  In this paper, we study the joint computation offloading and resource
allocation problem in the two-tier wireless heterogeneous network (HetNet). Our
design aims to optimize the computation offloading to the cloud jointly with
the subchannel allocation to minimize the maximum (min-max) weighted energy
consumption subject to practical constraints on bandwidth, computing resource
and allowable latency for the multi-user multitask computation system. To
tackle this non-convex mixed integer non-linear problem (MINLP), we employ the
bisection search method to solve it where we propose a novel approach to
transform and verify the feasibility of the underlying problem in each
iteration. In addition, we propose a low-complexity algorithm, which can
decrease the number of binary optimization variables and enable more scalable
computation offloading optimization in the practical wireless HetNets.
Numerical studies confirm that the proposed design achieves the energy saving
gains about 55% in comparison with the local computation scheme under the
strict required latency of 0.1s.
