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1.
In the next generation wireless networks, different technologies belonging to one or more operators should be integrated to form a heterogeneous environment based on an IP core network infrastructure. This ensures user mobility and service continuity by maintaining connections when switching between various technologies and it introduces new resources and possibilities for applications. In this context, an automatic interface selection based on instantaneous and practical constraints and user preferences (Quality of Service (QoS) parameters, available resources, security, power consumption, etc.) is therefore required. The different network selection and handover schemes proposed in the literature can be classified into three approaches according to who is responsible for making the handover decision: the terminal, the network or by a cooperation between both of them. However, these approaches keep presenting some drawbacks; namely the problem of resources management and network load balancing whenever the selection is controlled by the mobile terminal (MT) and the problem of scalability and unknown operator's management policy whenever the selection is rather controlled by the network.In this article, first we propose a MIH based approach for handover initiation and preparation for heterogeneous wireless network. The proposed framework is based on the principals of IEEE 802.21 for context information gathering and optimized handover decision making. Second, we propose a new architecture and new network selection scheme that explicitly take into account the current resource usage and the user preferences. Furthermore, our solution ensures the selection of the most suitable network for each flow while taking into consideration its expectations in terms of QoS. A feasibility study of implementing a new architecture on a single MT is evaluated by using typical scenarios and using various algorithms. Thanks to the introduced function entities and modules in the proposed architecture, network utilization balancing and user and application expectations, which are successfully assured without operator intervention. Performance analysis shows that the proposed algorithm best meets the common quality requirements. 相似文献
2.
In the next generation heterogeneous wireless networks, a mobile terminal (MT) with a multi-interface may have network access from different service providers using various technologies. In spite of this heterogeneity, seamless intersystem mobility is a mandatory requirement. One of the major challenges for seamless mobility is the creation of a vertical handover scheme, which is for users that move between different types of networks. In this article a seamless mobility handover scheme is presented. The novelty of the proposed scheme is that handover is fully controlled by the terminal. To improve the performance of the proposed handover scheme, a network discovery algorithm with fuzzy logic and a handover decision algorithm using multi criteria decision making (MCDM) based on vague sets are derived, which are both user-centric. With these algorithms, the handover scheme is power-saving, cost-aware, and performance-aware. Simulation results show that the novel handover scheme can perform network discovery in time to reduce handover dropping rate and present unnecessary activation of its interface to save the battery power, while effectively choose the optimum network through making trade-off among the user preference, network condition, and system performance. 相似文献
3.
Liang Zhou Athanasios V. VasilakosNaixue Xiong Yan ZhangShiguo Lian 《Computer Communications》2011,34(3):429-435
Security is becoming an increasingly important issue in the design of multimedia applications, which are widely used in the industry and academic organizations. However, existing scheduling schemes for real-time multimedia service in heterogeneous networks generally do not take into account security requirements when making allocation and control decisions. In this paper, we develop and evaluate a security-critical multimedia scheduling scheme in the framework of heterogeneous networks. At first, we construct a general media distortion model according to the observed parameters in each network, as well as each application’s characteristic. After that, we exploit a scalable graph-based authentication method which achieves a good trade-off between flexibility and efficiency. Furthermore, a security-critical scheduling scheme is proposed by taking into account applications’ timing and security requirements in addition to precedence constraints. The proposed scheme is applied to heuristically find resource allocations, which maximize the quality of security and the probability of meeting deadlines for all the multimedia applications running on heterogeneous networks. Extensive simulations are provided to demonstrate the effectiveness and feasibility of the proposed scheme. 相似文献
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Peer-to-Peer (P2P) file sharing is the hottest, fastest growing application on the Internet. When designing Gnutella-like
applications, the most important consideration is the scalability problem, because P2P systems typically support millions
of users online concurrently. Gnutella suffers from poor scaling due to its flooding-based search, resulting in excessive
amounts of repeated query messages. Therefore, a good search protocol plays an important role in a system’s scalability. However,
congestion, due to large query loads from users, definitely impacts on the performance of search protocols, and this consideration
has received little attention from the research community. In this paper, we propose a congestion-aware search protocol for
unstructured P2P networks. Our protocol consists of three parts—Congestion-Aware Forwarding, Random Early Stop and Emergency
Signaling. The aim of our protocol is to integrate congestion control and object discovery functionality so that the search
protocol can achieve good performance under congested networks and flash crowds. We perform extensive simulations to study
our proposed protocol. The results show that our protocol can significantly reduce the hit delay while maintaining the high
hit rate and also the congestion problems such as query loss and the peer overloading problem can be effectively alleviated. 相似文献
6.
异质网络将复杂系统中的信息抽象成不同类型的节点和链接关系,不同于同质网络,基于异质网络的社区发现能够挖掘出更加精确的社区结构。异质网络的社区发现通过对异质网络中的多维结构、多模信息、语义信息、链接关系等信息进行建模表示和提取分析,以发现其中相对紧密稳定的社区结构,对网络信息的获取与挖掘、信息推荐以及网络演化预测具有重要的研究价值。首先对社区发现当前研究的不足进行了简单阐述,接着引出了异质网络的定义;随后结合实例介绍了异质网络社区发现的现有研究方法,包括基于主题模型、基于排序和聚类相结合、基于数据重构和基于降维的方法等,并针对各类方法指出了其特点和局限性;最后讨论了当前该领域在结构复杂性、信息多样性、数据规模等方面面临的挑战。在将来,基于并行化、可扩展、动态增量的研究更能适应当前的变化环境。 相似文献
7.
