Next Generation Passive Optical Network Based On Orthogonal Frequency Division Multiplexing

In recent decades, the industry of communications has acquired huge significance, and nowadays constitutes an essential tool for the society information. Thus, the exponential growth in demand of broadband services and the increasing amount of information to be transmitted have spurred the evolution of the access network infrastructure to effectively meet the user needs in an effective way in terms of costs of both installation and maintenance. Passive optical networks (PON) are currently considered the most efficient and least costly alternative to deploy fiber to the home environment. In order to allow many users simultaneously coexist PONs based on time multiplexing (TDMA) have been developed. Looking ahead, however, it is expected that these techniques do not meet the requirements on access networks. In consequence, other multiple access techniques such as Wavelength Division Multiplexing Access (WDMA) or Orthogonal Frequency Division Multiplexing Access (OFDMA) are currently under study and development for use in the next generation of PONs. Particularly, in recent years OFDM has stood out among the scientific community to be considered a solution with great potential on future implementation of PONs. This is especially true due to the capacity of OFDM to work with multilevel modulations, its high tolerance to chromatic dispersion, and its high flexibility and granularity in terms of bandwidth management. Given the above, the aim of this Thesis is to study deeply the advantages and challenges of implementing the standard OFDM as an access network solution; likewise, it offers solutions to improve its performance. In order to evaluate the main structures and strategies for OFDM-based PON, a comparative analysis of all of them is performed firstly, highlighting their sensitivity levels, maximum range and number of users. A key aspect for network providers is the cost of operation, deployment and maintenance of networks. As a low-cost solution, this Thesis proposes a network model called Statistical-OFDMA-PON based on intensity modulation and direct detection. In addition, dynamic bandwidth management strategies are applied into this model getting an improvement in the power balance which in turn, allows to increase the maximum range and the scalability in number of users. One of the main OFDM problems is the Peak-to-Average Power Ratio (PAPR) which increases with the number of carriers. This thesis proposes a new algorithm based on folding the signal and transmitting auxiliary information in order to compensate the PAPR effect and thus increase the sensitivity of the optical system. On the other hand, OFDMA requires a large number of operations in the digital domain resulting in a high computational effort, which in turn results in an increased cost. For this reason, this Thesis presents a study on the optimization of the required resolution in the Digital-to-Analog / Analog-to-Digital Converters (DAC/ADCs) maintaining the transmission quality. The optimization of the computation time may make the OFDMA-based optical network more attractive for future PONs. Finally, another problem concerning the OFDM optical networks is their sensitivity to Phase Noise (PN). In this regard, this Thesis presents a study of the effect of the laser linewidth and its dependence on signal bandwidth. A mitigation technique based on pilot tones is implemented and the limiting values for the laser linewidth are found to be within the reach of present low-cost light sources.

[ANGLÈS] Research activities for new alternatives in ultra fast transmission over optical fiber networks are looking towards Orthogonal Frequency Division Multiplexing (OFDM) which is used in different modern communication systems such as LTE, WiFi or WiMax because of the following reasons: tolerance to channel limitations, better spectral exploitation, scalability, flexibility and implementation feasibility with state of the art electronics. These benefits have been subject of major interest in Passive Optical Networks (PONs), which depend on reliable but low cost solutions to be commercialized. The adaptation of OFDM as an access scheme in PONs with cost effective Intensity Modulation with Direct Detection (IM/DD) can potentially deliver these benefits and be a next step in the evolution of high volume data access networks. The flexibility given by OFDM is applied as bandwidth granularity for the users in such way that each of them will be guaranteed with a certain level of service, yet the reconfigurability capabilities and bandwidth assignment for different users in a Optical Orthogonal Frequency Division Multiplexed Access (O-OFDMA) PON must be properly understood. The work reports the development of a test bed on IM/DD O-OFDMA for next generation PONs, in particular studying bandwidth assignment for different users for future Dynamic Bandwidth Allocation strategies.

This book focuses on recent research and developments on optical communications. The chapters present different aspects of optical communication systems, comprising high capacity transmission over long distances, coherent and intensity modulated technologies, orthogonal frequency-division multiplexing, ultrafast switching techniques, and photonic integrated devices. Digital signal processing and error correction techniques are also addressed. The content is of interest to graduate students and researchers in optical communications.

