Showing papers by "Deutsche Telekom published in 1995"

Phase-shifted Bragg-grating filters with improved transmission characteristics

Abstract: Standard Bragg filters (dielectric waveguides with a grating overlay) show a stopband only in reflection. Filters with quarter-wave-shifted gratings have an extremely narrow transmission peak the center of the stopband but its shape (a sharp triangle with a broad bottom) is not suitable for system design. Using standard coupled-mode theory together with transfer-matrix formalism, we show that by introducing several phase-shift regions and properly choosing their locations and magnitudes the transmission spectrum can be tailored into a nearly rectangular shape. For InP-InGaAsP based Bragg-grating filters estimates are made of achievable channel spacings in wavelength-division multiplexing systems.

10-Gb/s standard fiber transmission using directly modulated 1.55-μm quantum-well DFB lasers

Abstract: 10-Gb/s long-haul transmission on standard single-mode fibers at 1.55 /spl mu/m with intensity modulated, low-chirp MQW DFB lasers is investigated. Successful transmission is achieved by operating the laser at increased bias. Thus, the laser chirp acts favorably on the propagation after an initial distance of 30 km in the fiber. A detailed system evaluation with an optical preamplified PIN-receiver, reveals a negligible dispersion power penalty for transmission distances between 35 and 70 km. The power penalty, mainly caused by a lower extinction ratio, must be accepted. >

Conversion of the delayed LMS algorithm into the LMS algorithm

Abstract: For some applications of adaptive finite impulse response (FIR) filtering, the adaptation algorithm can be implemented only with a delay in the coefficient update. It is well known that this has an adverse effect on the convergence behavior of the algorithm. It is shown in which way the delayed LMS (DLMS) algorithm can be transformed into the standard LMS algorithm at only slightly increased computational expense.

Laterally tapered InP-InGaAsP waveguides for low-loss chip-to-fiber butt coupling: a comparison of different configurations

Abstract: Low-loss chip to-fiber coupling can be achieved by on-chip spot-size transformers. Two simple versions using laterally tapered InP-InGaAsP waveguides at the 1.55 /spl mu/m wavelength have been fabricated: one consisting of two differently tapered layers, the other with only one taper. The influence of the taper shape and of fabrication tolerances on their performance is compared both experimentally and theoretically. The optimum insertion loss for a single transformer without antireflection coating, including Fresnel losses, amounts to 1.1 dB. >

Method of determining toll charges for vehicles using a traffic route

Abstract: In the proposed method of determining toll charges for vehicles using a traffic route, a radiolocation system is used to compare a vehicle's geographical location continuously with the geographical location of virtual collection points The virtual collection points are formed by data acquisition sectors extending over predetermined distances in the direction of each route

Method and system for determining toll charges for traffic routes and/or areas

Abstract: With the proposed method and system for determining toll charges for traffic routes and areas, toll charges are calculated with the aid of a device installed in the vehicle on the basis of positional and tariff data. The data are then transmitted via a data transmission system to a central point, with the possibility of verification of the appropriate charge.

Tailored DFB laser properties by individually chirped gratings using bent waveguides

Abstract: DFB lasers with continuously and arbitrarily chirped gratings of ultrahigh spatial precision are implemented by a method we proposed recently, using bent waveguides on homogeneous grating fields. Choosing individual bending functions we generate special chirping functions and obtain additional degrees of freedom to tailor and improve specific device performances. We present two applications for lasers showing several improved device properties and the effectiveness of our method. First, we implement continuously distributed phase-shifted lasers, revealing a considerably reduced photon pile-up, higher single-longitudinal mode stability, higher output power, lower linewidth, and higher yield than conventional abruptly phase-shifted lasers. Second, a novel tuning principle is applied in chirped multiple-section DFB lasers, showing 5.5-nm wavelength tuning, without any gaps, maintaining high side-mode suppression. >

Method of allotting and withdrawing reception authorisation for chargeable reception

Abstract: The method could use a three-branch tree with two branching levels, such that the keys for the branches K (2,i) are stored in a decoder Di or a chip card, i having the values from 1 to 9. The root possesses the system key SK = K (O,1), while the keys for the other nodes are given. The keys stored in the decoder serve for decoding the received cryptograms or control words. Each cryptogram can allow a decoder to receive programmes, for example along the branch from K(2,1), through K(1,1) to SK = (0,1), when the decoder is D1 and the key is K(2,1).

