The most widely publicized architecture for Wireless Sensor and Actuator Networks (WSANs) consists of microprocessor based motes, running the Tiny OS (mostly in the USA) or Contiki (mostly in Europe) operating systems, communicating via low power radios. Each WSAN has one (or a few) sink nodes, connecting the WSAN, possibly via other networks, such as the Internet, with its users. For minimizing power usage, communications between nodes and the sink(s) are multi-hop, implying that routing protocols are implemented in the motes for determining the best route to be followed. The IEEE 802.15.4 standard is often used for the physical and Medium Access Control (MAC) layers, at throughputs up to 250 Kb/s, but specific Radio Duty Cycling (RDC) protocols are added to the MAC layer for saving power. RDC protocols switch off the radios whenever possible, since the radio transceiver is typically the most power-consuming component. A set of IETF protocols allows integration of such WSANs in the IPv6 Internet, bringing the widely advertised Internet of Things (IoT) closer to practical feasibility by allowing to acquire data and gives commands through a web browser connected anywhere to the Internet.
The high frequency (2.4GHz) and the link budget of some 90 dB typical for the commonly used radios exclude however these WSANs for applications requiring radio waves to cross thick stone walls. New radios working in the SRD860 license free band [5], based upon spread spectrum techniques allow trading throughput for link budgets. These budgets can be as high as 150 dB, which allow crossing several walls. Commercial products using such radios are already available for utility metering and empty parking spot detection, but they use another networking paradigm than the traditional WSANs: they are based upon single-hop star networks built around base stations, somewhat like the cellular telephony networks. Their communications protocols are specifically tailored for the radios and interoperability with the now standardized WSANs was not a design goal.
This project will explore the feasibility and the possible benefits of an integration of these new radios in the framework of traditional WSANs. This integration requires the exploration of many issues, the most important being:

* Can the large amount of system software developed for traditional WSANs, such as the Contiki operating system or the COAP web server be adapted for working efficiently above these new long-range radios?
* Can spread spectrum radio links save energy by adopting multi-hop transmissions?
* How can routing protocols be extended to handle the possibility of trading transmission capacity for transmission range?
* Can these routing protocols be extended to handle two varieties of links with different physical properties and different regulatory constraints?
* Are hybrid WSANs (with two different radios) more performant or cost effective than homogenous ones?

Runtime: 2015 - 2015