  Cellular data traffic almost doubles every year, greatly straining network
capacity. The main driver for this development is wireless video. Traditional
methods for capacity increase (like using more spectrum and increasing base
station density) are very costly, and do not exploit the unique features of
video, in particular a high degree of {\em asynchronous content reuse}. In this
paper we give an overview of our work that proposed and detailed a new
transmission paradigm exploiting content reuse, and the fact that storage is
the fastest-increasing quantity in modern hardware. Our network structure uses
caching in helper stations (femto-caching) and/or devices, combined with highly
spectrally efficient short-range communications to deliver video files. For
femto-caching, we develop optimum storage schemes and dynamic streaming
policies that optimize video quality. For caching on devices, combined with
device-to-device communications, we show that communications within {\em
clusters} of mobile stations should be used; the cluster size can be adjusted
to optimize the tradeoff between frequency reuse and the probability that a
device finds a desired file cached by another device in the same cluster. We
show that in many situations the network throughput increases linearly with the
number of users, and that D2D communications also is superior in providing a
better tradeoff between throughput and outage than traditional base-station
centric systems. Simulation results with realistic numbers of users and channel
conditions show that network throughput (possibly with outage constraints) can
be increased by two orders of magnitude compared to conventional schemes.
