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Packet-switched xHaul networks are a scalable solution enabling convergent transport of diverse types of radio data flows, such as fronthaul / midhaul / backhaul (FH / MH / BH) flows, between remote sites and a central site (hub) in 5G radio access networks (RANs). Such networks can be realized using the cost-efficient Ethernet technology, which enhanced with time-sensitive networking (TSN) features allows for prioritized transmission of latency-sensitive fronthaul flows. Provisioning of multiple types of 5G services of different service requirements in a shared network, commonly referred to as network slicing, requires adequate handling of transported data flows in order to satisfy particular service / slice requirements. In this work, we investigate two traffic prioritization policies, namely, flowaware (FA) and latency-aware (LA), in a packet-switched xHaul network supporting slices of different latency requirements. We evaluate the effectiveness of the policies in a networkplanning case study, where virtualized radio processing resources allocated at the processing pool (PP) facilities, for two slices related to enhanced mobile broadband (eMBB) and ultra-reliable low latency communications (URLLC) services, are subject to optimization. Using numerical experiments, we analyze PP cost savings from applying the LA policy (vs. FA) in various network scenarios. The savings in active PPs reach up to 40% - 60% in ring scenarios and 30% in a mesh network, whereas the gains in overall PP cost are up to 20% for the cost values assumed in the analysis. [ABSTRACT FROM AUTHOR]

Abstract This paper proposes a novel Krasovskii–LaSalle theorem for discrete-time switched linear time-invariant systems. The result is utilized to guarantee exponential convergence of both leaderless and leader-following consensus of discrete-time multi-agent systems under jointly connected switching network topology. Different from the continuous-time multi-agent systems under switching networks, where the magnitude of the dwell time of switching signals is irrelevant, in the discrete-time case, this value is critical for consensus reaching. A special index, called the constrained controllability index, is defined. This index can be easily calculated and provide a tighter lower bound of the dwell time when compared to those given in the literature. With our novel method, the controllability condition on the system matrix is relaxed to the stabilizability condition, and the proposed results not only expand the existing discussions to balanced switching networks but also cover some unbalanced networks. Finally, numerical examples and simulations are provided to verify the theoretical results. [ABSTRACT FROM AUTHOR]

This paper investigates the sampled-data synchronization of switched neural networks with time-varying discrete and distributed delays. Considering that the system switching may happen during a sampling interval, the asynchronous phenomenon is taken into account for the sampled-data control process. By utilizing multiple Lyapunov functions and average dwell time property, sufficient conditions are derived to guarantee the exponential stability of the error between the master and slave neural networks. Based on this, sampled-data controller is further designed so that the master and the slave systems are synchronized with a prescribed performance index. Finally, a numerical example is provided to illustrate the validness and effectiveness of the proposed results. [ABSTRACT FROM AUTHOR]

In this paper, we apply formal verification and falsification of temporal logic specifications to analyze chemical plant automation systems. We present new results, obtained by applying a recently-developed approach to handle combined invariance and reachability requirements. In addition, we develop a set of tests that can be generated automatically for a given control system, some of which have the same form as those in the existing literature, and some of which combine invariance and reachability, to which we apply the new approach mentioned previously. In both cases, we work with abstractions of the automation systems in order to apply symbolic model checking to industrial-scale problems. We demonstrate the results using a series of small illustrative examples, and also report results from an industrial case study. The methods that we apply are implemented in a pair of open-source software tools, which we describe briefly. [ABSTRACT FROM AUTHOR]

Domain of attraction plays an important role in control systems analysis, which is usually estimated by sublevel sets of Lyapunov functions. In this paper, based on the concept of common Lyapunov-like functions, we propose an iteration method for estimating domains of attraction for a class of switched systems, where the state space is divided into several regions, each region is described by polynomial inequalities, and any region has no intersection among with each other. Starting with an initial inner estimate of domain of attraction, we first present a theoretical framework for obtaining a larger inner estimate by iteratively computing common Lyapunov-like functions. Then, for obtaining a required initial inner estimate of domain of attraction,we propose a higher-order truncation and linear semidefinite programming--based method for computing a common Lyapunov function. Successively, the theoretical framework is under-approximatively realized by using S-procedure and sum-of-squares programming, associated with a coordinatewise iteration idea. Finally, we implement our method and test it on some examples with comparisons. These computation and comparison results show the advantages of our method. [ABSTRACT FROM AUTHOR]

