Download or read book Orthogonal Frequency Division Multiplexing Access Based Passive Optical Network written by Cheng Li and published by . This book was released on 2009 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Next Generation Passive Optical Networks Based on Orthogonal Frequency Division Multiplexing Techniques written by Francesc Xavier Escayola Elias and published by . This book was released on 2016 with total page 257 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Next Generation Passive Optical Network Based on Orthogonal Frequency Division Multiplexing written by Alabbas Ahmed Abduljabbar and published by . This book was released on 2016 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Orthogonal Frequency Division Multiplexed Access for Passive Optical Networks written by Ángel Peralta Gallardo and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: [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.

Download or read book A Novel Multi band CO OFDM Based Long Reach Passive Optical Network Architecture written by Mohamed Ben Zeglam and published by . This book was released on 2017 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: The thesis investigates a new long-reach passive optical networks (LRPON) architecture based on multi-band coherent optical orthogonal frequency division multiplexing (CO-OFDM). The proposed CO-OFDM based LRPON system is characterized by a novel phase noise compensation mechanism aiming to deal with optical signal dispersion in long-range transmissions. By employing a dispersion compensating fiber (DCF) and local oscillator (LO) laser phase shifter for each end-to-end transmission between OLT and ONU, we will show the phase noise due to dispersion can be effectively mitigated. Simulation of the downlink traffic between one optical line terminal (OLT) and 12 optical network units (ONUs) is performed successfully at different fiber lengths, at the data rate of 10$Gbps$ per ONU. The required BER for the forward error correction (FEC) has been achieved for most ONUs, using a dispersion compensating fiber (DCF) and local oscillator (LO) laser phase shifter to compensate for the chromatic dispersion (CD) and the polarization mode dispersion (PMD), respectively.

Download or read book Design and Analysis of Adaptively Modulated Optical Orthogonal Frequency Division Multiple Access Multiband Passive Optical Networks written by J. T. Groenewald and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book OFDM for Optical Communications written by William Shieh and published by Academic Press. This book was released on 2009-09-18 with total page 457 pages. Available in PDF, EPUB and Kindle. Book excerpt: - 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

Download or read book Predistortion Transmitters for Orthogonal Frequency Division Multiplexing Passive Optical Networks written by Mireia Liebana Buxó and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of this work is to offer different alternatives for an OFDM PON networks, studying and analyzing many systems with their pros and cons and proposing news schematics for a multiuser scenario for the uplink. The systems analyzed are composed by an optical I/Q transmitter and two types of receivers, a DD and a hybrid 90o coherent receiver. A new technique, called predistortion, that improves the drawbacks of the conventional oIQ systems is studied. The idea to perform the multiuser scenario is shifting the user data, allowing allocation of each user in a given optical spectral band. All the simulations have been done using the commercial software VPItransmissionMakerTM and VPIphotonicsAnalyzerTM, (VPI) in combination with a code in Matlab for the OFDM coder and decoder. Also the performance of the optical OFDM systems is measured by means of a script in TCL/TK language that allows changing many parameters, in order to test and obtain results of the systems performance in terms of sensitivity vs. length for a threshold minimum quality BER value of 10-3.

Download or read book Optical Orthogonal Frequency Division Systems with Direct Detection Receivers written by Juan Miguel Pérez Rosas and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: [ANGLÈS] The new generation of Pasive Optical Networks (PONs) to cover the last-mile to the user, is today a hot topic of research. Stringent performance requirements are both capacity and reach; these, together with reduced cost lead to consideration of a new paradigm. In this context, Optical OFDM (O-OFDM) is regarded as a promising candidate. From the many architectures being proposed for O-OFDM, the use of Direct Detection is particularly interesting for the downlink of Passive Optical Networks as cost-efficient Optical Network Units (ONUs) are required. In this line, this work encompasses a general study of Direct Detection Optical OFDM (DD O-OFDM) communications systems with emphasis on applications to optical Access Networks. It proposes designs for the downstream links of three different access network topologies differentiated by the optical modulation used: an Intensity Modulation (IM) with a Directly Modulated Laser (DML) an IM with a Mach-Zehnder Modulator (MZM) and an Amplitude modulation also with a MZM. All systems are based on Direct Detection receivers and the transmission of O-OFDM signals. The architectures, establish a wavelength agnostic link by transmitting Double Side Band signals. The impairments of a DSB transmission are studied and parting from them an optimization on the network?s parameters of frequency Guard Band and Carrier to Signal Power Ratio is performed. In order to test the architectures and optimize the parameters, simulations were executed using the commercial software VPI Transmission Maker TM. The testing of the architectures was done by minimizing receiver sensitivity at a BER 10-3 for data rates of 10Gbps and 40Gbps using 4-QAM and 16-QAM respectively, as digital modulation formats. Results show that spectral occupancy of the O-OFDM signal and the CSPR can be optimized while at the same time compensating for DSB impairments such as amplitude fading. Also the advantages and disadvantages of each optical modulation format depending on data rates and link?s distances required as well as cost-effectiveness are tested and described.

