Secure energy efficiency of selective decode and forward with distributed power allocation

We investigate the secure energy efficiency of a cooperative network where two legitimate users (Alice and Bob) communicate with the help of a relay node, in the presence of a passive eavesdropper (Eve). Power is adequately allocated between Alice and the relay using a Dinkelbach-based iterative power allocation algorithm. We assume channel state information of the legitimate channel only and compare the secure energy efficiency of several cooperative schemes, namely, selective decode-and-forward (SDF), fixed decode-and-forward (DF), amplify-and-forward (AF) and cooperative jamming (CJ). Our results show that, in terms of secure energy efficiency, SDF outperforms the other cooperative schemes in many scenarios. However, when the transmit rate increases or when Eve is close to the legitimate nodes, CJ stands out as the most advantageous scheme.