Radio Resource Management WCDMA Systems

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<p>ABSTRACTSUBRAMANIAM, KAMALA. Radio Resource Management in UMTS-WCDMA Systems. (Under the direction of Professor Arne A. Nilsson). Universal Mobile Telecommunications System (UMTS) is a Third Generation (3G) cellular technology representing an evolution of a heterogenous mix of services and increased data speeds from todays second generation mobile networks. UMTS uses Wideband Code Division Multiple Access (WCDMA) as its radio air interface. The implementation of WCDMA is a technical challenge because of its complexity and versatility. Billions of dollars have been spent procuring these air interfaces. To exploit the exibility of the air interface, development of Radio Resource Management (RRM) schemes are imperative. RRM is comprised of power control, handover control, load control and resource allocation algorithms. These ensure optimum network coverage, maximize the system throughput and , guarantee Quality of Service (QoS) requirements to users having dierent requirements. This research investigates mainly the resource allocation and power control algorithms with which the load control and handover control are intertwined. The state of the art is studied and their pros and cons are discussed, which lays the foundation for the need for more ecient RRM schemes that are eventually presented in this research. The two main schemes considered here are:1)Adaptive Call Admission Control (ACAC) scheme for resource allocation where the system is mathematically modeled as a multi-rate system with priority. Further, a tier based analytical model pertaining to the hierarchical hexagonal cell structure is analyzed and mobility is given importance. 2) Adaptive Uplink Power Control (AUPC) scheme for power control is analyzed where Monte Carlo simulations are used to ne-tune WCDMA link budget parameters. Finally, Location Update (LU) procedures in cellular networks using Bloom Filters is studied where bandwidth gain is given importance. Various performance metrics are observed and two key metrics are given the most importance: the Call Blocking and Call Dropping probabilities. Simulation results are compared to the existing schemes and further strengthened by comparing them to analytical results which validate the entirety of this research.</p> <p>RADIO RESOURCE MANAGEMENT IN UMTS-WCDMA SYSTEMS by Kamala Subramaniam A dissertation submitted to the Graduate Faculty of North Carolina State University in partial satisfaction of the requirements for the Degree of Doctor of Philosophy</p> <p>Computer Engineering Raleigh, NC 2005</p> <p>Approved By:</p> <p>Dr. George Rouskas</p> <p>Dr. Wenye Wang</p> <p>Dr. Arne A. Nilsson Chair of Advisory Committee</p> <p>Dr. Ioannis Viniotis</p> <p>ii</p> <p>For Piyush......whose existence is testimony to lifes goodness</p> <p>iii Biography Kamala Subramaniam was born to Gauri (mother) and Mani (father) in India on seventeenth February, 1977. She spent the rst ten years of her life in Mumbai (formerly Bombay), the nancial capital of India and the next twelve in Bangalore, the silicon valley of India. After her high school, she joined Vishweshwariah Techological University for her Bachelors in Electronics and Instrumentation Engineering where she graduated summa cum laude in 1998. She then enrolled for a Masters at North Carolina State University in the department of Electrical and Computer Engineering majoring in Computer Networking. What she learnt here coupled with the height of the telecom bubble, whet her curiosity and sealed the deal with the world of telecommunications. She went to work at Nortel Networks (NTL) at Research Triangle Park as a VoIP software