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Wireless Communications

Cover Image Copyright Year: 2011
Author(s): Molisch, A.
Publisher: Wiley-IEEE Press
Content Type : Books & eBooks
Topics: Communication, Networking & Broadcasting
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Abstract

"Professor Andreas F. Molisch, renowned researcher and educator, has put together a comprehensive, clear, and authoritative book on wireless communications. The Second Edition, which includes a wealth of new material on important emerging topics, ensures the book will continue to be a key resource for every student, researcher, and practitioner in the field."Professor Moe Win, MIT, USA Wireless communications has grown rapidly over the past decade from a niche market into one of the most important, fast moving industries. Fully updated to incorporate the latest research and developments, Wireless Communications, Second Edition provides an authoritative overview of the principles and applications of mobile communication technology. The author provides an in-depth analysis of current treatment of the area, addressing both the traditional elements, such as Rayleigh fading, BER in flat fading channels, and equalization, and more recently emerging topics like multi-user detection in CDMA systems, MIMO systems, and cognitive radio. The dominant wireless standards, including cellular, cordless and wireless LANs, are discussed. • Topics featured include: wireless propagation channels, transceivers and signal processing, multiple access and advanced transceiver schemes, and standardized wireless systems. • Combines mathematical descriptions with intuitive explanations of the physical facts, enabling readers to acquire a deep understanding of the subject. • Includes new chapters on cognitive radio, cooperative communications and relaying, video coding, 3GPP Long Term Evolution, and WiMax; plus significant new sections on multi-user MIMO, 802.11n, and information theory. • Companion website featuring: solutions manual and presentation slides for instructo rs, appendices, list of abbreviations and other useful resources.  

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      Frontmatter

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.fmatter
      Page(s): i - xxxxxvi
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      The prelims comprise:
      Half-Title Page
      Title Page
      Copyright Page
      Table of Contents
      Preface and Acknowledgements to the Second Edition
      Preface to the First Edition
      Acknowledgments to the First Edition
      Abbreviations
      Symbols View full abstract»

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      Part Introduction

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.part1
      Page(s): 1
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

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      Applications and Requirements of Wireless Services

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch1
      Page(s): 3 - 25
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter provides an overview of the different services and applications of wireless communications, and their impact on technical requirements. It starts out with a brief history of the development of wireless communications, from the first public radio and TV broadcasting, to satellite communications, to the great boom of cellular voice communications in the 1990s, to the current focus on mobile data transmission and sensor networks. Next, we discuss the characteristics of the main types of services: broadcast, paging, cellular telephony, trunking radio, cordless telephony, wireless local area networks and personal area networks, fixed wireless access, ad-hoc networks and sensor networks, and satellite communications. For each of those categories we describe the requirements for data rate, range and number of users, whether communication is unidirectional or bi-directional, ability to handle mobility, energy consumption, use of spectrum, and quality of service. A discussion of the economic and social aspects of wireless communications concludes the chapter. View full abstract»

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      Technical Challenges of Wireless Communications

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch2
      Page(s): 27 - 36
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter describes the basic technical challenges for wireless communications systems, and discusses the difference to the challenges encountered in wired communications. The first big challenge is multipath propagation, i.e., the existence of multiple signal copies arriving at the receiver. Multipath propagation in turn leads to fading and intersymbol interference. A further challenge is the limited amount of spectrum available for wireless communications; the chapter briefly discusses the most important frequency bands assigned to various wireless services, and the difference between regulated and unregulated spectrum. A brief discussion of the challenges of limited energy available at mobile stations, and of the impact of mobility, concludes the chapter. View full abstract»

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      Noise and InterferenceLimited Systems

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch3
      Page(s): 37 - 44
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter reviews the basics of noise and interference, and discusses link budgets for wireless links. We start out by a review of the different noise sources, namely thermal noise, man-made noise, and receiver noise, and show how to compute the noise figure of a cascade of components. We then demonstrate how to set up a link budget for noise-limited systems, as well as for interference-limited systems. The result of a link budget is either the necessary transmit power, or the maximum range that a transmitter can support with a given power. View full abstract»

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      Part Introduction

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.part2
      Page(s): 45 - 46
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

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      Propagation Mechanisms

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch4
      Page(s): 47 - 67
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter gives an overview of the basic physical processes determining the propagation of wireless signals. We start out with free-space propagation, reviewing the concepts of effective antenna area, free-space pathloss, and Friis' law. We then turn to the reflection from, and transmission into, dielectric or conducting materials: Snell¿s law gives the appropriate transmission and reflection coefficients for different polarizations, namely TE and TM waves. From insights gathered here, we then compute the pathloss law that holds when both line-of-sight and ground reflection is present. We next turn to the process of wave diffraction, first describing the diffraction by a single screen that can be quantified in terms of the Fresnel integral, and interpreted by means of Fresnel zones. We then describe different approximation methods for computing the diffraction by multiple screens: Bullington method, Deygout method, and Epstein-Petersen method. We next turn to the diffuse scattering of radiation on rough surfaces, which can be described by the Kirchhoff method or the (more accurate, but also more complicated) perturbation method. A discussion of waveguiding in corridors and street canyons concludes the chapter. View full abstract»

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      Statistical Description of the Wireless Channel

