Showing papers by "Deutsche Telekom published in 1999"

Any network, any terminal, anywhere [cellular radio]

Abstract: In light of the current technology trends in the area of applications, wireless networks, and terminals, this article isolates a number of design requirements of future advanced mobile systems. We discuss research and standardization activities in the area of service support platforms and their corresponding application programming interfaces (API), where we especially focus on the wireless application protocol (WAP), Mobile Station Execution Environment (MExE), and HTTP-NG as candidates for the provision of mobile Internet services in cellular networks.

Application of amplitude histograms to monitor performance of optical channels

Abstract: A novel method for performance monitoring of transparent optical systems, based on the evaluation of amplitude histograms generated by asynchronous sampling, is investigated experimentally. The method was found to detect signal degradations due to noise, crosstalk or pulse distortion with a high sensitivity.

Combining digital watermarks and collusion-secure fingerprints for digital images

Abstract: Digital watermarking is the enabling technology to prove ownership on copyrighted material, detect originators of illegally made copies, monitor the usage of the copyrighted multimedia data and analyze the spread spectrum of the data over networks and servers. Embedding of unique customer identification as a watermark into data is called fingerprinting to identify illegal copies of documents. Basically, watermarks embedded into multimedia data for enforcing copyrights must uniquely identify the data and must be difficult to remove, even after various media transformation processes. Digital fingerprinting raises the additional problem that we produce different copies for each customer. Attackers can compare several fingerprinted copies to find and destroy the embedded identification string by altering the data in those places where a difference was detected. In our paper we present a technology for combining a collusion-secure fingerprinting scheme based on finite geometries and a watermarking mechanism with special marking points for digital images. The only marking positions the pirates can not detect are those positions which contain the same letter in all the compared documents, called intersection of different fingerprints. The proposed technology for a maximal number d of pirates, puts enough information in the intersection of up to d fingerprints to uniquely identify all the pirates.

10 Gbit/s all-optical Boolean XOR with SOA fibre Sagnac gate

Abstract: All-optical Boolean XOR logic is demonstrated with a three terminal fibre Sagnac interferometer employing a semiconductor optical amplifier. Full duty cycle operation at 10 GHz is shown and low pattern dependence has been achieved on a pseudo-data pattern at 10 Gbit/s with low switching energy.

Electronic identification tag

Abstract: The invention relates to an electronic identification tag or card which is provided with a rated breaking point (7) which is configured in a vertical, diagonal, undulating, zig-zag, meandering or any other manner. The electronic identification tag or card comprises two parts which are normally configured as a mirror image and in which identical data are stored in an identical manner. Integrated, embedded or implanted memory or microprocessor chips (4 and 4') have the same structure and a part of the identification tag or card is provided with holes (5) for a neck chain. In addition, visually legible data are incorporated into both parts, such as a personal identification number (PKZ) and the blood group (A Rh+), nationality and name (NN). The electronic identification tag or card consists of a highly resistant plastic material, glass, ceramics or a similar material and the data storage medium or data memory are embedded with our without intelligent device in the form of a chip, magnetic strip or hologram. The identification tag or card is equipped in such a manner that it can enter into communication, either via a contact element or wireless, with a data processing system or non-contacting readout devices. The memory or microprocessor structure allows for a highly flexible directory structure. For example, in the main memory directory global card data such as the personal identification number (PKZ), nationality (N), name (N) and blood group (A Rh+) can be stored, while in data fields of the main directory access authorizations can be stored and, for example, the training or special skills of a person wearing the tag can be written into the sub-directories.

Synchronization for systems with antenna diversity

Abstract: This paper deals with the synchronization of systems with frequency domain signal processing and antenna diversity. The results can be applied for both, single carrier transmission with frequency domain equalization (FDE) and orthogonal frequency division multiplexing (OFDM). For the considered systems, carrier frequency and temporal position of the FFT (fast Fourier transform) window have to be synchronized. A synchronization concept for systems with antenna diversity is presented which uses one pilot FFT symbol per transmission frame. The pilot FFT symbol consists of two periods of a chirp signal.

