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

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120 Hybrid Multiple Access Schemestional measures like channel coding or applying multiple transmit/receive antennas. Asa TDMA system, the instantaneous transmitted power in the terminal station is high,which requires more powerful high power amplifiers than for FDMA or OFDMA systems.Furthermore, the MC-TDMA system as an OFDM system needs a high outputpower back-off.As shown in Figure 3-9, the terminal station of an MC-TDMA system is synchronizedto the base station in order to reduce the synchronization overhead. The transmitter of theterminal station extracts from the demodulated downlink data such as MAC messages,burst allocation, power control and timing advance, and further clock and frequencysynchronization information. In other words, the synchronization of the terminal stationis achieved using the MAC control messages to perform time synchronization andusing frequency information issued from the terminal station downlink demodulator (therecovered base station system clock). MAC control messages are processed by the MACmanagement block to instruct the terminal station modulator on the transmission resourcesassigned to it and to tune the access. Here, the pilot/reference symbols are inserted at thetransmitter side to ease the burst synchronization and channel estimation tasks at the basestation. At the base station, the received burst issued by each terminal station is detectedand multi-carrier demodulated.It should be emphasized that the transmitter and receiver structure of an MC-TDMAsystem is quite similar to that of an OFDM/OFDMA system. The same components,such as FFT, channel estimation, equalization, and soft channel decoding, can be used forboth, except that for an MC-TDMA system a burst synchronization is required, equivalentTS ReceiverBS TransmitterMACmessagesClock,frequencyDownlinkMedium Access Controller(MAC)Clock,frequencyMAC- Time burst allocation,- Power control, RangingSynchronizationSynchronizationInterleaving,EncodingSymbol mappingMulti-carrier modulator(IFFT)Terminal StationMC-TDMA TransmitterTDMA burst formattingD/A & RFPilot/Ref.insertionRFoutputUplinkRFinputRF & A/DBurst synchronizationMulti-carrier demodulator(IFFT)Base StationMC-TDMA ReceiverEqualization, DemappingDeinterleaving, DecodingChannelestimationFigure 3-9General MC-TDMA conceptual transceiver
Ultra Wideband Systems 121to a single-carrier TDMA system. Furthermore, a frequency synchronous system wouldsimplify the MC-TDMA receiver synchronization tasks.Combining OFDMA and MC-TDMA achieves a flexible multi-user system with highthroughput [9].3.4 Ultra Wideband SystemsThe technique for generating an ultra wideband (UWB) signal has existed for more thanthree decades [27], which is better known to the radar community as a baseband carrierless short pulse [1]. A classical way to generate a UWB signal is to spread the datawith a code with a very large processing gain, i.e. 50 to 60 dB, resulting in a transmittedbandwidth of several GHz. Multiple access can be realized by classical CDMA, wherefor each user a given spreading code is assigned. However, the main problem of such atechnique is its implementation complexity.As the power spectral density of the UWB signal is extremely low, the transmittedsignal appears as a negligible white noise for other systems. In the increasingly crowdedspectrum, the transmission of the data as a noise-like signal can be considered a mainadvantage for the UWB systems. However, its drawbacks are the small coverage and thelow data rate for each userIn References [25] and [37] an alternative approach compared to classical CDMA isproposed for generating a UWB signal that does require sine-wave generation. It is basedon time-hopping spread spectrum. The key advantages of this method are the ability toresolve multi-paths and the low complexity technology availability for its implementation.3.4.1 Pseudo-Random PPM UWB Signal GenerationThe idea of generating a UWB signal by transmitting ultra-short Gaussian monocycleswith controlled pulse-to-pulse intervals can be found in Reference [25]. The monocycleis a wideband signal with center frequency and bandwidth dependent on the monocycleduration. In the time domain, a Gaussian monocycle is derived by the first derivative ofthe Gaussian function, given by√ eπs(t) = 6a3( )t t 2τ e−6π τ , (3.22)where a is the peak amplitude of the monocycle and τ is the monocycle duration. In thefrequency domain, the monocycle spectrum is given by√S(f) =−j 2fτ2 eπ π3 2 e− 6 (f τ)2 , (3.23)with center frequency and bandwidth approximately equal to 1/τ.In Figure 3-10, a Gaussian monocycle with τ = 0.5 ns duration is illustrated. This monocyclewill result in a center frequency of 2 GHz with 3 dB bandwidth of approximately2 GHz (from 1 to 3.16 GHz). For data transmission, pulse position modulation (PPM) canbe used, which varies the precise timing of transmission of a monocycle about the nominalposition. By shifting each monocycle’s actual transmission time over a large time frame
