This book is concerned with high bit rate systems, which are predestined particularly for the long-distance trunk lines that will be used in future communications networks.

This book is concerned with high bit rate systems, which are predestined particularly for the long-distance trunk lines that will be used in future communications networks.

This volume contains the proceedings of the NOC 2001 at Adastral park, UK, June 26-29 2001. With about 70 papers, this book highlights the gigabit ethernet PON developments, and other work on standard broadband PONs such as, dynamic bandwith assignment. There are 10 papers on optical packet switiching and work on optical cross-connects and DWDM for long-haul systems is presented.

Digital transmission systems are the backbone of modern communication networks, enabling the exchange of information across various media, such as copper wires, optical fibers, radio waves, and satellites. These systems use digital signals to encode, transmit, and decode data, such as voice, video, text, and images. Digital transmission systems have many advantages over analog systems, such as higher capacity, better quality, lower cost, and more flexibility. However, designing and implementing digital transmission systems is not a trivial task. It requires a solid understanding of the fundamental principles, techniques, and standards that govern the operation and performance of these systems. It also requires a familiarity with the various technologies and components that are used to realize these systems, such as modulation, multiplexing, coding, switching, amplification, and synchronization. This book aims to provide a comprehensive and up-to-date introduction to the fundamentals of digital transmission systems, covering both theoretical and practical aspects. It is intended for students, engineers, and researchers who want to learn the basics of digital transmission systems, as well as for professionals who want to refresh or update their knowledge in this field. The book is also important for communication engineers and operators who are involved in the planning, design, installation, operation, maintenance, and troubleshooting of digital transmission systems and networks. The book covers the most common and widely used standards and technologies in digital transmission, such as PCM, PDH, SDH, OTN, WDM, ADSL, GPON, and radio waves. The book also provides the latest information on the evolution and trends of digital transmission, such as liquid OTN, fiber-optic transmission systems, and digital transmission networks. The book helps communication engineers and operators to understand the principles, advantages, limitations, and challenges of digital transmission systems and to apply them to their specific needs and scenarios. The book is organized into eight chapters, each covering a major topic in digital transmission systems. The chapters are as follows: Chapter 1 introduces the importance, motivations, and overview of digital transmission systems, and provides a conclusion and some questions for review. Chapter 2 explains the fundamentals of pulse code modulation (PCM), which is the most common technique for converting analog signals into digital signals. It also describes the structure and signaling of the 2 Mbit/s (E1) frame, which is the basic unit of transmission in many digital systems. Chapter 3 discusses the plesiochronous digital hierarchy (PDH), which is a legacy standard for multiplexing and transporting digital signals over copper wires or optical fibers. It also covers the frame structure, synchronization, signaling, error detection and correction, network architecture, and limitations of PDH. Chapter 4 introduces the synchronous digital hierarchy (SDH), which is a more advanced and widely adopted standard for multiplexing and transporting digital signals over optical fibers. It also covers the general and specific frame structures, multiplexing hierarchy, network and management, network protections, and synchronization of SDH. Chapter 5 presents optical fiber technology, which is the main medium for transmitting digital signals over long distances and at high speeds. It also covers the technical overview, physics of light, and design and protection of fiber optic cables. Chapter 6 explores the wavelength division multiplexing (WDM) technology, which is a technique for increasing the capacity and efficiency of optical fiber networks by using multiple wavelengths of light. It also covers the WDM and optical fiber structure, active and passive optical components, optical amplification, noise calculation, fiber-optic transmission systems, and fiber-optic networks. Chapter 7 describes the optical transport network (OTN), which is a standard for multiplexing and transporting various types of digital signals over optical fibers using a common format. It also covers the OTN fundamentals, multiplexing overview, frame structure, evolution to liquid OTN, and important topics in OTN. Chapter 8 reviews the ADSL modems, GPON fundamentals, and radio waves propagations, which are some of the technologies and phenomena that are related to digital transmission systems. The book also includes two appendices that provide some supplementary information on BIP, SDH Synchronization, OTN protection and more. The book assumes that the reader has some basic knowledge of mathematics, physics, and electronics, as well as some familiarity with communication systems and networks. The book provides clear explanations, examples, figures, tables, and equations to illustrate the concepts and methods of digital transmission systems. The book also provides questions at the end of each chapter to test the reader’s understanding and to stimulate further exploration. The book is written by who is a Doctor of Electrical Engineering, Egypt. Ayman Elmassarawy has a PhD in communication systems and has over 20 years of research and practical experience in the field of digital transmission systems in the field of digital transmission systems. The book is a valuable resource for anyone who wants to learn the fundamentals of digital transmission systems and to gain a deeper insight into the current and emerging technologies and standards in this field. The book is also a useful reference for anyone who is involved in the design, implementation, operation, or maintenance of digital transmission systems and networks.

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.