Age of Information in Energy-Harvesting-Enabled Random Access Networks

We study the age of information (AoI) in an energy harvesting-enabled random access network consisting of multiple source-destination dipoles. Every source node transmits a sequence of information packets to its destination over a shared spectrum using only the harvested energy. We consider that each information packet is encoded with finite-length codewords, thereby describing the nature of shortcode transmissions in random access networks. We derive closed-form expressions for the network average AoI in two special cases, i.e., the small and large energy buffer scenarios, respectively. Both results show that the average AoI under the considered network is equivalent to that in a random access network where energy is consistently available for each packet transmission but with a recalibrated update rate and a rectification term. Our analysis reveals that an optimal blocklength exists that minimizes the network average AoI, by balancing between the success decoding rate and interference across the network.