¡@¡@The ever-increasing requirement for more bandwidth to the office, home, and mobile devices is driving the deployment of high-speed optical communication systems. Differential quadrature phase-shift keying (DQPSK) is one of the most attractive and advanced modulation format in recent years, and this format increases the capacity and efficiency in optical fiber communication systems. ¡@¡@DQPSK is able to transmit two bits per symbol. That is to say that DQPSK has twice spectral efficiency compared to DPSK. In addition, DQPSK has excellent tolerance against chromatic dispersion (CD), polarization-mode dispersion (PMD), optical add-drop multiplexing (OADM) filtering, and optical noise. It makes DQPSK play an important role for next-generation optical transmission systems. ¡@¡@The wavelength-division multiplexing system (WDM) multiplexes multiple optical carriers in the single optical fiber by using the different wavelengths of laser to carry the signal. This master thesis focuses on the study of DQPSK performance in the long-haul transmission with the WDM system. ¡@¡@In the process of experiment, a special technique for DQPSK to be set up is required. When a delay demodulator is applied for the DQPSK signal, decoding is required to make the received serial data become the same as the transmitted serial sequence. As the electronic encoder or decoder is hard to realize, a program is prepared for the experiment to calculate the pre-decoded pattern sequence. Then, calculated patterns are imported to the error detector (ED) to measure the bit error rate (BER). Finally, different channels (wavelengths) of WDM transmission were observed.

The growing demand in the telecommunication systems makes the high speed transmission technology important. The Differential Quadrature Phase Shift Keying (DQPSK) is one of the most attractive and advanced modulation formats in recent years, Compared to the Differential Phase Shift Keying (DPSK), it can double the spectrum efficiency, because it can carry two bits in one symbol. In addition, the DQPSK has excellent tolerance against the chromatic dispersion (CD), the polarization mode dispersion (PMD), the optical filtering due to the optical add and drop multiplexer (OADM) and the optical noise. Compared to other coherent modulation formats, the DQPSK signal can be detected directly through a delay interferometer, and it does not need the local oscillator light, so it reduces the complexity of the system setup. We can say that the DQPSK plays an important role for the next generation system. Wavelength Division Multiplexing system (WDM) multiplexes multiple optical carriers in a single optical fiber by using different wavelength of lasers to carry the signal, therefore, increase the wavelength channels makes the system capacity increase. This master thesis focuses on the performance of the WDM system with the DQPSK modulation format in the long haul transmission system. Experiments to demonstrate the QPSK transmission are discussed. To realize the differential modulation, encoders or decoders are necessary. However, electrical encoder or decoder is hard to realize, so, a program is prepared for the experiment to calculate pre-encoded pattern or pre-decoded sequence in advance. Then, the calculated pattern is loaded in the error detector to measure the bit error rate.

Differential quadrature phase-shift keying (DQPSK) is one of the most attractive advanced modulation format in these years, because it has a good spectral efficiency. The DQPSK can transmit two bits per symbol, and it has twice the spectral efficiency of the differential phase-shift keying (DPSK). This master thesis focuses on to study the DQPSK performance in the long-haul transmission with the wavelength-division multiplexing system (WDM). The WDM multiplexes multiple optical carriers in the single optical fiber using the different wavelength lasers to carry the signal. For the experiment, the DQPSK needs a little special technique to conduct. When a delay demodulator is used for the DQPSK signal, an encoder or decoder is required to make the received serial data to be the same as the transmitted serial sequence. As an electrical encoder or decoder is difficult to realize, a software to calculate encoded pattern or decoded sequence is prepared for the experiment. Then, calculated pattern is installed into the error detector, and it is used to measure the bit error rate. Finally, the performance of the different channels of the WDM DQPSK transmission is measured experimentally. The transmission distance is 495km for the straight line experimental setup.

