Three-tier wireless sensor network for environmental monitoring
Naiqian Zhang, Han Wei · 2010
ABSTRACT Three-tier wireless sensor networks were designed and deployed in several experimental sites to remotely monitor sediment concentration and movement in real time. Sensor nodes, gateways, repeater stations, and central stations were strategically deployed to insure reliable signal transmissions. Radio signal strength was tested to analyze effects of distance, vegetation, and topographical barriers. Omniand directional antennae with different gains were tested to achieve robust, long-range connection in a wireless-hostile environment. Sampling times of sensor nodes within a local sensor network were synchronized at the gateway station. Error detection algorithms were developed to detect errors caused by interference and other impairments of the transmission channel. Both GSM and CDMA modems were used at different locations based on cellular coverage. Procedures for selection of solar power components were developed and tested. Data were analyzed to verify the design principles.