Tesis sobre el tema "Intensity Modulated -Direct Detection"
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Barrami, Fatima. "Low-complexity direct-detection optical OFDM systems for high data rate communications". Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAT057/document.
Texto completoA possible approach to maximize the data rate per wavelength, is to employ the high spectral efficiency discrete multitone (DMT) modulation. The work presented in this thesis mainly focuses on optimizing the power consumption and cost of DMT, that are the major obstacles to its market development. Within this context, we have first developed novel techniques permitting to discard the use of Hermitian symmetry in DMT modulations, thus significantly reducing the power consumption and the system cost. We have next proposed an asymmetric linear companding algorithm permitting to reduce the optical power of conventional DCO-OFDM modulation with a moderate complexity. A new VCSEL behavioural model based on the use of the VCSEL quasi-static characteristic was also developed to accurately evaluate the VCSEL impact on DMT modulations. Finally, we have built an experimental system to experimentally validate our proposed techniques. Several simulations and measurement results are then provided
Roth, Jeffrey Matthew. "Frequency modulated analog fiber optic links using direct detection". Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/43564.
Texto completoIncludes bibliographical references (p. 85-88).
by Jeffrey Matthew Roth.
M.Eng.
Erhart, Kevin. "A DIRECT COMPENSATOR PROFILE OPTIMIZATION APPROACH FOR INTENSITY MODULATED RADIATION TREATMENT PLANNING". Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2332.
Texto completoPh.D.
Department of Mechanical, Materials and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering PhD
Milette, Marie-Pierre. "Direct optimization of 3D dose distributions using collimator rotation". Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/274.
Texto completoZhang, Tianfang. "Direct optimization of dose-volume histogram metrics in intensity modulated radiation therapy treatment planning". Thesis, KTH, Skolan för teknikvetenskap (SCI), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231548.
Texto completoVid optimering av behandlingsplaner i intensitetsmodulerad strålterapi används dosvolym- histogram-funktioner (DVH-funktioner) ofta som målfunktioner för att minimera avståndet till dos-volymkriterier. Varken DVH-funktioner eller dos-volymkriterier är emellertid idealiska för gradientbaserad optimering då de förstnämnda inte är kontinuerligt deriverbara och de sistnämnda är diskontinuerliga funktioner av dos, samtidigt som båda också är ickekonvexa. Speciellt fungerar DVH-funktioner ofta dåligt i bivillkor då de är identiskt noll i tillåtna områden och har försvinnande gradienter på randen till tillåtenhet. I detta arbete presenteras ett generellt matematiskt ramverk som möjliggör direkt optimering på samtliga DVH-baserade mått. Genom att betrakta voxeldoser som stickprovsutfall från en stokastisk hjälpvariabel och använda ickeparametrisk densitetsskattning för att få explicita formler, kan måtten volume-at-dose och dose-at-volume formuleras som oändligt deriverbara funktioner av dos. Detta utökas till DVH-funktioner och så kallade volymbaserade DVH-funktioner, såväl som till mindos- och maxdosfunktioner och medelsvansdos-funktioner. Explicita uttryck för evaluering av funktionsvärden och tillhörande gradienter presenteras. Det föreslagna ramverket har fördelarna av att bero på endast en mjukhetsparameter, av att approximationsfelen till konventionella motsvarigheter är försumbara i praktiska sammanhang, och av en allmän konsistens mellan härledda funktioner. Numeriska tester genomförda i illustrativt syfte visar att slät dose-at-volume fungerar bättre än kvadratiska straff i bivillkor och att släta DVH-funktioner i vissa fall har betydlig fördel över konventionella sådana. Resultaten av detta arbete har med framgång applicerats på lexikografisk optimering inom fluensoptimering.
Bergman, Alanah Mary. "Monte Carlo simulation of x-ray dose distributions for direct aperture optimization of intensity modulated treatment fields". Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/30720.
Texto completoScience, Faculty of
Physics and Astronomy, Department of
Graduate
Al-Olofi, Mohammed [Verfasser]. "Transmission of Ultra-Wideband Radio System over Optical Wireless Links using Intensity Modulation Direct Detection / Mohammed Al-Olofi". München : Verlag Dr. Hut, 2016. http://d-nb.info/1113335602/34.
Texto completoMmbaga, Paul Fahamuel. "Study, analysis and application of optical OFDM, Single Carrier (SC) and MIMO in Intensity Modulation Direct Detection (IM/DD)". Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/15952.