La sécurisation des systèmes de communication passe par des techniques de cryptographie à clef. Les communications, sur un canal non protégé, imposent l'échange d'une clef entre Alice et Bob qui sont avec Eve, tentant d'obtenir cette clef à leur insu, les acteurs incontournables de tout scénario cryptographique. La sécurité quantique résulte de l'impossibilité pour Eve de dupliquer les signaux reçus ou d'en distraire une partie significative sans signer son intervention par une modification importante du taux d'erreur des signaux reçus par Bob. Les erreurs résultent d'observations incompatibles d'un même objet quantique, comme la mesure de la phase d'un photon unique sur deux bases différentes. Un faible taux d'erreur garantit la confidentialité de la clef. Le protocole BB84 autorise l'élaboration et l'échange de clef entre Alice et Bob. Il nécessite quatre états quantiques constituant deux bases, notées A1 et A2 contenant chacune deux symboles notés 0 et 1. Les bases A1 et A2 sont dites conjuguées. Cette thèse propose une étude et une réalisation expérimentale d'un système de distribution quantique de clef utilisant le protocole BB84 par codage en phase sur un photon unique (l = 1,5µm). La génération des photons uniques est assurée par un laser de type ILM dont les impulsions optiques sont fortement atténuées. La modulation QPSK satisfaisant à des choix de base et de symbole indépendants est assurée par l'utilisation de modulateurs Mach-Zehnder à deux électrodes. Trois systèmes de détection cohérente sont proposés et comparés. Les évolutions successives de notre système nous amènent à proposer aujourd'hui un système de cryptographie quantique à une voie optique par codage DQPSK.

<p>The main issue of this thesis is making the behaviour model of Bluetooth EDR (enhanced data rate) baseband signal processing. This Bluetooth baseband project is part of the soft defined radio project at electrical engineering department, Linköping University.</p><p>In this project, both the basic rate and EDR model were built and simulated. The GFSK and π/4 DQPSK digital modulation and demodulation were implemented in C code. The BER was tested to evaluate the demodulation results. Furthermore, the error correction (FEC) and the error checking (HEC,CRC) were also implemented according to the Bluetooth standards. The CRC flag was detected to test the payload demodulation results.</p><p>Especially, GFSK and π/4 DQPSK specifications have to be combined with each other at sample rate of ADC.</p><p>Finally, the basic rate and EDR model were simulated to measure the BER and CRC performance.</p><p>From the simulation results, the receiver filter, synchronization and channel condition were three key points in this Bluetooth EDR system implementation.</p><p>So we get further understanding about the Bluetooth system specification and DSP implementation methods.</p>

Nowadays, the long-haul optical fiber communication system is one of the important way to convey the information, and there is strong competition of research in the optical long-haul transmission to achieve high channel bit rates and large transmission capacity. Therefore, it is important to study a technology to improve the performance of such system. The return-to-zero differential phase-shift keying (RZ-DPSK) and the return-to-zero differential quadrature phase-shift keying (RZ-DQPSK) have received renewed attention recently for the long-haul transmission systems, because they can improve the transmission performance of the long-haul system. Furthermore, the design of the dispersion map becomes significantly different from that of the conventional system using the intensity modulation direct detection (IM-DD) scheme. Besides, the RZ-DQPSK can transmit two bits per symbol, so it has twice the spectral efficiency of the RZ-DPSK. This study is focusing on the difference of the transmission performance of the long-haul RZ-DQPSK system due to the dispersion map using the numerical simulation.

The main issue of this thesis is making the behaviour model of Bluetooth EDR (enhanced data rate) baseband signal processing. This Bluetooth baseband project is part of the soft defined radio project at electrical engineering department, Linköping University. In this project, both the basic rate and EDR model were built and simulated. The GFSK and π/4 DQPSK digital modulation and demodulation were implemented in C code. The BER was tested to evaluate the demodulation results. Furthermore, the error correction (FEC) and the error checking (HEC,CRC) were also implemented according to the Bluetooth standards. The CRC flag was detected to test the payload demodulation results. Especially, GFSK and π/4 DQPSK specifications have to be combined with each other at sample rate of ADC. Finally, the basic rate and EDR model were simulated to measure the BER and CRC performance. From the simulation results, the receiver filter, synchronization and channel condition were three key points in this Bluetooth EDR system implementation. So we get further understanding about the Bluetooth system specification and DSP implementation methods.

[pt] Neste trabalho realizamos uma prova da viabilidade de um sistema de comunicação óptica com capacidade de transmissão de 50 Gbit/s em uma largura de banda de 50 GHz utilizando o legado dos sistemas com taxas de 10 Gbit/s. Uma série de configurações experimentais foi testada em uma ordem de complexidade crescente para verificar separadamente as etapas e as técnicas aplicadas para o aumento da capacidade de transmissão de dados e a eficiência espectral. Em alguns casos, a curva característica resultante da configuração backto- back do analisador de taxa de erro de bit média foi utilizada como referência para comparação das configurações experimentais realizadas durante o trabalho. / [en] In this work we perform a proof of feasibility of 50 Gbit/s transmission within a 50 GHz optical bandwidth exploring the 10 Gbit/s legacy. A series of experimental configurations were tested in an order of increasing complexity to verify separately the steps and applied techniques for increasing data transmission capacity and spectral efficiency. In some cases, the comparison of experimental configuration was made using the back-to-back configuration of the Bit Error Rate Tester.

