◼ 2.1Antennas, Propagation and Propagation Characteristics (天线、传输、 传输特性) 2.1.1 Classifications of Transmission Media 2.1.2 Introduction to Antennas 2.1.3 Propagation Modes ◼ Ground-wave propagation ◼ Sky-wave propagation ◼ Line-of-sight propagation 2.1.4 LOS Wireless Transmission Impairments 2.1.5 Fading ◼ 2.2 Spread Spectrum(扩频) 2.2.1 The Concept of Spread Spectrum 2.2.2 Frequency Hopping Spread Spectrum 2.2.3 Direct Sequence Spread Spectrum 2.2.4 Code Division Multiple Access