  Providing femto-access points (FAPs) with computational capabilities will
allow (either total or partial) offloading of highly demanding applications
from smart-phones to the so called femto-cloud. Such offloading promises to be
beneficial in terms of battery saving at the mobile terminal (MT) and/or
latency reduction in the execution of applications, whenever the energy and/or
time required for the communication process are compensated by the energy
and/or time savings that result from the remote computation at the FAPs. For
this problem, we provide in this paper a framework for the joint optimization
of the radio and computational resource usage exploiting the tradeoff between
energy consumption and latency, and assuming that multiple antennas are
available at the MT and the serving FAP. As a result of the optimization, the
optimal communication strategy (e.g., transmission power, rate, precoder) is
obtained, as well as the optimal distribution of the computational load between
the handset and the serving FAP. The paper also establishes the conditions
under which total or no offloading are optimal, determines which is the minimum
affordable latency in the execution of the application, and analyzes as a
particular case the minimization of the total consumed energy without latency
constraints.
