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The network-based mobility management is adapted to the OpenFlow architecture for mobility service at Software Defined Networking (SDN), and data structure for mobility service is proposed. SDN is a newly proposed Internet architecture which decouples the data and control planes, and mobility management is one of the most important issues in SDN. In order to provide mobility management service by utilizing the mobility scheme proposed earlier in a new network environment, the existing mobility schemes need to be modified. Particularly, the characters of the network environment need to be considered when designing the function of the network entities and data structure. Our proposed mobility management scheme is focused on the centralized control mechanism of SDN. We referred to Proxy Mobile IPv6 (PMIPv6) and OpenFlow-based PMIPv6 with a centralized mobility management controller (OPMIPv6-C). It has a merged data structure for the mobility service on SDN controller and minimizes the number of switches which need flow table modification at handover. At the performance analysis chapter, we compare the signaling cost at the registration and handover phase, packet delivery cost, and handover latency between the proposed scheme and OPMIPv6-C. [ABSTRACT FROM AUTHOR]

This paper focuses on the event-triggered zero-gradient-sum algorithms for a distributed convex optimization problem over directed networks. The communication process is driven by trigger conditions monitored by nodes. The proposed trigger conditions are decentralized and just depend on each node’s own state. In the continuous-time case, we propose an algorithm based on a sample-based monitoring scheme. In the discrete-time case, we propose a new event-triggered zero-gradient-sum algorithm which is suitable for more general network models. It is proved that two proposed event-triggered algorithms are exponentially convergent if the design parameters are chosen properly and the network topology is strongly connected and weight-balanced. Finally, we illustrate the advantages of the proposed algorithms by numerical simulation. [ABSTRACT FROM AUTHOR]

Privacy protection is the primary concern when RFID applications are deployed in our daily lives. Due to the computational power constraints of passive tags, non-encryption-based singulation protocols have been recently developed, in which wireless jamming is used. However, the existing private tag access protocols without shared secrets rely on impractical physical layer assumptions, and thus they are difficult to deploy. To tackle this issue, we first redesign the architecture of RFID system by dividing an RF reader into two different devices, an RF activator and a trusted shield device (TSD). Then, we propose a novel coding scheme, namely Random Flipping Random Jamming (RFRJ), to protect tags’ content. Unlike the past work, the proposed singulation protocol utilizes only the physical layer techniques that are already implemented. Analyses and simulation results validate our distributed architecture with the RFRJ coding scheme, which defends tags’ privacy against various adversaries including the random guessing attack, correlation attack, ghost-and-leech attack, and eavesdropping. [ABSTRACT FROM AUTHOR]

Proxy signature allows an original signer to delegate her signing capability to a proxy signer. Recently, to provide lower communication cost and stronger security, Zhang and Yu proposed a short proxy signature scheme in the standard model. They claimed that their scheme simultaneously achieves several merits including strong unforgeability, shorter signature length, and lower computational cost. However, we show that Zhang and Yu's scheme is not as secure as they claimed, because anyone can obtain the actual signing key of proxy signer from three valid proxy signatures. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A continuous finite-time control scheme for networked bilateral teleoperation is proposed in this brief. The terminal sliding mode technology is used and new master–slave torques are designed. With the new controller, the coordination error of the master manipulator and the slave manipulator converges to zero in finite time. Moreover, the reaching time and the sliding time can be derived. Finally, the comparisons are performed and simulations show the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

An x-star network is an information network which consists of centers with connections among themselves, and different type attributes linking to these centers. As x-star networks become ubiquitous, extracting knowledge from x-star networks has become an important task. Similarity search in x-star network aims to find the centers similar to a given query center, which has numerous applications including collaborative filtering, community mining and web search. Although existing methods yield promising similar results, such as SimRank and P-Rank, they are not applicable for massive x-star networks. In this paper, we propose a structural-based similarity measure, NetSim, towards efficiently computing similarity between centers in an x-star network. The similarity between attributes is computed in the pre-processing stage by the expected meeting probability over attribute network that is extracted from the whole structure of x-star network. The similarity between centers is computed online according to the attribute similarities based on the intuition that similar centers are linked with similar attributes. NetSim requires less time and space cost than existing methods since the scale of attribute network is significantly smaller than the whole x-star network. For supporting fast online query processing, we develop a pruning algorithm by building a pruning index, which prunes candidate centers that are not promising. Extensive experiments demonstrate the effectiveness and efficiency of our method through comparing with the state-of-the-art measures. [ABSTRACT FROM AUTHOR]

