Context-Aware Handover Policies in HetNets

Next generation cellular systems are expected to entail a wide variety of wireless coverage zones, with cells of different sizes and capacities that can overlap in space and share the transmission resources. In this scenario, which is referred to as Heterogeneous Networks (HetNets), a fundamental challenge is the management of the handover process between macro, femto and pico cells. To limit the number of handovers and the signaling between the cells, it will hence be crucial to manage the user's mobility considering the context parameters, such as cells size, traffic loads, and user velocity. In this paper, we propose a theoretical model to characterize the performance of a mobile user in a HetNet scenario as a function of the user's mobility, the power profile of the neighboring cells, the handover parameters, and the traffic load of the different cells. We propose a Markov-based framework to model the handover process for the mobile user, and derive an optimal context-dependent handover criterion. The mathematical model is validated by means of simulations, comparing the performance of our strategy with conventional handover optimization techniques in different scenarios. Finally, we show the impact of the handover regulation on the users performance and how it is possible to improve the users capacity exploiting context information

A study on the coexistence of fixed satellite service and cellular networks in a mmWave scenario

The use of a larger bandwith in the millimeter wave (mmWave) spectrum is one of the key components of next generation cellular networks. Currently, part of this band is allocated on a co-primary basis to a number of other applications,such as the fixed satellite services (FSSs). In this paper, we investigate the coexistence between a cellular network and FSSs in a mmWave scenario. In light of the parameters recommended by the standard and the recent results presented in the literature on the mmWave channel model, we analyze different BSs deployments and different antenna configurations at the transmitters. Finally, we show how, exploiting the features of a mmWave scenario, the coexistence between cellular and satellite services is feasible and the interference at the FSS antenna can be kept below recommended levels

Two-Objective Design of Benchmark Problems of a Water Distribution System via MOEAs: Towards the Best-Known Approximation of the True Pareto Front

Copyright © 2015 American Society of Civil EngineersVarious multiobjective evolutionary algorithms (MOEAs) have been applied to solve the optimal design problems of a water distribution system (WDS). Such methods are able to find the near-optimal trade-off between cost and performance benefit in a single run. Previously published work used a number of small benchmark networks and/or a few large, real-world networks to test MOEAs on design problems of WDS. A few studies also focused on the comparison of different MOEAs given a limited computational budget. However, no consistent attempt has been made before to investigate and report the best-known approximation of the true Pareto front (PF) for a set of benchmark problems, and thus there is not a single point of reference. This paper applied 5 state-of-the-art MOEAs, with minimum time invested in parameterization (i.e., using the recommended settings), to 12 design problems collected from the literature. Three different population sizes were implemented for each MOEA with respect to the scale of each problem. The true PFs for small problems and the best-known PFs for the other problems were obtained. Five MOEAs were complementary to each other on various problems, which implies that no one method was completely superior to the others. The nondominated sorting genetic algorithm-II (NSGA-II), with minimum parameters tuning, remains a good choice as it showed generally the best achievements across all the problems. In addition, a small population size can be used for small and medium problems (in terms of the number of decision variables). However, for intermediate and large problems, different sizes and random seeds are recommended to ensure a wider PF. The publicly available best-known PFs obtained from this work are a good starting point for researchers to test new algorithms and methodologies for WDS analysis

Formulation of fast 2D urban pluvial flood model using cellular automata approach

Copyright © 2013 IWA Publishing. The definitive peer-reviewed and edited version of this article is published in Journal of Hydroinformatics Vol 15 (3), pp. 676–686 (2013), DOI: 10.2166/hydro.2012.245 and is available at www.iwapublishing.comWith the increase in frequency and severity of flash flood events in major cities around the world, the infrastructure and people living in those urban areas are exposed continuously to high risk levels of pluvial flooding. The situation is likely to be exacerbated by the potential impact of future climate change. A fast flood model could be very useful for flood risk analysis. One-dimensional (1D) models provide limited information about the flow dynamics whereas two-dimensional (2D) models require substantial computational time and cost, a factor that limits their use. This paper presents an alternative approach using cellular automata (CA) for 2D modelling. The model uses regular grid cells as a discrete space for the CA setup and applies generic rules to local neighbourhood cells to simulate the spatio-temporal evolution of pluvial flooding. The proposed CA model is applied to a hypothetical terrain and a real urban area. The synchronous state updating rule and inherent nature of the proposed model contributes to a great reduction in computational time. The results are compared with a hydraulic model and good agreement is found between the two models.Engineering and Physical Sciences Research Council (EPSRC

