Abstract: The freshness of information is crucial to the accurate decision-making and reliable operation of the status update system. In order to characterize the information freshness of a non-orthogonal multiple access (NOMA) based status update system with mobile edge computing (MEC), the age of information (AoI) has been investigated while taking into account both the local and the edge computing schemes. First, queuing theory is utilized to mimic the transmission and computation of status update information. Then, the service rate of transmission queue, which hinges on the quality of NOMA transmission, is analyzed, and closed-form expressions for the system average AoI are derived. Monte Carlo simulations verify the validity of the obtained analytical results. It follows from the simulation results that compared to orthogonal multiple access (OMA), the system AoI performance can be enhanced more dramatically by applying NOMA-MEC with higher server computation rate. In addition, simulation results demonstrate the effects of the system parameters, such as server computation rate, status update information size, and transmission power, on the AoI performance.

Key words: non-orthogonal multiple access, mobile edge computing, age of information, status update system