1. Fostering Wireless Spectrum Sharing via Subsidization Allerton 2013 Murat Yuksel Computer Science and Engineering Department, University of Nevada, Reno Joint with T. Quint, I. Guvenc, W. Saad, and N. Kapucu

2. 2 Outline Pervasive Spectrum Sharing Overview Challenges and need for subsidy Proposed Spectrum Subsidization Market Market Model Formulation as a non-cooperative game Roles of customers, providers, government Key insights and observations Conclusion and future work

4. 4 Demand for Radio Spectrum Demand for wireless capacity to double every year (Cisco) Re-thinking the way in which spectrum is shared Allocating additional spectrum/re-assigning spectrum Opening up spectrum for unlicensed use (cognitive) New architectures (HetNets) and technologies (D2D)

5. 5 Challenges to Spectrum Sharing Operators paid a lot of money to acquire their spectrum Need incentive for opening up their spectrum Existing spectrum sharing approaches (auctions) are rather “closed” but must remain intact How to allow sharing along with such auctions? Success of new technologies such as D2D is contingent upon a “pervasive” spectrum sharing Need for subsidization!

6. 6 Subsidization What is subsidization? Government policies to encourage operators to open their spectrum to “roaming” users Governmental regulatory incentives for providers Many existing works on regulations in different disciplines Often ignore the idea of “performance-based” subsidy Do not focus on the role of subsidy in seamless spectrum sharing Role of government less explicit

7. 7 Market Model Customers choose provider based on QoS & fee Providers allocate bandwidth and subsidy money in regions Government subsidize, encourage serving roaming users

8. 8 Market Model Seamless to customers Customers subscribe to a home provider Then pick the best quality signal offered by the providers participating in the subsidy market Customers with no home providers are possible! Performance-based Providers have to return a portion of the subsidy money if insufficient “foreign” (roaming) customers are served Steerable policy Government can steer the market via a more aggressive penalty function – potentially per region

9. 9 Game Formulation Two-stage, extensive form non-cooperative game Players: Providers, Government Extensive form since: government moves first, followed by providers (move simultaneously) Customers not involved in the game as their actions are a byproduct of providers/government interactions Solution: Perfect Nash equilibrium Knowing customers actions, solve for providers Knowing customers/providers actions, solve for government subsidy

10. 10 Game Formulation Choice of customer i Choose provider with probability (contest theory): Provider’s problem Total revenue in a region: No. Calls in “home region” Fee charged by provider j Intensity of signal of provider j in region k Selection based on signal quality & subscription fee

11. 11 Game Formulation Provider’s problem Constraints # foreign calls: Penalty function on the number of “foreign calls” Investment and BW designated for region k Total subsidy Total investment Selection purely based on signal quality

12. 12 Game Formulation Government’s problem Maximize customers total utility Analytical solution for equilibrium complex but.. …several insights can be derived …key observations Utility from local calls Utility from foreign calls

13. 13 Key Observations Providers are unlikely to get hurt by subsidy Providers are free not to take subsidization option if it hurts their revenues (seen from optimization problem) Conservative government penalization can lead to easy providers participation The government can provide large subsidy with low risks and incentivize providers Providers will be motivated to invest in a non-overlapping manner and collectively cover a larger area

14. 14 Key Observations : As the # of customer calls to “foreign providers” increases, subsidization becomes more beneficial particularly to small providers Providers with only few home regions can take subsidization and promote “pervasive” sharing : small providers are able to compete with large providers Monopolies avoided as long as providers are attracted to subsidization

15. 15 Conclusions and Future Works Subsidization could play a key role in enabling pervasive spectrum sharing The success of technologies such as D2D depends not only on the “technical” aspects but also on policy and economic aspects Future works Extending the model and providing quantitative closed form solutions to subsidization at equilibrium Heterogeneous providers Specific technologies

16. 16 Finally…. Thank You, Questions ?