WuRx

One of the very few commercially available is a low-power, low-frequency wake-up receiver chip with addressing capability AS3932 [14]. Gamm et al. [15] designed a low-power WURx circuitry around it. The main transceiver produces a 125 kHz wake-up signal OOK (On Off Keying) modulated on an 868 MHz carrier. They report communication range of 45 m when transmitting with main high-consuming transceiver with +11 dBm and over 15 m when using 0 dBm output power.

6. Conclusions and Future WorkWake-up Radio (WuR) systems provide significant energy savings for wireless sensors when compared to conventional duty-cycling approaches. In this paper, we investigated and characterized a promising novel WuR approach that is based on SubCarrier Modulation (SCM), which enables two radio operation modes. When the remote sensor node is in low-power wake-up mode, a Wake-up Call (WuC) can trigger it remotely. Afterwards, the node switches to data communication mode to start the data exchange, e.g., wirelessly reply a transducer measure back. In this paper, we analyzed the performance results of the SCM-WuR approach and compared them to state-of-the-art WuR systems as of 2013. We conveyed the detailed performance analysis of the SCM-WuR approach in terms of wake-up delay, current consumption and overall operational range. Through physical tests, measurements and simulations, we have shown that SCM-WuR systems feature an outstanding tradeoff between hardware complexity, current consumption and operational range. We also demonstrated how SCM-WuR systems enable multi-hop wake-up for even longer remote sensor measure collection. For this purpose, we implemented a wake-up relay node and characterized its operation through delay and current consumption analysis. Finally, we have presented two real sensor monitoring application cases with SCM-WuR system, one single-hop and one multi-hop scenario, and calculated the lifetime and packet delivery ratio of the latter through simulations. Indeed, SCM-WuR systems effectively enable a vast range of applications, while most state-of-the-art proposals are restricted to short and medium-range scenarios. To the best of authors’ knowledge, this study is the first one to perform such type of global analysis in the field of Wake-up Radio systems. As future work, we target the evaluation of SCM-WuR design for different frequency bands, a feature that allows its integration into different wireless technologies.