bluuebunny/crossref_metadata_2025 huggingface dataset:
Linear Antennas
Authors: Sandler Sheldon S.
Published: November 2003

The essential characteristics of linear antennas and associated devices are discussed both in qualitative and quantitative terms. Important topics include dipole, traveling wave, receiving, and pulsed antennas. Major sub‐topics covered are current distributions, radiation patterns, and circuit characteristics. Briefly covered is the important topic of linear antenna system design.
Image Processing
Authors: Bystrom Maja
Published: November 2003

Image processing can be loosely subdivided into a number of fields: acquisition, analysis, compression, reconstruction, watermarking and data hiding. Within the field of image acquisition, methods of image representation are discussed. The broad topic of filtering is presented as a tool for many of the processing techniques, and measures of image quality are given. Particular attention is paid to the common image transformations, the discrete cosine transform and the discrete wavelet transform. Analysis and segmentation of images, that is, recognition of pertinent features or characteristics, and the division of an image based upon features are discussed. Finally, the field of watermarking and data hiding as a means of protecting ownership or transferring information is presented.
BCH
Codes—Nonbinary And Reed‐Solomon*
Authors: Michelson Arnold M. , Levesque Allen H.
Published: November 2003

The description of nonbinary BCH codes closely follows the presentation for binary BCH codes in the preceding article. Nonbinary BCH codes are described as cyclic codes whose generator polynomials have particular sequences of roots. Reed Solomon codes are defined as nonbinary BCH codes whose symbol and locator fields are the same. Efficient encoding and decoding algorithms are described for hard‐decision and errors‐and‐erasures decoding. More general soft‐decision decoding schemes are discussed.
Cyclic Codes
Authors: Wicker Stephen B.
Published: November 2003

Cyclic codes are a class of highly structured algebraic block error control codes. We begin with an historical overview of the various subclasses of cyclic codes. We then provide a brief overview of the general theory of cyclic codes, and then turn to the three important classes (the Golay codes, BCH, and Reed‐Solomon codes). The article concludes with a discussion of several important applications.
Finite‐Geometry Codes
Authors: Fossorier M.
Published: November 2003

In this article, the constructions of linear block codes based on finite geometries are introduced. These finite geometry codes are related to another class of codes, namely low density parity check (LDPC) codes. The decoding of finite geometry codes exploiting the structure of finite geometries as well as methods developed for LDPC codes is then described.
Kasami Sequences
Authors: Kasami Tadao , Kohno Ryuji
Published: November 2003

After reviewing the basic concept of binary sequences, Kasami sequences are introduced and compared with Gold, Gold‐like and Dual‐BCH sequences. The relation between the design of binary sequences and the weight structure of binary cyclic codes is also examined.
Speech Perception
Authors: Müsch Hannes , Buus Søren
Published: November 2003

Speech is probably one of the oldest methods of communication. A large amount of research reveals a multitude of factors that are important for speech intelligibility. This article presents these factors, especially those that are important for the design of communication systems. A brief description of the speech signal is followed by a brief discussion of some basic properties of speech perception and an overview of some theories that have been proposed to account for them.
Hadamard Matrices and Codes
Authors: Bossert Martin
Published: November 2003

Hadamard matrices were born as a theoretical topic in combinatorics and have found various applications in different fields. In this article we present the definition and two possible constructions of Hadamard matrices, namely, the Sylvester and the Payley constructions. Next, we describe the connections to coding theory and then derive the fast Hadamard transform for signal processing. Finally, we comment on several applications.
Simulation of Communication Systems
Authors: Shanmugan K. Sam
Published: November 2003

Simulation plays an important role in the design, analysis, and implementation of communication systems. During the design of complex communication systems it is often infeasible to conduct performance analysis and design tradeoff studies using closed‐form mathematical formula techniques. Quite frequently, simulation is the only tool available for addressing important issues in the design, analysis, and implementation of communication systems. Simulation can be used to verify the functionality of communication systems, evaluate the performance of proposed systems, and generate specifications to guide their design. Since the early 1980s a variety of modeling and simulation techniques and tools have been developed and used to support the design and implementation of a broad range of communication systems and products ranging from multi‐million‐dollar communication satellites to handsets for the next generation of personal communication systems. This article presents an overview of the fundamental principles behind modeling and simulation of communication systems.
Time Division Multiple Access (
TDMA
)
Authors: Jung Peter
Published: November 2003

In this communication, a concise overview of TDMA (time division multiple access) and its application to mobile communications shall be presented. It shall be motivated that TDMA, being a means of medium access control (MAC), facilitates both a high spectral capacity and a reasonably low implementation complexity. Finally, a further evolution of TDMA based systems toward the combination with CDMA (code division multiple access) will be illustrated. This combination became part of UMTS (universal mobile telecommunication system), known as UTRA TDD (UMTS terrestrial radio access time domain duplex) or TD/CDMA.
Space–Time Codes for Wireless Communications
Authors: Al‐Dhahir Naofal , Calderbank A. R. , F. Naguib Ayman
Published: November 2003

Space‐Time Coding is a new coding/signal processing framework for wireless communications systems with multiple transmit/receive antennas. This new framework offers the best tradeoff between spectral efficiency and power consumption by optimum combination of modulation, coding, and diversity gains over flat‐fading channels.

