bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optical Fiber Local Area Networks
Authors: Shadaram Mehdi , Gonzalez‐Lozano Virgilio E. 
Published: November 2003

Abstract
Communication between computers is an essential part of modern living and the telecommunication industry is one of world's fastest growing. There is an increasing demand for higher bandwidth, almost doubling the data rate every year. This has reached a point where a single transmission medium such as twisted pair or coaxial cable is not capable of transmitting the load. Thus, for a reliable and high‐speed data transfer, computers are connected through a network of point‐to‐point communication links. These types of networks usually referred to as local area network or LAN. The main purpose of a LAN is to share resources such as files, printers, programs, databases, etc; among the nodes in the network. The initial designs were intended for communication between computers at short distances; however, the length of the links has grown from a few meters to a few kilometers. If computers are connected via optical fiber links, the LAN is referred to as optical fiber LAN. Since the early 1970s optical fibers have been utilized as transmission media in long and short distance communication links. The capacity of optical fibers has increased from several Mbit/sec per km to about 300 Gbit/sec per km; and could reach thousands of Gbit/sec in the near future. Other properties like small size, lightweight, and immunity to electromagnetic interference noise also provide a crucial advantage for optical fibers over other mediums. Some common types of Optical LANs are FDDI, optical Ethernet at various speeds, Fibre Channel and ATM LAN emulation.
Image Compression
Authors: Mertins Alfred 
Published: November 2003

AbstractThe aim of this article is to give an overview of some of the most important image compression tools and techniques. We start by looking at the theoretical background of data compression and describe source coding as a tradeoff between compression ratio and fidelity. Subsequently we explain the principles of PCM, DPCM, transform coding, vector quantization and entropy coding. Then we present the discrete cosine and wavelet transforms, which are the two most important transforms in image compression. Following a discussion of state‐of‐the‐art embedded wavelet compression methods, we review the JPEG, JPEG‐LS, and JPEG2000 standards for the compression of continuous‐tone images.
Partial‐Response Signals for Communications
Authors: Rizos Apostolos 
Published: November 2003

AbstractPartial response signaling is a technique where correlation is introduced between successive transmitted symbols in a communications system. The purpose of this correlation is to give favorable spectral properties to the signal, so that it can match the channel characteristics or satisfy bandwidth requirements. The correlation between symbols, which is a form of (controlled) intersymbol interference, requires relatively complex receiver techniques, like MLSE (maximum likelihood sequence estimation), in order to minimize performance losses. The MLSE complexity had initially restricted the range of practically implementable PR systems to simple schemes like duobinary or modified duobinary. However, with the increased computational power that modern electronic circuits offer, these receiver techniques have feasible implementation now and this has led to a wider use of more complex partial response systems, in applications such as magnetic recording and bandwidth‐efficient twisted pair line transmission.
Broadband Wireless Access
Authors: Sari Hikmet 
Published: November 2003

Abstract
Broadband wireless access (BWA) is an access technology that is particularly suited to new operators without an existing infrastructure to serve the end users. It is in direct competition with incumbent telecom operators' digital subscriber lines (DSL) and cable operators' cable modem technology. BWA systems make use of millimeter‐wave radio frequencies above 20 GHz as well as of microwave frequencies between 2 and 11 GHz. BWA systems at millimeter‐wave frequencies are often referred to as Local Multipoint Distribution Service (LMDS) systems. While LMDS systems are designed for line‐of‐sight (LOS) propagation and use small cell sizes, BWA access systems at lower microwave frequencies are designed for non‐LOS propagation and typically use much larger cell sizes. In this article, we present the basic characteristics of both types of BWA networks, describe the technologies used and the current standardization work in this field by the IEEE 802.16 Group in the US and the ETSI in Europe.
High‐Speed Photodetectors for Optical Communications
Authors: Selim Ünlü M. , Dosunmu Olufemi , Emsley Matthew 
Published: November 2003

AbstractAbstract for “High‐Speed Photodetectors for Optical Communications”We discuss the fundamental properties, basic requirements and limitations of photodetectors pertaining to applications in high‐speed optical communications. The requirements for high‐speed photodetectors include high responsivity at the communication wavelengths, compatible size for coupling to optical fibers as well as low cost and reliability. There are fundamental limitations for high‐speed operation and trade‐offs between various performance parameters for photodetectors. We review these limitations, including those due to capacitance charging and the transit‐time of photogenerated carriers, and present examples of state‐of‐the‐art devices. Although there exists a wide range of photodetectors suitable for optical communications, we will focus on a particular subset of photovoltaics called photodiodes. Several different types of photodiodes will be introduced, including the PIN, Schottky, avalanche and metal‐semiconductor‐metal (MSM) photodiode, along with their individual strengths and weaknesses. In addition, detectors such as the resonant cavity enhanced (RCE) and waveguide photodiode, designed to overcome many of the fundamental limitations associated with conventional structures, are also presented.
Land‐Mobile Satellite Communications*
Authors: Schodorf Jeffrey B. 
Published: November 2003

