Abstract: This paper describes models and algorithms for realizing the reference model proposed in ITU-R M.1225 for each test-operating environment including indoor office, outdoor-to-indoor/pedestrian and vehicular. Besides the brief description of the scheme as a whole, we discuss two algorithms in detail that are adapted to be realized in real time:shaping of slow fading with correlation and generation of frequency-selected multipath fading. The numerical results and simulation statistics given in the end show that the simulator gives good simulations of the first-order and second-order statistic characteristics.