MAC Protocols with Wake-up Radio for Wireless Sensor Networks: A Review

Abstract

The use of a low-power wake-up radio in wireless sensor networks is considered in this paper, where relevant medium access control solutions are studied. A variety of asynchronous wake-up MAC protocols have been proposed in the literature, which take advantage of integrating a second radio to the main one for waking it up. However, a complete and a comprehensive survey particularly on these protocols is missing in the literature. This paper aims at filling this gap, proposing a relevant taxonomy, and pro- viding deep analysis and discussions. From both per- spectives of energy efficiency and latency reduction, as well as their operation principles, state-of-the-art wake-up MAC protocols are grouped into three main categories: i) duty cycled wake-up MAC protocols, ii) non-cycled wake-up protocols, and iii) path reserva- tion wake-up protocols. The first category includes two subcategories, i) static wake-up protocols vs. ii) traffic adaptive wake-up protocols. Non-cycled wake- up MAC protocols are again divided into two classes i) always-on wake-up protocol, and ii) radio-triggered wake-up protocols. The latter is in turn split into two subclasses: i) passive wake-up MAC protocols, vs. ii) ultra low power active wake-up MAC protocols. Two schemes could be identified for the last category, broadcast based wake-up vs. addressing based wake- up. All these classes are discussed and analized in this paper, and canonical protocols are investigated following the proposed taxonomy.