Multi-Carrier and Spread Spectrum Systems: From OFDM and MC ...

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192 Implementation IssuesReceived power64-QAM16-QAM4-QAMFrequencyFigure 4-53Adaptive modulation per sub-carrier4.6.3 Adaptive Power ControlBesides the adaptation of coding and modulation, the transmit power of each OFDM symbolor each sub-carrier can be adjusted to counteract, for instance, the near–far problemor shadowing. A combination of adaptive coding and modulation (the first approach) withpower adjustment per OFDM symbol is usually adopted [20].4.7 RF IssuesA simplified OFDM transmitter front-end is illustrated in Figure 4-54. The transmittercomprises an I/Q generator with a local oscillator with carrier frequency f c ,low-passfilters, a mixer, channel pass-band filters, and a power amplifier. After power amplificationand filtering, the RF analogue signal is submitted to the transmit antenna. The receiverfront-end comprises similar components.Especially in cellular environments, due to employing low gain antennas, i.e. nondirectiveantennas, high power amplifiers are needed to guarantee a given coverage andN c -PointIDFT(complexdomain)D/AILocaloscillatorf cFilter(low pass)cos(.)sin(.)+Filter(pass band)HighpoweramplifierFilter(pass band)D/AQFilter(low pass)Figure 4-54Simplified OFDM transmitter front-end
RF Issues 193hence reduce, for instance, infrastructure costs by installing fewer base stations. Unfortunately,high power amplifiers are non-linear devices, where the maximum efficiencyis achieved at the saturation point. Furthermore, at high carrier frequencies (e.g. IEEE802.11h at 5 GHz) low cost RF transmit and receive oscillators can be applied at theexpense of higher phase noise.The main objective of this section is to analyze the performance of multi-carrier andmulti-carrier CDMA transmission with a high number of sub-carriers in the presence oflow cost oscillators with phase noise and HPAs with both AM/AM and AM/PM nonlinearconversions. First, a commonly accepted phase noise model is described. Afteranalyzing its effects in multi-carrier transmission with high order modulation, measuresin the digital domain based on common phase error (CPE) correction are discussed. Theeffects of two classes of non-linear power amplifiers are presented, namely traveling wavetube amplifiers (TWTAs) and solid state power amplifiers (SSPAs). Two techniques toreduce the effects of non-linear HPAs based on pre-distortion and spreading code selectionare discussed. Finally, in order to estimate the required transmit RF power for a givencoverage area, a link budget analysis is carried out.4.7.1 Phase NoiseThe performance of multi-carrier synchronization tracking loops depends strongly on theRF oscillator phase noise characteristics. Phase noise instabilities can be expressed andmeasured in the time and/or frequency domain.4.7.1.1 Phase Noise ModelingVarious phase noise models exist for the analysis of phase noise effects. Two often-usedphase noise models that assume instability of the phase only are described in the following.Lorenzian power density spectrumThe phase noise generated by the oscillators can be modeled by a Wiener–Lèvy process[68], i.e.θ(t) = 2π∫ t0µ(τ) dτ, (4.79)where µ(τ) represents white Gaussian frequency noise with power spectral density N 0 .The resulting power density spectrum is Lorenzian, i.e.2H(f) = ( ( ) 2πf 2). (4.80)πβ +βThe two-sided 3 dB bandwidth of the Lorenzian power density spectrum is given by β,also referred to as the line-width of the oscillator.Measurement-Based power density spectrumAn approach used within the standardization of DVB-T is the application of the powerdensity spectrum defined by [74]
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Multi-Carrier andSpread SpectrumSys
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This edition first published 2008©
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Contentsix4.3.2 One-Dimensional Cha
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ForewordThis book discusses multi-c
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Preface (First Edition)Nowadays, mu
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AcknowledgementsThe authors would l
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2 Introductionambitious technologic
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4 IntroductionTables 1 and 2 summar
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6 IntroductionPower densityTimeFreq
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8 Introductiona high immunity again
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10 Introductionprocessing gain P G
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12 Introductionand interactive mult
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14 Introduction[43] Saltzberg, B. R
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16 FundamentalsBSTSFigure 1-1Time-v
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18 Fundamentalswhere p =|a p | 2 (1
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20 Fundamentalssuch that the effect
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22 FundamentalsTable 1-2 Delay powe
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24 Fundamentals(i) Fixed Positioned
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26 Fundamentalson sub-channel n of