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch5
      Page(s): 69 - 99
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter deals with the statistical description of multipath channels in the narrowband case. A deterministic two-path model serves to introduce the concepts of constructive and destructive interference (superposition) of waves. From a computer simulation, we then see how the superposition of multiple waves leads to more ¿random-looking¿ distributions of the fieldstrength. The distribution of the fieldstrength can be shown, by means of the central limit theorem, to become zero-mean complex Gaussian. The corresponding distribution of the absolute amplitude is a Rayleigh distribution ¿ its properties are reviewed here. We then proceed to the case when a dominant multipath component, e.g., a line of sight component (LOS), is present in addition to many weaker components. In this case, the amplitude distribution is a Rice distribution; for some cases also a Nakagami distribution is found to be valid. For all those distributions we show how to compute the fading margin required in link budgets. Next we discuss the temporal variations of the propagation channel: movement of transmitter, receiver, or interacting objects (scatterers) leads to temporal variations. The Doppler spectrum is introduced as a measure for the frequency dispersion (spread) of a sinusoidal transmit signal and shown to be related to the temporal correlation function of the received signal. The Jakes spectrum (also known as Clarke spectrum) is the most widely used shape. We then compute the average duration of fades, the level crossing rate, and the statistical properties of the random frequency modulation (random FM) in Rayleigh-fading channels. The next topic is the fading variations due to shadowing, which usually follow a lognormal distribution. The combination of Rayleigh and lognormal distribution leads to the Suzuki distribution. View full abstract»

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      Wideband and Directional Channel Characterization

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch6
      Page(s): 101 - 123
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter discusses the wideband characterization of wireless channels, in other words, the delay dispersion (sometimes also called temporal dispersion), which is equivalent to frequency selectivity. We set up the system-theoretic description of propagation channels with both temporal variations and delay dispersion as linear time-variant systems. Time-variant impulse response, Zadehï¿¿ï¿¿ï¿¿s time-variant transfer function, Doppler-variant impulse response (spreading function), and Doppler-variant transfer function are shown to be equivalent deterministic descriptions. Stochastic descriptions of the second-order statistics of LTV systems lead to correlation functions that depend on four variables; by introducing the wide-sense stationary uncorrelated scattering (WSSUS) assumption, the description is simplified to functions of two variables: delay cross power spectral density, time-frequency correlation function, and scattering function. Condensed descriptions (integrals or moments) of these quantities include the power delay profile, the rms delay spread, the maximum excess delay, the delay window, the interference quotient, coherence bandwidth, rms Doppler spread, and coherence time; they are defined and their interrelation is discussed. We then briefly describe the peculiarities of ultra-wideband (UWB) propagation channels. We then describe angular properties of wireless propagation: the double-directional impulse response describes direction of departure (DoD, also known as angle of departure, AoD) and direction of arrival (DoA, or angle of arrival AoA) of the multipath components. Corresponding stochastic descriptions include the double-directional delay power spectrum, from which the angular delay power spectrum (ADPS), angular power spectrum (APS), and angular spread can be derived. The section concludes by showing the relationship between the transfer funct ion matrix common in MIMO systems, and the double-directional impulse response. View full abstract»

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      Channel Models

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch7
      Page(s): 125 - 143
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter reviews the most common models for wireless propagation channels. For the prediction of the pathloss, the Okomura-Hata model, the COST-231 Hata model, and the Walfish-Ikegami model are commonly used for outdoor environments, while the Motley-Keenan model is used for indoor. For the delay dispersion, tapped delay line models are commonly used. The COST 207 models (also known as GSM models) were introduced in the 1980s; later the ITU models were used in the context of third-generation cellular systems. The Saleh-Valenzuela model is particularly popular for indoor environments. More recent models that describe also angular dispersion are the COST 259 Directional Channel Model, the 3GPP SCM (spatial channel model), the IEEE 802.11n channel model, and the Winner model (also known as ITU IMT-Advanced model); the IEEE 802.15.4a model is intended for ultra-wideband channels. All those models are described in the chapter. We furthermore discuss alternative generic modeling methods, including geometry-based stochastic channel models (GSCM) and deterministic models such as ray tracing and ray launching. View full abstract»

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      Channel Sounding

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch8
      Page(s): 145 - 164
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter describes channel sounding, i.e., the measurement of the characteristics of propagation channels. It starts with a basic discussion of the identifiability of channels ¿ generally channels can be only identified uniquely if they are underspread. Time-domain measurements can be performed by impulse sounders or correlative channel sounders (including the swept time domain cross correlator); the chapter also discusses synchronization between transmitter and receiver, as well as averaging to increase the signal-to-noise ratio. Frequency-domain measurements can be performed with vector network analyzers; chirp sounders are also an attractive alternative. The chapter next describes how to perform directionally resolved measurements, i.e., determine directions of arrival. A data model for signals arriving at an antenna array is established; both beamforming strategies, and high-resolution algorithms (especially Capon¿s beamformer or minimum-variance method, and the ESPRIT algorithm are discussed. We also describe different directional sounder concepts, based on real arrays, virtual arrays, or switched arrays. The generalization of these concepts to MIMO or double-directional sounding concludes this chapter. View full abstract»

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      Antennas

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch9
      Page(s): 165 - 178
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter gives an overview of antenna characteristics, and describes the types of antennas most relevant for wireless communications. It starts out by reviewing the key characteristics of antennas, namely antenna gain, directivity, efficiency, mean effective gain, bandwidth, and quality (Q-factor). Antenna matching and its physical limits (Fano bound) are also discussed. We then move to the description of the most common types of antennas, including dipole antennas, helix antennas, patch antennas, and planar inverted F (PIFA) antennas. We then discuss antenna arrays, in particular the array pattern and array gain, and describe the use of arrays at cellular base stations. A discussion of pattern distortions by objects near antennas concludes the chapter. View full abstract»

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      Part Introduction

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.part3
      Page(s): 179 - 180
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

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      Structure of a Wireless Communication Link

