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The interaction of intelligent agents implies the existence of an environment to support it. The usual representations of this environment are graphs with certain properties. Throughput is one of the most important characteristics of such graphs. A traditional metric, such as the usual shortest paths, forms the basis of the traditional throughput index. In this case, a metric is used to synthesize the distribution of multi-coloured flows in graphs more complex than trees. To achieve better results than when using ordinary shortest paths, one can use the Euclidian metric. Working with weighted graphs requires a generalization of the explicit form of the Moore-Penrose pseudo inversed incidence matrix. The validity of the generalization is confirmed by verification of the Penrose conditions. An example of using the Euclidian metric for the distribution of computer network flows is given. [ABSTRACT FROM AUTHOR]

Abstract The purpose of this paper is to solve the problem of low recognition accuracy of three-degree-of-freedom myoelectric prosthesis and long training time.According to the nonstationarity of the EMG signal, the wavelet packet is used to decompose the EMG signal and the energy and variance of the wavelet packet coefficients of the four-channel EMG signal are extracted as feature vectors.Then Particle Swarm Optimization(PSO) was combined with improved support vector machine(ISVM) to construct a new model(PSO-ISVM). Under the premise of ensuring the sparseness of the SVM, the slack variables and the decision function was improved to reduce the constraint conditions for solving the optimal face in the quadratic programming. SVM is optimized by the PSO in order to improve the accuracy of the model.The experimental results show that the improved algorithm can effectively identify six kinds of commonly used upper limb movements compared with the traditional SVM. The average recognition rate reaches 90.66% and training time can be shortened 0.042 s. [ABSTRACT FROM AUTHOR]

Abstract The rapid growth of packet based Internet traffic and big data, associated with interconnected Data Centers (DC) and High Performance Computing (HPC) systems have imposed the need for ultrahigh link capacities and ultrahigh packet switching speeds, at network nodes. In order to overcome these ultrahigh demands, and particularly packet routing and forwarding, All Optical Label Swapping (AOLS) has been considered for many years as an established solution. This survey paper gives an updated and thorough investigation on AOLS technology and trends, based on a vast reference amount of research milestones throughout all this long time era. All types of labeling techniques are presented and compared, and their pros and cons are summarized all together. Moreover, important issues and directions for research are discussed, giving researchers guidelines and motivation for extended investigation. [ABSTRACT FROM AUTHOR]

In this paper, the problem of finite-time state estimation for delayed periodic neural networks over multiple-packet transmission is addressed. The components of measurement output are separately transmitted by multiple-packet transmission, and the randomly occurring packet dropouts of different channels are described by mutually independent Bernoulli processes. In order to improve the robustness of the estimator, a non-fragile estimator is designed. In addition, some sufficient criteria are given to ensure that the estimation error system is stochastically finite-time stable and stochastically finite-time bounded, and the gains of non-fragile estimator are then derived based on these results. Finally, simulation results are provided to illustrate the effectiveness of the proposed estimator design approach. [ABSTRACT FROM AUTHOR]

We consider networked control systems (NCSs) composed of a linear plant and a linear controller interconnected by packet-based communication channels with communication constraints. We are interested in the setup where direct-feedthrough terms are present in the plant and/or in the controller, a case that is largely ignored in the literature due to its inherent complexity and counterintuitive results in the analysis despite its relevance for important classes of controllers including Proportional–Integral (PI) regulators. This setup calls for a novel stability analysis, for which we take a renewed look at the concept of uniformly globally exponentially stable (UGES) scheduling protocols that turned out to be instrumental in earlier approaches. We provide a generalization of the UGES property, called ( D P , D C ) -UGES with D P ∕ D C being the direct-feedthrough matrices of the plant/controller, respectively, and we present generic conditions on these direct-feedthrough terms D P ∕ D C such that the classical UGES property of scheduling protocols implies ( D P , D C ) -UGES. This allows us to derive conditions leading to a maximally allowable transmission interval (MATI) such that stability of the overall NCS is guaranteed. In addition, it is shown that it is possible to get more tailored results for the well-known sampled-data (SD), round-robin (RR), and try-once-discard (TOD) protocols leading to less conservative conditions on the direct-feedthrough terms than the generic ones. We also introduce new ( D P , D C ) -UGES scheduling protocols, designed to handle the direct-feedthrough terms in a more effective way than existing protocols. Our results are illustrated using the example of a batch reactor. [ABSTRACT FROM AUTHOR]

This paper studies the problem of determining sensor locations in a large sensor network using only relative distance (range) measurement. Based on the barycentric coordinate representation, we propose a totally asynchronous distributed algorithm under DILOC framework due to independence of sensor update instants and unreliable networks with communication delays and packet losses. Through modeling the asynchronous algorithm as a linear difference equation with time-varying delays, we prove that the location estimates of sensors are globally convergent to the true coordinates if: (1) time interval between any two consecutive update instants is bounded from below and above, (2) communication delays and successive packet losses between sensors are finite. Simulation examples are provided to demonstrate the effectiveness of the theoretical result. [ABSTRACT FROM AUTHOR]

