1. CISTER Research Unit, ISEP/IPP, Rua Dr. Antonio Bernardino de Almeida 431, 4200-072 Porto, Portugal
2. Instituto de Telecomunicações, University of Beira Interior, 6201-001 Covilhã, Portugal
3. University ITMO, Saint-Petersburg 197101, Russia
4. National University of Computer and Emerging Sciences, A. K. Brohi Road H-11/4, Islamabad 44000, Pakistan
5. Telecommunications Technological Centre of Catalonia, Avenida Carl Friedrich Gauss 7, 08860-Castelldefels, Spain
6. Department of EEIS, University of Science and Technology of China, Hefei, Anhui 230027, China