Telecommunication Switching Research Articles

Characteristic's analysis of associative switching system

This paper introduced new method and model of telecommunication switching system design which can be applied to wavelength-division multiplexing (WDM) optical networks, circuit-switching networks or virtual channel/path connections in an asynchronous transfer mode (ATM) networks. Modern data switching systems such as electronic private branch exchange (PBX), routers and switches include switching matrix which are constructed in the form of bipartite graphs. In such systems, the issues of requests’ processing are considered from the queuing theory point of view. Associative switching systems are fundamentally new structures, therefore it is necessary to develop adequate methods for their throughput determination. Article covered matters of throughput determination basics of an associative switching system and the obtained formulas used for state probability calculation of switching modules and system throughput.

Model-Based Diagnosis of Telecommunication Cooling Systems Malfunctioning

A model is developed that allows simulating the most-likely failures possibly occurring in freecooling (FC) systems of telecommunication (TLC) switching rooms. Main aim is to provide an effective and online implementable diagnosis method, which in turn will allow fulfilling the threefold function of safeguarding electronic equipment, ensuring desired air quality in case of human presence and reducing malfunction-related waste of energy. Specifically in this work, obstruction (reduction of the volumetric flow of air introduced into the room) and loss of efficiency (degradation of the fan) are deepened. Two black-box sub-models were developed to simulate the above described faulty functioning of the free-coolers. Subsequently, the fault signature matrix was developed, through which the “symptoms”, calculated as residuals between the “faulty” and “non faulty” conditions of the monitored variables, are associated to the corresponding faults. The peculiarity of the telecommunication sector, where nowadays data acquisition and monitoring platforms are significantly spreading to monitor most significant energy consumptions, including cooling loads, was proved essential in guaranteeing effective isolation of different faults. The simulation results highlight the reliability of the developed diagnostic tool, expected to be versatile and easy to implement enough for being extended to air-handling unit diagnosis, as well as other industrial sectors.

Programmable Spectral Filter in C-Band Based on Digital Micromirror Device.

Optical filters have been adopted in many applications such as reconfigurable telecommunication switches, tunable lasers and spectral imaging. However, most of commercialized filters based on a micro-electrical-mechanical system (MEMS) only provide a minimum bandwidth of 25 GHz in telecom so far. In this work, the programmable filter based on a digital micromirror device (DMD) experimentally demonstrated a minimum bandwidth of 12.5 GHz in C-band that matched the grid width of the International Telecommunication Union (ITU) G.694.1 standard. It was capable of filtering multiple wavebands simultaneously and flexibly by remotely uploading binary holograms onto the DMD. The number of channels and the center wavelength could be adjusted independently, as well as the channel bandwidth and the output power. The center wavelength tuning resolution of this filter achieved 0.033 nm and the insertion loss was about 10 dB across the entire C-band. Since the DMD had a high power handling capability (25 KW/cm2) of around 200 times that of the liquid crystal on silicon (LCoS) chip, the DMD-based filters are expected to be applied in high power situations.

Design and FPGA Synthesis of Three Stage Telecommunication Switching in HDL Environment

Abstract Telecommunication networks are based on crossbar switching structure. Non-blocking crossbar switching structure is used crosspoint switch fabric ICs. High performance non-blocking matrixes cross point switches are use to avoid the congested path to the output, and eliminate the bandwidth problem of one at a time. Telecommunication switching uses multistage crossbar switching to overcome the limitations of individual chips or boards. The research paper focuses on the FPGA implementation of 64 × 64 three stage telecommunication switching. The generic architecture scheme is followed to implement 64 × 64 three stage network configuration, with 64 inlets and 64 outlets as cluster size. The design is developed with the help of Xilinx ISE 14.2, software, synthesized on Virtex- 5 FPGA, and function simulation is carried out in Modelsim 10.1b student edition. Very High Speed Integrated Circuit Hardware Description Language (VHDL) is used to develop the design.

