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1
Content available Novel rogue optical network unit detection algorithm for gigabit passive optical networks
Horvath T., Munster P., Dubravec L., Filka M.
Optica Applicata
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2016
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Vol. 46, nr 3
421--433
EN
Passive optical networks are widely used as a promising solution for future access networks. Currently, the bandwidth is still increasing which means the current copper networks are not able to transfer new services such as 4K video, live streaming, etc. In other words, they reached their capacity limit. The passive optical networks rely on point-to-multipoint technology. That means each customer uses a share medium by time slots. Each time slot exactly specifies who and when is able to transfer data. In general, this control mechanism is implemented in the optical network unit by worst transmission convergence layer. On the other hand, there are cases when the optical network unit (it is called rogue optical network unit) does not follow instructions provided by the optical line termination, for example, if an attacker modifies a firmware of the end unit and/or when the control protocol is not loaded properly inside optical network unit. In worst case, the optical network unit transmits data in a continual mode (other optical network units cannot send data). Thestandard defines finding of the rogue optical network unit but it does not specify how the rogue optical network unit should be allocated because the frames of the rogue optical network unit do not contain the proper parameters. We realized a measurement in a real network with the rogue optical network unit and then we analyzed the captured data. A new algorithm for the rogue optical network unit allocation is presented. We do not consider any modification of the transmission convergence layer in gigabit passive optical networks.
2
Content available remote The most frequent shortcomings of Wi-Fi operators
Grenar M., Filka M.
Przegląd Elektrotechniczny
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2015
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R. 91, nr 6
129-133
EN
This paper is focused to the most frequent shortcomings of WiFi technology operators seen by monitoring of broadband data transmission in frequency bands 2.4 GHz up to 66 GHz. The used process of measuring an evaluation of measured data summarized by the devices used by Czech Telecommunication Office for inspection and supervision is performed next. The paper is concluded by real examples of various shortcomings and mistakes.
PL
W artykule analizowano najczęściej pojawiające się wady technologii WiFi występujące w paśmie 2.4 GHz - 66 GHz. Badano układy stosowane przez Czeski Urząd Telekomunikacji.
3
Content available Timing measurement and simulation of the activation process in gigabit passive optical networks
Horvath T., Munster P., Jurcik M, Koci L, Filka M.
Optica Applicata
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2015
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Vol. 45, nr 4
459--471
EN
The passive optical networks are widely used nowadays. Service providers have many customers in their distribution networks. The most important thing for communication between the end unit and the control unit is an establishment contact. Design and measurement of the activation process between optical network unit and optical line termination is presented. In general, the service providers have a big split ratio (up to 1:128) due to the connection eminent value of the customers per optical line termination port in chassis. We present the simulation of the connection process for 16, 32, 64, and 128 optical network units and the measurement for single optical network unit (the GPON Xpert is able to read a single connection process). We compare our results in simulation discussion.
4
Content available Distributed Fiber-Optic Sensor for Detection and Localization of Acoustic Vibrations
Sifta R., Munster P., Sysel P., Horvath T., Novotny V., Krajsa O., Filka M.
Metrology and Measurement Systems
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2015
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Vol. 22, nr 1
111--118
EN
A sensing system utilizing a standard optical fiber as a distributed sensor for the detection and localization of mechanical vibrations is presented. Vibrations can be caused by various external factors, like moving people, cars, trains, and other objects producing mechanical vibrations that are sensed by a fiber. In our laboratory we have designed a sensing system based on the Φ-OTDR (phase sensitive Optical Time Domain Reflectometry) using an extremely narrow laser and EDFAs.
5
Content available remote Simulation of bidirectional traffic in WDM-PON networks
Sifta R., Munster P., Krajsa O., Filka M.
Przegląd Elektrotechniczny
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2014
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R. 90, nr 1
95--100
EN
The paper is focused on the design and simulation of bidirectional WDM-PON networks using the OptSim v5.2 simulation software. First, this type of passive optical network is described. Then the possibilities of its simulation, especially simulation of bidirecti onal traffic, which is not commercially supported by this software, are also shown. Finally, an analysis of the transmission parameters is given.
PL
W artykule opisano projekt i symulację dwukierunkowej sieci typu WDM-PON przy wykorzystaniu oprogramowania OptSim. Na wastępie opisano sieć pasywną a następnie przedstawiono symulację ruchu dwukierunkowego. Przedstawiono parametry transmisji.
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