Texto completoPerlot, Nicolas [Verfasser]. "Characterization of Signal Fluctuations in Optical Communications with Intensity Modulation and Direct Detection through the Turbulent Atmospheric Channel / Nicolas Perlot". Aachen : Shaker, 2006. http://d-nb.info/1186586001/34.
Texto completoGuillory, Joffray y Joffray Guillory. "Radio over Fiber (RoF) for the future home area networks". Phd thesis, Université Paris-Est, 2012. http://tel.archives-ouvertes.fr/tel-00786479.
Texto completoFerreira, Rafael Jales Lima. "Estudo de sistemas com multiportadoras ópticas ortogonais e coerentes". Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/18/18155/tde-29042013-113736/.
Texto completoThis manuscript presents a study on the multicarrier modulation technique OFDM (Orthogonal frequency division multiplexing) applied to optical systems. The OFDM technique provides a better use of bandwidth and, compared with FDM (Frequency Division Multiplexing), provides a nearly 50% reduction of the occupied bandwidth. This feature makes the OFDM technique an ideal candidate for reconfigurable optical networks because it allows better spectral efficiency to the signals with remote traffic reconfiguration. The study focuses, mainly, on the theoretical investigation of OFDM applied to the transmission of the so-called optical superchannels, modulated at very high bit rates (above Terabits/s). Two scenarios are discussed: in the first, the multicarrier signal, modulated in a hybrid format (QAM - quadrature amplitude modulation), is generated in the electrical domain before modulating the optical carrier, and in the second the multicarrier beam is generated in the optical domain and subsequently each subcarrier is digitally modulated. In this second approach, three superchannel generation techniques are studied and evaluated for being compared. This work will also compare the direct and coherent detection techniques applied to OFDM systems. The results for the optical multicarrier generation study, obtained by numerical simulation (platform Optisystem v. 9.0), are validated by experimental results obtained at the Laboratory of Optical Communication CPqD Foundation.
Hamze, Mohamad. "Study of different SOA structures impact on the transmission of IMDD OOFDM signals". Thesis, Brest, 2015. http://www.theses.fr/2015BRES0026/document.
Texto completoThe thesis work deals with study of different SOA structures impact on the transmission of intensity modulation and direct detection OFDM signals in the context of the next generation access networks. In the first part of the work, we have experimentally validated a comprehensive wideband RSOA field model. It was the nused as part of a co-simulation platform for IMDD-OOFDM and OOFDM wavelength conversion transmission systems. Thanks to this co-simulation platform that presents good agreement with the measurement, and our experimental setup, we analyze the transmission performance in terms of optical input power, fiber length, ASEnoise, electrical bandwidth and RSOA nonlinearities. We showed by simulation that an AMOOFDM signal transmission over a 100 nm wavelength range with a minimum transmission capacity of 8.9 Gb/s for fiber lengths up to 100 km can be reached. Finally, we experimentally demonstrated, for the first time to the best of our knowledge, the feasibility of performing wave length conversion over 70 nm of OOFDM-16QAM optical signals using the XGM effect in an RSOA. In the second part of this work we develop a simplified quantum dot –SOA and two electrode SOAintensity modulator models and study their effect on a numerical OFDM IMDD transmission system, we also study a two cascaded SOA in a counter propagating configuration as an intensity modulator. We find that for the three configurations we can achieve a high transmission capacity of around 30 Gb/s for transmission distances up to 60 Km, we also find that the QD-SOA will have the best performance in terms of transmission capacity for distances up to 140 Km in comparison with the two other SOA configurations
Guillory, Joffray. "Radio over Fiber (RoF) for the future home area networks". Thesis, Paris Est, 2012. http://www.theses.fr/2012PEST1083/document.