Computer generated holograms are often exploited to implement optical encryption schemes. This paper proposes the integration of dynamic visual cryptography (an optical technique based on the interplay of visual cryptography and time-averaging geometric moiré) with Gerchberg–Saxton algorithm. A stochastic moiré grating is used to embed the secret into a single cover image. The secret can be visually decoded by a naked eye if only the amplitude of harmonic oscillations corresponds to an accurately preselected value. The proposed visual image encryption scheme is based on computer generated holography, optical time-averaging moiré and principles of dynamic visual cryptography. Dynamic visual cryptography is used both for the initial encryption of the secret image and for the final decryption. Phase data of the encrypted image are computed by using Gerchberg–Saxton algorithm. The optical image is decrypted using the computationally reconstructed field of amplitudes. [ABSTRACT FROM AUTHOR]

Highlights: [•] An adaptive period sensing optimization scheme for cognitive radio is proposed. [•] Our scheme is based on a multi-objective genetic algorithm formulation. [•] We evaluated the sensing overhead, transmission opportunities and interference to PU. [•] Our scheme has a superior performance when compared to related literature. [•] It provides different levels of protection to PU communication. [ABSTRACT FROM AUTHOR]

Highlights: [•] We proposed prioritized proactive spectrum handoff decision schemes. [•] Proposed schemes are modeled using a preemptive resume priority (PRP) M/G/1 queue. [•] Handoff delay is reduced by the proposed schemes. [ABSTRACT FROM AUTHOR]

Telehaptics is the science of transmitting touch-related sensations over computer networks. With respect to robot teleoperation, telehaptics emphasizes more on reliably reproducing physical properties of a remote environment, as mediated over a network through the use of appropriate haptic interfacing technologies. One of the main factors that can cause degradation of the quality of a telehaptic system is the presence of time delays. Inspired by concepts such as impedance-reflection and model-mediated telemanipulation, an adaptive impedance control scheme has been proposed aiming to mitigate some of the problems caused by network delays in a telehaptic system. This paper presents an experimental analysis, which has been conducted to assess the actual performance of the proposed telehaptic scheme in terms of both control and human perception objectives. Firstly, a set of comparative numerical experiments is presented aiming to analyze stability and characterize transparency of the telehaptic system under large time delays. The results show the superior performance of the proposed adaptive impedance scheme as compared to direct force-reflecting teleoperation. Then, a series of psychophysical experiments is described, to evaluate the performance of the telehaptic system with respect to human perception of remote (delayed) stiffness. An analysis of the obtained results shows that the proposed adaptive scheme significantly improves telehaptic perception of linear stiffness in the presence of network delays, maintaining perceptual thresholds close to the ones obtained in the case of direct, nondelayed stimuli. A comparative experimental evaluation of psychometric transparency confirms the superior robustness with regard to time delay of the adaptive impedance telehaptic scheme as compared to state-of-the-art position/force transparentizing methods. [ABSTRACT FROM AUTHOR]

Highlights: [•] We introduce novel fault-tolerant architecture and efficient reconfiguration schemes. [•] We propose an efficient algorithm for producing maximum target arrays. [•] We develop an algorithm for optimizing communication performance of target arrays. [•] We provide an approach for calculating the theoretical maximum target array. [ABSTRACT FROM AUTHOR]