Measuring knowledge persistence: a genetic approach to patent citation networks

The aim of this paper is to propose a new empirical method for identifying technologically important patents within a patent citation network and to apply it to the telecommunication switching industry. The method proposed is labelled the genetic approach, as it is inspired by population genetics: as geneticists are interested in studying patterns of migration and therefore the common origins of people, in innovation studies we are interested in tracing the origin and the evolution of today knowledge. In the context of patent and citation networks, this is done by calculating the patent’s persistence index, i.e., decomposing patent’s knowledge applying the Mendelian law of gene inheritance. This draws on the idea that the more a patent is related (through citations) to “descendent” patents, the more it affects future technological development and therefore its contribution persists in the technology. Results show that the method proposed is successful in reducing the number of both nodes and links considered. Furthermore, our method is indeed successful in identifying technological discontinuities where previous knowledge is not relevant for current technological development.

Digital micromirror device as a diffractive reconfigurable optical switch for telecommunication

Digital micromirror devices (DMDs) by their high-switching speed, stability, and repeatability are promising devices for fast, reconfigurable telecommunication switches. However, their binary mirror orientation is an issue for conventional redirection of a large number of incoming ports to a similarly large number of output fibers, like with analog micro-opto electro-mechanical systems. We are presenting here the use of the DMD as a diffraction-based optical switch, where Fourier diffraction patterns are used to steer the incoming beams to any output configuration. Fourier diffraction patterns are computer-generated holograms that structure the incoming light into any shape in the output plane. This way, the light from any fiber can be redirected to any position in the output plane. The incoming light can also be split to any positions in the output plane. This technique has the potential to make an “any-to-any,” true nonblocking, optical switch with high-port count, solving some of the problems of the present technology.

Disaster-resilient networking: a new vision based on movable and deployable resource units

During the great east Japan earthquake on March 11, 2011, a lot of ICT resources - telecom switching offices, optical fiber links, and so forth - were completely or partially damaged due to the tremor and the resultant tsunami. As a consequence, the demand for ICT services explosively increased, mainly because the people of the affected areas were trying desperately to communicate with the outside world that led to a phenomenal rise in the network traffic. In the Nippon Telegraph and Telephone (NTT) East Corporation alone, 385 telephone offices stopped operating immediately following the earthquake because of power outages and disruption of facilities. Approximately 1.5 million users were cut off from using fixed-line telephone service. The demand for fixed-line and mobile telephone services jumped up to 10-50 times the usual. This gave rise to serious traffic congestion, and the emergency ICT networks and services could not deal with this issue sufficiently. This article proposes a network architecture that is resilient even through devastating disasters by effectively exploiting specially designed movable and deployable resource units, which we refer to as MDRUs. An MDRU having the ability to accommodate communication and information processing functions can be rapidly transported or moved to the disaster zone, and can be deployed within a reasonably short time to establish the network at the disaster site and launch ICT services. The concept and configuration of the network architecture based on the MDRU and its features are described in this article. Some preliminary simulation results are also reported to evaluate the performance of our adopted MDRU-based disaster resilient network.

Deriving Vehicle Speeds From Standard Statistics of Mobile Telecom Switches

Telematics typically utilizes vehicle detectors and Global Positioning System (GPS)-based vehicle probes to compute the speeds of vehicles. When the detectors and the GPS probes are not available, vehicle speeds can be estimated by the cellular floating vehicle data technique, where the telecom network needs to spend extra effort to identify specific users and track their movements. This paper proposes the Speed Determination (SD) Algorithm, which uses standard statistics of telecom switches to compute the speeds of vehicles without extra effort in the telecom network. Simulation and field measurements indicate that the SD Algorithm can effectively report the vehicle speeds of two-way roads.

Application of the fractional Fourier transform to the design of LCOS based optical interconnects and fiber switches

It is shown that reflective liquid crystal on silicon (LCOS) spatial light modulator (SLM) based interconnects or fiber switches that use defocus to reduce crosstalk can be evaluated and optimized using a fractional Fourier transform if certain optical symmetry conditions are met. Theoretically the maximum allowable linear hologram phase error compared to a Fourier switch is increased by a factor of six before the target crosstalk for telecom applications of -40 dB is exceeded. A Gerchberg-Saxton algorithm incorporating a fractional Fourier transform modified for use with a reflective LCOS SLM is used to optimize multi-casting holograms in a prototype telecom switch. Experiments are in close agreement to predicted performance.

