It is common that users or hosts in a large network are partitioned and organized as a hierarchical tree where children of the same parent form a group. Secure broadcasting intends to provide a secure communication channel from a sending principal to a group of legal receiving principals. Only legal receiving principals can decrypt the message, and illegal receiving principals cannot acquire an...

With the rapid development of high-speed railway systems and wireless communication, application ultra-wideband millimeter wave band is an inevitable trend. However, channel has large propagation loss easy to be blocked. Moreover, there are many problems such as eavesdropping between base station (BS) train. As emerging technology, reconfigurable intelligent surface (RIS) can achieve effect pas...