Age of Information in Random Access Channels

In applications of remote sensing, estimation, and control, timely communication is critical but not always ensured by high-rate communication. This work proposes decentralized age-efficient transmission policies for random access channels with $M$ transmitters. We propose the notion age-gain a packet to quantify how much will reduce instantaneous age information at receiver side upon successful delivery. then utilize this policy in which transmitters act manner based on age-gain their available packets. particular, each transmitter sends its latest only if corresponding beyond certain threshold could be computed adaptively using collision feedback or found as fixed value analytically advance. Both methods improve significantly compared state art. limit large , we prove that when arrival rate small (below notation="LaTeX">$\frac {1}{eM}$ ), slotted ALOHA-type algorithms are order optimal. As increases while under ALOHA, it decreases proposed age-based policies. For rates notation="LaTeX">$\theta $ =\frac {1}{o(M)}$ provide multiplicative gain least two minimum ALOHA (minimum over all rates). conclude beneficial increase sampling (and hence rate) transmit packets selectively age-gain. surprising contrary common practice where optimized attain AoI. further extend our results other technologies such Carrier-sense multiple (CSMA).