In this paper, the bit error performance of an energy harvesting (EH) cooperative amplify-and-forward (AF) relaying system, in which the relay harvests energy from radio frequency source signal and then uses this energy to transmit its signal to the destination in the presence of a direct link between the source and the destination, is investigated in Nakagami- m fading channel. A unified approach to the analysis of bit error probability (BEP) is presented for the cases where the relay harvests energy based on power splitting (PS), time switching (TS) and ideal operational modes. Simulation results validate the theoretical analysis performed for coherent M-PSK and M-QAM and different system parameters. Dual-hop EH and conventional non-EH cooperative AF relaying systems are considered for comparison purposes. The obtained results show that the system bit error rate performance is mostly dependent on the channel parameter m and the energy harvesting parameters. (C) 2019 Elsevier B.V. All rights reserved.