developer for a year. Working with the nest people in the area, she realized the need to hone her skills and joined the Doctoral program at North Carolina State University in the same department. Also, wireless networking was taking o in a huge way. The next four years, her most fruitful professionally, she developed algorithms for cellular networks. She also interned with Catapult Communications (CATT) a third generation solutions provider. In the interim, she was the President of the Electrical and Computer Engineering Graduate Student Association (ECEGSA) where she introduced the seminar series, semester picnics and more faculty-student interaction socials. She also served as the Vice-President of the Indian Graduate Students Association. She was honored to be accepted as a member of Eta Kappa Nu, the Electrical Engineering Honors Society and Society of Women Engineers. She hopes to continue to work in research areas involving cellular networks, performance modeling, queuing theory and random processes.</p> <p>iv</p> <p>AcknowledgementsThis dissertation would not have been possible but for Dr. Arne Nilsson. I am grateful to him for being a mentor rst and then an advisor. He has helped me rise for every fall I have had both professionally and personally. The vast knowledge he granted me will carry me through the rest of this life with much panache. I am grateful to Dr. Trussell (the Director of Graduate of Programs) and his ecient department, for helping me with the day to day saga of being an international graduate student. I thank Dr. Viniotis, Dr. Rouskas and Dr. Wang for their guidance and I am honored to have them on my committee. I am grateful to my mother, Gauri, for making me the ghter I am today and to my sister, Priya, for her unwavering condence in and love for me. This would be incomplete without my friends. Ramki, who helped me with my last minute, late night coding issues and his unconditional friendship. Reshmi and Sreekanth, who gave me tremendous moral support. And Piyush, for always being there.</p> <p>v</p> <p>ContentsList of Figures List of Tables 1 Introduction 1.1 Problem Statement . . . . . . . . . . 1.2 Specic Contribution . . . . . . . . . 1.3 Background and Motivation . . . . . 1.4 Research Questions and Limitations viii x 1 2 3 5 6 9 9 12 14 16 18 20 20 21 22 22 23 24 25 27 31 32 32 34 35</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>2 Background 2.1 Architecture of the UMTS system . . . . . . . . . . . 2.2 Wideband Code Division Multiple Access (WCDMA) 2.3 UMTS QoS Bearer Classes . . . . . . . . . . . . . . . 2.4 Rationale behind CAC schemes . . . . . . . . . . . . . 2.5 Terminology used in CAC schemes . . . . . . . . . . . 3 State of the Art 3.1 Before 3G and WCDMA . . . . . . . . . . . . . . 3.2 On the capacity of CDMA and WCDMA systems 3.3 On WCDMA and UMTS . . . . . . . . . . . . . 3.3.1 Dimitriou et. al. . . . . . . . . . . . . . . 3.3.2 Capone et. al. . . . . . . . . . . . . . . . 3.3.3 Stol et. al. . . . . . . . . . . . . . . . . . 3.3.4 Victor O.K. Li et. al . . . . . . . . . . . . 3.3.5 Schultz et. al. . . . . . . . . . . . . . . . .</p> <p>. . . . .</p> <p>. . . . .</p> <p>. . . . .</p> <p>. . . . .</p> <p>. . . . .</p> <p>. . . . .</p> <p>. . . . .</p> <p>. . . . .</p> <p>. . . . .</p> <p>. . . . .</p> <p>. . . . .</p> <p>. . . . .</p> <p>. . . . . . . .</p> <p>. . . . . . . .</p> <p>. . . . . . . .</p> <p>. . . . . . . .</p> <p>. . . . . . . .</p> <p>. . . . . . . .</p> <p>. . . . . . . .</p> <p>. . . . . . . .</p> <p>. . . . . . . .</p> <p>. . . . . . . .</p> <p>. . . . . . . .</p> <p>. . . . . . . .</p> <p>. . . . . . . .</p> <p>. . . . . . . .</p> <p>. . . . . . . .