The notion of a fusion frame arises naturally in the context of frames in a Hilbert space. When viewing frames as sequences of rank-1 projections satisfying the two famous frame inequalities, the definition of a fusion frame stems from admitting projections onto higher-dimensional subspaces. On the other hand, necessary and sufficient conditions for piecing local frames together to a global frame (and vice versa) are given by the definition of a fusion frame, making fusion frames also a useful tool for distributed processing tasks in applications.

After a short recapitulation of frame theory, some basic principles of fusion frame theory will be motivated and discussed. I will not only present some analogies between frames and fusion frames, but also emphasize on some of the subtleties that appear in the (higher-dimensional) fusion frame case. I will present some questions concerning fusion frame systems (which model the interplay between the three frame layers subspace-, local- and global frames in distributed processing procedures) and some of my recently submitted results answering these. Finally, I will discuss some open problems for fusion frames.