The Experts below are selected from a list of 15279 Experts worldwide ranked by ideXlab platform
Jie Zhang - One of the best experts on this subject based on the ideXlab platform.
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Geo-Tagging Quality-of-Experience Self-Reporting on Twitter to Mobile Network Outage Events
2019 IEEE International Smart Cities Conference (ISC2), 2019Co-Authors: Weijie Qi, Rob Procter, Jie ZhangAbstract:Mobile wireless Networks underpin digital economies and smart cities. Local and national scale Network failures cause widespread social and economic impact. Self-reporting of consumer experience on social media platforms can inform operators. This paper investigates an innovative method to detect the consumer experience to Outage events in both temporal and spatial domain using Twitter data. We use a variety of natural language processing (NLP) analysis to detect the consumer sentiment from a custom made dictionary and using naive Bayes classifier. We propose a hybrid geo-information extraction that sequentially extracts the geo-location from a priority list. A case study upon recent UK wide mobile Network failure has been implemented in this paper. The results show that our proposed hybrid geo-information extraction system has been able to increase data size and accuracy of geo labelled Tweets. Also, our system can successfully detect this Network issue in both time and location, which is validated by the national newspaper reports on this issue.
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dynamic downlink frequency and power allocation in ofdma cellular Networks
IEEE Transactions on Communications, 2012Co-Authors: David Lopezperez, Xiaoli Chu, Jie ZhangAbstract:In order to mitigate inter-cell interference and cope with Network, traffic, and channel fluctuations in space and time, Orthogonal Frequency Division Multiple Access (OFDMA) based cellular Networks should be equipped with dynamic frequency and power allocation algorithms. Although dynamic frequency and power allocation has been well studied separately, very few results have been reported on dynamic joint frequency and power allocation. In this paper, we propose a dynamic frequency and power allocation algorithm for the DownLink (DL) of OFDMA-based cellular Networks, where frequency resources are allocated to cells by a central broker to minimize long-term cell-edge inter-cell interference. Moreover, each cell independently assigns its available frequency resources and power to users in a way that its total DL transmission power is minimized while meeting the throughput demands of its users. Simulation results show that the proposed algorithm provides significant improvements in Network Outage performance, capacity, and throughput as compared with existing schemes.
Goran Strbac - One of the best experts on this subject based on the ideXlab platform.
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quantification and visualisation of extreme wind effects on transmission Network Outage probability and wind generation output
IET Smart Grid, 2020Co-Authors: Magnus R Jamieson, Goran Strbac, Keith BellAbstract:An approach is demonstrated to visualise overhead line failure rates and estimated wind power output during extreme wind events on transmission Networks. Reanalysis data is combined with Network data and line failure models to illustrate spatially resolved line failure probability with data corrected for asset altitude and exposure. Wind output is estimated using a corrected power curve to account for high speed shutdown with wind speed corrected for altitude. Case studies demonstrate these methods' application on representations of real Networks of different scales. The proposed methods allow users to determine at-risk regions of overhead line Networks and to estimate the impact on wind power output. Such techniques could equally be applied to forecasted weather conditions to aid in resilience planning. The methods are shown to be particularly sensitive to the weather data used, especially when modelling risk on overhead lines, but are still shown to be useful as an indicative representation of system risk. The techniques also provide a more robust method of representing weather-related failure rates on lines considerate of the altitude, voltage level, and their varying exposure to weather conditions than current techniques typically provide, which can be used to usefully represent failure probability of lines during storms.
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capacity value of energy storage in distribution Networks
Journal of energy storage, 2018Co-Authors: Ioannis Konstantelos, Goran StrbacAbstract:Abstract Security of supply in electricity distribution Networks has been traditionally delivered by conventional assets such as transformers and circuits to supply energy to consumers. Although non-Network solutions, such as energy storage (ES), can also be used to provide security of supply by carrying out peak shaving and maintaining supply for the duration of a Network Outage, present Network design standards do not provide a framework for quantifying their security contribution and corresponding capacity value. Given the fundamentally different operating principles of ES, it is imperative to develop novel methodologies for assessing its contribution to security of supply and enable a level playing field to be established for future Network planning. To this end, a novel probabilistic methodology based on chronological Monte Carlo simulations is developed for computing the Effective Load Carrying Capability (ELCC) of an energy storage plant. Substantial computational speed-up is achieved through event-based modelling and decomposing between energy and power constraints. The paper undertakes, for the first time, the in-depth analysis of key factors that can affect ES security contribution; plant and Network Outage frequency and duration, Network redundancy level, demand shape, islanding operation capability and ES availability. ES capacity value is shown to decrease in Networks with an unreliable connection to the grid; time to restore supply is shown to be more important that frequency of faults. Capacity value increases in cases of peaky demand profiles, while the ability to operate in islanded conditions is shown to be a critical factor. These findings highlight the need for sophisticated Network design standards. The proposed methodology enables planners to consider ES solutions and allows Network and non-Network assets to compete on an equal basis for security provision.