An Optical Bust Switching (OBS) network is vulnerable to a range of issues. One of the most significant issues is Burst Header Packet (BHP) flooding attacks, which can negatively impact on the Quality of Service (QoS) and create more urgent issues such as Denial of Service (DoS). Existing techniques for countering BHP flood attacks usually display a low accuracy in detecting misbehaving nodes leading to BHP attacks. By contrast, Machine Learning (ML) is a widely adopted and powerful data analysis technique which has showed a high degree of predictive performance in multiple application domains due to its ability to discover beneficial knowledge for decision-making. This study investigates the use of predictive ML to counter the risk of BHP flooding attacks experienced in OBS networks, proposing a decision tree-based architecture as an appropriate solution. This contains a learning algorithm that extracts novel rules from tree models using data processed from several simulation runs. The results show that the rules derived from our learning algorithm will accurately classify 93% of the BHP flooding attacks into either Behaving (B) or Misbehaving (M) classes. Moreover, the rules can further classify the Misbehaving edge nodes into four sub-class labels with 87% accuracy, including: Misbehaving-Block (Block), Behaving-No Block (No Block), Misbehaving-No Block (M-No Block), and Misbehaving-Wait (M-Wait). The results clearly show that our proposed decision tree model is a viable solution compared to decisions undertaken by expert domains or human network administrators. [ABSTRACT FROM AUTHOR]

It has been shown that the maximum distance routing strategy which works well on a Unit Disk Graph (UDG), performs poorly when it is executed on a Non Unit Disk Graph (N-UDG) which reflects the radio irregularity phenomenon. This latter arises from multiple factors, such as antenna and medium type, and is accentuated by environmental factors such as obstacles (e.g., buildings, hills, mountains) and weather conditions. In this paper, we propose a Cross-Layer Greedy Routing algorithm (CL-GR) which enables a correct position-based routing on a N-UDG. It provides two novel greedy routing strategies, termed respectively, Progress towards the sink node through Symmetrical links that experience the lowest Path Loss (PSPL) and progress through symmetrical links, combining the Maximum Distance forwarding strategy and the PSPL (MDPSPL). We compare our CL-GR to an Enhanced version of the Greedy algorithm of the Greedy Perimeter Stateless Routing protocol (GPSR), that we call E-GR and which can be executed on a N-UDG, and to COP _ GARE algorithm. The simulation results show that both PSPL and MDPSPL enable higher Packet Delivery Ratio (PDR) and energy efficiency. In terms of end-to-end delay, while the PSPL strategy significantly increases this metric, the MDPSPL strategy enables a satisfactory end-to-end delay, comparatively to E-GR and COP _ GARE. [ABSTRACT FROM AUTHOR]

For the practical deployment of optical packet switching (OPS) system, realizing all-optical buffering is a critical issue. In this paper, we present a hybrid labelling scheme based on optical code-division multiplexing (OCDM) over generalized multi-protocol label switching (GMPLS) network. The virtual optical memory is implemented by assigning queuing packets with different coded-WDM labels. The proposed hybrid labels combine the advantages of wavelength-division multiplexing (WDM) with spectral-amplitude-coding (SAC) OCDM. Due to the cyclic-shift property of arrayed-waveguide grating (AWG) and maximal-length sequence (M-sequence) codes, blocks of label generating and processing in node organization can be built in low complexity. Furthermore, utilizing hybrid coding technique in the buffering node increases the efficiency of label generating and processing. Derivation of the probability of packet missing is done to quantify the buffering performance of virtual optical memory. Simulation results show that the hybrid-coded labels, as compared to the conventional OCDM labels, are able to buffer the data packets with a relatively low probability of packet missing under similar label length. [ABSTRACT FROM AUTHOR]

Wireless Sensor Networks nowadays find wide variety of applications especially in real time. Innovative methods of energy efficient protocols and transmission reduction techniques keep improving to enhance the lifetime of the sensor nodes as they are powered by non-rechargeable batteries. Multi hop transmission and data aggregation are major techniques to reduce the power spent by the sensor node. In this paper, we propose a new ribbon structure for the existing multi hop WSN topologies with modified media access control mechanism called co-operative MAC. The ribbon structure is proposed to reap benefits of PEGASIS and APTEEN protocols. The low power consumption as in PEGASIS is maintained but the number of data packets transmitted is reduced by half. In the proposed scheme, only one of the two nodes along the parallel path involves in data transmission alternating roles in every cycle of aggregation. However, for values sensed above threshold, the inactive node interferes with normal cycle and gets its data transmitted to the sink node. This algorithm is compared with cluster based and chain based protocols and the simulation results show significant energy savings. [ABSTRACT FROM AUTHOR]

Quality of group communication using mobile ad-hoc networks depends on various factors like channel fading, signal quality, path loss, transmission and reception power of mobile nodes, mobility, link life and battery backup. Different layers are involved in communication, but the behavior of these layers is isolated with each other and overall network performance may effect from their operations. A cross-layer approach can extract the critical information from multiple layers which can be further utilized to enhance the overall network performance and Quality of Service (QoS). In this paper, Cross-layer Multicast Routing (CLMR) is introduced to enhance the QoS using a tree-based multicast routing protocol. In order to achieve QoS, optimization of the tree operations and tree management cost has been done. CLMR exploits the functionality of PHY layer, Application layer and Routing Layer for QoS oriented communication. Performance of CLMR is analyzed using Multicast Ad-Hoc On-Demand Distance Vector (MAODV) routing protocol under various parameters, i.e. Throughput, Delay, Packet Delivery Ratio, Link Cost and Energy Consumption. [ABSTRACT FROM AUTHOR]

