BROADCAST BASE STATION DEVICE, PORTABLE TERMINAL, HIERARCHICAL MODULATION METHOD SETTING METHOD, BROADCAST SYSTEM, AND HIERARCHICAL MODULATION METHOD SETTING PROGRAM

摘要

A broadcast base station device (1) transmits a broadcast wave modulated by the hierarchical modulation method to a portable terminal (2). A hierarchical modulation setting section (17) compares the reception quality of the broadcast wave at the portable terminal (2) with a predetermined reference quality. According to the comparison result, the hierarchical modulation setting section (17) sets the hierarchical modulation method. For example, the constellation in each quadrant is narrowed or broadened. With this, the broadcast base station device (1) can transmits a most suitable broadcast wave corresponding to the actual reception quality to portable terminals (2).