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In wireless networks, it is important to determine the outcome of packet transmissions for networking protocols. In this paper, we design a transmission outcome classifier for IEEE 802.15.4 wireless networks based on received signal strength indicator and link quality indicator values. Our classifier performs loss differentiation by analyzing statistical differences between weak signal and collision losses. We implement our proposed classifier using the CC2500 RF transceiver and evaluate it experimentally. The results show that our classifier can accurately detect packet transmissions as well as distinguish wireless losses due to weak signals and multiple access collisions, with a maximum error rate of 15%. We apply the classifier to probabilistic polling, which is a MAC protocol designed for energy harvesting wireless sensor networks, and show experimentally that it is able to achieve close to or even exceed the theoretical throughput due to packet capture effect.

Energy harvesting wireless sensor networks (EH-WSNs) are gaining importance in smart homes, environmental monitoring, health care and transportation systems, since they enable much longer operation time as energy can be replenished through energy harvesting. This is unlike sensor nodes that use non-rechargeable batteries which need to be replaced once energy is depleted. However, the sporadic availability of ambient energy makes the design of networking protocols and predicting network performance very challenging. In this paper, we perform an empirical energy characterization of a time-slotted solar energy harvesting node with different system and environmental parameters. We use six different statistical models (uniform distribution, geometric distribution, transformed geometric distribution, Poisson distribution, transformed Poisson distribution and a Markovian model) to fit the empirical datasets. Our results show that there is no single statistical model that can fit all the datasets, thus justifying the need to use empirical data to validate the theoretical analysis of time-slotted MAC protocols for EH-WSNs.

In an environmentally-powered wireless sensor network, where nodes are powered solely by harvesting energy from ambient sources, node operation highly depends on the energy availability and harvesting rate. For duty-cycling schemes to support existing wireless sensor network applications, they need to adapt the nodes' sleep-wake schedules according to energy harvesting and consumption rates. In this paper, we propose a harvesting-aware duty-cycling scheme, perform an empirical study of this scheme over a solar harvesting powered wireless sensor network in a source-relay-sink configuration, and provide some experimental results to illustrate its throughput performance under various light conditions.

A wireless multihop network is a communications network composed of nodes equipped with wireless interfaces and organized in an ad hoc manner. It has become an attractive and practical solution for providing flexible and extended wireless coverage over large areas. Measurement of physical layer quantities can provide useful information in the design of networking protocols and cross-layer optimization. In this paper, we present a cost-effective approach of performing physical-layer and link-layer measurements by exploiting the capabilities of inexpensive commercial-off-the-shelf (COTS) wireless routers and open-source software tools. Our experimental results show that the measurements made using inexpensive wireless routers are consistent with theoretical models and hence reliable. It is therefore possible to utilize the measurements to devise models or algorithms that will improve the performance of networking protocols.