Space‐time trellis codes offer the maximum possible diversity and coding gains without any sacrifice in transmission bandwidth. Their decoding requires a vector Viterbi algorithm. Alamouti‐type Space‐time block codes offer maximum diversity gain, much lower decoding complexity, and full rate transmission but sacrifice coding gain. The first part of this article reviews the fundamentals of space‐time coding for frequency‐flat fading channels.

For frequency‐selective fading channels, we describe, in the second part of the article, several competitive joint equalization and decoding schemes for space‐time codes that further exploit the temporal diversity of the channel. Channel estimation issues are also discussed. Exploiting the rich structure of space‐time codes is critical in simplifying the channel estimation, equalization, and decoding schemes.
Speech Processing
Authors: O'Shaughnessy Douglas
Published: November 2003

Synthetic speech conveys information to listeners in a convenient verbal way. It uses a computer program and stored portions of speech to formulate the synthetic voice. Its naturalness depends on the vocabulary of words to speak, the size of the stored speech, and the complexity of the synthesis programs. Simple voice response just plays back short copies of human speech signals, stored using digital sampling technology. More powerful systems can transform any text into comprehensible speech for various languages. So far such speech is usually intelligible, but often sounds less natural than human speech.
Code‐Division Multiple Access
Authors: Vojčić Branimir R. , Pickholtz Raymond L.
Published: November 2003

In this article basic principles of direct sequence spread spectrum for code division multiple access (CDMA) are described. CDMA is evolving into dominant multiple access technology for commercial wireless communications. Performance of conventional detection in CDMA is discussed, as well as the impact of imperfect power control. Several multiuser detection schemes that could improve the performance and enable robust operation in the presence of power control error are reviewed.
Continuous‐Phase‐Coded Modulation
Authors: Sundberg Carl‐Erik W. , Anderson John B.
Published: November 2003

Continuous Phase Modulation (CPM) is a class of constant amplitude digital modulation schemes which has both good power and band width efficiency. Memory is introduced in the signal by means of a continuous phase. This principle results in smooth power spectra with low spectral sidelobes. The continuous phase can also be exploited in detection over multiple digital symbols yielding lower bit error probability. Increased memory can be obtained by so called partial response techniques and combinations with convolutional codes. In this paper we give a brief overview of performance of various CPM systems. Comparisons are made with minimum shift keying (MSK) and Gaussian minimum shift keying (GMSK) systems. We show the existence of considerably better CPM schemes than these two reference systems. Receiver and transmitter structures are also discussed.
Automatic Repeat Request
Authors: Fuja Thomas E.
Published: November 2003

This article describes automatic repeat request (ARQ), a technique for improving the reliability of digitally‐transmitted data through the re‐transmission of corrupt frames. It begins by describing the use of cyclic redundancy check (CRC) codes to detect the presence of errors in received data. It then describes three protocols through which the transmitter and receiver coordinate the re‐transmission procedure; those protocols are “Stop‐and‐Wait,” “Go‐Back‐N”, and “Selective Repeat.” These three re‐transmission strategies are briefly analyzed in terms of their efficiency (“throughput”) and reliability (“frame error rate”). Finally, hybrid ARQ schemes, which incorporate both re‐transmission (ARQ) and forward‐error control (FEC) techniques, are discussed.
WirelessATM
Authors: Passas Nikos , Merakos Lazaros
Published: November 2003

This paper discusses the challenges and proposals for combining wireless communications and Asynchronous Transfer Mode (ATM). ATM is considered the most suitable transport technique for the Broadband Integrated Services Digital Network (B‐ISDN), due to its ability to flexibly support a wide range of services. On the other hand, wireless local area networks (LANs) are enjoying a large growth, providing increased transmission speed and reliable communication. The combination of wireless LANs and ATM aims at providing freedom of mobility with service advantages and quality‐of‐service guarantees. The paper studies two main areas of research in wireless ATM: i) advanced medium access control protocols, able to provide adequate support to ATM traffic classes, and ii) signaling enhancements for the support of mobility related operations, such as (de)registration, handover, location update, etc.
Threshold Decoding
Authors: Wu William W. , Massey James L.
Published: November 2003

A fairly comprehensive review is given of threshold decoding from its inception in the 1960s to the present time. Both forms of threshold decoding, namely majority decoding and APP decoding, are based on orthogonal parity checks. The construction of linear block codes and convolutional codes for threshold decoding is treated. The connection between self‐orthogonal codes and perfect difference sets is explained. Examples are used copiously throughout.
Speech Recognition
Authors: Billa Jayadev
Published: November 2003

The ease at which humans use speech understates the complexity of speech recognition for machines. The fundamental difficulty with speech recognition is the overwhelming variation in the production of speech. An automatic speech recognition system must successfully address this variability in speech before any useful output can be provided to the user. Typical automatic speech recognition systems use sophisticated mathematical models, Hidden Markov Models, to build a catalogue of speech features. These models, along with models of language grammar and structure, are used to recognize an incoming speech signal into its most likely word sequence.

