This book highlights the innovative applications of electromagnetics, optics, thermodynamics theories in creating methods for physical-layer collision prevention- "physical anti-collision" in radio frequency identification (RFID) systems. Using engineering mathematical methods as the core of detection and control algorithm design, it proposes semi-physical verification and detection techniques to the dynamic performance testing in RFID systems. The book also introduces the methods to build semi-physical hardware platforms using photoelectric sensing technology. The book provides valuable ideas to the applications of Internet of Things (IOT) systems in smart logistics, car networking, food traceability, anti-counterfeiting and other livelihood fields. It is worth reading for all researchers in IOT and optoelectronic engineering related industries.