Physical-Layer Protocols for Lightweight Wildlife Tags with Internet-of-Things Transceivers

Most species of birds and bats must be tracked with tracking tags weighing less than 10g and many require tags weighing less than 1g. Tags based on commodity internet-of-things system-on-chips (SoC) can be be mass produced at low-cost, hence allowing many individuals to be tracked. We report on the design and performance of two communication protocols that enable long-range communication with such tags. One is a unidirectional protocol, in which tags transmit unique codes that can be reliably detected from 15km away and that can be used for time-of-arrival and angle-of-arrival localization (tracking). The other is a bidirectional protocol that allows tags to transmit short data packets to low-power low-cost basestations and to receive commands from them. Data packets in this protocol can be reliably received from tags that are 8km away and sometimes from up to 15km, and commands packets can be received by tags from up to 4km away. These protocols have been implemented in low-cost tags that can weigh less than 1g (depending on the choice of battery) and using only about 60uJ per transmission. Our results have been gathered by tagging wild bats. The same tags have been used for time-of-arrival localization of wild bats and birds by several different research groups in 3 countries.