Generation and distribution procedure for personal identification numbers

Abstract: The personal identification number (pin) generation and distribution procedure involves the initial setting of a personalised security module, esp a chip card, to a standardised pin number, designated by O-PIN This does not allow access to any of the normal functions of the card The O-PIN can only be used to change the pin number to the initial pin number chosen by that user Once the OPIN has been used once to set the user's chosen pin number, it can not then be re-used The user can check whether the card has been previously used by attempting to enter the O-PIN

An optical infrastructure for future telecommunications networks

Abstract: For the transport of the increasing traffic volume caused by existing and new narrowband services and evolving broadband services, the enhancement of the existing public telecommunication transport network is necessary. For this purpose an optical network layer with cross-connect and add/drop functionalities will be added to the existing transport network. A comparative analysis of space, time, and optical frequency division multiplexing has shown that for the time being optical frequency multiplexing is best suited for the realization of that new network layer. This multiplexing scheme offers the greatest advantages such as very high bandwidth utilization in the fiber and simple and efficient cross-connecting of high bitrate streams. In the near future, technology will be mature enough for the realization of a demonstrator network based on optical frequency division multiplexing. The functionalities of the optical network are evaluated and the results clearly show that optical frequency conversion and regeneration should be provided by the optical network. The article also deals with the realization aspects (cross-connecting, supervision, and operation and maintenance) of an optical node. >

Continuously chirped DFB gratings by specially bent waveguides for tunable lasers

Abstract: We have implemented and studied a new type of tunable multiple-section semiconductor distributed feedback (DFB) laser using tailored chirped DFB gratings. Arbitrarily and continuously chirped DFB gratings are defined by bent waveguides on homogeneous grating fields with ultrahigh spatial precision. The mathematical bending functions are optimized in this case to provide enlarged wavelength tuning ranges. We present the results of model calculations, the technological device realization and experimental results of the DFB laser characterization e.g. a tuning range of 5.5 nm without wavelength gaps and high side mode suppression ratio. >

Process and apparatus for locating mobile stations

Abstract: Process and apparatus for locating mobile stations in a cellular mobile radio network. The apparatus may include a plurality of radio cells in which each radio cell is supplied by at least one base station, a plurality of transmitters in which each of the plurality of transmitters establish a locally defined underlay broadcast cell, the plurality of transmitters being located within at least one of the plurality of radio cells, a signal receiving and evaluating device associated with a respective mobile station that receives signals from the plurality of radio cells and the plurality of transmitters, information comparing units associated with the respective mobile station that compare information about one of the plurality of underlay broadcast cells received from a corresponding base station of the mobile radio network and information about the locally defined underlay broadcast cell received from one of the plurality of transmitters, a position determination device, and a device that forwards information about the locally defined underlay broadcast cell from the one transmitter to the position determination device when the compared information agree. The process may include emitting an underlay broadcast cell from the base stations of the mobile radio network, receiving, at the mobile stations, information about the underlay broadcast cell emitted from a corresponding base station of the mobile radio network, receiving, at the mobile stations, information about the locally defined underlay broadcast cell emitted from the transmitter, comparing the information received at the mobile stations from the corresponding base station and the transmitter, and determining a position of the mobile stations with the information received from the transmitter if the compared information agree.

Smart card for access to global mobile communication system - has integrated circuit chip using identification and authentication data to control access

Abstract: The smart card is provide for access to a global system for mobile communication ,GSM. The card has an embedded integrated circuit that has a micro controller and an EEPROM memory. The circuit has identification data and authentication data in coded form that is independent of the terminal used for reading. Removal of the card during the operation terminates the cycle.

Location of origin of measuring data for radio characteristics of cellular network

Abstract: The measured values from the interface (Abis1) are recorded with a protocol analyser (2) and stored in a memory device or a database (3), so that they can be selected by the software (4) and sorted in the measuring vector bank (5). From the operation and maintenance controller (OMC) (6) the neighbourhood list of the server base station can be determined and stored in a memory device or database (7). From the list can be obtained the location, the elevation and the land utilisation data (8, 9). From the field strength unit (10) can be deduced the prediction data (11) and the predicted reception strengths for the server and neighbouring stations (20,...), together with the vector data (12, 12). The steps in the calculation involve the determination of the transmit times for signals in the cellular network, the determination of the transmitter parameters for at least one stationary transmitting and receiving units, and the prediction of the transmitting parameter.

Measurement and analysis of wide band indoor propagation characteristics at 17 GHz and 60 GHz

Abstract: A versatile impulse response measurement system based on a vector network analyser has been developed for indoor propagation measurements. The combination of the network analyser equipment with a high-precision positioning system offers a number of possibilities for comprehensive data analysis. In addition to detailed fading- and delay spread statistics spatial variations of impulse responses as well as spatial Doppler spectra can be studied. Using a simple transformation the directions of arrivals of multipath contributions are derived from the Doppler spectra. In the paper results measured at 17 GHz and 60 GHz are presented for different indoor environments. Measurements in an empty room have been performed to provide a reference for the comparison of different modelling approaches. The propagation conditions at a corridor are investigated in addition.