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch10
      Page(s): 181 - 186
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter gives a very brief overview of the structure of wireless transmitters and receivers. The key components, including baseband processing elements (encoders/decoders, modulators) as well as RF components (including analog-to-digital and digital-to-analog converters, mixers, filters) are discussed, and their place in the transceiver chains are explained. View full abstract»

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      Modulation Formats

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch11
      Page(s): 187 - 219
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter describes (i) the fundamentals of digital modulation, (ii) the modulation formats that are most popular for wireless communications. We start out with the generic forms of pulse amplitude modulation (PAM) and multi-pulse modulation (including continuous-phase modulation). The effects of the shape of basis pulses (including Nyquist pulses for PAM and Gaussian-filtered phase-pulses) on the intersymbol interference and spectral efficiency are described. We then discuss the power spectrum of PAM and show that it is (under certain conditions) identical to the power spectrum of the basis pulses. Finally, we introduce the signal space diagram, the most important representation of digital modulation, where each element of the modulation alphabet is represented by a point in a low-dimensional space, and the Euclidean distance between the points is an important parameter for the noise-sensitivity of the modulation format. Suitable choice of expansion functions (basis functions) and the Gram-Schmidt orthogonalization procedure are also described. After these general descriptions, we turn to the specific popular modulation formats, for each of which we describe their bandpass and lowpass (complex baseband) description, their representation in the signal space diagram, power spectrum, and discuss the impact of choice of basis pulses. In particular, we discuss binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), also known as quadrature amplitude shift keying (QAM), pi/4 differential phase shift keying (pi/4 DQPSK), offset quadrature phase shift keying (OQPSK), higher-order PSK and QAM, binary frequency shift keying (BPSK), Minimum Shift Keying (MSK) and other forms of continuous phase frequency shift keying (CPFSK) such as Gaussian MSK (GMSK), and finally pulse position modulation (PPM). View full abstract»

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      Demodulation

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch12
      Page(s): 221 - 248
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      We discuss the demodulation of digital signals, and the bit error rate due to noise, fading, delay dispersion and frequency dispersion. We first derive the structure of optimum receivers (maximum a posteriori, MAP and maximum likelihood, ML) in additive white Gaussian noise (AWGN) for coherent reception. The signal-space diagram allows a unified representation of various modulation formats, and - exploiting Wozencraftï¿¿ï¿¿ï¿¿s irrelevance theorem ï¿¿ï¿¿ï¿¿ enables computation of pairwise error probabilities based on the Euclidean distance between transmit and receive signal constellation points. For modulation alphabets with multiple (more than two) elements, the union bound can be used to approximate the total symbol error probability. We then also derive the optimum receiver structure for noncoherent reception, and provide the error probability for this type of reception as well as for differential detection. The chapter then turns to two methods of computation of the bit error probability (BER) and symbol error probability (SER) in flat-fading channels: the first one averages the BER of an AWGN channel over the distribution of the signal-to-noise ratio (SNR). The latter uses an alternative representation of the Q-function to express the BER in terms of the moment generating function (MGF) of the fading distribution. In Rayleigh fading, the SER decreases linearly with increasing SNR, while in Rician fading, a faster decay can be observed. We also discuss the difference between BER and outage probability. Finally, the chapter analyzes the SER due to delay dispersion and frequency dispersion, which is often called error floors. Spikes in the group delay can be interpreted as leading to the increased errors. The impact of the shape of the power delay profile, sampling time, and filtering, is also discussed. A very general method for the analysis of SERs in channels su ffering from both AWGN and dispersion, based on quadratic forms of Gaussian random variables, is also described. View full abstract»

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      Diversity

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch13
      Page(s): 249 - 275
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter discusses diversity. After defining the correlation coefficient between signals, we describe the various types of microdiversity (for combatting small-scale fading): spatial diversity, temporal diversity (or, equivalently, Doppler diversity), frequency diversity (delay diversity), angular diversity (pattern diversity), and polarization diversity. For spatial diversity, the correlation coefficient as a function of angular power spectrum of the signal and antenna spacing is derived. Temporal and frequency diversity needs to be combined with (interleaved) coding or selective retransmission (automatic repeat request, ARQ). Angular diversity can profit from mutual coupling. For large-scale fading, macrodiversity needs to be employed. We then turn to the methods for exploiting the multiple signals. In selection diversity, the ï¿¿ï¿¿ï¿¿bestï¿¿ï¿¿ï¿¿ signal (either the one with the highest field strength ï¿¿ï¿¿ï¿¿ RSSI-driven diversity, or the lowest BER ï¿¿ï¿¿ï¿¿ BER-driven diversity) is used, while all other signals are discarded. In combining diversity, the signals from the different diversity branches are linearly weighted and added. Various types of weights lead to different solutions: maximum ratio combining MRC, equal gain combining EGC, and optimum combining (MMSE combining). Hybrid selection maximum ratio combining provides a compromise between selection diversity and combining diversity. The chapter finally describes methods for the computation of the symbol error probability (SER) and bit error probability (BER) of the various combining methods in noisy fading channels. Diversity is also suitable for reducing the SER caused by delay dispersion and frequency dispersion. A discussion of transmit diversity, with channel state information (maximum ratio transmission, MRT) and without channel state information (including delay diversity and phase-sweeping d iversity) concludes the chapter. View full abstract»

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      Channel Coding and Information Theory

