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In this paper we present a transmission scheduling protocol for data-gathering Wireless Sensor Networks (WSN). We focus on the delivery performance in term of overall Packet Receive Ratio (PRR) at the sink node. In order to reduce the energy consumption and increase the overall delivery performance, elaborated scheduling algorithm is applied to the transmission and relaying of data packets, based on a beacon-broadcasting global synchronization. We tested the protocol using CiNet nodes, which is built on IEEE 802.15.4 compliant radio modules CC2420 and Jennic JN5148, and obtained significant delivery improvement in multihop scenarios. This protocol is suitable for energy-hungry data gathering wireless sensor networks in which the sensor nodes use a short time window for radio activities in order to save energy.

Wireless sensor networks can be used to perform structural monitoring. Strain gauges, which can be glued on or integrated to the observed material, are the most common nondestructive sensing elements for measuring surface strain. Wireless strain gauge measurement system makes strain measurements more flexible while opening new targets of application in addition to those that traditional wired strain measuring systems can offer. We have implemented a long term strain measurement in a PVC-covered hall using wireless sensor network. In this paper we evaluate the functionality and suitability of the developed wireless system for this kind of monitoring. The paper discusses the experiences gained in the development and utilization of a wireless strain gauge measurement system. The calibration of measurement system as well as energy consumption issues are also brought under observation along with the reliability of communication aspects in the described measurement case.