  In this letter, we investigate the impact of channel memory on the average
age of information (AoI) for networks with various packet arrival models under
first-come-first-served (FCFS) and preemptive last-generated-first-served
(pLGFS) policies over Gilbert-Elliott (GE) erasure channel. For networks with
Bernoulli arrival model, we first derive the average AoI under the pLGFS
queuing policy, and then characterize the AoI gap between the FCFS and pLGFS
policies. For networks with Bernoulli arrival and generate-at-will arrival
models, the AoI performances under the FCFS and pLGFS policies are derived
explicitly. For networks with periodic arrival model, we derive the closed-form
expression for the average AoI under pLGFS over a general GE channel and
propose a numerical algorithm for calculating that under FCFS efficiently. It
is revealed that for pLGFS policy, the average AoI increases monotonically with
channel memory $\eta$ at $\frac{\eta}{1-\eta}$ over the symmetric GE channel.
For FCFS, the average AoI increases even faster due to the queuing delay, with
an additional term related to the packet arrival rate.
