  A device-to-device (D2D) wireless network is considered, where user devices
also have the ability to cache content. In such networks, users are mobile and
communication links can be spontaneously activated and dropped depending on the
users' relative position. Receivers request files from transmitters, these
files having a certain popularity and file-size distribution. In this work a
new performance metric is introduced, namely the Service Success Probability,
which captures the specificities of D2D networks. For the Poisson Point Process
case for node distribution and the SNR coverage model, explicit expressions are
derived. Simulations support the analytical results and explain the influence
of mobility and file-size distribution on the system performance, while
providing intuition on how to appropriately cache content on mobile storage
space. Of particular interest is the investigation on how different file-size
distributions (Exponential, Uniform, or Heavy-Tailed) influence the
performance.
