Infrared-based Short-Distance FSO Sensor Network System

Energy consumption is one of the major problems in the development of Wireless Sensor Network (WSN). Under certain application conditions, Free Space Optical (FSO) communication can effectively reduce system energy consumption. Combining the need of the short-distance communication in the cooperative control of the mobile robot, this paper focuses on the study for the infrared FSO communication method and devices. Eight infrared-transmitting and receiving modules with the angular spacing 45° were deployed to realize the omnidirectional communication. The systematic measurement shows that the designed communication system can effectively carry out data transmission within a distance of 14 meters when the bit error ratio (BER) is 0%. Through the link budget analysis, the theoretical transmission distance of the design system is about 24 meters, only accounting for 60% of the communication module data manual, and the BER rises rapidly as the distance increases. The analysis of the oscilloscope observation results indicates that due to the attenuation caused by each medium (mainly moisture, dust, etc.) in the propagation path, the BER rapidly increases when the distance increases. Therefore, based on the test results, this system is applicable for constructing a short-distance wireless sensor network to meet the needs of cooperative control of mobile robots, without involving the complicated pointing process.