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Review: Real-time data management on wireless sensor networks: A survey

In the recent past, search in sensor systems focused on node hardware constraints and very limited energy resources. But nowadays, that new applications need data processing with temporal constraints in their tasks; then one of the new challenges faced by wireless sensor networks (WSNs) is handling real-time storage and querying the data they process. Two main approaches to storage and querying data are generally considered warehousing and distributed. The warehousing approach stores data in a central database and then queries may be performed to it. In a distributed approach, sensor devices are considered as local databases and data are managed locally. The data collected by sensors must represent the current state of the environment; for this reason they are subject to logic and time constraints. Then, this paper identifies the main specifications of real-time data management and presents the available real-time data management solutions for WSNs, in order to discuss them and identify some open issues and provide guidelines for further contributions.

Distributed Database Management Techniques for Wireless Sensor Networks

In sensor networks, the large amount of data generated by sensors greatly influences the lifetime of the network. To manage this amount of sensed data in an energy-efficient way, new methods of storage and data query are needed. In this way, the distributed database approach for sensor networks is proved as one of the most energy-efficient data storage and query techniques. This paper surveys the state of the art of the techniques used to manage data and queries in wireless sensor networks based on the distributed paradigm. A classification of these techniques is also proposed. The goal of this work is not only to present how data and query management techniques have advanced nowadays, but also show their benefits and drawbacks, and to identify open issues providing guidelines for further contributions in this type of distributed architectures.

Real-time query processing optimization for cloud-based wireless body area networks

Abstract Wireless body area networks (WBANs) have received a lot of attention from both academia and industry due to the increasing need of ubiquitous computing for eHealth applications, the continuous advances in miniaturization of electronic devices, and the ultra-low-power wireless technologies. In these networks, various sensors are attached either on clothes, on human body or even implanted under the skin for real-time health monitoring of patients in order to improve their independent daily lives. The energy constraints of sensors, the vital and large amount of data collected by WBAN nodes require powerful and secure storage, and a query processing mechanism that takes into account both real-time and energy constraints. This paper addresses these challenges and proposes a new architecture that combines a cloud-based WBANs with statistical modeling techniques in order to provide a secure storage infrastructure and optimize the real-time user query processing in terms of energy minimization and query latency. Such statistical model provides good approximate answers to queries with a given probabilistic confidence. Furthermore, the combination of the model with the cloud-based WBAN allows performing a query processing algorithm that uses the error tolerance and the probabilistic confidence interval as query execution criterions. The performance analysis and the experiments based on both real and synthetic data sets demonstrate that the new architecture and its underlying proposed algorithm optimize the real-time query processing to achieve minimal energy consumption and query latency, and provide secure and powerful storage infrastructure.

Call Admission Control Performance Analysis in Mobile Networks Using Stochastic Well-Formed Petri Nets

(This work is an extension of our conference paper at Valuetools 2006 [18].) Stochastic Well-formed Petri Nets (SWNs) are a powerful tool for modeling complex systems with concurrency, synchronization, and cooperation. Call Admission Control (CAC) is an important mechanism for mobile networks. While several studies have been done on GSM/GPRS and on UMTS system with mixed voice and data, to the best of our knowledge, limited CAC models for mobile networks that have been proposed in the literature are represented with a unidimensional Markov chain, where the communication system was mainly based upon voice calls in order to reduce the state space of the Markov chain. Another drawback of those studies is the lack of a clear synchronization between mobile nodes and the servers. In this paper, we propose an efficient CAC scheme for mobile networks that takes into account voice connections as well as synchronous and asynchronous data connections. Furthermore, we use SWNs to model the system interaction, which consists of several mobile nodes, gateways, cells, and servers. We describe our scheme and present its analytical performance results using the WNSIM symbolic simulator of GreatSPN tool.