In this paper, we find a man-in-the-middle attack on the quantum signature scheme with a weak arbitrator (Luo et al., Int. J. Theor. Phys., 51:2135, ). In that scheme, the authors proposed a quantum signature based on quantum one way function which contains both verifying the signer phase and verifying the signed message phase. However, after our analysis we will show that Eve can adopt different strategies in respective phases to forge the signature without being detected. Then we present an improved scheme to increase the security. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, contention resolution scheme based on burst segmentation and deflection routing in the core node and composite burst assembly scheme at the edge node are proposed. In the core node, contention is resolved through incorporating prioritized burst segmentation with deflection routing scheme. The burst segmentation scheme allows the tail of original bursts or the head of contending bursts to be segmented. The segmented burst is scheduled on the optimum deflection path by deflection routing scheme. At the edge of the network, a composite burst assembly scheme combines packets of different classes into the same burst, placing the highest priority packets in the middle and low priority packets at the tail and the head of the burst. The priority lowers gradually from the middle of the burst to the ends. An analytical model is proposed to evaluate the contention resolution scheme through calculating packet loss probability and the normalized end-to-end delay. Results show that high-priority bursts have significantly lower packet loss probability and delay than low-priority. So the contention resolution scheme which incorporates burst segmentation with deflection routing tends to perform better than the scheme only with burst segmentation or deflection routing. [Copyright &y& Elsevier]

Recent studies on change detection for RDF data have focused on minimizing the delta size and, as a way to exploit the semantics of RDF models in reducing the delta size, the forward-chaining inferences have been widely employed. However, since the forward-chaining inferences should pre-compute the entire closure of the RDF model, the existing approaches are not scalable to large RDF data sets. In this paper, we propose a scalable change detection scheme for RDF data, which is based on backward-chaining inference and pruning. Our scheme, instead of pre-computing the full closure, computes only the necessary closure on the fly, thus achieving fast and scalable change detection. In addition, for any two RDF data input files to be compared, the delta obtained from our scheme is always equivalent to the one from the existing forward-chaining inferences. In addition, in order to handle RDF data sets too large to fit in the available RAM, we present an SQL-based implementation of our scheme. Our experimental results show that our scheme, in comparison to the existing schemes, can reduce the number of inference triples for RDF change detection by 10–60%. [ABSTRACT FROM PUBLISHER]

This paper proposes an efficient hybrid modulation scheme for a mixed phase-shift keying and pulse-position modulation (PSK/PPM) for heterogeneous networks employing ultra-wideband impulse radio (UWB-IR). The proposed scheme can support both coherent and noncoherent reception and is compatible with the IEEE 802.15.4a standard. Conventional hybrid modulation schemes for heterogeneous networks are generally constructed with a super-orthogonal coding (SOC) technique with which coherent receivers can get an additional performance improvement by encoding the phase bits. However, with the proposed modulation scheme, a coherent receiver can achieve a performance improvement by displaying its best capability on phase detection through a simple waveform mapping scheme. The proposed scheme requires no extra hardware or power consumption for performance improvement in coherent receivers. Simulations show that the BER of the proposed scheme in a coherent receiver is increased by 2.7dB over the hybrid modulation with no combined phase coding and also comparable to the SOC-combined modulation scheme employed in the IEEEE 802.15.4a. The error performance of the proposed scheme is analyzed, and the numerical results are presented in this paper. [ABSTRACT FROM AUTHOR]

Link failure localization has been an important and challenging problem for all-optical networks. The most general monitoring structure, called m-trail, is a light-path into which optical signals are launched and monitored. How to minimize the number of required m-trails is critical to the expense of this technique. Existing solutions are limited to localizing single link failure or handling only small networks. Moreover, some practical constraints, like lacking of knowledge of the failure quantity, are ignored. To overcome these limitations is prospective but quite challenging. To this end, we provide novel theoretical solution frameworks toward the multi-failure localization problem. On one hand, for small dense networks, we provide a tree-decomposition based algorithm; on the other hand, a random walk based localized algorithm for large scale sparse networks is proposed. In addition, we further adapt these two algorithms to cope with three practical constraints. Theoretical analysis and simulation results are included to prove the correctness and efficiency of the proposed schemes. [ABSTRACT FROM AUTHOR]

