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9 Index ad hoc network 5 additive white Gaussian noise (AWGN) 29, 30, 166, 241 channel capacity 167 capacity-achieving AWGN channel codes 170, 171 packing spheres , 168, 169 channel resources 172 bandwidth reuse in cellular systems 175 8, 178 continuous-time AWGN channel 172 power and bandwidth downlink channel 235 6, 236 general case of superposition coding achieves capacity , 239 symmetric case of two capacity-achieving schemes formal derivation of capacity 526, infinite bandwidth uplink channel capacity via successive interference cancellation (SIC) , 229, 230 compared with conventional CDMA 232, 233 compared with orthogonal multiple access 232 4, 234 general K-user uplink capacity advanced mobile phone service (AMPS) 4 aggregate interference 141 aggregate interference level 130 CDMA uplink 133 Alamouti scheme for transmit diversity 73 4, 191 4, 192 analog memoryless channels angular domain representation of signals , 313 angular bases angular domain transformation as DFT 314 degrees of freedom , 318 diversity 322 3, 323 MIMO channels , 316 statistical modeling 317, 317 antenna diversity 71 multiple input multiple output (MIMO) channels 77 82, 78 receive diversity 71 3, 72 transmit and receive diversity 72 transmit diversity 72, 73 Alamouti scheme 73 4 determinant criterion for space-time code design 74 7 antennas arrays with only a line-of-sight path directional 121, 122 dumb antennas for opportunistic beamforming 263 6, 264, 265 dumb, smart and smarter , 269, 270 fast fading slow fading 266 geographically separated antennas receive antennas 305 6, 305 resolvability in angular domain 301 5, 303, 304, 305 transmit antennas 300 1, 300 multiple antennas in cellular networks downlink with multiple receive antennas 479, 482 downlink with multiple transmit antennas 479, 482 inter-cell interference management

10 555 Index MIMO uplink uplink with multiple receive antennas 476 8, 481 uniform linear antenna arrays 296 approximate universality 398, 400 code properties 404 5, 405 array gain 72 ArrayComm systems asymmetric fading downlink channels 251 bandwidth reuse in cellular systems 175 8, 178 bandwidth-limited systems 174, 174 baseband equivalent model for wireless channels 22 5, 23, 24 discrete-time model 25 8, 27, 28, 29 beam width 304 beamforming configuration 266 beamforming patterns 303, 304, 305 Bernoulli coin-flipped sequence 133 binary antipodal signaling 50 binary entropy binary entropy function 519, 519 binary erasure channels 517, 517 capacity 524 5, 524 binary phase-shift-keying (BPSK) 50, 60 coherent detection 53, 54 degrees of freedom 56 9 differential BPSK 58, 60 signal-to-noise ratio (SNR) 56 binary symmetric channels 517, 517 capacity 524, 524 block fading 199, 200 Bluetooth 5 burstiness averaging 141, 143 capacity-achieving AWGN channel codes 170 capacity of wireless channels 166, 214 see also multiuser capacity AWGN channel capacity 167 capacity-achieving AWGN channel codes 170, 171 packing spheres , 168, 169 repetition coding AWGN channel resources 172 bandwidth reuse in cellular systems 175 8, 178 continuous-time AWGN channel 172 power and bandwidth fading channels 186 7, fast fading , 216 frequency-selective fading channels 213 rate adaptation in IS , 210 receive diversity slow fading 187 9, 187, time and frequency diversity transmit diversity transmitter side information fading downlink channel 250 channel side information at receiver only full channel side information fading uplink channel 243, 250 fast fading full channel side information slow fading 243 4, 245 linear time-invariant Gaussian channels 179, frequency-selective channels 181 6, 181, 184, 185 MIMO channels 332 3, 345, 373 CSI at receiver performance gainss multiple input single output (MISO) channels