Information Freshness of a Relay Priority Transmission System

Considering the impact of packet reliability on the freshness of information at the wireless sensor system, this paper proposes a status update system, which consists of two sources, a common relay, and a destination. The two sources are available to deliver information to the destination. We assume that the information transmitted by one source is more reliable than the other, and the destination is more inclined to receive the information generated from the reliable sources even though it is a bit delay compared to the information generated from the unreliable sources. In this paper, we utilize the stochastic hybrid system (SHS) technique to derive the average age of information (AoI) of the reliable system with the packet management policy, in which reliable packet can preempt unreliable packet. Simulation results show that the average AoI of the reliable source is affected by the generation rate of reliable packets, the service rate of the system, and the generation rate of unreliable packets under the preemption policy.