On forecasting the ONU sleep period in XG-PON systems using exponential smoothing techniques. - Panagiotis G. Sarigiannidis; Athanasios Gkaliouris; Vasiliki L. Kakali; Malamati D. Louta; Georgios I. Papadimitriou; Petros Nicopolitidis; Mohammad S. Obaidat (GLOBECOM, 2014)