In wireless sensor networks (Wsns) energy efficiency and communication reliability are often conflicting requirements. additionally, some application areas such as industrial automation or infrastructure monitoring impose strict latency bounds.Low-power receivers ( mW 1 1 power consumption) together with adapted mac protocols have the potential to meet these diverse requirements. We present an overview of state-of-the-art low-power receivers and relate their characteristics to requirements for different application areas. We compare low-power receivers to duty-cycled transceivers and present applications depending on them. For this, we use power consumption, sensitivity, and data rate as key performance figures for low-power receivers. Based on the characteristics of the applications we derive guidelines for using low-power receivers instead of duty-cycled transceivers. project "AETERNITAS".Johannes Blanckenstein works on communication protocols in the general field of wireless sensor networks and especially on protocols and applications for low-power wake-up receivers. He writes his doctoral thesis at University Paderborn in the computer networks group of Holger Karl. At the same time he works at Airbus Group Innovations in the field of WSN applications for aeronautics.

In wireless sensor networks (WSNs) it is often required to have a common time basis for all sensor nodes. Due to clock drift it is necessary to re-synchronize the nodes repeatedly to keep the common time basis. But this re-synchronization can be power demanding. We present an energy-efficient approach which can bound the synchronization error to a certain limit. Either duty-cycled transceivers or wake-up receivers (WURs) can be used. Using WURs is the more energy-efficient and robust approach but needs special hardware.

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Abstract-Intelligent environments (IE) leverage embedded processing and wireless communication to assist users in a variety of ways. Applications rely on low power consumption for longer lifetimes, though different applications require different Qualityof-Service (QoS) requirements from the MAC layer. Until now, low power has come at the cost of other QoS parameters such as latency or packet loss. This paper presents WoR-MAC, a wireless MAC protocol which allows pre-existing protocols to be combined with remote multi-node wake-ups. The protocols are embedded into Wake-on-Radio (WoR) frames, allowing nodes to sleep during periods of low activity and be woken asynchronously with a single short RF signal. After waking, nodes begin communication using the embedded MAC protocol. Once the nodes have been woken, they maintain the QoS of the original MAC, with greatly reduced power consumption. The results indicate that WoR-MAC maintains packet loss characteristics of CSMA-CA and TDMA, as well as latency after accounting for the duty cycle and collaborative parameter estimation, while reducing power consumption by up to 49%, very close to the lower bound given by the duty-cycle.