A wireless sensor network for precision agriculture and its performance

The use of wireless sensor networks is essential for implementation of information and control technologies in precision agriculture. We present our design of network stack for such an application where sensor nodes periodically collect data from fixed locations in a field. Our design of the physical layer consists of multiple power modes in both the receive and transmit operations for the purpose of achieving energy savings. In addition, we design our MAC layer to use these multiple power modes to improve the energy efficiency of wake-up synchronization phase. Our MAC protocol also organizes all the sender nodes to be synchronized with the receiver simultaneously and transmit their data in a time scheduled manner. Next, we design our energy aware routing strategy that balances the energy consumption over the nodes in the entire field and minimizes the number of wake-up synchronization overheads by scheduling the nodes for transmission in accordance with the structure of the routing tree. We develop analytical models and simulation studies to compare the energy consumption of our MAC protocol with that of the popular S-MAC protocol for a typical network topology used in our application under our routing strategy. Our MAC protocol is shown to have better energy efficiency as well as latency in a periodic data collection application. We also show the improvements resulting from the use of our routing strategy, in simulations, compared with the case when the next hop is chosen randomly from the set of neighbors that are closer to the sink node. Copyright (C) 2011 John Wiley & Sons, Ltd.