  With the advent of the modern mobile traffic, e.g., online gaming, augmented
reality delivery and etc., a novel bidirectional computation task model where
the input data of each task consists of two parts, one generated at the mobile
device in real-time and the other originated from the Internet proactively, is
emerging as an important use case of 5G. In this paper, for ease of analytical
analysis, we consider the homogeneous bidirectional computation task model in a
mobile edge network which consists of one mobile edge computing (MEC) server
and one mobile device, both enabled with computing and caching capabilities.
Each task can be served via three mechanisms, i.e., local computing with local
caching, local computing without local caching and computing at the MEC server.
To minimize the average bandwidth, we formulate the joint caching and computing
optimization problem under the latency, cache size and average power
constraints. We derive the closed-form expressions for the optimal policy and
the minimum bandwidth. The tradeoff among communications, computing and caching
is illustrated both analytically and numerically, which provides insightful
guideline for the network designers.
