  Content delivery success in wireless caching helper networks depends mainly
on cache-based channel selection diversity and network interference. For given
channel fading and network geometry, both channel selection diversity and
network interference dynamically vary according to what and how the caching
helpers cache at their finite storage space. We study probabilistic content
placement (or caching placement) to desirably control cache-based channel
selection diversity and network interference in a stochastic wireless caching
helper network, with sophisticated considerations of wireless fading channels,
interactions among multiple users such as interference and loads at caching
helpers, and arbitrary memory size. Using stochastic geometry, we derive
optimal caching probabilities in closed form to maximize the average success
probability of content delivery and propose an efficient algorithm to find the
solution in a noise-limited network. In an interference-limited network, based
on a lower bound of the average success probability of content delivery, we
find near-optimal caching probabilities in closed form to control the channel
selection diversity and the network interference. We numerically verify that
the proposed content placement is superior to other comparable content
placement strategies.