Today, speech recognition systems are increasing deployed in areas where automation provides both convenience and cost savings. Key problems such as the ability to recognize speech in a variety of environments and over different speaking styles prevent the widespread use of speech recognition technology. In the future, solutions to these problems and others will pave the path for many new and exciting uses and applications of speech recognition.
Minimum‐Shift‐Keying
Authors: Simon Marvin K.
Published: November 2003

Among the many bandwidth efficient constant envelope modulation schemes that fall in the class of continuous phase frequency modulations, minimum‐shift‐keying is undoubtedly the most popular of the group that transmit binary information. The reason for this stems perhaps from the fact that MSK can be viewed both from the standpoint of frequency modulation and pulse‐shaped offset quadrature phase‐shift‐keying thereby allowing a large degree of flexibility in the design of transmitter and receiver implementations. In this chapter we explore a large variety of these implementation options with emphasis on their analytical characterization as well as their power and bandwidth performance behaviors. While the chapter attempts to cover a large body of the published literature on MSK, it is not offered to the readership as an all‐inclusive treatise on the subject but rather one that highlights the key technical contributions that are essential to a basic understanding of the modulation method as well as its associated demodulation, detection, and synchronization techniques.
Linear Predictive Coding
Authors: El‐Jaroudi Amro
Published: November 2003

Most real‐world signals carry redundant information from one sample (or snapshot) to the next. The focus of this article is on the use of LP in redundancy removal or data compression for coding applications (also known as linear predictive coding (LPC)). The remainder of the article is organized as follows: LP is formulated and the optimal prediction parameters are derived; the computational aspects and algorithms for the implementation of LP are explored; examples and applications of LPC are presented, and finally, variations on LPC used for coding speech signals are discussed.
Speech Coding: Fundamentals and Applications
Authors: Hasegawa‐Johnson Mark , Alwan Abeer
Published: November 2003

In this chapter, we present an overview of the most widely used algorithms, standards, and applications of wideband and narrowband speech coding. Algorithms for speech coding are classified into four broad headings: (1) waveform coding techniques (including PCM, companded PCM, and DPCM), which are typically used for landline telephony, internet telephony, and secure military communications; (2) subband coding, including perceptually transparent multi‐rate and embedded coding which is mainly used for internet and digital audio applications; (3) linear predictive analysis by synthesis coding (LPC‐AS) algorithms, including multipulse LPC, CELP, SELP, VSELP, and low‐delay CELP, which are typically used for digital cellular and telephony; and (4) LPC vocoders, including advanced vocoder algorithms (e.g., MELP, MBE, and PWI) are used for applications such as secure telephony and satellite telephony. Applications in areas such as voiceover IP (VoIP) and digital cellular are emerging and require a speech coder to gracefully adapt to rapidly changing channel conditions—a need that is met by embedded and multirate speech coders associated with joint source‐channel coding algorithms. Measures of speech coder perceptual quality include subjective measures of intelligibility (DRT and DALT) and naturalness (MOS and DAM), as well as objective measures such as segmental SNR, Bark spectral distortion, PSQM, and PESQ. Speech coding standards are set by organizations including the ITU (for landline telephony), MPEG (for multimedia applications), ETSI (for European digital cellular), TIA (for U.S. digital cellular), and DDVPC (for United States military applications).
BCH
Codes—Binary*
Authors: Michelson Arnold M. , Levesque Allen H.
Published: November 2003

Binary BCH codes are described as a subclass of cyclic codes. The required mathematical background is presented first ‐ finite fields, extension fields, and certain properties of polynomials defined over finite fields. Cyclic codes are introduced using the notion of the generator polynomial and BCH codes are defined in terms of the roots of the generator polynomial. Encoding and decoding of binary BCH codes are discussed and algorithms for both hard‐ and soft‐decision decoding are considered.
Optical Couplers
Authors: Keiser Gerd
Published: November 2003

Optical couplers are used in wavelength division multiplexing (WDM) applications for combining and separating wavelength channels, tapping off power for monitoring purposes, or adding and dropping specific wavelengths at a particular point in an optical fiber communication link. Most optical couplers are passive devices in the sense that they do not need to be powered externally to perform their function on optical signals. Fundamentally, optical couplers connect three or more fibers to combine, split, or redirect light signals. The key optical coupler performance parameters include insertion loss, excess loss, and crosstalk between channels.
Survivable Optical Internet
Authors: Mouftah Hussein T. , Ho Pin‐Han
Published: November 2003

