Sleep scheduling in energy harvesting wireless body area networks

WBANs offer a variety of medical applications and have received considerable attention in recent years. Due to the limited energy of sensors, prolonging network lifetime is of paramount importance for WBANs. Although duty-cycling techniques can conserve energy consumption and energy harvesting techniques can provide extra energy supply, the former leads to huge data delivery delay and the latter cannot supply energy infinitely and stably. Therefore, how to maximize network lifetime at low latency is still an open and challenging problem. In this article, we introduce a three-level sleep scheduling strategy for EH-WABNs. The first level is sensor node scheduling, which minimizes the number of sensors in an active sensor group. The second level is active sensor group discovery, which finds the maximum number of active sensor groups to enable alternate work in different frames to the greatest extent. The third level is active sensor group scheduling, which assigns an active sensor group in each frame. Importantly, this article provides a novel route to reduce energy consumption in EH-WBNAs, i.e. a combination of sensor sleep scheduling and energy harvesting, and we believe that this design can also be useful for other network scenarios.