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The shop scheduling problem with which this paper is concerned is to determine a sequence of J jobs on each of the M machines such that the schedule time is minimized. The machine ordering of each job is pre-specified but independent of those of other jobs. A branch-and-bound algorithm, using a powerful bounding procedure, has been developed for obtaining an optimal solution. An illustrative example is solved. Computational experience with this algorithm shows that it is practical in problems of moderate size. However, for larger problems, the algorithm can be applied without backtracking in which an optimal or near-optimal solution may be obtained. The quality of solutions obtained by the branch-and-bound algorithm without backtracking has been investigated. The optimal-producing algorithm is compared favourably with other published methods The number of nodes explored and the computational time are considered as bases for evaluation. [ABSTRACT FROM AUTHOR]

NDN is one instance of ICN, which is a cleanslate approach that promises to reduce inefficiencies in the current Internet. NDN provides intelligent data retrieval using the principles of name-based symmetrical forwarding of Interest/ Data packets and in-network caching. The continually increasing demand for the rapid dissemination of large-scale scientific data is driving the use of NDN in big science experiments. In this article, we establish the first intercontinental NDN testbed to offer complete insight into NDN construction for big science. In the testbed, an NDN-based application that targets climate science as an example big-science application is designed and implemented with differentiated features compared to previous works on NDNbased application design for big science. We first attempt to systematically address detailed analysis of why or how NDN benefits fit in big science and issues that must be resolved to improve each advantage, mostly based on lessons learned from establishing the NDN testbed for climate science. We extensively justify the needs of using NDN for large-scale scientific data in the intercontinental network, through experimental performance comparisons between classical deliveries and NDNbased climate data delivery, and detailed analysis of why or how NDN benefits fit in big science. [ABSTRACT FROM AUTHOR]

Cloud storage and computing, although it empowers ubiquitous and global information acquisition, analysis, and management, the latency performance and heavy traffic burdens at fronthaul/ hackhaul links have emerged as critical concerns due to the scalability issue, which consequently drives the development of edge content cache and dissemination. Despite ample research on latency and traffic load reduction, an effective design of edge content cache and dissemination from the perspective of energy efficiency is imperative. Noting the fact that wireless service demands are inherently unbalanced over geographic regions, a practical cell planning strategy of operators' basic interests should deploy base stations massively in hot spot areas and sparsely in rural areas. A mobile user is therefore able to acquire desired contents through multiple base stations in a hot spot, while performing autonomous content cache and dissemination with other mobile users in rural areas. Taking this practical constraint into consideration, this article offers energy-optimal edge content cache and dissemination designs for hot spot and rural areas. Exploiting Lyapunov optimization and optimum control theory, we demonstrate analytical foundations and principles of the proposed optimum designs. Engineering insights are also revealed through practical simulation investigations to extend the research frontier of energy-efficient edge content cache and dissemination. [ABSTRACT FROM PUBLISHER]

Software-Defined Networking (SDN) promises the vision of more flexible and manageable networks but requires certain level of programmability in the data plane to accommodate different forwarding abstractions. SDN software switches running on commodity multicore platforms are programmable and are with low deployment cost. However, the performance of SDN software switches is not satisfactory due to the complex forwarding operations on packets. Moreover, this may hinder the performance of real-time security on software switch. In this paper, we analyze the forwarding procedure and identify the performance bottleneck of SDN software switches. An FPGA-based mechanism for accelerating and securing SDN switches, named FAS (FPGA-Accelerated SDN software switch), is proposed to take advantage of the reconfigurability and high-performance advantages of FPGA. FAS improves the performance as well as the capacity against malicious traffic attacks of SDN software switches by offloading some functional modules. We validate FAS on an FPGA-based network processing platform. Experiment results demonstrate that the forwarding rate of FAS can be 44% higher than the original SDN software switch. In addition, FAS provides new opportunity to enhance the security of SDN software switches by allowing the deployment of bump-in-the-wire security modules (such as packet detectors and filters) in FPGA. [ABSTRACT FROM AUTHOR]