Method for co-channel interference cancellation in a multicarrier communication system

Abstract: A method for cancelling co-channel interference in a multi-carrier communication system includes receiving a serial baseband multi-carrier signal including at least one desired signal and at least one interference signal over at least one receiving branch, and converting the received multi-carrier signal into a plurality of baseband sub-carrier signals. Co-channel interference in each sub-carrier signal is cancelled by subtracting an estimated desired received sub-carrier signal and an estimated interference sub-carrier signal from a received sub-carrier signal. The sub-carrier signals are converted to a multi-carrier output signal comprising the desired signal.

A 16, 24, 32 kbit/s wideband speech codec based on ATCELP

Abstract: This paper describes a combined adaptive transform codec (ATC) and code-excited linear prediction (CELP) algorithm, called ATCELP, for the compression of wideband (7 kHz) signals. The CELP algorithm applies mainly to speech, whereas the ATC mode is selected for music and noise signals. We propose a switching scheme between CELP and ATC mode and describe a frame erasure concealment technique. Subjective listening tests have shown that the ATCELP codec at bit rates of 16, 24 and 32 kbit/s achieved performances close to those of the CCITT G.722 at 48, 56 and 64 kbit/s, respectively, at most operating conditions.

RZ versus NRZ modulation format for dispersion compensated SMF-based 10-Gb/s transmission with more than 100-km amplifier spacing

Abstract: We compared numerically and experimentally the transmission behavior of return-to-zero (RZ) and nonreturn-to-zero (NRZ) modulated signals, 10 Gb/s were transmitted over 2040-km standard single-mode fiber using an alternating dispersion compensation scheme in a recirculating loop with 102 km amplifier spacing. Receiver sensitivities of -33 dBm (NRZ) and -35 dBm (RZ) could be achieved. RZ allows for a simple linear dispersion compensation whereas NRZ suffers from nonlinear signal distortion. NRZ requires under-compensation of the linear chromatic dispersion dependent on signal power and transmission length. Therefore, NRZ makes network design more difficult.

Model Scenarios for Direction-Selective Adaptive Antennas in Cellular Mobile Communication Systems – Scanning the Literature

Abstract: Intelligent antennas offer the possibility of greatly increasing the capacity of cellular mobile radio systems. We give a comprehensive overview of the literature concerning model scenarios for applications of direction-selective intelligent antennas. Measurement campaigns and simplified models are described that have been derived from these measurements or from physical considerations. Furthermore, directional fading simulators are reviewed which are essential for testing of smart antenna systems.

40 Gb/s and 4/spl times/40 Gb/s TDM/WDM standard fiber transmission

Abstract: We investigate the possibilities of 40 and 4/spl times/40 Gb/s time division multiplexing wavelength division multiplexing (TDM/WDM) return-to-zero (RZ) transmission over embedded standard single-mode fibers (SMF) at a transmission wavelength of 1.55 /spl mu/m both experimentally and theoretically. Dispersion of the SMF is compensated by a dispersion compensating fiber (DCF). Transmission over a span of 150 km of SMF in the single-channel case and of 100 km SMF in the multichannel case are reported. Numerical calculations are employed to investigate the possibility of cascading the spans both for single-channel and multichannel transmission. For single-channel transmission, it is shown that optimum performance is achieved with postcompensation of the DCF. The input power at the SMF and DCF input have to be chosen carefully. For four channel transmission, the performance is mainly limited by residual dispersion in the outermost wavelength channels. It is shown numerically that improvement is achieved by employing the newest type DCF which also compensates the dispersion slope of the SMF. For a WDM channel separation of 2 nm no significant additional degradation due to cross-phase modulation (XPM) or four-wave mixing is observed.

Federated Transaction Management with Snapshot Isolation

Abstract: Federated transaction management (also known as multidatabase transaction management in the literature) is needed to ensure the consistency of data that is distributed across multiple, largely autonomous, and possibly heterogeneous component databases and accessed by both global and local transactions. While the global atomicity of such transactions can be enforced by using a standardized commit protocol like XA or its CORBA counterpart OTS, global serializability is not self-guaranteed as the underlying component systems may use a variety of potentially incompatible local concurrency control protocols. The problem of how to achieve global serializability, by either constraining the component systems or implementing additional global protocols at the federation level, has been intensively studied in the literature, but did not have much impact on the practical side. A major deficiency of the prior work has been that it focused on the idealized correctness criterion of serializability and disregarded the subtle but important variations of SQL isolation levels supported by most commercial database systems. This paper reconsiders the problem of federated transaction management, more specifically its concurrency control issues, with particular focus on isolation levels used in practice, especially the popular snapshot isolation provided by Oracle. As pointed out in a SIGMOD 1995 paper by Berenson et al., a rigorous foundation for reasoning about such concurrency control features of commercial systems is sorely missing. The current paper aims to close this gap by developing a formal framework that allows us to reason about local and global transaction executions where some (or all) transactions are running under snapshot isolation. The paper derives criteria and practical protocols for guaranteeing global snapshot isolation at the federation level. It further generalizes the well-known ticket method to cope with combinations of isolation levels in a federated system.