Texto completoThe evolution of the Home Area Network (HAN) is lead by the proliferation of connected devices inside the home and the deployment of high broadband access network which now allows the delivery of services that can exceed 1Gbit/s. To ensure efficient in-house exchanges, the HAN has to move rapidly toward multi-Gigabit/s connections, in particular the wireless connectivity generally preferred by the customers. Current wireless systems have limited capacities, but new radio standards delivering data-rates up to 7Gbit/s are emerging. Nevertheless, as they address the unlicensed millimeter-wave band, from 57 to 66 GHz, their radio coverage is limited to a single room. Indeed, at such frequencies, the free-space losses are high and the waves do not cross the walls. This thesis proposes to solve this problem by means of the Radio over Fiber (RoF) technology. This consists in capturing the 60GHz radio signals emitted in one room, converting them into optical signals for transmission through optical fibers, and reemitting them in another room. Thus, several RoF transducers will be installed in the home and interconnected by a suitable optical infrastructure to create systems acting at the same time as repeaters and as distribution systems. From the viewpoint of the HAN market, such systems will be competitive only if they are low cost. As a consequence, this work focuses on direct modulation with direct detection (IM-DD) at Intermediate Frequency (IF). In other words, the 60GHz signal is down-converted at a lower frequency around 5GHz before the laser modulation and up-converted to 60GHz after the photodetection. Concerning the optical fiber, silica multimode fiber (MMF) is privileged as it allows the use of low cost and largely available optoelectronic devices working at 850nm.The thesis proposes different RoF architectures, from point-to-point interconnecting two rooms to multipoint-to-multipoint acting as logical buses. After an analog characterization of the optoelectronic components, the RoF link and the domestic cable, these architectures are designed, built and characterized step by step using OFDM modulation according to existing wireless 60GHz standards. Real-time transmissions between commercial devices have also been performed to validate these architectures. Moreover, advanced RoF infrastructures are proposed. First, the RoF systems can be easily improved if the access to their optical media is managed by the radio MAC layer. This approach is therefore studied showing its feasibility. Secondly, an optical system, seen by users as a premium product, has to support the legacy home services commonly used as well as the new ones that could emerge in the future. Thus, innovative multiservice and multiformat infrastructures conveying on a unique optical cable wired IP data, broadcast terrestrial or satellite television, the 60GHz wireless connectivity, and specific formats as HDMI signals are proposed and tested
Mestre, Adrover Miquel Angel. "Data center optical networks : short- and long-term solutions". Thesis, Evry, Institut national des télécommunications, 2016. http://www.theses.fr/2016TELE0022/document.
Texto completoData centers are becoming increasingly important and ubiquitous, ranging from large server farms dedicated to various tasks such as data processing, computing, data storage or the combination thereof, to small distributed server farms. The spread of cloud services is driving a relentless increase of traffic demand in datacenters, which is doubling every 12 to 15 months. Along this thesis we study the evolution of data center networks and present short- and long-term solutions for their physical intra-connection. Today, rapidly-growing traffic in data centers spotlights the urgent need for high-speed low-cost interfaces capable to cope with hungry-bandwidth demanding new applications. Thereby, in the short-term we propose novel high-datarate low-cost optical transceivers enabling up to 200 Gb/s transmission using intensity-modulation and direct-detection schemes. Several advanced pulse amplitude modulation schemes are explored while increasing speeds towards record symbol-rates, as high as 100 GBd. High-speed electrical signaling is enabled by an integrated selector-power digital-to- analog converter, capable of doubling input baud-rates while outputting advance multi-level pulse amplitude modulations. Notwithstanding, data centers’ global traffic will continue increasing incessantly. Current datacenters rely on high-radix all-electronic Ethernet switches to build an interconnecting network capable to pave with such vast amount of traffic. In such architecture, traffic growth directly relates to an increase of networking components, including switches with higher port-count, interfaces and cables. Unsustainable cost and energy consumption that can be expected in the future calls for a network reassessment. Therefore, we subsequently present a novel concept for intra-datacenter networks called burst optical slot switching (BOSS); in which servers are connected via BOSS nodes through wavelength- and time-division multiplexed fiber rings organized in a Torus topology. Along this thesis we investigate on the implementation of BOSS nodes; in particular, the switching fabric and the optical transceivers. The main element within the switching fabric is the slot blocker, which is capable of erasing any packet of any wavelength in a nanosecond time-scale. On the one hand, we explore the use of semiconductor optical amplifiers as means of gating element to be used within the slot blocker and study their cascadability. On the other hand we develop a monolithically integrated slot blocker capable of handling up to sixteen wavelength channels with dual-polarization diversity. Then we present several transceiver architectures and study their performances. Transceivers’ signaling needs to fulfill two main requirements: packet-mode operation, i.e. being capable of recovering few microsecond –long bursts; and resiliency to tight filtering, which occurs when cascading many nodes (e.g. up to 100). First we build packet-mode Nyquist-pulse-shaped N-QAM transceivers, which adapt the modulation format as a function of the number of nodes to traverse. Later we propose the use of coherent-optical orthogonal frequency division multiplexing (CO-OFDM). With inherent packet structure and high spectral tailoring capabilities, we demonstrate that CO-OFDM-based transceivers offer higher capacity and enhanced reach than its Nyquist counterpart. Finally, we compare our BOSS solution to today’s Folded Clos topology, and show that our BOSS architecture requires x400 fewer transponders and cables than today’s electronic switching networks, which paves the way to highly scalable and sustainable datacenters
Chia-chen, Hsieh. "Single Carrier Modulation with Frequency Domain Equalization for Intensity Modulated-Direct Detection Channels with Intersymbol Interference". 2006. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2607200609383500.
