  The age of information (AoI) performance metric for point-to-point wireless
communication systems is analytically studied under Rician-faded channels and
when the receiver is equipped with multiple antennas. The general scenario of a
non-linear AoI function is considered, which includes the conventional linear
AoI as a special case. The stop-and-wait transmission policy is adopted, where
the source node samples and then transmits new data only upon the successful
reception of previous data. This approach can serve as a performance benchmark
for any queuing system used in practice. New analytical and closed-form
expressions are derived with respect to the average AoI and average peak AoI
for the considered system configuration. We particularly focus on the energy
efficiency of the said mode of operation, whereas some useful engineering
insights are provided.
