1. Vaggelis G. Douros douros@aueb.gr Applications of Game Theory for Radio Resource Management in Wireless Networks 1 «ΤΟ ΟΠΑ ΕΡΕΥΝΑ» 11.03.2014

2. Outline 2 1994, Nobel Econ.2001Grand Bazaar, IST

3. Motivation & Challenges(1) “The number of mobile-connected devices will exceed the world’s population by 2014”, Cisco, 2014 Map of Fon Wi-Fi APs in (part of) London, April 2013 – via http://corp.fon.com/mapshttp://corp.fon.com/maps 3

4. Motivation & Challenges(2) via wikipedia: Europe mobile phone penetration map 4

5. Motivation & Challenges(3) Too many devices coexist in the same area and compete for radio spectrum – (-) very limited resource The problem: (-) Too much interference The challenge: (How) Can we control it? 5 National Telecommunications and Information Administration, Spectrum Map, USA, 2012

6. On the Interference Mitigation in Wireless Networks Through… Power control (PC): How to choose the transmission power to achieve a Quality of Service (QoS) target Some challenges for a successful power control algorithm [1] 6 http://wcdma3g.blogspot.gr/

7. Power Control Using Game Theory We focus on scenarios where nodes have different QoS targets and (at least some of) them are autonomous (e.g., APs) We need distributed power control schemes Competition for resources among players =(non-cooperative) game theory Key Issues/Our Roadmap: Has the game a Nash Equilibrium (NE)? How can we find it? Is it unique? If not, which to choose? Is it (Pareto) efficient? 7

8. Non-Cooperative Power Control in Small Cell Networks [2] low-power devices that operate in licensed spectrum More devices…more interference! Two-tier small cell network Our work: Study efficient coexistence with GT 8 http://www.smallcellforum.org

9. Power Control & Bargaining for Wireless Providers Revenue Improvement Both Blue and Gold providers transmit at Pmax and earn X and Y € Our work: Can we do it better? Blue makes a ‘take it or leave it’ offer to the Gold – “I give you E € to reduce your power t times” – X’-E>X Gold accepts iff Y’+E>Y Win-win scenario 9

10. Power Control Using Bargaining in Wireless Devices (1) [3] 10 Trunc(ated) Power Control [Zander, TVT ’92] (-) Unfair for this node – no opportunity to achieve its target More importantly: how to oblige an autonomous entity to power off? I achieved my QoS target I am 40% below my QoS target  I am 20% below my QoS target  I am 15% below my QoS target 

11. Power Control Using Bargaining in Wireless Devices (2) 11 We cannot dictate to an AP to power off/reduce its power! Our work: Unsatisfied links negotiate in pairs. Each one uses part of its budget to make an offer to the other I achieved my QoS target I am 40% below my QoS target  I am 20% below my QoS target  I am 15% below my QoS target  I offer you 100 credits if you reduce your power 20% OK! No thanks!

12. Channel Access in Device-to- Device (D2D) Communication [4] More devices…more interference Our work: Channel access in D2D scenarios  which device should transmit/receive data when Devices decide autonomously using game theory 12

13. Glimpses of the Future We have a lot to do! Your contributions are welcome! ;-) 13

14. References [1] V.G. Douros and G.C. Polyzos, “Review of Some Fundamental Approaches for Power Control in Wireless Networks,” Elsevier Computer Communications, 2011. [2] V.G. Douros, S. Toumpis and G.C. Polyzos, “Power Control Under Best Response Dynamics for Interference Mitigation in a Two-Tier Femtocell Network,” Proc. WIOPT-RAWNET, 2012. [3] V.G. Douros, G.C. Polyzos and S. Toumpis, “Negotiation- Based Distributed Power Control in Wireless Networks with Autonomous Nodes,” Proc. VTC2011-Spring, 2011. [4] V.G. Douros, S. Toumpis and G.C. Polyzos, “On the Nash Equilibria of Graphical Games for Channel Access in Multihop Wireless Networks,” Proc. WCNC-Wireless Evolution beyond 2020, 2014. 14

15. Ευχαριστώ! Vaggelis G. Douros Mobile Multimedia Laboratory Department of Informatics Athens University of Economics and Business douros@aueb.gr http://mm.aueb.gr/~douros 15