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch14
      Page(s): 277 - 317
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter discusses fundamentals of information theory and channel coding (error correction coding ECC, Forward error correction FEC). First, key results of Shannon, including channel capacity and the relationship between transmit power and bandwidth, are discussed. Block codes multiply a block of data with an encoding matrix. For systematic codes, the resulting codeword consists of systematic bits and parity check bits. Decoding is achieved by multiplication with a parity check matrix and determination of the syndrome vector. Correction of errors within the correction sphere can be done, e.g., through lookup tables. Convolutional codes send the source data stream through shift registers and adders, a process described by a trellis diagram. Maximum-likelihood sequence estimation (Viterbi algorithm) determines the (transmit) bit sequence with best distance metric (Hamming or Euclidean) from the received signal. Methods for combining coding and higher-order modulation include trellis coded modulation (using set partitioning for code design) and bit-interleaved coded modulation (BICM). Turbo codes are close to capacity-achieving. They are based on transmitting differently interleaved convolutional codes; receivers use soft decoding of the constituent codes and iterative exchange of soft information (log-likelihood ratios). Low-density parity check codes (LDPCC) are decoded by belief propagation (message passing), where variable nodes and constraint nodes exchange beliefs about the codeword. In fading channels, (block or convolutional) interleaving is essential to provide diversity. From an information-theoretic point of view, in fading channels we can distinguish between the ergodic capacity and the outage capacity. If the channel state information is known at the transmitter, waterfilling is the optimum power allocation strategy. Automatic Repeat Request ARQ) and Hyb rid ARQ (including chase combining or incremental redundancy) are described in the appendix. View full abstract»

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      Speech Coding

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch15
      Page(s): 319 - 342
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter analyzes how speech is encoded for transmission via digital wireless connections. Speech coders can be generally classified as waveform coders and model-based coders (vocoders), as well as hybrid coders. To explain vocoders, we summarize the generation of speech in the vocal tract, which can be approximated by the source filter model (excitation generator followed by a time-variant filter). Next is speech perception, in particular auditory speech modeling, and perception quality measures like mean opinion score, two-way conversational tests, and the standardized Perceptual Evaluation of Speech Quality, PESQ. The chapter then discussed stochastic models for speech. A nonstationary stochastic model is clearly necessary. Woldï¿¿ï¿¿ï¿¿s decomposition allows representation as a sum of a regular and a singular component, and forms the basis of linear predictive vocoders, and harmonic+noise modeling. Once the signal model and the parameter estimation algorithms have been selected, the encoder has to quantize the parameters. Either scalar or vector quantization can be used in this context. Hybrid coders furthermore quantize the residual signal, and transmit it using a predictive signal model, for which perceptual noise-shaping filter can be used. Other discussed techniques include long-term prediction and analysis-by-synthesis. The chapter concludes by discussing practical aspects of vocoders. Unequal error protection can be used to particularly protect those bits that have the largest impact on speech quality. Adaptive multirate coding adapts the encoding rate to the rate that can be sustained by the current channel state. Voice activity detection can be used to transmit only when somebody is actually speaking, and thus improve spectral efficiency. Adaptive postfiltering, and joint echo and noise control, improve the perceived quality. Talker authentication and three-dimensional audio further enhance the user experience, and form part of an acoustic telepresence. View full abstract»

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      Equalizers

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch16
      Page(s): 343 - 361
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter discusses equalizers for single-carrier transmission in wireless systems. We first set up a time-discrete model for the channel, filters, and equalizer. A noise-whitening filter or precursor equalizer ensures white noise at the equalizer input. Transmit filter, channel, matched filter, and noise whitening filter can be modeled together by an equivalent time-discrete channel. We then turn to the various types of equalizers. Linear equalizers consist of linear filters, usually tapped delay lines (though IIR filters and lattice filters are also possible), whose coefficients are optimized according to certain criteria. Zero-forcing equalizers eliminate intersymbol interference, but lead to noise enhancement, while minimum mean square error (MMSE) equalizers trade off these error sources. Adaptation algorithms for the coefficients trade off complexity, convergence rate, and misadjustment. Example algorithms include the least mean square (LMS) algorithm (stochastic gradient method), the recursive least squares algorithm (RLS), or direct computation of the Wiener filter. Decision feedback equalizer (DFE) consist of a feedforward filters and a feedback filter that eliminates the postcursor impact. DFEs generally perform well, but must avoid error propagation. The best performance is obtained by maximum-likelihood sequence estimators (MLSE) or Viterbi equalizers. They act similar to Viterbi decoders for convolutional codes, since the channel can be interpreted as a rate-1 convolutional encoder. Finally, we discuss blind equalizers, which do not require a training sequence for detection. Certain signal properties, e.g., constant envelope, finite symbol alphabet, cyclostationarity, or spectral correlation, can be used to separate the effect of the channel on the received signal from the signal modulation, and perform implicit equalization. The best-known algorithms are the constant-modulus algorithm (CMA), blind MLSE, and algorithms using higher-order statistics. View full abstract»

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      Part Introduction

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.part4
      Page(s): 363 - 364
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

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      Multiple Access and the Cellular Principle

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch17
      Page(s): 365 - 385
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter discusses the simultaneous communication of multiple users. We start out by discussing multiple access between a single base station (access point) and multiple mobile stations (handsets, users). In particular, Time Division Multiple Access (TDMA) and Frequency Division Multiple Access (FDMA) allow a simple assignment of the resources to different users; Code Division Multiple Access (CDMA) is relegated to Chapter 18. Basic aspects of queuing theory, including the Erlang B and Erlang C model, are then introduced, and we show that due to the trunking gain, the admissible ratio of offered traffic to number of available channels increases (for a given outage probability) when the number of available channels increases. We then discuss various schemes for multiple access for packet radio, including Aloha, slotted Aloha, Carrier Sense Multiple Access (CSMA) and packet reservation multiple access. A brief discussion of routing in packet radio is also given, though a more extensive discussion is relegated to Chapter 22. Duplexing, in particular Frequency Division Duplexing (FDD) and Time Division Duplexing (TDD), allows the separation of transmitted and received data. We then describe the cellular principle. In order to increase the number of simultaneous links on which communication can take place, an area is divided into multiple cells, each of which has one base station. In order to limit interference, the same time-frequency resource can only be reused in cells separated by a certain minimum reuse distance; the number of cells that are all using disjoint time-frequency resources is called the cluster size. For the simple case of hexagonal cells, explicit equations for cluster size are given. Various methods for increasing capacity, including overlay structures, fractional loading, and partial frequency reuse, are also discussed. The information theory of bro adcast channels (downlink) and multiple-access channels (uplink) is also briefly described. View full abstract»

