Wideband OFDM System for Indoor Communication at 60 GHz [Elektronische Ressource] / Maxim Piz. Betreuer: Rolf Kraemer

Maxim Piz

Informations

• Publié par: brandenburgische_technische_universitat_cottbus
• Publié le: 01 janvier 2011
• Nombre de lectures: 29
• Langue: English
• Poids de l'ouvrage: 8 Mo

Extrait

Wideband OFDM System for Indoor
Communication at 60 GHz
Von der Fakultät für Mathematik, Naturwissenschaften und Informatik
der Brandenburgischen Technischen Universität Cottbus
zur Erlangung des akademischen Grades
Doktor der Ingenieurwissenschaften
genehmigte Dissertation
vorgelegt von
Diplom-Ingenieur
Maxim Piz
geboren am 5. 1. 1975 in Czernowitz / Ukraine
Gutachter: Prof. Dr.-Ing. Rolf Kraemer
Gutachter: Prof. Dr.-Ing. Hermann Rohling
Gutachter: Prof. Dr.-Ing. Heinrich Theodor Vierhaus
Tag der mündlichen Prüfung: 16. 12. 2010This work has been done at the Leibniz Institute IHP Microelectronics in Frankfurt (Oder) and is based
on contributions to the German WIGWAM and EASY-A project. These projects have been funded by
the German Federal Ministry of Education and Research (BMBF). The thesis has been submitted at the
Brandenburgische Technische Universität Cottbus.
Acknowledgements
I wish to express my utmost gratitude to my supervisors, Prof. Dr. Rolf Kraemer and Dr.
Eckhard Grass, who helped me with their invaluable assistance, support and guidance of the
work and their careful review of the manuscript. Without my supervisors, this work would not
have been possible.
Furthermore, I very thankfully acknowledge Prof. Dr. Hermann Rohling and Prof. Dr. Hein-
rich Theodor Vierhaus for their thorough reviews and profound suggestions for an improve-
ment of the manuscript.
In addition, my special thanks go to Prof. Dr. Jörg Nolte, Dean of the Faculty of Mathematics,
Sciences and Computer Sciences at the University of Cottbus, who directed the defence of my
work in a very friendly and pleasant way.
Further acknowledgements go to Dr. Frank Herzel, who has let me share some of his expert
knowledge about oscillators and phase locked loops, and Dr. Milos Krstic and Dipl.-Ing.
Markus Ehrig, who both contributed to the implementation of the first 60 GHz baseband
system. It was a great pleasure to work with them. I also have to thank Dr. Michael Methfessel
for our fruitful technical discussions and his Latex support.
I would like to thank all my other colleagues at the Systems Department of IHP, who all
contributed to a friendly working atmosphere and were always ready to provide help.
Last but not least, I would like to thank my family who has been a backbone during my whole
life, in good and bad times, and were ready to support me whenever needed.
Maxim PizContents
1 Introduction 1
2 Radio link model for 60 GHz transmission 6
2.1 Radio link based on direct conversion scheme . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Phase noise model for voltage controlled oscillator (VCO) . . . . . . . . . . . . . . . 8
2.3 Clock Jitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.4 Analog-to-digital and digital-to-analog conversion . . . . . . . . . . . . . . . . . . . . 12
2.5 Power amplifier nonlinearity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.6 I/Q mismatch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.7 Summarized link model, parameter investigation . . . . . . . . . . . . . . . . . . . . 22
3 Channel models for 60 GHz radio communication 25
3.1 General characteristics of 60 GHz indoor channels . . . . . . . . . . . . . . . . . . . 25
3.2 HHI Channel model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.3 TG3c channel model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4 OFDM under non ideal link conditions 34
4.1 OFDM modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.2 BPSK, QPSK and QAM-constellation mapping on subcarriers . . . . . . . . . . . . . 35
4.3 Degradation of OFDM due to imperfect synchronization and RF impairments . . . . . 36
4.3.1 Residual intersymbol interference due to insufficient guard time length . . . . 37
4.3.2 Degradation due to frequency offset and phase noise . . . . . . . . . . . . . . 41
4.3.3 Degradation due to sampling clock frequency mismatch . . . . . . . . . . . . 46
4.4 Carrier frequency offset estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.4.1 Phase-noise induced frequency error . . . . . . . . . . . . . . . . . . . . . . . 49
4.4.2 AWGN noise induced frequency error . . . . . . . . . . . . . . . . . . . . . . 50
4.4.3 Probability to exceed a given absolute frequency error . . . . . . . . . . . . . 52