Experimental comparison of 40 Gbit/s RZ and NRZ transmission over standard singlemode fibre

Abstract: 40 Gbit/s transmission experiments on standard fibre (16 ps/km/nm) and with > 100 km amplifier spacing demonstrate that transmission lengths of 432 km for RZ and 218 km for NRZ modulation schemes are possible, under comparable experimental conditions and in agreement with theoretical studies.

Method for generating a random number on a quantum-mechanical basis and random number generator

Abstract: The invention relates to a method for generating a random number on a quantum-mechanics basis and a random generator used notably for carrying out said method. The invention is based on the fundamentally random choice of path of a quantum particle on a beam splitter (8, 18), detectors (D1, D1', D2, D2') for capturing the particles being assigned to the outputs (11, 12, 16, 17) of the beam splitter (8, 18). The detectors or their counting events represent different number values of the random sequence. According to the invention, the generation of a multi-particle state in the output channel (11, 12, 16, 17) of the beam splitter (8, 18), and thus of several particles which impact on the detector (D1, D1', D2, D2'), significantly and advantageously increases the response probability of the detector and thus the probability of obtaining a useable counting event for every multi-particle state generated by the source (3, 3'). In this way a random sequence can be obtained more rapidly and more reliably than with single-particle detection.

System for monitoring wearers of protective respiratory equipment

Abstract: The invention relates to a system for monitoring wearers of protective respiratory equipment and to a mobile unit and a base station for using in a system of this type. The aim of the invention is to reduce the risks to wearers of protective respiratory equipment. To this end, system data are continually transmitted to a base station (20) by a mobile unit (21) which is fitted to a compressed air breathing apparatus (22) and which has a radio transmitter (60). The wearer of the protective respiratory equipment and a person monitoring them receive acoustic and/or visual alarm signals and warning signals according to the system data.

Simulator for simulating an intelligent network

Abstract: The invention relates to a simulator for simulating the performance of an intelligent network (IN), with the following components: 1. a module (201, 301, 401) for simulating any IN-typical runs (traffic simulator) in accordance with the rules of traffic theory; 2. a module (202, 302, 402) for event-oriented simulation of the service control point (SCP simulator) using process models; 3. elements (203, 204, 304-307, 406-409) for transferring data between the modules; 4. elements (207, 311, 416, 208-212, 312-317, 411-415) for inputting and storing the network configuration, communications service specification and other simulation parameters and transferring them to the relevant modules and 5. elements (205-207, 308-310, 417-420, 423) for outputting and/or storing the simulated data. Modules (303, 403, 503, 404, 502)for simulating the SS7 signalling system, preferably taking into consideration the functionalities of the service relay point (SRP) (103), and for simulating the overload defence mechanisms within the IN are also provided. The simulation models communicate with transfer files in a file mode or are linked by a common organisation programme, the on-line simulator, in an on-line mode. Central elements of the simulator in the on-line mode are event calendars in which events to be processed by the simulation modules are entered in the order in which they are processed and which enable processes which in reality are carried out in parallel to be processed in a sequence. The inventive IN simulator makes it possible to analyse the performance of an IN in its present or a future state in order to advantageously identify weak points and increase the efficiency of the IN.

Method and device for producing a choice of either single photons or pairs of photons in an optical channel

Abstract: The invention relates to a method for producing a choice of either single photons or pairs of photons in an optical channel (16, 17), comprising the following steps: establishing a two-photon state (photon pair); physically separating said photon pair and obtaining the quantum mechanical correlation in the event that the photons are emitted collinearly; coupling each photon into one optical channel (14, 14', 14') respectively, one channel (15, 15', 15') containing an interferometer (7-13) with a variable difference in optical paths δ1F-δ1S and the other channel containing an optical retardation route (19) of optical length δ1; physically bringing the two channels together with a beam splitter (18, 31-36); matching the values δ1F, δ1S and δ1 in such a way that the probability K of coincidences between the outputs (16, 17) of the beam splitter can be either approximately K=0 or approximately K=1 or approximately a predetermined intermediate value, K=0 corresponding to a photon pair in one of the output channels (16, 17) of the beam splitter and K=1 corresponding to two single photons in the two output channels of the beam splitter. The invention provides a means of producing an optical separating filter or gate for either single photons or photon pairs which can be used in quantum cryptography and as a basic element of a quantum optical calculating machine.

