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ABSTRACT: Extensive spectrum markets have the potential to enable more efficient use of this limited resource. Such markets must account for particular properties of the underlying wireless medium. In this paper we focus on one such aspect: the role of interference created among different agents who may purchase the right to use the same spectrum at nearby locations. Such interference can result in “complementarities” among the spectrum goods being traded, which complicates the design of an efficient market. We begin with a simple linear model for these complementarities that was shown to be computationally difficult in earlier work. We give several approximation algorithms for this model. We then consider several alternative models in which the spectrum goods are defined in different ways and explore the impact of these choices on the complexity of the resulting market.
Modeling and Optimization in Mobile, Ad Hoc and Wireless Networks (WiOpt), 2011 International Symposium on; 06/2011
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ABSTRACT: The FCC in the U.S. has recently increased the amount of spectrum available for wireless broadband data services by permitting unlicensed access to television white-spaces. While this additional unlicensed spectrum allows for market expansion, it also influences competition among providers and can increase congestion (interference) among consumers of wireless services. We study the value (social welfare) obtained by adding unlicensed spectrum to an existing allocation of licensed spectrum among incumbent Service Providers (SPs). We assume a population of customers who choose a provider based on minimum delivered price. Here, delivered price is the price of the service plus a congestion cost, which depends on the number of subscribers in a band. For the model considered, we find that the social welfare depends on the amount of additional unlicensed spectrum, and can actually decrease over a significant range of unlicensed bandwidths.
New Frontiers in Dynamic Spectrum Access Networks (DySPAN), 2011 IEEE Symposium on; 06/2011
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ABSTRACT: It is widely recognized that the centralized approach to spectrum management currently used in most countries has led to highly inefficient allocations. It is also recognized that more efficient allocations could be achieved through spectrum markets; however, most discussions have so far focused on secondary markets, which are managed by licensees. Here we take a more expansive view, and discuss some challenges and implications of implementing extensive spectrum markets across locations, time, and diverse sets of applications. The discussion is motivated by first examining the fundamental question: Is spectrum scarce or abundant? Given that spectrum is indeed scarce, and that spectrum property rights are appropriately defined, we speculate on the emergence of a two-tier market; the upper tier consists of spectrum owners that trade spectrum assets analogous to land rights, and the lower tier consists of spot markets for limited-duration rentals of spectrum assets from owners at particular locations. The changes such spectrum markets could bring to the provision of wireless services and wireless network design are discussed along with methods for addressing related interference management issues.
IEEE Communications Magazine 12/2010; · 3.79 Impact Factor
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ABSTRACT: It is widely recognized that current policies for allocating wireless spectrum have led to inefficiencies and under-utilization. One proposed solution to this is to enable "spectrum markets", which allow for entities to sell and/or lease spectrum dynamically over time. In this paper we consider the design of such a market and how this is influenced by the underlying properties of the wireless medium. In particular, we focus on the role of interference created by different agents who may purchase the use of the same spectrum band at nearby locations. Such interference can result in "complementarities" among the spectrum goods being traded, which complicates the design of an efficient market mechanism. We give a simple model for such complementarities and for which the efficient allocation of spectrum assets to agents can be formulated as an integer program. We characterize the computational complexity of this problem and and the performance of two different linear relaxations. We also comment on the optimal prices for such markets.
Communication, Control, and Computing, 2009. Allerton 2009. 47th Annual Allerton Conference on; 11/2009
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ABSTRACT: In previous work we have studied the use of sequential second price auctions for sharing a wireless resource, such as bandwidth or power. The resource is assumed to be managed by a spectrum broker (auctioneer), who collects bids and allocates discrete units of the resource. It is well known that a second price auction for a single indivisible good has an efficient dominant strategy equilibrium; this is no longer the case when multiple units of a homogeneous good are sold in repeated iterations. Previous work attempted to bound this inefficiency loss for two users with non-increasing marginal valuations and full information. This work was based on studying a setting in which one agent's valuation for each resource unit is strictly larger than any of the other agent's valuations and assuming a certain property of the price paid by such a dominant user in any sub-game. Using this assumption it was shown that the worst-case efficiency loss was no more than e<sup>-1</sup>. However, here we show that this assumption is not satisfied for all non-increasing marginals with this dominance property. In spite of this, we show that it is always true for the worst-case marginals for any number of goods and so the worst-case efficiency loss for any non-increasing marginal valuations is still bounded by e<sup>-1</sup>.