5 PHY layer specification and performance investigation 54
5.1 Overview and general considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
5.2 Investigation of basic OFDM modulation parameters . . . . . . . . . . . . . . . . . . 57
5.2.1 Signal bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
5.2.2 DFT size, guard length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
5.2.3 Data, pilot and guard subcarriers . . . . . . . . . . . . . . . . . . . . . . . . . 59
5.2.4 Pulse waveform and signal spectrum . . . . . . . . . . . . . . . . . . . . . . . 60
5.3 Selection of a channel code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
5.4 Stream arrangement and frame structure . . . . . . . . . . . . . . . . . . . . . . . . . 62
5.5 Interleaver design and convolutional code performance . . . . . . . . . . . . . . . . . 66
5.5.1 Standard 802.11a-type interleaver . . . . . . . . . . . . . . . . . . . . . . . . 66
i5.5.2 Convolutional code performance using standard 802.11a-type interleaver . . . 67
5.5.3 "Folded" interleaver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
5.5.4 Performance comparison for standard and folded interleaver . . . . . . . . . . 71
5.5.5 Interleaving scheme for WiMAX LDPC code (768,384), performance comparison 72
5.6 Preamble waveform design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
5.7 Preamble processing overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
5.8 Frame detection, coarse timing synchronization and CFO estimation . . . . . . . . . . 78
5.9 Channel estimation and equalization . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
5.9.1 Channel estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
5.9.2 Equalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
5.10 Fine time synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
5.11 Tracking of phase and timing and channel re-estimation . . . . . . . . . . . . . . . . . 90
5.11.1 Tracking scheme for narrowband system (WIGWAM demonstrator) . . . . . . 92
5.11.2 Improved tracking scheme for wideband system . . . . . . . . . . . . . . . . . 95
5.12 Receiver performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
5.12.1 Performance of narrowband PHY for HHI channels . . . . . . . . . . . . . . . 99
5.12.2 Synchronization performance for wideband mode . . . . . . . . . . . . . . . . 101
5.12.3 Performance of wideband PHY in static channel . . . . . . . . . . . . . . . . 102
5.12.4 Performance of wideband PHY in residential time-variant NLOS channel . . . 104
6 Baseband processor implementation 107
6.1 Strategy for FPGA-based processor designs . . . . . . . . . . . . . . . . . . . . . . . 107
6.2 Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
6.3 Receiver overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
6.4 Coarse synchronization and CFO estimation block . . . . . . . . . . . . . . . . . . . . 113
6.4.1 Autocorrelator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
6.4.2 Antiphase detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
6.4.3 Clustering logic, main controller and long autocorrelator . . . . . . . . . . . . 116
6.5 Channel estimator and post-FFT timing estimator . . . . . . . . . . . . . . . . . . . . 117
6.6 Pilot machine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
6.7 Data equalizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
6.8 Four-port 256-point FFT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
6.9 Combined de-interleaving and depuncturing . . . . . . . . . . . . . . . . . . . . . . . 126
6.10 Viterbi decoder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
6.11 Digital automatic gain control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
7 Conclusion 139
A Derivation of the phase-noise induced CFO estimation performance 141
iiB Mathematical models for radio channels 144
B.1 Continuous-time channel representation . . . . . . . . . . . . . . . . . . . . . . . . . 144
B.2 Time-variant discrete-time channel representation . . . . . . . . . . . . . . . . . . . . 146
B.3 Static discrete-time channel model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
B.4 Simplified time-variant discrete-time channel representation . . . . . . . . . . . . . . 147
B.5 Characterization of radio channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
C Mathematical basics of orthogonal frequency division multiplexing 151
C.1 Continuous-time signal model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
C.2 OFDM pulse wav