Le trafic dans les réseaux optiques est en constante augmentation depuis de nombreuses années. CISCO affirme qu'il devrait augmenter d'un facteur 13 en 2020. Ceci induit une augmentation de la consommation énergétique et de l'évolution de la taille des réseaux entrainant un accroissement de la complexité des réseaux. Dans ce contexte, pour répondre à l'augmentation du débit dans les réseaux et procure un réseau de télécommunications fiable, il faut prévoir une planification et une ingénierie de réseaux adaptées. Dans ce but, nous étudions dans cette thèse le design d'un nœud de commutation optique ROADM. nous considérons différentes architectures de nœud, composants et sous-systèmes utilisés dans les configurations de nœud RODM "Broadcast and Select" et "Route and Select". Diverses configurations de modules d'insertion/extraction sont analysées ("Colored/colorless, directional/directionless et contentional/contentionless"). Pour ce faire, nous avons développé un simulateur de nœud ROADM dans une plateforme de trafic dynamique et nous avons proposé une stratégie de gestion offline de la contention à l'intérieur du nœud. Nous avons obtenu une réduction du rapport de blocage intra noeud de l'ordre de 1.5. Ensuite, nous nous sommes focalisés sur la planification des futures générations de réseaux optiques métro cœur. Dans ce but, nous avons étudié la possibilité d'une transmission non cohérente à 100 Gb/s en utilisant le format de modulation PDM-DQPSK. Ensuite, nous avons considéré l'implémentation de la PDM-CS-DQPSK. La qualité de transmission de ces deux systèmes a finalement été évaluée / Traffic demand is exponentially increasing in recent years. Cisco forecast claims that by 2020, transport traffic will be 13 times of today's traffic transmission. This incremental traffic demand makes concerns about energy consumption and network scalability as well as increasing the network complexity. In this respect, to adresse the future traffic demand requirement and provide a reliable telecommunication network, precise network planning and engineering are needed. To this aim, we adress the problem of ROADM node design by presenting different architectures, components and subsystems to investigate the Broadcast and Select and Route and Select ROADM node architectures. Colored/colorless, directional/directionless and contentional/contentionless add/drop module configurations are studied. Futhermore, the problem of Intra Node Blocking is investigated by developing a node simulator in a dynamic network traffic platform. In this respect, we propose an offline contention management strategy for an ROADMnode in order to efficiently decrease the Intra Node blocking ration by more than 1.5 order of magnitude. Finally, we focus on network planning by investigating short and medium term network upgrades for metro-core optical network. To this goal, we investigate the possibility of non coherent signal transmission in metro-core segment of hierarchical layered optical network. Quality of transmission for 100 Gbit/s PDM-DQPSK-modulation format is investigated. Then, we propose the implementation of PDM-CS-DQPSK modulation format to transmit 100 Gbit/s signals in ROADM based optical transmission systems

Simulcasting is a spectrally efficient wide area coverage technique that can be advantageous in private mobile radio applications such as emergency services. In a simulcast network, multiple base stations broadcast the same information on a single nominal carrier frequency, causing severe multipath interference at a receiver in the overlap region of several neighboring base stations. In this thesis, we introduce a transmit delay scheme for simulcast networks and investigate the performance of the scheme in LOS and Rayleigh fading environments. In this scheme a relative transmit delay is introduced between neighboring base stations to extend the differential delay between different paths in the overlap regions, from the order of the carrier period to the order of the symbol period, thus transform RF carrier interference into ISI. The receiver employs MLSE to obtain diversity gain from ISI. The performance of the system is evaluated using analytical bounds and simulations carried out for an MLSE based &amp / #960 / /4 DQPSK receiver and the results show that the proposed scheme operates succesfully, turning destructive interference disadvantage into a multipath diversity advantage, provided that a sufficient delay is used between the base stations. The &ldquo / sufficient&rdquo / delay value is determined by considering the coverage properties of the scheme and is in fact &ldquo / optimum&rdquo / , since more than sufficient transmit delays result in useless increased receiver complexity. We provide our results using parameters for the TETRA system, however, the results of the work can readily be used for other systems.