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      Spread Spectrum Systems

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch18
      Page(s): 387 - 416
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      In spread spectrum systems the transmit signal occupies a wider spectrum than required by the symbol rate. Slow and fast Frequency Hopping (FH) changes the carrier frequencies, and can be used for multiple access in synchronized and unsynchronized systems. In Code Division Multiple Access (CDMA), the data sequences are multiplied by spreading sequences with short chip duration, thus increasing the occupied bandwidth by the ï¿¿ï¿¿ï¿¿spreading factorï¿¿ï¿¿ï¿¿. Spreading sequences with suitable crosscorrelation (and autocorrelation) properties allow separation of users: pseudonoise (PN) sequences like maximum-length (m-) sequences, Gold-, and Kasami-sequences; Walsh-Hadamard codes and Orthogonal Variable Spreading Factor (OVSF) codes. In delay-dispersive channels, Rake receivers consisting of multiple correlators (fingers) collect the energy contained in different multipath components. Synchronization of the receivers to the available signals occurs in two steps: acquisition and tracking. CDMA allows universal frequency reuse (i.e., reuse distance one). Inter-user interference (consisting of intra-cell and inter-cell interference) is noise-like. Randomization of inter-cell interference is effected by multiplying the signals in different cells with different scrambling codes. Power control ensures that no single user provides dominant intra-cell interference (in the uplink). Near the cell edge, soft handover ensures good transmission quality through macrodiversity. Multiuser detection (MUD) is based on exploiting the structure of interference to mitigate its effect on the desired signal. Linear MUDs include decorrelating receivers and MMSE receivers. Nonlinear MUDs include the (optimum) multiuser MLSE as well as successive interference cancellation (SIC) and parallel interference cancellation (PIC). Time hopping impulse radio, mostly used in ultrawideband (UWB) communicat ions, represents each symbol by a sequence of pulses. Transmitted-reference signals allow simple receivers. View full abstract»

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      Orthogonal Frequency Division Multiplexing (OFDM)

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch19
      Page(s): 417 - 443
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      Orthogonal Frequency Division Multiplexing (OFDM) is a modulation scheme that converts a high-rate data stream into a number of low-rate streams that are transmitted on parallel subcarriers (tones). A digital implementation of this principle makes use of the inverse Fast Fourier Transform (IFFT). In delay-dispersive channels, intercarrier interference and intersymbol interference can be avoided, or at least mitigated, through a cyclic prefix at the beginning of each OFDM symbol, which converts the linear convolution of the signal with the channel impulse response into a circular convolution, and thus allows single-tap equalization. Coded OFDM allows to exploit the frequency diversity by distributing redundant information over different subcarriers; alternatively spreading information over subcarriers by a spreading sequence results in multicarrier CDMA (MC-CDMA), or (by spreading with an FFT sequence) single-carrier transmission with frequency-domain equalization (SC-FDE). Estimation of the channel transfer function, required for demodulation, is obtained from pilot symbols. By combining least-squares (LS) estimates with knowledge about the channel statistics, linear minimum mean square error (LMMSE) estimates can be obtained. Reduced-rank channel estimation can be obtained through the use of eigenvalue decompositions. A major drawback of OFDM is a high peak-to-average power ratio (PAPR), as it leads to spectral regrowth when nonlinear power amplifiers are used. Methods for its mitigation include coding for PAPR reduction, phase adjustment, and correction by multiplicative or additive functions. Adaptive modulation and coding adjusts the modulation and coding scheme on a particular subcarrier to the channel quality. Optimum power allocation to the subcarriers can be determined from the waterfilling rule. A combination of OFDM with TDMA or FDMA results in Orthogonal Fr equency Division Multiple Access (OFDMA). View full abstract»

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      Multiantenna Systems

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch20
      Page(s): 445 - 498
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter provides an overview of multiantenna systems. Smart antennas at the base station can increase capacity through Spatial Filtering for Interference Reduction (SFIR) or Space Division Multiple Access (SDMA). Transceiver structures include switched-beam antennas, and adaptive space-time processing, combined with temporal-reference (TR) and spatial reference (SR) algorithms, or blind algorithms. Random beamforming allows to exploit multiuser diversity. If channel state information (CSI) at the transmitter is needed but uplink and downlink are not reciprocal, codebook-based feedback of CSI is efficient, using, e.g., codebooks based on Grassmannian linepacking, or Kronecker models for correlated channels. MIMO (multiple-input ï¿¿ï¿¿ï¿¿ multiple-output) systems can be used for (i) beamforming, (ii) diversity, (iii) interference suppression, and (iv) spatial multiplexing. Transmission schemes with full CSI at the transmitter are based on singular value decomposition of the channel, appropriate linear precoding and waterfilling converts a MIMO channel to a number of parallel channels. Without CSI at the transmitter, layered space-time transmission schemes (BLAST) can be used. Equations for the ergodic capacity and outage capacity are given. Propagation channel characteristics, in particular line-of-sight conditions, channel correlation, and keyhole channels, need to be taken into account. Orthogonal space-time block codes (STBC) including Alamouti codes, and space-time trellis codes (STTC) can provide diversity. For the uplink of multiuser MIMO, joint detection at the BS is used. For the downlink, nonlinear (dirty paper coding, Tomlinson-Harashima precoding) or linear (block diagonalization, coordinated beamforming, joint Wiener filtering, channel inversion, regularized channel inversion, joint leakage suppression) techniques can be used. In base station cooperatio n (network MIMO, Cooperative MultiPoint CoMP) multiple BSs are connected to form a larger MIMO array. View full abstract»