There are two major issues in spatial crowdsourcing: travel route optimization and control policies. To address the two issues above, we introduce the concept of Pocket switch network (PSN) into the CD-system. First, we formulate a generalized optimization problem into three aspects of connectivity, profit and risk, motivated by the concepts in PSN. Afterward, these three aspects are mathematically described and optimized by a routing algorithm based on dynamic mobility and social graph. This algorithm consists of two parts: social graph extraction and social mobility based routing. Social graph learns the social knowledge of each patrician while social mobility based routing decides the leaving nodes of the passages according to their social graph. Finally, we evaluated the effectiveness and robustness of the proposed method on the realistic traces. The results demonstrated its superior performance in connectivity, profit, and risk. [ABSTRACT FROM AUTHOR]

Cognitive Radio (CR) technology is an agile solution for spectrum congestion and spectrum access utilization problems that result from the legacy fixed spectrum management policies. CR technology can exploit unused licensed band to meet the increasing demand for radio frequency. The routing process faces many challenges in CR Network (CRN) such as the absence of centralized infrastructure, the coordination between the routing module and spectrum management module, in addition to the frequent link failure due to the sudden appearance of PUs. In this paper we propose a Tree routing protocol for cognitive radio network (C-TRP) that jointly utilizes the tree routing algorithm with a spectrum management module in routing decisions, and also we proposed a new metric used in taking the best route decisions. In addition, we enhance the traditional tree routing algorithm by using a neighbor table technique that speeds up the forwarding data packets. Moreover, we add a robust recovery module to C-TRP to resume the network in case of the link failure. The main motivation in the design of C-TRP is quick data transmission and maximization of date rates. The performance evaluation is carried out in NS2 simulator. The simulation results proved that C-TRP protocol achieves better performance in terms of average “PDR”, “end-to-end delay” and “routing overhead ratio “compared to “CTBR” and “STOD-RP” routing protocols. [ABSTRACT FROM AUTHOR]

Software Defined Networks (SDN) is a novel model for networking that is currently becoming an interesting area for research and industry organizations which makes networks more manageable and customizable. In this paper, we investigated OpenFlow Discovery Protocol v.2 (OFDP v2) and compare it with standard OFDP protocol. We also intend to study OFDP v2 behavior and how it works in term of packet retransmission between SDN controller and SDN switches. We mean to show how OFDP v2 works from different perspective. Our experiments show that using OFDPv.2B protocol requires at least one retransmission per each packet which the controller sends out. However, OFDPv.2 still shows better results when it is compared with standard OFDP protocol in term of reducing the number of Packet_OUT messages. [ABSTRACT FROM AUTHOR]

The paper presents a study of key aspects in the design of a flexible unified data plane capable of integrating both fronthaul and backhaul transport in future 5G systems. In this study, we first review candidate access and multiplexing technologies from the state of the art and assess their capability to support legacy and new fronthaul and backhaul traffic. We then propose a new design framework for the targeted flexible unified data plane, featuring a primary packet-switching path supported by an auxiliary circuit-switching for extreme low latency scenarios. This comprises a summary of the first results achieved in the 5G-Crosshaul EU project since its kick-off in July 2015. [ABSTRACT FROM AUTHOR]

This paper addresses the distributed fusion filtering problem for discrete-time random signals from measured outputs perturbed by random parameter matrices and correlated additive noises. These measurements are obtained by a sensor network with a given topology, where random packet dropouts occur during the data transmission through the different network communication channels. The distributed fusion estimation is accomplished in two phases. Firstly, by an innovation approach and using the last observation that successfully arrived if a packet is lost, a preliminary distributed least-squares estimator is designed at each sensor node using its own measurements and those from its neighbors. Secondly, every sensor collects the preliminary filters that are successfully received from its neighbors and fuses this information with its own one to generate the least-squares linear matrix-weighted distributed fusion estimator. The accuracy of the proposed estimators, which is measured by the estimation error covariances, is examined by a numerical simulation example. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of the performance of transmit antenna selection in multiple-input multiple-output (MIMO) systems with N Stop and Wait (N-SAW) at the data link layer. The impact of packet size, number of SAW processes and the stalling of packets inside the receiver reordering buffer, due to N-SAW, on transmit antenna selection is investigated. Antenna selection is implemented as a signal processing technique that enhances the performance of the MIMO system; two schemes, throughput and capacity based transmit antenna selection are considered. Results show that under similar conditions, throughput maximization outperforms capacity maximization in terms of throughput, transmission latency and dropped packets when stall avoidance is implemented. The results further show that throughput and dropped packets increase with increase in SAW processes and decrease with increase in packet size. Transmission latency increases with increase in packet size and remains unchanged with increase in number of SAW processes. [ABSTRACT FROM AUTHOR]