Fibre-to-the-Home networks constitute a fundamental telecom segment with the required potential to match the huge capacity of transport networks with the new user communication demands. Huge investments in access network infrastructure are expected for the next decade, with many initiatives already launched around the globe recently, driven by the new broadband service demands and the necessity by operators to deploy a future-proof infrastructure in the field. Dense FTTH Passive Optical Networks (PONs) is a cost-efficient way to build fibre access, and international standards (G/E-PON) have been already launched, leading to new set of telecom products for mass deployment. However, these systems only make use of less than 1% of the optical bandwidth; thus, relevant research is taking place to maximize the capacity of these systems, with the latest opto-electronic technologies, demonstrating that the huge bandwidth available through the fibre access can be exploited in a cost-efficient and reliable manner. Next-Generation FTTH Passive Optical Networks gathers and analyzes the most relevant techniques developed recently on technologies for the next generation FTTH networks, trying to answer the question: what’s after G/E-PONs?

[ANGLÈS] A cost-effective architecture for next-generation passive optical networks is designed and dimensioned, based on intensity modulation and direct detection optical orthogonal frequency division multiple access.

The first book on optical OFDM by the leading pioneers in the field The only book to cover error correction codes for optical OFDM Gives applications of OFDM to free-space communications, optical access networks, and metro and log haul transports show optical OFDM can be implemented Contains introductions to signal processing for optical engineers and optical communication fundamentals for wireless engineers This book gives a coherent and comprehensive introduction to the fundamentals of OFDM signal processing, with a distinctive focus on its broad range of applications. It evaluates the architecture, design and performance of a number of OFDM variations, discusses coded OFDM, and gives a detailed study of error correction codes for access networks, 100 Gb/s Ethernet and future optical networks. The emerging applications of optical OFDM, including single-mode fiber transmission, multimode fiber transmission, free space optical systems, and optical access networks are examined, with particular attention paid to passive optical networks, radio-over-fiber, WiMAX and UWB communications. Written by two of the leading contributors to the field, this book will be a unique reference for optical communications engineers and scientists. Students, technical managers and telecom executives seeking to understand this new technology for future-generation optical networks will find the book invaluable. William Shieh is an associate professor and reader in the electrical and electronic engineering department, The University of Melbourne, Australia. He received his M.S. degree in electrical engineering and Ph.D. degree in physics both from University of Southern California. Ivan Djordjevic is an Assistant Professor of Electrical and Computer Engineering at the University of Arizona, Tucson, where he directs the Optical Communications Systems Laboratory (OCSL). His current research interests include optical networks, error control coding, constrained coding, coded modulation, turbo equalization, OFDM applications, and quantum error correction. "This wonderful book is the first one to address the rapidly emerging optical OFDM field. Written by two leading researchers in the field, the book is structured to comprehensively cover any optical OFDM aspect one could possibly think of, from the most fundamental to the most specialized. The book adopts a coherent line of presentation, while striking a thoughtful balance between the various topics, gradually developing the optical-physics and communication-theoretic concepts required for deep comprehension of the topic, eventually treating the multiple optical OFDM methods, variations and applications. In my view this book will remain relevant for many years to come, and will be increasingly accessed by graduate students, accomplished researchers as well as telecommunication engineers and managers keen to attain a perspective on the emerging role of OFDM in the evolution of photonic networks." -- Prof. Moshe Nazarathy, EE Dept., Technion, Israel Institute of Technology The first book on optical OFDM by the leading pioneers in the field The only book to cover error correction codes for optical OFDM Applications of OFDM to free-space communications, optical access networks, and metro and log haul transports show optical OFDM can be implemented An introduction to signal processing for optical communications An introduction to optical communication fundamentals for the wireless engineer

The desire for high bandwidth multi-media reach content and the exponential growth of Internet traffic has led to the penetration of optical technologies into the access segment in the form of Fibre-To-The-x (FFT-x) topologies. Due to its cost effectiveness and low energy consumption, most FFT-x models have been based on Passive Optical Networks (PONs) where the employment of in-line active components has been discouraged. Next generation optical access networks are required to provide higher bandwidth-distance product and support wireless services in a cost effective manner. Through experimental and simulation work, this thesis examines the use of multicarrier modulation formats such as Orthogonal Frequency Division multiplexing (OFDM) and Filter Bank Multi Carrier (FBMC) as mans of helping to meet the bandwidth-distance requirements set for next generation optical access networks. OFDM and FBMC both exhibit high spectral efficiency and a tolerance to chromatic dispersion making them excellent candidates for use in next generation optical access networks. In order to promote cost efficiency these systems are also studied in conjunction with Direct Modulation of novel laser devices and direct detection. In this work, the accommodation of Long Term Evolution (LTE) services in hybrid wired/wireless optical access networks is also demonstrated using spectral notching either by deactivation of subcarriers in OFDM or line-coding techniques in OOK based wired services. The use of FBMC and OFDM is also studied in light of uplink transmission in optical access networks without the employment of spectral guard bands that is commonly used for the reduction of Multiple Access Interference (MAI).