Design of WSN node with adaptive transmitting power for rice field

Abstract: The environmental factors during the rice growing process have wide changes and most of the energy consumption of the sensor node is used for transmitting data. Meantime, wireless sensor networks on the basis of reliable communication consuming the lowest energy, has been a hot research topic. In order to establish a long time, stable and highly reliable wireless sensor network, a node for working on the rice fields was designed. The basis experiments study the relationship between plant height, leaf area, and the growth days and the impact on the radio channel. The basis results showed that the relationship of the plant height of the rice and the growth days caused attenuation to exist according to a logarithmic model, and the regression coefficient R2 was in the range of 0.9604 and 0.9485. Plant height and leaf area increase reduced the radio signal strength and communication success rate. The experimental results also showed that increasing the transmitting power could improve communication quality because of the rice growth factor for adverse wireless channel impact. First, sensor nodes use sleeping waking up as a working mechanism to reduce power consumption. Second, to extend the working time and improve communication quality, the node uses under rice growth cycle, the communication distance, the received signal strength, the average packet loss rate and other factors, automatically adjusts the transmitting power of the energy adaptive mechanisms. The experiments demonstrated that the larger transmitting power had the effective communication distance farther and rice density and height had important impact on the wireless communication. Finally, the verification experiments results proved that if the transmitting power was less than 5 dBm, the transmitting power changes had little effect on the working current of the node. Meantime, the verification experiments showed the node operating current was less than 40 mA. Moreover, with increasing transmit power the communication success rate improved dramatically. The node reducing the transmitting power in the allowable range still resulted in a high communication success rate. With this power adaptive strategy, the wireless node working in rice tiller and heading time, the impact of transmitting power changing on the communication quality was finished. The results showed that the average packet loss rate was 5% or less, and that the received signal strength stayed within acceptable range. In short, the node designing achieved the desired purpose.