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This paper aims to give general conditions on switchings thresholds to ensure the switchings existence for a particular class of hybrid dynamical systems. We develop here the study considering systems of this class in dimension one and, above all, in dimension two. We finally conclude that those conditions could be applied to any dimension systems of this hybrid systems class and we illustrate all results with a thermal application. [ABSTRACT FROM AUTHOR]

Crossbars are main components of communication switches used to construct interconnection networks. Scheduling algorithm controls contention in switch architecture. Several scheduling algorithms were proposed for input-queued crossbar switch architectures. This paper suggests a Dynamic Scheduling Algorithm (DSA). This algorithm changes the priority rotation dynamically based on two parameters: queue occupancy and quality of service of input and output. DSA efficiently utilizes the buffers and at the same time gives good service to the selected inputs and outputs. The simulation results show that DSA saves loss of the cells due to buffer overflow and thus increases the throughput by 2% to 4% compared to its counter part. DSA reduces the latency for prescribed Quality of Service class input output and increases the average latency. [ABSTRACT FROM AUTHOR]

The article provides information on packet-switched networks. Packet-switched networks are becoming the dominant method of communication, replacing earlier schemes based on the telephone-type circuit-switched networks. Telephone networks are based on the idea of circuit switching. The dominant application supported by the circuit-switching architecture is voice and it is assumed that the bandwidth required between two users is determined by the bandwidth needed for transmitting good-quality analog voice or 8 kHz.

The article provides information related to optical switches. As an article in the journal "Nature," indicated, the theoretical maximum bandwidth of a typical optical fiber in access networks is estimated to be about 150Tbps. Dense wavelength-division multiplexing systems can deliver information in a number of wavelengths in one optical fiber. Without optical logic technology, the switching nodes need to undergo signal conversions from photons to electrons in order to switch packets to their respective outgoing ports.

This article presents information on videotelephony and multimedia for circuit for circuit-switched and wireless networks. ITU-T Recommendation H.324 is the international standard for videotelephony and real-time multimedia communication systems on low-bit-rate circuit-switched networks. The basic H.324 protocol can be used over almost any circuit-switched network, including modems on the public switched telephone network. H.324 is a "toolkit" standard that gives implementers flexibility to decide which media types and features are needed in a given product, but ensures interoperability by specifying a common baseline mode of operation for all systems. Above all, H.324 is designed to provide the best performance possible on low-bit-rate networks.

This article presents information on the General Packet Radio Service (GPRS). GPRS is a data bearer service for GSM and IS136 cellular networks. Its packet-oriented radio transmission technology enables efficient and simplified wireless access to Internet protocol-based networks and services. In conventional GSM networks without GPRS, access to external data networks from GSM mobile devices has already been standardized in GSM phase 2; however,on the air interface, such access occupied a complete circuit-switched traffic channel for the entire call period. In case of bursty traffic, it is obvious that packet-switched bearer services result in a much better utilization of the traffic channels.

Bridges operate by examining MAC layer addresses, using the destination and source addresses within a frame as a decision criterion to make their forwarding decisions. Operating at the MAC layer, bridges are not addressed, and must therefore examine all frames that flow on a network. A transparent bridge examines MAC frames to learn the addresses of stations on the network, storing information in internal memory in the form of an address table. One of the key advantages of a transparent bridge is that it operates independently of the contents of the information field and is protocol-independent.

The article discusses the performance objectives of the digital network which support the public switched telephone network. The digital network is based on 8-bit pulse-code modulation (PCM). A PCM network can be synchronized either in bit, timeslot and frame. It is required that each switch in a digital network generate outgoing bit streams. Thus, to achieve such process, network synchronization is important.

The article provides information on the functions of switching in a telecommunications network. A switch adds to the total jitter and wander accumulation across the network. Switching is responsible to interconnect end-user stations such as telephones of a large number of customers. A switch or exchange is divided into three functional areas namely control, connection and operation and maintenance functions.