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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
Page 89 and 90: MC-CDMA 69hard interference evaluat
Page 91 and 92: MC-CDMA 71Thedataofthedesireduserk
Page 93 and 94: MC-CDMA 73L corresponds to the spre
Page 95 and 96: MC-CDMA 752.1.7 Combined Equalizati
Page 97 and 98: MC-CDMA 77broadcasting, WLAN, and W
Page 99 and 100: MC-CDMA 792.1.8.1 Log-Likelihood Ra
Page 101 and 102: MC-CDMA 81For coded MC-CDMA systems
Page 103 and 104: MC-CDMA 83where Q different user gr
Page 105 and 106: MC-CDMA 85Table 2-2MC-CDMA system p
Page 107 and 108: MC-CDMA 87first iteration. The opti
Page 109 and 110: MC-CDMA 8910 010 −110 −2BER10
Page 111 and 112: MC-CDMA 9110 010 −1BER10 −210
Page 113 and 114: MC-CDMA 9310 010 −110 −2BER10
Page 115 and 116: MC-DS-CDMA 95c (k) (t)f 00d (k)S/P+
Page 117 and 118: MC-DS-CDMA 97The user-specific dela
Page 119 and 120: MC-DS-CDMA 9910 010 −1BER10 −21
Page 121 and 122: References 101[7] Brüninghaus K. a
Page 123: References 103[49] Steiner B., “U
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Page 136 and 137: 116 Hybrid Multiple Access SchemesA
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Page 149 and 150: 4Implementation IssuesA general PHY
Page 151 and 152: Multi-Carrier Modulation and Demodu
Page 159 and 160: 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
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Channel Estimation 17110 010 −1BU
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Channel Estimation 173timefreq. 00
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Channel Coding and Decoding 1754.4.
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Channel Coding and Decoding 177Tabl
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Channel Coding and Decoding 179a (k
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Channel Coding and Decoding 181n rk
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Channel Coding and Decoding 183Bit
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Channel Coding and Decoding 185Bit
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Signal Constellation, Mapping, De-M
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Signal Constellation, Mapping, De-M
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Adaptive Techniques in Multi-Carrie
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RF Issues 193hence reduce, for inst
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RF Issues 195s(t)r(t)e jf(t)White n
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RF Issues 197receivedsignalto detec
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RF Issues 1994.7.2.1 Effects of Non
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RF Issues 2011e−011e−02UplinkDo
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RF Issues 203of data pre-distortion
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RF Issues 205Table 4-8Minimum total
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RF Issues 207Detection strategyIn t
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RF Issues 209above formula becomes(
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References 211[21] Fazel K., “Nar
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References 213[66] Nobilet S., Hela
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5Applications5.1 IntroductionThe de
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Introduction 217high speed as well
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3GPP Long Term Evolution (LTE) 219H
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3GPP Long Term Evolution (LTE) 221U
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3GPP Long Term Evolution (LTE) 2231
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3GPP Long Term Evolution (LTE) 227T
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3GPP Long Term Evolution (LTE) 229C
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WiMAX 237Table 5-12 Downlink LTE sp
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WiMAX 239Wi-FiBusinessTSWiMAX BSTSM
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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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