By applying first-principles method based on density functional theory combined with nonequilibrium Green's function, we investigate the effect of torsion angle on the electronic transport properties in dipyrimidinyl-diphenyl co-oligomer molecular device with tailoring graphene nanoribbon electrodes. The results show that the torsion angle plays an important role on the electronic transport properties of the molecular device. When the torsion angle rotates from 0 to 90, the molecular devices exhibit very different current-voltage characteristics which can realize the on and off states of the molecular switch. [ABSTRACT FROM AUTHOR]

We consider a generic deterministic time-invariant fluid model of a single server switched network, which consists of finitely many infinite size buffers (queues) and receives constant rate inflows of jobs from the outside. Any flow undergoes a multi-phase service, entering a specific buffer after every phase, and ultimately leaves the network; the route of the flow over the buffers is pre-specified, and flows may merge inside the network. They share a common source of service, which can serve at most one buffer at a time and has to switch among buffers from time to time; any switch consumes a nonzero switchover period. With respect to the long-run maximal scaled wip (work in progress) performance metric, near-optimality of periodic scheduling and service protocols is established: the deepest optimum (that is over all feasible processes in the network, irrespective of the initial state) is furnished by such a protocol up to as small error as desired. Moreover, this can be achieved with a special periodic protocol introduced in the paper. It is also shown that the exhaustive policy is optimal for any buffer whose service at the maximal rate does not cause growth of the scaled wip. [ABSTRACT FROM AUTHOR]

In this paper, a GaAs absorptive single-pole double-throw (SPDT) RF switch and its application to a 2.4-GHz switched beamformer module are presented. The proposed absorptive SPDT RF switch features low-power consumption and low insertion loss with good output matching both in the on and off states. Specifically, the measured insertion loss in the on state is less than 1 dB, and the measured input and output return losses are both better than 11.2 dB from 1.9 to 2.6 GHz. The measured output return loss in the off state is better than 15 dB, and the measured isolation is better than 24.7 dB in the same frequency range. Two proposed absorptive SPDT switches are then employed to form an absorptive single-pole four-throw RF switch, and it is integrated with a miniaturized $4 \times 4$ Butler matrix using the integrated passive device (IPD) technology to achieve a compact 2.4-GHz switched beamformer module with a very low profile. Specifically, the module size is 4.9 mm $\times5$ mm with a thickness of only 0.4 mm. The IPD beamformer module is then used to realize a low-profile 2-D scanning antenna array, and 16 different beams in azimuth and elevation dimensions are successfully generated. [ABSTRACT FROM PUBLISHER]

This paper analyzes write errors in spin-torque switching due to thermal fluctuations in a system with perpendicular magnetic anisotropy. Prior analytical and numerical methods are summarized; a physics-based general 2-D Fokker–Planck equation (FPE) is solved numerically. Due to its computational efficiency and broad applicability to all switching regimes and system symmetries, the 2-D FPE has been used to study the relation between write error slope and material parameters as well as some emerging switching schemes. [ABSTRACT FROM PUBLISHER]

The telecommunications industry has used the time deviation (TDEV) very effectively for specifying network equipment clock performance as well as the performance of timing signals generated by Central Office equipment such as primary reference clocks and building integrated timing supplies (BITS) and synchronization supply units (SSUs). We discuss here the development of TDEV, and the variations of TDEV motivated by the advent of packet-switching and the steady transformation of the telecom network from circuit-switched-based to packet-switched-based. We illustrate these with simulation of the performance of the precise time protocol (PTP) across a packet-switched network. We then apply published methods to automatically determine noise types, and use these to predict time dispersion from a master clock for a slave clock using these PTP packets to stay synchronized. The result shows how TDEV and the other deviations provide an extensive array of tools for telecom networks, as well as for general time and frequency applications. [ABSTRACT FROM AUTHOR]

