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EVCCM: An Efficient VOIP Congestion Control Mechanism

EVCCM: An Efficient VOIP Congestion Control Mechanism. Presenter: Ming Cao, Hadi Otrok, Benwen Zhu, Noman Mohammed, Prabir Bhattacharya Computer Security Laboratory Concordia Institute for Information Systems Engineering(CIISE) Concordia university Montreal, QC, Canada

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EVCCM: An Efficient VOIP Congestion Control Mechanism

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  1. EVCCM: An Efficient VOIP Congestion Control Mechanism Presenter: Ming Cao, Hadi Otrok, Benwen Zhu, Noman Mohammed, Prabir Bhattacharya Computer Security Laboratory Concordia Institute for Information Systems Engineering(CIISE) Concordia university Montreal, QC, Canada (min_ca, h_otrok, be_zh, no_moham, prabir)@ciise.concordia.ca

  2. Agenda • VOIP Introduction • What VOIP Clients Need? • What Service Providers Need? • Mechanism Design • Our Model • Our Algorithm and Example • Simulation Results and Future Work

  3. Acknowledgement I would like to take this opportunity to express our sincere gratitude to Professor Prabir Bhattacharya and Mr. Hadi Otrok for the subject of game theory. We special thanks for your time and guidance. We had a lot of fun in doing this project.

  4. What is Voice Over Internet Protocol 1. A protocol optimized for the transmission of voice through the Internet or other packet switched networks. 2. By 1973, voice was being transmitted over the early Internet 3. The ability to transmit more than one telephone call over the same broadband connection 4. Conference calling, call forwarding, automatic redial, and caller ID 5. Location independence 6. Integration with other services available over the Internet 7. video conversation, message or data file exchange in parallel with the conversation, audio conferencing Figure quote from wikipedia

  5. VOIP Web Service Based Application

  6. VOIP Challenges • Network Congestion • Denial of Service • Packet Loss • Available Bandwidth • Reliability • Security • Echo

  7. VOIP Congestion Problem

  8. What VOIP Clients Need? • Connect to the services • Availability • Reliability • Quality of Service • Reasonable Price • Security • Confidentiality

  9. What Service Providers Need? • Fair Bandwidth Usage • Availability • Security • Quality of Service • Reputation • User Participation • Mechanism to Control the Traffic

  10. Challenges of Our Model • How to motivate selfish client to participate ? • Incentive (Money Back) • What the clients should reveal? • Cost-of-Analysis • How the incentive should be designed such that truth telling is the dominant ? • Mechanism design

  11. What is Mechanism Design? • Mechanism Design is the subfield of game theory. • It uses game theory tools to achieve desired goal. • The main deference between game theory and mechanism design is the following: • Game theory can be used to study what could happen when independent players act selfishly/maliciously. • Mechanism design allows a game designer to define rules in terms of the Provider Object Function(POF) such that players will play according to these rules.

  12. Mechanism Design • Assume that participants are rational: • Has a set of strategies • Have a well defined valuation function over the possible outcomes • Will always act in a way that maximizes their utility • We as designers wish to optimize some common aggregated goal. • It considers how to implement good system-wide solutions to problems that involve multiple self-interested agents with private information.

  13. Incentive Compatible Mechanism • A mechanism determines as output and also charges payments from the participants. • Utility = Value (outcome)- payment Example: In an auction for a single-item, the outcome defines the allocation, and the payment for the winner. Assuming that agent i has value vi = $10 for the item, then its utility for an outcome is, ui = vi - p = 10 - p, and the agent has positive utility for the outcome so long as p < $10 • A mechanism is incentive compatible (=Truthful=strategy proof) if payments provide incentive to all participants to always truthfully report all private information.

  14. Mechanism Design θ1 θn . . . Player 1 Player n v1 (θi) vn (θi) p1 pn Mechanism computes payment and outcome The Provider Object Function • Mechanism designs the payment such that truth telling is the dominant strategy. This is done by giving the nodes a fixed payment independent of the node’s declaration. 14

  15. Summary • The mechanism asks users to report their private information. • Based on the information, mechanism computes an output and a payment which is strategy proof. • The goal is to design a strategy proof mechanism where each player selects the strategy truthfully to maximize its utility. • Knowing that, there is no reason for users to report their true types!

  16. Our Contributions • Solve the congestion issue in a fair and effective way by allowing users input their best strategies. Server selects users based on the users’ strategies to allocate the resource to the qualified candidates. • Improve the VOIP system performance using a check method, to allow the remaining available resource allocated to the second best users so that the system can maximize the active online candidates. • We allow users to place their strategies according to their selfish reasons which maximize the users’ benefits. • Server selects users based on the users’ cost of analysis function which maximizes the users’ benefits. • Our payment methods based on the VCG mechanism encourages users to participate in the game and increase their loyalty to the service providers.

  17. Mechanism Design Model • User Model <K, Si, Ui > • K is a finite set of K users • Each player i K has a non empty finite set of strategies(Si) • Each player i K has a utility function Ui Ui(Si) = Ci(Si, o) − Paymenti • Server Model Provider Objective Function

  18. VOIP Bandwidth and QoS model • Total packet size = • (L2 header: MP or FRF.12 or Ethernet)+ (IP/UDP/RTP header) + (voice payload size) • PPS(Packets Per Second) = • (codec bit rate) / (voice payload size) • Bandwidth = total packet size * PPS

  19. International Telecommunication Union(ITU) ITU-T Recommendation (User Strategy 1) ITU E-Model

  20. User Strategy • Price Unit they are willing to pay Quality

  21. Our Payment Function

  22. Our Algorithm

  23. Our Example

  24. Simulation Results(1)

  25. Simulation Results(11)

  26. Simulation Results(1I1)

  27. Future Work • Develop a multiple service providers model • Use data mining technique to helps users to determine the price and quality with multiple service providers

  28. Thank you !

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