ItemMeasurement and simulation of non-linear microwave amplifiers operating in digital transmission systems(2001-03-12) Csörnyei, Márk; Klein, Balázs; Berceli, Tibor ItemOptikai-fotonikai technikán alapuló nyalábalakítás a vezeték nélküli hírközlésben(Napkút Kiadó, 2023) Frigyes, István ItemFiber-delay lines for intensity noise suppression in optical links(2005-06) Csörnyei, Márk; Berceli, TiborIn case of short haul optical links, optical local area networks or optical-mobile networks the most important noise source is the relative intensity noise (RIN) of the laser diodes. This paper will report on a new all-optical technique of intensity noise suppression for semiconductor lasers. The new scheme we have used is based on an Unbalanced Mach-Zehnder Interferometer (UMZI), which is able to cancel the intensity noise enhancement in the microwave domain and thus improve the link signal-to-noise ratio. Extending the UMZI to fiber-delay line filter the noise reduction capability can be further increased. Additionally the condition of stable, incoherent operation is detailed. ItemArchitectural elements of a framework for building model based software assistants(Budapest University of Technology and Economics, 2000) Tilly Károly ItemSEIS: a program control flow graph encoding algorithm for flow checking(Technical University of Budapest, 1994) Majzik István ItemInternational journal no. 5. joint to International symposium on theoretical electrotechnics(Technical University of Budapest, 1994) Iványi Amália ItemContest: an automatic test pattern generation system based on constraints(Technical University of Budapest, 1994) Tilly Károly ItemA comparative study of automatic test pattern generation and constraint satisfaction methods(Technical University of Budapest, 1994) Tilly Károly ItemThe application of intelligent diagnostic centers in the implementation of distributed fault-tolerant systems(Technical University of Budapest, 1994) Tilly Károly; T. Dobrowiecki; I. Majzik; A. Somogyi; A. Várkonyi-Kóczy; I. Kiss; Z. Dankó; Cs. Tóth; B. Vadász; T Zsemlye ItemSpectral correlation measurement: extended ad revised text of the lecture presented at the 4th International biennial seminar on intelligent measuring system design, Budapest - Göd, July 3-5. 1992 …(Technical University of Budapest, 1993) Reiner Thomä ItemCongestion control and queueing models in ATM networks(Technical University of Budapest, 1993) Molnár Sándor ItemNew feedback structure for monolithic integrated instrumentation amplifiers(Technical University of Budapest, 1993) Zoltai József ItemOptikai-mikrohullámú szűrés fénytávközlő rendszerek intenzitászajának csökkentésére(2005) Csörnyei, Márk; Berceli, TiborElsôsorban rövidtávú üvegszálas összeköttetések, így helyi, városi hálózatok, valamint optikai-mobil rendszerek esetén alézerdiódák relatív intenzitászaja (RIN) az átvitel legjelentôsebb zajforrása. A következôkben az intenzitászaj csökkentésérekidolgozott új, kizárólag passzív optikai eszközöket használó zajcsökkentô eljárást mutatunk be. Az új elgondolás szerint ki-egyenlítetlen Mach-Zehnder interferométert (Unbalanced Mach-Zehnder Interferometer, UMZI) használva, illetve azt optikaitranszverzális szûrôvé alakítva, lehetôvé válik a lézerdiódák esetén a mikrohullámú tartományban jelentkezô RIN jelentôscsillapítása és ezáltal az optikai vevôben mérhetô jel-zaj viszony javítása. A zajcsökkentô struktúra bemutatásán túlmenôen,a stabil mûködéshez szükséges inkoherens megvalósítás lehetôségeit is tárgyaljuk. ItemMikrohullámú reflexiómérés hibájának csökkentése minimális érzékenységű kalibráció alkalmazásával(1993-08-09) Ladvánszky, János; Hilt, Attila; Csonka, IstvánExplicit kifejezést adunk a hibakorrekció utáni reflexiós tényezőnek a kalibráló elemek reflexiós tényezőire vontakozó érzékenységeire és megmutatjuk összefüggésük invarianciáját. Az érzékenységek összegének állandósága mellett az érzékenységek abszolut értékének összege globális minimumot ér el, ha a mért reflexiós tényező egybeesik a kalibráló elemek reflexiós tényezői által a komplex síkon kifeszített háromszög magasságpontjával, vagy valamelyik kalibráló elem reflexiós tényezőjével. A bemutatott pldában a pontosságot ezzel a módszerrel 2,5-szeresére növeltük. ItemAvailability-Aware E-band Wireless Extension of Fiber-Access(2022-04-29) Hilt, Attila; Járó, Gábor; Varga, JózsefThe paper discusses availability of Gigabit/s (Gbps) fiber-optical access that are extended with E-band millimeter-wave (mmW) radio. Calculation method is shown for fixed fiber-wireless system, in which ‘fiber-like’ SLA (Service Level Agreement) has to be achieved. As shown, in ITU rainzone “K” Gbps throughputs can be achieved with mmW radios. Naturally, shorter radio links provide higher fade margins and better availability. However, as it is shown with a simple example, better system level availability may be achieved by connecting the radio to