In this work, according to the concept of 'area' on the v-i plane, a new approach called swept area theory, under both nonlinear continuous and discontinuous conditions, is developed. Novel conservative functions, such as area velocity and closed area over time (CAT), involved in this theory, are proposed. An analysis is carried out, by means of these functions, over nonlinear R, L, and C elements and over the ideal switch. In addition, jump discontinuities are discussed in detail. The CAT is related to the harmonic reactive powers and under sinusoidal steady state becomes proportional to the classical reactive power. A balance rule concerning harmonic reactive powers over nonlinear resistor under continuous conditions is obtained and discussed as a novel interesting result. This aspect impacts on a possible expanded definition of reactive power under distorted conditions. Thanks to the switching power, a novel quantitative relation between hard-switching commutations and CAT is obtained, with both theoretical and applicative relevance. More explanation is presented through a demonstration that shows how an ideal switch and power converters can become sources of reactive power. Issues of principle regarding the ideal switch model with respect to the real one are another important result of this work. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, we study a two-phase underlay cognitive relay network, where there exists an eavesdropper who can overhear the message. The secure data transmission from the secondary source to secondary destination is assisted by two decode-and-forward (DF) relays. Although the traditional opportunistic relaying technique can choose one relay to provide the best secure performance, it needs to continuously have the channel state information (CSI) of both relays, and may result in a high relay switching rate. To overcome these limitations, a secure switch-and-stay combining (SSSC) protocol is proposed where only one out of the two relays is activated to assist the secure data transmission, and the secure relay switching occurs when the relay cannot support the secure communication any longer. This security switching is assisted by either instantaneous or statistical eavesdropping CSI. For these two cases, we study the system secure performance of SSSC protocol, by deriving the analytical secrecy outage probability as well as an asymptotic expression for the high main-to-eavesdropper ratio (MER) region. We show that SSSC can substantially reduce the system complexity while achieving or approaching the full diversity order of opportunistic relaying in the presence of the instantaneous or statistical eavesdropping CSI. [ABSTRACT FROM AUTHOR]

Invariant measures of iterated function systems and refinable functions are mathematical tools of vast usage, that, although usually considered in different contexts, are deeply linked. We outline these links, in particular with respect to existence and regularity of these objects. [ABSTRACT FROM AUTHOR]

Systems with high computational capabilities are usually made of a large number of processing elements in order to solve complex problems efficiently. To achieve this purpose, the processing elements must be able to communicate with each other, which can be provided by interconnection networks. Meanwhile, multistage interconnection networks (MINs) are often recommended for use in such systems due to the efficiency and cost-effectiveness. However, there is a fundamental problem in the general structure of these networks called blocking. An important class of MINs is rearrangeable non-blocking MINs that can be used as a cost-effective solution to cope with the blocking problem. Benes network is one of the most popular rearrangeable non-blocking MINs, which has been considered by many researchers over the years. And yet its reliability improvement is an important factor that must be considered in the review of most systems, especially large-scale ones. Based on previous works, there are three main approaches to improve the reliability of MINs: (1) Adding a number of stages to MIN. (2) Using multiple MINs in parallel. (3) Using replicated MINs. In this paper, in order to find the best solution to improve the reliability of the Benes network, all three of these methods are investigated. Reliability analyses show that the use of multiple parallel Benes networks can obtain more advantages than other methods for Benes network. The approach improves the Benes network to be used in large-scale systems in various aspects of reliability namely time-independent terminal reliability, time-independent broadcast reliability, time-dependent terminal reliability, and time-dependent broadcast reliability. [ABSTRACT FROM AUTHOR]