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28 Fundamentals10 010 −1OFDM (OFD
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30 Fundamentalsin order to achieve
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32 FundamentalsThe discrete length
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34 FundamentalsThe following matrix
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36 FundamentalsTable 1-11Wireless l
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38 FundamentalsFrequency hopping (F
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40 FundamentalsFinally, a threshold
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42 Fundamentals1.3.3 Applications o
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44 FundamentalsTable 1-12Radio link
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46 FundamentalsOrthogonalV-SF codeF
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{{48 Fundamentalsdata symbolsspread
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50 FundamentalsCellular Mobile Radi
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52 Fundamentals[27] Haindl B., “M
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2MC-CDMA and MC-DS-CDMAIn this chap
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MC-CDMA 57whered = (d (0) ,d (1) ,.
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MC-CDMA 59i.e. the spreading is per
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MC-CDMA 61Table 2-1 PAPR bounds of
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MC-CDMA 632.1.4.4 Rotated Constella
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MC-CDMA 65After inverse OFDM the re
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MC-CDMA 67and requires only informa
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MC-CDMA 69hard interference evaluat
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MC-CDMA 71Thedataofthedesireduserk
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MC-CDMA 73L corresponds to the spre
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MC-CDMA 752.1.7 Combined Equalizati
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MC-CDMA 77broadcasting, WLAN, and W
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MC-CDMA 792.1.8.1 Log-Likelihood Ra
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MC-CDMA 81For coded MC-CDMA systems
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MC-CDMA 83where Q different user gr
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MC-CDMA 85Table 2-2MC-CDMA system p
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MC-CDMA 87first iteration. The opti
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MC-CDMA 8910 010 −110 −2BER10
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MC-CDMA 9110 010 −1BER10 −210
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MC-CDMA 9310 010 −110 −2BER10
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MC-DS-CDMA 95c (k) (t)f 00d (k)S/P+
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MC-DS-CDMA 97The user-specific dela
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MC-DS-CDMA 9910 010 −1BER10 −21
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References 101[7] Brüninghaus K. a
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References 103[49] Steiner B., “U
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106 Hybrid Multiple Access SchemesI
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108 Hybrid Multiple Access Schemesw
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110 Hybrid Multiple Access Schemest
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112 Hybrid Multiple Access SchemesO
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114 Hybrid Multiple Access SchemesT
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116 Hybrid Multiple Access SchemesA
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120 Hybrid Multiple Access Schemest
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122 Hybrid Multiple Access SchemesA
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126 Hybrid Multiple Access Schemes[
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4Implementation IssuesA general PHY
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Multi-Carrier Modulation and Demodu
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Synchronization 139The performance
Page 161 and 162: Synchronization 141null symbol as a
Page 163 and 164: Synchronization 143resulting SNR ca
Page 165 and 166: Synchronization 145SNR Degradation
Page 167 and 168: Synchronization 147FFTr(k)estimated
Page 169 and 170: Synchronization 149the timing error
Page 171 and 172: Synchronization 151A first simple s
Page 173 and 174: Synchronization 153Transmitted 2 re
Page 175 and 176: Channel Estimation 155Special cases
Page 177 and 178: Channel Estimation 157The mean squa
Page 179 and 180: Channel Estimation 159by the second
Page 181 and 182: Channel Estimation 161Given the nor
Page 183 and 184: Channel Estimation 163and f D, filt
Page 185 and 186: Channel Estimation 16510 010 −110
Page 187 and 188: Channel Estimation 16710 010 −13
Page 189 and 190: Channel Estimation 169in order to r
Page 191 and 192: Channel Estimation 17110 010 −1BU
Page 193 and 194: Channel Estimation 173timefreq. 00
Page 195 and 196: Channel Coding and Decoding 1754.4.
