How should the server sleep? – Age-energy tradeoff in sleep-wake server systems

The surging demand for fresh information from various Internet of Things (IoT) applications requires oceans data sampled the physical environment to be transmitted and processed timely, which would lead huge energy consumption. We investigate sleep-wake strategies servers in communication systems reduce consumption while guaranteeing timely delivery users. Specifically, we a multi-source single-server queueing system propose novel strategy called Conditional Sleep (CS) scheme. Our analysis reveals that CS scheme outperforms widely-used Hysteresis Time (HT) Bernoulli (BS) schemes terms Age Information (AoI), retaining same rate Peak (PAoI). find increasing sleep period length leads reduction an increase PAoI, but it does not always AoI. Moreover, show using PAoI as freshness metric designing make server infinitely long due being determined by first-order statistics. further numerically having bufferless can achieve better PAoI-energy tradeoff than infinite buffer when large sampling rate.