There is a growing interest in energy efficient or so-called "green" wireless communication to reduce the energy consumption in cellular networks. Since today's wireless terminals are typically equipped with multiple network access interfaces such as Bluetooth, Wi-Fi, and cellular networks, this paper investigates user terminals cooperating with each other in transmitting their data packets to the base station (BS), by exploiting the multiple network access interfaces, called inter-network cooperation. We also examine the conventional schemes without user cooperation and with intra-network cooperation for comparison. Given target outage probability and data rate requirements, we analyze the energy consumption of conventional schemes as compared to the proposed inter-network cooperation by taking into account both physical-layer channel impairments and upper-layer protocol overheads. It is shown that distances between different network entities (i.e., user terminals and BS) have a significant influence on the energy efficiency of proposed inter-network cooperation scheme. Specifically, when the cooperating users are close to BS or the users are far away from each other, the inter-network cooperation may consume more energy than conventional schemes without user cooperation or with intra-network cooperation. However, as the cooperating users move away from BS and the inter-user distance is not too large, the inter-network cooperation significantly reduces the energy consumption over conventional schemes. [ABSTRACT FROM AUTHOR]

We investigate efficient communication over multiple-input multiple-output (MIMO) two-way relay channels (TWRCs), where two multi-antenna users exchange information via a multi-antenna relay. We propose a new MIMO physical-layer network coding (PNC) scheme that includes novel eigen-direction alignment (EDA) precoding. The proposed EDA precoding efficiently aligns the two-user's eigen-modes into the same set of orthogonal directions, and multiple independent PNC streams are implemented over the aligned eigen-modes. We derive an achievable rate-pair of the proposed scheme, for given EDA precoding parameters, over a MIMO TWRC. To maximize the achievable rate-region, we formulate a design criterion for the EDA precoding parameters, and present solutions to the formulation. Closed-form bounds on the sum-rates of the designed EDA-PNC schemes are derived. Numerical results show that there is only a small gap between the achievable rate of the proposed scheme and the capacity upper bound of the MIMO TWRC. It is shown that the proposed scheme can significantly outperforms existing schemes in the literature. [ABSTRACT FROM PUBLISHER]

This paper studies relay selection schemes for two-way amplify-and-forward (AF) relay networks. For a network with two users that exchange information via multiple AF relays, we first consider a single-relay selection (SRS) scheme based on the maximization of the worse signal-to-noise ratio (SNR) of the two end users. The cumulative distribution function (CDF) of the worse SNR of the two users and its approximations are obtained, based on which the block error rate (BLER), the diversity order, the outage probability, and the sum-rate of the two-way network are derived. Then, with the help of a relay ordering, a multiple-relay selection (MRS) scheme is developed. The training overhead and feedback requirement for the implementation of the relay selection schemes are discussed. Numerical and simulation results are provided to corroborate the analytical results. [ABSTRACT FROM AUTHOR]

Due to the advancement of network technology, video-on-demand (VoD) services are growing in popularity. However, individual stream allocation for client requests easily causes a VoD system overload; when its network and disk bandwidth cannot match client growth. This study thus presents a fundamentally different approach by focusing solely on a class of applications identified as latency tolerant applications. Because video broadcasting does not provide interactive (i.e., VCR) functions, a client is able to tolerate playback latency froma video server. One efficient broadcasting method is periodic broadcasting, which divides a video into smaller segments and broadcasts these segments periodically on multiple channels. However, numerous practical systems, such as digital video broadcasting-handheld (DVB-H), do not allow clients to download video data frommultiple channels because clients usually only have one tuner. To resolve this problem in multiple-channel broadcasting, this study proposes a novel single-channel broadcasting scheme, which leverages segment-broadcasting capability further for more efficient video delivery. The comparison results show that, with the same settings of broadcasting bandwidth, the proposed scheme outperforms the alternative broadcasting scheme, the hopping insertion scheme, SingBroad, PAS, and the reverse-order scheduling scheme for the maximal waiting time. [ABSTRACT FROM AUTHOR]