Recently, high port-count optical packet switches, based on the Arrayed Waveguide Grating (AWG) device, have been proposed for providing the very high bandwidth and connectivity degree that will be required in future datacentre interconnection networks. A practical, cost-effective realisation of such a switch requires that over-subscription of the AWG cross-connect output ports be allowed, with the resulting packet contention being resolved using a packet buffering facility in the switch. In this paper, we propose an efficient AWG switch architecture of this type that uses a recirculating optical packet buffering scheme and we develop analytic modelling methods to estimate the switch packet blocking probability and packet buffering delay. The analytic model resolves internal traffic flows in the switch as Markov-modulated Poisson Processes (MMPP) and also allows modelling of offered load to the switch as a MMPP process. Taking this model of the switch, we first show its accuracy compared to discrete event simulations and then use it to develop a heuristic optimisation algorithm to dimension the switch hardware components, with the objective of minimising the operating cost by optimally dimensioning the main power consuming components, subject to constraints on the maximum contention probability and average and maximum propagation delays. The resulting optimised switch design demonstrates the proposed architecture to be a promising candidate for future high-port count datacentre switches. [ABSTRACT FROM AUTHOR]

Optical packet switching provides high-speed and energy-efficient packet forwarding. Fiber delay line (FDL)-based buffer is one practical solution to avoid packet contention in optical packet switches. However, the FDL buffer suffers from scalability problems, and thus, cannot accommodate a large volume of network traffic at a time. An optical and electronic combined (OE) buffer architecture alleviates the scalability issues. This architecture uses supplementary electronic RAM buffers when the traffic volume increases. We then propose an analytical model of the OE buffer to estimate the blocking probability and the average delay. We find that complex OE combined model can be simply modeled by combination of an existing analytic model of the FDL buffer and an M / M /1/ K queueing system. Comparing analytical results with packet-level simulation results, we demonstrate that our analytical results display characteristics similar to the simulation results. This analysis enables to determine appropriate setting of the OE buffer such as the buffer size and use policy. [ABSTRACT FROM AUTHOR]

IPv6 is the next generation internet protocol which will eventually replace IPv4, but till then both the protocols need to coexist for a long time. The main issue is of compatibility; both the protocols are not compatible with each other. A different set of routing protocols is required for IPv4 and IPv6. These protocols have different performances for different scenarios. Routing is a very challenging task especially in case of wireless networks. In this paper the performance is evaluated for different routing protocols like RIP, RIPng, OSPFv2 and OSPFv3 for IPv4 and IPv6 networks over Mobile Adhoc Networks. Simulations are carried out on Exata Cyber 1.1 Simulator. The performance of networks is measured on the basis of following parameters: throughput, end-to-end delay, jitter and packet delivery ratio with varying packet sizes of 256, 512, 1024 and 2058 bytes. [ABSTRACT FROM AUTHOR]

Mobile Ad hoc network is a self organized, self maintained network. Node movement is the important factor of increasing the control overhead in the network. The main objective of the paper is to reduce the control overhead by using the domination set based routing. The nodes which use to connect all the other nodes in the network are called dominating nodes, and the set of dominating nodes forms domination set. This paper proposes a new approach for finding the route and reducing the reroute establishment delay and increasing the packet delivery ratio. The efficiency of the method is demonstrated through simulation study. [ABSTRACT FROM AUTHOR]

In the present paper, we discuss the stabilization and controllability issues of the hybrid switching and impulsive higher order Boolean networks. First, the hybrid switching and impulsive controller is introduced. Second, the algebraic form of the system is given. Third, sufficient and necessary conditions for the stabilization and controllability of the system are presented, respectively. At last, an illustrative example shows the effectiveness of the main results. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new method for multi-damage extraction and classification of gear system is proposed. [•] Using PCA and KPCA to extracte the signal feature of gear system. [•] Five kinds of fault signal are analyzed under 300rpm, 900rpm, 1200rpm and 1500rpm. [•] Proposed method can be used to identify various faults (multi-fault) and damage level. [Copyright &y& Elsevier]

Abstract: Optical Label Switching (OLS) has been considered to be a promising approach to realize optical packet switching (OPS) networks. In an OLS router, the header processing module retrieves the routing information carried in the optical header and then replaces the old header with a new one through optical label swapping. The cost-effectiveness and the speed of performing label swapping are two major concerns. Due to lack of optical random access memory, optical label swapping has become a big challenging issue in implementing OLS switches. To overcome these difficulties, in this paper, we propose two Linear Random Code (LRC)-based label encoding schemes to achieve label swapping free OPS networks. Using the proposed schemes, a small sized label is needed. Only simple modulo-2 multiplication and modulo-2 addition operations are required to decode an optical label and there is no optical label swapping during packets traverse along the entire routing path. In our system, each source–destination pair is assigned multiple paths so the network is with traffic engineering and fault tolerance capabilities. We have carried out extensive simulations to evaluate the performance of the proposed scheme. Compared with the well-known KIS encoding scheme, the proposed LRC-based scheme can reduce the label size significantly. An 8-byte LRC label is long enough to support all node pair with five paths in a 300-node network. [Copyright &y& Elsevier]

Abstract: In this article, we introduce a power-hopping technique (PH-MAC) that, by alternating between different transmission power levels, aims to deliberately cause packet capture and thereby reduce the impact of collisions in 802.11 WLANs. We first devise an analytical model of the 802.11 protocol with heterogeneous capture probabilities, and show that, depending on the network load, the capture effect can enhance the throughput performance of all nodes. We base the design of PH-MAC on the findings following from this analysis and demonstrate that important performance improvements can be achieved by exploiting the interactions between the MAC and PHY layers to mitigate collisions. Finally, to understand the feasibility of this technique in practical deployments, we present a prototype implementation of PH-MAC which relies on commodity hardware and open-source drivers. We evaluate the performance of this implementation in an indoor testbed under different network conditions in terms of link qualities, network loads and traffic types. The experimental results obtained show that our scheme can provide significant gains over the default 802.11 mechanism in terms of throughput, fairness and delay. [Copyright &y& Elsevier]

