A packet identifier table for use in conjunction with an input processor in a re-multiplexing module is divided into an active table and a pending table. A calculating step calculates errors for the prediction results, which are obtained for respective prediction methods in the prediction step, and a prediction error comparing step compares the prediction errors with respect to each of the prediction methods, which are calculated by the calculating step, to detect a moving speed of the mobile radio terminal. The current-diffusion has a hetero-structure having a third semiconductor layer constituted of InxGa1-xN and a fourth semiconductor layer constituted of n-Aly1Gay2Iny3N, the third semiconductor layer having a thickness of 10 nm or more and 25 nm or less. When performing exhaustive initial cell searches, primary synchronization codes that lead to unsuitable cells are excluded from subsequent initial cell searches performed on the same frequency.