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The Study of Multiple Access Techniques in Ultra Wideband THE STUDY OF MULTIPLE ACCESS TECHNIQUES IN ULTRA WIDEBAND IMPULSE RADIO COMMUNICATIONS ADissertation Presented to The Graduate Faculty of The University of Akron In Partial Fulfillment of the Requirements of the Degree Doctor of Philosophy Yuhua Zhao August, 2005 THE STUDY OF MULTIPLE ACCESS TECHNIQUES IN ULTRA WIDEBAND IMPULSE RADIO COMMUNICATIONS Yuhua Zhao Dissertation Approved: Accepted: Advisor Department Chair Dr. Okechukwu C. Ugweje Dr. J. Alexis De Abreu-Garcia Committee Member Dean of the College Dr. John Welch Dr. George K. Haritos Committee Member Dean of the Graduate School Dr. John Durkin Dr. George R. Newkome Committee Member Date Dr. Paul Lam Committee Member Dr. Dale Mugler ii ABSTRACT In this dissertation, the system performance of multiple access schemes in Ultra Wide- band (UWB) communications is evaluated in a multipath and multiuser fading environ- ment. Three multiple access schemes, namely Time Hopping (TH), Direct Sequence (DS) and hybrid Direct Sequence-Time Hopping (DS-TH) are investigated. The TH multiple access has been well studied in Radar communication systems. This research extends the previous studies by applying three pulse modulations techniques, including pulse posi- tion modulation, pulse shift keying and pulse amplitude modulation. The idea of the DS multiple access schemes is also generalized from the well-known Direct Sequence-Code Division Multiple Access (DS-CDMA) cellular systems to UWB radios. It is shown that the DS multiple access has the potential to reach higher data transmission rates and that TH techniques are more resistant to fading. The DS-TH multiple access schemes are proposed by combining the advantages of both TH and DS multiple access schemes. Results show that the DS-TH ultra wideband achieves better system performance while maintaining the required data transmission rate and multiple access capacity. The system performance is illustrated and examined in terms of the signal to noise plus interference ratio, bit error rate and outage probability. iii ACKNOWLEDGMENTS I would like to express my sincere appreciationtomyadvisor,Dr.OkechukwuC. Ugweje, for his invaluable advice, guidance, support and encouragement throughout the duration of this work, without which this work would not have been possible. I am looking forward to maintaining a continued friendship with him. Special thanks go to Dr. Paul C. K. Lam, Associate Dean of the College of Engi- neering, for his help and financial support during my academic career at The University of Akron. He has been somewhat of a father figure to me. It has been a pleasure working under his supervision and his kindness and understanding will be a valuable memory in my life. I wish to express my deep gratitude to other committee members, Dr. John Welch, Dr. Jack Durkin and Dr. Dale Mugler for their careful reading, corrections and helpful discussion during my research. Appreciation is also given to the Department of Electrical and Computer Engineering for the financial support. I want to thank all the faculty, staff members and friends in the department for their assistance, especially Dr. Tom Hartley and Ms. Gay Boden, secretary of the Department of Electrical and Computer Engineering. My true love goes to my parents for their constant encouragement and moral sup- port, which helps me through hard times and several challenges of completing this work. Above all, my love and admiration goes to my husband, Alex Jiaokai Jing, for his love, understanding, support and help. iv TABLE OF CONTENTS Page LISTOFTABLES......................................................... ix LISTOFFIGURES........................................................ x LISTOFACRONYMS..................................................... xiii LISTOFSYMBOLS....................................................... xv CHAPTER I.INTRODUCTION..................................................... 1 1.1Motivation........................................................ 1 1.2ProblemStatement................................................. 3 1.3 Importance and Contribution of Research............................. 6 1.4DissertationOutline................................................ 7 II. UWB COMMUNICATIONS SYSTEM ................................. 8 2.1 DefinitionofUWBSignals.......................................... 8 2.2UWBPulseShapes................................................. 9 2.3PulseModulation.................................................. 12 2.3.1 Pulse Position Modulation . ..................................... 12 2.3.2 Pulse Amplitude Modulation.................................... 13 2.3.3PulseShiftKeying............................................. 14 2.4 Spread Spectrum Techniques . ..................................... 