Abstract: Optical packet switch with multicast capability can inspire a broad range of multipoint to multipoint applications in future optical networks. An optical multicast packet switching architecture, equipped with feedback shared small number of limited-range multi-wavelength converters (LMWCs) and output shared some full-range wavelength converters (FRWCs), is proposed for a wavelength-division multiplexed optical multicast network to improve multicast performance in the paper. The FRWCs are used to overcome the performance degradation in terms of packet loss probability due to only use LMWCs. In the architecture, the two converters are shared by all the multicast packets importing to the optical multicast switch node. A maximum bipartite matching with minimum edges weights strategy was designed to employ fewer wavelength converters and avoid useless degradation of optical signal quality for the architecture to improve the node performance. The simulation results show that the proposed architecture and its wavelength converter scheduling algorithm can reduce the multicast packet loss probability with relatively lesser wavelength conversion cost. [Copyright &y& Elsevier]

Abstract: Recently, the need of the high speed packet switch is increased. The basic 2DRR scheduling algorithm provides high throughput, fair access and simple working on a packet switch. However, few input and output node could not be permissioned in some timeslots. It occurs decreasing throughput and some transmission delay. This paper proposes a new packet switch scheduling algorithm. The proposed scheduling algorithm provides higher throughput and low delay. The effectiveness of the proposed algorithm is shown through simulation studies. [Copyright &y& Elsevier]

Abstract: In many-core architectures different distributed applications are executed in parallel. The applications may need hard guarantees for communication with respect to latency and throughput to cope with their constraints. Networks on Chip (NoC) are the most promising approach to handle these requirements in architectures with a large number of cores. Dynamic reservation of communication resources in virtual channel NoCs is used to enable quality of service for concurrent communication. This paper presents a router design supporting best effort and connection-oriented guaranteed service communication. The communication resources are shared dynamically between the two communication schemes. The key contribution is a concept for virtual channel reservation supporting different bandwidth and latency guarantees for simultaneous guaranteed service communication flows. Different to state-of-the-art, the used scheduling approach allows to give hard guarantees regarding throughput and latency. The concept enables to adjust the bandwidth and latency requirements of connections at run-time to cope with dynamically changing application requirements. Due to its distributed reservation process and resource allocation it offers good scalability for many-core architectures. The implementation of a router and the required extension of a network interface to support the proposed concept are presented. The software perspective is discussed. An algorithm is presented that is used to establish guaranteed service connections according to the applications bandwidth requirements. Simulation results are compared to state-of-the-art arbitration schemes and show significant improvements of latency and throughput, e.g. for an MPEG4 application. Synthesis results expose the low area overhead and impact on energy consumption which makes the concepts highly attractive for QoS-constraint many-core architectures. [Copyright &y& Elsevier]

This paper extends RBAC sessions with shareability, reusability and switchability properties. We define the Smatch (Secure MAnagement of swiTCH) model in which authorized users can join, leave, reopen and reuse dynamic sessions. In Smatch, subjects can also share sessions and dynamically switch their role or function with other subjects from the same or different organizations. Subjects can authenticate using their function which will automatically activate the set of roles associated with this function. The Smatch model is based on the situation calculus which extends first order logic with actions. It provides means to specify contextual access control and authentication policies which apply to control functional behavior of dynamic sessions. We formally analyze decidability and complexity of several problems like decision, planning and proof of properties in the Smatch model. We also suggest an implementation of Smatch using Eyeos, an open-source web based Operating System. [ABSTRACT FROM AUTHOR]

Abstract: We proposed and investigated superimposing intensity-modulated labels onto high-speed carrier-suppressed return-to-zero frequency shift keying-modulated payloads in optical label-switching packet networks. The transmission performances of 2.5Gb/s ASK label on 40Gb/s CSRZFSK payload is studied for the first time. [Copyright &y& Elsevier]

Abstract: Self-triggered sampling is an attractive paradigm for closed-loop control over energy-constrained wireless sensor networks (WSNs) because it may give substantial communication savings. The understanding of the performance of self-triggered control systems when the feedback loops are closed over IEEE 802.15.4 WSNs is of major interest, since the communication standard IEEE 802.15.4 is the de-facto reference protocol for energy-efficient WSNs. In this paper, a new approach to control several processes over a shared IEEE 802.15.4 network by self-triggered sampling is proposed. It is shown that the sampling time of the processes, the protocol parameters, and the scheduling of the transmissions must be jointly selected to achieve a good performance of the closed-loop system and an energy-efficient utilization of the network. The challenging part of the proposed analysis is ensuring globally uniformly ultimately boundedness of the controlled processes while providing efficient scheduling of the process state transmissions. Such a scheduling is difficult when asynchronous multiple control loops share the network, because transmissions over IEEE 802.15.4 are allowed only at certain time slots. The proposed approach establishes that the joint design of self-triggered samplers and the network protocol (1) ensures globally uniformly ultimately boundedness of each control loop, (2) reduces the number of sensor transmissions, and (3) increases the sleep time of the transmitting nodes. A new dynamic scheduling problem is proposed for the joint control of each process and network protocol adaptation. An algorithm is derived, which adapts the network parameters according to the self-triggered sampler of every control loop. Numerical examples illustrate the analysis and show the benefits of the approach. It is concluded that self-triggered control strategies over WSNs ensure desired control performance, reduce the network utilization, and reduce energy consumption only if the protocol parameters are appropriately regulated. [Copyright &y& Elsevier]

