  Caching popular content at the wireless edge is recently proposed as a means
to reduce congestion at the backbone of cellular networks. The two main actors
involved are Mobile Network Operators (MNOs) and Content Providers (CPs). In
this work, we consider the following arrangement: an MNO pre-installs memory on
its wireless equipment (e.g. Base Stations) and invites a unique CP to use
them, with monetary cost. The CP will lease memory space and place its content;
the MNO will associate network users to stations. For a given association
policy, the MNO may help (or not) the CP to offload traffic, depending on
whether the association takes into account content placement. We formulate an
optimization problem from the CP perspective, which aims at maximizing traffic
offloading with minimum leasing costs. This is a joint optimization problem
that can include any association policy, and can also derive the optimal one.
We present a general exact solution using Benders decomposition. It iteratively
updates decisions of the two actors separately and converges to the global
optimum. We illustrate the optimal CP leasing/placement strategy and hit
probability gains under different association policies. Performance is
maximised when the MNO association follows CP actions.