The article presents a definition for the term "signaling," which refers to the exchange of information in automatic telecommunications operation. It is classified into four basic functions namely supervision, address, call progress and network management. Supervision signaling is used to bring up a call request on lines. Address signaling conveys information such as subscribers telephone number. Audible tones are usually referred as call progress signals. Network management signals are used to control bulk assignment of circuits.

Chapter 9 can be used as a source of experiments, projects and applications. Projects have been implemented on the floating-point C30 and C31 processors as well as on the fixed-point TMS320C25. They range in topics from communications and controls, to neural networks and can be used as a source of ideas to implement other projects. [ABSTRACT FROM PUBLISHER]

Chapter 3 covers the architecture and the instructions available for the TMS320C6x processor. Special instructions and assembler directives that are useful in DSP are discussed. Programming examples using C, assembly, and linear assembly are included in this chapter. [ABSTRACT FROM PUBLISHER]

This article presents information on the security of telephone systems. In many countries of the modern era, telephone tapping has become such a national pastime that even the general public are guarded about their telephone conversations. In other places, there are strict controls about personal privacy, which make it somewhat more difficult for an agency to monitor private telephone lines. some of those methods. It discusses the specific threats, the technology involved in the public switched telephone network and satellite communications, the solutions and technology available and, finally, the different applications. Electro-magnetic compatibility or transient electromagnetic pulse emanation standard attack on radiated information from a commercial telephone, which can be considered as another form of bugging. Secure telephones should offer resistance against physical tampering attempting to gain access to security parameters such as keys and algorithms.

This chapter explores the evolution from circuit switched based computer telephony integration in call centres to the logical conclusion of an all IP call centre. [ABSTRACT FROM PUBLISHER]

This chapter is in two parts. The first part explores the evolution of the current telephony network and its core component the 'circuit switch'. The second part explores the underlying messages that are used to connect calls across the circuit switched network, namely Signalling System number 7. [ABSTRACT FROM PUBLISHER]

Chapter twenty presents a prototype multi-agent system called Victor which is aimed at assessing and predicting faults in network elements that affect global virtual connections (VCs) with ATM, frame relay and IP service configurations. Victor relies on distributed and collaborative intelligent processing agents to associate, correlate and combine knowledge and information from multiple operations databases. The fault assessment component of Victor advises network operations personnel on specific actions to fix faults affecting specific VCs. The predictive fault management component of Victor anticipates potential degradations of network elements, such as switches, cards and trunks. [ABSTRACT FROM PUBLISHER]

Describes user concerns with how fast connections through a telecommunications service are set up. Distinguishes circuit-switched and packet-switched services. Defines the generic measure for circuit-switched services to be Post-Dial Delay (PDD), but recommends that quantification and evaluation be based on distributions of repeated measurements of PDD, rather than averages. Describes in detail how PDD is generated, showing every relevant element of delay introduced by the signaling system, together with the associated quantifiers of intrinsic QoS. Notes additional factors that must be considered for packet-switched services. Provides guidelines for interpreting distributions of delays to evaluate QoS with respect to routing speed. [ABSTRACT FROM PUBLISHER]

Of concern in this chapter are the following points: (1) What services are available on the public switched telecommunication network (PSTN) for the data end user? (2) How, and to what extent, will the PSTN degrade our data signal? (This includes other "degradations" such as loss of traffic, out-of-sequence delivery, and so on); and (3) What limitations are there in data rate and speed of service? [ABSTRACT FROM PUBLISHER]

Chapter 3 covers the fundamentals of input-buffered switches, including the head-of-line blocking phenomenon, traffic models and related throughput results, methods for performance improving, and scheduling algorithms. We show the problems of input-buffered switches, and present the techniques and algorithms that have been proposed to tackle the problems. [ABSTRACT FROM PUBLISHER]

Chapter 5 covers the banyan-family switches, including the self-routing properties, the non-blocking condition and how to realize it with the Batcher-sorting network, the output contention resolution algorithms (the three-phase algorithm and the ring reservation algorithm), and the parallel-banyan based Sunshine switch. It also covers other novel banyan-related switch designs, including tandem-banyan switch and shuffle-exchange switch with deflection routing, and the multicast copy networks and their principles. [ABSTRACT FROM PUBLISHER]