The correctness of logic programs which are constructed by a schema-based method is presented in this paper. This schema-based method constructs typed, moded logic programs by stepwise top-down design using five program schemata, data types and modes. Correctness proofs in this approach are guided by the constructed logic programs. A proof scheme is proposed for each program schema. It is claimed that the structure of a logic program constructed by this schema-based method is reflected in the structure of its correctness proof. The proof schemes which correspond to design schemata are followed in the correctness proofs of logic programs. [ABSTRACT FROM AUTHOR]

The study develops algorithmic enhancements to a commercially operating self-learning fingerprinting algorithm, to fully exploit single-leg time measurements. Such timing advance (TA) and round trip time (RTT) measurements are available in all cellular systems. Their accuracies do not depend on the cell size, as do conventional signal strength measurements, which makes such time measurements particularly useful for positioning in large cells. The challenge is that the geographical regions associated with single-leg time measurements become curved and very wide laterally, while staying narrow in the radial direction, a fact which makes it difficult for the self-learning algorithm to compute accurate geographical descriptions of them. The study shows how to design enhanced algorithms that improve the accuracy and reduce the learning time of the fingerprinting positioning scheme. The performance gain is illustrated with simulations. It is also illustrated by simulation that the enhanced fingerprinting scheme can handle very poor base station geometries that would prevent the application of conventional trilatheration-based localisation technologies. This typically occurs along freeways in rural regions, where so called 'string of pearls' geometries are common. [ABSTRACT FROM AUTHOR]

Realizing application systems that match people's expectations and providing adequate network services for various users under various network and platform environments are difficult challenges. To overcome these problems, we have studied application systems based on multiagent systems and design models of multiagent systems. We propose a method to observe and control the behavioral characteristics of multiagent systems to support the design, development, and operation of such systems. More specifically, we propose a Flexible Distributed System and a Behavioral Characteristics Model, and we apply these two models to the design of an actual multimedia communication system and evaluate the effectiveness of the proposed scheme. [ABSTRACT FROM AUTHOR]

By examining the diversity-multiplexing tradeoff (DMT) of an amplify-and-forward (AF) multi-antenna multi-relay network, a procedure to select the optimal number of relays and relay candidates is established. Subsequently, a distributed BLAST transmission scheme in conjunction with successive nulling and cancellation at destination is proposed to achieve the optimal DMT. Illustrative results indicate that the proposed method can significantly enhance the outage probability performance, and for a selected number of relays in use, the performance enhancement can be further improved by increasing the number of available relays in the AF network. Copyright © 2010 John Wiley & Sons, Ltd. A distributed BLAST transmission scheme in conjunction with successive nulling and cancellation at destination is proposed to achieve the optimal DMT. Illustrative results indicate that the proposed method can significantly enhance the outage probability performance, and for a selected number of relays in use, the performance enhancement can be further improved by increasing the number of available relays in the amplify-and-forward (AF) network. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: Dynamic balancing of computation and communication load is vital for the execution stability and performance of distributed, parallel simulations deployed on the shared, unreliable resources of large-scale environments. High Level Architecture (HLA) based simulations can experience a decrease in performance due to imbalances that are produced initially and/or during run time. These imbalances are generated by the dynamic load changes of distributed simulations or by unknown, non-managed background processes resulting from the non-dedication of shared resources. Due to the dynamic execution characteristics of elements that compose distributed applications, the computational load and interaction dependencies of each simulation entity change during run time. These dynamic changes lead to an irregular load and communication distribution, which increases overhead of resources and latencies. A static partitioning of load is limited to deterministic applications and is incapable of predicting the dynamic changes caused by distributed applications or by external background processes. Therefore, a scheme for balancing the communication and computational load during the execution of distributed simulations is devised in a scalable hierarchical architecture. The proposed balancing system employs local and cluster monitoring mechanisms in order to observe the distributed load changes and identify imbalances, repartitioning policies to determine a distribution of load and minimize imbalances. A migration technique is also employed by this proposed balancing system to perform reliable and low-latency load transfers. Such a system successfully improves the use of shared resources and increases distributed simulations’ performance by minimizing communication latencies and partitioning the load evenly. Experiments and comparative analyses were conducted in order to identify the gains that the proposed balancing scheme provides to large-scale distributed simulations. [ABSTRACT FROM AUTHOR]

