1. Department of Electrical & Computer Engineering, Democritus University of Thrace, 67100 Xanthi, Greece
2. Buissiness Area Networks, Technology & Strategy, Standardts & Technology, Radio & Antennas, Radio Antennas & Algorithms, Ericsson, 16480 Stockholm, Sweden
3. College of Engineering & Computing, Florida International University, Miami, FL 33174, USA