  Multi-access Edge Computing (MEC) enables computation and energy-constrained
devices to offload and execute their tasks on powerful servers. Due to the
scarce nature of the spectral and computation resources, it is important to
jointly consider i) contention-based communications for task offloading and ii)
parallel computing and occupation of failure-prone MEC processing resources
(virtual machines). The feasibility of task offloading and successful task
execution with virtually no failures during the operation time needs to be
investigated collectively from a combined point of view. To this end, this
letter proposes a novel spatiotemporal framework that utilizes stochastic
geometry and continuous time Markov chains to jointly characterize the
communication and computation performance of dependable MEC-enabled wireless
systems. Based on the designed framework, we evaluate the influence of various
system parameters on different dependability metrics such as (i) computation
resources availability, (ii) task execution retainability, and (iii) task
execution capacity. Our findings showcase that there exists an optimal number
of virtual machines for parallel computing at the MEC server to maximize the
task execution capacity.
