This graduate-level text aims to familiarize the reader with the technologies related to the time division duplex (TDD) mode of code division multiple access (CDMA) technology for mobile communications, which is becoming part of the wideband CDMA standards. While much of the literature on the technology is available in individual papers, Esmailzadeh and Nakagawa (both of the department of electrical engineering, Keio U., Japan) argue that the growing usefulness of the technology necessitates a book- length treatment. They cover TDD transmission, power control in TDD- CDMA systems, pre-rake diversity combining, system capacity in TDD- CDMA systems, TDD-based CDMA standards for public systems, TDD spread spectrum-based private systems, and TDD and fourth-generation systems.