Chapter 9 presents an input-output-buffered switch, called a tandem-crosspoint (TDXP) switch, that fully utilizes current CMOS technologies. It starts with a brief review of basic input and output buffered switch architectures, and then describes the TDXP switch architecture and its performance. The switch supports unicast and multicast traffic. [ABSTRACT FROM PUBLISHER]

Chapter 6 covers numerous switch designs based on the knockout principle, including knockout switch, the concentration principle, construction of concentrators, channel grouping and the generalized knockout principle, the two-stage multicast output buffered ATM switch (MOBAS) and the multicast knockout principle, and a fault-tolerant multicast output-buffered ATM switch. [ABSTRACT FROM PUBLISHER]

Chapter 11 covers the optical packet switch architectures in both all-optical and optoelectronic approaches. The former stores packets in the optical domain while the latter in electrical domain. The strength and weakness of different architectures are presented. Two optical packet switches are described in detail to better understand switching operations and implementation complexity. [ABSTRACT FROM PUBLISHER]

Chapter 8 describes several crosspoint-buffered switches, where each crosspoint has a buffer. It presents a scalable-distributed-arbitration (SDA) switch to avoid the bottleneck of the arbitration time, and an extended version of the SDA switch to support multiple quality-of-service (QoS) classes. [ABSTRACT FROM PUBLISHER]

Chapter 7 focuses on the abacus switch, a scalable multicast switch architecture consisting of multicast grouping networks and small switch modules. It covers the switch architectures, arbitration algorithms, implementations, performances, and two extension designs based on the abacus switch. [ABSTRACT FROM PUBLISHER]

This chapter covers GSM data communication and networking. It includes: Overview and the reference configuration for data transmission in GSM; Principles for service selection at network transitions; Bit rate adaptation; Asynchronous data services (transparent and non-transparent transmission, asynchronous-synchronous conversion, PAD access to public packet-switched networks) Synchronous data services (overview, X.25 access); Fax transmission [ABSTRACT FROM PUBLISHER]

Chapter 2 presents spreading sequences of three different types: Orthogonal, Pseudo-Orthogonal and Quasi-Orthogonal. Several methods have been used for generating orthogonal Hadamard sequences of all sizes up to 256. Extended, complex and poly-phase Hadamard orthogonal codes are presented with their applications in CDMA. Also, the properties and designs methods for Pseudo-Orthogonal and Quasi-Orthogonal sequences are included. All the above types of sequences are analyzed and compared in terms of their synchronization timing-jitter properties. [ABSTRACT FROM PUBLISHER]

Chapter 3 presents the concept of switched CDMA networks. Such networks include the base station switched CDMA (BS/CDMA), the cable switched CDMA (CS/CDMA) and the satellite switched CDMA (SS/CDMA). Among these networks, the SS/CDMA has been described in detail in terms of its system architecture and operation. The SS/CDMA network has the capability of on board routing and is used to provide direct to end-user communication. [ABSTRACT FROM PUBLISHER]

Chapter 5 presents a demand assignment system for joint access and switching in the SS/CDMA network. It evaluates its throughput performance for integrated packet and circuit switched traffic under the control of optimum and random switching algorithms. Performance results are compared with the corresponding cases of SS/TDMA. Algorithms for optimum, sub-optimum and random switch scheduling have also been presented. [ABSTRACT FROM PUBLISHER]

Chapter 4 introduces the method of code division switching for routing calls and packets at the exchange node of the network. The Code Division Switch (CDS) can route the user data if they are in CDMA or TDMA form at a network node. Code division switch (CDS) architectures for satellite and terrestrial applications are presented, and their complexity is evaluated and compared with traditional switching techniques. [ABSTRACT FROM PUBLISHER]

The article presents information about the January 1, 2004 issue of the journal CDMA: Access and Switching. Code division may be considered as a generalized method for access and switching in communication networks. Such an approach may be viewed as a user encoding process where the choices of the code and spreading types can create a large set of access and switching techniques in which the traditional ones are included. In this sense, code division can provide a unified approach for multiple access and switching in communications.

