comprises: (i) An inference engine (using rule-based artificial intelligence) that decides when DG control actions are required; (ii) a DG set point calculator (utilising predetermined power flow sensitivity factors) that computes updated DG power outputs to manage distribution network power flows; and (iii) an on-line simulation tool that validates the control actions before dispatch. A section of the UK power system has been selected by ScottishPower EnergyNetworks to form the basis of field trials. Electrical and thermal datasets from the field are used in open loop to validate the algorithms developed. The loop is then closed through simulation to automate DG output control for increased renewable energy penetrations

Civil Engineer Company Grade Officer Training Needs Analysis for Contingency Operations

In terms of active duty personnel, the USAF is the smallest it has ever been since its creation in 1947. With fewer personnel to accomplish essential tasks, the training of Airmen is more important than ever. Outdated and irrelevant training can lead to gaps in the knowledge of trainees. The purpose of this research was to analyze the training needs of Civil Engineer (CE) Company Grade Officers (CGOs) in the contingency environment. This was done by first conducting a Job Analysis (JA). The JA resulted in a list of 36 critical tasks and 58 important Knowledge, Skills, and Abilities (KSAs). The tasks rated most critical were those associated with presenting information to superiors, project management, construction management, and operations and maintenance. The most important KSAs included the ability to work in teams, critical thinking, time and stress management, and leadership. These results were used to create a test instrument to assess contingency job knowledge in a sample of 64 CE CGOs. The lowest scoring areas of the test included Prime BEEF concepts, joint forces, enlisted CE AFSC knowledge, contingency construction standards, general construction activities, reach-back resources, deployed leadership, project scheduling, BOS-I and SAA, contingency base types, contract types, and construction inspection. The knowledge gaps represented the training needs for CE CGOs in the contingency environment. The career field should consider the findings of this research when making decisions regarding the content of future contingency training curriculums for CE CGOs

Power consumption evaluation of circuit-switched versus packet-switched optical backbone networks

While telecommunication networks have historically been dominated by a circuit-switched paradigm, the last decades have seen a clear trend towards packet-switched networks. In this paper we evaluate how both paradigms perform in optical backbone networks from a power consumption point of view, and whether the general agreement of circuit switching being more power-efficient holds. We consider artificially generated topologies of various sizes, mesh degrees and not yet previously explored in this context transport linerates. We cross-validate our findings with a number of realistic topologies. Our results show that, as a generalization, packet switching can become preferable when the traffic demands are lower than half the transport linerate. We find that an increase in the network node count does not consistently increase the energy savings of circuit switching over packet switching, but is heavily influenced by the mesh degree and (to a minor extent) by the average link length

The history of WiMAX: a complete survey of the evolution in certification and standarization for IEEE 802.16 and WiMAX

Most researchers are familiar with the technical features of WiMAX technology but the evolution that WiMAX went through, in terms of standardization and certification, is missing and unknown to most people. Knowledge of this historical process would however aid to understand how WiMAX has become the widespread technology that it is today. Furthermore, it would give insight in the steps to undertake for anyone aiming at introducing a new wireless technology on a worldwide scale. Therefore, this article presents a survey on all relevant activities that took place within three important organizations: the 802.16 Working Group of the IEEE (Institute of Electrical and Electronics Engineers) for technology development and standardization, the WiMAX Forum for product certification and the ITU (International Telecommunication Union) for international recognition. An elaborated and comprehensive overview of all those activities is given, which reveals the importance of the willingness to innovate and to continuously incorporate new ideas in the IEEE standardization process and the importance of the WiMAX Forum certification label granting process to ensure interoperability. We also emphasize the steps that were taken in cooperating with the ITU to improve the international esteem of the technology. Finally, a WiMAX trend analysis is made. We showed how industry interest has fluctuated over time and quantified the evolution in WiMAX product certification and deployments. It is shown that most interest went to the 2.5 GHz and 3.5GHz frequencies, that most deployments are in geographic regions with a lot of developing countries and that the highest people coverage is achieved in Asia Pacific. This elaborated description of all standardization and certification activities, from the very start up to now, will make the reader comprehend how past and future steps are taken in the development process of new WiMAX features

BCBU + handbook : a guide to establish virtual cross-border campus for BCBU network

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Design, development and evaluation of the ruggedized edge computing node (RECON)

The increased quality and quantity of sensors provide an ever-increasing capability to collect large quantities of high-quality data in the field. Research devoted to translating that data is progressing rapidly; however, translating field data into usable information can require high performance computing capabilities. While high performance computing (HPC) resources are available in centralized facilities, bandwidth, latency, security and other limitations inherent to edge location in field sensor applications may prevent HPC resources from being used in a timely fashion necessary for potential United States Army Corps of Engineers (USACE) field applications. To address these limitations, the design requirements for RECON are established and derived from a review of edge computing, in order to develop and evaluate a novel high-power, field-deployable HPC platform capable of operating in austere environments at the edge

PAPR In LTE UPLINK : Problem and Improvement

LTE-Advanced is one of the most competing and widely adopted families of standards that will meet the 4G broadband wireless mobile communications requirements recommended by the IMT-Advanced for the terrestrial radio interface specifications. Pre-commercial deployments have proved that LTE-Advanced will ensure the competitiveness of the 4G mobile networks by providing a high-data-rate , low latency and optimized system. Unlike the IEEE802.16m WiMAX which uses OFDMA in both downlink and uplink multiple access schemes, LTE and its advanced version systems continue to use different multiple access transmissions in which OFDMA and SC-FDMA are supported in the downlink and the uplink, respectively. The idea to use OFDMA in the LTE uplink communications invoked discord among the members of the 3GPP standardization body because of the growing concern over the signal peakiness which degrades the efficiency of mobile station power battery consumption. The dire consequence of the peak amplitudes generated by the superposition of several subcarriers of identical phases led 3GPP to adopt SC-FDMA as an uplink multiple access method. Thus in this paper , the effect of pulse shaping on the performance of the uplink PAPR of distributed FDMA and localized FDMA will be dealt deeply. The performance improvement will be done by varying the roll-off factor of the raised-cosine filter for pulse shaping after IFFT.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format