The optical fiber communications with the densewavelength division multiplexing(DWDM) technology have been well recognized as a solution to the ever‐increased bandwidth demand by the versatile multimedia applications foreseeable in the future. The issue ofsurvivability, on the other hand, plays a key role on whether the communication systems can meet the requirements for service continuity. This article is an introduction to the state‐of‐the‐art of theoptical Internetwith a special emphasis on the issue ofsurvivability. A general survey over the evolution of architectural design for protection, and the sketches of implementing restoration algorithms, are provided with detailed discussions and heuristic examples.
Optical Memories
Authors: Ruane Michael
Published: November 2003

An optical memory is any system that stores and retrieves digital information using optical methods. This article begins with a discussion of the general characteristics of available optical memories. We then present an overview of compact discs, DVD, and magnetooptic discs. Next, we discuss advanced disc memories and conclude with holographic optical memories.
Optical Sources
Authors: Buus Jens
Published: November 2003

This article describes the development and the start of the art of optical sources for use as transmitters in fiber optic based communication systems. The evolution of optical sources is described starting from basic laser physics, semiconductor properties, and the transmission characteristics of optical fibers. This includes LEDs and simple laser structures, fixed wavelength single frequency lasers, wavelength selective lasers and tunable lasers.
Optical Filters
Authors: Poladian Leon
Published: November 2003

Optical filters are devices that introduce a wavelength dependent change into the amplitude or phase of an optical signal. The perform many of the functions required in wavelength division multiplexed (WDM) networks: they manipulate, combine, change and reroute information based on the wavelength of light. The most important classes of optical filters are Fabry‐Perot and Mach‐Zehnder interferometers, bulk diffraction gratings, thin‐film stacks, arrayed waveguide grating routers and Bragg gratings. Wavelength selective filters are used as optical demultiplexers, add/drop filters, switches and narrow wavelength mirrors. Wavelength corrective filters are used as amplifier gain‐flattening filters and as dispersion compensators.
Communication System Traffic Engineering
Authors: Kakaes Apostolos K.
Published: November 2003

In order to investigate the traffic engineering problem we begin with a study of the arrival process statistics. We then analyze the most common models used in traffic engineering: the Erlang B model, followed by the Erlang C and the Poisson models. We elaborate on these three models, individually and collectively. Finally, we discuss the problem of random‐access.
Adaptive Equalizers
Authors: Wesołowski Krzysztof
Published: November 2003

The paper considers the problem of adaptive equalization. After introduction of the system model and explanation of the phenomenon of intersymbol interference observed on many communication channels, the equalizer structures and algorithms are classified. Then, linear equalizers are considered, concentrating on Zero‐Forcing (ZF), Mean Square Error (MSE) and Least Squares (LS) adaptation algorithms. Subsequently, the choice of a reference signal and fast linear equalizers using periodic test signals are described. Next, the symbol‐spaced equalizer with the fractionally‐spaced equalizer is compared, showing performance superiority of the latter. The operation of the decision feedback equalizer (DFE) is explained in the next section. Subsequently, more complicated than a DFE, non‐linear equalization structures are described such as those based on the Maximum a Posteriori Probability (MAP) symbol‐by‐symbol detection and the Maximum Likelihood (ML) sequence estimation. Equalizers for trellis‐coded signals are also considered. The last part of the paper is devoted to blind adaptive equalizers and their algorithms. The Bussgang algorithms, the algorithms using the second‐order statistics of the received signal and the probabilistic algorithms are shortly characterized.
Serially Concatenated Codes and Iterative Algorithms
Authors: Benedetto S. , Montorsi G.
Published: November 2003

A serially concatenated code with interleaver consists of the cascade of an
outer
encoder, an interleaver permuting the outer code word bits, and an
inner
encoder whose input words are the permuted outer code words. Decoding is performed by an iterative technique based on two soft‐input soft‐output algorithms tailored to the trellis of the outer and inner encoders. The iterative algorithm can be easily extended to other forms of concatenation, where one or both encoders are replaced with system modules with some form of memory performing different functions, like a modulator, a channel with intersymbol interference, a multiuser combiner. In this paper, we give upper bounds to the
average
maximum‐likelihood error probability of serially concatenated block and convolutional coding schemes. Then, we present design guidelines for the outer and inner encoders that maximize the
interleaver
gain and the asymptotic slope of the error probability curves, describe the iterative decoding algorithm, and, finally, propose extensions to different schemes.
Spatiotemporal Signal Processing in Wireless Communications
Authors: Hatzinakos Dimitrios , Pacheco Ryan A.
Published: November 2003