A key challenge for the protection of heterogeneous wireless sensor networks (HWSNs) is how to enable sensor nodes to establish shared cryptographic keys in an authentic and resource-efficient manner for their secure communications. So far, a number of schemes have been developed to address this challenge. However, a main shortcoming of these schemes is that their use of sensor resources is not properly balanced. This has motivated us to propose a new lightweight scheme to rectify the problem. The scheme only employs symmetric cryptosystems for its design. It takes advantage of the hierarchical clustering feature of a HWSN to deliver a novel way of building vertical key shareability before sensor deployment to enable horizontal key shareability after the deployment for authentic shared key establishment. The scheme evaluation shows that it offers strong authenticity and resilience against various security threats, and is more resource-efficient, flexible and scalable than related work. 相似文献
8.
Cameron Nott Semih M. Ölçmen Charles L. Karr Luis C. Trevino 《Applied Intelligence》2007,26(3):251-265
This paper describes the use of artificial intelligence-based techniques for detecting and isolating sensor failures in a
turbojet engine. Specifically, three artificial intelligence (AI) techniques are employed: artificial neural networks (NNs),
statistical expectations, and Bayesian belief networks (BBNs). These techniques are combined into an overall system that is
capable of distinguishing between sensor failure and engine failure—a critical capability in the operation of turbojet engines.
The turbojet engine used in this study is an SR-30 developed by Turbine Technologies. Initially, NNs were designed and trained
to recognize sensor failure in the engine. The increased random noise output from failing sensors was used as the key indicator.
Next, a Bayesian statistical method was used to recognize sensor failure based on the bias error occurring in the sensors.
Finally, a BBN was developed to interpret the results of the NN and statistical evaluations. The BBN determines whether single
or multiple sensor failures signify engine failure, or whether sensor failures represent separate, unrelated incidences. The
BBN algorithm is also used to distinguish between bias and noise errors on sensors used to monitor turbojet performance. The
overall system is demonstrated to work equally well during start-up and main-stage operation of the engine. Results show that
the method can efficiently detect and isolate single or multiple sensor failures within this dynamic environment. 相似文献
9.
《Expert systems with applications》2014,41(15):6738-6747
Due to advances in mobile technology, context-aware applications are continuously growing in importance; therefore, the ability of developing accurate and reliable localization system has become a necessity. Since methods based on received signal strength (RSS) fingerprints are today widely adopted and most of mobile devices comprise different wireless access technologies, it is feasible to use fingerprints from heterogeneous wireless networks (HWN) for localization purposes. In this paper we propose a novel approach for localization based on searching the area which best matches the test RSS fingerprint. We evaluated the proposed method in realistic environment in WLAN, GSM and UMTS networks, and compared it with other commonly used approaches. The results showed that our method compares favorably to others, and practically always achieves the lowest localization error. We also extended the proposed system using a model of cooperative positioning by combining the estimates obtained in the heterogeneous wireless network. The obtained results showed that with combined location estimate, significant improvement over any single system was achieved. 相似文献
10.
Deployment of heterogeneous wireless networks is spreading throughout the world as users want to be connected anytime, anywhere, and anyhow. Meanwhile, these users are increasingly interested in multimedia applications such as video streaming and Voice over IP (VoIP), which require strict Quality of Service (QoS) support. Provisioning network resources with such constraints is a challenging task. In fact, considering the availability of various access technologies (WiFi, WiMAX, or cellular networks), it is difficult for a network operator to find reliable criteria to select the best network that ensures user satisfaction while maximizing network utilization. Designing an efficient Radio Resource Management (RRM), in this type of environment, is mandatory for solving such problems. In order to provide a better understanding of RRM’s design, this paper presents a detailed investigation of key challenges that constitute an efficient RRM framework. More importantly, an overview with a classification of recent solutions, in terms of decision making, is provided along with the discussion. 相似文献
11.
Recent technological advances in wireless networks will enable the realization of an integrated heterogeneous wireless environment consisting of multiple Radio Access Technologies (RATs) within a network provider. One of the most important benefits is that this will allow providers to balance their traffic among their subsystems without compromising on QoS issues. In this paper we focus on the Network Selection problem to allocate terminals to the most appropriate RATs by jointly examining both users’ and providers’ preferences. We introduce three utility-based optimization functions based on the type of application that users request. We then formulate the terminal assignment problem as an optimization problem, which is recognized as NP-hard. We examine both offline and online selection and develop an optimal Branch and Bound (BB) algorithm, a Greedy heuristic, as well as three Strip Packing variations. BB behaves efficiently in both offline and online environments reducing the search procedure, while the proposed heuristics produce results close to the values we get from BB but with very low computational cost. 相似文献
12.
