The problem we consider is motivated by allocating bandwidth slots
to
communication requests on a satellite channel under real time
constraints.
Accepted requests must be scheduled on non-intersecting
rectangles in the time/bandwidth Cartesian space with the goal of
maximizing the benefit obtained from accepted requests.
This problem
turns out to be equal to the maximization version of the well known
Dynamic
Storage Allocation problem when storage size is limited and requests
must be accommodated within a prescribed time interval.
We present constant approximation algorithms for the problem introduced
in this paper using as a basic step the solution of a fractional Linear Programming formulation.
We also show the extension to the case in which multiple channels
are available for accepting communication requests.
This problem has been independently studied by Bar-Noy et al \cite{BBFNS00}.
The techniques we use are different from those of \cite{BBFNS00}
and allows to obtain better approximation ratio.