AbstractLand mobile satellite communications systems are discussed. Topics covered include a brief description of current and future LMSC systems characteristics, an overview of the LMSC propagation channel, error mitigation strategies, multiple access schemes, and network aspects. Most topics are covered in moderate detail with relevant equations and illustrative figures. Major references are also included so that topics of interest can be pursued in more depth by interested readers.
Packet‐Switched Networks
Authors: Stiliadis Dimitrios 
Published: November 2003

AbstractPacket switching is replacing circuit‐switching as the dominant technology in networking. Communication in packet switched networks is enabled through an exchange of messages. Each message is carried over one or multiple packets, and packets from multiple users are interleaved on the same links. Because of the bursty nature of data communications, packet switching offers several advantages in terms of link utilization and delay behavior. In this article, we outline the fundamental concepts of packet switching, such as statistical multiplexing, forwarding and routing, and layered protocol design. We also show how these concepts apply to the Internet that is the most popular packet switched network.
Iterative Detection Algorithms in Communications
Authors: Chugg Keith M. 
Published: November 2003

AbstractThis article motivates the use of algorithms that exchange and update soft decision information in order to improve the performance or reduce the complexity of digital communication receivers. A general and standard approach to the design of such algorithms is then described based on concepts from decision theory and conventional receiver design. A condition for the optimality of this approach is given and motivation for its effectiveness in the absence of this condition is provided. Specific applications of this general approach are summarized.
Convolutional Codes
Authors: Wesel Richard D. 
Published: November 2003

Abstract
Convolutional codes represent one technique within the general class of channel codes. Channel codes (also called error correction codes) permit reliable communication of an information sequence over a channel that adds noise, introduces bit errors, or otherwise distorts the transmitted signal. This article introduces the fundamental aspects of convolutional codes. A discussion of encoder structure introduces shift register diagrams, state diagrams, equivalent encoders, minimal encoders, and catastrophic encoders. Then, trellis diagrams provide the foundation for a description of both maximum likelihood and finite‐traceback implementations of Viterbi decoding. Viterbi decoding provides one technique for computing free distance, which is a first order metric of encoder performance. Finally, the article presents the generating function method for enumerating error events and shows how it may be used in union bounds on bit error rate that are accurate at high SNR.
Acoustic Echo Cancellation
Authors: Hänsler Eberhard 
Published: November 2003

AbstractThis article explains the problem of acoustical echoes and their cancellation. It focuses on the hands‐free telephone as one of the major applications for echo cancelling devices. Beginning with a short discussion of a system formed by a loudspeaker and a microphone located within the same enclosure, the properties of speech signals and noise are described. The major part of the echo can be cancelled by an adaptive filter connected in parallel to the loudspeaker and the microphone. Residual echoes are suppressed by an additional filter within the outgoing signal path. Algorithms for the adaptation of the echo cancelling filter are described. Because of its robustness and its low computational complexity the NLMS algorithm is primarily applied. Measures to improve the speed of convergence and to avoid divergence in case of double talk or strong local noise are discussed. Echo cancellation for stereophonic systems, cancellation in subbands, and the applications of block processing techniques conclude the article.
Pulse Amplitude Modulation
Authors: Bjerke Bjørn A. 
Published: November 2003

Abstract
Pulse amplitude modulation (PAM) is a modulation method used in digital communication systems to facilitate transmission of digital information. The modulation method is used in baseband as well as carrier‐modulated systems. A PAM modulator maps binary information (bits) into analog waveforms which differ only in amplitude. In this article, we provide a mathematical description of PAM signals. This description is used for investigating their spectral characteristics and is also the foundation for discussing the various elements of PAM receivers. In particular, we consider PAM signal demodulation and detection and give a brief overview of carrier recovery and symbol synchronization.
Wireless Local Loop Standards and Systems
Authors: Hashemi Homayoun 
Published: November 2003

AbstractIn this tutorial presentation basic principles and applications of Wireless Local Loops (WLL) systems are reviewed. WLL Technology is described and major mobile‐radio based and proprietary radio interface standards are explored. Spectrum and capacity issues of WLL based on cellular radio principles are presented, and economic aspects of wired and wireless loops are compared. Broadband applications of WLL are also briefly outlined.
Modeling and Analysis Of Digital Optical Communications Systems
Authors: Shtaif Mark 
Published: November 2003

