  One of the key-points for the future developments of the multiconjugate
adaptive optics for the astronomy is the availability of the correction for a
large fraction of the sky. The sky coverage represents one of the limits of the
existing single reference adaptive optics system. Multiconjugate adaptive
optics allows to overcome the limitations due to the small corrected field of
view and the Layer Oriented approach, in particular by its Multiple Field of
View version, increases the number of possible references using also very faint
stars to guide the adaptive systems. In this paper we study the sky coverage
problem in the Layer Oriented case, using both numerical and analytical
approaches. Taking into account a star catalogue and a star luminosity
distribution function we run a lot of numerical simulation sequences using the
Layer Oriented Simulation Tool (LOST). Moreover we perform for several cases a
detailed optimization procedure and a relative full simulation in order to
achieve better performance for the considered system in those particular
conditions. In this way we can retrieve a distribution of numerically simulated
cases that allows computing the sky coverage with respect to a performance
parameter as the Strehl Ratio and to the scientific field size.
