1. Dr. Nawaporn Wisitpongphan

2. What do you need in order to conduct a PhD Research? A lot of reading in order to Find a PhD thesis topic Find out what other have been done/doing Find out techniques which could be used in your thesis Good Problem formulation (well-begun is half-done) Good techniques/tools Data Collection & analysis Good Results Analysis Good Presentation *** (Journal Papers!!!) Self-Discipline & Self-Learning Motivation

3. What will we study in this class? Different types of Research Theoretical Study Simulation Study Empirical Study Some techniques about Data collections Experimental set up Data Analysis tools Presentation Collaborative Learning. Learning by sharing. Nobody knows everything!!!

4. Goal of this class Students obtain research skills necessary to conduct PhD-level research Or better… Students obtains techniques that can be used to conduct their own research

5. WeekTopicsRemarks 1 (Nov 17) Course Introduction + Research Topic FindingClass Activity 2 (Nov 24) Students’ Presentation + Literature Review Mini Research Project (Introduction) Presentation 3 (Dec 1) Writing Technical Paper 4 (Dec 8) Reading Assignment (Data Clustering) No Class 5 (Dec 15) Data Clustering Techniques (Discussion) 6 (Dec 22) (Project Proposal ) No Class 7 (Dec 29) Take Home Exam (Writing Literature Review) No Class 8 (Jan 5) Literature Review Presentation (Exam Due) Presentation/HW#1 9 (Jan 12) กีฬามหาวิทยาลัย No Class 10 (Jan 19) กีฬามหาวิทยาลัย HW#1 Due No Class 11 (Jan 26) Advanced Research Techniques (Optimization, Regression, Goodness of Fit, etc.) HW#2 12 (Feb 2) Advanced Research Techniques (Part II) HW#2 Due 13 (Feb 9) Queuing Theory HW#3 14 (Feb 16) Invited Talk (TBA) HW#3 Due 15 (Feb 23) Project Presentation Presentation 16 (Mar 2)Final Exam Paper Due

6. Class Info: References Grading Criteria Probability, Random Variables and Stochastic Processes by Athanasios Papoulis Queuing Systems: Vol 1 by Leonard Kleinrock Homework 30% Midterm 15% ResearchPresentation 10% Written Paper 15% Final Exam 30%

7. Class Project Individual Research You will get to Analyze Huge amount of Data collected by NECTEC or Dek-D.com Think about the research goal: What can you do with this data? What kind of information will be useful? Generate some results Write a paper about it : 5-6 page double column Present it in the class

8. Class Format Class Lecture: 1.5-2 hrs Research Advising: 1-1.5 hr after the lecture Class Presentation: 3 hrs Group HW presentation: 0.5 hr

9. Assignment for next week Present your past research work 1. Motivation & Goal 2. Data Collection Technique 3. Tools for Analyzing Data 4. Your Potential PhD Topic

10. Example Title: Analysis of TCP and self-similarity of network traffic. Motivation: Internet traffic is not Poisson!!! It’s heavy-tailed. Data Collection Tool OPNET simulator Statistical/Analytical Tool Variance-Time plot Hurst Parameter

11. Self-Similarity in Traffic Measurement

12. Self-Similarity: Proper Definition A stochastic process X(t) is statistically self-similar with parameter H (0.5  H  1) if for any real a > 0, the process a -H X(at) has the same statistical properties as X(t) This relationship may be expressed by the following conditions: Degree of self-similarity: Hurst parameter (H) or self-similarity parameter is a measure of the persistence of a statistical phenomenon & is a measure of the long-range dependence of the stochastic process H = 0.5  Absence of self-similarity H = 1.0  Greatest degree of persistence or long-range dependence

13. The variance of the sample decreases more slowly than the reciprocal of the sample size For most processes, the variance of a sample diminishes quite rapidly as the sample size is increased, and stabilizes soon For self-similar processes, the variance decreases very slowly, even when the sample size grows quite large Slowly Decaying Variance

14. Mathematically Speaking The m-average process of a discrete-time stationary parent process X 1, X 2,X n, … is The variance is defined as The variances of the aggregated process X(m) decrease linearly for large m Hurst parameter,

15. Methods of showing Self-Similarity H=0.5 H=1 Estimate H  0.8

16. The ‘‘variance-time plot” is one means to test for the slowly decaying variance property Plots the variance of the sample versus the sample size, on a log-log plot For most processes, the result is a straight line with slope -1 For self-similar, the line is much flatter Variance-Time plot is obtained by plotting log(Var[X (m) ] )against log(m) where m is typically equal to 1 ms, 10 ms, 100 ms, 1 s, 100 s, … Variance-Time Plot

17. Variance m Variance of sample on a logarithmic scale 0.0001 0.001 10.0 0.01 100.0

18. Variance-Time Plot Variance m Sample size m on a logarithmic scale 11010010 4567

19. Variance-Time Plot Variance m Slope = -1 for most processes

20. Variance-Time Plot Variance m Slope flatter than -1 for self-similar process

21. Example of Variance-Time Plots

22. Data Collection Techniques Collect throughput at the Network Bottleneck Collect the throughput every 10 ms from OPNET Modeler Use MATLAB to process data, e.g., Construct aggregated process, Find variance of aggregated process, plot V-T graph

23. Reference N. Wisitpongphan and J. M. Peha, “Effect of TCP on Self- Similarity of Network Traffic,” Proceedings of 12th IEEE International Conference on Computer Communications and Networks (ICCCN), Dallas, USA,Oct. 2003Effect of TCP on Self- Similarity of Network Traffic

24. STEP 1:How to find Research Ideas Reading other papers (Lots of them) and write a summary which answers some of these questions: From where did the author seem to draw the ideas? What exactly was accomplished by this piece of work? How does it seem to relate to other work in the field? What would be the reasonable next step to build upon this work? What ideas from related fields might be brought to bear upon this subject? Exposing yourself to research Make a weekly effort to read at least the abstracts from good journals in your field. Read 1-2 papers in detail. Attend a research seminar. Directed Study Should you find the thesis advisor first or thesis topic first? Develop a thesis topic with your advisor using independent study approach.

25. Rule of Thumb Avoid spending all your time doing literature review Good research topic typically aims to solve a certain problem (not EVERY PROBLEM) so.. Be clear on what your problem/motivation is Make legitimate assumptions on certain unknowns Be practical and realistic Research = Work done by STUDENT not advisor “Student should know more than an advisor on the topic” Do not wait for an advisor to tell you what to do, advisor’s job is to give student a feedback.

26. How to select a paper to read? First, find the major conferences in your field. Find the conference program List the conference track Look for a keyword e.g., name of the technique, name of the problem, area of the study (typically listed in the title, abstract, or keyword of the paper) For example: VLDB 2012 http://www.vldb2012.org/general- information/advance-program/