We consider a network design problem with random arc capacities and give a formulation with a probabilistic capacity constraint on each cut of the network. To handle the exponentially-many probabilistic constraints a separation procedure that solves a nonlinear minimum cut problem is introduced. For the case with independent arc capacities, we exploit the supermodularity of the set function defining the constraints and generate cutting planes based on the supermodular covering knapsack polytope. For the general correlated case, we give a reformulation of the constraints that allows to uncover and utilize the submodularity of a related function. The computational results indicate that exploiting the underlying submodularity and supermodularity arising with the probabilistic constraints provides significant advantages over the classical approaches. © 2017 Wiley Periodicals, Inc. NETWORKS, Vol. 71(1), 16-30 2018 [ABSTRACT FROM AUTHOR]

Through interviews and induction, this paper attempts to discuss the importance of college English teaching methods in the teaching process under the network context and point out issues like teacher's inadequate awareness and abilities of collecting network resources and information and insufficient background monitoring on students' study activities. Based on this, this paper proposes that college English teachers should free their minds, change their views and improve their network operation skills to know more about students' study activities and update their knowledge bases to improve their own quality so as to redefine their roles under the network context. [ABSTRACT FROM AUTHOR]

This paper examines the effect of incorporating multi-period network augmentation into the survivable network design process. The framework presented can handle variable restorability requirements, potential economies of scale, and technology shifts. By utilizing a multi-period planning model, shifts and uncertainties in demand and policy can be accounted for. This study examined the design of survivable networks using both demand-wise shared protection and shared backup path protection (representing opposite ends of the mesh network efficiency spectrum) with topology augmentation over multiple time horizons. [ABSTRACT FROM AUTHOR]

JUNE 2013 Uttarakhand flash-flood killed nearly 5700 people and trapped 110,000. The disaster caused a black-out, leading to a serious network failure which delayed rescue work in isolated areas. The lack of robust communication network has become a sizable topic for scrutiny of disaster inflicted area network system. Thus, it is important to design a network which never fails during such crisis. In this paper, a detailed survey of AONs (Always-On Network) is done and issues in implementation of those are highlighted. The architecture of existing networks has several practical issues in case of emergency which need to be addressed. [ABSTRACT FROM AUTHOR]

In the current phase of the IPv6 transition, it is a typical situation that IPv6-only clients should be enabled to communicate with IPv4-only servers. The DNS64+NAT64 tool suite is an excellent solution to this problem. Although several free software DNS64 implementations exist, we point out that there is room for further high performance and computation efficient multithreaded DNS64 implementations. MTD64 was designed to be able to utilize several CPU cores. Whereas MTD64 outperformed BIND more than five times, two critical issues (memory leaking and potential vulnerability to DoS attacks) were identified. Therefore MTD64 was redesigned under a new name: mtd64-ng (not capitalized). This paper is about the design, implementation and initial performance estimation of mtd64-ng. The usage of object oriented decomposition and the RAII (Resource Acquisition Is Initialization) idiom ensures that raw, sensitive resources (e.g. memory, sockets) are always released and it greatly simplifies exception handling. Using the new features of the C++11 standard enabled us to write more efficient and better readable code. The performance of mtd64-ng is compared to that of BIND and MTD64 and it is found that mtd64-ng outperforms even its predecessor, MTD64. [ABSTRACT FROM AUTHOR]

Many applications collect a large number of time series, for example, the financial data of companies quoted in a stock exchange, the health care data of all patients that visit the emergency room of a hospital, or the temperature sequences continuously measured by weather stations across the US. These data are often referred to as un structured. The first task in its analytics is to derive a low dimensional representation, a graph or discrete manifold, that describes well the interrelations among the time series and their intra relations across time. This paper presents a computationally tractable algorithm for estimating this graph that structures the data. The resulting graph is directed and weighted, possibly capturing causal relations, not just reciprocal correlations as in many existing approaches in the literature. A convergence analysis is carried out. The algorithm is demonstrated on random graph datasets and real network time series datasets, and its performance is compared to that of related methods. The adjacency matrices estimated with the new method are close to the true graph in the simulated data and consistent with prior physical knowledge in the real dataset tested. [ABSTRACT FROM PUBLISHER]