reliable rate of communication 171 single input multiple output (SIMO) channels 179 capacity regions 428, 429, 537 9, 539 corner points , 540 carrier frequency 34 cellular networks 3, 3, bandwidth reuse 175 8, 178 capacity of cells 19 coverage of cells 19 frequency reuse historical development first generation systems 3 4 second generation systems 4 third generation systems 4 interference between adjacent cells 19 interference management 121 multiple access 121 multiple antennas downlink with multiple receive antennas 479, 482 downlink with multiple transmit antennas 479 inter-cell interference management MIMO uplink uplink with multiple receive antennas 476 8, 481 narrowband allocations in GSM performance 125 signal characteristics and receiver design narrowband systems 123 4, 124, 128 network and system design US frequency bands 11 wideband systems CDMA downlink 145 6, 146 CDMA uplink , 132

11 556 Index cellular networks (Cont.) OFDM sectorization 153 system issues 147 chain rule for entropies 520 chain rule for mutual information 521 channel inversion 204 compared with waterfilling 209 channel modeling 290 1, angular domain representation of signals , 313 angular bases angular domain transformation as DFT 314 degrees of freedom , 318 diversity 322 3, 323 MIMO channels , 316 statistical modeling 317, 317 MIMO channels antenna arrays with only a line-of-sight path geographically separated antennas 300 6, 300, 305 line-of-sight MISO channels line-of-sight plus one reflected path 306 9, 307, 308 line-of-sight SIMO channels 296 8, 296 MIMO fading channels 309 basic approach , 310 dependency on antenna spacing 323 7, 324, 325, 326, 327 i.i.d. Rayleigh fading model multipath channels 311 physical modeling free space, fixed transmit and receive antennas free space, moving antenna moving antenna, multiple reflectors power decay with distance and shadowing reflecting ground plate 17 18, 18 reflecting wall, fixed antenna 14 15, 14, 15 reflecting wall, moving antenna 15 17, 16, 17 channel side information (CSI) 207, 207 channel side information at the receiver (CSIR) 207, 207 MIMO channels 336 8, 346 capacity 346 performance analysis transceiver architecture 347 multiuser communications with MIMO systems uplink with multiple receive antennas 436 7, 437 uplink with multiple transmit and receive antennas 445 7, 446 channel uncertainty 102, 110 channel estimation non-coherent detection for DS spread-spectrum 103 5, 104, 105 other diversity scenarios 107 8, 108 channel-dependent scheduling 258, 259 channel-state independent coding scheme 366 chip rate 91 chip-synchronous users 132 circulant matrices 98 circular symmetric complex Gaussian random variables circular symmetry 29, 500 Clarke s model clustered response models 319 flat fading 38 40, 40 clustered response models Clarke s model 319 effect of carrier frequency 321 2, 321 total angular spread 322 general model indoor channel measurements 320 multipath environment 320 code division multiple access (CDMA) 4, 122, , compared with AWGN uplink channel 232, 233 downlink 145 6, 146 interference averaging and system capacity multiuser detection and ISI equalization 364 5, 365 system issues 147 uplink 131 2, 132 generation of pseudonoise sequences interference statistics IS-95 link design 136 7, 136 point-to-point link design power control 134, power control in IP , 139 soft handoff 134, , 139 coding 59 coding gains 49, 59, 66, 67, coherence bandwidth 15, 33, 34 coherence distance 15 coherence time 16, 31, 34 coherent combining 61 coherent detection in Rayleigh fading channels 52 6, 54 communication bandwidth 34 complex baseband equivalent 22 conditional entropy reliable communication 521 2