</p> <p>4 Methodology and Model Design 4.1 Wideband Power Based Admission Control Scheme 4.1.1 Uplink Criterion . . . . . . . . . . . . . . . 4.1.2 Downlink Criterion . . . . . . . . . . . . . . 4.2 Throughput Based Admission Control Scheme . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>. . . .</p> <p>vi 4.2.1 Uplink Criterion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.2 Downlink Criterion . . . . . . . . . . . . . . . . . . . . . . . . . . . . Proposed Adaptive Call Admission Control Scheme . . . . . . . . . . . . . . 35 35 36 38 38 40 40 43 43 43 44 45 45 48 49 50 51 53 53 54 57 59 59 60 61 63 64 64 65 66 67 67 71 72 74 74 75 75 76 77 77</p> <p>4.3</p> <p>5 Simulation Modeling 5.1 Node-B Simulation Parameters . . . . . . . . . . . . . . . . . . . . . . . . 5.2 Radio Network Controller Call Admission Control Simulation Parameters 5.3 WCDMA Link Budget . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.4 Voice Users Simulation Parameters . . . . . . . . . . . . . . . . . . . . . . 5.5 Video Users Simulation Parameters . . . . . . . . . . . . . . . . . . . . . 5.6 FTP Users Simulation Parameters . . . . . . . . . . . . . . . . . . . . . . 5.7 Mobility Simulation Parameters . . . . . . . . . . . . . . . . . . . . . . . . 6 Analytical Modeling 6.1 Multi-rate Erlang-B Computation . . . . . . . . . . . . . . . . . . . 6.2 Single rate prioritized system using conservation law . . . . . . . . . 6.3 Proposed Analytical Models . . . . . . . . . . . . . . . . . . . . . . . 6.3.1 Model 1: Multi-rate Erlang-B with priority . . . . . . . . . . 6.3.2 Model 2: Multi-rate Erlang-B with priority and tier analysis 7 Power Control 7.1 Introduction . . . . . . . . . . . . . . . . . 7.2 Problem Description . . . . . . . . . . . . 7.3 Previous Work . . . . . . . . . . . . . . . 7.4 Step Size Evaluation of Eb /No . . . . . . . 7.4.1 In Outer Loop Power Control . . . 7.4.2 In Adaptive Uplink Power Control 7.5 Spectral Eciency of a WCDMA cell . . . 7.6 Adaptive Calculation of Pj . . . . . . . . 7.7 Simulation Model . . . . . . . . . . . . . . 7.8 Summary . . . . . . . . . . . . . . . . . .</p> <p>. . . . . . .</p> <p>. . . . .</p> <p>. . . . .</p> <p>. . . . .</p> <p>. . . . .</p> <p>. . . . . . . . . .</p> <p>. . . . . . . . . .</p> <p>. . . . . . . . . .</p> <p>. . . . . . . . . .</p> <p>. . . . . . . . . .</p> <p>. . . . . . . . . .</p> <p>. . . . . . . . . .</p> <p>. . . . . . . . . .</p> <p>. . . . . . . . . .</p> <p>. . . . . . . . . .</p> <p>. . . . . . . . . .</p> <p>. . . . . . . . . .</p> <p>. . . . . . . . . .</p> <p>. . . . . . . . . .</p> <p>. . . . . . . . . .</p> <p>. . . . . . . . . .</p> <p>. . . . . . . . . .</p> <p>. . . . . . . . . .</p> <p>. . . . . . . . . .</p> <p>8 Results and Discussions 8.1 Call Admission Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1.1 Single Run Scenario . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1.2 Condence Intervals . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1.3 Comparison of analytical and simulation results . . . . . . . . . . . . 8.1.4 Comparison of Simulation and Analytical Results with Tier Analysis 8.2 Power Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.1 Comparison of OLPC and AUPC with respect to Average (Eb /No )j 8.2.2 Comparison of OLPC and AUPC with respect to Total U L . . . . 8.2.3 Comparison of OLPC and AUPC with respect to Noise Rise . . . . 8.2.4 Comparison of OLPC and AUPC with respect to (Eb /No )j . . . . . 8.2.5 Comparison of OLPC and AUPC with respect to Lj . . . . . . . . . 8.2.6 Comparison of OLPC and AUPC with respect to Transmit Power Pj</p> <p>vii 8.2.7 Comparison of Voice and Data Blocking Probabilities with and without Power Control . . . . . . . . . . . . . . . . . . . . . . . . . . . .