1. Scenarios and System Dynamics of Mobile Peer-to-Peer Content Distribution Juuso Karikoski 23.03.2009

2. Slide 2 TKK Helsinki University of Technology Department of Communications and Networking Outline Research questions Scope of the research Research methods Scenarios System Dynamics Discussion

3. Slide 3 TKK Helsinki University of Technology Department of Communications and Networking Research questions 1. What are the most important scenarios for mobile peer-to-peer (MP2P) content distribution? 2. How to turn the scenarios into relevant system dynamic models?

4. Slide 4 TKK Helsinki University of Technology Department of Communications and Networking Scope of the research (1/2) MP2P content distribution in the Finnish mobile industry Time span 2009-2013 Mobile devices –personal portable laptop computers –personal portable pocket-size computing devices –with cellular / wireless connections

5. Slide 5 TKK Helsinki University of Technology Department of Communications and Networking Scope of the research (2/2) P2P (Androutsellis-Theotokis & Spinellis, 2004). –distributed systems –interconnected self-organizing nodes –purpose to share resources –adapting to failures –accommodating transient populations –maintaining connectivity and performance –no support of a global centralized authority needed

6. Slide 6 TKK Helsinki University of Technology Department of Communications and Networking Research methods Scenario analysis –Schoemaker’s method –Brainstorming Expert session Layman session System dynamics –Vensim PLE software

7. Slide 7 TKK Helsinki University of Technology Department of Communications and Networking Scenarios Decision variable: value of MP2P content distribution services for the end users (Value = End users * Available content) Assumptions: –Battery capacity remains a bottle neck –Network capacity adequate –Regulatory intervention minimal

8. Slide 8 TKK Helsinki University of Technology Department of Communications and Networking Basics of system dynamics (Sterman, 2000) Causal loop diagrams: Stocks and flows:

9. Slide 9 TKK Helsinki University of Technology Department of Communications and Networking Some model assumptions Only file sharing Content only resource distributed No third-party content providers No connection to fixed P2P networks Free Riding ratio increases with group size (Isaac and Walker, 1988) Users unaware of Free Riding Users cannot readopt the technology

10. Slide 10 TKK Helsinki University of Technology Department of Communications and Networking Conceptual model

11. Slide 11 TKK Helsinki University of Technology Department of Communications and Networking

12. Slide 12 TKK Helsinki University of Technology Department of Communications and Networking Discussion A rough simplification of the real world Models the dynamic behavior of the system Abstract variables hard to model quantitatively Subjective assumptions Models constant development Modeler’s skills limited A starting point for further SD modeling

13. Slide 13 TKK Helsinki University of Technology Department of Communications and Networking References Androutsellis-Theotokis, S. and Spinellis, D., 2004. A Survey of Peer-to-Peer Content Distribution Technologies. ACM Computing Surveys, 36(4), pp. 335-371. Isaac, R.M. and Walker, J.M., 1988. Group Size Effects in Public Goods Provision: The Voluntary Contributions Mechanism. The Quarterly Journal of Economics, 103(1), pp. 180-199. Sterman, J. D., 2000. Business Dynamics: Systems Thinking and Modeling for a Complex World. The McGraw-Hill Companies, Inc.