Research on Debugging Interaction of IoT Devices Based on Visible Light Communication

Wireless sensors normally deployed in inaccessible areas. Once the wireless communication of sensor node fails, the lost node cannot be repaired by debugging interaction which depends on this communication. Visible light communication (VLC) is a supplement of the traditional radio-wave wireless communication by and needs a dedicated device or module. Thus, VLC is hard to be applied in low-cost sensor nodes. We implement a hybrid duplexing debugging interaction system (HDDIS) based on VLC in general smartphone and sensor node. The smartphone is taken as a VLC gateway to send debugging codes to the sensor node. In order to improve the VLC transmission rate of debugging codes, we propose a novel debugging code compression method for data source and channel coding. With regard to the data source, we analyze the binary instructions and reuse opcodes and leverage a bit-mask technique to compress operands. The average compression rate of binary instructions reaches 84.11%. For channel coding, we optimize the dual-header pulse interval modulation (DH-PIM) and propose the overlap DH-PIM (ODH-PIM) by introducing a LED half-on state. The LED half-on state can improve the representation ability of each symbol. The experiment results illustrate that our modulation reduces transmission time by 10.71% compared with DH-PIM.