  In this paper, we analyze the average age of information (AoI) and the
average peak AoI (PAoI) of a multiuser mobile edge computing (MEC) system where
a base station (BS) generates and transmits computation-intensive packets to
user equipments (UEs). In this MEC system, we focus on three computing schemes:
(i) The local computing scheme where all computational tasks are computed by
the local server at the UE, (ii) The edge computing scheme where all
computational tasks are computed by the edge server at the BS, and (iii) The
partial computing scheme where computational tasks are partially allocated at
the edge server and the rest are computed by the local server. Considering
exponentially distributed transmission time and computation time and adopting
the first come first serve (FCFS) queuing policy, we derive closed-form
expressions for the average AoI and average PAoI. To address the complexity of
the average AoI expression, we derive simple upper and lower bounds on the
average AoI, which allow us to explicitly examine the dependence of the optimal
offloading decision on the MEC system parameters. Aided by simulation results,
we verify our analysis and illustrate the impact of system parameters on the
AoI performance.