This paper studies the problem of H ∞ output tracking control for a class of discrete-time switched systems. Neither the measurability of the system state nor the solvability of the output tracking control problem for each individual subsystem is required. We design controllers for subsystems and a switching law to solve the H ∞ output tracking problem for the switched system. The designed controllers use only the measured output feedback, and the switching law is based on the measured output tracking error. In addition, the quadratic function corresponding to each subsystem is not required to be positive definite. A numerical example is provided to demonstrate the feasibility and validity of the proposed design method. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This work is devoted to the study of the strong minimality of a class of iterated function systems defined on the two dimensional torus T2. This means that almost every orbital branch of each point is dense in the ambient space. Moreover, we prove that this property is robust under small perturbations of the generators. [ABSTRACT FROM AUTHOR]

In this paper, we propose a reduced complexity stochastic joint source-channel coding system developed for efficient and robust coding of wideband speech ISF (Immittance Spectral Frequency) parameters. Initially, the aim of this encoding system was to achieve a transparent quantization of ISF parameters for ideal transmissions over a noiseless channels. It was designed based on the switched split vector quantization (SSVQ) technique and called “ISF-SSVQ coder”. After that, our interest was drawn to the improvement of the ISF-SSVQ robustness for transmissions over a noisy channel. To protect implicitly our ISF coders, we developed a stochastic joint source-channel coding system based on a reduced complexity version of the channel optimized SSVQ technique. Simulation results will show that our new encoding system, called ISF-SCOSSVQ coder, can provide a good implicit protection to ISF parameters. The ISF-SCOSSVQ coder was further used to encode the ISF parameters of the Adaptive Multi-rate Wideband (AMR-WB, ITU-T G.722.2) speech coder operating over a noisy channel. We will show that the proposed ISF-SCOSSVQ coder contribute significantly in the improvement of the AMR-WB performance by ensuring a good coding robustness of its ISF parameters. [ABSTRACT FROM AUTHOR]

Traditionally in redundancy allocation problem (RAP), it is assumed that the redundant components are used based on a predefined active or standby strategies. Recently, some studies consider the situation that both active and standby strategies can be used in a specific system. However, these researches assume that the redundancy strategy for each subsystem can be either active or standby and determine the best strategy for these subsystems by using a proper mathematical model. As an extension to this assumption, a novel strategy, that is a combination of traditional active and standby strategies, is introduced. The new strategy is called mixed strategy which uses both active and cold-standby strategies in one subsystem simultaneously. Therefore, the problem is to determine the component type, redundancy level, number of active and cold-standby units for each subsystem in order to maximize the system reliability. To have a more practical model, the problem is formulated with imperfect switching of cold-standby redundant components and k-Erlang time-to-failure (TTF) distribution. As the optimization of RAP belongs to NP-hard class of problems, a genetic algorithm (GA) is developed. The new strategy and proposed GA are implemented on a well-known test problem in the literature which leads to interesting results. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel inter-domain connection provisioning mechanism for multi-domain translucent Wavelength Switched Optical Networks. The mechanism can operate in hierarchical and non-hierarchical path computation element-based architectures. It is based on a novel approach to derive the domain abstract topologies jointly with an inter-domain routing algorithm. The overall objective is to perform end-to-end route computations for incoming connections. We do so by taking into account the current load of the physical links and some energy parameters of the optical network devices with the purpose of distributing the load (as much as possible) along the physical links and keeping the energy consumption low. The performance of the whole mechanism is highlighted through extensive and illustrative simulation results that benchmark it against shortest path-based techniques. [ABSTRACT FROM AUTHOR]

A novel null scanning patch antenna operating at 2.4 GHz is presented. Unlike the existing reconfigurable techniques, the even and odd modes of a shorted patch are adopted to first achieve a broadside pattern and pattern null on broadside. Continuous null scanning is achieved by combining these two modes with different exciting powers. The mechanism of null scanning is discussed from both theoretical analysis and simulated/measured results. A rat-race switching network is used to excite the two modes and simultaneously obtain high port isolation. A prototype is fabricated and tested. The measured results verified the null scanning capability of the proposed design. [ABSTRACT FROM PUBLISHER]