14 v 2.5 Generalized UWB System Model..................................... 17 2.5.1TransmitterModel.............................................. 17 2.5.2ChannelModel................................................. 19 2.5.3ReceiverModel................................................. 21 2.6 System Performance Parameters...................................... 24 2.6.1 Signal-to-Noise plus InterferenceRatio........................... 24 2.6.2BitErrorRate.................................................. 25 2.6.3OutageProbability.............................................. 26 2.7 Diversity Combining Techniques..................................... 26 2.7.1SelectionDiversity.............................................. 27 2.7.2 Maximal Ratio Combining . ...................................... 29 2.7.3 Equal Gain Combining . ................................... 30 2.8Summary.......................................................... 31 III.TIMEHOPPINGUWBMULTIPLEACCESSTECHNIQUES............ 32 3.1Introduction........................................................ 32 3.2 Time Hopping-Pulse Position Modulation............................. 33 3.2.1 Transmitted TH-PPM Ultra Wideband Signals . .................. 33 3.2.2 Received TH-PPM Ultra WidebandSignals........................ 35 3.2.3 Variance of TH-PPM Ultra WidebandSystems..................... 36 3.2.4 Pulse Signal Properties . ...................................... 40 3.2.5 Signal-to-Noise plus Interference Ratio for TH-PPM Systems . 41 3.2.6 Bit Error Rate for TH-PPM Systems.............................. 48 vi 3.2.7 Outage Probability for TH-PPMSystems........................ 57 3.3 Time Hopping-Phase Shift Keying.................................. 61 3.3.1 Transmitted TH-PSK Ultra Wideband Signals . ................ 61 3.3.2 Received TH-PSK Ultra WidebandSignals....................... 62 3.3.3 Variance of TH-PSK Systems . .................................. 63 3.3.4Signal-to-NoiseplusInterferenceRatioforTH-PSKSystems...... 65 3.3.5 Bit Error Rate for TH-PSK Systems............................. 69 3.3.6 Outage Probability for TH-PSKSystems......................... 75 3.4 Time Hopping-Pulse Amplitude Modulation......................... 79 3.5Conclusions....................................................... 79 IV. DIRECT SEQUENCE MULTIPLE ACCESS UWB SYSTEM. ........ 81 4.1 Introduction. ................................................... 81 4.2 DS-PSK Ultra Wideband Signals.................................... 82 4.3 Variance of DS-PSK Ultra WidebandSystems........................ 84 4.4 System Performance for DS-PSK Ultra Wideband Communications . 91 4.4.1 Signal-to-Noise plus InterferenceRatio.......................... 92 4.4.2BitErrorRateforDS-PSKUltraWidebandSystems.............. 96 4.4.3 Outage Probability for DS-PSK Ultra Wideband Systems . 101 4.5Conclusions....................................................... 104 V. DIRECT SEQUENCE-TIME HOPPING MULTIPLE ACCESS . 106 5.1 Introduction. ................................................ 106 5.2DS-THUltraWidebandSignals..................................... 107 vii 5.3 Variance of DS-TH Ultra WidebandSystems......................... 109 5.4 System Performance for DS-TH Ultra Wideband Communications . 114 5.4.1 Signal-to-Noise plus InterferenceRatio........................... 114 5.4.2BitErrorRateforDS-THUltraWidebandSystems................ 119 5.4.3 Outage Probability for DS-TH Ultra Wideband Systems . 124 5.5Conclusions....................................................... 126 VI SUMMARY AND CONCLUSIONS . ............................... 128 6.1SummaryofResults................................................ 128 6.2SummaryofChapters.............................................. 129 6.3 Future Research Suggestions . ...................................... 130 REFERENCES............................................................ 132 APPENDICES. .................................. 139 APPENDIXA.DERIVATIONOFTHEVARIANCEOFNOISE............. 140 APPENDIX B. GAUSS-LAGUERRE INTEGRATION...................... 142 viii LIST OF TABLES Table Page 3.1 Pulse signal parameters for TH-PPM ultra wideband systems. 41 3.2 Pulse signal parameters for TH-PSK ultra wideband systems . 65 4.1 Pulse signal parameters for DS-PSK ultrawidebandsystems........... 91 B.1 16-point Gauss-Laguerre integration................................. 142 ix LIST OF FIGURES Figure Page 1.1 Powerspectraldensitiesofdifferentcommunicationtechniques......... 2 2.1 FCC emission specification for indoor applications.................... 9 2.2 UWB pulses in both time and frequencydomains...................... 10 2.3 Illustration of pulse modulation techniques............................ 13 2.4 Classification of different spread spectrum systems . .............. 15 2.5 BlockdiagramofUWBcommunicationsystemmodel................
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