12 557 Index constructive wave interference 15 continuous-time AWGN channel 172 convex hull 438 Costa precoding see dirty paper precoding covariance matrix 499, 500 cyclic convolution 97 cyclic prefix operator 96, 96 convolution 97 data communications 4 D-BLAST multiplexing 368 coding across transmit antennas 371 2, 371 suboptimality universality decision-feedback equalizers (DFE) 90 decorrelator 80 1, 82 deep fade 55 degree-of-freedom limited systems 129 degrees of freedom 28, 110 angular domain representation of signals , 318 clustered response models BPSK and QPSK 56 9 multiple input multiple output (MIMO) channels 77 8, 78 downlink with multiple transmit antennas delay diversity 88 delay spread 15, 31 2, 34 delay-limited capacity 209 delay-limited power allocation 209 destructive wave interference 15 detection 49, 503 Rayleigh fading channels BPSK and QPSK 56 9 coherent detection 52 6, 54 diversity geometry of orthogonal modulation 57 non-coherent detection 50 2, 51, 54 summary of schemes 60 differential entropy 526 directional cosine 297, 304 direct-sequence (DS) spread-spectrum systems 91, 92, non-coherent detection 103 5, 104, 105 Rake receiver 91 3, 93 performance analysis 93 5 dirty paper (Costa) precoding 457 code design 463 4, 463 multiple transmit antennas single transmit antennas discrete Fourier transform (DFT) 97 angular domain transformation 314 Parseval theorem 182 discrete memoryless channels , 517, 518 Discrete Multi-Tone (DMT) systems 84 discrete-time baseband equivalent model for wireless channels 25 8, 27, 28, 29 diversity 49, 109 see also antenna diversity; frequency diversity; time diversity angular domain representation of signals 322 3, 323 Rayleigh fading channels diversity branches 60 error probability 62 diversity gains 49, 72 diversity multiplexing tradeoffs in MIMO channels MIMO Rayleigh channel four schemes 392 4, 392, 393, 393 optimal tradeoff formulation MISO Rayleigh channel n n MIMO i.i.d. Rayleigh channel geometric interpretation 397 8, 397 optimal tradeoff 395 6, 396 parallel Rayleigh channel 390 1, 391 scalar Rayleigh channel optimal tradeoff PAM and QAM 386 9, 388, 389 Doppler shift 21, 34 moving antennas 13, 14, 16 Doppler spectrum 40, 40 Doppler spread 16 17, 27, 30 1, 34 downconversion 22, 24 downlink 4, 121 duplexer 121 dynamic programming 90, 90 eigenmode of a channel (eigenchannel) 293 energy detectors 51 entropy 518 chain rule 520 differential entropy 526 epsilon ( )-outage capacity 188, 189, 191 ergodicity 201 stationary ergodic fading 534 error propagation 355 fade margin 130 fading 1 large-scale fading 10, 11 small-scale fading 10 fast fading channels 31, 34 capacity 199, 201 2, 216 derivation , 200 MIMO channels performance comparison scalar channels transmitter side information 204 6, 206

13 558 Index fast fading channels (Cont.) downlink with multiple transmit antennas 468 full CSI 468 receiver CSI receiver CSI and partial CSI at base-station multiuser capacity AWGN uplink full channel side information multiuser communications with MIMO systems full CSI receiver CSI 436 7, 437 uplink with multiple transmit and receive antennas 445 receiver CSI 445 7, 446 flash-ofdm flat fading channels 33, 34 Clarke s model 38 40, 40 foward channel 4, 121 frequency coherence 32 frequency diversity basic concept 83 4 direct-sequence (DS) spread-spectrum 91, 92, performance analysis 93 5 Rake receiver 91 3, 93 error probability analysis 86 8 extensions geometric view 197 8, 198 implementing MLSD 88 91, 88 orthogonal frequency division multiplexing (OFDM) systems 95 9, 102, 108, 108 block length outage performance of parallel channels single-carrier with ISI equalization 84 5, 101 frequency-selective channel viewed as MISO channel 85, 85 frequency division duplex (FDD) systems 69, 121 frequency hopping 71 frequency reuse 122, frequency-selective channels fading channels 33, 34 capacity 213 multiuser capacity