a FTTRN (Fiber to the Radio Node) where the fiber sections are protected or part of a loop. In practice, satisfying the availability target may require selecting a longer wireless link and not the shortest hop in an urban network environment. ItemRadio-Frequency Interference: An Overview for Access Network Planning(2000-11-20) Hilt, Attila ItemNew optomixer surpassing photodetection at microwaves(1997-09-03) Járó, Gábor; Berceli, Tibor; Hilt, Attila; Zólomy, AttilaThe properties of a new optomixing method are investigated and compared to the performance of the photodetection. This new method offers significantly higher output signal level compared to the direct photodetection. ItemEight-Octave Bandwidth Optical Receiver Using Distributed Amplification(1997-09-03) Zólomy, Attila; Berceli, Tibor; Hilt, Attila; Járó, Gábor; Aitchison, Colin; Baranyi, András; Ladvánszky, János; Liang, J.Y.A new approach us presented utilizing low-noise distributed amplification based on a hybrid integration technology, This way eight-octave bandwidth has been achieved with a responsivity characteristics flat from 40 MHz up to 10 GHz. ItemNew Carrier Generation Approach for Fiber-Radio Systems to Overcome Chromatic Dispersion Problems(1998-06-07) Hilt, Attila; Vilcot, Anne; Berceli, Tibor; Marozsák, Tamás; Cabon, BéatriceA new approach for the generation of millimeter-wave (MMW) carriers in fiber-radio systems is presented. A subharmonic of the carrier is transmitted to the radio nodes over the fiberoptic network. At each base station the MMW carriers are generated by a phase locked oscillator (PLO) using harmonic mixing technique. Due to the subharmonic reference transmission, chromatic dispersion in the optical path is avoided. Further advantage is the inherent possibility of channel selection to avoid radio interference between adjacent transmitters. ItemImproved Optical-Microwave Mixing Process Utilizing High-Speed Photo-diodes(1996-09-09) Berceli, Tibor; Cabon, Béatrice; Hilt, Attila; Járó, GáborMixing of lightwaves and microwaves offers new perspectives for the reception of subcarrier multiplexed (SCM) optical signals, Berceli (1). The received signal can be selected more easily and thus the receiver is significantly simplified. The new mixing method applying high-speed photodiodes presented in the paper is very promising because of its rather flat mixing response up to very high frequencies. Applying the new mixing process much higher subcarrier frequencies can be received thus enhancing the SCM optical transmission capacity of such a system. ItemThroughput Estimation of K-zone Gbps Radio Links Operating in the E-band(2022-04) Hilt, AttilaNowadays covid virus changes our work, learning and life-style. Broadband telecommunication channels are required for remote work, e-learning and video conferencing. Optical-fiber access offers the required wide bandwidths and low latencies. However, due to technical and business reasons optical-fiber cannot yet reach all homes, all offices or industrial plants. Mobile network sites often meet similar problems in urban environment. Since the introduction of mobile data (e.g., High-Speed Packet Access in 3G networks) and with the actual 4G expansion and 5G deployments, more and more cell-sites are connected to the fiber backhaul. But not all radio nodes can benefit the enormous bandwidth provided by optical-fiber access. The missing section between the fiber end-point and the site is often only few hundred meters, one or two kilometers. More and more millimeter-wave radios are deployed to reach the fiber access point. As radio links suffer from rain, atmospheric attenuation and interference, careful design is required. This paper focuses on digital radio links operating in the E-band (71-86 GHz) in Central Europe, where rainfall rates reach 42 mm/h (e.g., Slovenia and Hungary). In the paper a step-by-step planning method is shown to estimate the yearly radio throughput. It is shown that E-band radio links can reach Gigabit/s (Gbps) speed and availability figures comparable to optical-fiber connections. ItemGbit Radios for the Mobile Anyhaul(2022-02-04) Hilt, AttilaTraditionally, the microwave and millimeter-wave (μ/mmW) links have been limited by thermal noise. Long microwave hops had to connect distant sites of several kilometers. The antennas were mounted on high altitude towers. Unwanted interference was eliminated with proper link design and frequency re-use plans. The link design focused on Free Space Loss, rain and atmospheric attenuation. Fading events (e.g., attenuation due to rain or multipath) can significantly reduce the received signal level and degrade the link performance. In worst case, the microwave connection is cut resulting in outage. In the last two decades we observed a rapid breakthrough in direct fiber-optical access. The very long microwave backbone links have been systematically replaced by fiber-optics wherever it was possible by terrain conditions. Consequently, the majority of μ/mmW links became shorter and shorter. In urban environments, the wireless hops are typically shorter than five-six kilometers. On the other hand, there is a huge demand for a flexible LTE, 5G and 6G front- and backhaul (commonly called anyhaul). In mobile systems the μ/mmW anyhaul became extremely dense. 