Page 197 and 198: Channel Coding and Decoding 177Tabl
Page 199 and 200: Channel Coding and Decoding 179a (k
Page 201 and 202: Channel Coding and Decoding 181n rk
Page 203 and 204: Channel Coding and Decoding 183Bit
Page 205 and 206: Channel Coding and Decoding 185Bit
Page 207 and 208: Signal Constellation, Mapping, De-M
Page 209 and 210: Signal Constellation, Mapping, De-M
Page 211: Adaptive Techniques in Multi-Carrie
Page 215 and 216: RF Issues 195s(t)r(t)e jf(t)White n
Page 217 and 218: RF Issues 197receivedsignalto detec
Page 219 and 220: RF Issues 1994.7.2.1 Effects of Non
Page 221 and 222: RF Issues 2011e−011e−02UplinkDo
Page 223 and 224: RF Issues 203of data pre-distortion
Page 225 and 226: RF Issues 205Table 4-8Minimum total
Page 227 and 228: RF Issues 207Detection strategyIn t
Page 229 and 230: RF Issues 209above formula becomes(
Page 231 and 232: References 211[21] Fazel K., “Nar
Page 233 and 234: References 213[66] Nobilet S., Hela
Page 235 and 236: 5Applications5.1 IntroductionThe de
Page 237 and 238: Introduction 217high speed as well
Page 239 and 240: 3GPP Long Term Evolution (LTE) 219H
Page 241 and 242: 3GPP Long Term Evolution (LTE) 221U
Page 243 and 244: 3GPP Long Term Evolution (LTE) 2231
Page 247 and 248: 3GPP Long Term Evolution (LTE) 227T
Page 249 and 250: 3GPP Long Term Evolution (LTE) 229C
Page 257 and 258: WiMAX 237Table 5-12 Downlink LTE sp
Page 259 and 260: WiMAX 239Wi-FiBusinessTSWiMAX BSTSM
Page 261 and 262: WiMAX 241Table 5-16Summary of the I
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WiMAX 243WiMAXInteroperabilityInter
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WiMAX 245UNIAirinterfaceSNITerminal
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WiMAX 247Radio ResourceControlIniti
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WiMAX 249Frame n−1 Frame n Frame
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WiMAX 251Read RF-Channel ListScan F
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WiMAX 253NormaloperationTS measures
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WiMAX 255Table 5-18Example of some
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WiMAX 257Total bandwidth (between 1
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WiMAX 259Sub-carriers (frequency)n0
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ApplicationsWiMAX 261Table 5-23 Gen
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WiMAX 263Table 5-27(OFDMA)FEC codin
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WiMAX 265M-QAMMappingSTC withSpatia
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WiMAX 267Frame n−1 Frame n Frame
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WiMAX 269Table 5-29WirelessMAN-OFDM
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WiMAX 2710Power density in dB−25
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WiMAX 273Table 5-37diversityPeak da
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WiMAX 275Table 5-41DL link budget e
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Future Mobile Communications Concep
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Wireless Local Area Networks 283MTB
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Wireless Local Area Networks 285fre
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Interaction Channel for DVB-T: DVB-
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References 297Table 5-58Parameters
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References 299[32] Taoka H., Higuch
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302 Additional Techniques for Capac
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340 Definitions, Abbreviations, and
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350 SymbolsG l,lGG [j]h(t)h(τ,t)H(
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Index3GPP 218Adaptive techniques 19
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Index 355Forward error correction (
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Index 357Multi-carrier modulation a
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Index 359Maximum likelihood paramet
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