The set of arrangements known as the Public Switched Telephone Network ("PSTN") is the foundation for the modern global communications system and the myriad benefits it delivers. Today, the era of the PSTN is swiftly coming to a close. The transition to a broadband network of networks is the most important communications policy event in at least half a century, yet its significance is not fully appreciated. The time has come to address the situation squarely. What we call the PSTN is actually six different concepts: a technical architecture, a regulatory arrangement, a business and market structure, universal connectivity, strategic national infrastructure, and a social contract. The earlier elements on the list are rooted in the particular historical, legal, and technical circumstances that gave birth to the PSTN. They are anachronistic in the current environment and should be restructured or, when appropriate, eliminated. The later elements are public policy obligations that should be satisfied regardless of the historical circumstances. Separating the dimensions of the transition in this way highlights the central importance of interconnection and coordination mechanisms to meet enduring public interest objectives. By adopting a forward-looking plan for the PSTN transition, the FCC can ensure that the shift to a digital broadband world reinforces, rather than undermines, the achievements of the past century of communications policy. [ABSTRACT FROM AUTHOR]

The article discusses the research and development (R&D) trends in optical switch technologies required for colorless, directionless and contentionless reconfigurable optical add/drop multiplexers (CDC-ROADM). It provides an overview of the colorless, directionless and contentionless functions. The authors suggest using wavelength selective switch with 20 or more output ports. They also created a CDC-ROADM node configuration modeled on silica-based planar lightwave circuit technology.

Switched-mode converters are often the key to operating various electronic systems in everyday life. This means that the reliable operation of the converters is of prime importance and that the functioning must be verified during both the design phase and production. Recent studies have shown that the converters can be fully characterized by a set of frequency responses that can be efficiently used to validate the operation of the converters and analyze the related systems. Several methods have been proposed for quickly and accurately measuring the frequency responses, but surprisingly, the use of multiple-input multiple-output (MIMO) identification techniques has not been considered. Applying MIMO identification techniques, the operating conditions of a converter can be kept constant during the frequency-response measurements, and the overall measurement time can be further shortened. This paper reviews the techniques and proposes an implementation setup. The presented techniques provide efficient means to characterize the switched-mode converters during one measurement cycle. The methods can be used for example in field-programmable gate-array-based controller implementation and in fast online analysis. Experimental measurements are shown from a high-frequency switched-mode converter. [ABSTRACT FROM PUBLISHER]

This article provides motivation for the elastic optical network (EON) approach, an efficient and cost-effective solution for provisioning of cloud computing traffic. As opposed to wavelength switched optical networks (WSONs), the capabilities of which are limited by the use of rigid frequency grids, EON architectures allow for both scalable bandwidth provisioning and flexible resource allocation. The deployment cost, energy consumption, and bandwidth usage for both EON and classical WSON transport networks are compared in pan-European and U.S. backbone networks for 2012?2020 using Cisco traffic predictions. Results show that the EON concept significantly outperforms WSON in all examined criteria, and the gap between the two architectures increases in subsequent years. Moreover, potential advantages of anycast routing in transport networks with data center traffic are demonstrated. [ABSTRACT FROM PUBLISHER]

In this paper, we examine the problem of packet scheduling in a single-hop multichannel system, with the goal of minimizing the average message waiting time. Such an objective function represents the delay incurred by the users before receiving the desired data. We show that the problem of finding a schedule with minimum message waiting time is NP-complete, by means of polynomial time reduction of the time table design problem to our problem. We present also several heuristics that result in outcomes very close to the optimal ones. We compare these heuristics by means of extensive simulations. [ABSTRACT FROM AUTHOR]

