What is D2D (Device-to-Device)?

Device-to-Device (D2D) communication in cellular networks is characterized as direct communication between two cell phones subscribers without traversing the Base Station. D2D communication is non-transparent to the cellular network. It can happen at cellular frequencies. D2D communications can greatly enhance the spectral efficiency of the network. D2D communications are used for spectral capability. It can enhance throughput, energy efficiency, delay, and fairness.