Many social spreading phenomena can be modeled as epidemic spreading models over networks, and the studies of these phenomena are important to avoid epidemic outbreaks. Epidemic threshold of the network, which fundamentally depends on the network structure itself, is a critical measure to judge whether the epidemic dies out or results in an epidemic breakout. In this study, epidemic threshold is regarded as the objective function to control the spreading process. In addition, an efficient structure optimization strategy based on memetic algorithm is proposed to adjust the spreading threshold without changing the degree of each node. Lowering the threshold can promote the spreading process whereas heightening the threshold can prevent the spreading process. In the proposed algorithm, genetic algorithm is adopted as the global search strategy and a modified simulated annealing algorithm combined with the properties of networks is proposed as the local search strategy. Experiments on computer-generated and real-world networks demonstrate that the proposed algorithm has superior performances for both the threshold minimization and maximization problems. [ABSTRACT FROM AUTHOR]

Joint FoUntain coding and Network coding (FUN) is proposed to boost information spreading over multi-hop lossy networks. The novelty of our FUN approach lies in combining the best features of fountain coding, intra-session network coding, and cross-next-hop network coding. This paper provides an in-depth study of FUN codes. First, we theoretically analyze the throughput of FUN codes. Second, we identify several practical issues that may undermine the actual performance, such as buffer overflow, and quantify the resulting throughput degradation. Finally, we propose a systematic design to overcome these issues. Simulation results in TDMA multi-hop networks show that our methods yield near-optimal throughput and are significantly better than fountain codes and existing network coding schemes. [ABSTRACT FROM PUBLISHER]

In direct communication, in order to deliver synchronization information to mobile terminals outside the coverage area of the base station, some terminals should propagate the synchronization signal through the synchronization channel. In general, a mobile terminal transmits a synchronization signal based on the received synchronization signal. If the received signal strength is below the propagation threshold, the mobile terminal sends a synchronization signal to extend the coverage of the direct communication network. Therefore, the propagation threshold value is closely related to the performance of direct communication networks. If the threshold value is too low, only a minimal number of terminals transmit synchronization information. Thus, the coverage of that direction communication network is limited. On the other hand, if the threshold value is too high, most terminals will transmit synchronization messages, triggering collisions. However, it is difficult to find the optimal propagation threshold value over the entire direct communication network. Therefore, we propose a heuristic method for finding the most efficient threshold value after declaring the decision variables. The proposed method minimizes the probability of collisions between the mobile terminals' signals on the synchronization channel. By comparing our simulation results with the numerical ones, we show the validity of the proposed synchronization method. [ABSTRACT FROM AUTHOR]

This article is devoted to the search for a generating function for network delay simulation. We justify the choice of the measurement system used to collect delay data with microsecond accuracy. Experimental data are employed in order to form a hypothesis regarding the exponential type of delay. The paper is restricted to the study of the simplest two cases: the linear and quadratic dependence of the delay distribution function. The application of the Pearson criterion led to the conclusion that an exponential distribution can be used to describe network delay, but is valid only for small periods from 10 to 30 minutes. We also justify the expression for the distribution function and generating function for further theoretical and experimental calculations. [ABSTRACT FROM AUTHOR]

A key advance in enabling higher wireless mesh network capacity is allowing routers to transmit or receive (MTR) from multiple neighbors simultaneously over the same frequency. Achieving this capacity, however, is predicated on a link scheduler that is able to capitalize on the MTR capability of nodes to activate the maximum number of active links, and also to derive the shortest schedule that ensures all links are activated at least once. To date, existing schedulers do not consider the transmission or air-time of packet(s). Henceforth, this paper fills this gap and propose to derive the shortest superframe length, defined as the end time of the last transmitting link. Our scheduler, called A-TxRx, greedily adds links whenever a link finishes its transmission. As a result, unlike previous schedulers, links can start transmitting/receiving as soon as there is no conflict. We have evaluated the performance of A-TxRx in various network configurations, and compared it against two state-of-the-art approaches: 2P and JazzyMAC. The results show A-TxRx outperforming these algorithms significantly, especially when the network becomes denser. Specifically, the superframe length of A-TxRx is typically less than half of 2P and JazzyMAC, with 60 % more concurrently transmitting links. [ABSTRACT FROM AUTHOR]