Data Stream Management System and Capital Market Surveillance

Importance of real-time data analysis has been felt since early '90s and thus processing of streaming data (from either sensor networks or telecom switches or web and other disparate systems) is the demand of the industries worldwide. Quicker detection of fraudulent activities in a financial system is the order of the day. Thus capital market surveillance, if can be performed by using the streaming input of various trading transactions, without being stored, that would be beneficial to the regulatory authorities and stock exchanges. In this paper, we describe how stream processing using a data stream management system (DSMS) can be used for the above task and how effective would be that in terms of performance and latency. We present results obtained from using a commercial event stream processing system (IBM InfoSphere Streams platform) for certain typical fraud detection scenarios.

Multinational corporations, inter-organizational networks and subsidiary charter removals

This paper provides insights into the dynamics of a charter removal at a Hungarian subsidiary of the Siemens telecommunication switching division. By using inter-organizational network theory, we investigate how host-country factor endowments, the resource position of a subsidiary and the density of network exchange relationships within the organizational network influence the removal of a multinational corporate subsidiary's charter. The dispersion of resources in a multinational corporation drives intra-firm competition, which will typically lead to the removal of a subsidiary's charter if the subsidiary lacks specialized resources – typically an outcome of host country comparative disadvantages – and simultaneously holds a position on the periphery of the organizational network.

A model for simulation and optimal energy management of Telecom switching plants

The paper reports on the research activities the authors recently started with the aim of improving energy management in Telecom switching plants. Main objective of the research is to minimize the energy consumption associated to room climate control (CC). Specifically in this work, a model of room thermal dynamics was developed. In order to achieve a satisfactory compromise between accuracy, experimental burden and computational time, a grey-box approach was adopted. A lumped capacity description of a selected telecommunication (TLC) equipment room was performed, by applying the first principle of Thermodynamics to a control volume including: walls; TLC equipment; air filling the room; CC system, which mainly consists of free-coolers (FC) and refrigeration units (RU). Therefore, room temperature variation is estimated as function of heat released by TLC equipment, air moved by free-coolers, cold air supplied by the refrigeration units and heat exchange with the surroundings. Model generalization, performed comparing simulations with real measurements, highlighted the very good accuracy guaranteed by the modeling methodology proposed in the paper. Moreover, the relative simplicity and limited number of unknown parameters suggest using the model in optimization analyses aimed at minimizing CC-related energy consumption for a variety of TLC switching plants. Preliminary model-based scenario analyses were carried-out, showing that improved CC system management may result in energy savings as high as 25%.

Vital Nodes, Interconnected Infrastructures, and the Geographies of Network Survivability

With an increased level of interconnection between critical network infrastructures, the potential for cascading actions that trigger both primary and secondary network failures are of great concern. Recent events, including the 2001 attacks on the World Trade Center, the blackout of 14 August 2003, and the Galaxy IV satellite failure in 1998, have reinforced the need for a more thorough understanding of vulnerabilities relative to system performance. This article explores the topological complexities associated with network interconnections. In particular, we evaluate the potential impacts of losing critical infrastructure elements that are geographically linked. The loss of vital nodes, like telecommunication switching centers, is evaluated utilizing a developed spatial optimization model. Results indicate that certain infrastructure topologies are not particularly well equipped to handle the loss of vital nodes, whereas others could withstand the loss of such nodes and maintain an adequate level of service.

USING INPUT INVARIANCE AS A METHOD TO FACILITATE SYSTEM DESIGN IN DPS APPLICATIONS

Distributed power supply (DPS) systems are extensively used to supply different electronic equipment and systems such as telecom switching systems. Continuous reduction of supply voltages of digital integrated circuits from the previous industry standard of 5 V down to 1 V or even less has necessitated the use of point-of-load system architectures due to high supply currents. The input currents of the switched-mode power supplies contain typically high ripple currents necessitating the use of noise suppression (EMI) filters to meet the stringent requirements stipulated by international standards. The interactions between the load converters, EMI filters, and supply side converters may adversely affect the stability and performance of the system. The system analysis is typically made based on the behavior of the ratio between the output impedance of the supply side and the input impedance of the load side known as minor-loop gain. Certain forbidden regions in the complex plane have been developed out of which the minor-loop gain should stay in order to guarantee stability. Even if the restrictions for the behavior of the minor-loop gain are well-defined, the accurate prediction of the associated impedances is difficult or even impossible. We propose, in this paper, a method based on input invariance to cancel the load-side interactions in the small-signal sense. The only concern left is then the stability of EMI filters, which may be considered based on the input power of the associated converters.