linear time-invariant Gaussian channels coding across sub-carriers transformation to parallel channel 181 3, 181 waterfilling power allocation 183 5, 184, 185 Gaussian noise, detection in complex vector space detection scalar detection 503 4, 504 vector space detection 504 7, 505, 506 Gaussian noise, estimation in complex vector space estimation scalar estimation vector space estimation Gaussian random variables complex Gaussian random vectors real Gaussian random vectors , 498, 499 scalar real Gaussian random variables 496 7, 497 Global System for Mobile (GSM) communication systems 4 narrowband allocations performance 125 signal characteristics and receiver design time diversity 69 71, 70 Hadamard sequences 146 handoff 121 see also soft handoff Hermitian matrices 75 hopping patterns 150 2, 151 i.i.d. Gaussian code 170 ideal interweaving imperfect power control averaging 141 impulse response baseband equivalent 25 fading multipath channel 21 information theory 166, 167, 516 capacity of fast fading channels MIMO channels scalar channels discrete memoryless channels , 517, 518 entropy, conditional entropy and mutual information formal derivation of AWGN capacity 526, analog memoryless channels multiple access channels capacity region 537 9, 539 capacity region corner points , 540 fast fading uplink noisy channel coding theorem 521 achieving upper bound operational interpretation reliable communication and conditional entropy outage formulation 536 7

14 559 Index receiver optimality fading channels 364 MMSE is information lossless time-invariant channel sphere-packing interpretation 529 achievability 530 2, 531 converse , 530 time-invariant parallel channel inner codes 194 inter-cell interference interference 1 interference averaging 141 interference avoidance 271 interference diversity 141 interference nuller 81, 350 interference-limited rate 235 interference-limited systems 129 capacity 142 interleaving 59, 60, 61 inter-symbol interference (ISI) 83 equalization and CDMA multiuser detection 364 5, 365 IS-856 downlink , 210 prediction uncertainty rate control rate versus power control 210 IS-95 link CDMA downlink 146, 146 CDMA uplink 136 7, 136 power control 138 9, 139 Jensen inequality 202 3, 245, 295, 338 Kuhn Tucker condition 183 large-scale fading 10, 11, 40 Latin squares 150 orthogonal 151 linear decorrelator 434 geometric derivation , 350, 351 performance for deterministic H matrix 352 performance in fading channels 352 4, 353, 354 linear equalizers 90 linear time-invariant (LTI) channel 13 linear time-varying system model for wireless channels 20 2 local area networks (LANs) ad hoc network 5 wireless systems 5 log-likelihood ratio 51 low-complexity detection 80 1, 82 macrodiversity 59, 130 matched filter 61 maximal ratio combining 61, 140 maximum length shift register (MLSR) maximum likelihood (ML) rule 51, 503, 504 maximum likelihood sequence detection (MLSD) 86 Viterbi algorithm 88 91, 88 memoryless channels minimum Hamming distance 69 minimum mean square error (MMSE) equalizers 90, 333 information theoretic optimality fading channels 364 MMSE is information lossless time-invariant channel linear MMSE receiver decorrelator limitations 356 7, 357 derivation , 358 MMSE SIC 361 2, 361, 362 performance 360, 361 performance enhancement by MMSE decoding , 460 mobile switching center (MSC) see mobile telephone switching office (MTSO) mobile telephone switching office (MTSO) 3 4 multipath fading 11, 16 multiple input multiple output (MIMO) channels 290 1, see also multiuser communications with MIMO systems antenna diversity degrees of freedom 77 8, 78 low-complexity detection 80 1, 82 spacial multiplexing summary of 2 2 schemes 82 capacity 332 3, 345, 373 CSI at receiver performance gainss D-BLAST archicture 368 coding across transmit antennas 371 2, 371 suboptimality diversity-multiplexing tradeoffs 383, MIMO Rayleigh channel formulation MIMO Rayleigh channel 392, 393, 393 MISO Rayleigh channel n n MIMO i.i.d. Rayleigh channel 395 8, 396, 397 parallel Rayleigh channel 390 1, 391 scalar Rayleigh channel , 388, 389 full CSI 346 capacity 346 performance analysis transceiver architecture 347