Instruction Register File (IRF) was originally proposed to reduce the power consumption of a microprocessor by providing the indirect access to frequently executed instructions. The IRF is also an attractive and cost-effective unit to protect embedded software from analysis, plagiarism, and falsification. For this purpose, the correspondences between IRF entries and their original instructions must be concealed. This means the instructions in the IRF should be carefully selected both to have more instructions be executed through the IRF and to flatten the distribution of the indices of the IRF. This paper presents two heuristic algorithms, precision-oriented and time-oriented, to find sub-optimal assignments to the IRF. According to the evaluation results, the precision-oriented algorithm obtained the same as or very close to the optimal assignment of an IRF with 48 or less entries. The time-oriented algorithm found a sub-optimal assignment of a 1024-entry IRF in 16 ms, whose precision was 0.5% inferior to the precision-oriented solution at a maximum. The hardware cost of a 1024-entry IRF on an FPGA was modest: two 18 kib block RAM elements and 0.8% increase of the logic elements. [ABSTRACT FROM AUTHOR]

We propose a new ultra-lightweight block cipher, QTL. The 64 bits block cipher QTL supports 64 and 128 bits keys. To solve the slow diffusion of the traditional Feistel-type structures we have used a new variant of generalized Feistel network structure in design of the QTL. Traditional Feistel-type structures change only half of block messages in an iterative round, but our structure overcomes this disadvantage and changes all block messages. Thus, our structure has the fast diffusion of the Substitution Permutation Networks (SPNs) structures, which improves the security of lightweight block cipher in Feistel-type structures. Moreover, QTL algorithm has the same encryption and decryption processes, so it will occupy less area in resource-constrained applications. Furthermore, to reduce the cost of energy consumption in hardware implementation of the cipher while maintaining security, we decide not to use a key schedule. We show that QTL offers an adequate security level against classic analyses. Our hardware implementation for the 64 and the 128 bits keys modes only require 1025.52 and 1206.52 gate equivalents, respectively. QTL achieves high security and compact implementation in hardware. QTL is one of the most competitive ultra-lightweight block ciphers, which is suitable for extremely constrained devices. [ABSTRACT FROM AUTHOR]

Presents key events and topics in the global communications industry. [ABSTRACT FROM PUBLISHER]

Communications on hierarchical heterogeneous high-performance computing platforms can be optimized based on topology and performance information. For MPI, as a major programming tool for such platforms, a number of topology-aware and performance-aware implementations of collective operations have been proposed for optimal scheduling of messages. This approach improves performance of application and does not require to modify application source code. However, it is applicable to collective operations only and does not affect the parts of the application that are based on point-to-point exchanges. In this paper, we address the problem of efficient execution of data-parallel applications on interconnected clusters and present optimizations that improve data partition by taking into account the entire communication flow of the application. This approach is also non-intrusive to the source code but application specific. For illustration, we use parallel matrix multiplication, where the matrices are partitioned into irregular two-dimensional rectangles assigned to different processors and arranged in columns, and the processors communicate over this partition vertically and horizontally. By rearranging the rectangles, we can minimize communications between different levels of the network hierarchy. Finding the optimal arrangement is NP-complete; therefore, we propose two heuristic approaches based on evaluation of the communication flow on the given network topology. We demonstrate the correctness and efficiency of the proposed approaches by experimental results on multicore nodes and interconnected heterogeneous clusters. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Two critical issues in networked control systems are coupling of control and communication, and energy economy, especially for battery powered wireless sensor nodes. In this regard, a two-level design procedure for multiple loops with H ∞ based self-triggered control applied over the modified IEEE 802.15.4 wireless protocol is presented. Control and communication are decoupled by introducing an upper-bound on the transmission rate, and optimal usage of communication bandwidth and energy is guaranteed by modifying the wireless protocol. The presented priority-based scheduling algorithm can accommodate more systems as compared with the number of available transmission slots, while being efficient in terms of computational load and energy consumption. Simulation results show a significant reduction in energy expenditure in terms of decrease in duty cycle as compared with the periodic implementation. [ABSTRACT FROM AUTHOR]

