In this paper, the authors present new frequency domain architecture for the digital block of a hardware simulator of MIMO propagation channels. This simulator can be used for LTE and WLAN IEEE 802.11ac applications, in indoor and outdoor environments. It accepts signals in streaming mode. A hardware simulator must reproduce the behavior of the radio propagation channel, thus making it possible to test \"On table\" the mobile radio equipments. The advantages are: low cost, short test duration, possibility to ensure the same test conditions in order to compare the performance of various equipments.