5G and 6G mandate challenging user bit rate and latency requirements.To avoid radio interference and support high link throughputs, higher and higher carrier frequencies are introduced. State-of-theart radios offer excellent possibilities in the millimetric (E, V and W) bands. In the paper the long road to nowadays Gigabit radios is presented. Starting from the very early microwave experiments, the evolution of mobile networks and anyhaul is shown. Finally, some design examples are presented for the recent use of the E-band. ItemRemote Upconversion in Microwave Fiber-Optic Links Employing an Unbalanced Mach-Zehnder Interferometer(1999-07-23) Gislaine Maury, Márk; Hilt, Attila; Cabon, Beatrice; GIROD, vincent; Degoud, LWe present a new technique for remote upconversion by inserting a passive all-optical device in the microwave (MW) fiber-optic link. Using a semiconductor laser directly modulated by two MW signals and an unbalanced Mach-Zehnder interferometer (UMZ) to convert optical frequency modulation (FM) into intensity modulation (IM), mixing is achieved after photodetection. Experiments with a UMZ integrated on glass-substrate have demonstrated the feasibility of this optical method for MW mixing with a low cost device of easy fabrication. Temperature control of the device allows optimized mixing performance and stable response. This method permits to overcome the effect of chromatic dispersion in standard singlemode fiber systems operating in the 1.55 μm wavelength window. Due to the presence of high-frequency fundamental components in the optical field, the received power is considerably degraded during transmission and direct detection in conventional systems, using either direct or external modulation in the MW band. With the proposed technique, lower frequency components of the field can be transmitted. The insertion of the simple UMZ generates high frequency only at detection side, therefore the available fiber length is extended. As it is shown by simulation results, this method can be used for the upconversion of MW subcarriers carrying digital signals. ItemReduction of Measurement Error in Microwave Reflectometers by Minimum Sensitivity Calibration(1993-07-08) Ladvánszky, János; Hilt, Attila; Csonka, IstvánExplicit formulas for the sensitivities of the error corrected reflection coefficient (RC) with respect to the RCs of the calibrating elements, and the invariance of their sum are presented. Under the condition that the sum of the sensitivities is constant, the sum of the absolute values of the sensitivities achieves a global minimum if the measured RC coincides with the altitude centre of the triangle formed by the RCs of the calibrating elements, or with one of the RCs of the calibrating elements. In the examples, 8 dB error reduction was found. ItemMicrowave Hop-Length and Availability Targets for the 5G Mobile Backhaul(2019-07-03) Hilt, AttilaDeployment of new radio access technology offers the possibility to optimize the existing mobile backhaul. Both the new technology (5G, LTE-A) and the legacy systems (LTE, HSPA, 3G, 2G) utilize the transmission and transport capacities of the backhaul extensively. The recent introduction of 5G requires again increased capacities. Consequently, more and more cell-site locations will receive fiber-optical backbone. Depending on the topology, the existing microwave and millimeter-wave links will “turn” towards aggregation points having fiber access. The increased density of cellsites reduces the hop-lengths, meanwhile adaptive modulation also provides the possibility of capacity increase. This paper reviews the availability and fade margin targets of the new links, that shall be carefully kept by proper planning and monitoring. ItemReliability and Availability Modelling of Telecommunication Servers on Cloud(2015-07-09) Hilt, Attila; Bakos, István; Járó, GáborReliability and availability considerations are discussed in this paper with special focus on ‘cloud based’ Mobile Switching and Application Servers (MSS and AS). Before the extensive deployment of cloud based telecom networks an essential question shall be answered: Will cloud technology ensure the ‘carrier grade’ requirements that are well established and proven on ‘legacy telecommunications’ hardware? This paper shows the possible redundancy principles and a simulation method to predict availability for ‘cloudified’ mobile communication network elements. As a calculation example, Nokia AS on ‘telco-cloud’ is presented, that