1. German Aerospace Center (DLR), Oberpfaffenhofen, Wesling, Germany
2. Brain and Artificial Intelligence Lab, School of Automation, Northwestern Polytechnical University, Xi’an, China
3. Department of Telecommunications, UPB, Bucharest, Romania
4. School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai, China
5. UPB, Bucharest, Romania