This paper addresses the problem of selecting the best connectivity alternative for the user in a generic Heterogeneous Wireless Multi-hop Network (HWMN), integrating distinct wireless technologies and multi-mode cooperating stations. We propose a Connectivity opportunity Selection Algorithm (CSA) that uses network state information and mobility profile information to select the best connectivity based on the applications’ requirements. We provide a simulation-based performance evaluation of the CSA and compare it with a greedy network selection scheme. Furthermore, we propose an extended reference model that allows the integration of the concept of connectivity opportunity and our proposed CSA with the framework being defined by the upcoming IEEE 802.21 standard for Media Independent Handover services. 相似文献
13.
Key management is an important building block for all security operations in sensor networks. Most existing key management schemes try to establish shared keys for all pairs of neighbor sensors; hence, a large number of keys need to be preloaded on each sensor, which necessitates a large key space for the nodes in the network. The recent trend in research is to mainly consider homogeneous sensor networks, and to a lesser degree heterogeneous sensor networks, for key management. In this paper, we propose a novel key agreement protocol which is based on pairing-based cryptography over an elliptic curve. Using this protocol, any two nodes that need to communicate can independently compute the same secret key by using pairing and identity-based encryption properties. The proposed protocol significantly reduces the key space of a node. Additionally, the security analysis of the proposed protocol shows that it is robust against a number of attacks including wormhole attack, masquerade attacks, reply attacks, and message manipulation attacks. 相似文献
14.
This paper addresses the explicit synchronisation of heterogeneous dynamics networks via three-layer communication framework. The main contribution is to propose an explicit synchronisation algorithm, in which the synchronisation errors of all the agents are decoupled. By constructing a three-layer node model, the proposed algorithm removes the assumptions that the topology is fixed and the synchronisation process is coupled. By introducing appropriate assumptions, the algorithm leads to a class of explicit synchronisation protocols based on the states of agents in different layers. It is proved in the sense of Lyapunov that, if the dwell time is larger than a threshold, the explicit synchronisation can be achieved for closed-loop heterogeneous dynamics networks under switching topologies. The results are further extended to the cases in which the switching topologies are only frequently but not always connected. Simulation results are presented with four single-link manipulators to verify the theoretical analysis. 相似文献
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Several three-party password authenticated key exchange (3-PAKE) protocols have recently been proposed for heterogeneous wireless sensor networks (HWSN). These are efficient and designed to address security concerns in ad-hoc sensor network applications for a global Internet of Things framework, where a user may request access to sensitive information collected by resource-constrained sensors in clusters managed by gateway nodes. In this paper we first analyze three recently proposed 3-PAKE protocols and discuss their vulnerabilities. Then, based on Radio Frequency Identification technologies we propose a novel 3-PAKE protocol for HWSN applications, with two extensions for additional security features, that is provably secure, efficient and flexible. 相似文献
17.
分布式时间同步技术是无线传感器网络(WSNs)应用中的一项重要支撑技术,保证时间同步的安全性至关重要。针对敌对异构网络环境,通过利用存储有高能量的高级传感器,提出了一种高效的异构WSNs时间同步安全方案。Tmote传感器节点实验表明:该方案比现有的同步方案更能有效提高同步精度,减少通信开销和抵御网络的多种攻击。 相似文献
18.
Heterogeneous networks, such as bibliographical networks and online business networks, are ubiquitous in everyday life. Nevertheless, analyzing them for high-level semantic understanding still poses a great challenge for modern information systems. In this paper, we propose HiWalk to learn distributed vector representations of the nodes in heterogeneous networks. HiWalk is inspired by the state-of-the-art representation learning algorithms employed in the context of both homogeneous networks and heterogeneous networks, based on word embedding learning models. Different from existing methods in the literature, the purpose of HiWalk is to learn vector representations of the targeted set of nodes by leveraging the other nodes as “background knowledge”, which maximizes the structural correlations of contiguous nodes. HiWalk decomposes the adjacent probabilities of the nodes and adopts a hierarchical random walk strategy, which makes it more effective, efficient and concentrated when applied to practical large-scale heterogeneous networks. HiWalk can be widely applied in heterogeneous networks environments to analyze targeted types of nodes. We further validate the effectiveness of the proposed HiWalk through multiple tasks conducted on two real-world datasets. 相似文献
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20.
Ananya Gupta Anindo Mukherjee Bin Xie Dharma P. Agrawal 《Journal of Parallel and Distributed Computing》2007
With the support of cellular system a cellular-based mobile ad hoc network (MANET) offers promising communication scenarios while entails secure data exchange as other wireless systems. In this paper, we propose a novel decentralized key generation mechanism using shared symmetric polynomials in which the base stations (BSs) carry out an initial key generation by a symmetric polynomial in a distributed manner and then pass on the key material to mobile stations (MSs). Thereafter, our proposed key generation scheme enables each pair of MSs to establish a pairwise key without any intervention from the BS, thus reducing the management cost for the BS. The shared key between two MSs is computed without any interaction between them. In addition, the trust among MSs is derived from the cellular infrastructure, thus enjoying an equal security level as provided in the underlying cellular network. Simulations are done to observe the system performance and the results are very encouraging. 相似文献