Hub location problems have applications in a variety of fields including cargo delivery systems and telecommunication network design. Hub location problems deal with locating a set of hub nodes and allocating non-hub nodes to the located hubs. This paper presents a new bi-objective model for a multi-modal hub location problem under uncertainty considering congestion in the hubs. The objective functions attempt to minimize the total transportation cost as well as minimize the maximum transportation time between each pair of Origin-Destination (O-D) nodes in the network. To cope with the computational complexity of the problem, a well-known meta-heuristic algorithm, namely differential evolution (DE), is developed to obtain near-optimal Pareto solutions. Furthermore, several computational experiments and sensitivity analyses are provided to demonstrate the efficiency and applicability of the presented model and solution algorithm. Finally, the conclusion is presented. [ABSTRACT FROM AUTHOR]

Inter-datacenter networks (Inter-DCNs) and Intra-datacenter networks (Intra-DCNs) are entirely different in communication scales, architecture topologies and sizes, and characteristics of traffic flows. An Inter-DCN is built upon the existing Internet backbone with a fixed mesh topology and is hence difficult to accommodate any physical update or change without significant human intervention. Several core nodes of the backbone network are connecting to Intra-DCNs forming the so-called datacenter (DC) nodes. Different Inter-DCN or Intra-DCN architectures imply different network constructions overhead. An optimized combination of Inter-DCN and Intra-DCN architecture is expected to minimize the construction complexity and cost of DCNs while maintaining efficient network performance. However, research work in this important area has received little attention. In this paper, we study the construction of integrated Inter- and Intra- datacenter networks (integrated-DCN). Specifically, by taking advantages of different optical switching technologies and embedding the new control technology of software defined networking (SDN) in the control plane of integrated-DCN, novel cost-effective DCN architecture will be developed. For the proposed integrated architecture, the important characteristic of traffic asymmetry is investigated and accommodated by developing asymmetric network configuration based on SDN-assisted traffic monitoring/prediction, and the issue of network survivability/availability is explored and addressed by taking into consideration of the unique feature of DCN traffic. [ABSTRACT FROM AUTHOR]

There have been extensive works on the design of opportunistic spectrum access and routing schemes to improve spectrum efficiency in cognitive radio networks (CRNs), which becomes an integral component in the future communication regime. Nonetheless, the potentials of CRNs in boosting network performance yet remain to be explored to reach the full benefits of such a phenomenal technique. In this paper, we study the end-to-end latency in CRNs in order to find the sufficient and necessary conditions for real-time applications in finite networks and large-scale deployments. We first provide a general mobility framework which captures most characteristics of the existing mobility models and takes spatial heterogeneity into account. Under this general mobility framework, secondary users are mobile with an mobility radius $\alpha$ , which indicates how far a mobile node can reach in spatial domain. We find that there exists a cutoff point on $\alpha$ , below which the latency has a heavy tail and above which the tail of the latency is bounded by some Gamma distributions. As the network grows large, the latency is asymptotically scalable (linear) with respect to the dissemination distance (e.g., the number of hops or euclidean distance). An interesting observation is that although the density of primary users adversely impacts the expected latency, it makes no influence on the dichotomy of the latency tail in finite networks and the linearity of latency in large networks. Our results encourage CRN deployment for real-time and large applications, when the mobility radius of secondary users is large enough. [ABSTRACT FROM PUBLISHER]

In this article, we prove uniqueness results for coefficient inverse problems regarding wave, heat or Schrödinger equation on a tree-shaped network, as well as the corresponding stability result of the inverse problem for the wave equation. The objective is the determination of the potential on each edge of the network from the additional measurement of the solution at all but one external end points. Several results have already been obtained in this precise setting or in similar cases, and our main goal is to propose a unified and simpler method of proof of some of these results. The idea which we will develop for proving the uniqueness is to use a more traditional approach in coefficient inverse problems by Carleman estimates. Afterwards, using an observability estimate on the whole network, we apply a compactness–uniqueness argument and prove the stability for the wave inverse problem. [ABSTRACT FROM AUTHOR]