Game Theory for Networks, 2009. GameNets '09. International Conference on; 06/2009
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ABSTRACT: It has been suggested that light regulation in the form of etiquette protocols, device design and bargaining amongst users will suffice to mitigate a tragedy of the commons in unlicensed spectrum. In this paper we propose a game theoretic model to examine this claim. In this game, each user decides whether or not to set up an access point, which operates on a particular (single) band. The effect of regulation is modeled in reduced form through transfers. A user who sets up an access point, provides payments to each neighbor who does not and suffers a disutility depending on the number of interfering access points. A user who does not set up an access point, receives payments from each neighbor that does. For a suitable model of payoffs, the game is a potential game and best response updates converge to a Nash equilibrium of the game. For any interference parameters, there is a suitable transfer resulting in a Nash equilibrium which is efficient. However, all Nash equilibria may not be efficient.
New Frontiers in Dynamic Spectrum Access Networks, 2008. DySPAN 2008. 3rd IEEE Symposium on; 11/2008
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ABSTRACT: It has been widely recognized that the current under-utilization of spectrum across many bands could be alleviated through the application of spectrum markets. So far, discussions of market mechanisms for spectrum allocations have focused primarily on secondary markets, which are managed by licensees. Here we explore the consequences of lifting current restrictions on allocations and ownership, and allowing more extensive markets for allocating spectrum across locations, times, and diverse sets of applications (e.g., broadcast, cellular, broadband data, emergency, etc). To motivate our discussion we first estimate the achievable rate per user that could be provided by sharing a large portion of the spectrum suitable for cellular and broadcast types of services. Our results suggest that in general the demand for spectrum may exceed supply implying that market mechanisms are needed to avoid a tragedy of the commons (i.e., associated with an alternative commons model). We then discuss a two- tier spectrum market structure for wireless services in which licenses for spectrum assets at particular locations are traded as commodities. Spectrum owners can choose to rent or lease their spectrum assets via spot markets at particular locations. Such an approach may lower barriers to entry into the wireless services market thereby facilitating competition and the introduction of new services.
New Frontiers in Dynamic Spectrum Access Networks, 2008. DySPAN 2008. 3rd IEEE Symposium on; 11/2008
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ABSTRACT: We study a sequential auction for sharing a wireless resource (bandwidth or power) among competing transmitters. The resource is assumed to be managed by a spectrum broker (auctioneer), who collects bids and allocates discrete units of the resource via a sequential second-price auction. It is well known that a second price auction for a single indivisible good has an efficient dominant strategy equilibrium; this is no longer the case when multiple units of a homogeneous good are sold in repeated iterations. For two users with full information, we show that such an auction has a unique equilibrium allocation. The worst-case efficiency of this allocation is characterized under the following cases: (i) both bidders have a concave valuation for the spectrum resource, and (ii) one bidder has a concave valuation and the other bidder has a convex valuation (e.g., for the other useriquests power). Although the worst-case efficiency loss can be significant, numerical results are presented, which show that for randomly placed transmitter-receiver pairs with rate utility functions, the sequential second-price auction typically achieves the efficient allocation. For more than two users it is shown that this mechanism always has a pure strategy equilibrium, but in general there may be multiple equilibria. We give a constructive procedure for finding one equilibrium; numerical results show that when all users have concave valuations the efficiency loss decreases with an increase in the number of users.
IEEE Journal on Selected Areas in Communications 10/2008; · 3.41 Impact Factor
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ABSTRACT: Market-based mechanisms such as auctions have been widely considered for various network resource allocation problems. We consider such a mechanism motivated by dynamic spectrum sharing applications. In this model multiple homogeneous units of a given resource are to be allocated to two agents. We study a sequential second price auction for allocating these resource units. It is well known that such auctions can have inefficient equilibria. For the case of two bidders, we show that the value of the allocation obtained in the unique subgame perfect equilibrium is at least 1 - e<sup>-1</sup> of the value of the efficient allocation. Furthermore, we show that this bound is asymptotically tight as the number of goods increases.
Decision and Control, 2007 46th IEEE Conference on; 01/2008
