Design of a Gateway Based on Directional Antenna WSN in Paddy Field

This paper designs a WSN gateway for environmental monitoring of paddy field, which includes the hardware structure and the software program. We use the MSP430F149 as the core of the gateway node and the nRF905 as the peripherals equipment for node communication. We choose TDR-3, a soil moisture sensor, and DHT22, a temperature-humidity sensor, to collect and process the environmental information of the paddy field in real time. The MC55 is used as the GPRS module to achieve communication between the gateway and the Internet. We write programs of hardware drivers, communication protocol, abnormal SMS alarm and time synchronization protocol based on the hardware platform. The communication distance, power consumption and data storage rate of the gateway are tested in paddy field. Tests results show that, in open area, the maximum distance of effective communication can reach 331.18m, the longest working hour without charging is 32days, the maximum storage rate is 849.7kbps, the packet loss rate is 0.686% under local network and 0.712% between local network and the internet. The gateway has the characteristics of stable operation, long-time-low-power consumption, long distance transmission and automatic alarm. It can meet the requirement of information acquisition of environmental monitoring in paddy field.