In this paper, the end-to-end error performance of conventional dual-hop system where a source communicates with the destination over an energy harvesting (EH) relay in the lack of a direct link between them, is investigated. In the first phase, relay decodes the signal received from the source, from which it harvests energy according to time switching (TS)-based relaying and power splitting (PS)-based relaying protocols, and uses this energy to transmit the decoded source signal to the destination. All nodes are assumed to be equipped by one antenna and the channels are exposed to Nakagami-m fading. Bit error probability (BEP) of the considered system is analytically derived for both EH protocols cited above. For TS protocol, a list of modulation mixture is provided for different values of the time allocation parameter alpha. Ideal EH case is considered for comparison purposes. Moreover, optimization of the system parameters to maximize the system error performance is performed. Computer simulation results are provided to support the theoretically derived results.