In this paper, we analyze the performance of a wideband sum-of-cisoids (SOC) channel simulator w.r.t. the bit error probability (BEP) of differential phase-shift keying (DPSK) orthogonal frequency division multiplexing (OFDM) systems. Analytical BEP expressions are derived for coherent and non- coherent DPSK OFDM simulation systems in the presence of a wideband SOC channel simulator. We also study the degradations of the BEP introduced by an imperfect channel simulator. Using the deviation of the BEP as an appropriate measure, we evaluate the performance of three parameter computation methods, known as the method of exact Doppler spread (MEDS), the randomized MEDS (R-MEDS), and the Monte Carlo method (MCM). For coherent DPSK OFDM systems, it turns out that these three methods are equivalent. For noncoherent DPSK OFDM systems, it is theoretically shown that both the MEDS and the R-MEDS outperform the MCM. The correctness of all theoretical results are validated by simulations. density functions (PDFs) of the absolute value of the time- variant transfer function and the temporal-frequency correla- tion function (CF) of both channel models. Next, we derive the BEP expressions for the OFDM systems using coherent and noncoherent DPSK schemes. For the coherent DPSK OFDM system, we demonstrate that the BEP of the simulation system approaches to the reference BEP if the number of cisoids in the SOC channel simulator tends to infinity. Based on the analytical BEP results, we discuss the deviation between the reference BEP and the BEP of the simulation system. Then, we compare the performance of three parameter computation methods: the MEDS, the R-MEDS, and the MCM. We assume isotropic scattering conditions here. However, it should be mentioned that the obtained BEP expressions are general and also applicable to non-isotropic scattering conditions. The rest of this paper is organized as follows. In Section II, we first give a brief review of the frequency-selective ref- erence channel model and the corresponding SOC channel simulator. Then, we study the statistical properties of both channel models. Section III provides an analysis of the BEP performance of coherent DPSK OFDM systems. In Section IV, we concentrate on the noncoherent DPSK OFDM system performance analysis. Finally, the conclusions are given in Section VI.