</p> <p>79 80 80 81 81 83 84 86 86 88 90 90 91 91 92 93 96 97 100 108</p> <p>9 Location Updates of Cellular Networks Using Bloom Filters 9.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1.1 Bloom Filters . . . . . . . . . . . . . . . . . . . . . . . . 9.1.2 Variations of Bloom Filters . . . . . . . . . . . . . . . . 9.1.3 Applications of Bloom Filters . . . . . . . . . . . . . . . 9.2 Location Updates and Bloom Filters . . . . . . . . . . . . . . . 9.3 Analytical Modeling . . . . . . . . . . . . . . . . . . . . . . . . 9.3.1 Optimization of Hash Functions (OBF) . . . . . . . . . 9.3.2 Cumulative Bloom Filters . . . . . . . . . . . . . . . . . 9.3.3 Performance Metrics . . . . . . . . . . . . . . . . . . . . 9.4 Simulation Modeling . . . . . . . . . . . . . . . . . . . . . . . . 9.5 Results and Discussions . . . . . . . . . . . . . . . . . . . . . . 9.5.1 Without Optimization . . . . . . . . . . . . . . . . . . . 9.5.2 With Optimization . . . . . . . . . . . . . . . . . . . . . 9.5.3 With Optimization and Cumulative Bloom Filters . . . 9.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Conclusions and Future Work Bibliography A Acronyms</p> <p>. . . . . . . . . . . . . . .</p> <p>. . . . . . . . . . . . . . .</p> <p>. . . . . . . . . . . . . . .</p> <p>. . . . . . . . . . . . . . .</p> <p>. . . . . . . . . . . . . . .</p> <p>. . . . . . . . . . . . . . .</p> <p>. . . . . . . . . . . . . . .</p> <p>viii</p> <p>List of Figures1.1 2.1 4.1 5.1 6.1 6.2 6.3 7.1 7.2 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 8.10 8.11 8.12 8.13 Research Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . UMTS Network Architecure . . . . . . . . . . . . . . . . . . . . . . . . . . . Shows Load curve and the, due to a new call, increase in Interference . . . . Simulation Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Multi-rate Erlang-B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Part 1: Analytical Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . Part 2: Analytical Modeling with tiers . . . . . . . . . . . . . . . . . . . . Near Far Eect in WCDMA . . . . . . . . . . . . . . . . . . . . . . . . . . . Outer Loop Power Control in WCDMA . . . . . . . . . . . . . . . . . . . . Comparison of Data, Voice and Total Blocking Probabilities of 3 schemes . Comparison of Data, Voice and Total Blocking Probabilities of 3 schemes . Comparison of Data, Voice and Total Dropping Probabilities of 3 schemes . Comparison of Analytical and Simulation Results . . . . . . . . . . . . . . . Comparison of Data Blocking with and without Tier Analysis . . . . . . . . Comparison of Voice Blocking with and without Tier Analysis . . . . . . . . OLPC and AUPC with respect to Average (Eb /No )j . . . . . . . . . . . . . OLPC and AUPC with respect to Total U L . . . . . . . . . . . . . . . . . . OLPC and AUPC with respect to Noise Rise . . . . . . . . . . . . . . . . . OLPC and AUPC with respect to (Eb /No )j . . . . . . . . . . . . . . . . . . OLPC and AUPC with respect to Lj . . . . . . . . . . . . . . . . . . . . . . OLPC and AUPC with respect to Pj . . . . . . . . . . . . . . . . . . . . . Comparison of Voice and Data Blocking Probabilities with and without Power Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Location Request and Location Update . . . . . . . . . . . . . . . . . . . . Optimization of Bloom Filter . . . . . . . . . . . . . . . . . . . . . . . . . . Cumulative Bloom Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 10 32 39 46 50 52 55 57 68 70 70 71 73 73 74 75 76 77 78 78 79 85 87 90</p> <p>9.1 9.2 9.3</p> <p>ix 9.4 9.5 9.6 9.7 9.8 9.9 False Positives without Optimization . . . . . . Gain without Optimization . . . . . . . . . . . . False Positives without Optimization . . . . . . Comparison of Ana...</p>