Purpose – This paper aims to investigate the fast attitude coordinated control problem for rigid satellite swarms with communication delays. Design/methodology/approach – Based on behavior-based control approach, the attitude control system is designed to guarantee that the attitude of the satellite swarm converge to a dynamic reference state in finite time. A fast sliding mode is developed to improve the convergence rate and robustness of the control system. All the effects of communication delays, parameter uncertainties and external disturbances are taken into account simultaneously, and the communication topology of the satellite swarm can be arbitrary types. Numerical simulations are provided to demonstrate the analytic results. Findings – Despite the existence of communication delays, parameter uncertainties and external disturbances, the stability of the closed-loop system can be successfully guaranteed and the proposed control strategies are effective to overcome these unexpected phenomena subject to arbitrary communication topology. Originality/value – This paper introduces a fast terminal sliding mode control method which can guarantee the fast convergence of the attitude state of the satellite swarm in the presence of communication delays, switched communication topology, parameter uncertainties and external disturbances. [ABSTRACT FROM AUTHOR]

The application of queueing network models to the performance analysis of message-switched (or packet-switched) communication networks is surveyed. The main topics covered are the analysis of end-to-end delay and the analysis of buffer management schemes. A brief discussion on flow control is also included. A queueing network model is developed for a simple user-resource network. The mean response time of a host computer in this network is illustrated by a numerical example. [ABSTRACT FROM AUTHOR]

We have designed and measured single flux quantum (SFQ) circuits for data switching at 2.5 Gbps. A fully functional 2/spl times/2 switching node is presented. The node can be used to form a larger switching fabric (4/spl times/4, 8/spl times/8, etc.). The node accepts data streams at either or both inputs, routing the data based on address bits present in the data stream. This approach allows the data to be self-routing and the switch to be self-synchronous. In addition, the switch can route data correctly on an active input line if the other is idle. [ABSTRACT FROM PUBLISHER]

Single-mode operation of fibre-pigtailed distributed feedback semiconductor lasers in the 2.05 μm range has been demonstrated. The lasers are packaged inside standard butterfly modules with output powers in excess of 10 mW at the end of polarisation maintaining optical fibre. The fibre-pigtailed lasers show excellent sidemode suppression ratios ( > 50 dB) and have a mode-hop free tunability larger than 1 nm. The output of the optical fibre has linear polarisation with better than 20 dB extinction over the operating current and temperatures. [ABSTRACT FROM AUTHOR]

Concatenating multicamera videos with differing centers of projection into a single panoramic video is a critical technology of many important applications. We propose a real-time video fusion approach to create wide field-of-view video. To provide a fast and accurate video registration method, we propose multistage hashing to find matched feature-point pairs from coarse to fine. In the first stage of multistage hashing, a short compact binary code is learned from all feature points, and then we calculate the Hamming distance between each two points to find the candidate-matched points. In the second stage, a long binary code is obtained by remapping the candidate points for fine matching. To tackle the distortion and scene depth variation of multiview frames in videos, we build hybrid transformation with depth adjustment. The depth compensation between two adjacent frames extends into multiple frames in an iterative model for successive video frames. We conduct several experiments with different dynamic scenes and camera numbers to verify the performance of the proposed real-time video fusion approach. [ABSTRACT FROM AUTHOR]

Circuit Switched Fallback (CSFB) is the most commonly used method to support voice services over Long Term Evolution (LTE) networks today, as the deployment of IP Multimedia Subsystem (IMS) is still in its infancy. In this article, we discuss the performance of CSFB voice traffic redirection from LTE to UMTS using data from live commercial networks. The key factors impacting CSFB call setup delay are highlighted. Data from multiple cell geometries including stationary and mobility conditions are presented for Mobile Originated (MO) calls towards landlines, Mobile Terminated (MT) calls from landlines and Mobile-to-Mobile (M2M) CSFB calls. Analysis results in well optimized deployments show that on an average, MO/MT call-setup time for CSFB from LTE to UMTS is around 1 sec greater than legacy UMTS. However, the results can vary depending on the network configuration and the conditions of the measurement. To illustrate the optimization of CSFB performance in real networks, we also highlight the principal call set up optimization and implementation factors impacting CSFB call setup delay and success rates. This article demonstrates that in well optimized networks, CSFB to UMTS call setup success rates can be very close to those achieved in the legacy UMTS systems. [ABSTRACT FROM PUBLISHER]