  We propose and evaluate the performance of a Non-Orthogonal Multiple Access
(NOMA) dual-hop multiple relay (MR) network from an information freshness
perspective using the Age of Information (AoI) metric. More specifically, we
consider an age dependent (AD) policy, named as AD-NOMA- MR, in which users
only transmit, with a given probability, after they reach a certain age
threshold. The packets sent by the users are potentially received by the
relays, and then forwarded to a common sink in a NOMA fashion by randomly
selecting one of the available power levels, and multiple packets are received
if all selected levels are unique. We derive analytical expressions for the
average AoI of AD-NOMA-MR. Through numerical and simulation results, we show
that the proposed policy can improve the average AoI up to 76.6% when compared
to a previously proposed AD Orthogonal Multiple Access MR policy.
