Institute of Electron Technology
Biblioteka Cyfrowa Instytutu Łączności / National Institute of Telecomunications: Digital LibraryNot a member yet
2189 research outputs found
Sort by
An Algorithm for Enumerating SRLG Diverse Path Pairs, Journal of Telecommunications and Information Technology, 2010, nr 3
Get PDFTelecommunication networks are intrinsically multi-layered, a single failure at a lower level usually corresponds to a multi-failure scenario at an upper layer. In this context, the concept of shared risk link group (SRLG) allows an upper layer to select, for a given active path (AP), a backup path (BP), which avoids every SRLG that may involve the selected AP, in the event of a failure. That is a SRLG diverse path set maybe defined as a set of paths, between an origin and a destination, such that no pair of paths can be simultaneously affected by any given failure (or risk) in a single failure scenario. Firstly we present the formulation of the SRLG diverse path pair calculation problem in a directed network. An algorithm for enumerating SRLG diverse paths, by non decreasing cost of their total (additive) cost will be presented, which is based on an algorithm proposed for generating minimal cost node disjoint path pairs. The SRLG diverse path pairs may be node or arc disjoint, with or without length constraints. Computational results will be presented to show the efficiency of the proposed algorithm for obtaining node or arc disjoint SRLG diverse path pairs in undirected networks
Performance Comparison of Protection Strategies in WDM Mesh Networks, Journal of Telecommunications and Information Technology, 2010, nr 1
Get PDFRecent development in optical networking employing wavelength division multiplexing (WDM) fulfills the high bandwidth demand applications. Failure of such networks, leads to enormous data and revenue loss. Protection is one of the key techniques, which is used in designing survivable WDM networks. In this paper we compare dedicated and shared protection strategies employed inWDMmesh networks to protect optical networks failure, particularly fiber failure. Dijkstra’s shortest path algorithm is considered for carrying out simulations. The paper compares the performance of protection schemes, such as, dedicated path protection (DPP), shared path protection (SPP) and shared link protection (SLP) schemes. Capacity utilization, switching time and blocking probability are the parameters considered to measure the performance of the protection schemes. Simulation results show that, SPP is more efficient in terms of capacity utilization over DPP and SLP schemes, whereas, SLP offered better switching time than both DPP and SPP schemes. The average call drop rate is minimum for shared path protection scheme and maximum for shared link protection scheme
Channel Identification Using Chaos for an Uplink/Downlink Multicarrier Code Division Multiple Access System, Journal of Telecommunications and Information Technology, 2010, nr 1
Get PDFA scheme of chaotic spreading sequence for multicarrier code division multiple access system (MC-CDMA) is proposed to estimate the transmission channel. This system spreads spectrum and identifies the channel, simultaneously. The proposed scheme uses a chaotic sequence generated by a logistic map as a training signal and estimate channel parameters according to dynamics of the chaotic sequence. Encoding data by chaotic sequences is first built and then the orthogonal codes are used to spread the encrypted data for multiusers scheme. At the reception, first the channel parameters are identified using a training chaotic sequence in order to equalize the received data, and then the encrypted information is decoded for the desired user. The studies reveal that the proposed system (chaos plus orthogonal codes) significantly outperforms the Walsh-Hadamard code spreading in MC-CDMA system. The performance of the system is considered in the multiuser case by means of simulation. The simulation result shows that the proposed chaotic code spreading approach for channel identification achieves significant improvement in the channel identification, comparing to using others training sequence or the least square method
Internet Przyszłości – nowa generacja sieci telekomunikacyjnych. Telekomunikacja i Techniki Informacyjne, 2009, nr 3-4
Get PDFObecna sieć internet opiera się na stosie protokołów TCP/IP oraz dwóch głównych założeniach: na oferowaniu jednej klasy usług (tj. usługi best effort) oraz przewymiarowaniu sieci. Te założenia projektowe w istotny sposób ograniczają obecnie rozwój sieci internet, uniemożliwiając oferowanie usług wymagających przekazu informacjiw czasie rzeczywistym. W artykule przedstawiono wyniki dotychczasowych prac ukierunkowanych na wprowadzenie jakości przekazu pakietów w sieci internet oraz przyjęte na dzień dzisiejszy główne założenia budowy sieci, nazwanej Internet Przyszłości
Features of Formation of Radar-Tracking and Optical Images in a Mobile Test Stand of Radio-Vision Systems of a Car, Journal of Telecommunications and Information Technology, 2009, nr 1
Get PDFIn the report the features of formation of radar images (RI) and optical images (OI) in the mobile test stand of radiovision systems (RVS) of a car are presented. The radiovision system of a car (CRVS) of the millimeter-wavelength with frequency modulation is considered. Features of formation and processing of the radar-tracking image in CRVS are discussed, in particular: the sizes of the image, system of coordinates, primary and secondary processing of RI, requirements for speeds of transfer of figures in real time of processing, for subsystem of display of RI and synchronization. The structure of the mobile test stand of CRVS is described. This stand consists of: CRVS, a video camera, the module of formation, recording and display of RI and of optical images, the module of control of a stand, the power supply unit. Features of formation and display OI are considered, in particular: the coordination of scale and shortening of images, creation of time synchronization at display and records of OI, and questions of synchronous fusion of RI and OI also
The Design of 4××4 4 Multimode Interference Coupler Based Microring Resonators on an SOI Platform, Journal of Telecommunications and Information Technology, 2009, nr 2
Get PDFThis paper would like to propose a novel microring resonator based on 4 ×4 multimode interference (MMI) couplers. The device acts as two separate microring resonators just in one structure. The transfer matrix method and the three dimensional beam propagation method (3D-BPM) are used to verify the working principle of the device. The device is then designed on silicon on insulator (SOI) technology. This device may be a very promising building block for optical switches, filters, add-drop multiplexers, delay lines and modulators
Rare Earth Silicate Formation: A Route Towards High-k for the 22 nm Node and Beyond, Journal of Telecommunications and Information Technology, 2009, nr 4
Get PDFOver the last decade there has been a significant amount of research dedicated to finding a suitable high-k/metal gate stack to replace conventional SiON/poly-Si electrodes. Materials innovations and dedicated engineering work has enabled the transition from research lab to 300 mm production a reality, thereby making high-k/metal gate technology a pathway for continued transistor scaling. In this paper, we will present current status and trends in rare earthbased materials innovations; in particular Gd-based, for the high-k/metal gate technology in the 22 nm node. Key issues and challenges for the 22 nm node and beyond are also highlighted