Published online by Cambridge University Press: 18 August 2022
Device-to-device (D2D) radio channels have fundamentally different properties compared to those of conventional cellular (device-to-infrastructure, D2I) channels. The main reason for this is that most often both the receive antenna and the transmit antenna are located at low heights, and hence there is more interaction with objects in the close neighborhood of the devices. Also, UE mobility, human presence, and finite multipath persistence are the principal factors that degrade link availability. Such models are the focus of this chapter.