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      Part Introduction

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.part5
      Page(s): 499 - 500
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      No abstract. View full abstract»

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      Cognitive Radio

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch21
      Page(s): 501 - 520
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      A cognitive radio adapts its transmission parameters to the environment. While fully cognitive radios (Mitola radios) theoretically have the best performance, dynamic spectrum access (DSA) or spectrum-sensing cognitive radio only adapts bandwidth, center frequency, and transmission time to the environment. In a hierarchical model, secondary users adapt such that they transmit only when they do not interfere with primary (preferred) users; this can be achieved by underlay, overlay, or interweaving. Interweaving has the secondary users transmit in the spectrum ï¿¿ï¿¿ï¿¿holesï¿¿ï¿¿ï¿¿. A first phase performs spectrum sensing of primary emissions (based on energy detection, matched filtering, cyclostationary detection, or wavelet detection), trading off false alarm probability with the missed detection probability. Next is the spectrum management phase, in which spectrum opportunity tracking is done. Finally, spectrum sharing, i.e., the assignment of the available spectrum to the different secondary users, can be achieved by centralized control, distributed control, or uncoordinated competition. Game theory is a key mathematical tool. For partial cooperation, referee-based solutions, threat and punishment, spectrum auctions, and bargaining solutions, can be used. Overlay approaches do not avoid simultaneous transmission primary and secondary user, but rather exploit it. If the secondary user has full knowledge of the primary usersï¿¿ï¿¿ï¿¿ message, it can use dirty paper coding to avoid creating interference, or even help the primary user in the transmission of its message. In underlay hierarchical access the secondary user transmits with such low power spectral density that it does not disturb the primary user: e.g., in ultrawideband (WB) communications the signal is spread over very large bandwidth through frequency hopping, coded OFDM, direct-sequence spread spectrum, or time-hopping impulse radio. Detect-and-avoid (DAA) can further reduce interference. View full abstract»

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      Relaying, MultiHop, and Cooperative Communications

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch22
      Page(s): 521 - 563
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter discusses basics of relaying, multi-hop transmission, and cooperative communications. We start with one source, one destination, and one relay. Various processing schemes (xF) at the relay (amplify-and-forward AF, decode-and-forward DF, compress-and-forward CF) together with various destination signal combining schemes, result in multi-hop xF, split-combine xF, diversity xF, nonorthogonal diversity xF, and intersymbol interference xF. Full-duplex and half-duplex constraints are considered. In two-phase protocols with parallel relays, cooperation schemes of the relays include relay selection, distributed beamforming, distributed space-time coding, coded cooperation, and mutual information accumulation using Fountain codes. Multihop relaying in larger networks require joint routing and resource allocation. Dijkstra and Bellman-Ford algorithms provide shortest-path routing. More generally we distinguish between proactive and reactive protocols. Noteworthy protocols include source routing, link-state routing (e.g., Optimized Link State Routing protocol OLSR), distance-vector routing (e.g., Destination-Sequenced Distance Vector DSDV and Ad hoc On-demand Distance Vector AODV), geography-based routing, and hierarchical routing. Node mobility is exploited in epidemic routing. Data-driven routing, e.g., directed diffusion, is used for sensor data. Stochastic network optimization (backpressure algorithms) forwards information without establishing explicit routes. Routing changes when nodes collaborate during each hop for better diversity and energy efficiency, e.g., in anypath routing (exploiting the broadcast effect), edge-disjoint shortest-path routing, and routing with nodes that use energy accumulation or mutual information accumulation. We finally discuss two-way relaying and general network coding, where nodes form combinations of received codewords, accordin g to an encoding vector, or use over-the-air combination of signals (compute-and-forward). View full abstract»

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      Video Coding

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch23
      Page(s): 565 - 585
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter discusses video coding, in particular video compression for wireless links. The most popular scheme is a block-based hybrid video coder, which combines transform coding and temporal prediction. Each picture is transformed into a domain where coarser quantization is admissible (e.g., by Discrete Cosine Transform DCT). Prediction includes both intraframe prediction (prediction of data from data within the same picture), and interframe prediction (motion compensated prediction). Entropy coding (Variable Length Coding, VLC), represents shorter codewords by higher probability symbols and longer codewords by lower probability symbols; e.g., Huffman coding and arithmetic coding. The chapter then discusses various video coding standards. These include the MPEG standards, and H.261, H.262, H.263, and H.264. Due to strong variations in data rates and transmission qualities in mobile environments, scalable video coding is important, which encodes the video source signal once, then decodes it according to specific delivery and receiver capabilities. We also discuss multiview video which supports three-dimensional (3D) video applications. Finally, we discuss implementation challenges and their countermeasures: (i) combatting loss of synchronization by resynchronization markers and/or reference picture selection; (ii) data partitioning for unequal error protection or transport prioritization; (iii) robust decoding by adding extra redundancy, such as in the Reversible Variable Length Codes (RVLC) and Multiple Description Coding (MDC); (v) error concealment at the decoder to decrease the visual impact of errors. The chapter is concluded by a discussion of video streaming. Popular protocols for streaming include the User Datagram Protocol (UDP), Real-time Transport Protocol (RTP), and Real Time Streaming Protocol (RTSP). View full abstract»

