A Radio Channel Model for D2D Communications Blocked by Single Trees in Forest Environments. - Imanol Picallo; Hicham Klaina; Peio López-Iturri; Erik Aguirre; Mikel Celaya-Echarri; Leyre Azpilicueta; Alejandro Eguizábal; Francisco Falcone; Ana Vázquez Alejos (Sensors, 2019)