The document discusses different media access control (MAC) methods for wireless networks and their motivations. It describes that carrier sense multiple access with collision detection (CSMA/CD) used in fixed networks does not work well in wireless due to signal strength decreasing with distance and half-duplex radios. This can cause the "hidden terminal" and "exposed terminal" problems. It then introduces MACA, which uses request-to-send and clear-to-send packets to avoid collisions for hidden terminals. The document also discusses frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access (CDMA), space division multiple access (SDMA), and their characteristics.