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      GSM Global System for Mobile Communications

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch24
      Page(s): 587 - 620
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter discusses the Global System for Mobile communications (GSM). The overall system consists of Base Station Subsystem (BSS), Network and Switching Subsystem (NSS), and Operation Support System (OSS). The BSS consists of Base Transceiver Stations (BTSs) and the Base Station Controllers (BSCs). The NSS consists of Mobile-services Switching Center (MSC), and several databases (e.g., HLR, VLR, EIR, and AUC). The OSS is responsible for organization and maintenance. We then discuss the air interface. Multiple access uses a combination of FDMA (with optional frequency hopping) and TDMA; FDD is used for duplexing. The time axis is divided into timeslots, which are grouped into frames, multiframes, and superframes. A combination of frequency band and timeslot index is a physical channel. GSM uses GMSK modulation; equalization is helped by a training sequence (midamble) in each timeslot. Coding employs unequal error protection, based on convolutional and/or block codes codes for bits created by the speech coder (regular pulse excited ï¿¿ï¿¿ï¿¿ long term prediction RPE-LTE). Interleaving over multiple slots is used. We next discuss the mapping of logical channels (types of data) to physical channels (time/frequency resources). Besides the (payload) traffic channels (TCHs), logical channels include various control channels. Next, we discuss time synchronization, including timing advance, and frequency synchronization. Data transmission in GSM includes circuit-switched transmission for low data rates, e.g., in Short Message Service (SMS) and packet-switched (e.g., General Packet Radio Service GPRS, see appendix). We then describe establishing connections and performing handovers. Various identity numbers, including MS ISDN, IMSI, MSRN, and IMEI are defined. The role of the SIM (Subscriber Identity Module) is analyzed. A discussion of various services enabled in GSM, and aspects of billing, conclude the chapter. View full abstract»

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      IS95 and CDMA 2000

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch25
      Page(s): 621 - 634
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter discusses the cellular standards IS-95 and CDMA 2000, often just called ï¿¿ï¿¿ï¿¿CDMAï¿¿ï¿¿ï¿¿ in the popular literature. The general system design (describing Base Station Subsystem (BSS), the Network and Switching Subsystem (NSS), and the Operation Support System (OSS) parallels that of GSM (see discussion there). The main chapter concentrates on the air interface of IS-95; the appendix discusses the enhancements of CDMA 2000 (including EV-DO). We first discuss coding, modulation, and spreading. Two different speech coders exist, the Qualcomm Code Excited Linear Prediction (QCELP), and the Enhanced Variable Rate Coder (EVRC). The output of the speech coder is FEC-encoded by addition of parity check bits (frame quality indicator, FQI) and convolutional encoding. The uplink uses M-ary orthogonal keying, where groups of encoded data are mapped onto Walsh codewords. These codewords are then spread by multiplication with a long spreading code, multiplied with short spreading sequences, and transmitted using Offset Quadrature Amplitude Modulation (OQAM). Databurst randomization and gating enable different data rates. The downlink data stream is first scrambled (without spreading by long spreading sequences). Spreading and channelization is done by multiplication with Walsh sequences. Finally, the output from the spreader is multiplied separately in the I- and Q-branch by short spreading sequence. IS-95 uses a combination of open-loop and closed-loop power control for the uplink, where the closed-loop consists of an outer and an inner loop. For the downlink, a coarse power control also exists. IS-95 distinguishes logical channels (types of data) and physical channels (time/frequency/code resources). Traffic channels, access channel, pilot channels, synchronization channel, paging channel, and power control channel are important examples. A discussion of the so ft handover, another key feature of CDMA systems, concludes the chapter. View full abstract»

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      WCDMA/UMTS

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch26
      Page(s): 635 - 663
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter gives an overview of the Wideband Code Division Multiple Access (WCDMA) standard for third generation (3G) cellular telephony ï¿¿ï¿¿ï¿¿ part of a group of standards known as Universal Mobile Telecommunication System (UMTS), Third Generation Partnership Project (3GPP), and International Mobile Telecommunications (IMT-2000). A WCDMA system consists of the Core Network (CN) and the UMTS Terrestrial Radio Access Network (UTRAN), which in turn consists of multiple Radio Network Subsystems (RNSs), containing Radio Network Controllers (RNCs), and base stations (Node-Bs). For the physical layer we concentrate on the UMTS-FDD mode. Aspects related to RF implementation include frequency bands, out-of-band emissions, and power classes. We then discuss logical channels or transport channels (describing the type of data that are transmitted) and physical channels (time/frequency/code resources). Transport channels include: common transport channels (broadcast channel BCH, paging channel PCH, random access channel RACH, forward access channel FACH, common packet Channel CPCH, and downlink shared channel DSCH), and dedicated (transport) channels DCH. Control and user data of a DCH are transmitted on the physical coded composite traffic channel (CCTrCH). We next describe coding, spreading, and multiplexing for uplink and downlink. The speech coder in UMTS is an adaptive multirate (AMR) coder. Data are segmented into blocks and encoded with convolutional or turbo codes. UMTS then uses channelization codes and scrambling codes for spreading and multiple access. Channelization codes are Orthogonal Variable Spreading Factor (OVSF) codes; spreading codes are either short codes (Kasami), or long codes (Gold). We finally describe physical layer procedures, including cell search and synchronization, the steps involved in establishing a connection, power control (which involves b oth closed-loop and open-loop control), transmit diversity, and overload control. View full abstract»

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      3GPP LongTerm Evolution