CADDIES: A New Framework for Rapid Development of Parallel Cellular Automata Algorithms for Flood Simulation

CADDIES project CA Framework conference paper presented at HIC2012A recent trend in the development of flood simulation algorithms shows the move toward fast simplified models instead of slow full hydrodynamic models. CADDIES is a research project that aims to develop a real/near-real time pluvial urban flood simulation model using the computational speed of cellular automata (CA) algorithms. This paper presents a component of the software framework that is part of the CADDIES project. Its objective is to simplify the development of CA algorithms and their acceleration using modern high performance hardware and techniques. The performance results obtained on a simple case study clearly demonstrate the effectiveness and efficiency of the CADDIES framework.EPSR

The Battle of the Water Networks II (BWN-II)

The Battle of the Water Networks II (BWN-II) is the latest of a series of competitions related to the design and operation of water distribution systems (WDSs) undertaken within the Water Distribution Systems Analysis (WDSA) Symposium series. The BWN-II problem specification involved a broadly defined design and operation problem for an existing network that has to be upgraded for increased future demands, and the addition of a new development area. The design decisions involved addition of new and parallel pipes, storage, operational controls for pumps and valves, and sizing of backup power supply. Design criteria involved hydraulic, water quality, reliability, and environmental performance measures. Fourteen teams participated in the Battle and presented their results at the 14th Water Distribution Systems Analysis (WDSA 2012) conference in Adelaide, Australia, September 2012. This paper summarizes the approaches used by the participants and the results they obtained. Given the complexity of the BWN-II problem and the innovative methods required to deal with the multi-objective, high dimensional and computationally demanding nature of the problem, this paper represents a snap-shot of state of the art methods for the design and operation of water distribution systems. A general finding of this paper is that there is benefit in using a combination of heuristic engineering experience and sophisticated optimization algorithms when tackling complex real-world water distribution system design problems.Angela Marchi...Angus R. Simpson, Aaron C. Zecchin, Holger R. Maier...Christopher Stokes, Wenyan Wu, Graeme C. Dandy...et al

The Battle of the Water Networks II (BWN-II)

The Battle of the Water Networks II (BWN-II) is the latest of a series of competitions related to the design and operation of water distribution systems (WDSs) undertaken within the Water Distribution Systems Analysis (WDSA) Symposium series. The BWN-II problem specification involved a broadly defined design and operation problem for an existing network that has to be upgraded for increased future demands, and the addition of a new development area. The design decisions involved addition of new and parallel pipes, storage, operational controls for pumps and valves, and sizing of backup power supply. Design criteria involved hydraulic, water quality, reliability, and environmental performance measures. Fourteen teams participated in the Battle and presented their results at the 14th Water Distribution Systems Analysis (WDSA 2012) conference in Adelaide, Australia, September 2012. This paper summarizes the approaches used by the participants and the results they obtained. Given the complexity of the BWN-II problem and the innovative methods required to deal with the multi-objective, high dimensional and computationally demanding nature of the problem, this paper represents a snap-shot of state of the art methods for the design and operation of water distribution systems. A general finding of this paper is that there is benefit in using a combination of heuristic engineering experience and sophisticated optimization algorithms when tackling complex real-world water distribution system design problems.Angela Marchi...Angus R. Simpson, Aaron C. Zecchin, Holger R. Maier...Christopher Stokes, Wenyan Wu, Graeme C. Dandy...et al

Grid-Enabled Hydropad: a Scientific Application for Benchmarking GridRPC-Based Programming Systems

GridRPC is a standard API that allows an application to easily interface with a Grid environment. It implements a remote procedure call with a single task map and client-server communication model. In addition to non-performance-related benefits, scientific applications having large computation and small communication tasks can also obtain important performance gains by being implemented in GridPRC. However, such convenient applications are not representative of the majority of scientific applications and therefore cannot serve as fair benchmarks for comparison of the performance of different GridRPC-based systems. In this paper, we present Hydropad, a real life astrophysical simulation, which is composed of tasks that have a balanced ratio between computation and communication. While Hydropad is not the ideal application for performance benefits from its implementation with GridRPC middleware, we show how even its performance can be improved by using GridSolve and SmartGridSolve. We believe that the Grid-enabled Hydropad is a good candidate application to benchmark GridRPC-based programming systems in order to justify their use for high performance scientific computing.Science Foundation Irelan