The Internet of Things (IoT) ecosystems can be susceptible to exploitation by adversaries, who may target device software, hardware, communication channels, or protocols. My research recognizes the IoT security challenges arising from resource and capability limitations and embraces an alternative physical layer security approach. This approach takes into account the limited resources of IoT devices. By employing a spectrum-sharing communication framework, my research concentrates on enhancing the quality of service of wireless signals through cooperative communications among IoT devices. Importantly, these proposed schemes complement, rather than replace, traditional security measures.