15 560 Index multiple input multiple output (MIMO) channels (Cont.) modeling fading channels 309 angular domain transformation , 316 basic approach , 310 dependency on antenna spacing 323 7, 324, 325, 326, 327 i.i.d. Rayleigh fading model multipath channels 311 multiplexing architectures 332 3, 373 fast fading channels V-BLAST multiplexing capability 291, 309 capacity via singular value decomposition 291 4, 293 rank and condition number physical modeling antenna arrays with only a line-of-sight path geographically separated antennas 300 6, 300, 303, 304, 305 line-of-sight MISO channels line-of-sight plus one reflected path 306 9, 307, 308 line-of-sight SIMO channels 296 8, 296 receiver architectures information theoretic optimality linear decorrelator , 350, 351, 353, 354 linear MMSE receiver , 357, 358, 361, 362 successive cancellation 355 6, 355 slow fading channels high SNR 368 universal space-time codes 383, 398, 411, design criterion properties of approximately universal codes QAM is approximately universal for scalar channels universality of D-BLAST multiple input single output (MISO) channels 73 frequency-selective channels 85, 85 large transmit antenna arrays 344, 345 linear time-invariant Gaussian channels modeling Rayleigh fading universal code design 407, 410 conversion to parallel channels design criterion viewed as parallel channels 407 8, multiplexing D-BLAST architecture 368 coding across transmit antennas 371 2, 371 suboptimality MIMO architectures 332 3, 373 fast fading channels V-BLAST receiver architectures information theoretic optimality linear decorrelator , 350, 351, 353, 354 linear MMSE receiver , 357, 358, 361, 362 successive cancellation 355 6, 355 slow fading MIMO channels high SNR 368 multiuser capacity see also capacity of wireless channels AWGN downlink 235 6, 236, 241 general case of superposition coding achieves capacity , 239 symmetric case of two capacity-achieving schemes AWGN fading downlink 250 channel side information at receiver only full channel side information AWGN fading uplink 243, 250 fast fading slow fading 243 4, 245 AWGN uplink capacity via successive interference cancellation (SIC) , 229, 230 compared with conventional CDMA 232, 233 compared with orthogonal multiple access 232 4, 234 general K-user uplink capacity frequency-selective fading channels multiuser communications with MIMO systems downlink with multiple receive and transmit antennas 471 3, 471, 472, 481 downlink with multiple transmit antennas 448, 448 degrees of freedom fast fading precoding for downlink precoding for interference known at transmitter , 455, 456, 457 uplink-downlink duality and transmit beamforming multiple antennas in cellular networks uplink 478 9

16 561 Index uplink with multiple receive antennas 426, 426 fast fading multiuser diversity slow fading 433 6, 435, 436 space-division multiple access (SDMA) space-division multiple access (SDMA) capacity region , 429 system implications 431 2, 432 uplink with multiple transmit and receive antennas 442 fast fading SDMA 442 4, 443, 444 system implications 444 5, 445 multiuser diversity 228, 229, channel prediction and feedback fair scheduling 258 multiuser diversity gain in practice 261 2, 261, 262 proportional fair scheduling , 259 superposition coding 260 1, 261 multicell systems multiuser communications with MIMO systems 439 one user at a time policy optimal power allocation policy 440 2, 441 multiuser diversity