The existing blind noise estimation called cyclic prefix based noise estimation without knowledge of a priori signal is simulated along with input of DVB-T and the multipath channel ITU-T pedestrian model A. The simulation is done by means to know NMSE and noise uncertainty over time observation with varied SNR. The NMSE shows a very good result and close to the result of the previous research. The corresponding noise uncertainty is simulated in order to observe the performance of detection of spectrum sensing. It has the result that such limitation of detection called SNR wall will not occur. Based on the research, the estimator is expected to be applied along with spectrum sensing in cognitive radio network.