AbstractThis article reviews the modeling and operation of digital optical communications systems focusing on the description of fundamental physical principles and their mathematical representation. It covers issues related to optical amplification and noise, detection and estimation of error‐rates, propagation in optical fibers in the presence of dispersion and nonlinear effects and includes a brief introduction to polarization related phenomena.
Optical Wireless Laser Communications: Free‐Space Optics
Authors: Killinger Dennis 
Published: November 2003

AbstractA brief overview of the technical and scientific basis for Free Space Optics Laser Communication for point‐to‐point laser beam telecommunication through the atmosphere is covered in this chapter. Subjects include the historical background of Free Space Optics (FSO), current commercial applications, laser and LED optical sources, atmospheric scatter and attenuation, optical detectors and noise considerations, the FSO Range Equation with examples of several commercial units, atmospheric refractive turbulence effects, telescope design and alignment problems, and eye safety considerations.
JPEG2000Image Coding Standard
Authors: Usevitch B. E. 
Published: November 2003

AbstractJPEG2000 is a new international image compression standard developed to address some of the shortcomings of the original JPEG standard. JPEG2000 delivers lossy and lossless image compression using the same wavelet based algorithms. A key feature of JPEG2000 is that it produces a very flexible bit stream by only coding the image data once. This bit stream can be rearranged such that sequential decoding gives images of progressively larger size, higher quality, or more colors. All the resultant bit streams maintain a strict embedded property such that truncation of the bit streams gives optimal compressed representations for the given truncated length.
Cochannel Interference in Digital Cellular
TDMA
Networks
Authors: Glisic Savo G. , Pirinen Pekka 
Published: November 2003

Abstract
This Chapter focuses on co‐channel interference in cellular TDMA networks. Both the generation of co‐channel interference and the appropriate interference suppression methods are considered. Contributions of frequency reuse,spatial filtering and time domain interference cancellation on the residual interference are described. Effects of variable propagation parameters (especially lognormal shadowing),cluster sizes and interference parameters to the outage probability are illustrated. Furthermore, the spectrum efficiency examples are shown in the form of the Erlang capacity at variable cluster sizes and quality‐of‐service criteria.
Satellites in
IP
Networks
Authors: Jamalipour Abbas 
Published: November 2003

Abstract
A satellite has been an important element of telecommunications networks for many years, providing long distance telephony and television broadcasting. The involvement of satellites in IP networks is a direct result of new trends in global telecommunications where the Internet traffic will hold a dominant share in the total network traffic and special features of high‐capacity satellite channels to be discussed in this chapter. The large geographical coverage of the satellite footprint and its unique broadcasting capabilities as well as its high‐capacity channels keep the satellite as an irreplaceable part of communications systems, despite the high cost and long development and launching cycle of a satellite system. In this chapter, the role of satellites in future wireless Internet networks will be discussed and relevant research issues will be explored.
Cable Modems
Authors: McMullin Donald G. 
Published: November 2003

Abstract
Examined in this article are the critical requirements for high speed digital modem applications in a Hybrid Fiber Coax (HFC) environment. An overview of the basic elements and modulation formats of the system including the RF (Radio Frequency) tuner, IF (Intermediate Frequency) amplifiers, and frequency allocations for 2‐way transmission on a single cable are presented. A brief introduction to the data protocols and layer architectures of the modern TCP/IP internet stack is given. Requirements for IMD (Inter‐Modulation Distortion) and NF (Noise Figure) in a digital QAM (Quadrature Amplitude Modulation) system are contrasted with the traditional analog NTSC (National Television Standards Committee) format, which the cable systems were initially designed to support. RF, IF and overall system requirements for downstream and upstream data paths are presented including detailed performance requirements for AFEs (Analog Front Ends), ADCs (Analog to Digital Converters) and DACs (Digital to Analog Converters).
Communication Satellite Onboard Processing
Authors: Bernstein Steven 
Published: November 2003

Abstract
The primary purpose of communication satellites is to receive signals from one or more sources and relay them to intended recipients. To accomplish this many communication satellites incorporate one or more “translating repeaters” or “transponders” which simply amplify and frequency‐translate a band of frequencies. However, digital circuit and signal processing technology has progressed to the point that it is feasible and advantageous to implement more powerful processing functions on‐board the satellite. On‐board processing can enable systems to: make more effective use of power and bandwidth; improve multiple access performance; reject interference; and provide richer interconnectivity. On‐board techniques include: beam switching; adaptive antennas; demodulation‐remodulation; access control; and packet switching. This article will discuss each of the techniques and give a number of system application examples.
Sequential Decoding of Convolutional Codes
Authors: Han Yunghsiang S. , Chen Po‐Ning 
Published: November 2003

