Simulation Platform for the Planning and Design of Networks Carrying VoIP Traffic by Abdel Hernandez Rabassa B.Eng. (2000) A Thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Masters of Applied Science in Electrical Engineering Ottawa-Carleton Institute for Electrical and Computer Engineering Department of Systems and Computer Engineering Carleton University Ottawa, Ontario, Canada, K1S 5B6 May, 2010 The undersigned recommend to the Faculty of Graduate Studies and ii Research acceptance of the thesis Simulation Platform for the Planning and Design of Networks Carrying VoIP Traffic Submitted by Abdel Hernandez Rabassa B.Eng. In partial fulfillment of the requirements for the degree of Masters of Applied Science --------------------------------------------------------------------------- Chair, Dr. H.M. Schwartz, Department of Systems and Computer Engineering --------------------------------------------------------------------------- Thesis Co-supervisor, Dr. Marc St-Hilaire --------------------------------------------------------------------------- Thesis Co-supervisor, Dr. Chung-Horng Lung Carleton University May 2010 iii Abstract In order to overcome the known challenges (i.e., latency, jitter, packet loss, and etc.) of transmitting multimedia traffic over a packet switched network, careful network planning needs to take pace. Existing simulation platforms, particularly for Voice over IP (VoIP) simulations, have available a limited selections of speech encoding algorithms. The primary objective of this thesis is the creation of a tool aimed at supporting the planning and design phases of packet switched networks carrying voice traffic while considering realistic and current network conditions and simulation features. More specifically, this thesis focuses on the creation of a speech background traffic generation models with the purpose of generating traffic that follows the behaviour of a number of speech encoding algorithms. Also, a model to integrate real speech to the VoIP simulation is offered. Lastly, objective and subjective speech quality assessment methodologies are implemented. iv Acknowledgements To my wife Rachel Jane for giving me the initial impulse and courage to face this challenge, and for the support throughout, thank you very much. I am very grateful to my lovely kids, Caleb B. and Gaby Lou for having decided to arrive to this world within the frame of this degree. They have made this journey interesting and lively and diverse. I am grateful to my thesis supervisors, Professors Marc St-Hilaire, Chung-Horng Lung for their support and advice. Also, I am grateful to Professor Ioannis Lambadaris for his invaluable expert advice. To my parents, for having always being there, because you are now here, thank you very much. I am grateful to my friend Victor, for being the Toronto office of my simulations and for listening. To Frank, for all the moments together, I am grateful. Finally, I acknowledge the financial support from Mathematics of Information Technology and Complex Systems (MITACS) and Cistel Technology Inc. towards the completion of this degree. v Table of Contents Abstract ............................................................................................................................. iii Acknowledgements .......................................................................................................... iv Table of Contents .............................................................................................................. v List of Figures ................................................................................................................. viii List of Tables ..................................................................................................................... x List of Acronyms .............................................................................................................. xi Chapter 1 Introduction..................................................................................................... 1 1.1 Problem Statement .................................................................................................... 3 1.2 Research Objectives .................................................................................................. 6 1.3 Main Contributions ................................................................................................... 7 1.4 Thesis outline ............................................................................................................ 7 Chapter 2 Related Works ................................................................................................. 9 2.1 Study of speech encoding algorithms and feasibility of integration to a simulation platform ......................................................................................................................... 10 2.1.1 General characteristics of audio compression codecs ................................................... 11 2.1.2 Fixed data rate speech encoder algorithms ................................................................... 12 2.1.3 Variable data rate speech encoder algorithms ............................................................... 14 2.1.4 Study of the feasibility of integrating encoding algorithms to a simulation platform .. 19 2.2 Study of Speech Quality Assessment Models ......................................................... 22 2.2.1 Understanding VoIP Quality Assessment Models ........................................................ 23 2.2.2 Description of relevant speech quality assessment models for VoIP systems .............. 27 vi 2.2.3 Selection of the speech quality assessment models to integrate to the simulation platform .................................................................................................................................. 37 Chapter 3 VoIP Simulation Models and OPNET Implementations .......................... 40 3.1 Speech background traffic generation ..................................................................... 40 3.1.1 Available encoding algorithms and parameter calculations .......................................... 41 3.1.2 Analysis of the number of speech frames per packet attribute ..................................... 51 3.1.3 Computation of the voice payload size ......................................................................... 54 3.1.4 Background traffic scalability method .......................................................................... 56 3.1.5 General operation of the simulation of speech background traffic generation in OPNET ................................................................................................................................... 57 3.2 Simulation of real speech traffic in OPNET ........................................................... 61 3.2.1 Encoding algorithms used in real speech simulation and licensing details ................... 62 3.2.2 Playout buffer (De-jitter buffer) .................................................................................... 63 3.2.3 General operation of the simulation of real speech traffic generation in OPNET ........ 64 3.2.4 Objective speech quality assessment ............................................................................ 70 3.2.5 Subjective speech quality assessment ........................................................................... 74 Chapter 4 Model Validation and Simulation Results Analysis .................................. 78 4.1 Validation of simulation models ............................................................................. 78 4.1.1 Validation of traffic generation models for fixed data rate encoding algorithms ......... 79 4.1.2 Validation of traffic generation model for AMR-NB encoding algorithm ................... 82 4.1.3 Validation of traffic generation model for Speex encoding algorithm ......................... 85 4.2 Codec packet loss concealment evaluation and playout buffer optimization ......... 87 4.3 Simulation of a real life scenario............................................................................. 92 4.3.1 Deploying VoIP within a single office ......................................................................... 92 vii 4.3.2 Deploying VoIP across several branch offices ........................................................... 100 4.3.3 Deploying VoIP across several branch offices. Solutions to low MOS and high network load problems ......................................................................................................... 103 4.3.4 Deploying VoIP across several branch offices. Performance analysis using real Internet traffic trace .............................................................................................................. 110 Chapter 5 Conclusions and Future Work .................................................................. 115 5.1 Summary of thesis ................................................................................................. 115 5.2 Summary of results................................................................................................ 115 5.3 Suggestions for future research ............................................................................. 116 References ...................................................................................................................... 117 Appendix A New Nodes Added to OPNET................................................................