This application note is one of three papers dealing with the WiMAX standard, addressing theoretical aspects of WiMAX. It provides a detailed overview of basic WiMAX concepts (including Fast Fourier Transform (FFT), Orthogonal Frequency-Division Multiplexing (OFDM), and frame structures), and explains the physical standard parts of IEEE 802.16, standards 802.16-2004, corr1. and 802.16e.