Several out-of-band mechanisms have been proposed as effective approaches for link fault localization in WDM networks, such as monitoring cycle, monitoring tree and monitoring trail. However, such technologies need extra resources, including dedicated supervisor lightpaths and monitors. On the contrary, an in-band mechanism called limited-perimeter vector matching fault localization protocol (LVM) is proposed to localize single link failure with low overhead using traffic lightpaths. Nevertheless, LVM leads to the high dependence of traffic lightpaths and the long fault localization time. In order to solve these issues, a fast fault localization mechanism based on Minimum Dominating Set Clustering (MDSC) is proposed in this paper. MDSC consists of two phases: the cluster allocation algorithm using minimum dominating set (CAM) and the fault localization algorithm based on clustering (FLC). According to CAM, the network is reasonably made up of a lot of clusters, and a sink node will then be selected. According to FLC, a failure can be effectively localized by a cluster headers or the sink node by collecting the status of traffic lightpaths. Theoretical analysis and simulation results demonstrate that the proposed mechanism can efficiently reduce the dependence on traffic lightpaths and optimize the speed of fault localization. [ABSTRACT FROM AUTHOR]

Energy is very important parameter during the creation of a WSN infrastructure, and to support long lifetimes, energyefficient operation is a key technique. Wireless sensor networks (WSNs) are known to be highly energy-constrained and each network's lifetime has a strong dependence on the node's battery capacity. As such, the network lifetime has been a critical concern in WSN research. While numerous energyefficient protocols have been proposed to prolong the network lifetime. Energy-efficient sensor state planning consists i finding an optimal assignment of states to sensors in order to maximize network lifetime. Network lifetime and energy consumption analysis for cluster-based wireless sensor networks based upon LEACH protocol for periodic monitoring applications induce unbalanced energy consumption among sensor nodes and hence affect the network lifetime when compared with the results obtained from the analytical model of this protocol. This highlights the need for an adaptive clustering protocol that can increase the network lifetime by further balancing the energy consumption among sensor nodes. [ABSTRACT FROM AUTHOR]

For billions of people, mobile phones have become essential communication means to produce and share multimedia contents. Most current sharing solutions rely on centralized online solutions, requiring a permanent Internet connectivity, with the conse- quence of increasing –and sometimes of overloading– the networks of mobile operators. This paper presents an anycast communication model allowing to offload data in wide intermittently-connected hybrid networks, using a peer-to-peer approach. Such networks combine an infrastructure part that relies on fixed equipments with intermittently or partially connected parts formed by mobile devices. This model has been implemented in a middleware platform called Nephila. Simulation results confirm that, with Nephila, thousands of people roaming a medium-size city center can share multimedia con- tents, using a combination of stable and transient transmission links. [ABSTRACT FROM AUTHOR]

According to a recent study, global IP traffic will have increased threefold over 2014 to 2018. This tremendous growth in IoT traffic and number of IoT devices, has given rise to new requirements from its infrastructure, such as for scalable content distribution,various QoS support, traffic management, security, trust, mobility and so forth. We are designing a context-basedNetwork Infrastructureto meet these requirements. We focus on context-aware in order to support user-centric IoT services. Also we consider multi-network access, mobility, access technologies, and security function. [ABSTRACT FROM AUTHOR]

Due the increasing number of published Semantic Web services (SWs) rendered the distributed discovery within repositories a critical issue and a major problem that can reduce the capability and functionality of SWs in terms of efficiency and scalability. Peer-to-Peer (P2P) computing is considered as the most dominant technology to discover new distributed and heterogeneous collaborative applications for SWs. In this paper, we propose an efficient approach for improving the performance and effectiveness of automatic and cooperative discovery of large-scale distributed systems in the unstructured P2P networks. The approach exploits a scalable epidemic algorithm that uses different sources of network knowledge, such as exponential distribution, to fulfill the users requirements in order to ensure high recall, further reduce the number of messages exchanged and reduce the execution time for discovering SWs in the unstructured P2P network. In order to improve the applicability of the scalable epidemic algorithm for discovering SWs, we propose the semantic matching of OWL-S process model which improves the recall while keeping an acceptable matching quality level. The experimental results show that our efficient approach is able dynamically to adapt to network changes and preserve high levels of recall. [ABSTRACT FROM AUTHOR]