Abstract: Variable-Bit-Rate (VBR) video transmission over UMTS networks is assuming an ever growing importance, then scheduling VBR data over wireless channels attracts great interest today. This paper proposes an on-line PI control algorithm for easily and suitably scheduling interactive multimedia transmission of VBR video streams. It dynamically adapts the transmitted bit rate to the user''s actions that can suddenly and highly modify the client buffer level. The Real-time Transport Control Protocol (RTCP) packets periodically feed back the buffer level to the server for keeping the free buffer space at 50% of its capacity, so as to prevent both buffer overflow and underflow. Numerical results of different simulated scenarios show the effectiveness of the proposed controller in comparison with two well-established algorithms, enhanced with RTCP information. [Copyright &y& Elsevier]

Abstract: The exponential increase in the data center network traffic has posed new challenges for achieving high throughput, low latency and energy consumption. To address these challenges, this paper presents a novel scheme that combines optical circuit and packet switching technologies together in a single optical cross-connect for data center networks. By utilizing fast tunable linecards and parallel array waveguide grating routers, the optical cross-connect can offer low latency, large scalability and high throughput in datacenter networks. A scheduling technique is designed to simultaneously accommodate circuit switching and packet switching in the optical cross-connect. The physical performance of this optical cross-connect in circuit and packet switching modes is investigated by experiments. In addition, the network performance of the optical cross-connect is evaluated through simulations under a mixed circuit/packet-switched traffic pattern. Results show that the network performance of the optical cross-connect does not degrade significantly with an increase in the number of racks, but it is affected by the circuit-switched traffic proportion. [Copyright &y& Elsevier]

Abstract: In this work, we analyze the power saving and its impact on web traffic performance when customers adopt the continuous connectivity paradigm. To this end, we provide a model for packet transmission and cost. We model each mobile user’s traffic with a realistic web traffic profile, and study the aggregate behavior of the users attached to a base station by means of a processor-shared queueing system. In particular, we evaluate user access delay, download time and expected economy of energy in the cell. Our study shows that dramatic energy saving can be achieved by mobile devices and base stations, e.g., as much as 70%–90% of the energy cost in cells with realistic traffic load and the considered parameter settings. [Copyright &y& Elsevier]

Abstract: In application-layer distributed denial of service (DDoS) attacks, zombie machines attack the victim server through legitimate packets such that packets havelegitimate format and are sent through normal TCP connections. Consequently, neither intrusion detection systems (IDS) nor victim server can detects malicious packets. This paper proposes a novel scheme which is called ConnectionScore to resist against such DDoS attacks. During the attack time, anyconnection is scored based on history and statistical analysis which has been done during the normal condition. The bottleneck resources are retaken from those connections which take lower scores. Our analysis shows that connections established by the adversary give low scores. In fact, ConnectionScore technique can estimate legitimacy of connections with high probability.Toevaluate performanceofthe scheme,weperformexperimentson Emulabenvironmentusingreal traceroute data of ClarkNet WWW server. [Copyright &y& Elsevier]

Abstract: Programmable variable delay lines have been developed, so as to delay packets in variable durations by combining several lengths of Fiber Delay Lines (FDLs) in optical packet switch. In practice, Two-stage variable optical packet switch with this programmable variable delay lines has been proposed. This switch has two buffers. The one is the programmable variable delay lines (Look-ahead Buffer). The other is the fixed FDLs that re-input a packet from the output to the input (Loop-back Buffer). The switch can foresee following packets and avoid contentions effectively by using two buffers. However, existing studies only focus on the Look-ahead Buffer. Intelligent usage of the Loop-back Buffer is actually out of concern. This paper proposes a sophisticated scheduling method in the Two-stage switch. The proposed method controls both the Look-ahead Buffer and the Loop-back Buffer cooperatively and improves the utilization of the switching process. The proposed method uses the Loop-back Buffer adaptively and distributes traffics in time and space domain. The effectiveness of the proposed method is evaluated through extended simulation experiments and basic hardware design. [Copyright &y& Elsevier]

Abstract: Optical burst switching is a promising all-optical switching technology for the next generation optical networks and signaling is one of the key components of it. According to propagation direction of control packets, the existing signaling schemes for optical burst switched networks can be roughly divided into three categories: one-way, two-way, and hybrid signaling. Since one-way signaling launches bursts without the acknowledgment of successful reservation of resources, it has small end-to-end delay but high data loss rate; two-way signaling uses a control packet to gather the state of links and needs the successful acknowledgment before sending out a burst, so it has large end-to-end delay but low data loss rate. A hybrid signaling gets a tradeoff of performance between one-way and two-way signaling. In this paper, we propose another hybrid signaling named inverse two-way signaling. By introducing the process of link state collection into one-way signaling, the inverse two-way signaling can decrease the data loss rate without increasing the end-to-end delay compared to one-way signaling. In other words, the inverse two-way signaling is an improved version of one-way signaling. [Copyright &y& Elsevier]