This chapter is mainly about electronic prototyping and the reduction of a working prototype to a working PC board, with specific application to high frequency, high dynamic range, mixed signal circuitry. The author discusses laying circuits out intelligently, calculating the circuit board strays, assembling breadboards, and tuning LC filters. [ABSTRACT FROM PUBLISHER]

This article presents a list of several publications related to adaptive filtering and change detection. Some of those include "On State Estimation in Switching Environments," by G.A. Ackerson and K.S. Fu published in the journal "IEEE Transactions on Antornatic Control," Posterior Bayes Factors," M. Aitken, published in the "Journal of the Royal Statistical Society," and "Sequential Coding Algorithms: A Survey and Cost Analysis," by J.B. Anderson and S. Mohan, published in the journal "IEEE Transactions on Communications."

This chapter describes the joint application of two soft computing methods, evolutionary algorithms and fuzzy reasoning, to the problem of adaptive distributed routing control in packet-switched communication networks. In this problem, a collection of geographically distributed routing nodes are required to adaptively route data packets so as to minimize mean network packet delay. Nodes reach routing decisions locally using state measurements which are delayed and necessarily only available at discrete sampling intervals.

This chapter has developed the idea of separating the telecommunications network into a switched information subnet and a signalling subnet and has shown how this allows intelligence to be added to the signalling subnet. This fulfils the original promise of stored programme control and in effect puts the operator back into the network: after all, the most intelligent network technology ever deployed was the human operator sitting at a manual switchboard. [ABSTRACT FROM PUBLISHER]

This article presents information about video telephony. With the recent advances in modem technology and audio and video compression, real-time transmission of video and audio over the telephone network, also known as general switched telephone network or Public Switched Telephone Network, is possible. Modern voice compression techniques allow the transmission of speech at a rate of about 6-8 kbits/s with a quality that is comparable to that of 64 kbits/s pulse code modulation which is used in standard digital telephone networks.

The article discusses the concept of universal adaptive control by considering a simple class of scalar systems and also motivates the use of switching functions for this class. An alternative to the Nussbaum functions, that arise naturally in the feedback law if the sign of the high-frequency gain of the system to be stabilized is unknown, are considered. Switching functions and unbounded switching functions are discusses. The paper then gives a brief overview of how the switching functions described in the study are related and used to solve the universal adaptive control problem for different classes of systems.

The article presents information on vacuum-type metal-clad switchgear. Switchgear is generally considered to be switching and interrupting equipment that is normally equipped with controls, instruments, metering, protective, or regulating devices. It is primarily employed in electric power distribution systems in connection with the generation, transmission, and distribution, of power. A switchgear assembly is completely enclosed with 11-gauge sheet metal, except for ventilating openings and inspection windows. It contains a high-voltage section that includes primary circuit switching or interrupting devices or both, with buses and connections.

The article presents information on switched-capacitor (SC) networks. SC circuits consist of switches, capacitors and operational amplifiers (op amps). They are described by difference equations in contrast to differential equations for continuous-time circuits. Concurrently the mathematical operator to handle sample-data systems, such as switched-capacitor circuits is the z-transform and the Laplace transform for continuous-time circuits. The fundamental building blocks in SC circuits are voltage-gain amplifiers, sample/holds integrators and multipliers. A combination of these blocks is interconnected to yield a number of useful circuits.

The article presents information on sequential circuits. Logic circuits are classified into combinational and sequential circuits. A sequential circuit is made of combinational circuits and memories, and some inputs to the combinational circuits are driven by the outside signal and the rest by the memory outputs. The delay device used instead of the controllable memory device is generally called a delay line. In spite of the name, the traditional LC or the acoustic-delay lines are not used anymore.

This article reports that a photothyristor can be broadly defined as a thyristor capable of optically controlled switching. Other names used for photothyristors include optical thyristor and optothyristor. Depending on the detailed design and application, a photothyristor, when switched on, may emit light either spontaneously or in response to a stimulus. The basic structure of a thyristor is formed by four layers of alternatively doped pnpn semiconductors. A traditional thyristor generally has three terminals, called anode, cathode, and gate.