Delay-tolerant networks (DTNs) provide a promising solution to support wide-ranging applications in the regions where end-to-end network connectivity is not available. In -DTNs, the intermediate nodes on a communication path are expected to store, carry, and forward the in-transit messages (or bundles) in an opportunistic way, which is called opportunistic data forwarding. Such a forwarding niethod depends on the hypothesis that each individual node is ready to forward packets for others. This assumption, however, might easily be violated due to the existence of selfish or even malicious nodes, which may be unwilling to waste their precious wireless resources to serve as bundle relays. To address this problem, we propose a secure multilayer credit-based incentive scheme to stimulate bundle forwarding cooperation among DTN nodes. The proposed scheme can be implemented in a fully distributed manner to thwart various attacks without relying on any tamperproof hardware. In addition, we introduce several efficiency optimization techniques to improve the overall efficiency by exploiting the unique characteristics of DTNs. Extensive simulations demonstrate the efficacy and efficiency of the proposed scheme. [ABSTRACT FROM AUTHOR]

This article provides an overview of some of the optical grooming (aggregation) techniques that have been developed recently with IP as the client layer. We identify four kinds of aggrega- tion strategies: point to point (P2P), point to multipoint (P2MP), multipoint to point (MP2P), and multipoint to multipoint (MP2MP). Using an auxiliary graph-based model, we evaluate the performance of these four strategies for single- hop and multihop scenarios that aggregate at the path level. In the case of partial mesh networks with dynamic traffic, we observe the following: MP2MP outperforms other architectures by mul- tiple orders of magnitude in single-hop scenar- ios; P2P performs best in multihop transceiver-constrained scenarios; and P2MP performs the best in multihop wavelength-con- strained scenarios. [ABSTRACT FROM AUTHOR]

Boolean networks and their dynamics are of great interest as abstract modeling schemes in various disciplines, ranging from biology to computer science. Whereas parallel update schemes have been studied extensively in past years, the level of understanding of asynchronous updates schemes is still very poor. In this paper we study the propagation of external information given by regulatory input variables into a random Boolean network. We compute both analytically and numerically the time evolution and the asymptotic behavior of this propagation of external regulation (PER). In particular, this allows us to identify variables that are completely determined by this external information. All those variables in the network that are not directly fixed by PER form a core which contains, in particular, all nontrivial feedback loops. We design a message-passing approach allowing to characterize the statistical properties of these cores in dependence of the Boolean network and the external condition. At the end we establish a link between PER dynamics and the full random asynchronous dynamics of a Boolean network. [ABSTRACT FROM AUTHOR]

Although random access operations are desirable for on-demand video streaming in peer-to-peer systems, they are difficult to efficiently achieve due to the asynchronous interactive behaviors of users and the dynamic nature of peers. In this paper, we propose a network coding equivalent content distribution (NCECD) scheme to efficiently handle interactive video-on-demand (VoD) operations in peer-to-peer systems. In NCECD, videos are divided into segments that are then further divided into blocks. These blocks are encoded into independent blocks that are distributed to different peers for local storage. With NCECD, a new client only needs to connect to a sufficient number of parent peers to be able to view the whole video and rarely needs to find new parents when performing random access operations. In most existing methods, a new client must search for parent peers containing specific segments; however, NCECD uses the properties of network coding to cache equivalent content in peers, so that one can pick any parent without additional searches. Experimental results show that the proposed scheme achieves low startup and jump searching delays and requires fewer server resources. In addition, we present the analysis of system parameters to achieve reasonable block loss rates for the proposed scheme. [ABSTRACT FROM PUBLISHER]