Spacetime diversity can significantly enhance the performance of wireless communication systems. In this chapter we highlight the potential benefits, requirements and limitations of such systems. In the first half we provide a general treatment of the spacetime signal processing scenario and spacetime diversity and coding frameworks based on block spacetime codes. In the second half, a semiblind signal processing approach is presented and integrated with spacetime diversity and coding to form a realistic scenario for detection and estimation. Our aim is to illustrate the basic priciples and to suggest a realistic approach for implementation of spacetime wireless transcievers.
Streaming Video
Authors: Cohen Robert A. , Radha Hayder
Published: November 2003

The streaming of video over networks has become an important technology as the uses of networks such as the Internet have expanded beyond the exchange of just text and picture‐based information. The purpose of this article is to give an overview of the basic elements and concepts used within a videostreaming system. After describing the concept of videostreaming, we review the components that make up the basic server/client architecture of a video streaming system. We then give details on how video data is prepared for streaming, which include some of the technologies used for compression, rate scalability, and packetization. Next, we cover network‐related aspects such as session control, buffer and delay issues, and congestion control. We end with a summary of the new challenges that are being addressed by researchers and developers of today's videostreaming solutions.
Intranets and Extranets
Authors: Pakštas Algirdas
Published: November 2003

Intranets and extranets are types of networks which are based on the internet protocols (TCP/IP, HTTP, etc.). Article describes features of these networks and compares them with intergroupware. Examples of extranet applications are given. Open application standards are described in more detail. Network security issues are considered and a role of security policy is emphasized. Various schemes of applying encryption are described. Special attention is devoted to the secure Virtual Private Networks (VPNs) and use of tunnels for eanbling VPNs. Cost issues related to running of the Web‐site and various methods of remote access (ISDN, mobile) are considered. Example of the estimate for the cost of down time is given. Intranet and extranet trends are presented.
Wirelessad hocNetworks
Authors: Haas Zygmunt J. , Deng Jing , Liang Ben , Papadimitratos Panagiotis , Sajama S.
Published: November 2003

A mobile ad hoc network is a relatively new term for an old technology ‐ a network that does not rely on pre‐existing infrastructure. Roots of this technology could be traced back to the early 1970s with the DARPA PRNet and the SURAN projects. The new twitch is the application of this technology in the non‐military communication environments. Additionally, the research community has also recently addressed some extended features of this technology, such as multicasting and security. Also numerous new solutions to the “old” problems of routing and medium access control have been proposed. This survey attempts to summarize the state‐of‐the‐art of the ad hoc networking technology in four areas: routing, medium access control, multicasting, and security. Where possible, comparison between the proposed protocols is also discussed.
Wireless Packet Data
Authors: Balachandran Krishna , Budka Kenneth , Luo Wei
Published: November 2003

Wireless packet data is defined as transfer of information over radio links that are shared dynamically by multiple users without dedicating wireless resources to individual users during periods of inactivity. In this article, we provide an overview of wireless packet data. Important system aspects, such as system architecture, protocol stacks, system requirements, performance metrics and technology methods are discussed.
LEOSatellite Networks
Authors: Henderson Thomas R.
Published: November 2003

In this article, we survey the main system parameters for multi‐satellite communications networks, highlighting features distinguished from those of geostationary satellites. We first describe various non‐geostationary orbits and popular multi‐satellite constellation designs at low‐Earth‐orbit (LEO). Next, we contrast the differing characteristics of geostationary and non‐geostationary satellite systems, including link performance, tracking and link handoff issues, spectrum and interference concerns, and intersatellite communications links. Finally, we focus on networking aspects of satellite constellations, discussing various circuit‐switching and packet‐switching network architectures that have been proposed in the research literature.
Serially Concatenated Continuous‐Phase Modulation with Iterative Decoding
Authors: Moqvist Pär , Aulin Tor
Published: November 2003

Serially concatenated continuous phase modulation (SCCPM), or coded and interleaved CPM, is examined. Like turbo codes, SCCPM allows for iterative decoding based ona posterioriprobability algorithms. The system is analyzed through an upper bound on the average bit error probability with maximum likelihood sequence detection, showing that SCCPM is capable of providing interleaver gain ‐ and thus turbo‐like performance ‐ if a proper mapping of the CPM symbols is used. Simulations indicate that firstly, the analysis gives a satisfactory view of system performance when equal outer codes are used, and secondly, that remarkably good performance can be obtained with some simple systems. For unequal outer codes, the convergence of the iterative decoder will also have a significant effect on performance. Finally, a bandwidth/performance comparison of some selected systems shows that SCCPM can achieve large gains compared to the best known coded CPM systems without interleaving.
IMT
‐2000 3
G
Mobile Systems
Authors: Cerboni Anne , Charles Jean‐Pierre , Ghandour Pierre , i Tresserres Josep Sole
Published: November 2003