Performance measures of a call admission control in mobile networks using SWN

Call Admission Control (CAC) is an important mechanism in mobile networks. Many works have been done on GSM/GPRS and on UMTS system with mixed voice and data. However, CAC models and wireless communication proposed in the literature are represented with a uni-dimensional Markov chain, in general based on voice calls in order to reduce the state-space of the chain. Another drawback of those studies is lack of the synchronization between mobiles and servers. In this paper, we aim to evaluate the performance of a CAC scheme which takes into account voice connections, synchronous and asynchronous data connections. This scheme can be represented by a multi-dimensional Markov chain with a very large state-space. Thus, we propose to use Stochastic Well formed Petri Nets (SWN) to model the system interaction which consists of several mobiles, gateways, cells and servers. Performance measures are carried-out using symbolic simulation.

Load Balancing Approach for QoS Management of Multi-instance Applications in Clouds

The success of the technology of cloud computing lies mainly in its business model of pay-as-you-go where users pay only for the resources really consumed. However it is known that there is no warranty for the QoS that these resources will provide at runtime. In this paper, we suggest an approach to make load balancing more dynamic to better manage the QoS of multi-instance applications in the Clouds. This approach is based on limiting the number of requests that, at a given time, can be effectively sent and stored in queues of virtual machines through a load balancer equipped with a queue for incoming user requests. This limitation is intended on the one hand to allow requests to go on to the faster instances, and on the other hand to better mitigate the effects of interference of sharing resources by the fact that a large part of the requests which were intended to instances that have become affected by degradation are still stored at the load balancer and can be allocated to non-affected instances or to new instances which will be created. A performance study using the simulator CloudSim showed the gain that this approach can generate, compared to classical approaches of load balancing.

Performance analysis of Web services architecture

Web services are very present in computing today. Several studies are being conducted in the context of Web services: specifications, security, performance measures and so on. In this paper, we propose an analytical model based on multiple-class queueing network to evaluate the performance of Web service architecture. Numerical results are given for considered performance measures.

Freshness-aware metadata management: Performance evaluation with SWN models

Recent systems which are in general composed by several resources and distributed over a large-scale network, need high-level models to be studied. In these complex systems such as peer-to-peer systems, efficient and fast query routing is necessary for managing applications workload. Many works have been proposed to deal with query routing, however none of these studies rely on Stochastic Well formed Petri Nets (SWN) for modelling the approach proposed. We aim in this paper, to propose an algorithm for managing metadata needed to route queries. Moreover we use SWN models to evaluate and validate our approach. Our solution is freshness-aware, thus gains in the fact that stale data can be read under some limits. These limits are wideley taken into account for managing metadata coherently. Our study takes into account the concurrency, the synchronization, the parallelism, the identity of the resources and their cooperation. We propose two SWN models for structuring metadata: one with strong consistency and another with weak consistency. Simulations are used to validate our approach and the results obtainded demonstrate the fesability of our solution.

Performance analysis of composite web services using Stochastic Automata Networks over IP network

The emergence and success of IP networks make the development of new services like voice, multimedia or web services possible. One of the major problem of these type of application is that IP networks is not designed to provide Quality of Service (QoS) in an end to end architecture. Thus the performance evaluation of these applications is important to guarantee a high level of QoS. We focus in this study to evaluate the performance evaluation ofWeb services which is the most difficult to achieve because of the complexity of their architectures. The classical mathematical formalisms such as queueing networks can not be used in this kind of problems due the synchronization events and the state space explosion. In this paper we propose to use an adequate and efficient modelling tool: the Stochastic Automata Network (SAN) to evaluate the performance of Web services architecture over IP networks. Numerical results using PEPS are given for considered performance measures.

Stabilizing Agent's Interactions in Dynamic Contexts

We address the problem of efficient coordination protocols in the contexts where mobile and ad-hoc devices which harbor the selfish agents must achieve a set of dynamic tasks. This work assumes that, due to the dynamic behaviors of the agents induced by the unpredictable availability of these devices and the dynamic of the tasks, it is not possible to devise an efficient coordination which uses prior knowledge about the information of the agents ahead of task achievements. In these contexts, we provide both protocols called depth exploration protocol and width exploration protocol which are based on the formalism of the MDP (Markov Decision Process) and on alliance principle. The aim of our protocols is to ensure and to adapt dynamically the stability of the agents coordination teams (coalitions) which take into account the agents withdrawal and the dynamic evolving of the tasks. We develop a theoretical study of our mechanism and we provide an analytical and experimental performance evaluation.