Orthogonal frequency division multiplexing (OFDM) has been attracting much attention due to the robustness against the frequency selective fading. Instead of well-known cyclic prefix (CP) insertion, a known training sequence (TS) insertion can also be used for OFDM block transmission. In this paper, we propose a new receiver design, which can obtain the frequency diversity gain through the use of frequency-domain equalization (FDE), for TS-OFDM. The conditional bit error rate (BER) analysis of the proposed FDE is presented. The average BER performance of the TS-OFDM signal transmission in a frequency-selective Rayleigh fading channel is evaluated by Monte-Carlo numerical computation method using the derived conditional BER and is confirmed by computer simulation. Numerical results show the proposed TS-OFDM receiver improves BER and throughput performances of TS-OFDM compared to the conventional TSOFDM receiver. It was also shown that the TS-OFDM with the proposed receiver provides better BER and throughput performances than the CP-OFDM due to the frequency diversity gain.