IMT‐2000 mobile systems are designed to provide wireless communication services including moving pictures, graphics, sound, and data to people on all continents. While standardization work has made significant strides to achieve a high degree of universality, IMT‐2000 in fact covers a family of standards. This article discusses the relevant standards issues and their implications in different regions. The migration paths from existing mobile systems toward 3G systems are reviewed. The enhanced data rates offered by IMT‐2000 are expected to provide a broad range of mobile multimedia services on a multiple choice of terminals. These new facilities and applications are examined. IMT‐2000 radio access and core network architecture is addressed, as are the most salient economic implications of migration toward 3G, with emphasis on license costs and new business models. The authors conclude with a discussion of beyond 3G evolution, which involves not only an all‐IP core network, but also optimization of scarce spectral resources through cooperation among heterogeneous networks.
Turbo Trellis‐Coded Modulation (TTCM) Employing Parity Bit Puncturing and Parallel Concatenation
Authors: Robertson Patrick , Wörz Thomas
Published: November 2003

In this contribution we explain the principles of Turbo Trellis Coded Modulation (TTCM), a bandwidth efficient channel coding scheme that has an overall structure similar to binary Turbo codes but employs Trellis Coded Modulation (TCM) as component codes. The combination of Turbo codes with powerful bandwidth efficient component codes leads to a straightforward encoder structure and allows iterative decoding in analogy to the binary Turbo decoder. However, certain special conditions are to be met at the encoder, and the iterative decoder needs to be adapted to the decoding of the component TCM codes and to the puncturing used in the code construction. We present simulation results for TTCM schemes for 8‐PSK, 16‐QAM and 64‐QAM modulation schemes with varying overall bandwidth efficiencies. These results show that TTCM is very powerful yet of modest complexity since simple component codes are used. Because TTCM relies onpuncturedTCM component codes, search results based on the best minimal distance of these punctured component codes are also presented. In the Appendix we summarize the derivation of the symbol‐by‐symbol component decoder; the reader will also find implementation guidelines based on processing in the logarithmic domain as well as a number of online and traditional references.
Network Traffic Modeling
Authors: Devetsikiotis Michael , Fonseca Nelson L. S.
Published: November 2003

Telecommunication networks are built to carry “traffic” in the form of data being transmitted. Efforts in network design, control or management require decisions and optimization actions that in turn require traffic
models
. This is why the science and “art” of traffic modeling has been playing a crucial role in the area of communication network design and operation. Traffic modeling has an analytical aspect, whereby suitable stochastic models are devised, and attributed to different types of data sources and network types; and a computational aspect where actual parameter values are estimated from measured data.

In this article, the most common models used in network traffic modeling are presented and basic concepts on traffic characterization are provided. Models for individual traffic sources as well as for aggregates of sources are also introduced. Finally, a brief discussion on the state‐of‐the art and on future trends is presented.
DMT
Modulation
Authors: Schur Romed , Pfletschinger Stephan , Speidel Joachim
Published: November 2003

Due to the enormous growth of telecommunication services during the last decade, the need for a modulation technique that can transmit reliably high data rates with high band‐width efficiency arises. In this context, multicarrier modulation schemes have become very popular for wireless, mobile as well as fixed networks. A well known applications is digital subscriber line (DSL) communication over wired media using the discrete multitone (DMT) modulation scheme.

In this article we present the principles of DMT modulation. We start from the basics of analogue and digital transmission and consecutively develop the main concepts of DMT, as there are: the incorporation of the discrete Fourier transform (DFT) into the modulation scheme, the use of the guard interval to combat interference, the principle of the generalized Nyquist theorem for perfect reconstruction of the signal, the cost‐effective equalization and the adaptive bit‐loading scheme.
Synchronous Optical Network (
SONET
) and Synchronous Digital Hierarchy (
SDH
)
Authors: Freeman Roger
Published: November 2003

SONET and SDH are similar digital transport formats that were developed for the specific purpose of providing a reliable and versatile digital structure to take advantage of the higher bit rate capacity of optical fiber. The objective of this article is to provide an overview of these two standards and some of their challenging innovations that make them interesting, such as the payload pointer.
Transmission Control Protocol
Authors: Aweya James
Published: November 2003

Transmission control protocol (TCP) has become the most widely used transport‐layer protocol today. TCP provides a reliable transport service that is used by most Internet applications, including Telnet, file transfer, electronic mail, and Web page access via HTTP. An important component of TCP is the collection of algorithms used to perform congestion control and error recovery. This article describes the basic design and operation of TCP, particularly the main features that make TCP a reliable transport protocol.
Cell Planning in Wireless Networks
Authors: Rohrbacher Kai , Kehrbeck Jürgen , Wiesbeck Werner
Published: November 2003

Overview of planning and simulating strategies for wireless networks ‐ from the past to the future. Focus is laid on the most popular system technologies like GSM900, GSM1800, 2.5G network extensions GPRS/EDGE and the upcoming so‐called “3rdGeneration systems (3G)” of the IMT‐2000 frame work like UMTS‐FDD in Europe, UMTS‐TDD, CDMA2000, TD‐SCDMA. The authors will show examples and methodologies based on network technologies used in Europe and also discussing detailed aspects of network planning and optimization using state‐of‐the‐art RNP‐(Radio Network Planning) Tools.
Routing and Wavelength Assignment in Optical
WDM
Networks
Authors: Rouskas George N.
Published: November 2003