combines several redundancy principles such as full protection (2N), load sharing and standby. ItemMicrowave Harmonic Generation in Fiber-Optical Links(2000-05-22) Hilt, AttilaOptical transmission of microwave (MW) and millimeter-wave (MMW) signals have become an intensive research area in the last decade. There is a growing interest in optical processing of MW signals [1, 2], phased array applications  and wireless distribution of broadband data in fiber-fed MMW subscriber access systems [4-9]. This paper extends the existing models of MW/MMW optical links that are based on optical intensity [10, 11]. The model is suitable for estimating harmonic levels of the MW modulation signal generated in the optical path. Considering a MW fiber-optic link both the optical transmitter and the receiver are responsible for harmonic generation. Furthermore, the optical fiber itself inserted between the transmitter and receiver induces harmonics due to dispersion. Exact modelling of harmonic generation requires a calculation based on the optical field instead of on a purely intensity basis [12-14]. ItemFixed MW Access Network Design Using Interference Matrices(2003-09-10) Hilt, Attila; Pap, TamásDensity of microwave and millimeter-wave radio relay networks increased with unexpected speed in the last decade. For long time rain attenuation and thermal noise limitation were in the main focus of fixed radiolink design. Nowadays interference between the wireless links became the major limiting factor in network planning. ItemOptical Upconversion of 100 Mb/s BPSK Microwave Subcarrier Signals Using an Unbalanced Mach-Zehnder Interferometer(2000-09-11) Maury, Ghislaine; Cabon, Beatrice; Hilt, Attila; Le Bigot, J-FrancoisA new technique for remote upconversion of a 100 Mb/s BPSK microwave subcarrier signal is proposed and demonstrated. It is based on the insertion of an unbalanced Mach-Zehnder interferometer in a microwave fiber-optic link. ItemInvestigations in Microwave Optical Links - Accent on QAM(2000-09-11) Frigyes István, Ferenc; Hilt, Attila; Csernyin, SándorVarious-depth field descriptions and their use are summarized. Effects in optical links are being investigated being of particular importance if QAM microwave signals are transmitted. In this framework modulator-induced nonlinear distortion, IBPD (In Band Power Difference) and fiber nonlinear refraction effects are discussed. ItemAccess-independent Cloud-based Real-Time Translation Service for Voice Calls in Mobile Networks(2018-07-20) Tündik, Máté Ákos; Hilt, Attila; Nagy, Loránd; Bóta, Gergő; Luukkanen, KalleNokia offers a speech translation solution for mobile networkoperators: Operators can provide real-time machine translation of speech, as a useful extension to their currently available voice service. The concept offers a beneficial difference against Over-the-Top (OTT) service providers. The successfully implemented solution presented in this paper works with any device, that is capable of voice calls, even with simple mobile handsets (feature phones). In the service, the Operator’s MSS (Mobile Switching Center Server) and/or IMS (IP Multimedia Subsystem) core is involved. The core network is connected to the Microsoft Azure Data Center that provides the speech translation through a Nokia Translation Application Server, running in a Nokia Data Center. ItemAccess Transmission Network Upgrade in a Nationwide Mobile Network Modernization Project for EDGE Deployment(2008-10-02) Hilt, Attila; Petrás, Péter; Emsley, Dean; Rybarczyk, GrzegorzIn this paper details of a nationwide fixed access transmission network upgrade is presented with special focus on GSM network modernization for EDGE (Enhanced Data rates for GSM Evolution) deployment. ItemDynamic Characterization of Optical-Microwave Transducers(1995-05-16) Berceli, Tibor; Cabon, Beatrice; Hilt, Attila; Ho Quoc, Anh; Pic, Étienne; Tedjini, SmailOptical-microwave transducers based on FET devices are investigated to determine their dynamic characteristics. It is observed that the result of the well known frequency response method differs from that of a combined test method applying simultaneously a microwave signal and a modulated lightwave for driving the transducer. Based on these investigations a more precise circuit model is established for illuminated FET devices. The new circuit model describes the operation of optical-microwave transducers like mixers, phase detectors, amplifiers, injection locked oscillators, and modulators ItemRecent Trends in Reliable Access Networking for GSM Systems(2001-10-10) Hilt, Attila; Pál, BerzéthyAccess networks for base stations in GSM systems are mainly based on microwave, millimeter-wave (MW/MMW) and fiber-optical technologies. This paper presents the recent trends of MW/MMW radio relay access networking with enhanced focus on interference, on frequency related issues and on loop protection technique.