Download or read book Optical Communications written by Alberto Paradisi and published by Springer. This book was released on 2018-09-04 with total page 271 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Integrated Distribution of Wireless and Wired Services Using a Passive Optical Fibre Network written by Arsalan Saljoghei and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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).

Download or read book Orthogonal Frequency Division Multiplexing for Optical Access Networks written by O. O. Omomukuyo and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Orthogonal Frequency Division Multiplexing Based Medium Access Under Rate Constraints written by Thomas Deckert and published by Jörg Vogt Verlag. This book was released on 2007 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Orthogonal Frequency Division Multiplexing for Optical Access Networks written by Oluyemi Omololu Omomukuyo and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Optical Code Division Multiple Access written by Ken-ichi Kitayama and published by Cambridge University Press. This book was released on 2014-04-10 with total page 361 pages. Available in PDF, EPUB and Kindle. Book excerpt: A self-contained guide to OCDMA for Next-Generation FTTH systems, from the fundamentals to cutting-edge research and practical perspectives.

Download or read book Orthogonal Frequency division Multiplexing for Optical Communications written by Daniel Jose Fernandes Barros and published by Stanford University. This book was released on 2011 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: The drive towards higher spectral efficiency and maximum power efficiency in optical systems has generated renewed interest in the optimization of optical transceivers. In this work, we study the different optical applications: Wide Area Networks (WANs), Metropolitan Area Networks (MANs), Local Area Networks (LANs) and Personal Area Networks (PANs). In WANs or long-haul systems, orthogonal frequency-division multiplexing (OFDM) can compensate for linear distortions, such as group-velocity dispersion (GVD) and polarization-mode dispersion (PMD), provided the cyclic prefix is sufficiently long. Typically, GVD is dominant, as it requires a longer cyclic prefix. Assuming coherent detection, we show how to analytically compute the minimum number of subcarriers and cyclic prefix length required to achieve a specified power penalty, trading off power penalties from the cyclic prefix and from residual inter-symbol interference (ISI) and inter-carrier interference (ICI). We derive an analytical expression for the power penalty from residual ISI and ICI. We also show that when nonlinear effects are present in the fiber, single-carrier with digital equalization outperforms OFDM for various dispersion maps. We also study the impairments of electrical to optical conversion when using Mach-Zehnder (MZ) modulators. OFDM has a high peak-to-average ratio (PAR), which can result in low optical power efficiency when modulated through a Mach-Zehnder (MZ) modulator. In addition, the nonlinear characteristic of the MZ can cause significant distortion on the OFDM signal, leading to in-band intermodulation products between subcarriers. We show that a quadrature MZ with digital pre-distortion and hard clipping is able to overcome the previous impairments. We consider quantization noise and compute the minimum number of bits required in the digital-to-analog converter (D/A). Finally, we discuss a dual-drive MZ as a simpler alternative for the OFDM modulator, but our results show that it requires a higher oversampling ratio to achieve the same performance as the quadrature MZ. In MANs, we discuss the use OFDM for combating GVD effects in amplified direct-detection (DD) systems using single-mode fiber. We review known direct-detection OFDM techniques, including asymmetrically clipped optical OFDM (ACO-OFDM), DC-clipped OFDM (DC-OFDM) and single-sideband OFDM (SSB-OFDM), and derive a linearized channel model for each technique. We present an iterative procedure to achieve optimum power allocation for each OFDM technique, since there is no closed-form solution for amplified DD systems. For each technique, we minimize the optical power required to transmit at a given bit rate and normalized GVD by iteratively adjusting the bias and optimizing the power allocation among the subcarriers. We verify that SSB-OFDM has the best optical power efficiency among the different OFDM techniques. We compare these OFDM techniques to on-off keying (OOK) with maximum-likelihood sequence detection (MLSD) and show that SSB-OFDM can achieve the same optical power efficiency as OOK with MLSD, but at the cost of