This article discusses the routing and wavelength assignment (RWA) problem in optical networks employing wavelength division multiplexing (WDM) technology. Two variants of the problem are studied: static RWA, whereby the traffic requirements are known in advance, and dynamic RWA in which connection requests arrive in some random fashion. Both point‐to‐point and multicast traffic demands are considered.
Modems
Authors: Bhagavathula Ravi , Kwon Hyuck
Published: November 2003

With the recent proliferation of data communication mechanisms involving personal computers (PCs), the selection of a specific communication protocol/method has become a non‐trivial task. The objective of the current article is to present the concepts and features of modems. Starting with the more commonly used dial‐up modem, the reader is gradually introduced to the other “advanced” modems like DSL and cable modems.
Wireless Communications System Design
Authors: Tellambura Chintha , Annamalai A.
Published: November 2003

The wireless communications industry has been experiencing phenomenal annual growth rates recently. This degree of growth reflects the tremendous demand for commercial untethered communications services such as paging, analog and digital cellular telephony, and emerging Personal Communications Services (PCS). This article examines multipath fading channels and analytical tools for wireless system design. These analytical techniques are suitable as the first step of the design process of communication systems. Several such techniques are illustrated via examples on diversity reception, outage analysis and trellis codes. Theoretical expressions are derived for parameters such as the average error rate, the average output signal‐to‐noise ratio and the outage probability. Results for selection combining and maximal‐ratio combining and equal gain combining are obtained.
Design and Analysis of aWDMClient/Server Network Architecture
Authors: Wen Wushao , Mukherjee Biswanath
Published: November 2003

In this article, we describe a novel wavelength‐division multiplexing (WDM) client/server network architecture which is a passive‐star‐coupler‐based, broadcast‐and‐select network. In this architecture, all down‐stream data traffic uses WDM data channels and all upstream requests, upstream control messages, and down‐stream control messages use an Ethernet channel (called the control channel). This architecture is broadcast and multicast capable. We describe a detailed point‐to‐point connection‐setup procedure for this architecture. An internetworking scheme of this system with other networks is also described. The system's performance is analyzed in terms of whether the control channel or the data channels are the bottleneck. We also analyze the request delay, the request's channel‐holding time, and the system throughput following the model description. The analysis shows that the control channel is not a bottleneck. When the user request rate is high, the server‐channel scheduler is the most important adjustable factor to reduce the user response time. An illustrative analysis of FCFS scheduling policy for the system is also provided.
Optical Switching Techniques in
WDM
Optical Networks
Authors: Yoo Myungsik , Qiao Chunming
Published: November 2003

Optical Networks provide potentially huge bandwidth and transparent communication service as well as cost‐effective and future‐proof networking solutions. While the optical networking technology keeps evolving, it is important to re‐evaluate the optical switching techniques available today. In this article, we discuss three optical switching paradigms: wavelength routing, optical burst switching and optical packet switching. As an interim solution for optical networks, the optical burst switching technique is shown to be the most suitable.
Wavelength‐Division Multiplexing Optical Networks
Authors: Modiano Eytan
Published: November 2003

This article provides an introduction to wavelength‐division multiplexing (WDM) networks, with the objective of introducing the reader to the current state of the art. We begin with an overview of WDM network technology and proceed to discuss WDM network architectures. First, we give an overview of WDM‐based local area networks that are usually based on a broadcast star topology. We proceed to consider WDM wide area networks and discuss critical issues in their design such as wavelength assignment, wavelength conversion and joint design of optical and electronic networks. While we attempt to provide a good overview of the field, this article is by no means comprehensive. Our hope is that we provide the reader with a sufficient introduction to pursue the subject in more detail.
Turbo Equalization
Authors: Narayanan Krishna R.
Published: November 2003

Turbo equalization is an iterative technique to perform joint equalization and decoding when channel coding is employed for communicating though an ISI channel. The idea is to exchange soft extrinsic information between a soft‐input soft‐output (SISO) decoder and an SISO equalizer in an iterative fashion. This chapter presents the basic concepts behind turbo equalization and summarizes some the main developments in this area. First, trellis based SISO equalization and interference cancellation based SISO equalization are explained. Then, techniques to analyze the performance of turbo equalization are discussed. The analysis techniques include distance spectrum based analysis and extrinsic information transfer diagram based analysis.
General Packet Radio Service (GPRS)
Authors: Bettstetter Christian , Hartmann Christian
Published: November 2003

The General Packet Radio Service (GPRS) is a data bearer service for GSM and IS–136 cellular networks. Its packet–oriented radio transmission technology enables efficient and simplified wireless access to Internet protocol–based networks and services.