Method for co-channel interference cancelation in a multicarrier communication system

Abstract: The present invention relates to an interferance signal cancel ing method, a receiver using the same and a digital multi-carrier communication system comprising such a receiver. A main aspect of the present invention is to apply an interference cancellation scheme to a digital multi-carrier communication system. By using a digital multi-carrier communication system, the effect of the inter-symbol interference is avoided. As a result the receiver (8) comprises a plurality (L) of interference cancellers (171-17L) each of which is assocaiated to a respective one of sub-carrier signals for canceling only co-channel interference.

Chipkarte, insbesondere Guthabenkarte

Abstract: Die Erfindung betrifft eine Chipkarte, insbesondere Guthabenkarte, mit mindestens einem elektronischen Datentrager, in die eine optische Anzeige integriert ist, die ein Flachenleuchtkorper aus polymeren Material, insbesondere ein Anzeigeelement aus pLEDs ist. Mit der Erfindung ist es moglich, den Informationsstand des Datentragers unmittelbar, d. h. ohne externes Lesegerat auf der optischen Anzeige sichtbar zu machen. Hierzu wird beispielsweise fur eine benutzerdefinierte Zeitspanne ein Stromkreis durch einen Mikroschalter geschlossen. Uber einen Taster kann bei der Abfrage die Informationsabfolge gesteuert werden. Die Energieversorgung erfolgt durch ein Solarzellenmodul oder eine Primarbatterie. Daruber hinaus kann beispielsweise ein Kondensator als vorsorglicher Energiespeicher dienen.

Java Bytecode Verification by Model Checking

Abstract: Verification plays a central role in the security of Java bytecode: the Java bytecode verifier performs a static analysis to ensure that bytecode loaded over a network has certain security related properties. When this is the case, the bytecode can be efficiently interpreted without runtime security checks. Our research concerns the theoretical foundations of bytecode verification and alternative approaches to specifying and checking security properties. This is important as currently the “security policy” for Java bytecode is given informally by a natural language document [LY96] and the bytecode verifier itself is a closed system (part of the Java virtual machine). We believe that there are advantages to more formal approaches to security. A formal approach can disambiguate the current policy and provide a basis for verification tools. It can also help expose bugs or weaknesses that can corrupt Java security [MF97]. Moreover, when the formal specification is realized in a logic and verification is based on a theorem prover, extensions become possible such as integrating the verification of security properties with other kinds of verification, e.g., proof-carrying code [NL96,NL98].

Verfahren zur abrechnung von internet-dienstleistungen über mobilfunk

Abstract: Die Erfindung betrifft ein Verfahren zur Abrechnung von Internet-Dienstleistungen uber Mobilfunk. Ein Mobilfunkkunde bezahlt beim Surfen im Internet z. B. mittels eines WAP-fahigen Endgerats (Wireless Application Protocol) fur bestimmte Inhalte (Information, Datenbankrecherche, Fahrplanauskunft, Spiele, etc) jeweils einen geringen Einzelbetrag. Dieser kann erfindungsgemas uber das Mobilfunknetz effizient und sicher abgerechnet werden. Die fur eine Bezahltransaktion erforderlichen Kundendaten werden erfindungsgemas zentral in einer Datenbank eines Payment-Gateway gehalten. Der Kunde kann gegenuber dem Anbieter ein Guthaben authorisieren, von welchem der Anbieter die angefallenen Abrechnungsbetrage abbucht.