gain 253 6, 254 multiuser versus classical diversity 256 system aspects system view mutual information chain rule 521 narrowband systems 122, 123 4, 124, 128 allocation in GSM system performance 125 signal characteristics and receiver design nearest neighbor rule 504, 505 near-far problem 129, 232 nested lattice codes 463, 463 noise spheres 169, 529, 530 non-coherent detection direct-sequence (DS) spread-spectrum 103 5, 104, 105 Rayleigh fading channels 50 2, 51, 54 one-ring model 39 opportunistic beamforming 229, 275 6, 469, 469 dumb antennas 263 6, 264, 265 dumb, smart and smarter , 269, 270 fast fading slow fading 266 opportunistic communications 166, 228 9, 442 opportunistic nulling 271 opportunistic orthogonal coding optimality principle of dynamic programming 90, 90 orthogonal codes 175 orthogonal frequency division multiplexing (OFDM) systems 84, 95 9, 102, 108, 108, 122, 148 allocations design principles block length flash-ofdm hopping pattern signal characteristics and receiver design 152 transmission and reception schemes 99 orthogonal Latin squares 151 orthogonal multiple access compared with AWGN uplink channel capacity 232 4, 234 uplink with multiple receive antennas 476, 481 orthogonality principle 510 orthonormal set of waveforms 29 outage 138, 187, 190 formulation parallel channels 199 Rayleigh fading 188 time and frequency diversity outer codes 194 out-of-cell interference averaging 141 pairwise error probability 75 parallel channels linear time-invariant Gaussian channels 181 3, 181 outage 199 time and frequency diversity time-invariant parallel channel universal space-time codes 400 6, 402, 403, 405, waterfilling power allocation 204 5, 206, Parseval theorem for DFTs 182 passband spectrum 23 peak to average power ratio (PAPR) 126 peak transmit power 126 performance gains in MIMO fading channels 338, 348 high SNR regime large antenna array regime 341 3, 342, 343 low SNR regime 340, 341 periodic hopping patterns 150, 151 phased-array antenna 298 power decay 18 19

17 562 Index power gain 72, 179 power-limited systems 174, 174 processing gain 91, 135 pseudo-covariance matrix 500, 501 pseudonoise (PN) 91 Q function 496, 497 quadrature amplitude modulation (QAM) 23 4 approximately universal for scalar channels quadrature phase-shift-keying (QPSK) 60 degrees of freedom 56 9 differential QPSK 60 quarter circle law 342, 342 quasi-static scenario 187 radio broadcast systems (AM, FM, etc.) 5 Rake receiver 91 3, 93 performance analysis 93 5 rate-splitting 231 ray tracing 14 Rayleigh fading MIMO Rayleigh channel four schemes 392 4, 392, 393, 393 optimal tradeoff channel detection coherent detection 52 6, 54 non-coherent detection 50 2, 51, 54 dumb antennas for opportunistic beamforming 267, 268 MIMO capacity 338 9, 339, MISO channels multiuser diversity gain 253 4, 253 n n MIMO i.i.d. Rayleigh channel geometric interpretation 397 8, 397 optimal tradeoff 395 6, 396 outage probability 188 parallel channels 390 1, 391 scalar channels optimal tradeoff PAM and QAM 386 9, 388, 389 Rayleigh random variables 501 receive beamforming 179, 273, 358, 449 receive diversity , 195 receiver architectures information theoretic optimality fading channels 364 MMSE is information lossless time-invariant channel linear decorrelator geometric derivation , 350, 351 performance for deterministic H matrix 352 performance in fading channels 352 4, 353, 354 linear MMSE receiver decorrelator limitations 356 7, 357 derivation , 358 MMSE SIC 361 2, 361, 362, 427, performance 360, 361 successive cancellation 355 6, 355 reliability of air interface 2 repetition coding 49, 59, 60 4, 65 AWGN channel capacity packing spheres 168, 169 transmit diversity reverse channel 4, 121 richly scattered environment 328 Rician fading 37 dumb antennas for opportunistic beamforming 