  Geo-location database-assisted TV white space network reduces the need of
energy-intensive processes (such as spectrum sensing), hence can achieve green
cognitive communication effectively. The success of such a network relies on a
proper business model that provides incentives for all parties involved. In
this paper, we propose MINE GOLD (a Model of INformation markEt for
GeO-Location Database), which enables databases to sell the spectrum
information to unlicensed white space devices (WSDs) for profit. Specifically,
we focus on an oligopoly information market with multiple databases, and study
the interactions among databases and WSDs using a two-stage hierarchical model.
In Stage I, databases compete to sell information to WSDs by optimizing their
information prices. In Stage II, each WSD decides whether and from which
database to purchase the information, to maximize his benefit of using the TV
white space. We first characterize how the WSDs' purchasing behaviors
dynamically evolve, and what is the equilibrium point under fixed information
prices from the databases. We then analyze how the system parameters and the
databases' pricing decisions affect the market equilibrium, and what is the
equilibrium of the database price competition. Our numerical results show that,
perhaps counter-intuitively, the databases' aggregate revenue is not monotonic
with the number of databases. Moreover, numerical results show that a large
degree of positive network externality would improve the databases' revenues
and the system performance.
