Reliable cooperative scheme for public safety services in LTE-A networks

In order to enable effective public safety services in challenged environments, 3rd Generation Partnership Program is considering the use of device-to-device (D2D) communications. D2D communications can be ideal in various emergency situations where the conventional network services get suspended. We propose a D2D-based user equipment (UE) relaying process to support the out-of-range isolated UEs. The main idea is to allow UEs that have active connections with eNB to exchange data with the isolated UEs over direct D2D links. This paper proposes a mechanism that enables an ordinary UE to serve as a relay for the isolated UEs, considering the D2D link capacity and the relay's radial velocity. We define the complete procedure of establishing a reliable relay link between UEs in public safety environments and analyse its performance.