AbstractThis article surveys many variants of sequential decoding in literature. Rather than introducing them chronologically, this article first presents the Algorithm A, a general sequential search algorithm. The stack algorithm and the Fano algorithm are then described in details. Next, trellis variants of sequential decoding, including the recently proposed maximum‐likelihood sequential decoding algorithm, are discussed. Additionally, decoding complexity and error performance of sequential decoding are investigated, followed by a discussion on the implementation of sequential decoding from various practical aspects. Moreover, classes of convolutional codes that are particularly appropriate for sequential decoding are outlined.
Neural Networks and Applications to Communications
Authors: Manolakos Elias S. 
Published: November 2003

AbstractNeural Networks are highly interconnected distributed information processing architectures that are built by connecting together many simple processing elements. They come in many different flavors but all share the ability tolearni.e. to adapt their structure to capture the process that generates information in their environment, and utilize the internally formed representation of that process topredict, orgeneralize, when presented with unseen novel patterns. In this article we first introduce the basics of neural networks by describing the structure of commonly used neuron processors, some popular network architectures and learning rules. Then we explain why neural network methods have been utilized so extensively in the field of communications by presenting typical snapshots of their use in a representative subset of communication applications. Our intention is to introduce the interested non‐expert reader to the subject matter and not to present a comprehensive survey of the very large related literature.
Low‐Bit‐Rate Speech Coding
Authors: Ramírez Miguel Arjona , Minami Mario 
Published: November 2003

AbstractThis article is focused on speech coding methods for achieving communication quality speech at bit rates of 4 kbit/s and lower. The speech coding techniques are based on an all‐pole model of the vocal tract which may be implemented in the time domain with appropriately selected excitation functions or else may be fit to a spectral analysis of the speech signal. Three main types of coders are described below. Code‐excited linear prediction (CELP) coders select their excitation from waveform codebooks using analysis‐by‐synthesis closed‐loop techniques, which need to be supplemented by speech classification and open‐loop parametric techniques for keeping up with quality at lower rates. The prototypical sinusoidal coder (SC) has a bank of oscillators for signal synthesis, driven by a model of the magnitude spectrum. However, phase regeneration is important in enhancing speech reconstruction at low rates. Waveform interpolation (WI) coders afford a wider time‐frequency footprint for the representation of the excitation, showing a good potential for achieving toll quality at bit rates below 4 kbit/s.
MEMSforRF/Wireless Applications
Authors: De Los Santos Héctor J. 
Published: November 2003

AbstractSince the mid‐1990s, the prospect of applying microelectromechanical systems (MEMS) technology in RF/wireless communications systems has received considerable attention. This is due to RF MEMS' potential to provide the high‐performance devices that will enable the sophisticated, yet portable, wireless appliances demanded by consumers. In this chapter we first provide a review of the global connectivity problem, and how it motivates these wireless appliances. Then, we present the fundamentals of RF MEMS fabrication technology, in particular, bulk and surface micromachining, together with a sample of the structures and performance of some of the most important passive devices and circuits, such as inductors, varactors, transmission lines, resonators, switches and phase shifters, it makes possible.
Orthogonal Transmultiplexers: A Time‐Frequency Perspective
Authors: Akansu Ali N. , Sencar Husrev T. 
Published: November 2003

AbstractWe present a time‐frequency interpretation of orthogonal sets used in a transmultiplexer configuration that plays an important role in many single and multiuser communication systems in this article. It's shown that once independently treatedmulticarrier modulationtechniques like FDMA, TDMA and CDMA have their unified theoretical treatment usingorthogonal transformsand filter banks. This treatment helps one to build a multicarrier modulation based communication system using optimally designed orthogonal function set or signatures.
WDMMetropolitan‐Area Optical Networks
Authors: Tomkos Ioannis 
Published: November 2003

AbstractIn this article, the characteristics, requirements and architectures of optical metropolitan area networks are presented. The main features of system offerings proposed for metro networks are also discussed. We outline our considerations about the evolution of metro area networks from SONET rings, to transparent wavelength‐routed WDM rings. We also describe the major transport impairments that limit the performance of transparent WDM metropolitan area networks and we present the characteristics of metro‐optimized optical amplifiers, fibers and optical add/drop multiplexers. Finally, we discuss recent research results that demonstrate that a properly engineered system utilizing application‐optimized components and fiber will enable the buildup of cost‐effective metro‐optimized WDM all‐optical networks.
H
uffman Coding
Authors: Yang En‐hui , He Da‐ke 
Published: November 2003

Abstract
The past 25 years have witnessed widespread applications of Huffman coding. In this article, the theme of Huffman coding is thoroughly discussed. The concepts of uniquely decodable codes and prefix codes are reviewed. The Huffman coding problem is defined. The Huffman coding algorithm, the adaptive Huffman coding algorithm, Golomb codes, and Gallager‐Voorhis codes are described in detail. Their performance is analyzed theoretically. Applications of Huffman coding are also mentioned.