This article presents information on integrated services digital network (ISDN). ISDN has a digital nature and protocol architecture. ISDN-based secure transmission processing offers an excellent choice for industrial controls, teleconferencing, and distributed processing. Furthermore, several design and control environments require network-based virtual and design centers. This article also discusses the scope of digital switching with reference to data communications and networking, advanced bandwidth schemes, data security and encryption schemes, interconnectivity, and associated methodologies. Standard ISDN basic rate interface lines have 2 B-channels. ISDN primary rate interface uses four-wire T1 technology to provide reliable, high-speed switched connections to the public network.

This article presents information on interrupts, which are one solution to signaling asynchronous events to a host computer. The main evolutions in operating systems arose from different paradigms for sharing the machine. The key resource management policy in a multiprocessing system is the scheduling policy, used to decide which of the available processes will occupy the processor. Scheduling can be implemented in two forms, namely, nonpreemptive and preemptive. An interrupt vector is used to execute a hard clock interrupt routine, resulting in the currently executing process having its state saved and control passing to the clock service code. Event-signaling within the network subsystem between the hardware network interface device and the software device driver is typically accomplished via polling or device-generated interrupts.

This article presents information on electro-optical switches. The electro-optic switch is a specific case of the electro-optic modulator (EOM) that switches the optical power in a specific output channel between two discrete positions with the maximum and minimum transmission. Currently, the primary effort is aimed at improving the linearity of the transfer curve with concomitant suppression of nonlinear distortions, at broadening the bandwidth and lowering the drive power, and at minimizing crosstalk. From a practical viewpoint, simplification of the device design and associated fabrication process is also an important consideration.

This article presents information on direct current-direct current (dc-dc) power converters. High efficiency is invariably required, since cooling of inefficient power converters is difficult and expensive. This approach is also employed in applications involving alternating current, including high-efficiency dc-ac power converters, ac-ac power converters, and some ac-dc power converters. The power dissipated by the switch network is ideally equal to zero. When the switch contacts are closed, the voltage across the contacts is equal to zero and hence the power dissipation is zero.

The concept of quantum-mechanical tunneling of a particle through a potential barrier was known already in the 1920s. The discovery of tunneling of electron pairs across a superconductor-insulator-superconductor (SIS) junction was made by Josephson in 1962 and experimentally confirmed first by Anderson and Rowell in 1963. The phenomenon of that the electron-pair tunneling may produce a dissipationless current which may flow at zero bias voltage opened not only a new chapter in solid-state physics, but also provided a wide variety of stimulating applications. In this chapter, we introduce the phenomenology of the Josephson effect, formulate the electrodynamics of the Josephson junctions, and outline some circuits of practical interest. Some electrodynamic analyses are given to superconducting quantum interference devices (SQUIDs). A brief discussion about the possible use of SQUIDs and about the physical limits of various switching technologies in comparison with the superconducting electronic technology is also provided at the end of this chapter. [ABSTRACT FROM PUBLISHER]

This chapter explains the principles of 'Signalling' - the means by which the telecommunications user indicates to a telecommunications network his desire to make a 'call'. The signalling allows him to indicate the intended destination of his 'call' or 'message' and the nature of the connection he requires. 'Signalling' within the network controls the set-up and clearing of the connection. [ABSTRACT FROM PUBLISHER]

Part 1 (chapters 1-9) covers the fundamental principles of telecommunications transmission theory and switching. It covers circuit switching (used mainly in telephone networks) and packet-switching (used mainly in data and IP [Internet protocol] -networks). [ABSTRACT FROM PUBLISHER]

The control of the routing of calls and connections (so-called 'traffic') across telecommunications networks is the most difficult but most important responsibility of a network operator. Only by careful planning and management of appropriate call and traffic routing plans can the network operator ensure successful connection of calls and the efficient use of network resources. This chapter discusses the techniques used by network operators in establishing efficient call routing patterns and the special problems caused by network interconnection and interworking, when calls or connections originated in one network have to be passed to another operator's network for completion. [ABSTRACT FROM PUBLISHER]