Abstract: There has been much interest to emulate the behavior of Output Queued switches. The early result of such attempts was reported by Prabhakar and McKeown using the CIOQ switches with speedup factor of 4. Subsequently, Stoica and Zhang and independently Chuang et al. showed that a speedup of 2 in conjunction with their scheduling schemes would be sufficient for CIOQ switches to emulate Output Queued switches. Additionally, Chuang et al. showed that in “Average Sense” a speedup of 2−1/N is necessary and sufficient for CIOQ to emulate Output Queued switch behavior. Our paper reports that in the “Strict Sense” a speedup of 2 is both necessary and sufficient. We show this requirement using examples for 2x2 and 3x3 switches. Then, with a constructed traffic pattern, it is proved that in the “Strict Sense” a speedup of 2 is necessary to emulate the behavior of an Output Queued switch for any switch size N. Combining this result with the previous scheduling schemes, we conclude that in the “Strict Sense”, a speedup of 2 is the necessary and sufficient condition to emulate the behavior of an Output Queued switch, using a CIOQ switch. Additionally, easing the assumptions and allowing the packet segmentation, it is shown that the speedup requirement to emulate the behavior of an Output Queued switch can be reduced to values even smaller than 2−1/N. For this case a lower bound of 3/2 and an upper bound of 2 is proved. [Copyright &y& Elsevier]

Abstract: The basic standard protocol for supporting network mobility (NEMO) (i.e., NEMO-BSP specified by IETF) introduces several performance problems, such as multiple tunneling overhead and packet delivery latency, because it exploits mobile IPv6 (MIPv6), which was proposed for host mobility. To improve the basic NEMO solution, two network-based NEMO approaches, rNEMO and N-PMIPv6, have been proposed. The rNEMO is able to reduce significant packet tunneling overhead. The N-PMIPv6, on the other hand, reduces location update cost, but it leads to packet tunneling overhead. Thus, they commonly waste network resources in both wired and especially wireless network. No efficient and practical solutions for minimizing both the location update overhead and packet tunneling overhead have been presented until now. This situation motivated us to propose a resource-efficient network mobility scheme (RENEMO), reducing resource utilization required for network mobility support. We show that the proposed RENEMO outperforms both rNEMO and N-PMIPv6 in terms of network resource. [Copyright &y& Elsevier]

Abstract: Packet-switching WDM ring networks with a hotspot transporting unicast, multicast, and broadcast traffic are important components of high-speed metropolitan area networks. For an arbitrary multicast fanout traffic model with uniform, hotspot destination, and hotspot source packet traffic, we analyze the maximum achievable long-run average packet throughput, which we refer to as multicast capacity, of bi-directional shortest path routed WDM rings. We identify three segments that can experience the maximum utilization, and thus, limit the multicast capacity. We characterize the segment utilization probabilities through bounds and approximations, which we verify through simulations. We discover that shortest path routing can lead to utilization probabilities above one half for moderate to large portions of hotspot source multi- and broadcast traffic, and consequently multicast capacities of less than two simultaneous packet transmissions. We outline a one-copy routing strategy that guarantees a multicast capacity of at least two simultaneous packet transmissions for arbitrary hotspot source traffic. [Copyright &y& Elsevier]

Abstract: Due to the rapid development of network applications, today the Internet plays an important role in our everyday life. Users hope that the network is always speedy enough to help them access the Internet without any delay. But the real situation is far from the ideal case. In the future, network researchers will continuously improve the network speed, and try to develop networks that are robust, without any crashes or packet loss. In this paper, we propose an aggressive path switching scheme for SCTP. Before data transmission, the scheme selects the fastest path as the primary path to transmit packets. When the path fails or transmission quality is poor, this scheme evaluates alternate paths, and selects the one with the best quality as the new primary path to substitute for the original one. After that, packets are delivered through the new path. Several factors are considered in the evaluation, including bandwidth, encryption/decryption, size of the congestion window, retransmission policy, routing policy, etc. [Copyright &y& Elsevier]

Abstract: In the problem of buffer management with bounded delay, packets with weights and deadlines arrive at a network switch over time, and the goal is to send those packets on the outgoing link while maximizing the total weight of the packets that are sent before their deadlines. We present a study of randomized algorithms that are competitive against an adaptive adversary. Previous studies considered only the oblivious adversary model that does not capture dependency of network traffic on the packet scheduling algorithm. We give a new analysis of a previously known algorithm, which shows that it remains -competitive even against an adaptive adversary. We complement this with a 4/3 lower bound on the competitive ratio on 2-bounded instances, in which each packet has a lifespan of one or two steps. We also study more restricted 2-uniform instances, in which every packet has a lifespan of exactly two steps. For such instances we give a 1.2 lower bound on the competitive ratio of arbitrary algorithms and 4/3 lower bound on the competitive ratio of memoryless scale-invariant algorithms. Finally, we devise a 4/3-competitive memoryless scale-invariant algorithm for 2-bounded instances, matching two of these lower bounds. [Copyright &y& Elsevier]

