  The quickly increasing data traffic and the user demand for a full coverage
of mobile services anywhere and anytime are leading mobile networking into a
future of small cell networks. However, due to the high-density and randomness
of small cell networks, there are several technical challenges. In this paper,
we investigate two critical issues: \emph{best signal quality} and
\emph{mobility management}. Under the assumptions that base stations are
uniformly distributed in a ring shaped region and that shadowings are
lognormal, independent and identically distributed, we prove that when the
number of sites in the ring tends to infinity, then (i) the maximum signal
strength received at the center of the ring tends in distribution to a Gumbel
distribution when properly renormalized, and (ii) it is asymptotically
independent of the interference. Using these properties, we derive the
distribution of the best signal quality. Furthermore, an optimized random cell
scanning scheme is proposed, based on the evaluation of the optimal number of
sites to be scanned for maximizing the user data throughput.
