A multi-winner cognitive spectrum auction game in Java Incoporate Quick Response Code in Java A multi-winner cognitive spectrum auction game

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A multi-winner cognitive spectrum auction game using none tocompose none for web,windows application MSI Spectrum auction none none is one important approach for dynamic spectrum allocation, in which secondary users lease some unused bands from primary users. However, spectrum auctions are different from existing auctions studied by economists, because spectrum resources are interference-limited rather than quantity-limited, and it is possible to award one band to multiple secondary users with negligible mutual interference. To accommodate this special feature in wireless communications, in this chapter, we present a novel multi-winner spectrum auction game that does not not exist in the auction literature.

Since secondary users may be sel sh in nature and tend to be dishonest in pursuit of higher pro ts, we develop effective mechanisms to suppress their dishonest/collusive behaviors when secondary users distort their valuations about spectrum resources and interference relationships. Moreover, in order to make the game scalable when the size of the problem grows, the semi-de nite programming (SDP) relaxation is applied to reduce the complexity signi cantly. Finally, simulation results are presented in order to evaluate the auction mechanisms, and to demonstrate the reduction in complexity.

. Introduction With the develop none none ment of cognitive radio technologies, dynamic spectrum access has become a promising approach. This allows unlicensed users (secondary users) dynamic and opportunistic access to the licensed bands owned by legacy spectrum holders (primary users) in either a non-cooperative fashion or a cooperative fashion. In non-cooperative dynamic spectrum sharing, secondary users existence is transparent to primary users, and secondary users frequently have to sense the radio environment to detect the presence of primary users.

Whenever they nd a spectrum opportunity when the primary user is absent, secondary users are allowed to occupy the spectrum; but they must immediately vacate the band when the primary user appears. However, imperfect spectrum sensing may lead to missed spectrum opportunities as well as collision with primary users. To circumvent the dif culties, an alternative is the cooperative approach whereby spectrum opportunities are announced by primary users rather than discovered by secondary users.

Since primary users have an incentive to trade their temporarily unused bands for monetary gains and secondary users want to lease some bands for data transmission, they may negotiate the price for a short-term. A multi-winner cognitive spectrum auction game lease. With the none for none emerging applications of mobile ad hoc networks envisioned in civilian usage, it is reasonable to assume that secondary users are sel sh and aim at maximizing their own interests because they do not serve a common goal or belong to a single authority. Since they are operated by humans or service providers, they are also capable of acting intelligently.

The spectrum resource is quite different from other commodities in that it is interference-limited rather than quantity-limited, because it is reusable by wireless users who are geographically far apart. In some application scenarios where secondary users need to communicate only within a short range, such as a wireless personal area network (WPAN) centered around a person s workspace, the transmission power is quite low, and hence even users separated by moderate distances can simultaneously access the same band. In this case, allowing multiple winners to lease the band is an option that is consented to by everyone: primary users get higher revenue, secondary users get more chances to access the spectrum, and the spectrum-usage ef ciency is boosted also from the system designer s perspective.

To the best of our knowledge, no such auction exists in the literature, and we coin the name multi-winner auction to highlight the special features of the new auction game, in which auction outcomes (e.g., the number of winners) highly depend on the geographical locations of the wireless users.

Moreover, since secondary users are sel sh by nature, they may misrepresent their private information in order to gain a higher payoff. Therefore, proper mechanisms have to be developed to provide incentives to reveal true private information. Although the Vickrey Clarke Groves (VCG) mechanism is a possible choice for enforcing that users bid their true valuations [78], it is also well known to suffer from several drawbacks such as low revenue [8] [101].

Since auction rules signi cantly affect bidding strategies, it is of essential importance to develop new auction mechanisms to overcome the disadvantages. In addition, mechanisms to be developed should take into consideration the collusive behavior of sel sh users, which is a prevalent threat to ef cient spectrum utilization but has generally been overlooked [207]. Driven by their pursuit of higher payoffs, a clique of secondary users may cheat together, and sometimes they may even have a more facilitated way to exchange information for collusion if they belong to the same service provider.

Furthermore, by awarding the same band to multiple buyers simultaneously under interference constraints, the multi-winner auction makes possible new kinds of collusion [464], besides the bidding-ring collusion discussed in the previous chapter. Emerging kinds of collusion will be discussed in detail later in this chapter, and effective countermeasures against them have to be developed. To make the spectrum auction scheme feasible, it must be easy to implement, and must be scalable when more and more users are incorporated into the auction game.

However, as we analyze later in this chapter, the optimal resource allocation that maximizes the system utility in the auction is an NP-complete problem whose exact solution needs a processing time that increases exponentially with the size of the problem, and hence the computational complexity becomes too formidable for this scheme to be.
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