We propose a method of simulating satellite link availability that uses three dimensional map data. Our method calculates the satellite signal reception level at a reception point by taking into account diffracted and/or reflected waves as well as direct waves. This paper identifies simulation parameters that enable calculations that show good agreement with measured satellite signal reception levels. Our work further shows the following. 1) To calculate satellite signal levels accurately it is necessary to take into consideration diffracted and reflected waves as well as direct waves. 2) The optimum reflection coefficient of building walls and roads was 10 dB for this evaluation environment. 3) The radius of the observation area where the reflected wave was calculated was about 150 m. This choice of area was made considering CPU time required to calculate one reception point. In future work the optimum radius will be determined by evaluating the accuracy of simulation results. The results confirmed that our satellite link availability analysis can effectively predict link conditions.