requiring twice the electrical bandwidth and also a complex quadrature modulator. We compare the computational complexity of the different techniques and show that SSB-OFDM requires fewer operations per bit than OOK with MLSD. In LANs, we compare the performance of several OFDM schemes to that of OOK in combating modal dispersion in multimode fiber links. We review known OFDM techniques using intensity modulation with direct detection (IM/DD), including DC-OFDM, ACO-OFDM and pulse-amplitude modulated discrete multitone (PAM-DMT). We describe an iterative procedure to achieve optimal power allocation for DC-OFDM, and compare analytically the performance of ACO-OFDM and PAM-DMT. We also consider unipolar M-ary pulse-amplitude modulation (M-PAM) with minimum mean-square error decision-feedback equalization (MMSE-DFE). For each technique, we quantify the optical power required to transmit at a given bit rate in a variety of multimode fibers. For a given symbol rate, we find that unipolar M-PAM with MMSE-DFE has a better power performance than all OFDM formats. Furthermore, we observe that the difference in performance between M-PAM and OFDM increases as the spectral efficiency increases. We also find that at a spectral efficiency of 1 bit/symbol, OOK performs better than ACO-OFDM using a symbol rate twice that of OOK. At higher spectral efficiencies, M-PAM performs only slightly better than ACO-OFDM using twice the symbol rate, but requires less electrical bandwidth and can employ analog-to-digital converters at a speed only 81% of that required for ACO-OFDM. In PANs, we evaluate the performance of the three IM/DD OFDM schemes in combating multipath distortion in indoor optical wireless links, comparing them to unipolar M-PAM with MMSE-DFE. For each modulation method, we quantify the received electrical SNR required at a given bit rate on a given channel, considering an ensemble of 170 indoor wireless channels. When using the same symbol rate for all modulation methods, M-PAM with MMSE-DFE has better performance than any OFDM format over a range of spectral efficiencies, with the advantage of M-PAM increasing at high spectral efficiency. ACO-OFDM and PAM-DMT have practically identical performance at any spectral efficiency. They are the best OFDM formats at low spectral efficiency, whereas DC-OFDM is best at high spectral efficiency. When ACO-OFDM or PAM-DMT are allowed to use twice the symbol rate of M-PAM, these OFDM formats have better performance than M-PAM. When channel state information is unavailable at the transmitter, however, M-PAM significantly outperforms all OFDM formats. When using the same symbol rate for all modulation methods, M-PAM requires approximately three times more computational complexity per processor than all OFDM formats and 63% faster analog-to-digital converters, assuming oversampling ratios of 1.23 and 2 for ACO-OFDM and M-PAM, respectively. When OFDM uses twice the symbol rate of M-PAM, OFDM requires 23% faster analog-to-digital converters than M-PAM but OFDM requires approximately 40% less computational complexity than M-PAM per processor.

Download or read book Orthogonal Frequency Division Multiple Access Fundamentals and Applications written by Tao Jiang and published by Auerbach Publications. This book was released on 2019-08-30 with total page 660 pages. Available in PDF, EPUB and Kindle. Book excerpt: Supported by the expert-level advice of pioneering researchers, Orthogonal Frequency Division Multiple Access Fundamentals and Applications provides a comprehensive and accessible introduction to the foundations and applications of one of the most promising access technologies for current and future wireless networks. It includes authoritative coverage of the history, fundamental principles, key techniques, and critical design issues of OFDM systems. Covering various techniques of effective resource management for OFDM/OFDMA-based wireless communication systems, this cutting-edge reference: Addresses open problems and supplies possible solutions Provides a concise overview of key techniques for adaptive modulation Investigates radio channel modeling in OFDMA-based wireless communication systems Details detection strategies of frequency-domain equalization for broadband communications Introduces a novel combination of OFDM and the orbital angular momentum of the electromagnetic field to improve performance Contains extensive treatment of adaptive MIMO beamforming suitable for multiuser access This valuable resource supplies readers with a macro-level understanding of OFDMA and its key issues, while providing a systematic manual for those whose work is directly related to practical OFDMA and other multiuser communication systems projects.