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch27
      Page(s): 665 - 698
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      We describe the 3GPP Long Term Evolution (LTE) standard, a member of the IMT-Advanced family for fourth-generation cellular communications. The system consists of radio access network (RAN) and core network (System Architecture Evolution SAE or Enhanced Packet Core EPC). Layers of the transmission protocol range from Packet Data Convergence Protocol (PDCP) to Radio Link Control (RLC), MAC, and PHY. After an overview of the physical layer, the division of the time axis into frames, subframes, and slots is discussed. The modulation format is OFDM for the downlink, and single-carrier transmission with frequency domain equalization (SC-FDE) for the uplink. We define resource element and resource blocks (RB). Data are mapped onto physical resources by first mapping symbols onto virtual resource blocks (VRBs), and from there to physical resource blocks (PRBs). There exist two types of reference signals RS (pilot tones): demodulation RS, and sounding RS; both based on Chadoff-Zhu sequences. Error control coding includes cyclic redundancy check (CRC), convolutional codes or turbo codes, and Hybrid ARQ (HARQ). Multiple-antenna techniques include Alamouti codes, possibly combined with antenna selection, for transmit diversity and (open-loop or closed-loop) spatial multiplexing. LTE distinguishes between logical channels and physical channels (time/frequency resources). Logical subchannels include Traffic channels (DTCH, MTCH) and Control channels (BCCH, PCCH, CCCH, DCCH, MCH). These are then mapped, via certain transport channels, to the physical channels. Primary and secondary synchronization signals carry timing information and cell ID. We discuss control information associated with downlink shared channel and uplink signaling (uplink control information, random access, and control signaling for the uplink shared channel). We also describe physical layer procedures, including establishing of a connection, retransmission methods, scheduling, power control, and handover. View full abstract»

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      WiMAX/IEEE 802.16

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch28
      Page(s): 699 - 729
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter gives an overview of WiMAX (Worldwide Interoperability for Microwave Access). A Wimax system consists of access service network (ASN) and internet-based connectivity service network (CSN). It specifies both a FDD mode when operating in paired spectrum, and a TDD mode for upaired spectrum. Multiple access capability is achieved by OFDMA, in particular different users are assigned different subcarriers. We first review the physical layer. Wimax uses OFDM (with cyclic prefix) with adaptive modulation and coding for both the uplink and the downlink. For error correction coding, convolutional codes and turbo codes are foreseen; further error correction is achieved by hybrid ARQ (HARQ) with chase combining or incremental redundancy. We then turn to the logical channels and physical channels (time/frequency resources). The time axis is divided into zones, frames, and subframes. In addition to the data bursts for the separate users, a frame contains preambles and control signaling (DL and UL-MAP, Frame Control Header FCH), and the ranging subchannel. Various schemes exist for subcarrier permutation, i.e., assigning data to the time/frequency resources (called subchannels and tiles, i.e., subcarriers or groups of subcarriers). Different types of permutations are defined for use in different zones: the PUSC (partial use of subcarriers), TUSC (tiled use of subcarriers), FUSC (full use of subcarriers), and AMC (Adaptive modulation and coding). We then describe multiple antenna techniques in Wimax. For space-time coding, Alamouti, antenna selection, antenna cycling, and/or beamforming is used. Spatial multiplexing is either open-loop, or closed-loop (precoding). We finally discuss link control, including establishing of a connection (including scanning, synchronization, initial ranging), scheduling and resource request, quality of service (QoS) control, power control, handover, and mobility support. View full abstract»

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      Wireless Local Area Networks

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch29
      Page(s): 731 - 750
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter gives an overview of the IEEE 802.11 (also known as WiFi) standard for wireless Local Area Networks (LANs). 802.11 actually is a family of standards, the (currently) most important ones of which are 802.11a, an OFDM-based system operating in the 5 GHz UNII band, 802.11g, a variant that operates in the 2.45 GHz ISM band, and 802.11n, the version using multiple antenna elements (MIMO) to achieve high throughput. The chapter first reviews the physical layer of 802.11a/g, which transmits packets of data employing OFDM modulation with cyclic prefix. Data are encoded with convolutional codes, possibly punctured to allow for different code rates. Adaptive modulation and coding is used to adapt to the quality of the link between transmitter and receiver, though the modulation format is the same on all OFDM subcarriers. For transmission, a preamble and a PLCP header are prepended to the encoded PSDU data that are received from the MAC layer, creating a PPDU. Synchronization is achieved by means of the PLCP preamble field. Channel estimation is enabled by a training sequence. In IEEE 802.11n, multiple-antenna techniques are used to increase the data rate. These include space-time coding including Alamouti coding and cyclic shift delay, antenna selection, spatial multiplexing and beamforming. Furthermore, advanced error correction coding, namely LDPC codes, can be used. Channel estimation is more complex due to the existence of multiple antenna elements; different forms are discussed. The chapter concludes with a discussion of multiple access in 802.11. It includes both contention-based and contention-free channel access methods, which are realized mostly through carrier sense multiple access and polling. The structure of the MAC frame formats is also described. View full abstract»

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      Exercises

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.ch30
      Page(s): 751 - 791
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      This chapter gives the exercises (problem statements) for the book ¿Wireless Communications¿ by Molisch. A solution manual is available to university instructors that adopt the book for their course; see wwww.wiley.com/go/molisch or wides.usc.edu/textbook. View full abstract»

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      References

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.refs
      Page(s): 793 - 816
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      No abstract. View full abstract»

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      Index

      Molisch, A.
      Wireless Communications

      DOI: 10.1002/9781119992806.index
      Page(s): 817 - 827
      Copyright Year: 2011

      Wiley-IEEE Press eBook Chapters

      No abstract. View full abstract»