Adaptive Hierarchical Weighted Fair Queuing Scheduling in WiMAX Networks by Waleed K. AL-Ghanem A Dissertation Submitted to the Department of Computer & Electrical Engineering and Computer Science College of Engineering & Computer Science In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Florida Atlantic University Boca Raton, FL August 2014 Copyright by Waleed K. AL-Ghanem 2014 ii Acknowledgements I am indebted to my supervisor Dr. Mohammad Ilyas for giving me an opportunity to work under his supervision and guidance throughout the Ph.D study. His valuable suggestions and ideas have given me great scope and flexibility to work in the best possible way to accomplish my goals in this field. Thanks to my co-advisor Dr. Imad Mahgoub, to my committee members Dr. Borko Furht, and Dr. Mihaela Cardei for their careful analysis, constructive criticism, and supportive commentary. For My Uncle Dr. Abdulhakim M. AL-Ghanem, thanks for your support, encouragement, and always believing in me, and pushing me to achieve greater things. iv Abstract Author: Waleed Khalid AL-Ghanem Title: Adaptive Hierarchical Weighted Fair Queuing Scheduling in WiMAX Networks Institution: Florida Atlantic University Dissertation Advisor’s: Dr. Mohammad Ilyas, and Dr. Imad Mahgoub Degree: Doctor of Philosophy Year: 2014 The growing demand for faster connection to the Internet service and wireless multimedia applications has motivated the development of broadband wireless access technologies in recent years. WiMAX has enabled convergence of mobile and fixed broadband networks through a common wide-area radio-access technology and flexible network architecture. Scheduling is a fundamental component in resource management in WiMAX networks and plays the main role in meeting QoS requirements such as delay, throughput and packet loss for different classes of service. In this dissertation work, the performance of uplink schedulers at the fixed WiMAX MAC layer has been considered, we proposed an Adaptive Hierarchical Weighted Fair Queuing Scheduling algorithm, the new scheduling algorithm adapts to changes in traffic, at the same time; it is able to heuristically enhance the performance of WiMAX network under most circumstances. The heuristic nature of this scheduling algorithm enables the MAC layer to meet the QoS requirements of the users. v The performance of this adaptive WiMAX Uplink algorithm has been evaluated by simulation using MATLAB. Results indicate that the algorithm is efficient in scheduling the Base Stations’ traffic loads, and improves QoS. The utilization of relay stations is studied and simulation results are compared with the case without using relay stations. The results show that the proposed scheduling algorithm improves Quality of Service of WiMAX system. vi Adaptive Hierarchical Weighted Fair Queuing Scheduling in WiMAX Networks List of Tables ..................................................................................................................... xi List of Figures ................................................................................................................... xii CHAPTER 1. Introduction.................................................................................................. 1 1.1. Scheduling Problem Formulation ............................................................................ 3 1.2. Approaches to Scheduling Problems ....................................................................... 4 1.3. Quality of Service .................................................................................................... 5 1.4. Scheduling Algorithms ............................................................................................ 7 1.4.1. Strict-Priority .................................................................................................... 7 1.4.2. Round-Robin ..................................................................................................... 9 1.4.3. Weighted Round Robin (WRR) ...................................................................... 10 1.4.4. Weighted Fair Queuing (WFQ) ...................................................................... 14 1.4.5. Earliest Deadline First (EDF) ......................................................................... 18 1.5. Statement of the Research Problem ....................................................................... 19 1.6. Contributions.......................................................................................................... 20 1.7. Dissertation Outline ............................................................................................... 21 vii CHAPTER 2. Adaptive Hierarchical Weighted Fair Queuing Scheduling Algorithm .... 23 2.1. Traffic Type of Flows ............................................................................................ 23 2.2. Scheduling Algorithm ............................................................................................ 26 2.3. Summary ................................................................................................................ 31 CHAPTER 3. Modeling Traffic ........................................................................................ 32 3.1. Modeling Self-Similar Traffic for Simulation ....................................................... 32 3.2. Traffic Load Generator .......................................................................................... 36 3.3. Traffic Assumptions............................................................................................... 37 3.3.1. Generated Ttraffic ........................................................................................... 39 3.4. Send Receive Model .............................................................................................. 43 3.4.1. Randomizer ..................................................................................................... 43 3.4.2. Convolutional Encoder ................................................................................... 44 3.4.3. Interleaver ....................................................................................................... 45 3.4.4. Modulation ...................................................................................................... 45 3.4.5. Cyclic Prefix ................................................................................................... 45 3.4.6. Viterbi Decoder ............................................................................................... 46 3.5. Channel Model ....................................................................................................... 47 3.5.1. Path Loss ......................................................................................................... 48 3.5.2. Shadowing....................................................................................................... 48 3.5.3. Multipath ......................................................................................................... 49 viii 3.6. Stanford University Interim (SUI) Channel Models .............................................. 49 3.7. Effective Data Rate ................................................................................................ 52 3.7.1. Bit Errors ......................................................................................................... 52 3.7.2. Building Effective Data Rate Computer Based Model ................................... 54 3.7.3. Testing the Effective Data Rate Model ........................................................... 56 CHAPTER 4. Evaluation of Performance ........................................................................ 59 4.1. Assumptions ........................................................................................................... 59 4.2. Quality of Service Aspects ..................................................................................... 62 4.2.1. Throughput ...................................................................................................... 62 4.2.2. Goodput........................................................................................................... 62 4.2.3. Dropped Packets ............................................................................................. 63 4.2.4. Re-Transmission ............................................................................................. 63 4.2.5. Latency ............................................................................................................ 63 4.2.6. Jitter................................................................................................................. 64 4.2.7. Fairness ........................................................................................................... 64 4.3. Configuring Queue Weights .................................................................................. 64 4.3.1. Scenarios ......................................................................................................... 65 4.3.2. Results ............................................................................................................. 65 4.4. Scheduling Algorithm Performance ...................................................................... 71 4.5. Studying the Effect of Traffic Load ....................................................................... 76 ix CHAPTER 5. Algorithm Performance in Multihop Relay Systems................................