Other Topics in Digital Mobile Radio Transmission

This chapter describes the diversity transmission system, multi‐input multi‐output (MIMO) systems, adaptive automatic equalizers, error control techniques, trellis modulation, adaptive interference cancellation, and voice coding. It discusses the MIMO systems as diversity systems and space‐division multiplexing (SDM) transmission placing emphasis on explanation of their principles. The chapter gives a short introductory description of automatic equalizers and applications to mobile radio channels. To cope with errors in digital transmission, it discusses two countermeasures, namely, error correction and retransmission. Trellis‐coded modulation is a combined coding and modulation technique: coding and modulation are integrated to achieve better error rate performance without compromising bandwidth. Interference cancellation must be adaptive since both the interfering signal and the desired signal are time varying in mobile radio communications. The most straightforward system for voice coding is the usual analog‐to‐digital conversion at periodic sampling instants.