IoT concept took a part in everyday lives. Environments became smart, suggestive, recognizing, and adopting to its user needs. However, energy efficiency, interoperability, security, and other issues are restricting the number of use-cases and ways the technology can be used. To cope with these issues, cross-layer approach in standard architectures is necessary. This way, information propagating from one layer to the another can significantly influence overall performances—it is necessary to understand and implement all the significant details that may enable and improve specific applications. Moreover, tremendous evolution in data acquisition and transfer is needed to consider efficient hardware and innovative software architectures that still need to be developed to make it a reality. This mostly introduces distributed intelligence for a reliable and effective processing of the information about the physical world that should provide a complete knowledge to the top running applications. These are related to the efficient usage of radio technologies usual referred as in outdoor, indoor, urban, rural environments, its ranges, and battery/battery-less usage. In addition, communication protocols should handle IoT requirements for multiple device, low-power, real-time operations, or satisfying timely consumer needs. Some further challenges involve efficient device discovery schemes, sleep-mode management, application requirements, security issues, or other power constraints.