Quantum cryptography system for a secure transmission of random keys using a polarization setting method

Abstract: A quantum cryptography system using electrooptical liquid crystal modulators which change the polarization and which are designed as electrically rotatable retardation plates whose two birefringent axes are rotated by the applied electrical field around an angle θ which depends on the strength of this field A λ/2 retardation plate rotates the elliptically polarized light striking the plate around an angle 2θ at speeds in the microsecond range The quantum cryptography system can be used for interception-proof data transmission over transmission links that are accessible to the public

Using High-Level Petri Nets in the Field of Intelligent Networks

Abstract: Telecommunication systems in general, and hence Intelligent Networks too, are large distributed systems with a high degree of concurrency. To develop and investigate specific aspects of such systems, adequate formal specification techniques are needed. Motivated by a short historical overview of Petri net usage at our premises, we introduce the requirements we have to pose on a formal specification language. We present three selected applications of high-level Petri nets in the area of Intelligent Networks. They cover modelling aspects under a functional-oriented modularisation as well as within an object-oriented approach. Formal verification techniques are addressed additionally. Our experiences prove, that, on a technical level, high-level Petri nets are well suited to specify telecommunication systems and services. However, to enable their broader usage in the telecommunication area, still some hurdles have to be taken. We discuss some of them.

Single-mode optical fiber

Abstract: The invention relates to a single-mode low-dispersion optical fiber for wavelength division multiplexing (WDM) of an optical transmission link, comprising a central fiber core with a radius r1, two inner layers of cladding with an outer radius r2 or a, whereby a is greater than r2, and an outer layer of cladding, whereby the refractive index n(r) of the fibers is inconstant as a function of the fibre radius r (a triple clad fiber). A fiber with a low dispersion in the wavelength range of approximately 1400 - 1700 nm, i.e. in the third optical window, can be manufactured using conventional production methods by selecting the appropriate profile and refractive index differentials between the core and or cladding without increasing the attenuation of said fibers. The transmission quality and output of an optical transmission link is increased by the inventive fibers in comparison with other standard optical fibers.

Method of providing a dial-in function in telecommunication systems

Abstract: A method and a device are described for providing or simulating a direct dial-in function by providing an extension dialing function in telecommunication systems that have no direct dial-in capability with dedicated extension numbers. The dial-in capability is implemented in that an incoming call is automatically received by the TC system, the user is automatically prompted, via an audio user message, to input extension dialing commands, these extension dialing commands are automatically assigned to an extension and with this assignment information an electronic forwarding signal is generated, which causes the TC system to switch the incoming connection to an extension. This forwarding signal simulates the control signal generated in manual forwarding between the extensions of the TC system. The device for performing the method is integrated as a circuit arrangement in a TC system or designed as an adaptive device retrofitted on existing TC systems.

Verfahren zur erkennung einer internationalen roaming-beziehung

Abstract: Die Erfindung betrifft ein Verfahren zur Erkennung einer internationalen Roaming-Beziehung zwischen einem Heimat-Mobilfunknetz und einem Fremd-Mobilfunknetz, wobei der Signalisierungsverkehr zwischen dem Heimat-Mobilfunknetz und dem Fremd-Mobilfunknetz uberwacht und aufgezeichnet wird, und aus diesen Signalisierungsdaten die Identitat des Gastteilnehmers und das besuchte Fremd-Mobilfunknetz ermittelt wird. Anhand der ermittelten Identitat des Teilnehmers kann eine gezielte Benachrichtigung des Teilnehmers in Form einer Informationsnachricht oder einer Begrusungsnachricht erfolgen, die es dem Gastteilnehmer ermoglicht, sich besser im Fremd-Mobilfunknetz zu orientieren.

Method for verifying safety properties of java byte code programs

Abstract: In a method for verifying the safety properties of Java byte code programs, the functioning of the byte code program to be verified is modeled on a finite state transition system M, and the state space of the Java Virtual Machine (JVM) on a finite set of states in M. Once entered into a model checker, the data of finite state transition system M are compared to the data entered in the model checker as conditional set S to determine properties characterizing an acceptable byte code program. The byte code program to be checked is released for further processing only when the state transition system M fulfills all conditions of conditional set S.

Data coverage method for mobile vehicle, involves running user oriented standard program automatically, if remote control signals for program sequence are not received

Abstract: Program sequence on output media of vehicle, is controlled based on the remote control signals received in vehicle information system via digital audio broadcast. If remote control signals are not received, user oriented standard program is automatically run on the screen of vehicle information system. Off-line preproduced program contribution which are obviously identifiable are stored in portable storage media of vehicle information system in each vehicle. The remote control signals for program sequence is transmitted along with current passenger information and updating signals of preproduced information contribution, to vehicle information system via digital audio broadcast.