On Forwarding Protocols in Linear Topology Wake-up Wireless Sensor Networks

Wake-up radio (WuR) is a kind of ultra-low power transceiver that consumes energy at 1000 times lower in magnitude when compared to the main radio in traditional wireless sensors. When incorporated, traditional wireless sensor networks are possible to improve energy efficiency and packet delay simultaneously by mitigating idle listening and overhearing issues. In recent years, many works have designed and evaluated the performance of MAC protocols in WuR-enabled yet single-hop (i.e. star-shaped) wireless sensor networks. This paper moves to a multi-hop network and focuses on linear topology WuR-enabled WSNs. It makes practical sense as large-scale WSN topologies could be decomposed into multiple linear topologies. Based on WuR inherent characteristics and also signal interferences among adjacent sensors, we introduce some interesting design ideas and describe our proposed MAC protocol in detail. Analytical results on expected radio-on time of intermediate sensors when waken up are derived. Also numerical results based on normalized per-hop energy and delay ratios show the effectiveness of our protocol. It may serve as an interesting basis for potential researches into more realistically large-scale WuR-enabled WSNs.