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

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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

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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)

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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!

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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

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Market Model Customers

choose provider based on QoS & fee

Providers allocate bandwidth

and subsidy money in regions

Government subsidize, encourage

serving roaming users

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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

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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

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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

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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

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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

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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

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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

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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

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Finally….

Thank You, Questions ?