In order to design successful Internet of Things (IoT) networks, prototyping and simulation are complementary techniques. This requires that the prototypes have enough hardware resources to run the entire IoT stack. Moreover, the simulators must be fine-tunable to accurately behave like the simulated network components at all the levels of the stack. Both must have facilities for measuring and reporting performance indices without significantly perturbing normal operation. This paper describes dual motes used as hardware building blocks to build prototype networks. They fulfill the enounced requirements and allow the experimental determination of the parameters necessary for extending the study of a prototype network by means of simulations.

We propose an adaptation of the well-known Time Slotted Channel Hopping (TSCH) Medium Access Control (MAC) protocol, which was initially specified for IEEE 802.15.4 based networks, for operation over the LoRa PHY layer. Thanks to its deterministic nature, multiple concurrent communications can be handled, while reducing channel collision and ensuring reliability in a power-efficient manner. The proposed solution was implemented in the Contiki-NG operating system and tested on real motes.

The Medium Access Control (MAC) protocol proposed by the evolving IEEE 802.15.4 standard for Low-power and Lossy Networks (LLNs) includes a multichannel mode known as Time-Slotted Channel Hopping (TSCH). TSCH, published in 2015, is part of the most recent version of the IEEE 802.15.4 standard. In this paper, we present a performance comparison between TSCH (with Orchestra scheduling algorithm) and EM-MAC, a contention-based multichannel MAC protocol for LLNs, in terms of average packet delivery ratio, power consumption and latency after network start-up phase. Results obtained from experiments on a testbed with Z1 nodes sending traffic to the sink in an environment with negligible external interference, follow the same trend as the ones obtained through a simulation study. TSCH/Orchestra outperforms EM-MAC or performs equally well for all considered loads. A point of attention though for TSCH, is the significant time required by newly joining nodes to associate to the TSCH network and to join the tree created by the IPv6 Routing Protocol for LLNs (RPL).

Several recent sensor platforms combine long-range and more classical short-range radio technologies. In this poster we propose some modifications to the RPL routing protocol such that it automatically selects the most suitable radio link when more than one is available. The solution has been implemented in the ContikiOS and tested on the Zolertia Re-mote platform.