Abstract: Localization protocol is important for estimating node positions in a wireless multi-hop network. Routing protocol is also important for controlling paths. In previous research, localization and routing protocols have been discussed and evaluated separately. In this paper, we propose an integrated protocol for optimized link state routing (OLSR) and OLSR based localization (ROULA). Our protocol enables simultaneous localization and routing. ROULA’s localization is performed using OLSR overhead such as hello packets and routing tables. The routing overheads and the processing procedures can be efficiently integrated. We demonstrate that the integrated protocol for ROULA and OLSR enables simultaneous localization and routing. [Copyright &y& Elsevier]

Abstract: In the Optical Burst Switching (OBS) Network, the burst assembly technique is one of the challenging issues in the implementation of the system. It has the influence on the burst characteristic, which gives an impact on the network performance. Burst assembly is the process of assembling incoming data from the higher layer into bursts at the ingress edge node of the OBS network. The burst assembly mechanism must then place these packets into bursts based on some assembly policy. In this paper, the OBS system performance has been observed in simulated 12-node network based on Just-Enough-Time (JET) reservation protocol with various burst assembly techniques under the standard drop policy (DP) and the segmentation policy for contention resolution. The simulation results show that the performance of the proposed Adaptive-Threshold with Fixed Maximum Time Limitation (ATH-FMTL) burst assembly scheme is better than conventional burst assembly schemes in terms of loss probability and average assembly delay. Also, the proposed scheme avoids a sudden increase in the burst size and makes the burst sent out smoother as compared to conventional schemes. [Copyright &y& Elsevier]

Abstract: TCP-over-OBS is a promising transport paradigm to support next-generation Internet. It is well known that load-balanced routing generally improves loss performance over OBS. We identify that implementing TCP over load-balanced OBS could lead to persistent out-of-order delivery of TCP segments, resulting in unnecessary timeouts and fast retransmissions. In this paper we evaluate the performance of Reordering-Robust TCP (RR-TCP) over OBS networks. We develop an analytical end-to-end transfer delay model for TCP SACK and RR-TCP over load-balanced OBS networks. We observe that standard TCP experiences significant throughput degradation due to persistent packet reordering. Through simulations and modeling we show that RR-TCP achieves significant improvement compared to TCP SACK. In our simulations we add High-Speed TCP functionality to RR-TCP (HS-RR-TCP). The simulations show up to a 300% performance improvement for HS-RR-TCP compared to HS-TCP-SACK under ideal conditions and a 20% improvement on NSFnet with background traffic. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents PI-OPS (Parallel-Iterative Optical Packet Scheduler) a parallel-iterative scheduler for asynchronous Optical Packet Switching nodes with optical buffering. Optical packets are assembled by aggregating IP packets, and attaching an optical packet header. Conventional schemes process optical packet headers one by one, in a sequential form. Then, the worst case algorithm response time is tightly coupled to switch size. In contrast, in PI-OPS all the optical packets received during a given time window are jointly processed to optimize the delay and output wavelength allocation, applying void filling techniques. The scheduler has a deterministic response time, independent of the traffic arrival’s pattern. In addition, PI-OPS has been specifically designed to allow a parallel electronic implementation similar to the ones found in VOQ schedulers. In this respect, we evaluate the traffic loss performance of the scheduler in different settings, to dimension a set of hardware related parameters. Finally, we conduct an emulation of an FPGA implementation of a large-scale version of the scheduler. Results support the feasibility of its implementation. [ABSTRACT FROM AUTHOR]

Abstract: The most promising solutions to increase bandwidth efficiency in IP over DWDM networks are represented by Optical Packet and Burst Switching. Due to the statistical multiplexing approach adopted, these paradigms must deal with packet/burst contentions at the node output channels and require the use of scheduling algorithms to optimize resource assignment and bandwidth utilization. However, very strict time constraints on the scheduling operations are imposed by the extremely high bit rates used, making the actual feasibility of the scheduler control logic a major implementation issue common to both technologies. This paper provides a specific formulation of the scheduling problem that can be used as the basis for the practical design of a fast and versatile scheduler, capable of implementing many algorithms found in literature. A possible implementation of the scheduler sub-functions, mainly based on the use of combinatorial operations, is also discussed and supported by the simulation of the hardware implementation time response, with results that demonstrate the feasibility of the proposed solution. [ABSTRACT FROM AUTHOR]

Abstract: We demonstrate packet detection at an optical switch input using an optoelectronic control system which then processes the headers of the packets, and controls the switching according to the header content for both fixed and variable length packets arriving synchronously or asynchronously at the optical switch. Furthermore, contention resolution is demonstrated in an optical Crosspoint switch by detecting packets at the input ports and controlling the switch operation accordingly. By incorporating this control system into the Crosspoint switch it is possible to route contending packets to a recirculating fibre delay line and to control the switch output in a flexible manner for any type of traffic depending on the applied switching algorithm. The feasibility of a recirculating buffer implementation is supported by the very low crosstalk characteristics of the Crosspoint switch. The experiments are done with 155 Mb/s headers and 10 Gb/s payloads transmitted on a single wavelength with a guard time of 12.8 ns between the header and the payload. Error-free photonic switching of fixed and variable length packets and contention resolution of fixed length packets are shown, with the main signal degradation being from the switch cell attenuation and amplified spontaneous emission (ASE) which can be alleviated by eliminating fibre-to-fibre transmission loss in the Crosspoint switch. [ABSTRACT FROM AUTHOR]