WSN monitoring system for greenhouse environmental parameters and CC2530 transmission characteristics

Abstract: Aiming at the problems of traditional greenhouse environment monitoring systems such as complicated wiring, high cost, inflexible monitoring, and high energy consumption of previous wireless sensor networks (WSNs), this paper designed a WSN-based greenhouse environmental parameter monitoring system, constructed its hardware with a CC2530 wireless sensor network chip and peripheral interface, compiled its underlying software by using the protocol stack of Z-Stack, and developed the PC software of greenhouse environment monitoring system based on a VB software platform. The transmission characteristics of a CC2530 chip was analyzed, and the experimental results showed that the effective transmission distance of the nodes was 60 m when they were placed 1.5 m above the ground. The connection between RSSI and the distance of nodes could be seen that the transmission power of the nodes gradually increased with the change of distance. The magnitude of RSSI attenuated faster when the distance of nodes was between 0 to 20 m. The fluctuation of RSSI because of the signal was blocked by the jatropha in the greenhouse, and the average height of jatropha was 2 m. The packet loss rate started to increase when the RSSI was less than -80 dBm, and the basic signal transmission capability of nodes was lost when the RSSI was less than -90 dBm. Besides, a single node with two 5th batteries could sustain the acquisition of greenhouse environmental parameter data for 45 d and accurately detect the temperature, humidity, and soil volumetric water content for greenhouse environment. During the experiment of energy consumption, the sensor nodes of soil moisture acquired data every half-hour, and the sensor nodes of temperature and humidity collected data every hour. The sensor nodes of soil moisture significantly consumed more energy than the sensor nodes of temperature and humidity under the same conditions of power transmission after 20 d. There was a slight increase for the voltage of nodes in the process of dormancy. Once the voltage of nodes falls below 3 V, although it has few impacts to the capacity of signal transmission, it may lead to abnormal work for the sensors. Above all, this system was proved to be practical and reliable.