Texto completoHsieh, Chia-chen y 謝佳辰. "Single Carrier Modulation with Frequency Domain Equalization for Intensity Modulated-Direct Detection Channels with Intersymbol Interference". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/02984940746478630027.
Texto completo國立臺灣大學
電信工程學研究所
94
In this thesis, we examine single carrier modulation with frequency domain equalization (SC-FDE) for optical communication systems using intensity modulation with direct detection (IM/DD) in the presence of additive white Gaussian noise. SC-FDE is a technique whose processing is quite similar to that of OFDM. Unlike OFDM, however, SC-FDE is compatible with IM/DD channels because it does not require the transmission of a strong dc. For an IM/DD channel, at high data rate regime, the effect of intersymbol interference (ISI) starts to dominate system performance. Inthis paper, we examine the use of SC-FDE and pulse position modulation (PPM) to combat ISI for IM/DD channels. Such a system enjoys the average power efficiency of PPM and the low complexity equalization of SC-FDE. We analyze the bit error performance of SC-FDE and compare it with a few known techniques.
Ahmed, Iftikhar. "Direct bit detection receiver noise performance analysis for 32-PSK and 64-PSK modulated signals". Thesis, 1987. http://hdl.handle.net/10945/22753.
Texto completoSimple two channel receivers for 32-PSK and 64-PSK modulated signals have been proposed which allow digital data (namely bits), to be recovered directly instead of the traditional approach of symbol detection followed by symbol to bit mappings. This allows for binary rather than M-ary receiver decisions, reduces the amount of signal processing operations and permits parallel recovery of the bits. The noise performance of these receivers quantified by the Bit Error Rate (BER) assuming an Additive White Gaussion Noise interference model is evaluated as a function of E^/N^, the signal to noise ratio, and transmitted phase angles of the signals. The performance results of the direct bit detection receivers (DBDR) when compared to that of conventional phase measurement receivers demonstrate that DBDR's are optimum in BER sense. The simplicity of the receiver implementations and the BER of the delivered data make DBDR's attractive for high speed, spectrally efficient digital communication systems.
Sekerefeli, Mehmet Sevki y Daniel C. Bukofzer. "Direct bit detection receiver performance analyses for 8-DPSK and 16-DPSK modulated signals operating with improper carrier phase synchronization". Thesis, 1987. http://hdl.handle.net/10945/22245.
Texto completoLai, Tsan Ning y 賴璨寗. "Application of Multi-code Interference cancellation Algorithm for an Intensity Modulation Direct Detection Multicarrier Code Division Multiple Access Passive Optical Network". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/6q224b.
Texto completo國立清華大學
通訊工程研究所
104
Orthogonal frequency division multiplexing (OFDM) passive optical network (PONs) implementing with double-side band intensity modulation and direct detection (IMDD) is considered as a cost-effective design. However, radio frequency (RF) power fading induced by chromatic dispersion causes non-uniform receiving performance among users. Generally speaking, user who suffered from the most serious fading cannot reach the specific forward error correction (FEC) threshold. To solve above dilemma, most of researchers adaptively design signal level in optical line terminal (OLT) depending on different transmission distance. However, such adaptive approach hugely enhances the system complexity and hardware costs. Therefore, we employ multicarrier code division multiple access (MC-CDMA) technique to equalize users’ received performance via spreading subcarriers’ data with orthogonal code. After frequency spreading, all users would suffer from the same RF power fading response and thus have the same performance. In this thesis, we simulatively and experimentally proof that the proposed MC-CDMA PON could achieve a universal transmitter design for users ranging from back-to-back to 100 km. Meanwhile, we apply minimum mean square error (MMSE) equalizer, combining with multi-code interference (MCI) cancellation digital signal process (DSP) to further enhanced system performance in a long reach PON. Our experimental results reveal that even under about 20 dB RF power fading, the proposed scheme can still provide 21.7 dB power budget and only about 2 dB sensitivity deviation is observed.
Safari, Majid. "Relay-Assisted Free-Space Optical Communications". Thesis, 2011. http://hdl.handle.net/10012/5752.
Texto completo