Field investigation of the radio transmission performance and distance in a environmental wireless sensor network

One of the problems affecting sensor networks in natural environments is the attenuation of radio waves due to high humidity. This attenuation is greatest in the case of a 2.4-GHz radio wave. A system is being developed that uses a transmission control method to estimate communication environment fluctuations caused by changes in the natural environment. This paper discusses the transmission performance in wireless sensor networks in terms of the relationships between wireless transmission performance, distance, and environmental conditions observed in field experiments. Measurements were made with sensor nodes equipped with a weather-sensing device at an experimental field of the university, called the Field Museum (FM) Tamakyuryo in Tokyo. Over the course of the two-month experiment, measurements of the parameters throughput, signal strength, humidity, and atmospheric pressure were taken in the field. The results confirmed that the distance between sensor nodes and the season of measurement affect the throughput and stability of data transmission. Therefore, it is suggested that node position, distance between nodes, and environmental conditions are important factors in improving transmission performance and battery efficiency for environmental wireless sensor networks.