After an explanation of the fundamental features of GPRS, this article describes the network components, services, protocols (e.g. session and mobility management), packet routing, air interface (channels, multiple access, channel coding), and security aspects.
ATMSwitching
Authors: Chen Thomas M. , Liu Stephen S.
Published: November 2003

ATM switches are high‐speed packet switches designed to process and forward ATM cells. The functional components of a general ATM switch architecture are described. The switch fabric provides the central function of cell forwarding. The switch fabric design involves trade‐offs between various approaches and a choice of input or output buffering. In addition to cell forwarding, ATM switches require capabilities for connection admission control, traffic control, and OAM (operations and maintenance).
Local Area Networks
Authors: Carson John H.
Published: November 2003

Local‐area networks (LANs) had their beginning at Xerox PARC in 1976 with the development of the Ethernet system. As Ethernet was being embraced by industry, the IEEE formed the 802 committee to standardize LAN (and later MAN) technology. The first mass‐produced Ethernet systems operated with a data rate of 10 Mbps (million bits per second). Today standards and products exist for 100 and 1000 Mbps data rates with 10 Gbps in the final stages of standardization and 40 Gbps as the next target. Wireless Ethernet is also readily available. Although originally targeted to short distances, varieties of Ethernet have been developed for longer point‐to‐point, full‐duplex connections that are competing with long‐established technologies such as SONET and ATM. Finally, the use of Ethernet to the home is being addressed—the “Ethernet in the first mile” activity. Thus Ethernet is becoming ubiquitous for all varieties of networking.
Image and Video Coding
Authors: Li Shipeng , Li Weiping
Published: November 2003

Image and video coding is a research topic with a rich history and enormous amount of publications. This article provides an overview of some basic concepts, principles, techniques, and standards in this research area.
WirelessIPTelephony
Authors: Famolari David R.
Published: November 2003

Both the Internet and wireless telephony have created unprecedented operating freedoms that are forcing paradigm shifts in business and social communication practices. Their impact, however, has emerged from opposite design philosophies. The wireless telephone network was designed to provide mobile access to speech applications; the Internet, on the other hand, was designed to deliver a wide variety of application types to fixed locations. The freedom and mobility offered by wireless networks provides a perfect compliment to the economies of scale and flexibility offered by the IP‐based Internet. As IP becomes an important driver of both core and access networks, it must support wireless voice at comparable levels of spectrum efficiency and voice quality as cellular telephony. Similarly, wireless network practices must be modified to accommodate IP‐based packet protocols. It is our aim here to describe the design challenges and technical hurdles facing successful deployment of wireless IP telephony.
Interference Suppression in Spread‐Spectrum Communication Systems
Authors: Amin Moeness G. , Zhang Yimin
Published: November 2003

This chapter discusses interference excision techniques in spread spectrum communications systems. Both stationary and nonstationary interferers are considered. Sinusoidal, autoregressive, digital communication, and polynomial phase interference signals are effectively suppressed by different excision methods; each is suitable for one or more types of interferers. Time‐, frequency‐, and time‐frequency domain methods for analysis and estimation of the interference parameters are summarized. Domains other than time and frequency, such as the Gabor‐domain, the Wavelet‐domain, and quadratic time‐frequency signal representations, are appropriate for nontraditional smart jamming in which the interference parameters are highly dependent on time. Excision methods can be linear, bilinear, or nonlinear with performance dependent on the interference power relative to the desired signal and noise. In some cases, the slight performance enhancement offered by bilinear and nonlinear methods may not properly justify the increase in the algorithm complexity. The BER and receiver SINR expressions and curves are presented in this chapter for some of the key interference excision techniques.
CDMA
/
IS
95
Authors: Sam Lee Jhong , Miller Leonard E.
Published: November 2003

This article describes the design of the IS‐95 (cdmaOne) second‐generation (2G) cellular telephone system, which uses Walsh‐function orthogonal multiplexing for channelization on the forward (base‐to‐mobile) link and spread‐spectrum code‐division multiple access (CDMA) on the reverse (mobile‐to‐base) link. The system's uses of time, space, and multipath diversity are explained, and initial approaches to a third‐generation (3 G) system design are summarized.
Propagation Models for Indoor Communications
Authors: Landstorfer F. , Woelfle G. , Hoppe R.
Published: November 2003

The performance of wireless communication systems depends in a fundamental way on the mobile radio channel. Inside buildings the transmission path between transmitter and receiver can vary from simple line‐of‐sight to one severely obstructed by walls and furniture. As a consequence predicting the propagation characteristics between two antennas still belongs to the most demanding tasks for the design and installation of wireless indoor communication systems, ranging from low bit‐rate cordless telephone and cellular systems to high bit‐rate wireless local area networks (WLANs). This article gives a survey on a variety of methods for modeling wave propagation in indoor scenarios.