Good things, small packages [microelectromechanical systems

While semiconductor chip manufacturers still suffer from the recent downturn, the future looks a little brighter for microelectromechanical systems (MEMS). Also called microsystems and micromachines, these devices are found in many diverse applications, such as air bag sensors, ink-jet heads, medical sensors and telecommunication switches. MEMS can be manufactured from a variety of materials using a variety of processes in a variety of steps. For the foundry industries, it creates problems because each process can only be used for one customer. Because of their application-specific nature, MEMS devices often have to be designed using proprietary manufacturing processes that are specific to one manufacturing facility. In this paper, the author examined the surrounding issues in manufacturing MEMS as well as the probable solutions hypothesized by different experts.

Generic Model and Analysis of Asymmetric Spanke Optical Switch Configuration

Spanke switch architecture is predominantly used in telecommunication switching circuits. In this architecture the number of inlets is equal to the number of outlets (symmetric type). However, some applications require unequal number of inlets and outlets (asymmetric type). No model is available to characterize the parameters of the asymmetric configuration. This paper analyses the parameters of asymmetric Spanke optical switch configuration. The analysis has been done for the number of switch elements, number of crossovers, maximum loss and minimum loss. Also their corresponding behaviors are obtained. A comparison has been made between asymmetrical and symmetrical configurations. The proposed analysis model can be used for both types of Spanke configurations to get optimal number of switch elements and crossovers.

Simulations Based Design for a Large Displacement Electrostatically Actuated Microrelay

An electrostatically actuated microrelay with large displacement, small actuation voltage and limited plate surface dimensions is designed to meet stringent telecommunication switching requirements. Fabrication feasibility and performance characteristics of the device are evaluated using a commercial CAD for MEMS tool. Simulation results of the device performance including pull-in voltages for different suspension stiffness variations, natural frequencies, stresses and restoring forces are presented.

The myth of market dominance: telecommunication manufacturing in Poland, Hungary and the Czech Republic — a case study

The paper discusses the impact of Western manufacturers on competition and innovation in the telecommunication sector in Hungary, Poland and the Czech Republic. It examines the issue of market dominance by shedding some light on the industrial history, the current evolution and market structure of telecommunication equipment industry in these countries. In using case study evidence, the paper demonstrates that the contribution of Western manufacturers has been important to the accumulation of firm specific assets and sectoral growth of the telecommunication switching industry in CEE countries. It concludes that an involvement of competition authorities in the telecommunication switching market or strict imposition of procurement initiatives of the European Union does not seem desirable for the time being. Furthermore, there are serious threats to local telecommunication manufacturing in CEE countries if current EU procurement policies are imposed.

Learning from Technology Transfer in the Greek Context: The Case of Digital Telecommunication Switches

This paper examines the process of technology transfer and associated learning effects experienced by the Greek telecommunication equipment manufacturer INTRAKOM as a result of its involvement in public procurement processes and the technological shift towards software-driven digital switching and transmission systems. Drawing upon the role of Government procurement as an instrument for industrial policy and the learning potential of a technology transfer process, the paper argues that the Public sector's industrial policy considerations, exercised through the procurement practices of the Greek Public Telecommunication Operator (OTE), as well as INTRAKOM's own timely focus in establishing a long-term collaboration agreement with a leading international vendor (ERICSSON) played a catalytic role in the accumulation of domestic capabilities in the manufacturing of selected telecommunication equipment products.

An algorithm that uses forward planning to expedite conflict-free traffic assignment in time-multiplex switching systems

In multichannel telecommunication networks, switching systems, and processor-memory interconnects, the need for conflict-free traffic assignment arises whenever packets (or requests) are to be directed from input buffers (processors) to specific outlets (modules). This paper presents an algorithm, based on forward planning, which can be used in the above-mentioned applications for scheduling conflict-free transfers of packets from inputs to outputs. The performance of the algorithm is evaluated in the sense of throughput and delay and is compared with that of system of distinct representatives (SDR), an earlier proposed algorithm featuring 100% assignment efficiency. Then, its worst-case computational complexity is compared with that of SDR and several suboptimal (but low complexity) algorithms reported in literature. The proposed forward planning algorithm is shown to have the lowest order of computational complexity and permits simpler buffer organization and access modes. Moreover, it is shown that forward planning of packet transmissions offers significant performance improvements if the finite capacity of buffers is taken into account.