WSN Link Budget Analysis for Precision Agriculture

The reliability and efficiency of wireless sensor networks (WSNs) are dependent on the radio link power budget between network nodes. WSNs used in precision agriculture present an interesting problem given the link power budget is dependent on crop growth and terrain in addition to more common factors such as node spacing and antenna height. A generally accepted value for signal margin in a typical link budget is a received signal strength indication (RSSI) > 15dB above receiver sensitivity. This paper discusses the results of an experimental investigation of RSSI over irregular terrain within a range of node distances and antenna heights. Experimental data are compared to predictions from an irregular terrain electromagnetic propagation model (ITS) with good agreement. Preliminary data on propagation losses due to crop canopy is presented and a demonstration of link power budget analysis using the open-source ITS model is given.