267 8, 268 multiuser diversity gain 253 4, 253 rotation coding 64 6, 65 scattering reflections 20 scheduler 258, 259 sectorization 121 2, 122 selection combining 140 separation of time-scales 145 shadowing 19 signal-to-interference plus noise ratio (SINR) 122 CDMA uplink 135 signal-to-noise ratio (SNR) binary phase-shift-keying (BPSK) 56 quadrature phase-shift-keying (QPSK) 56 Rayleigh fading channels 109 coherent detection 53, 54, 55 non-coherent detection 52 sinc(t) function 25 single input multiple output (SIMO) channels large receive antenna arrays 344, 345 linear time-invariant Gaussian channels 179 modeling 296 8, 296 singular value decomposition (SVD) 291 4, 293 slow fading channels 31, 34 capacity 187 9, 187, transmitter side information 204 dumb antennas for opportunistic beamforming 266 multiplexing architecture for MIMO high SNR 368 multiuser capacity AWGN uplink 243 4, 245 multiuser communications with MIMO systems 433 6, 435, 436 small-scale fading 10, 41 soft capacity limit 130

18 563 Index soft handoff 130 see also handoff CDMA downlink 146 CDMA uplink , 139 softer handoff 140 space-division multiple access (SDMA) ArrayComm systems capacity region , 429 orthogonal multiple access uplink with multiple receive antennas 476 8, 481 uplink with multiple transmit antennas 442 4, 443, 444 space-time codes 73 determinant criterion 74 7 spatial multiplexing 79 80, 290 1, 308 see also V-BLAST multiplexing spatial signature 297 spectral efficiency 2, 143 4, 144, 172, 173 specular path 37 sphere covering 458 sphere hardening effect 169 sphere packing , 168, 169, 458, 529 upper bound , 530 squared product distance 66 square-law detectors 51 stationary ergodic fading 534 statistical multiplexing 130, 144 successive cancellation 228 successive interference cancellation (SIC) 228, 275, 333 AWGN uplink channel , 229, 230 implementation issues MMSE SIC receivers 361 2, 361, 362, 427, receiver architectures 355 6, 355 sum capacity 230 superposition coding 228, 275 general case , 239 multiuser diversity 260 1, 261 symmetric case 237 8, 238 symbol-by-symbol precoding 454 7, 455, 456, 457, 461 decoding 462 performance transmitter knowledge of interference 461 3, 462 symmetric capacity 230, 235 system capacity 141 system view 2 tap gain auto-correlation function 37 8 time diversity 60, 61 code design criterion 68 extensions geometric view 197 8, 198 Global System for Mobile (GSM) systems 69 71, 70 other coding systems 64 7, 65 outage performance of parallel channels repetition coding 60 4, 65 time division duplex (TDD) 121 time-division multiple access (TDMA) 4 Global System for Mobile (GSM) systems 69 transition probabilities 516 transmit beamforming 180, 340, transmit diversity 191, 195 Alamouti scheme 191 4, 192 repetition coding transmit power control 137 transmitter-centric scheme 466 trellis representation 89, 89 ultra-wideband (UWB) 5, 32 uncertainty sphere 531, 531 underspread channels 22, 34 uniform linear antenna arrays 296 universal frequency reuse universal space-time codes 383 4, 398, 400, bit-reversal scheme design criterion 400 2, 402, 403 high SNR MIMO channels 411, design criterion downlink 415 properties of approximately universal codes universality of D-BLAST MISO channels 407, 410 conversion to parallel channels design criterion viewed as parallel channels 407 8, 408 properties of approximately universal codes 404 5, 405 QAM is approximately universal for scalar channels universal frequency reuse 122 upconversion 22, 24 uplink 4, 121 uplink-downlink duality 450 2, 451 V-BLAST multiplexing 332, 333 see also spatial multiplexing MIMO architecture virtual channels 150, 151 Viterbi algorithm 83 4, 88 91, 88 voice communications 4 waterfilling power allocation 183 5, 184, 185, 204 6, 206, compared with channel inversion 209