Miniature low voltage beam systems producable by combined lithographies

Abstract: The project of a miniaturized vacuum microelectronic 100 GHz switch is described. It implies the development of a field emission electron gun as well as the investigation of miniaturized lenses and deflectors. Electrostatic elements are designed and developed for this application. Connector pads and wiring pattern are created by conventional electron beam lithography and a lift-off or etching process. Wire and other 3-dimensional structures are grown using electron beam induced deposition. This additive lithography allows to form electrodes and resistors of a preset conductivity. The scanning electron microscope features positioning the structures with nm precision. An unconventional lithography system is used that is capable of controlling the pixel dwell time within a shape with different time functions. With this special function 3-dimensional structures can be generated like free standing square shaped electrodes. The switch is built by computer controlled additive lithography avoiding assembly from parts. Lenses of micrometer dimensions were investigated with numerical electron optics programs computing the 3-dimensional potential and field distribution. From the extracted axial field distribution the electron optic characteristic parameters, like focal length, chromatic and spherical aberration, were calculated for various lens excitations. The analysis reveals that miniaturized optics for low energy electrons, as low as 30 eV, are diffraction limited. For a lens with 2 μm focal length, a chromatic aberration disc of 1 nm contributes to 12 nm diffraction disc. The spherical aberration blurs the probe by 0.02 nm, assuming an aperture of 0.01 rad. Employing hydrogen ions at 100 V, a probe diameter of 0.3 nm generated by chromatic aberration is possible. Miniaturized electron optical probe forming systems and imaging systems can be constructed with those lenses. Its application as lithography systems with massive parallel beams can be forseen.

Estimating cell transfer delay in ATM networks using in-service monitoring methods

Abstract: Cell transfer delay (CTD) is a performance parameter of the ATM layer. Monitoring CTD requires procedures for in-service measurement or estimation and for gaining statistics of the delay distribution. This paper discusses the definition and origin of CTD, and looks at basic measurement techniques based on operation and maintenance (OAM) performance monitoring functions. It presents a method for estimating CTD, which does not rely on the availability of synchronized clocks at the measurement points. This method is based on a least-square regression analysis which estimates the time and frequency offset of the remote clock.

Coded 64-CAP ADSL in an impulse-noise environment-simulation results

Abstract: This paper describes performance results of E1-ADSL (2.048 Mb/s asymmetrical digital subscriber line) transmission based on carrierless amplitude/phase modulation (CAP) in an impulse-noise environment. Various coding schemes for error protection are investigated. Code options are Reed Solomon code with interleaving, array code and trellis coding, or interleaved trellis coding. The simulation results are based on real measured impulses from an impulse-noise measurement campaign carried out by German Telekom. The inter-arrival times between impulses were either assumed to be constant (worst-case scenario) or were delivered from a distinctive stochastic generator with an inter-arrival time density according to a model also derived in the German campaign. It was found that the RS codes, even with a quite small error-correcting capability, achieved acceptable error performance. Array codes can also be a low-complexity alternative. Trellis coding alone, as expected, was not very effective against the impulse noise.

AlGaInAs/InP 1.5 µm MQW DFB laser diodes exceeding 20 GHz bandwidth

Abstract: Buried mushroom multiquantum well DFB laser diodes with compressively strained GaInAs quantum wells and asymmetric confinement layer design are fabricated with a combined MBE/MOCVD technology. Packaged devices exhibit high –3 dB IM bandwidths for very low bias levels and a record bandwidth for this material system of 21 GHz.

Ablation of Si and Ge Using UV Femtosecond Laser Pulses

Abstract: Laser ablation of silicon and germanium was carried out in moderate vacuum with l00fs to 400fs pulses at 248nm and intensities up to 3x1013 W/cm2. Evidence for non-thermal material removal was found. Imaged multishot ablation patterns display the intensity dependentself-structuring effect, forming well-known columnar structures. It is shown that continued irradiation of these structures eventually results in comparatively clean ablation. An increase of ablation rate with depth was observed. The reason is an intensity enhancement inside the pits by reflective focussing to a level where bond-breaking takes place. Furthermore, it was noticed that ablation contours can be significantly improved by electrically grounding the target.

System zur Sicherung eines Fahrzeugs gegen unberechtigte Benutzung

Abstract: Bei einem System zur Sicherung eines Fahrzeugs (4) gegen unberechtigte Benutzung ist vorgesehen, das im Fahrzeug (4) eine Uberwachungseinrichtung (5) mit einem Sende/Empfangsgerat (7) fur ein Mobilfunknetz mit mindestens einer fur den Betrieb des Fahrzeugs (4) erforderlichen Fahrzeugeinrichtung, insbesondere Zundung (11), Kraftstoffpumpe (13), Anlasser, derart verbunden ist, das die Funktion der Fahrzeugeinrichtung durch die Uberwachungseinrichtung (5) blockierbar ist, das die Uberwachungseinrichtung (5) von Zeit zu Zeit eine Meldung uber das Mobilfunknetz an eine Zentralstelle (3) sendet und das die Uberwachungseinrichtung (5) die Funktion der Fahrzengeinrichtung blockiert, wenn keine Ruckmeldung empfangen wird.