In the past 15 years we have witnessed a tremendous increase in the usage of camera to capture videos. Cameras are widely used in surveillance of offices, malls, schools etc. The conventional architecture involves a cluster of cameras that communicate with a centralized server where all the processing is done. But as the network grew bigger the centralized network failed to show robustness. This instigated a need for a distributed camera network with optimized image processing algorithm to accommodate reduced computing. This paper outlines the concepts, architecture and application of this much needed distributed technology using the consensus algorithm. It also outlines the optimizations that need to be done in image processing inorder to compensate for the reduction in computing power at the nodes of the network. In this paper we also cite some recent research and outline its advantages over the traditional architecture. [ABSTRACT FROM AUTHOR]

This paper presents a design for a throughput-efficient online relay selection scheme for dual-hop multi-relay cooperative networks. Problems arise with these networks due to unpredictability of the relaying link quality and high time-consumption to probe the dual-hop link. In this paper, we firstly propose a novel probing and relaying protocol, which greatly reduces the overhead of the dual-hop link estimation by leveraging the wireless broadcasting nature of the network. We then formulate an opportunistic relay selection process for the online decision-making, which uses a tradeoff between obtaining more link information to establish better cooperative relaying and minimizing the time cost for dual-hop link estimation to achieve higher throughput. Dynamic programming is used to construct the throughput-optimal control policy for a typically heterogeneous Rayleigh fading environment, and determines which relay to probe and when to transmit the data. Additionally, we extend the main results to mixed Rayleigh/Rician link scenarios, i.e., where one side of the relaying link experiences Rayleigh fading while the other has Rician distribution. Numerical results validate the effectiveness and superiority of our proposed relaying scheme, e.g., it achieves at least 107% throughput gain compared with the state of the art solution. [ABSTRACT FROM AUTHOR]

Now a days, Efficient processing of Broadcast Queries is of critical importance with the ever-increasing deployment and use of mobile technologies. BQs have certain unique characteristics that the traditional spatial query processing in centralized databases does not address. In novel query processing technique, by maintaining high scalability and accuracy, latency is reduced considerably in answering BQs. Novel approach is based on peer-to-peer sharing, which enables us to process queries without delay at a mobile host by using query results cached in its neighboring mobile peers. We design and evaluate cooperative caching techniques to efficiently support data access in ad hoc networks. We first propose two schemes: Cache Data, which caches the data, and Cache Path, which caches the data path. After analyzing the performance of those two schemes, we propose a hybrid approach (Hybrid Cache), which can further improve the performance by taking advantage of Cache Data and Cache Path while avoiding their weaknesses. Cache replacement policies are also studied to further improve the performance. Simulation results show that the proposed schemes can significantly reduce the query delay and message complexity when compared to other caching schemes. [ABSTRACT FROM AUTHOR]

In this paper we study the network design game when the underlying network is a ring. In a network design game we have a set of players, each of them aims at connecting nodes in a network by installing links and equally sharing the cost of the installation with other users. The ring design game is the special case in which the potential links of the network form a ring. It is well known that in a ring design game the price of anarchy may be as large as the number of players. Our aim is to show that, despite the worst case, the ring design game always possesses good equilibria. In particular, we prove that the price of stability of the ring design game is at most 3/2, and such bound is tight. Moreover, we observe that the worst Nash equilibrium cannot cost more than 2 times the optimum if the price of stability is strictly larger than 1. We believe that our results might be useful for the analysis of more involved topologies of graphs, e.g., planar graphs. [ABSTRACT FROM AUTHOR]

In this paper, a cutting-plane neighborhood structure is proposed for the fixed-charge capacitated multicommodity network design (CMND) problem. In the proposed structure, different strategies are used to select an open arc in the incumbent solution to be closed. Then a linear programming (LP) model is generated on the basis of the modified incumbent solution by relaxing binary variables and adding new constraints. The generated LP solution is improved using different cutting-plane inequalities. Subsequently, a new sub-mixed integer programming (MIP) model is created by fixing a number of variables in the generated LP solution. Then the local branching algorithm is used to solve the sub-MIP model and its solution is considered as a neighboring solution. A tabu search algorithm is used to evaluate the proposed neighborhood structure. To tune the parameters of the tabu search algorithm, we have used the design of experiments method. Standard problems with different sizes are employed to evaluate the proposed tabu search algorithm. Results show the efficiency and effectiveness of the tabu search algorithm compared to the best methods found in the literature. [ABSTRACT FROM AUTHOR]