  Driven by great demands on low-latency services of the edge devices (EDs),
mobile edge computing (MEC) has been proposed to enable the computing
capacities at the edge of the radio access network. However, conventional MEC
servers suffer disadvantages such as limited computing capacity, preventing the
computation-intensive tasks to be processed in time. To relief this issue, we
propose the heterogeneous MEC (HetMEC) where the data that cannot be timely
processed at the edge are allowed be offloaded to the upper-layer MEC servers,
and finally to the cloud center (CC) with more powerful computing capacity. We
design the latency minimization algorithm by jointly coordinating the task
assignment, computing and transmission resources among the EDs, multi-layer MEC
servers, and the CC. Simulation results indicate that our proposed algorithm
can achieve a lower latency and higher processing rate than the conventional
MEC scheme.