Design and application of a femtosecond optical parametric oscillator for time-resolved spectroscopy of semiconductor heterostructures

Abstract: Femtosecond pulses of a collinearly pumped Optical Parametric Oscillator (OPO) are applied for investigations of the carrier dynamics in ternary and quaternary semiconductor quantum wells. The design and the specifications of the OPO are given in detail. We show that no measurable jitter exists between the pump pulses and the output pulses of the OPO. Therefore, it is possible to use the OPO and its pump laser for two-color experiments with a time resolution limited by the pulse lengths. We present and discuss results of transient four-wave mixing experiments on (InGa) As/InP quantum wells, and find a new kind of polarization-dependent quantum beat phenomenon. In addition, non-degenerate experiments on quantum wells from the quaternary (InGaAl) As material system, using two pulses at different wavelengths (one from the OPO and one from the pump laser), are discussed as a novel experimental technique to study carrier trapping into quantum wells.

MBE grown strain-compensated AlGaInAs/AlGaInAs/InP MQW laser structures

Abstract: Strain-compensated MQW structures with AlInGaAs barriers and up to 15 AlInGaAs wells were grown by molecular beam epitaxy (MBE) and characterised by photoluminescence and X-ray diffraction. Our structures show very low threshold currents of 4 mA and high AM modulation bandwidths of 21 GHz.

Verfahren zur ermittlung von gebühren für die nutzung von verkehrswegen durch fahrzeuge

Abstract: Bei einem Verfahren zur Ermittlung von Gebuhren fur die Nutzung von Verkehrswegen durch Fahrzeuge wird die geographische Position eines Fahrzeugs laufend mit Hilfe von Funkortung ermittelt und mit geographischen Positionen von virtuellen Erhebungsstellen verglichen. Die virtuellen Erhebungsstellen werden dabei von Erfassungsabschnitten gebildet, die sich uber vorgegebene Langen in Richtung des jeweiligen Verkehrsweges erstrecken.

Method of packet-wise data transmission in a mobile radio network

Abstract: A process for transmitting data in packets in a radio system with mobile and base stations labels the packets with indentification or code numbers which are used to route the packets over data traffic channels characterized in the allocated control channels as those containing the data packets by means of the identification number.

leanEA: A Lean Evolving Algebra Compiler

Abstract: The Prolog program “term_expansion((define C as A with B), (C=>A:-B,!)). term-expansion((transition E if C then D), ((transition E):-C,!,B,A,(transition _))):-rearrange(D,B,A). rearrange((E,F),(C,D),(A,B)):-rearrange(E,C,B), rearrange(F,D,A). rearrange(F:=G, ([G]=>*[E], F=. [C¦D], D=>*B,A=. [C¦B]), asserta(A=>E)). [G¦H]=>*[E¦F]:-(G=>E; G=.[C¦D], D=>*B,A=.[C¦B],A=>E), !,H=>*F. []=>*[]. A=?B:- [A,B]=>*[D,C], D==C.” implements an efficient and flexible simulator for evolving algebra specifications.

Quadrature amplitude modulation transmission system

Abstract: The transmission system uses amplifier circuits with separate phase and amplitude control, the signals to be transmitted converted into digital signals with successive multi-stage symbols selected from a defined complex value symbol alphabet via the input signal. The real and imaginary components of the selected symbols are filtered for reducing their bandwidth and used for determining the phase and amplitude control of the amplifier circuits in the modulation end stage.

Verfahren und anordnung zur ermittlung von nutzungsgebühren für verkehrswege und/oder verkehrsflächen

Abstract: Bei einem Verfahren und einer Anordnung zur Ermittlung von Nutzungsgebuhren fur Verkehrswege und/oder Verkehrsflachen werden mit Hilfe einer in einem Fahrzeug befindlichen Einrichtung aufgrund von Positionsdaten und Tarifdaten Nutzungsgebuhren berechnet und uber ein Datenubertragungssystem an eine Zentralstelle ubertragen mit der Moglichkeit einer Uberprufung der ordnungsgemasen Zahlung .

Intelligent card for mobile radio network system

Abstract: The chip-card includes several subscriber identities provided on a semiconductor chip of the card. Each of which represents an adequate subscriber ratio. The chip-card is assigned only one PIN number and each subscriber is assigned an identifier in the form of a number. A respective subscriber identity is activated by inputting an identifier in connection with the PIN number.