Age of information for multi-user access cognitive radio system with an energy collection node

In order to solve the problem of limited channel resources of internet of things (IoT) and improve the information timeliness of IoT system, a multi-access Cognitive Radio (CR) IoT system model is constructed. The model includes one Primary User (PU) and two Secondary User (SU) nodes. PU has spectrum access rights and two SUs can share the PU spectrum. We study the latency and age of information (AoI) for secondary users in this system, where two secondary user nodes transmit different types of data to a common destination. The difference is that the first secondary user node is connected to the power grid and the data packet arrives in a burst manner. The second secondary user node has an energy harvesting sensor and generates new status updates with a certain probability. Considering the interference of the primary user, we derive the delay of the first and secondary user nodes and the AoI of the second user as functions of different parameters in the system. The simulation results show the influence of different system parameters on the delay and AoI of two secondary user nodes under PU interference.