David Lopezperez - One of the best experts on this subject based on the ideXlab platform.
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dynamic downlink frequency and power allocation in ofdma cellular Networks
IEEE Transactions on Communications, 2012Co-Authors: David Lopezperez, Xiaoli Chu, Jie ZhangAbstract:In order to mitigate inter-cell interference and cope with Network, traffic, and channel fluctuations in space and time, Orthogonal Frequency Division Multiple Access (OFDMA) based cellular Networks should be equipped with dynamic frequency and power allocation algorithms. Although dynamic frequency and power allocation has been well studied separately, very few results have been reported on dynamic joint frequency and power allocation. In this paper, we propose a dynamic frequency and power allocation algorithm for the DownLink (DL) of OFDMA-based cellular Networks, where frequency resources are allocated to cells by a central broker to minimize long-term cell-edge inter-cell interference. Moreover, each cell independently assigns its available frequency resources and power to users in a way that its total DL transmission power is minimized while meeting the throughput demands of its users. Simulation results show that the proposed algorithm provides significant improvements in Network Outage performance, capacity, and throughput as compared with existing schemes.
Tony Q S Quek - One of the best experts on this subject based on the ideXlab platform.
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heterogeneous cellular Network with energy harvesting based d2d communication
IEEE Transactions on Wireless Communications, 2016Co-Authors: Howard H Yang, Jemin Lee, Tony Q S QuekAbstract:The concept of mobile user equipment (UE) relay (UER) has been introduced to support device-to-device (D2D) communications for enhancing communication reliability. However, as the UER needs to use its own power for other UE’s data transmission, relaying information in D2D communication may be undesirable for the UER. To overcome this issue, motivated by the recent advances in energy harvesting (EH) techniques, we propose a D2D communication provided EH heterogeneous cellular Network (D2D-EHHN), where UERs harvest energy from an access point (AP) and use the harvested energy for D2D communication. We develop a framework for the design and analysis of D2D-EHHN by introducing the EH region (EHR) and modeling the status of harvested energy using Markov chain. The UER distribution is derived, and a transmission mode selection scheme including the efficient UER selection method is proposed. The Network Outage probability is derived in close form to measure the performance of D2D-EHHN. Based on our analysis results, we explore the effects of Network parameters on the Outage probability and the optimal offloading bias in terms of the Outage probability. Particularly, we show that having a high EH efficiency enhances the performance of D2D-EHHN, but can also degrade, especially for dense Network.
George K Karagiannidis - One of the best experts on this subject based on the ideXlab platform.
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Outage probability and optimal cache placement for multiple amplify and forward relay Networks
IEEE Transactions on Vehicular Technology, 2018Co-Authors: Lisheng Fan, Nan Zhao, Xianfu Lei, Qingchun Chen, Nan Yang, George K KaragiannidisAbstract:We present a novel framework for analyzing and optimizing the Outage performance of a multiple amplify-and-forward relay Network, where $N$ relays, each with finite cache capacity, are deployed to assist the transmission from a base station equipped with $L$ antennas to the destination. In this Network, if the requested file is cached at the relays and the associated relay channels are in good condition, then the data are directly transmitted from the relays to the destination; otherwise, traditional two-hop transmission is performed. Based on this concept, we propose a relay-selection criterion to choose the best relay, which maximizes the received signal-to-noise ratio at the destination. For this criterion, we derive exact and asymptotic analytical expressions for the system Outage probability in Nakagami- $m$ fading. To further improve the Network Outage performance, we optimize the cache placement, which minimizes the Outage probability. Numerical and simulation experiments are performed to validate the analysis and demonstrate the conditions where the proposed cache placement strategy outperforms the existing ones.