Editorial: Special Issue on Serving and Managing Users in a Heterogeneous B3G Wireless World - Requirements, New Research Challenges, Emerging Solutions. - Panagiotis Demestichas; Angeliki Alexiou; Joseph Marcos Katz; Djamal-Eddine Meddour; Knud Erik Skouby (Wirel. Pers. Commun., 2009)